This document describes a study that uses diagenetic modeling software to assess the relative timing of quartz cementation and brittle grain fracturing during burial compaction. The study examines samples from the Oligocene Frio Formation in the Gulf of Mexico Basin and the Cambrian Mount Simon Formation in the Illinois Basin. For the Mount Simon samples, the extent of grain fracturing correlates with reconstructed stress levels at the onset of cementation. However, for the Frio samples, the extent of fracturing does not correlate as well with reconstructed stress levels from basin modeling, suggesting overpressures developed at shallower depths than the models indicate. The degree of fracturing in sandstones provides observable evidence that can help understand complex pressure histories
Effect of Sericitization on the Engineering Properties of the Miango Granite ...iosrjce
The effects of sericitizaition on the engineering properties of the Miango Granite porphyry located
in Bassa Local Government Area (L.G.A), Plateau State, Nigeria was carried out. The tests carried out on the
twenty rock samples include; aggregate crushing and impact tests, water absorption, durability tests, specific
gravity and petrographic examination. An average aggregate crushing value of >20% for most of the rock
samples show that the rocks are relatively weak while other tests such as aggregate impact values of 18%-23%,
water absorption of <1%,><12% and specific gravity values are fairly
good. However, thin section studies revealed three distinctive features which greatly influence the physicomechanical
properties: (a) abundant fractures of varying sizes (b) sericitization of the orthoclase/plagioclase
feldspars (c) intergrowth of quartz with plagioclase or orthoclase feldspars. The strength loss of the granite
porphyry could be attributed to the presence of micro-fractures on the rock samples and the sericitization of the
dominant plagioclase and orthoclase feldspars. Geotechnical characterization of the rocks shows that they can
be utilized as roadstone or could be cut and polished and used as facing stones because of slow disintegration to
sulphate attack and the large feldspar phenocrysts in the rock samples
This document describes two types of S-C mylonites:
Type I S-C mylonites involve narrow zones of intense shear strain that cut across a pre-existing mylonitic foliation. They typically occur in deformed granitoids.
Type II S-C mylonites have more widespread occurrence in quartz-mica rocks subjected to intense non-coaxial laminar flow. The C-surfaces are defined by trails of mica "fish" formed by microscopic displacement discontinuities or zones of very high shear strain. The S-surfaces are defined by oblique foliations in adjacent quartz aggregates formed by dynamic recrystallization.
Geological and Geotechnical Parameters Controlling Wall Paints Detachment at...IJMER
1) The document examines the geological and geotechnical factors controlling the detachment of wall paints at selected tombs from the 26th Dynasty in Bahariya Oasis, Egypt.
2) Field and laboratory studies were conducted on the Badi Eshtar and Bannantiu tombs to determine the impact of iron oxide content in the bedrock and quantify the damage levels to the wall paints.
3) The results found that moisture condensation inside the tombs from temperature differences between inside and outside, along with the micro-pore size distribution controlled by iron oxide, resulted in damage levels ranging from moderate to very severe at the two sites.
The document summarizes a study that used electron backscatter diffraction (EBSD) to measure the development of subgrain misorientation angles with increasing strain in dry synthetic sodium chloride (NaCl) deformed at elevated temperatures. The study found that average subgrain boundary misorientations increased with strain following a power law relationship. The average misorientations were influenced by grain orientation and size, suggesting texture and grain size may also impact the misorientation-strain relationship. The results indicate average subgrain boundary misorientations could provide a method for estimating strain from dislocation creep, though other factors like stress may also influence misorientations.
Evidence of Geological Control on Reservoir Petrophysical Properties of “Beta...Premier Publishers
Geological controls on the reservoir petrophysical properties of “BETA Field” have been carried out using suites of wireline logs. Stratigraphic relationship among the reservoir sand bodies including their geometrical architectures, and their stacking patterns were also established. Exponential regression analysis of some of the petrophysical parameters were carried out to establish any relationship with depositional processes as well as depositional environments of the reservoir sand bodies in the field. The main factor controlling petrophysical properties and thickness for these reservoirs is the type of sandstone facies. The petrophysical evaluation of both reservoirs (K and Q) depicts porosity range from fair to very good across wells (i.e 11% to 25%). From the evaluated reservoirs porosity, there is no significant reduction of porosity with depth increase. The values obtained for the permeability of both reservoirs (K and Q) varied widely and inconsistent across the wells in the study field. The various depositional environments established in BETA field include fluvial, tidal channel, mouth bars, delta front, and the reservoir sands occurring in different depositional settings, resulting from different depositional processes, which had a wide range of petrophysical properties.
This project characterized an unconventional Upper Jurassic reservoir in northern Mexico through an integrated geoscience analysis. The analysis included well log evaluation, seismic analysis, and geological modeling to predict total organic carbon (TOC) and brittleness distributions in 3D and characterize natural fractures and in situ stresses. TOC and brittleness predictions from well data correlated highly with seismic attributes and rock properties. While the seismic survey was not wide-azimuth, fracture information could still be extracted and correlated with wellbore images. The results provide insights into the reservoir's potential for hydraulic fracturing and hydrocarbon production from the shale formation.
1) The document discusses evidence for a unique mantle source rich in nickel that may originate from Earth's core. This source has been identified through analysis of primary mantle-derived magmas away from plate boundaries.
2) This mantle source contains about 20% more nickel than normal upper mantle rock and has a primordial helium isotopic signature. The proposed location is the core-mantle boundary.
3) Nickel is proposed to have partitioned into the mantle from the core at the extreme pressures at the core-mantle boundary, leaving a remnant primordial basal magma ocean enriched in nickel and primitive helium isotopes at this location today.
Effect of Sericitization on the Engineering Properties of the Miango Granite ...iosrjce
The effects of sericitizaition on the engineering properties of the Miango Granite porphyry located
in Bassa Local Government Area (L.G.A), Plateau State, Nigeria was carried out. The tests carried out on the
twenty rock samples include; aggregate crushing and impact tests, water absorption, durability tests, specific
gravity and petrographic examination. An average aggregate crushing value of >20% for most of the rock
samples show that the rocks are relatively weak while other tests such as aggregate impact values of 18%-23%,
water absorption of <1%,><12% and specific gravity values are fairly
good. However, thin section studies revealed three distinctive features which greatly influence the physicomechanical
properties: (a) abundant fractures of varying sizes (b) sericitization of the orthoclase/plagioclase
feldspars (c) intergrowth of quartz with plagioclase or orthoclase feldspars. The strength loss of the granite
porphyry could be attributed to the presence of micro-fractures on the rock samples and the sericitization of the
dominant plagioclase and orthoclase feldspars. Geotechnical characterization of the rocks shows that they can
be utilized as roadstone or could be cut and polished and used as facing stones because of slow disintegration to
sulphate attack and the large feldspar phenocrysts in the rock samples
This document describes two types of S-C mylonites:
Type I S-C mylonites involve narrow zones of intense shear strain that cut across a pre-existing mylonitic foliation. They typically occur in deformed granitoids.
Type II S-C mylonites have more widespread occurrence in quartz-mica rocks subjected to intense non-coaxial laminar flow. The C-surfaces are defined by trails of mica "fish" formed by microscopic displacement discontinuities or zones of very high shear strain. The S-surfaces are defined by oblique foliations in adjacent quartz aggregates formed by dynamic recrystallization.
Geological and Geotechnical Parameters Controlling Wall Paints Detachment at...IJMER
1) The document examines the geological and geotechnical factors controlling the detachment of wall paints at selected tombs from the 26th Dynasty in Bahariya Oasis, Egypt.
2) Field and laboratory studies were conducted on the Badi Eshtar and Bannantiu tombs to determine the impact of iron oxide content in the bedrock and quantify the damage levels to the wall paints.
3) The results found that moisture condensation inside the tombs from temperature differences between inside and outside, along with the micro-pore size distribution controlled by iron oxide, resulted in damage levels ranging from moderate to very severe at the two sites.
The document summarizes a study that used electron backscatter diffraction (EBSD) to measure the development of subgrain misorientation angles with increasing strain in dry synthetic sodium chloride (NaCl) deformed at elevated temperatures. The study found that average subgrain boundary misorientations increased with strain following a power law relationship. The average misorientations were influenced by grain orientation and size, suggesting texture and grain size may also impact the misorientation-strain relationship. The results indicate average subgrain boundary misorientations could provide a method for estimating strain from dislocation creep, though other factors like stress may also influence misorientations.
Evidence of Geological Control on Reservoir Petrophysical Properties of “Beta...Premier Publishers
Geological controls on the reservoir petrophysical properties of “BETA Field” have been carried out using suites of wireline logs. Stratigraphic relationship among the reservoir sand bodies including their geometrical architectures, and their stacking patterns were also established. Exponential regression analysis of some of the petrophysical parameters were carried out to establish any relationship with depositional processes as well as depositional environments of the reservoir sand bodies in the field. The main factor controlling petrophysical properties and thickness for these reservoirs is the type of sandstone facies. The petrophysical evaluation of both reservoirs (K and Q) depicts porosity range from fair to very good across wells (i.e 11% to 25%). From the evaluated reservoirs porosity, there is no significant reduction of porosity with depth increase. The values obtained for the permeability of both reservoirs (K and Q) varied widely and inconsistent across the wells in the study field. The various depositional environments established in BETA field include fluvial, tidal channel, mouth bars, delta front, and the reservoir sands occurring in different depositional settings, resulting from different depositional processes, which had a wide range of petrophysical properties.
This project characterized an unconventional Upper Jurassic reservoir in northern Mexico through an integrated geoscience analysis. The analysis included well log evaluation, seismic analysis, and geological modeling to predict total organic carbon (TOC) and brittleness distributions in 3D and characterize natural fractures and in situ stresses. TOC and brittleness predictions from well data correlated highly with seismic attributes and rock properties. While the seismic survey was not wide-azimuth, fracture information could still be extracted and correlated with wellbore images. The results provide insights into the reservoir's potential for hydraulic fracturing and hydrocarbon production from the shale formation.
1) The document discusses evidence for a unique mantle source rich in nickel that may originate from Earth's core. This source has been identified through analysis of primary mantle-derived magmas away from plate boundaries.
2) This mantle source contains about 20% more nickel than normal upper mantle rock and has a primordial helium isotopic signature. The proposed location is the core-mantle boundary.
3) Nickel is proposed to have partitioned into the mantle from the core at the extreme pressures at the core-mantle boundary, leaving a remnant primordial basal magma ocean enriched in nickel and primitive helium isotopes at this location today.
This field report summarizes the stratigraphy and oil trapping mechanisms of the J Sandstone in Kimball County, Nebraska. The J Sandstone consists of three members deposited in different environments: the lower J2 was deposited in shallow marine conditions, the overlying J1 indicates a transgression and was also deposited in shallow marine conditions, and the upper valley-fill member represents fluvial deposition. Stratigraphic traps within lenticular sandstone bodies and shale barriers, as well as structural traps associated with anticlines, control oil accumulation. Maps produced for this study indicate both stratigraphic and structural traps exist in the area that could be suitable for additional exploration and drilling.
Engineering geology is the application of the science of geology to the technology of ground engineering. The subject requires a comprehensive knowledge of geology, as well as an understanding of engineering properties and behaviour of the geological materials. The practice involves site investigation and site characterization specific to the needs of the engineering project. The geotechnical engineer plays a key role in most civil engineering projects as most structures are built on or in the ground. Geotechnical engineers assess the properties and behaviour of soil and rock formations.
Geoengineering Characterization of the Rock Masses of Northern Face of Jabal ...IJERA Editor
This paper is aimed at the description and the geotechnical characterization of the Tertiary granitic rock masses of the northern face of Sabir Mountain, Taiz city, Yemen, for the first time. For accomplishing this task, direct and indirect approaches are adopted. The direct approach is represented by field and laboratory investigations. Field investigations include discontinuity (joints) measurements/evaluation, applied Rock Mass Rating (RMR) system and Geological Strength Index (GSI) system, in addition to field tests, while laboratory investigations encompass physico-mechanical tests carried out on granitic rock materials. Indirect approach for the estimation of shear strength parameters (c, φ), compressive strength (σcm), tensile strength (σtm) and deformation modulus (Erm) of these rock masses was made by applying the generalized Hoek–Brown failure criterion using geotechnical Roc-Lab software. The laboratory results indicate that the Tertiary granitic rock masses show wide range of variations in their physico-mechanical characteristics owing to degree of weathering /alteration and microfractures. The intact samples of Sabir granitic (Tg) rocks show “Moderate” to “High” density, “Low” to "Medium" porosity, “Good" to "Marginal” water absorption capacity and “Weak” to “Very Strong” strength. Stereographically, three main sets of discontinuities (joints) are identified at each station; however, the fourth joint set occurs, in addition to random joint sets. The discontinuities (joints) trend predominately in NE-SW and NW-SE directions in conformity with the regional structures or faults. According to Jv j/m³ values, the degree of jointing of these rock masses are varied from “Moderate” to “High” jointing. These rocks are categorized as “Fair” to “Excellent” quality, “Fair” to “Good/Very Good” quality and “Poor” to “Very Good” quality classes according to RQD, RMR89 and GSI respectively. Values of the shear strength parameters (c and φ) and the other rock mass parameters (σtm, σc , σcm and Erm) show variations depending on the rock mass quality and properties of intact rock. However, in general the values of the rock mass parameters are found to increase with increase in the quality of rock mass and intact rock properties.
Soil and rock for geoscientist and engineersAinun Fatihah
This document summarizes key information about soils and rocks for geoscientists and engineers. It defines soil as unconsolidated mineral and organic material that forms in place and supports plant life, while rock is a solid aggregate of minerals. It describes the three main types of rocks - igneous, sedimentary, and metamorphic - and their formation processes. Several important properties of soils and rocks are also outlined, including particle size, density, porosity, plasticity, compressibility, shear strength, deformation, discontinuities, and methods for evaluating rock mass quality.
This document summarizes a study of soil geochemistry in Eruku and its environs, located in southwestern Nigeria. Twenty-five soil samples were collected and analyzed for trace element concentrations. Statistical analysis identified eleven factor groups in the data, with factors 2 and 5 related to mineralization. Isograde maps show peaks for elements like Be, Nb, Sn, and Ta in the northeast part of the study area. The study concludes that the area has anomalous concentrations of cassiterite, tantalite, and columbite hosted by pegmatites, particularly in the northeast quadrant, establishing a similar mineralization to the nearby Egbe area.
The memo discusses challenges facing the Green Bay High School Science Department and possible directions for the science curriculum. It summarizes recent changes made due to time constraints, including dropping internally assessed standards. It also discusses the need to provide students more time to assimilate course material and for practical science experiences. Finally, it proposes exploring a new educational paradigm centered around student access to online information and resources to support a more eclectic, non-linear learning experience in science.
This document provides an overview of soil mechanics as a discipline of civil engineering. It discusses the development of soil mechanics as a field systematized by Karl Von Terzaghi. The key topics covered include soil classification, compaction, soil-water relationships, stress distribution and settlement, shear strength, and slope stability. The overall objective is to impart knowledge on the physical and engineering behavior of soils, stress transfer in soils, and stability analysis of slopes. Various laboratory and field tests are also introduced to determine important engineering properties of soils.
Engineering geology involves the application of geology to construction projects. It is concerned with the rock and soil conditions of construction sites. Engineering geology provides information vital for planning, designing, and building structures like dams, bridges, and buildings. It examines the geology, geomorphology, and material properties of construction sites to understand subsurface conditions, availability of construction materials, and geologic hazards that could impact structures. Subdisciplines of engineering geology include physical geology, geomorphology, mineralogy, petrology, and economic geology. It aids in site selection, foundation design, and town planning by considering the geologic factors that influence construction and development.
This document provides an outline for a presentation on a deep-seated gravitational slope deformation in the northern Monashee Complex in British Columbia, Canada. It discusses what a DsGSD is, different approaches to studying them, and the objectives and methodology of this particular study. The study site is located near Blais Creek and exhibits characteristics like lithological weaknesses that make it prone to DsGSD. Field methods will include mapping surface features, geotechnical investigations, and trenching. Laboratory and modeling work will also be conducted to better understand the failure mechanism and incorporate the findings into an existing DsGSD database.
Kan bergartsfysikk og kvantitativ seismisk tolkning bidra til økt funnrate på...geoforskning
Rock physics provides a link between seismic data and reservoir properties by analyzing how physical rock properties affect seismic measurements. However, there are often more unknown variables than observable seismic attributes, creating a "bottleneck". Integrating rock physics with geological knowledge can help constrain non-unique interpretations. Accounting for varying rock stiffness is important, as cemented rocks may have low fluid sensitivity, making hydrocarbons difficult to detect seismically. Scale effects must also be considered, as properties vary between micro- and seismic-scales.
This document outlines the topics covered in the Engineering Geology and Seismology course. The course will discuss engineering geology, the role of geology in civil engineering, building stones, their characteristics and uses, and stone finishes. Key topics include how geology aids in foundation engineering, construction materials, and disaster mitigation. The course will also cover various building stone types like granite, sandstone, slate and marble.
Geology and groundwater quality assessment of ido osi area, southwestern nigeriaAlexander Decker
The document summarizes a study that assessed the geology and groundwater quality of the Ido/Osi area in southwestern Nigeria. Detailed geological mapping identified the dominant lithologic units as migmatites, gneisses, charnockites and granites. Water quality testing of 20 hand-dug wells found bacterial contamination above WHO standards and varying levels of physical and chemical parameters, though most were within WHO limits. The water chemistry showed moderate influence from the local bedrock. Regular monitoring is recommended given risks from contamination.
1. The document describes a research study on the mineralogical and geochemical characterization of mudrocks from the Neogene succession in Bangladesh.
2. The study will analyze mudrock samples using XRD, XRF, and laser particle size analysis to determine their depositional environments, diagenetic changes, and potential as petroleum seals or source rocks.
3. The research aims to better understand the clay mineralogy, elemental composition, grain size, and diagenetic alterations of mudrocks in two anticlines in Bangladesh and infer their depositional environments.
The foremost by-product of this paper is the automation of geological undertakings, for instance, dealing
with exceptionally thin sections of rocks that were subjected to deformation alongside finite steps of time
which can be recorded in video for later analysis using image processing and numerical analysis
procedures. Markers are used in order to trace gradients of deformation over a sample and study other
mechanical properties. Image processing and video sequence analysis can be a very powerful investigation
tool and this paper shows preliminary results from its use on microtectonics. The proposed algorithm is a
combination of two well-known approaches: feature extraction and block matching.
An application of the 2 d d.c. resistivity method in building site investigat...Alexander Decker
This study applied 2D DC resistivity methods to investigate the subsurface geology at a building site in south-south Nigeria. Two resistivity profiles identified four distinct geologic layers - a shallow clay layer, a layer of weathered rock materials, a layer of fractured basement rock, and fresh bedrock. The profiles revealed a potential geologic structure, likely a fracture, that could cause building failure if constructed across. The study concluded piles should extend to competent bedrock for major buildings, while shallow foundations can be used for small buildings, given the bedrock lies below weathered material. The integration of surface geophysics with borehole data would improve accuracy of the subsurface model.
Soil fauna and nutrient management for improving agricultural production thro...CSM _BGBD biodiversity
1) Farmers in Oumé, Côte d'Ivoire are facing decreasing soil fertility due to deforestation for cocoa and coffee farms. A study evaluated the effects of 9-month legume fallows using Pueraria phaseoloides and Cajanus cajan on soil properties, soil fauna, and subsequent maize growth.
2) The study found that legume fallows increased earthworm densities and diversity compared to a natural fallow control. Phytoparasitic nematode densities were also lower under legumes.
3) Maize yields were higher on legume fallow plots compared to the control, though not significantly for grain yield. Total biomass and 100
Geochemistry of Neogene mudrocks from Sitakund anticline, Bengal basin: Impli...Md. Yousuf Gazi
Geochemistry of Neogene mudrocks from Sitakund anticline, Bengal basin: Implications for provenance, weathering, tectonic setting and depositional environment.
This document contains 17 references related to rock mechanics and rock engineering. The references span from 1931 to 1994 and include journal articles, conference proceedings, books, theses, and reports. The references cover topics such as rock mass classification systems, shear strength of rock joints, rockfall analysis, tunnel support, and case histories of rock engineering projects.
Tissint Martian Meteorite: A Fresh Look at the Interior, Surface, and Atmosph...Carlos Bella
This document summarizes a study of the Tissint Martian meteorite that fell in Morocco in 2011. Key findings include:
- Tissint is a depleted picritic shergottite similar to meteorite EETA79001A, containing olivine macrocrysts in a matrix of pyroxene and glass.
- Black glass veins in Tissint contain bubbles and trace Martian atmospheric components like sulfur and fluorine, indicating weathering on Mars.
- Tissint's composition and cosmic ray exposure age of 0.7 million years are consistent with ejection from Mars during the same event as EETA79001.
- Analysis found Tissint to
This document discusses key aspects of engineering geology and its importance in modern development. It provides examples of how poor subsurface conditions, lack of safety measures, and lack of studies can lead to infrastructure failures. It emphasizes the role of engineering geology in properly studying soil and subsurface conditions before construction to select the best design and safety remedies. Methods discussed include field and laboratory investigations to understand rock quality and recommend appropriate structural support.
This document discusses a study of carbonate sedimentology and facies correlation of rocks in the Mason Mountain Wildlife Management Area in Mason, Texas. The area contains lower Cretaceous carbonate rocks from the Fort Terret formation located between the Llano Uplift igneous basement rocks and the overlying Edwards Plateau carbonates. The objective is to characterize and correlate facies within the succession based on field observations and measured sections. Understanding the depositional environments and geological processes involved in forming these rocks will provide insights into the historical development of the carbonate succession in the area.
This document summarizes a ground-penetrating radar survey of a delta front reservoir analog in the Wall Creek Member, Frontier Formation in Wyoming. It was conducted by seven authors from the University of Texas at Dallas to map the geometry and estimate sediment volumes of a top-truncated lowstand delta front. Eleven GPR profiles totaling 4,400 meters were acquired and identified four major subsurface reflections correlated with boundaries between clean sandstone and bioturbated sandstone/mudstone facies deposited during different periods. Analysis of the GPR data combined with outcrop sedimentology allowed estimation of average bar size and minimum sediment volumes as the delta migrated over time.
This field report summarizes the stratigraphy and oil trapping mechanisms of the J Sandstone in Kimball County, Nebraska. The J Sandstone consists of three members deposited in different environments: the lower J2 was deposited in shallow marine conditions, the overlying J1 indicates a transgression and was also deposited in shallow marine conditions, and the upper valley-fill member represents fluvial deposition. Stratigraphic traps within lenticular sandstone bodies and shale barriers, as well as structural traps associated with anticlines, control oil accumulation. Maps produced for this study indicate both stratigraphic and structural traps exist in the area that could be suitable for additional exploration and drilling.
Engineering geology is the application of the science of geology to the technology of ground engineering. The subject requires a comprehensive knowledge of geology, as well as an understanding of engineering properties and behaviour of the geological materials. The practice involves site investigation and site characterization specific to the needs of the engineering project. The geotechnical engineer plays a key role in most civil engineering projects as most structures are built on or in the ground. Geotechnical engineers assess the properties and behaviour of soil and rock formations.
Geoengineering Characterization of the Rock Masses of Northern Face of Jabal ...IJERA Editor
This paper is aimed at the description and the geotechnical characterization of the Tertiary granitic rock masses of the northern face of Sabir Mountain, Taiz city, Yemen, for the first time. For accomplishing this task, direct and indirect approaches are adopted. The direct approach is represented by field and laboratory investigations. Field investigations include discontinuity (joints) measurements/evaluation, applied Rock Mass Rating (RMR) system and Geological Strength Index (GSI) system, in addition to field tests, while laboratory investigations encompass physico-mechanical tests carried out on granitic rock materials. Indirect approach for the estimation of shear strength parameters (c, φ), compressive strength (σcm), tensile strength (σtm) and deformation modulus (Erm) of these rock masses was made by applying the generalized Hoek–Brown failure criterion using geotechnical Roc-Lab software. The laboratory results indicate that the Tertiary granitic rock masses show wide range of variations in their physico-mechanical characteristics owing to degree of weathering /alteration and microfractures. The intact samples of Sabir granitic (Tg) rocks show “Moderate” to “High” density, “Low” to "Medium" porosity, “Good" to "Marginal” water absorption capacity and “Weak” to “Very Strong” strength. Stereographically, three main sets of discontinuities (joints) are identified at each station; however, the fourth joint set occurs, in addition to random joint sets. The discontinuities (joints) trend predominately in NE-SW and NW-SE directions in conformity with the regional structures or faults. According to Jv j/m³ values, the degree of jointing of these rock masses are varied from “Moderate” to “High” jointing. These rocks are categorized as “Fair” to “Excellent” quality, “Fair” to “Good/Very Good” quality and “Poor” to “Very Good” quality classes according to RQD, RMR89 and GSI respectively. Values of the shear strength parameters (c and φ) and the other rock mass parameters (σtm, σc , σcm and Erm) show variations depending on the rock mass quality and properties of intact rock. However, in general the values of the rock mass parameters are found to increase with increase in the quality of rock mass and intact rock properties.
Soil and rock for geoscientist and engineersAinun Fatihah
This document summarizes key information about soils and rocks for geoscientists and engineers. It defines soil as unconsolidated mineral and organic material that forms in place and supports plant life, while rock is a solid aggregate of minerals. It describes the three main types of rocks - igneous, sedimentary, and metamorphic - and their formation processes. Several important properties of soils and rocks are also outlined, including particle size, density, porosity, plasticity, compressibility, shear strength, deformation, discontinuities, and methods for evaluating rock mass quality.
This document summarizes a study of soil geochemistry in Eruku and its environs, located in southwestern Nigeria. Twenty-five soil samples were collected and analyzed for trace element concentrations. Statistical analysis identified eleven factor groups in the data, with factors 2 and 5 related to mineralization. Isograde maps show peaks for elements like Be, Nb, Sn, and Ta in the northeast part of the study area. The study concludes that the area has anomalous concentrations of cassiterite, tantalite, and columbite hosted by pegmatites, particularly in the northeast quadrant, establishing a similar mineralization to the nearby Egbe area.
The memo discusses challenges facing the Green Bay High School Science Department and possible directions for the science curriculum. It summarizes recent changes made due to time constraints, including dropping internally assessed standards. It also discusses the need to provide students more time to assimilate course material and for practical science experiences. Finally, it proposes exploring a new educational paradigm centered around student access to online information and resources to support a more eclectic, non-linear learning experience in science.
This document provides an overview of soil mechanics as a discipline of civil engineering. It discusses the development of soil mechanics as a field systematized by Karl Von Terzaghi. The key topics covered include soil classification, compaction, soil-water relationships, stress distribution and settlement, shear strength, and slope stability. The overall objective is to impart knowledge on the physical and engineering behavior of soils, stress transfer in soils, and stability analysis of slopes. Various laboratory and field tests are also introduced to determine important engineering properties of soils.
Engineering geology involves the application of geology to construction projects. It is concerned with the rock and soil conditions of construction sites. Engineering geology provides information vital for planning, designing, and building structures like dams, bridges, and buildings. It examines the geology, geomorphology, and material properties of construction sites to understand subsurface conditions, availability of construction materials, and geologic hazards that could impact structures. Subdisciplines of engineering geology include physical geology, geomorphology, mineralogy, petrology, and economic geology. It aids in site selection, foundation design, and town planning by considering the geologic factors that influence construction and development.
This document provides an outline for a presentation on a deep-seated gravitational slope deformation in the northern Monashee Complex in British Columbia, Canada. It discusses what a DsGSD is, different approaches to studying them, and the objectives and methodology of this particular study. The study site is located near Blais Creek and exhibits characteristics like lithological weaknesses that make it prone to DsGSD. Field methods will include mapping surface features, geotechnical investigations, and trenching. Laboratory and modeling work will also be conducted to better understand the failure mechanism and incorporate the findings into an existing DsGSD database.
Kan bergartsfysikk og kvantitativ seismisk tolkning bidra til økt funnrate på...geoforskning
Rock physics provides a link between seismic data and reservoir properties by analyzing how physical rock properties affect seismic measurements. However, there are often more unknown variables than observable seismic attributes, creating a "bottleneck". Integrating rock physics with geological knowledge can help constrain non-unique interpretations. Accounting for varying rock stiffness is important, as cemented rocks may have low fluid sensitivity, making hydrocarbons difficult to detect seismically. Scale effects must also be considered, as properties vary between micro- and seismic-scales.
This document outlines the topics covered in the Engineering Geology and Seismology course. The course will discuss engineering geology, the role of geology in civil engineering, building stones, their characteristics and uses, and stone finishes. Key topics include how geology aids in foundation engineering, construction materials, and disaster mitigation. The course will also cover various building stone types like granite, sandstone, slate and marble.
Geology and groundwater quality assessment of ido osi area, southwestern nigeriaAlexander Decker
The document summarizes a study that assessed the geology and groundwater quality of the Ido/Osi area in southwestern Nigeria. Detailed geological mapping identified the dominant lithologic units as migmatites, gneisses, charnockites and granites. Water quality testing of 20 hand-dug wells found bacterial contamination above WHO standards and varying levels of physical and chemical parameters, though most were within WHO limits. The water chemistry showed moderate influence from the local bedrock. Regular monitoring is recommended given risks from contamination.
1. The document describes a research study on the mineralogical and geochemical characterization of mudrocks from the Neogene succession in Bangladesh.
2. The study will analyze mudrock samples using XRD, XRF, and laser particle size analysis to determine their depositional environments, diagenetic changes, and potential as petroleum seals or source rocks.
3. The research aims to better understand the clay mineralogy, elemental composition, grain size, and diagenetic alterations of mudrocks in two anticlines in Bangladesh and infer their depositional environments.
The foremost by-product of this paper is the automation of geological undertakings, for instance, dealing
with exceptionally thin sections of rocks that were subjected to deformation alongside finite steps of time
which can be recorded in video for later analysis using image processing and numerical analysis
procedures. Markers are used in order to trace gradients of deformation over a sample and study other
mechanical properties. Image processing and video sequence analysis can be a very powerful investigation
tool and this paper shows preliminary results from its use on microtectonics. The proposed algorithm is a
combination of two well-known approaches: feature extraction and block matching.
An application of the 2 d d.c. resistivity method in building site investigat...Alexander Decker
This study applied 2D DC resistivity methods to investigate the subsurface geology at a building site in south-south Nigeria. Two resistivity profiles identified four distinct geologic layers - a shallow clay layer, a layer of weathered rock materials, a layer of fractured basement rock, and fresh bedrock. The profiles revealed a potential geologic structure, likely a fracture, that could cause building failure if constructed across. The study concluded piles should extend to competent bedrock for major buildings, while shallow foundations can be used for small buildings, given the bedrock lies below weathered material. The integration of surface geophysics with borehole data would improve accuracy of the subsurface model.
Soil fauna and nutrient management for improving agricultural production thro...CSM _BGBD biodiversity
1) Farmers in Oumé, Côte d'Ivoire are facing decreasing soil fertility due to deforestation for cocoa and coffee farms. A study evaluated the effects of 9-month legume fallows using Pueraria phaseoloides and Cajanus cajan on soil properties, soil fauna, and subsequent maize growth.
2) The study found that legume fallows increased earthworm densities and diversity compared to a natural fallow control. Phytoparasitic nematode densities were also lower under legumes.
3) Maize yields were higher on legume fallow plots compared to the control, though not significantly for grain yield. Total biomass and 100
Geochemistry of Neogene mudrocks from Sitakund anticline, Bengal basin: Impli...Md. Yousuf Gazi
Geochemistry of Neogene mudrocks from Sitakund anticline, Bengal basin: Implications for provenance, weathering, tectonic setting and depositional environment.
This document contains 17 references related to rock mechanics and rock engineering. The references span from 1931 to 1994 and include journal articles, conference proceedings, books, theses, and reports. The references cover topics such as rock mass classification systems, shear strength of rock joints, rockfall analysis, tunnel support, and case histories of rock engineering projects.
Tissint Martian Meteorite: A Fresh Look at the Interior, Surface, and Atmosph...Carlos Bella
This document summarizes a study of the Tissint Martian meteorite that fell in Morocco in 2011. Key findings include:
- Tissint is a depleted picritic shergottite similar to meteorite EETA79001A, containing olivine macrocrysts in a matrix of pyroxene and glass.
- Black glass veins in Tissint contain bubbles and trace Martian atmospheric components like sulfur and fluorine, indicating weathering on Mars.
- Tissint's composition and cosmic ray exposure age of 0.7 million years are consistent with ejection from Mars during the same event as EETA79001.
- Analysis found Tissint to
This document discusses key aspects of engineering geology and its importance in modern development. It provides examples of how poor subsurface conditions, lack of safety measures, and lack of studies can lead to infrastructure failures. It emphasizes the role of engineering geology in properly studying soil and subsurface conditions before construction to select the best design and safety remedies. Methods discussed include field and laboratory investigations to understand rock quality and recommend appropriate structural support.
This document discusses a study of carbonate sedimentology and facies correlation of rocks in the Mason Mountain Wildlife Management Area in Mason, Texas. The area contains lower Cretaceous carbonate rocks from the Fort Terret formation located between the Llano Uplift igneous basement rocks and the overlying Edwards Plateau carbonates. The objective is to characterize and correlate facies within the succession based on field observations and measured sections. Understanding the depositional environments and geological processes involved in forming these rocks will provide insights into the historical development of the carbonate succession in the area.
This document summarizes a ground-penetrating radar survey of a delta front reservoir analog in the Wall Creek Member, Frontier Formation in Wyoming. It was conducted by seven authors from the University of Texas at Dallas to map the geometry and estimate sediment volumes of a top-truncated lowstand delta front. Eleven GPR profiles totaling 4,400 meters were acquired and identified four major subsurface reflections correlated with boundaries between clean sandstone and bioturbated sandstone/mudstone facies deposited during different periods. Analysis of the GPR data combined with outcrop sedimentology allowed estimation of average bar size and minimum sediment volumes as the delta migrated over time.
This document provides a summary of an anonymous student's education and research experience. The student received their PhD from MIT in earth and planetary sciences, focusing on high degree mantle melts. They are currently a postdoctoral researcher at MIT studying magma production in the Aleutian arc. The student has extensive experience conducting high-pressure experiments and geochemical modeling to study mantle melting processes.
Compositional Analysis of Prehistoric Shell from Eastern North AmericaMatthew T. Boulanger
http://tinyurl.com/c4oaxjz
Shell from fresh- and saltwater mussels was used throughout prehistory in eastern North America. Religious or ceremonial iconography was depicted on shell gorgets and necklaces, crushed shell was used as an additive for ceramics, and beads were fashioned from drilled fragments of shell, to name but a few uses. Hypotheses regarding the provenance—or source—of these shell artifacts have often relied on assumptions based on the modern distribution of taxa and the nearest potential source. Activation analysis of shell to determine its chemical makeup has the potential to evaluate some of these hypotheses in a manner that is un-influenced by preconceived notions of cultural influence or recent changes in the geographic range of taxa. Samples of pre-Columbian shell from archaeological deposits across the eastern U.S. are analyzed. Statistical evaluations of their compositions results in the creation of compositional groups that reflect factors of habitat and geology. Results of this study suggest that activation analysis of shell for determining provenance may provide archaeologists with a novel and exciting tool for reconstructing cultural interaction.
Sequence stratigraphy and its applicationsPramoda Raj
Sequence stratigraphy is the study of rock strata in terms of depositional sequences that are genetically related and bounded by unconformities or correlative conformities. It was pioneered by James Hutton in 1788 and further developed by researchers like Sloss and Vail to understand global eustatic sea level changes and their control on sediment deposition. Key concepts include systems tracts like transgressive, highstand, and parasequences which are building blocks of sequences. Sequence stratigraphy is useful for basin analysis, hydrocarbon exploration, and understanding past sea level fluctuations. Case studies have applied it to outcrops and subsurface sediments.
This document discusses the principles of stratigraphy used to determine the relative ages of rock layers and geological structures. It describes key stratigraphic principles like superposition, lateral continuity, inclusion and cross-cutting relationships. It also discusses methods of correlation like lithostratigraphy, chronostratigraphy and biostratigraphy which use rock characteristics, magnetic polarity or fossil evidence respectively to correlate rock formations across different locations. In conclusion, it states that stratigraphic principles are important geological tools to analyze rock sequences, estimate the order of geological events and understand field relationships.
This document discusses the rock physics of shales and source rocks. It begins by defining shale as a rock composed of mud-sized particles. Shale can have a wide range of compositions and properties depending on factors like porosity, effective stress, and organic content. The permeability of shale is very low due to its small grain size. Shale often exhibits seismic anisotropy due to thin layering of particles or organics. Organic-rich shales in particular can display large anisotropy that varies with thermal maturity. Predicting the properties of shale, especially anisotropic behavior, remains challenging due to complexity and limited data.
The integrated study characterized the reservoir quality and stratigraphy of the Mowry Shale and Muddy Sandstone in the Powder River Basin. Five depositional facies were identified in the Muddy Sandstone based on core and well log analysis, with the cleanest reservoir sands found in tidal inlet and channel deposits. The overlying Mowry Shale consisted of three parasequences deposited in a restricted shelf environment. Seismic inversion and lithofacies modeling were used to map the facies distributions across the 3D seismic volume. The results provide insights into the stratigraphic framework and reservoir characteristics of the two plays to better assess their exploration potential.
This document discusses stratigraphy and related geological concepts. It begins by outlining the contents of stratigraphy, including principles of sequence stratigraphy, sedimentary basins, models in sedimentary geology, and applied sedimentary geology. It then discusses key stratigraphic concepts like lithostratigraphy, chronostratigraphy, and biostratigraphy. Finally, it covers principles of correlation, criteria for stratigraphic classification, and elements of correlation like time units, rock units, and correlation methods involving lithological, biostratigraphic, and radioactive dating controls.
This document provides an introduction to analyzing lake sediment cores to study past climate change. It discusses why lake sediments are useful climate archives, as they form layers over time that record environmental changes. The document outlines how scientists describe and analyze sediment cores to develop climate histories. This includes taking high-resolution images, measuring properties like magnetic susceptibility, and defining different sediment facies that indicate past conditions. The goal is to characterize changes in climate and the landscape over time to better understand dynamics and improve future predictions.
Prompt What is the goal of education How successful is Ameri.docxamrit47
Prompt:
What is the goal of education? How successful is America’s educational system at achieving that goal for all of this nation’s children? Examine these questions through two in-class texts and one outside source.
Assignment Requirements:
1. You must have a clearly defined main point (thesis). The purpose of the paper is not to tell a story. Rather, use the readings and your analysis to prove a point or argue an idea.
2. For this paper you must examine the ideas of two readings from this unit and one outside source.
a. In-class readings: The authors all write about the education in some manner. You will choose two writers who help you address your thesis.
b. Outside source: A source not discussed in class that portrays or examines education. Consider consulting:
i. the media (movies, television, advertisements, etc.).
ii. magazines or newspaper articles
iii. appropriate internet sites
iv. journals (available through the library’s website)
3. You must include a minimum of six quotes from your sources, but make sure these references are relevant to your essay. Be sure to give distinctive details, descriptions, explanations, etc.
4. You must write about an issue, an idea, and not primarily about your personal experiences.
a. You may draw on personal knowledge to exemplify a point—indeed, that can be wonderful and effective‐‐, but your personal story should not take up the bulk of your essay.
5. Your paper should be five to eight pages typed, double spaced, 12 pt. Times New Roman font and have one inch margins all the way around. Your essay must also have an original title.
6. You must use MLA format/conventions for in- text citations and work cited page.
7. All final drafts of essays must be submitted onto turnitin.com by the due date. A printed copy of the essay must also be given to the instructor in class on the day due.
IN CLASS READING:
“Still Unequal, Still Separate” by Jonathan Kozol
“Report of the Massachusetts Board of Education” by Horace Mann
6 Quotations in total.
OUTSIDE SOURCE:
http://www.nytimes.com/roomfordebate/2015/05/04/is-testing-students-the-answer-to-americas-education-woes
Geology
doi: 10.1130/G31017.1
2010;38;1067-1070Geology
G.C. Koteas, M.L. Williams, S.J. Seaman and G. Dumond
Granite genesis and mafic-felsic magma interaction in the lower crust
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This document introduces rock physics concepts for interpreting seismic data. It discusses how rock physics is needed to properly interpret a seismic reflectivity map over a submarine fan. While sedimentology allows initial interpretation, well control showed clean uncemented sands had similar impedance as shales. Rock physics was needed to understand how slight cementation and poor sorting influenced impedance. The document reviews basic rock physics concepts, noting a common mistake is using overly stiff velocity-porosity relations that ignore key sedimentological variations. It introduces the concept of elastic bounds to describe effective moduli of rock mixtures.
1. The document discusses determining seismic velocities and dynamic properties of rock samples from the Balambo formation in Azmar Mountain, northern Iraq. Six rock samples were chosen and tested using an ultrasonic device to obtain P-wave and S-wave velocities.
2. Physical properties like density, bulk modulus, Young's modulus, Poisson's ratio, and anisotropy were measured. Mathematical and statistical relationships between the properties were determined, with most being directly proportional.
3. The sample with the highest marly content had the highest bulk modulus and lowest S-wave velocity, while the sample with calcite veins had the highest P-wave and S-wave velocities. The research aims to understand rock strength in the area
CORRELATION-OF-ROCK-LAYERS ELS GRADE 12.pptxJohnKennethPea
Geologists correlate rock layers between different locations by matching characteristics like composition, texture, fossils, and stratigraphic position. Correlation allows geologists to reconstruct a complete geological record even when no single location preserves a full, continuous sequence of rock layers due to erosion or gaps in deposition. Key methods of correlation include comparing rock types and index fossils, and applying principles like superposition and lateral continuity to match layers between columns. Matching correlated layers establishes their relative ages and allows geologists to estimate the original geographic extent of ancient rock units.
This document discusses the provenance of quartz arenite sandstones from the early Paleozoic midcontinent region of the USA. The authors present new detrital zircon geochronology data from 15 Cambrian and Ordovician quartz arenite samples. They compare this to existing data from older sedimentary basins in the region, including the Huron basin and midcontinent rift deposits. Mixing models using the older basin zircon populations indicate the early Paleozoic sandstones represent mixtures derived primarily from erosion of these two source areas.
The document discusses depositional models for coal exploration and mine planning in the Appalachian region. It finds that the depositional environment of coal beds strongly influences characteristics like thickness, continuity, roof conditions, and coal quality. Coals formed in back-barrier environments tend to be thin, discontinuous, high in sulfur, and have severe roof problems. Coals in the lower delta plain are more widespread but also thin and show irregular sulfur distribution. Coals in the upper delta plain-fluvial environment are thicker, lower in sulfur, but often discontinuous. Most important coals in the region formed in the transitional zone between the lower and upper delta plains, where coals can be thick and laterally continuous with low
The document summarizes findings from studying asteroid 4 Vesta using data from NASA's Dawn spacecraft. It finds that Vesta has experienced a violent collisional history, with large impacts creating steep slopes and resurfacing much of the surface. While no unambiguous volcanic deposits were found, some dark material in impact craters may be from excavated subsurface volcanic features. Smooth ponds found on Vesta are also seen on asteroid Eros and are thought to form from impact ejecta collecting in depressions.
This document proposes a new method for rapidly assessing the age of geological units on Mars using measurements of topographic roughness. It hypothesizes that roughness will be correlated with age derived from crater size-frequency distributions, as craters increase surface roughness over time. To test this, the author analyzes topography images and measures roughness from 125 sites across Mars. Age is calculated from crater counts and compared to roughness measurements. Preliminary results show a significant relationship between some roughness measures and age, though there is also variation likely due to crater degradation processes altering roughness without affecting size distributions. If validated, roughness could provide a faster way to assess relative Martian surface ages than traditional crater counting.
Philippine Edukasyong Pantahanan at Pangkabuhayan (EPP) CurriculumMJDuyan
(𝐓𝐋𝐄 𝟏𝟎𝟎) (𝐋𝐞𝐬𝐬𝐨𝐧 𝟏)-𝐏𝐫𝐞𝐥𝐢𝐦𝐬
𝐃𝐢𝐬𝐜𝐮𝐬𝐬 𝐭𝐡𝐞 𝐄𝐏𝐏 𝐂𝐮𝐫𝐫𝐢𝐜𝐮𝐥𝐮𝐦 𝐢𝐧 𝐭𝐡𝐞 𝐏𝐡𝐢𝐥𝐢𝐩𝐩𝐢𝐧𝐞𝐬:
- Understand the goals and objectives of the Edukasyong Pantahanan at Pangkabuhayan (EPP) curriculum, recognizing its importance in fostering practical life skills and values among students. Students will also be able to identify the key components and subjects covered, such as agriculture, home economics, industrial arts, and information and communication technology.
𝐄𝐱𝐩𝐥𝐚𝐢𝐧 𝐭𝐡𝐞 𝐍𝐚𝐭𝐮𝐫𝐞 𝐚𝐧𝐝 𝐒𝐜𝐨𝐩𝐞 𝐨𝐟 𝐚𝐧 𝐄𝐧𝐭𝐫𝐞𝐩𝐫𝐞𝐧𝐞𝐮𝐫:
-Define entrepreneurship, distinguishing it from general business activities by emphasizing its focus on innovation, risk-taking, and value creation. Students will describe the characteristics and traits of successful entrepreneurs, including their roles and responsibilities, and discuss the broader economic and social impacts of entrepreneurial activities on both local and global scales.
Leveraging Generative AI to Drive Nonprofit InnovationTechSoup
In this webinar, participants learned how to utilize Generative AI to streamline operations and elevate member engagement. Amazon Web Service experts provided a customer specific use cases and dived into low/no-code tools that are quick and easy to deploy through Amazon Web Service (AWS.)
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إضغ بين إيديكم من أقوى الملازم التي صممتها
ملزمة تشريح الجهاز الهيكلي (نظري 3)
💀💀💀💀💀💀💀💀💀💀
تتميز هذهِ الملزمة بعِدة مُميزات :
1- مُترجمة ترجمة تُناسب جميع المستويات
2- تحتوي على 78 رسم توضيحي لكل كلمة موجودة بالملزمة (لكل كلمة !!!!)
#فهم_ماكو_درخ
3- دقة الكتابة والصور عالية جداً جداً جداً
4- هُنالك بعض المعلومات تم توضيحها بشكل تفصيلي جداً (تُعتبر لدى الطالب أو الطالبة بإنها معلومات مُبهمة ومع ذلك تم توضيح هذهِ المعلومات المُبهمة بشكل تفصيلي جداً
5- الملزمة تشرح نفسها ب نفسها بس تكلك تعال اقراني
6- تحتوي الملزمة في اول سلايد على خارطة تتضمن جميع تفرُعات معلومات الجهاز الهيكلي المذكورة في هذهِ الملزمة
واخيراً هذهِ الملزمة حلالٌ عليكم وإتمنى منكم إن تدعولي بالخير والصحة والعافية فقط
كل التوفيق زملائي وزميلاتي ، زميلكم محمد الذهبي 💊💊
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THE SACRIFICE HOW PRO-PALESTINE PROTESTS STUDENTS ARE SACRIFICING TO CHANGE T...indexPub
The recent surge in pro-Palestine student activism has prompted significant responses from universities, ranging from negotiations and divestment commitments to increased transparency about investments in companies supporting the war on Gaza. This activism has led to the cessation of student encampments but also highlighted the substantial sacrifices made by students, including academic disruptions and personal risks. The primary drivers of these protests are poor university administration, lack of transparency, and inadequate communication between officials and students. This study examines the profound emotional, psychological, and professional impacts on students engaged in pro-Palestine protests, focusing on Generation Z's (Gen-Z) activism dynamics. This paper explores the significant sacrifices made by these students and even the professors supporting the pro-Palestine movement, with a focus on recent global movements. Through an in-depth analysis of printed and electronic media, the study examines the impacts of these sacrifices on the academic and personal lives of those involved. The paper highlights examples from various universities, demonstrating student activism's long-term and short-term effects, including disciplinary actions, social backlash, and career implications. The researchers also explore the broader implications of student sacrifices. The findings reveal that these sacrifices are driven by a profound commitment to justice and human rights, and are influenced by the increasing availability of information, peer interactions, and personal convictions. The study also discusses the broader implications of this activism, comparing it to historical precedents and assessing its potential to influence policy and public opinion. The emotional and psychological toll on student activists is significant, but their sense of purpose and community support mitigates some of these challenges. However, the researchers call for acknowledging the broader Impact of these sacrifices on the future global movement of FreePalestine.
A Visual Guide to 1 Samuel | A Tale of Two HeartsSteve Thomason
These slides walk through the story of 1 Samuel. Samuel is the last judge of Israel. The people reject God and want a king. Saul is anointed as the first king, but he is not a good king. David, the shepherd boy is anointed and Saul is envious of him. David shows honor while Saul continues to self destruct.
How Barcodes Can Be Leveraged Within Odoo 17Celine George
In this presentation, we will explore how barcodes can be leveraged within Odoo 17 to streamline our manufacturing processes. We will cover the configuration steps, how to utilize barcodes in different manufacturing scenarios, and the overall benefits of implementing this technology.
This document provides an overview of wound healing, its functions, stages, mechanisms, factors affecting it, and complications.
A wound is a break in the integrity of the skin or tissues, which may be associated with disruption of the structure and function.
Healing is the body’s response to injury in an attempt to restore normal structure and functions.
Healing can occur in two ways: Regeneration and Repair
There are 4 phases of wound healing: hemostasis, inflammation, proliferation, and remodeling. This document also describes the mechanism of wound healing. Factors that affect healing include infection, uncontrolled diabetes, poor nutrition, age, anemia, the presence of foreign bodies, etc.
Complications of wound healing like infection, hyperpigmentation of scar, contractures, and keloid formation.
Elevate Your Nonprofit's Online Presence_ A Guide to Effective SEO Strategies...TechSoup
Whether you're new to SEO or looking to refine your existing strategies, this webinar will provide you with actionable insights and practical tips to elevate your nonprofit's online presence.
BIOLOGY NATIONAL EXAMINATION COUNCIL (NECO) 2024 PRACTICAL MANUAL.pptx
Makowitz et al_2006
1. GEOLOGIC NOTE AUTHORS
A. Makowitz $ Department of Geological
Diagenetic modeling to assess Sciences, University of Texas at Austin, Austin,
Texas 78712; present address: BP America, 501
Westlake Park Blvd., Houston, Texas 77079;
the relative timing of quartz Astrid.Makowitz@BP.com
Astrid Makowitz joined BP upon completion of her
cementation and brittle grain Ph.D. at the University of Texas at Austin (2004).
Both M.S. (1999) and B.S. (1997) geology degrees
processes during compaction were awarded from the Michigan State University.
Astrid has enjoyed working as a reservoir quality
specialist and is currently in the Onshore North
A. Makowitz, R. H. Lander, and K. L. Milliken American Gas production setting. Her love for ge-
ology remains with studying rocks on a pore to
subpore scale.
R. H. Lander $ Geocosm LLC, 3311 San Mateo
ABSTRACT Drive, Austin, Texas 78738
This study describes porosity reduction by brittle deformation and Robert Lander coinvented Geocosm’s Prism and
the application of Touchstone sandstone diagenesis modeling
TM Touchstone models and Geologica’s Exemplar1
model. Rob obtained a Ph.D. in geology from the
software to assess the relative timing and interactions between
University of Illinois in 1991 and was a senior
grain fracturing and cement formation during burial compaction. research geologist at Exxon Production Research
Two examples from a previous study of compactional fracturing are from 1990 to 1993. He then worked for Rogaland
used: the Oligocene Frio Formation, Gulf of Mexico Basin, and the Research and Geologica in Stavanger, Norway.
Cambrian Mount Simon Formation, Illinois Basin, United States. Rob cofounded Geocosm in 2000 and is a research
fellow at the University of Texas at Austin.
Grain fracturing during compaction creates intragranular fracture
surfaces that are favorable sites for quartz nucleation compared to K. L. Milliken $ Department of Geological
external grain surfaces that may bear coatings that inhibit the nu- Sciences, University of Texas at Austin, Austin,
cleation and growth of quartz cement. Thus, the progress of brittle Texas 78712
fracture processes during diagenesis affects quartz cementation. In Kitty Milliken has degrees in geology from Van-
turn, modeling of the quartz cementation process can serve to place derbilt University (B.A.) and the University of Texas
at Austin (M.A. degree, Ph.D.). At the University of
fracturing into its proper context in burial history.
Texas at Austin, she currently serves as a research
In the Mount Simon Formation, the extent of brittle deforma- scientist in the electron microbeam facility. Together
tion of quartz grains correlates with reconstructed effective stress at with students, she pursues research projects that
the onset of quartz cementation. For Frio Formation samples, how- apply imaging and analysis to decipher the chem-
ever, the extent of brittle deformation does not correlate well with ical histories of low-temperature systems. She is
reconstructed effective stress obtained using a one-dimensional basin a coauthor of the recently released interactive teach-
ing module Sandstone Petrology: A Tutorial Petro-
model that uses compaction disequilibrium as the dominant mecha-
graphic Image Atlas.
nism for overpressure generation. Judging from the observed degree
of grain fracturing, significant fluid overpressures in the Frio may not
have developed at the shallow depths indicated by our basin models. ACKNOWLEDGEMENTS
The degree of compactional fracturing in sandstones constitutes The authors are grateful to Zyihong He of Zetaware
observable evidence that can be used to decipher the complexities of for generously providing access to the Genesis
pressure history. Software. We thank Anadarko, BHPBillton, BP, Chev-
ronTexaco, ConocoPhillips, ExxonMobil, Kerr-McGee,
Petroleos de Venezuela SA, Petrobras, Saudi Aramco,
´
Shell, Total, and Unocal for supporting Touchstone
research and development by virtue of their mem-
bership in Geocosm’s Consortium for Quantitative
Copyright #2006. The American Association of Petroleum Geologists. All rights reserved. Prediction of Sandstone Reservoir Quality. Reviewers
Manuscript received March 5, 2005; provisional acceptance June 14, 2005; revised manuscript received Olav Walderhaug, Howard White, and Nick Wilson
November 15, 2005; final acceptance December 19, 2005. gave constructive suggestions for the improvement
DOI:10.1306/12190505044 of our article.
AAPG Bulletin, v. 90, no. 6 (June 2006), pp. 873 – 885 873
2. INTRODUCTION Several recent investigations conclude that the sig-
nificance of brittle deformation in mechanical compac-
Here, we undertake to integrate observations of com- tion is greater than previously thought, especially for
pactional grain fracturing with quartz cementation rapidly and deeply buried sandstones (Milliken, 1994;
modeling. Because the brittle fracturing process in com- Chuhan et al., 2002; Makowitz and Milliken, 2003).
paction creates significant new surfaces for quartz ce- Cathodoluminescence (CL) imaging reveals the ubiq-
mentation, it is reasonable to seek linkages between uity of microfractures initiating at quartz grain contacts,
these two processes (Makowitz and Milliken, 2003). where the deviatoric stress (condition in which stress
Modeling adds a vital quantitative perspective to our tensors are not the same in every direction) needed for
understanding of the timing and depth of quartz ce- brittle failure can be achieved locally, at the grain scale,
mentation (Lander and Walderhaug, 1999) and, fur- under conditions that are below the critical conditions
ther, into the relative timing of cementation and grain for crack propagation through the sandstone as a whole
fracturing in the subsurface. Forecasting brittle grain (e.g., Sippel, 1968; Walker and Burley, 1991; Milliken,
deformation influences on reservoir quality can pro- 1994; Dickinson and Milliken, 1995). The fresh micro-
vide important insights for hydrocarbon exploration, fracture creates a clean surface that is favorable for
especially in basins where deep sandstones are prolific. quartz cement nucleation (Reed and Laubach, 1996).
Quantitative data on fracture aperture, morphology,
number of fractures, and volume of cement localized
PREVIOUS WORK within these fractures can be gathered readily using CL
imaging (Laubach and Milliken, 1996; Laubach, 1997;
Compaction and cementation are the two mechanisms Marrett and Laubach, 1997; Laubach et al., 2004). In-
whereby primary porosity is lost in sandstones (e.g., herited fractures are discriminated on the basis of CL
Lundegard, 1992; Ehrenberg, 1995), and an understand- textures and excluded from measurements of post-
ing of the controls on these processes has significant compactional fractures using the criteria of Laubach
implications for predictions of reservoir quality. The (1997).
magnitude of mechanical compaction of sandstones Contrasts in the number of fractured grains per
during burial, a process including grain slippage, ro- sample versus maximum burial depth between the Frio
tation, and deformation, is controlled by the composi- and Mount Simon formations and the differences in
tion, size, and shape of the constituent grains (Pittman fracture morphology were hypothesized in a previous
and Larese, 1991) and the burial history (Lander and study to be dependent on the timing of quartz cemen-
Walderhaug, 1999; Paxton et al., 2002). Brittle pro- tation, which, in turn, is governed by burial rate and
cesses in compaction are a particularly underestimated geothermal gradient differences between the Frio (Gulf
process because intragranular fractures in quartz grains of Mexico Basin) and the Mount Simon (Illinois Basin),
are typically healed by quartz cement and are therefore together with compositional and textural differences
difficult to detect and measure and are commonly (e.g., Frio samples have lower quartz grain content and
missed using conventional transmitted light micros- larger grain size) (Makowitz and Milliken, 2002, 2003).
copy (e.g., Sippel, 1968; Milliken, 1994; Dickinson and These earlier studies also discuss in detail the evidence
Milliken, 1995; Makowitz and Milliken, 2003). for the postburial timing of the intragranular fracturing
Cementation hinders mechanical compaction; thus, and its compactional association, correlations between
information on the timing and physical properties of the degree of fracturing and grain size, and the para-
cement phases is necessary for predicting the extent genetic sequence of cements in these sandstones.
of mechanical compaction (Ehrenberg, 1989; Pittman
and Larese, 1991; Lundegard, 1992; Wilson and Stanton,
1994; Dutton, 1997; Stone and Siever, 1997; Lander GEOLOGIC CONTEXT AND PETROGRAPHY
and Walderhaug, 1999; Paxton et al., 2002). Conversely, OF BRITTLE FEATURES
the intergranular volume (‘‘IGV’’ is defined as the sum
of the intergranular porosity and cements and matrix Frio Formation
that fill intergranular pores) remaining at a particular
stage in the burial history places an upper limit on the The Oligocene Frio Formation sandstone has long served
amount of space that is available for cement emplace- as a natural laboratory for studying burial compaction
ment at a given depth (e.g., Paxton et al., 2002). because more than 3500 m (11,400 ft) of sediment was
874 Geologic Note
3. Sample Location Figure 1. Sample location map. The
Frio Formation was sampled from core
from various depths in the south Texas
Gulf Coast. Samples from the Mount
Simon Formation were collected from
A core and outcrop localities in the
Illinois Basin.
Illinois
Illinois
Basin
Basin Aí
B
Bí
Gulf Coast
rapidly deposited via subsidence and growth faulting erally confined to individual grains (intragranular frac-
during the middle to late Oligocene and early Miocene tures) and do not transect two or more grains (trans-
(e.g., Galloway et al., 1982) (Figure 1). Moreover, the granular fracturing).
structural history does not involve significant uplift Quartz cementation is expected to stabilize the
or compression, the unit is at or near maximum buri- grain framework and thereby inhibit compactional grain
al depth, and growth faults impose a wide range of fracturing. Cathodoluminescence textures indicate that
burial depths and temperatures on materials of rela- most fractures precede significant cementation, given
tively uniform initial composition. The predominantly that most do not crosscut overgrowths (Figure 3). The
lithic-rich sands of the Frio Formation of the lower minority of fractures that do crosscut overgrowths
Gulf Coast were supplied by the ancient Rio Grande (see Makowitz and Milliken, 2003, their figure 10E,
draining the volcanic areas of west Texas and northern p. 1015) shows, however, that grain fracturing and
Mexico (Loucks et al., 1984). Frio sandstones are mod- quartz cementation proceed synchronously, at least
erately sorted, fine to coarse grained, and range from to some degree. Shallowly buried quartz grains exhib-
feldspathic litharenites to sublitharenites (Figure 2). iting intragranular grain fractures are generally filled
Although quartz cement is dominant in most samples, with quartz cement but lack cementation on external
for any given set of samples, there will be a few that grain surfaces (Figure 4), indicating faster surface area-
are dominantly calcite cemented. Zeolite cement is normalized growth rates on fracture surfaces com-
abundant at shallow depths (maximum = 10%), asso- pared to outer grain surfaces. The fracture surface is
ciated with volcanic-derived lithics, whereas quartz fresh and clean, allowing quartz cement to nucleate
cement generally increases systematically with depth and grow within the fracture, whereas the external
(Land, 1984; Land et al., 1987), as is widely observed grain surface may contain irregularities and detrital
in many basins worldwide (e.g., Walderhaug, 1996; particles that slow the rate of quartz precipitation.
Giles et al., 2000).
Quartz grains in the Frio Formation have a variety Mount Simon Formation
of fracture morphologies, including wedge-shaped aper-
tures, intense comminution at grain contacts, and grains The Illinois Basin is an intracratonic basin in which up
with exploded fabrics (Makowitz and Milliken, 2002, to 6000 m (19,600 ft) of sediments accumulated dur-
2003) (Figure 3A, B). Apparent fracture apertures in ing the Paleozoic (Figure 1). The Mount Simon sand-
the Frio grains are slightly wider (average 5 mm) than stones (Late Cambrian) are predominantly of quartz
in Mount Simon grains (average measurable aperture arenite composition, medium to coarse grained, and
width $4 mm). Fractures in both formations are gen- well rounded (Figure 2). Quartz is the most abundant
Makowitz et al. 875
4. Figure 2. Ternary plot
of sandstone composi-
tions according to Folk’s
(1980) classification
scheme. Plot shows the
variation of sandstone
composition between the
Mount Simon and Frio
formations. Average
compositions of the Frio
and Mount Simon for-
mations are feldspathic
and quartz arenite,
respectively.
cement, although calcite is locally abundant in shal- in the northerly area. Maximum burial depths of sam-
low samples. During the Late Cambrian, the tectonic ples for this study are based on the model results of
setting of the proto-Illinois Basin was governed by Rowan et al. (2002). Their model considers the tem-
thermal subsidence, lasting until the early Mississippi- perature influence of burial (considered the most in-
an (Rowan et al., 2002). A second subsidence episode fluential factor for temperature in past models) and
(middle Mississippian through Early Permian), in re- advective heat transport from a short period of mag-
sponse to the Alleghanian –Hercynian orogeny (Klein matism and is consistent with both vitrinite reflectance
and Hsui, 1987), caused pronounced downwarping in and fluid-inclusion data.
the more southerly parts of the basin, leading to thicker Fracture morphologies in the Mount Simon For-
sediment accumulation (Sargent, 1991). mation are homogenous and occur as thin straight
Other tectonic events that effected Mount Simon traces transecting across the quartz grains. A few wedge-
deposition included periodic uplift on bounding arches shaped fractures are also present in some samples
(e.g., Wisconsin, Kankawee, and Pascola arches) that (Figure 3).
separate the Michigan basin from the Illinois Basin.
Coal rank and two-dimensional burial-history models
calibrated to coal vitrinite reflectance and biomarkers
suggest that maximum burial was attained during the MODELING APPROACH
Permian, approximately 1000–1500 m (3300–4900 ft)
deeper than present (Rowan et al., 1996; Damberger Basin Modeling
et al., 1999). During the Quaternary, glacial outwash
was deposited over most of the Illinois Basin. Amounts Basin modeling was conducted using Genesis1 (devel-
of uplift and erosion in the Illinois Basin vary, with up oped by Zetaware) to reconstruct the thermal and ef-
to 2000 m (6600 ft) in the south and approximately fective stress histories of the analyzed samples. Data
300 m (1000 ft) in the north (Hoholick, 1980). Other for the one-dimensional (1-D) basin models were re-
estimates of burial depth provided by Wilson and Sib- trieved from well logs, including mud weights, bottom-
ley (1978) indicate nearly 900 m (2900 ft) of erosion hole temperatures, circulation times, stratigraphy, and
876 Geologic Note
5. Figure 3. Fracture
styles and morphologies
characteristic of the Frio
(A and B) and Mount
Simon quartz grains
(C and D). Fractures in
the Frio Formation (A and
B) are commonly wedge
shaped, exhibit spalling,
and commonly have
small-scale cataclasis as-
sociated with grain-grain
contacts. In the Mount Si-
mon Formation, fractures
generally transect the
quartz grains as straight
traces with fracture
apertures more uniform
and generally thinner
than in the Frio.
gross lithology for the Frio Formation. Although vi- derhaug, 1999; de Souza and McBride, 2000; Walder-
trinite reflectance data are scarce, when available, they haug, 2000; Bloch et al., 2002; Bonnell and Lander,
were used to constrain thermal histories. Where in- 2003; Taylor et al., 2004) or for constraining thermal
put data were not available for some of the wells, histories (Awwiller and Summa, 1997, 1998; Lander
we estimated the values by interpolation with nearby et al., 1997a, b; Perez et al., 1999). Such models, how-
wells. ever, also have the potential to provide improved tem-
Although most of the modeled temperatures match poral constraints on the diagenetic evolution of sand-
within ± 5jC of measured temperatures, a substantial stones (Bonnell et al., 1999; Helset et al., 2002). In
number of measurements fall out of this range. In most this study, we use Touchstone version 6.0 to constrain
cases, measured temperatures are lower than modeled the history of quartz cementation, so that we can bet-
temperatures. Most likely, the true temperatures are ter delineate the precise timing and conditions of brit-
higher than the measured values because of the effects tle grain deformation relative to cement emplacement.
of drilling. Bottom-hole temperature data retrieved Model inputs include (1) textural and compositional
from well logs match other such data from south Texas characteristics of each analyzed sample; (2) thermal
(e.g., McKenna and Sharp, 1998). and effective stress histories derived from basin mod-
Mount Simon Formation burial history data are eling; and (3) and various model parameters discussed
from the model of Rowan et al. (2002) for the burial below. We used the same model parameters for all
history of the intracratonic Illinois Basin (Figure 5). simulations with two important exceptions where pa-
rameters were optimized to match measurements: the
Simulation of Quartz Cementation History activation energy for quartz precipitation (E a) and the
stable packing arrangement (IGVf).
Sandstone diagenesis and reservoir quality models Following Walderhaug (1994, 1996), we assume that
such as Exemplar (Lander and Walderhaug, 1999) or
TM
the rate-limiting control on quartz cementation is the
Touchstone typically are used for reservoir quality
TM
rate of crystal growth and not the rate of silica supply. The
prediction (e.g., Bonnell et al., 1999; Lander and Wal- surface area-normalized rate of quartz precipitation, k,
Makowitz et al. 877
6. function of time and temperature using thermal re-
constructions from basin models. We adjust the E a
value for each sample simulation to achieve a match
between the calculated and measured quartz cement
abundances for each individual sample ( Table 1). The
adjusted E a values for a given stratigraphic unit gen-
erally fall within a narrow range.
An additional important control on quartz cemen-
tation is the nucleation surface area and how it changes
with diagenetic alteration. We follow an approach sim-
ilar to that of Lander and Walderhaug (1999), but as-
sume that cements concentrically line spherical pores
(Merino et al., 1983; Lichtner, 1988; Canals and Meunier,
1995). The timing of nonquartz cement precipitation
is defined by paragenetic rules and burial history re-
constructions as shown in Table 2.
Compaction reduces intergranular porosity and
therefore may reduce surface area for quartz cement
nucleation. The compaction state of the sample is de-
termined using the function of Lander and Walderhaug
(1999):
IGV ¼ IGVf þ ðIGVo À IGVf ÞÀbse
where IGVf is a stable packing arrangement that rep-
resents the minimum likely intergranular volume (%);
IGVo is the intergranular volume upon deposition (%),
and b is the exponential rate of compaction (MPa À 1)
with effective stress se (MPa). The compaction state
Figure 4. Frio sample 3223 (A) scanning electron microscopy- of the sample is determined through geologic time as
cathodoluminescence image of grain exhibiting fractures filled the effective stress (from basin modeling) changes, al-
with quartz cement. (B) Secondary electron image (SEI) show- though the compaction process is assumed to be ir-
ing continuous smooth surface of grain, indicating that frac- reversible should effective stress decline (Lander and
tures are filled with quartz. Two possible reason for this pref- Walderhaug, 1999). IGVo is determined using a pro-
erential fracture annealing: (1) clays and byproducts from prietary algorithm in Touchstone that is based on the
dissolved grains (partially dissolved feldspar in upper left and unpublished experimental work of R. E. Larese and L.
corner) adhered to the detrital grain surface and prohibited M. Bonnell, and a constant value of 0.6 MPa À 1 is used
quartz precipitation around the grain and (2) low temperatures for b as suggested by Lander and Walderhaug (1999).
at this depth ($50jC) make it difficult for quartz cement to The IGVf value for each sample (Table 1) provides an
precipitate.
optimal match between the present-day calculated and
measured IGV values. These values vary considerably
is modeled using an Arrhenius kinetic formulation among samples because of differences in the extent of
(Walderhaug, 1996): grain deformation and chemical compaction.
ÀEa
k ¼ Ao e RT
MODELING RESULTS
where E a is the activation energy for quartz precipi-
tation (kJ/mol); R is the universal gas law constant To evaluate the potential influence of quartz cemen-
(8.31 J/mol K); T is temperature (K); and A o is the tation on fracture characteristics, we used Touch-
pre-exponential constant (here taken to be 9 Â 10 À 12 stone simulations to reconstruct the burial conditions
mol/cm2 s). The kinetic equation is integrated as a at which small amounts of quartz cement (0.5, 1, and
878 Geologic Note
7. Figure 5. Thermal history for Frio and Mount Simon formations generated from 1-D Genesis basin models. Frio wells are depicted
by name and are located in the following south Texas counties: (1) Jack Brown in Live Oak Co.; (2) Slick State in Starr Co.; (3) Baffin
State in Kleberg Co.; (4) Hornsby in Brooks Co.; (5) Seeligson and McHaney in Jackson Co.; (6) Gerdts and McCullough in Willacy Co.;
(7) Copano State in Aransas Co.; and (8) Pleasant Bayou in Brazoria Co.
2%) formed in the analyzed samples ( Table 1). Our of quartz precipitation. Differences in the surface area
results show wide ranges in conditions. For example, for quartz nucleation are an additional cause of varia-
the reconstructed burial depth at which 2% quartz tion in quartz cement abundances. Mount Simon For-
cement formed ranges from approximately 1700 to mation sandstones generally would be expected to have
2600 m (5500 to 8500 ft) in Mount Simon samples somewhat more quartz cement than Frio Formation
compared to about 2650 – 4400 m (8690 – 14,435 ft) samples of comparable grain size and thermal exposure
in Frio Formation samples (Figure 6A). These differ- because of greater nucleation surface associated with
ences mainly reflect variations in the thermal histories greater quartz grain abundance and lower grain coating
among the analyzed samples. Thermal history is im- coverage.
portant because modeled quartz precipitation rates The percentage of fractured quartz grains corre-
increase nearly exponentially with temperature, where- lates strongly with the reconstructed burial depth at
as at a given temperature, the amount of quartz cement the time small amounts of quartz cementation formed
increases nearly linearly with time. Sandstones with rap- for samples from both data sets (Figure 6). This cor-
id burial rates, therefore, tend to be more deeply buried relation appears to be somewhat stronger for the depth
by the time a small amount of quartz cement forms at which 2% quartz formed than it is for 1 or 0.5%
because they have lower residence times at shallow (Figure 6A, B). Burial depth is a driving force for com-
depths, where temperatures are cooler. Such samples paction, however, only in as much as it relates to effec-
also tend to experience significant quartz cementa- tive stress (and temperature when it involves chem-
tion at earlier times given that they have earlier ex- ical processes). In the Frio Formation our 1-D basin
posure to higher temperatures that lead to faster rates models indicate that those samples with the greatest
Makowitz et al. 879
9. Table 2. Depth Constraints for the Paragenetic Sequence
37.0
34.1
32.0
32.6
51.2
52.0
Used in Modeling for Both the Frio and Mount Simon
*
Formations
9.9
8.3
7.9
8.1
34.6
31.2
*
Start (m) End (m)
2962.7
2729.3
2557.5
2611.1
4098.1
4156.5
Grain coating 0 100
*
Calcite 100 1000
Chlorite 200 1000
96.7
100.2
105.2
107.1
156.5
159.5
Kaolinite 1000 2000
*
Pyrite 0 100
K-feldspar 1000 3000
15.37
20.82
24.45
23.7
24.6
Dolomite 2000 4000
0
*
Iron oxides 100 1000
36.5
33.4
32.7
54.6
54.6
*
*
reconstructed burial depths at the time of significant
9.4
8.5
8.6
33.6
11.9
quartz cementation also have the lowest reconstructed
*
*
effective stresses because they experienced faster rates
2917.6
2668.4
2615.7
4366.5
4370.7
of burial and, therefore, greater extents of fluid over-
*
*
pressure development because of compaction disequi-
librium (caused by the inability to expel pore fluids
100.5
106.7
107.9
170.6
172.5
*
*
in low-permeability shales and clay-rich sediments;
hence, most of the overlying sediment’s weight is
16.01
21.78
23.44
supported by the pore fluid instead of the grains)
5.3
23.7
*
*
(Figure 7). Thus, the Frio Formation samples with
the greatest degree of quartz grain fracturing also had
the lowest reconstructed effective stresses at the time
37.0
33.7
54.5
54.5
*
*
*
of significant quartz cementation. Such a result is in-
consistent with experimental and theoretical results,
*Samples with less than 2% quartz cement that we were not able to model or are insignificant.
14.6
11.1
which indicate that grain fracturing is promoted by
9.0
9.1
*
*
*
greater effective stresses (Chuhan et al., 2002; Chester
2956
2693
4357
4363
et al., 2004; Karner et al., 2005). The extent of grain
*
*
*
fracturing correlates much more strongly with effec-
tive stress if fluid pressures were near hydrostatic lev-
113.7
108.3
177.2
177.6
*
*
*
els at the time that small amounts of quartz cement
formed (hydrostatic case in Figure 7). These results
7
18
23
22
suggest that fluid overpressures in the Frio Formation
*
*
*
may have developed at significantly greater depths (and
7.2
25.3
14.1
26.6
11.3
17.5
16.7
later times) than would be expected in basin models
38.0
38.8
36.7
37.2
43.1
32.5
35.1
that rely mainly on compaction disequilibrium. Alter-
native mechanisms for fluid overpressure development
61.0
62.5
58.7
58.2
63.4
63.3
*
that could lead to a shift into overpressured conditions
late in the burial history include hydrocarbon reac-
tions (Luo and Vasseur, 1996; Osborne and Swarbrick,
Frio
Frio
Frio
Frio
Frio
Frio
Frio
1997; Hansom and Lee, 2005) and diagenetic reac-
Pleasant Bayou
Pleasant Bayou
tions (Waples and Kamata, 1993; Bjørkum and Nadeau,
McCullough
1996, 1998; Lander 1998; Matthews et al., 2001; Helset
McHaney
McHaney
McHaney
et al., 2002).
Gerdts
As discussed previously, fractures in the Mount
Simon Formation samples show thin-straight fracture
10169
13833
15620
15640
9710
9720
9744
traces, whereas in Frio Formation samples, fractures
Makowitz et al. 881
10. Figure 6. Depths at which quartz cement content reached 0.5% (A) and 2% (B) versus percentage of fractured quartz grains. A
positive correlation exists between the onset of quartz cementation and degree of grain fracturing for both the Mount Simon and Frio
formations, and this correlation is best for the 2% level of quartz cement emplacement.
have larger wedgelike forms. The difference in the Mount Simon Formation samples had more restricted
effective stress at the onset of significant quartz ce- dilation because of their greater abundance of rigid
mentation may be one factor causing this change in quartz grains or their lower IGV values (average of
fracture geometry. It is also possible that fractures in 18.6 versus 24.8% for the Frio).
Figure 7. Effective stress at low amount of quartz cement, (A) at 0.5% quartz cement and (B) at 2.0% quartz cement, versus
percentage of fractured grains shows a positive correlation in both formations, considering a hydrostatic stress regime at this time in
the burial history. However, if deeper Frio sands are influenced by compaction disequlibrium, which causes overpressure, thus,
reducing the effective stress, this trend would not hold true.
882 Geologic Note
11. CONCLUSIONS Chuhan, F. A., A. Kjeldstad, K. Bjørlykke, and K. Høeg, 2002, Po-
rosity loss in sand by grain crushing — Experimental evidence
and relevance to reservoir quality: Marine and Petroleum Geol-
Data presented in this article demonstrate that the ogy, v. 19, p. 39 – 53.
effective stress at the time of quartz cement Damberger, H. H., I. Demir, and J. Pine, 1999, Age relationships
between coalification, deformation, and geothermal events in
initiation is an important constraint for predicting
the Illinois Basin (abs.): Geological Society of America Annual
the degree of grain fracturing in quartz-rich sands. Meeting Program, p. 403.
The deeper Frio data support the notion that ef- de Souza, R. S., and E. F. McBride, 2000, Diagenetic modeling and
fective stresses were much higher than would be reservoir quality assessment and prediction: An integrated
approach (abs.): AAPG Bulletin, v. 84, no. 9, p. 1495.
expected from 1-D disequilibrium compaction mod- Dickinson, W. W., and K. L. Milliken, 1995, Diagenetic role of
els at the time of quartz cement initiation, suggesting brittle deformation in compaction and pressure solution, Etjo
that overpressure began at greater depths (later Sandstone, Namibia: Journal of Geology, v. 103, p. 339 –
347.
times) in the burial history. Dutton, S. P., 1997, Timing of compaction and quartz cementa-
Differences in degree of fracturing and fracture mor- tion from integrated petrographic and burial history analysis,
phologies between the Frio and Mount Simon for- Lower Cretaceous Fall River Formation, Wyoming and South
Dakota: Journal of Sedimentary Research, v. 67, p. 186 –
mations can be attributed to (1) greater depth to
196.
initiation of quartz cementation in the Frio than in Ehrenberg, S. N., 1989, Assessing the relative importance of
the Mount Simon, allowing for more and wider frac- compaction processes and cementation to reduction of poros-
ity in sandstones: Discussion: AAPG Bulletin, v. 73, p. 1274 –
tures and apertures in the Frio; and (2) IGV, whereby
1276.
lower IGVs in the Mount Simon resulted in a re- Ehrenberg, S. N., 1995, Measuring sandstone compaction from
duced possibility of expansion of grains into the pore modal analysis of thin sections: How do I do it and what do the
space and, hence, thinner fracture apertures. results mean: Journal of Sedimentary Research, v. A65, p. 369 –
379.
Folk, R., 1980, Petrology of sedimentary rocks: Austin, Texas,
Hemphill Publishing Company, 170 p.
Galloway, W. E., D. K. Hobday, and K. Magara, 1982, Frio
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