Geophysical methods such as well logs and seismic studies are used to correlate and map rock layers where there is no surface exposure. Well logs record information from probes in boreholes, measuring properties like density, permeability, and pore fluid content. Seismic studies involve generating sound waves that reflect off subsurface interfaces, allowing approximation of rock layer geometry. These remote techniques provide data to interpret stratigraphy where direct observation is not possible.
The document summarizes the analysis of layered deposits inside the 174 km diameter Terby impact crater located on Mars. Stratigraphic and mineralogical analysis using multiple datasets suggests the deposits were formed subaqueously during the Noachian period. The thickest sequences display fan delta morphologies indicative of prograding/onlapping sedimentation over time. Phyllosilicates detected within layers support a sedimentary environment with sustained liquid water. Erosion during the Hesperian sculpted the current landforms, with later fluvial and then aeolian activity. Terby crater thus preserves a geologic record spanning multiple periods of Mars' history.
The document discusses various geophysical investigation methods used in soil investigations, including seismic refraction and reflection surveys, resistivity surveys, and electromagnetic induction. It provides details on how each method works, including generating and measuring seismic waves or electrical currents and voltages in the ground to infer properties of subsurface soil and rock layers. Advantages are that the methods provide continuous subsurface profiles quickly and non-invasively over large areas. Examples of applications given include mapping bedrock, faults, and contaminant plumes.
The document discusses the tools used for subsurface analysis in geology, including well logs, cores, seismic data, and gravity and magnetic surveys. It focuses on well logs and seismic data. Well logs provide high vertical resolution and help delimit bounding surfaces and establish lithology. Seismic data provide high lateral continuity and resolution to define sediment geometries. Together these tools are used for allostratigraphy and sequence stratigraphy by identifying bounding discontinuities and sequences reflecting changes in relative sea level.
Okay, here are the steps to solve this problem:
(a) (i) Using the equation: Depth = 2.5 km + 0.3(Age)1/2
Set Depth = 4700 m
4700 = 2.5 + 0.3(Age)1/2
4700 - 2.5 = 0.3(Age)1/2
4697.5 = 0.3(Age)1/2
(4697.5/0.3)2 = Age
Age = 80 Myr
(ii) Spreading rate = Distance from ridge / Age
= 1600 km / 80 Myr
= 20 km/Myr
(b) This is a half
This document discusses various geophysical well logging methods used to delineate aquifers and estimate water quality, including resistivity, spontaneous potential, radioactivity, neutron, temperature, and fluid resistivity logging. Resistivity logging measures the resistivity of formations and can help determine lithology, porosity, and fluid salinity. Spontaneous potential logging indicates bed boundaries and distinguishes shale from permeable rocks. Radioactivity logging uses natural gamma rays or gamma-gamma techniques to identify lithology and determine porosity. Neutron logging measures hydrogen content to estimate porosity and moisture levels. Temperature and fluid resistivity logging provide additional information about groundwater. These geophysical logs provide critical subsurface data for groundwater exploration and management.
Borehole geophysics is the science of recording and analyzing measurements of physical properties made in wells or test holes. Probes that measure different properties are lowered into the borehole to collect continuous or point data that is graphically displayed as a geophysical log. Multiple logs typically are collected to take advantage of their synergistic nature--much more can be learned by the analysis of a suite of logs as a group than by the analysis of the same logs individually. Borehole geophysics is used in ground-water and environmental investigations to obtain information on well construction, rock lithology and fractures, permeability and porosity, and water quality. The geophysical logging system consists of probes, cable and drawworks, power and processing modules, and data recording units. State-of-the-art logging systems are controlled by a computer and can collect multiple logs with one pass of the probe
Hydrogeological studies were conducted that included infiltration tests, geophysical surveys, borehole drilling, and aquifer mapping. An infiltration test at the CLRI campus in Chennai found the soil type to be silty clay with infiltration rates between 3-30 cm/hr depending on time. Vertical electrical sounding using Schlumberger configuration identified aquifers down to 300m consisting of Quaternary alluvium and Cuddalore Sandstone. Borehole drilling using a DTH rig collected lithology and geophysical logs. Aquifer mapping was done using topographical sheets to delineate the extent, depth, and productivity of aquifers across the study area.
Chemostratigraphy is the study of chemical variations in sedimentary rocks to determine stratigraphic relationships. It uses inorganic geochemical data like carbon and oxygen isotopes to correlate rock layers. Oxygen isotopes fractionate with temperature changes and are measured in marine organism shells to create records for paleoclimate analysis. Carbon also has stable isotopes that provide information about past climate, evolution, and atmospheric CO2 levels. Chemostratigraphy has advantages over other correlation techniques as it can be used on any aged sediments regardless of lithology or environment. It has been applied successfully at major geologic boundaries and in unconventional reservoirs. Recent studies have also used sulfur and strontium isotopes to better understand changes around the Ordov
The document summarizes the analysis of layered deposits inside the 174 km diameter Terby impact crater located on Mars. Stratigraphic and mineralogical analysis using multiple datasets suggests the deposits were formed subaqueously during the Noachian period. The thickest sequences display fan delta morphologies indicative of prograding/onlapping sedimentation over time. Phyllosilicates detected within layers support a sedimentary environment with sustained liquid water. Erosion during the Hesperian sculpted the current landforms, with later fluvial and then aeolian activity. Terby crater thus preserves a geologic record spanning multiple periods of Mars' history.
The document discusses various geophysical investigation methods used in soil investigations, including seismic refraction and reflection surveys, resistivity surveys, and electromagnetic induction. It provides details on how each method works, including generating and measuring seismic waves or electrical currents and voltages in the ground to infer properties of subsurface soil and rock layers. Advantages are that the methods provide continuous subsurface profiles quickly and non-invasively over large areas. Examples of applications given include mapping bedrock, faults, and contaminant plumes.
The document discusses the tools used for subsurface analysis in geology, including well logs, cores, seismic data, and gravity and magnetic surveys. It focuses on well logs and seismic data. Well logs provide high vertical resolution and help delimit bounding surfaces and establish lithology. Seismic data provide high lateral continuity and resolution to define sediment geometries. Together these tools are used for allostratigraphy and sequence stratigraphy by identifying bounding discontinuities and sequences reflecting changes in relative sea level.
Okay, here are the steps to solve this problem:
(a) (i) Using the equation: Depth = 2.5 km + 0.3(Age)1/2
Set Depth = 4700 m
4700 = 2.5 + 0.3(Age)1/2
4700 - 2.5 = 0.3(Age)1/2
4697.5 = 0.3(Age)1/2
(4697.5/0.3)2 = Age
Age = 80 Myr
(ii) Spreading rate = Distance from ridge / Age
= 1600 km / 80 Myr
= 20 km/Myr
(b) This is a half
This document discusses various geophysical well logging methods used to delineate aquifers and estimate water quality, including resistivity, spontaneous potential, radioactivity, neutron, temperature, and fluid resistivity logging. Resistivity logging measures the resistivity of formations and can help determine lithology, porosity, and fluid salinity. Spontaneous potential logging indicates bed boundaries and distinguishes shale from permeable rocks. Radioactivity logging uses natural gamma rays or gamma-gamma techniques to identify lithology and determine porosity. Neutron logging measures hydrogen content to estimate porosity and moisture levels. Temperature and fluid resistivity logging provide additional information about groundwater. These geophysical logs provide critical subsurface data for groundwater exploration and management.
Borehole geophysics is the science of recording and analyzing measurements of physical properties made in wells or test holes. Probes that measure different properties are lowered into the borehole to collect continuous or point data that is graphically displayed as a geophysical log. Multiple logs typically are collected to take advantage of their synergistic nature--much more can be learned by the analysis of a suite of logs as a group than by the analysis of the same logs individually. Borehole geophysics is used in ground-water and environmental investigations to obtain information on well construction, rock lithology and fractures, permeability and porosity, and water quality. The geophysical logging system consists of probes, cable and drawworks, power and processing modules, and data recording units. State-of-the-art logging systems are controlled by a computer and can collect multiple logs with one pass of the probe
Hydrogeological studies were conducted that included infiltration tests, geophysical surveys, borehole drilling, and aquifer mapping. An infiltration test at the CLRI campus in Chennai found the soil type to be silty clay with infiltration rates between 3-30 cm/hr depending on time. Vertical electrical sounding using Schlumberger configuration identified aquifers down to 300m consisting of Quaternary alluvium and Cuddalore Sandstone. Borehole drilling using a DTH rig collected lithology and geophysical logs. Aquifer mapping was done using topographical sheets to delineate the extent, depth, and productivity of aquifers across the study area.
Chemostratigraphy is the study of chemical variations in sedimentary rocks to determine stratigraphic relationships. It uses inorganic geochemical data like carbon and oxygen isotopes to correlate rock layers. Oxygen isotopes fractionate with temperature changes and are measured in marine organism shells to create records for paleoclimate analysis. Carbon also has stable isotopes that provide information about past climate, evolution, and atmospheric CO2 levels. Chemostratigraphy has advantages over other correlation techniques as it can be used on any aged sediments regardless of lithology or environment. It has been applied successfully at major geologic boundaries and in unconventional reservoirs. Recent studies have also used sulfur and strontium isotopes to better understand changes around the Ordov
Detection of Low-Speed Layer (Lvl) In Seismic Refraction Survey Using Combine...iosrjce
A combination of two geophysical methods not only helps to enhance the accuracy of results but also
helps to detect the presence of a low velocity layer which cannot be detected by refraction shooting alone. The
Direct Current resistivity method was combined with the seismic refraction method to infer the lithology of
Nnodo (Latitude 6.300
- 6.320N and Longitude 8.100
- 8.120E), Nigeria, during which a low-velocity layer was
encountered. The major instruments used were the signal enhancement seismograph and the ABEM terrameter.
The seismic refraction method revealed three layers of the earth from its surface with velocities 300m/s,
1200m/s and 2100m/s which were interpreted as dry/loose sand, saturated sand and limestone respectively. The
resistivity method however, revealed five geoelectric layers with resistivity values 957 Ωm,363 Ωm,1033
Ωm,489 Ωm and 135 Ωm which were interpreted as dry soil, saturated sand, sandy clay, limestone and shale
respectively. A comparison of the two results showed that the third layer from the surface at Nnodo interpreted
as probably sandy clay( from the resistivity survey) was not detected in the seismic refraction survey. This was
suspected to be a low-velocity layer with a velocity of about 600m/s. Hence the layer of limestone according to
the seismic result is the fourth layer of the study area and not the third.The actual lithology of the third layer
which the seismic refraction method could not detect is sandy clay. This was evident from the resistivity result.
The lithologic sequence of the study area from the earth’s surface is therefore dry soil, saturated sand, sandy
clay, limestone and fractured shale(wet).
This document provides an outline for a course on sequence stratigraphy. It covers key concepts in stratigraphy including sedimentary depositional environments, facies analysis, sequence stratigraphy principles, and causes of sea level change. Common siliciclastic and carbonate stratigraphic successions are examined. The role of base level and relative sea level changes in controlling sediment accumulation and sequence boundaries is discussed.
well logging project report_ongc project studentknigh7
This dissertation report discusses characterizing oil and gas reservoirs using open hole wireline logging tools and techniques. It provides background on reservoir properties that can be measured using logs like resistivity, porosity, and saturation. It also describes the various electrical, radioactive, sonic, and other open hole wireline logging tools and their measurement principles.
This document discusses seismic stratigraphy, which uses seismic data to extract stratigraphic information about subsurface rock layers. It defines seismic waves and methods, including refraction and reflection. Reflection seismic is more commonly used to identify structures like folds and faults beneath the surface. Key parameters for interpretation are reflection configuration, continuity, amplitude, frequency, and interval velocity. Depositional environments are also identified based on their relationship to the wave base.
Interpretation and recognition of depositional systems using seismic dataDiego Timoteo
This document discusses the interpretation and recognition of depositional systems using seismic data. It covers five key stages: (1) reviewing basic concepts of sequence stratigraphy, (2) understanding the physical foundations of rocks and seismic reflection methods, (3) seismic stratigraphic interpretation of depositional sequences and system tracts, (4) recognizing depositional systems through seismic facies analysis, and (5) advanced seismic interpretation applications. Accurate interpretation requires integrating data from outcrops, cores, well logs, and seismic sections to constrain models, especially in frontier regions with limited data. The techniques allow correlating and mapping stratigraphic units to aid paleogeographic reconstruction and facies/lithology prediction away from control points.
The continental crust covers nearly a third of the Earth’s surface, extends vertically from the Earth’s surface to the Moho discontinuity.
It is less dense than oceanic crust.
Compositionally is dominating by silicate elements
Models for the differentiation of the continental crust shows when and how it was formed
Reconciling the sedimentary and igneous records indicates that it may take up to one billion years for a new crust to dominate the sedimentary record.
The continental crust of the Earth differs from the crust of other planets in the Solar System
Its formation modified the composition of the mantle and the atmosphere
It supports life
And it remains a sink for CO2
Evaluating the composition of new continental crust can provide important clues as to how and when it may have been generated. Which is required understanding the differentiation processes of igneous (granites) and sedimentary rocks
The study of sequence stratigraphy and sedimentary system in Muglad Basiniosrjce
Application of sequence stratigraphy theory, by levels of base level cycle sequence feature analysis,
combined with core and log data, establish the sequence stratigraphic framework. The Cretaceous sedimentary
strata are divided into six two sequences and 14 third-order sequences. In sequence stratigraphy based,
combine well logging, seismic and core observation, and comprehensive analysis of each well rock type, color,
bedding and other construction phase marks. Identify the Cretaceous strata have delta, meandering fluvial
facies and braided river with three main facies. Detailed study of Cretaceous sedimentary characteristics,
identify each sedimentary microfacies, sedimentary facies sequence established in the region
The document discusses techniques for seismic stratigraphy analysis and interpretation. It describes delineating depositional sequences using reflection termination mapping. Reflection terminations indicate strata discontinuities and can be truncation, toplap, baselap, onlap, or downlap. Seismic sequence analysis involves analyzing seismic sequences, facies, and interpreting depositional environments. Reflection configurations, continuity, amplitude, and frequency are used to define seismic facies units representing depositional environments and lithofacies.
This document discusses sedimentary basins, including their definition, formation, and analysis. Key points:
- Sedimentary basins form in low areas of the crust where sediments accumulate due to tectonic activity that creates relief. They range in size from hundreds of meters to ocean basins.
- Tectonics is the primary control on sedimentation, affecting factors like sediment supply and depositional environment. Sedimentation also influences tectonics by increasing lithospheric loading.
- Basins can be formed by processes including faulting, thermal subsidence of extended lithosphere, and flexural subsidence caused by loading of the lithosphere.
- Analyzing features of sedimentary
Geochemical cycle and mobility of elementsPramoda Raj
The document discusses geochemical concepts relevant to mineral exploration, including the geochemical environment, cycle, dispersion, and mobility of elements. It describes the deep-seated and surfacial environments and how materials move between them in the geochemical cycle. Mobility depends on factors like viscosity and particle size. Hypogene mobility occurs under high pressure-temperature conditions, while supergene mobility is influenced by siliceous or sulfide environments at the surface. Indicator and pathfinder elements are discussed for detecting targeted ore deposits.
Surface and subsurface investigations for groundwaterPrabinBimali
This document describes various geological and geophysical methods used for groundwater exploration, including remote sensing, surface geophysical methods, and sub-surface geophysical well logging techniques. It discusses geomorphological mapping of surface features indicative of groundwater such as stream junctions. Electromagnetic, electrical resistivity, seismic, and gravity methods are described. The principles, equipment, and applications of each method are explained in detail. Well logging techniques including electric, radioactive, induction, sonic, and fluid logs are also summarized.
This document examines four Venusian shield fields through geological mapping using Synthetic Aperture Radar imagery. It finds that each field displays a distinct morphology, possibly related to differences in magma properties or eruption styles. Mapping allowed trends in shield morphologies to be recorded across different areas of Venus' surface. However, due to the resolution of imagery, establishing detailed stratigraphy within individual fields is challenging.
Geophysical well logging uses sensors located in boreholes to measure physical properties of surrounding rocks as a function of depth. Well logs are used to identify geological formations and fluids, correlate between holes, and evaluate reservoir formations. Common logging methods include electrical resistivity, self-potential, nuclear, acoustic, and thermal measurements. The objective is to determine in situ rock and fluid properties, though drilling disturbs the formation. Effective depth of penetration varies between tools and formations. Well logging aims to identify potential reservoirs by determining porosity, permeability, and fluid contents.
Seismic Reflection Surveys in Search for Iron Oxide Copper-Gold (IOCG) Depositsiosrjce
Seismic reflection method can delineate very complex geological structures hence it might be very
effective for detecting the presence of Iron Oxide Copper-Gold (IOCG) deposits. Despite this superior
attributes, there exist a real problem for exploration beyond the immediate vicinity of a known deposit. All
previous studies have focused upon high resolution detection of mineralization and the hosting structures at
mine scale. No argument for “regional” exploration have been proposed probably because a cost benefit
analysis has never be conducted at such scale to proceed with such exploration venture. In this study, we
analyze the feasibility of such regional exploration by modelling a Vulcan IOCGU deposit scenario were a 2D
seismic survey with relatively sparse source-receiver geometry was used to detect the presence of a possible
intrusive package within 2km depth range. The modelling results demonstrates that seismic reflection method
using 10m geophones and 20m shot spacing can be used to image deposit within the depth of 2km. The
presence of reflections was visibly observed especially at the edges of intrusive packages hence it is suggested
that application of seismic reflection methods perhaps will remains the best alternative and most viable method
for exploring deep seated IOCG
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.
This document discusses well log formation evaluations. It outlines the key information that can be obtained from well logs, including rock type, properties, fluids, and engineering details. It then describes the various types of well logs that can be run, including lithologic logs (SP, gamma ray), porosity logs (neutron, density, sonic), resistivity logs, and others. The document explains how each log works and the parameters it measures. It also discusses log applications for correlation, modeling, and more. Finally, it covers the logging operation and considerations for running logs in vertical and horizontal wells.
Sedimentology application in petroleum industryAndi Anriansyah
This document provides an overview of sedimentology and its applications in the petroleum industry. It discusses key concepts in sedimentology including sedimentary rocks, depositional environments, sediment transport processes, and sedimentary structures. These concepts are important for understanding reservoir heterogeneity, predicting texture, and informing exploration and production strategies. The document cautions against oversimplifying depositional environments and stresses the importance of analyzing sediment transport and depositional processes to avoid misinterpretation.
The Mini-RF radar on the Lunar Reconnaissance Orbiter has revealed new details about impact melt deposits and ejecta flows on the lunar surface. Long melt flows from the craters Tycho and Glushko show variations in radar backscatter and polarization that resemble features of terrestrial lava flows. Small craters also exhibit a variety of melt deposits including ponds and flows. Some features appear to be ejecta flows from debris rather than melted rock. Impact melt flows have very high polarization ratios, suggesting rough surfaces at the centimeter to decimeter scale. In some cases, melt ponds and flows are seen without an identifiable source crater. These observations provide insights into similar features on Venus and the emplacement of melted rock
Este documento describe la curva de potencial espontáneo (SP), la cual mide el potencial eléctrico entre un electrodo en la superficie y otro dentro de un pozo. La curva SP es útil para la correlación entre pozos, identificación litológica, y estimación de porosidad y permeabilidad. Se explican los factores que afectan la curva SP, como la distribución de corriente, espesor de capas, y presencia de arcillas. La curva SP ha sido una herramienta importante en la industria petrolera para difer
Lightning Talk #9: How UX and Data Storytelling Can Shape Policy by Mika Aldabaux singapore
How can we take UX and Data Storytelling out of the tech context and use them to change the way government behaves?
Showcasing the truth is the highest goal of data storytelling. Because the design of a chart can affect the interpretation of data in a major way, one must wield visual tools with care and deliberation. Using quantitative facts to evoke an emotional response is best achieved with the combination of UX and data storytelling.
Detection of Low-Speed Layer (Lvl) In Seismic Refraction Survey Using Combine...iosrjce
A combination of two geophysical methods not only helps to enhance the accuracy of results but also
helps to detect the presence of a low velocity layer which cannot be detected by refraction shooting alone. The
Direct Current resistivity method was combined with the seismic refraction method to infer the lithology of
Nnodo (Latitude 6.300
- 6.320N and Longitude 8.100
- 8.120E), Nigeria, during which a low-velocity layer was
encountered. The major instruments used were the signal enhancement seismograph and the ABEM terrameter.
The seismic refraction method revealed three layers of the earth from its surface with velocities 300m/s,
1200m/s and 2100m/s which were interpreted as dry/loose sand, saturated sand and limestone respectively. The
resistivity method however, revealed five geoelectric layers with resistivity values 957 Ωm,363 Ωm,1033
Ωm,489 Ωm and 135 Ωm which were interpreted as dry soil, saturated sand, sandy clay, limestone and shale
respectively. A comparison of the two results showed that the third layer from the surface at Nnodo interpreted
as probably sandy clay( from the resistivity survey) was not detected in the seismic refraction survey. This was
suspected to be a low-velocity layer with a velocity of about 600m/s. Hence the layer of limestone according to
the seismic result is the fourth layer of the study area and not the third.The actual lithology of the third layer
which the seismic refraction method could not detect is sandy clay. This was evident from the resistivity result.
The lithologic sequence of the study area from the earth’s surface is therefore dry soil, saturated sand, sandy
clay, limestone and fractured shale(wet).
This document provides an outline for a course on sequence stratigraphy. It covers key concepts in stratigraphy including sedimentary depositional environments, facies analysis, sequence stratigraphy principles, and causes of sea level change. Common siliciclastic and carbonate stratigraphic successions are examined. The role of base level and relative sea level changes in controlling sediment accumulation and sequence boundaries is discussed.
well logging project report_ongc project studentknigh7
This dissertation report discusses characterizing oil and gas reservoirs using open hole wireline logging tools and techniques. It provides background on reservoir properties that can be measured using logs like resistivity, porosity, and saturation. It also describes the various electrical, radioactive, sonic, and other open hole wireline logging tools and their measurement principles.
This document discusses seismic stratigraphy, which uses seismic data to extract stratigraphic information about subsurface rock layers. It defines seismic waves and methods, including refraction and reflection. Reflection seismic is more commonly used to identify structures like folds and faults beneath the surface. Key parameters for interpretation are reflection configuration, continuity, amplitude, frequency, and interval velocity. Depositional environments are also identified based on their relationship to the wave base.
Interpretation and recognition of depositional systems using seismic dataDiego Timoteo
This document discusses the interpretation and recognition of depositional systems using seismic data. It covers five key stages: (1) reviewing basic concepts of sequence stratigraphy, (2) understanding the physical foundations of rocks and seismic reflection methods, (3) seismic stratigraphic interpretation of depositional sequences and system tracts, (4) recognizing depositional systems through seismic facies analysis, and (5) advanced seismic interpretation applications. Accurate interpretation requires integrating data from outcrops, cores, well logs, and seismic sections to constrain models, especially in frontier regions with limited data. The techniques allow correlating and mapping stratigraphic units to aid paleogeographic reconstruction and facies/lithology prediction away from control points.
The continental crust covers nearly a third of the Earth’s surface, extends vertically from the Earth’s surface to the Moho discontinuity.
It is less dense than oceanic crust.
Compositionally is dominating by silicate elements
Models for the differentiation of the continental crust shows when and how it was formed
Reconciling the sedimentary and igneous records indicates that it may take up to one billion years for a new crust to dominate the sedimentary record.
The continental crust of the Earth differs from the crust of other planets in the Solar System
Its formation modified the composition of the mantle and the atmosphere
It supports life
And it remains a sink for CO2
Evaluating the composition of new continental crust can provide important clues as to how and when it may have been generated. Which is required understanding the differentiation processes of igneous (granites) and sedimentary rocks
The study of sequence stratigraphy and sedimentary system in Muglad Basiniosrjce
Application of sequence stratigraphy theory, by levels of base level cycle sequence feature analysis,
combined with core and log data, establish the sequence stratigraphic framework. The Cretaceous sedimentary
strata are divided into six two sequences and 14 third-order sequences. In sequence stratigraphy based,
combine well logging, seismic and core observation, and comprehensive analysis of each well rock type, color,
bedding and other construction phase marks. Identify the Cretaceous strata have delta, meandering fluvial
facies and braided river with three main facies. Detailed study of Cretaceous sedimentary characteristics,
identify each sedimentary microfacies, sedimentary facies sequence established in the region
The document discusses techniques for seismic stratigraphy analysis and interpretation. It describes delineating depositional sequences using reflection termination mapping. Reflection terminations indicate strata discontinuities and can be truncation, toplap, baselap, onlap, or downlap. Seismic sequence analysis involves analyzing seismic sequences, facies, and interpreting depositional environments. Reflection configurations, continuity, amplitude, and frequency are used to define seismic facies units representing depositional environments and lithofacies.
This document discusses sedimentary basins, including their definition, formation, and analysis. Key points:
- Sedimentary basins form in low areas of the crust where sediments accumulate due to tectonic activity that creates relief. They range in size from hundreds of meters to ocean basins.
- Tectonics is the primary control on sedimentation, affecting factors like sediment supply and depositional environment. Sedimentation also influences tectonics by increasing lithospheric loading.
- Basins can be formed by processes including faulting, thermal subsidence of extended lithosphere, and flexural subsidence caused by loading of the lithosphere.
- Analyzing features of sedimentary
Geochemical cycle and mobility of elementsPramoda Raj
The document discusses geochemical concepts relevant to mineral exploration, including the geochemical environment, cycle, dispersion, and mobility of elements. It describes the deep-seated and surfacial environments and how materials move between them in the geochemical cycle. Mobility depends on factors like viscosity and particle size. Hypogene mobility occurs under high pressure-temperature conditions, while supergene mobility is influenced by siliceous or sulfide environments at the surface. Indicator and pathfinder elements are discussed for detecting targeted ore deposits.
Surface and subsurface investigations for groundwaterPrabinBimali
This document describes various geological and geophysical methods used for groundwater exploration, including remote sensing, surface geophysical methods, and sub-surface geophysical well logging techniques. It discusses geomorphological mapping of surface features indicative of groundwater such as stream junctions. Electromagnetic, electrical resistivity, seismic, and gravity methods are described. The principles, equipment, and applications of each method are explained in detail. Well logging techniques including electric, radioactive, induction, sonic, and fluid logs are also summarized.
This document examines four Venusian shield fields through geological mapping using Synthetic Aperture Radar imagery. It finds that each field displays a distinct morphology, possibly related to differences in magma properties or eruption styles. Mapping allowed trends in shield morphologies to be recorded across different areas of Venus' surface. However, due to the resolution of imagery, establishing detailed stratigraphy within individual fields is challenging.
Geophysical well logging uses sensors located in boreholes to measure physical properties of surrounding rocks as a function of depth. Well logs are used to identify geological formations and fluids, correlate between holes, and evaluate reservoir formations. Common logging methods include electrical resistivity, self-potential, nuclear, acoustic, and thermal measurements. The objective is to determine in situ rock and fluid properties, though drilling disturbs the formation. Effective depth of penetration varies between tools and formations. Well logging aims to identify potential reservoirs by determining porosity, permeability, and fluid contents.
Seismic Reflection Surveys in Search for Iron Oxide Copper-Gold (IOCG) Depositsiosrjce
Seismic reflection method can delineate very complex geological structures hence it might be very
effective for detecting the presence of Iron Oxide Copper-Gold (IOCG) deposits. Despite this superior
attributes, there exist a real problem for exploration beyond the immediate vicinity of a known deposit. All
previous studies have focused upon high resolution detection of mineralization and the hosting structures at
mine scale. No argument for “regional” exploration have been proposed probably because a cost benefit
analysis has never be conducted at such scale to proceed with such exploration venture. In this study, we
analyze the feasibility of such regional exploration by modelling a Vulcan IOCGU deposit scenario were a 2D
seismic survey with relatively sparse source-receiver geometry was used to detect the presence of a possible
intrusive package within 2km depth range. The modelling results demonstrates that seismic reflection method
using 10m geophones and 20m shot spacing can be used to image deposit within the depth of 2km. The
presence of reflections was visibly observed especially at the edges of intrusive packages hence it is suggested
that application of seismic reflection methods perhaps will remains the best alternative and most viable method
for exploring deep seated IOCG
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.
This document discusses well log formation evaluations. It outlines the key information that can be obtained from well logs, including rock type, properties, fluids, and engineering details. It then describes the various types of well logs that can be run, including lithologic logs (SP, gamma ray), porosity logs (neutron, density, sonic), resistivity logs, and others. The document explains how each log works and the parameters it measures. It also discusses log applications for correlation, modeling, and more. Finally, it covers the logging operation and considerations for running logs in vertical and horizontal wells.
Sedimentology application in petroleum industryAndi Anriansyah
This document provides an overview of sedimentology and its applications in the petroleum industry. It discusses key concepts in sedimentology including sedimentary rocks, depositional environments, sediment transport processes, and sedimentary structures. These concepts are important for understanding reservoir heterogeneity, predicting texture, and informing exploration and production strategies. The document cautions against oversimplifying depositional environments and stresses the importance of analyzing sediment transport and depositional processes to avoid misinterpretation.
The Mini-RF radar on the Lunar Reconnaissance Orbiter has revealed new details about impact melt deposits and ejecta flows on the lunar surface. Long melt flows from the craters Tycho and Glushko show variations in radar backscatter and polarization that resemble features of terrestrial lava flows. Small craters also exhibit a variety of melt deposits including ponds and flows. Some features appear to be ejecta flows from debris rather than melted rock. Impact melt flows have very high polarization ratios, suggesting rough surfaces at the centimeter to decimeter scale. In some cases, melt ponds and flows are seen without an identifiable source crater. These observations provide insights into similar features on Venus and the emplacement of melted rock
Este documento describe la curva de potencial espontáneo (SP), la cual mide el potencial eléctrico entre un electrodo en la superficie y otro dentro de un pozo. La curva SP es útil para la correlación entre pozos, identificación litológica, y estimación de porosidad y permeabilidad. Se explican los factores que afectan la curva SP, como la distribución de corriente, espesor de capas, y presencia de arcillas. La curva SP ha sido una herramienta importante en la industria petrolera para difer
Lightning Talk #9: How UX and Data Storytelling Can Shape Policy by Mika Aldabaux singapore
How can we take UX and Data Storytelling out of the tech context and use them to change the way government behaves?
Showcasing the truth is the highest goal of data storytelling. Because the design of a chart can affect the interpretation of data in a major way, one must wield visual tools with care and deliberation. Using quantitative facts to evoke an emotional response is best achieved with the combination of UX and data storytelling.
The document discusses how personalization and dynamic content are becoming increasingly important on websites. It notes that 52% of marketers see content personalization as critical and 75% of consumers like it when brands personalize their content. However, personalization can create issues for search engine optimization as dynamic URLs and content are more difficult for search engines to index than static pages. The document provides tips for SEOs to help address these personalization and SEO challenges, such as using static URLs when possible and submitting accurate sitemaps.
This document summarizes a study of CEO succession events among the largest 100 U.S. corporations between 2005-2015. The study analyzed executives who were passed over for the CEO role ("succession losers") and their subsequent careers. It found that 74% of passed over executives left their companies, with 30% eventually becoming CEOs elsewhere. However, companies led by succession losers saw average stock price declines of 13% over 3 years, compared to gains for companies whose CEO selections remained unchanged. The findings suggest that boards generally identify the most qualified CEO candidates, though differences between internal and external hires complicate comparisons.
How to Build a Dynamic Social Media PlanPost Planner
Stop guessing and wasting your time on networks and strategies that don’t work!
Join Rebekah Radice and Katie Lance to learn how to optimize your social networks, the best kept secrets for hot content, top time management tools, and much more!
Watch the replay here: bit.ly/socialmedia-plan
Artificial intelligence (AI) is everywhere, promising self-driving cars, medical breakthroughs, and new ways of working. But how do you separate hype from reality? How can your company apply AI to solve real business problems?
Here’s what AI learnings your business should keep in mind for 2017.
Study: The Future of VR, AR and Self-Driving CarsLinkedIn
We asked LinkedIn members worldwide about their levels of interest in the latest wave of technology: whether they’re using wearables, and whether they intend to buy self-driving cars and VR headsets as they become available. We asked them too about their attitudes to technology and to the growing role of Artificial Intelligence (AI) in the devices that they use. The answers were fascinating – and in many cases, surprising.
This SlideShare explores the full results of this study, including detailed market-by-market breakdowns of intention levels for each technology – and how attitudes change with age, location and seniority level. If you’re marketing a tech brand – or planning to use VR and wearables to reach a professional audience – then these are insights you won’t want to miss.
Well logs can be states as “a recording against depth of any of the characteristics of the rock formations traversed by a measuring apparatus in the well-bore.”
WELL LOG : Types of Logs, The Bore Hole Image, Interpreting Geophysical Well Logs, applications, Production logs, Well Log Classification and Cataloging
Exploration and Exploitation Groundwater From Journal and MaterialsMartheana Kencanawati
This document discusses various methods for exploring and exploiting groundwater resources, including surface exploration techniques like remote sensing, geophysical methods, and geological mapping, as well as subsurface techniques like test drilling and geophysical well logging. It provides details on specific surface geophysical methods like electrical resistivity, seismic refraction and reflection, and gravitational surveys. Subsurface techniques covered include well construction, borehole geophysical logging tools for measuring resistivity, spontaneous potential, natural gamma radiation, neutron porosity, temperature, and borehole diameter. The document emphasizes integrating multiple exploration techniques to better understand subsurface geology and locate groundwater.
Reflecting method of seismic prospectingPramoda Raj
This document provides an overview of seismic prospecting methods. It discusses the different types of seismic waves, including P-waves, S-waves, and surface waves. The seismic reflecting method is described as using controlled seismic sources to generate waves that reflect off underground formations and are detected by sensors at the surface. Reflection seismology can be used to map subsurface geology at various depths for applications like hydrocarbon exploration, engineering surveys, and studying crustal structures. In summary, the document outlines seismic prospecting techniques, focusing on the seismic reflecting method of using controlled sources and detecting reflected waves.
This document provides an overview of seismic prospecting methods. It discusses the different types of seismic waves, including P-waves, S-waves, and surface waves. The seismic reflecting method is described as using controlled seismic sources to generate waves that reflect off underground formations and are detected by sensors at the surface. Reflection seismology can be used to map subsurface geology at various depths for applications in engineering, minerals and hydrocarbon exploration, and studying crustal structures.
Role of Seismic Attributes in Petroleum Exploration_30May22.pptxNagaLakshmiVasa
The document discusses seismic attributes which are measurable properties of seismic data computed through mathematical manipulation to highlight geological features. It describes how seismic waves are reflected and refracted and how this seismic response is recorded. The key types of seismic attributes discussed are amplitude, phase, frequency and complex trace attributes. Specific amplitude attributes like RMS amplitude and sweetness are explained. The document also covers applications of seismic attributes like direct hydrocarbon indication and limitations. Spectral decomposition and AVO/AVA analysis are also summarized.
GEOLOGICAL INVESTIGATTION OF PERCOLATION TANKIRJET Journal
1) A geological investigation of a percolation tank site in Karad, India was conducted which included surface surveys and subsurface investigation using resistivity methods.
2) The resistivity investigation found loose soil, sand, weathered basalt, and fractured rock between 0-25 meters depth, indicating potential for groundwater recharge from the percolation tank.
3) Below 10 meters depth, jointed hard rock and compact basalt were found, suggesting the initial purpose of the tank as a percolation tank was only partially fulfilled, as water may flow down through shallow layers instead of fully percolating. Excavating the reservoir deeper could improve percolation.
Subsurface Determination Of Cavities In Limestone Rock Area By Geoelectric Me...IJERA Editor
Two Dimensional of geoelectric method can be used to find out the conductive formation in the earth surface. The purpose of this research is to give the description about the geological subsurface formation, that the high resistivity value is indicate the potential area of cave and void in the limestone rocks. The dipole dipolegeoelectric method is used in this research with the path of lines is 250 m with 10 m electrode spacing. The total lines is 7 and the azimuth is from east to west. Resistivity method is started with inject the electrical current into the earth by current electrode, then potential difference will arise and measured by potential electrode. Variation value of resistance for each layer rock can calculated by divided potential defference with current value. The existence of the cavity is known by the resistivity value is more than 2500 ohm-m, while the cracks have a resistivity of 1500 to 2500 ohm-m.
Prospecting by radioactivity logging methodsPramoda Raj
This document discusses various well logging methods used in geophysical exploration, specifically focusing on radioactivity logging. It describes four main types of radioactivity logs: gamma ray logs, neutron-gamma ray logs, pulsed neutron logs, and formation density logs. Gamma ray logs measure natural radioactivity to characterize rock formations. Neutron-gamma ray logs measure induced radioactivity to evaluate porosity. Pulsed neutron logs can distinguish between oil, water, and gas, and are not influenced by borehole conditions. Formation density logs measure gamma ray energy loss to determine formation density and porosity. The document provides details on the principles and applications of each method.
The document provides an overview of well logging techniques and tools. It discusses the history of well logging beginning in 1912 and describes some common downhole tools used for well logging including gamma ray, spontaneous potential, neutron, density, resistivity, and acoustic logs. It explains what each tool measures and how the data can be used to evaluate properties of the formation like lithology, porosity, fluid content, and structure for purposes like hydrocarbon exploration and reservoir characterization.
Well logging involves lowering instruments into boreholes to record properties of rock formations. It provides critical information for oil and gas, groundwater, and mineral exploration. Key logs measure natural gamma radiation, electrical resistivity, acoustic properties, and nuclear properties like neutron count. Together these logs characterize porosity, lithology, fluid content and other formation features. Well logging has evolved significantly since the first electric log in 1927, with new tools, digital acquisition, and measurement-while-drilling capabilities. It remains a core technology for understanding subsurface geology.
The document discusses the classification of well logs. It explains that logs can be classified based on their technology (open hole vs cased hole logs) or their function (lithology, electrical, porosity, nuclear logs). Open hole logs are run before casing while cased hole logs are done after casing through the metal piping. Various logging tools are described, including gamma ray, resistivity, density, neutron, and sonic logs which provide data on formation properties like lithology, porosity, and fluid content. Nuclear logs using gamma rays and neutrons can evaluate formations through casing as well.
Spectral gamma logs record radiation from potassium, thorium, and uranium, which can be used to evaluate clay content and type as well as source rock potential. Diffused gamma-ray logs use a gamma source and two detectors to measure photoelectric absorption and Compton scattering, related to lithology and bulk density. Open-hole logging performs measurements in uncased wells while cased-hole logging obtains data through the well casing.
This document discusses various geophysical methods used to study the subsurface of the earth, including gravity, magnetic, electrical, seismic, radiometric, and geothermal methods. It explains the basic principles of each method, what physical properties are measured, how variations in those properties can provide information about subsurface features like rock types and structures. Applications are mentioned like mineral and groundwater exploration. Both advantages and limitations of each geophysical method are summarized.
Geophysical methods use principles of physics to study the subsurface structure of the earth. Electrical resistivity, magnetic, gravity, and seismic methods are some key geophysical techniques. They can be used to determine subsurface rock types, locate groundwater, ore deposits, and help ensure safe and economical construction. Geophysical investigations provide subsurface data quickly and non-invasively compared to drilling. They are useful for engineering projects and exploring for resources like minerals, oil, and gas.
Well logs are obtained by lowering measuring tools into wells to record properties of rock formations. They provide a signature of physical characteristics like porosity, lithology, and fluid saturation. Common logs measure resistivity, spontaneous potential, gamma radiation, neutrons, sonic velocity, and nuclear magnetic resonance to interpret rock and fluid properties. Logs can be open or cased hole and employ natural or induced phenomena to characterize formations.
This document describes various well logging techniques:
a) Gamma ray logs measure natural radioactivity to distinguish between shale and sandstone/limestone.
b) Spontaneous potential logs measure electrical potential between drilling mud and formation water to indicate permeability.
c) Resistivity logs measure formation resistance to electric current, with porous formations filled with saltwater having low resistivity and formations containing oil/gas having higher resistivity.
This document discusses key concepts in seismic stratigraphy used for interpreting subsurface geological features. It explains that seismic stratigraphy analyzes stratigraphic changes based on interpreting changes in seismic reflection waveforms rather than just travel times. Common stratigraphic features observable on seismic sections are described, such as sand lenses, reef bodies, salt domes, unconformities, and facies changes. Hydrocarbon indicators related to waveform parameters like amplitude, frequency, phase, and velocity are also outlined for detecting oil and gas reservoirs.
Similar to Geol342 sedimentation and stratigraphy (20)
1. 1/6/13 GEOL342 - Sedimentation and Stratigraphy
42: Sedimentation and Stratigraphy
2011
Geophysical stratigraphy:
Due to the lack of surface outcrop in many areas geophysical methods of correlation have been developed that
exploit the methods of physics to mapg the physical properties of rocks, including:
Density
Permeability
Porosity
Character of pore fluids
Variations in those properties with depth reveal the presence of different rock types and are used to create
vertical and lateral sections of rocks that can't directly be examined. There are two general approaches:
Well logs: that record information provided by probes that are placed down boreholes
Seismic studies: in which physical features of subsurface rocks are approximated based on seismic
wave propagation
Well logging
Direct sampling: Not all well information is remote. Bentonite muds are continually circulated through the drill
pipe as a coolant and lubricant for the drill bit. Rock chips are brought to surface with the mud, captured,
identified and logged, creating a direct lithologic record.
Aditional information comes from devices lowered into the borehole:
Caliper: measures the width of the drill hole. This indicates the presence of mudrocks, which are prone
to caving and sagging, hence constricting the borehole slightly.
Sonde: A probe lowered into hole to measure various electrical and physical properties of the rocks.
Gas detectors and gas chromatographs: measure gases in the well.
Gamma-ray log: measures natural radioactivity of the strata
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3. What the sonde records:
Spontaneous potential (SP) log: measures
difference in electrical potential between an
electrode on the sonde and one at the surface.
An electrical potential exists between the
natural pore fluids of the rock and the drilling
mud that invades those pores. Therefore, SP
logs are a measure of permeability:
Shales and limestone nearly
impermeable and have a 0 reading
Negative deflection for sandstones (high
permeability) or fluids with higher
conductivity than the drilling mud (like
saltwater)
Positive deflection for fluids with lower
conductivity than mud (like freshwater)
Resistivity (R) log: measures resistivity of
fluids in the surrounding rock to an applied
electrical current. Resistivity indicates amount
of fluid in the pore spaces, therefore R logs are
measures of porosity. Resistivity increases
with decreasing pore space.
High resistivity: dense rocks with no pores (quartzite, limestone.), rocks with non-conducting fluid in
their pores (like petroleum)
Low resistivity: rocks with significant porosity (sandstone), rocks with conducting fluid in their pores
(like salt water), rocks containing significant amounts of water in their crystal structure (clay-rich rocks).
Examples of Spontaneous Potential logs:
Fluvial deposit with point bar sequence and overbank mud shows fining-upward sequence.
4. 1/6/13 GEOL342 - Sedimentation and Stratigraphy
Deltaic deposit grading into shoreline Coarsening upward
sequence with thick sands.
Deltaic deposit grading into distributary channel and
interdistributary bay Coarsening upward sequence.
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5. 1/6/13 GEOL342 - Sedimentation and Stratigraphy
Deltaic deposit grading into delta plain Coarsening
upward sequence with thick sands.
Regressive shoreline Coarsening upward
sequence.
Dipmeter: measures resistivity in four directions. By this means, it locates contacts and identifies their dip
direction, allowing identification of folds, faults, and other structure.
Gamma-ray log: measures natural radioactivity of the rock. Most gamma radiation comes from decay of
40K. Therefore, the gamma-ray log is sensitive to rocks high in K-bearing minerals (feldspars, micas,
clays) including:
shales
feldspathic and lithic sandstones
In contrast, limestones and quartz rich sandstones produce low gamma ray values.
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Well-logging techniques all have one significant drawback: They require you to drill a borehole. There is a less
expensive alternative:
Seismic stratigraphy
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7. 1/6/13 GEOL342 - Sedimentation and Stratigraphy
Shots, pulses of sound are generated:
by explosives or a mechanical thumper
on Vibraseis trucks on land
by a shipboard air gun at sea.
Those waves that are propagated nearly straight
downward can be reflected off subsurface
interfaces of materials of different densities, such
as contacts between rock units.
Travel time is recorded by an array of
geophones on land or hydrophones at sea.
Reflections from each shot are recorded
as individual seismic profiles by the
geophones.
Information from each geophone in the
array is correlated, processed to remove
noise, and summed up across the array,
yielding a vertical line in which reflectors
as shown as wave-shaped deviations. This
is a one-dimensional plot of reflectors
beneath the shot
The array and thumper are then moved
slightly along a transect and a new seismic
shot made, which yields a separate trace.
Ultimately individual traces are displayed
together as seismic profiles,
approximating two dimensional images of
reflectors below the transect, each vertical line of which represents one shot.
More ambitious seismic techniques involve the deployment of two-dimensional geophone arrays to develop
three-dimensional seismic profiles.
Definitions:
Reflector: boundary that creates a seismic reflection
Reflection: acoustic waves created by sounds bouncing off of a reflector
Impedance: physical rock property of sound propagating through rock. A function of average sound
velocity and rock density
Impedance contrast: physical boundary within rocks producing a reflection
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Seismic stratigraphy can be
used for both deep and
shallow structural analysis.
Layered reflectors appear as
distinct horizons, whereas
structureless units or those of
uniform density show
random reflections. (E.G.:
the contrast between marine
sediments and a rising salt
structure - right.) But what,
exactly are these reflectors?
Simply, they are density
contrasts. These may be
caused by:
contacts between rock units
interface of different pore fluids (E.G.: petroleum and water)
unconformities
diagenetic features
The traces of seismic reflections have numerous aspects that can be measured:
amplitude
duration (2-way travel time)
area, etc.
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9. 1/6/13 GEOL342 - Sedimentation and Stratigraphy
This is pleasingly quantifiable, however a large element of inference
goes into the interpretation of seismic profiles, because:
Seismic profiles are NOT cross sections because the vertical
scale is two-way travel time, not thickness.
Reflector horizons needn't be lithologic boundaries. Layers with
high concentrations of chert nodules make nice reflectors, for
instance.
The resolution of seismic stratigraphy is low. A single seismic
pulse on a seismic profile may be up to 150 m. thick. (right)
As with so much else in stratigraphy, the ability to amass large quantities of information compensates for the
uncertainty inherent in the information. In this case, patterns that are likely to be connected to stratigraphy can be
observed at great depths in unexposed rock on land or beneath the sea, into which no well has been bored.
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10. 1/6/13 GEOL342 - Sedimentation and Stratigraphy
Of course, if well-log or
outcrop information is also
available, seismic reflectors
can reliably be connected to
known lithologies. By this
means we have learned that
marine sediments tend to
contrast strongly with
continental ones. (right)
The presence of petroleum
can be revealed by
anomalous horizontal
reflectors indicating the
interface of petroleum and
water, or by a brightening of
the profile caused by the
presence of gas.
Cornell University, through the Consortium on Continental Reflection Profiling (COCORP) has used seismic
methods to profile major orogenies. Among the interesting results: Whereas the traditional view was that the
Piedmont and Blue Ridge had deep crustal roots, it develops that they are underlain by extensive thrust faults
and have actually been thrust onto Paleozoic sediments.
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11. GEOL342 - Sedimentation and Stratigraphy
Seismic sequences: The geometry of
unconformities that truncate beds is
sufficiently distinctive to be identifiable in
seismic profiles, allowing identification of
seismic sequences - unconformity
bounded "packages" whose presence is
revealed by seismic reflections. Indeed,
the development of sequence stratigraphy
has gone hand-in-glove with that of
seismic stratigraphy, because only
seismic methods can identify sequence
boundaries on a large scale.
When connected to lithologic
information, these can be correlated with
age to identify sea level cycles. (right)
For many, the hope has been that these
would be caused by global eustatic sea
level change, enabling their use in global
sequence stratigraphy. In 1977, Vail,
Mitchum, and Thompson published a
summation of first and second order sea
level curves based on major
unconformities.
Second-order cycles appeared to be
markedly asymmetric, because of the
depositional asymmetry of transgression
and regressions in which transgressions are erosional, but sediment can continue to aggrade up during
regressions. Identifying onlap and offlap of sediments onto continents, enabled Haq and colleagues to develop
an adjusted curve showing sea level over the last 200 my.
As your text makes clear, the reliability and usefulness of the Vail curve is controversial.
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