Sedimentary basins are the depressions in the earth's crust where loose particles accumulate and finally lithified to form sedimentary rocks. Basins are particularly attractive to geoscientists from time immemorial due to the wealth hidden here in the form of oil, gas, coal etc. In this document you will find the types of basins, basin-fill types, methods of basin analysis and so on.
Boundary problems between :-
Precambrian/Cambrian
Permian/Triassic
Cretaceous/Tertiary
Neogene/Quaternary
Stratigraphic boundaries are determined by one or more of geological events such as volcanic activity, sedimentation, tectonism, paleo-environments & evolution of life.
Faunal records have played major role in determining the boundaries of the Phanerozoic units.
The other geological events are dated on the evidence of fossil records.
This is my presentation on the tectonic control of sediments.
It includes the effects of tectonics either direct or indirect on sediments and sedimentation.
Sedimentation along various plate boundaries.
Few examples as evidence from Pakistan (the Siwalik Group) and Argentina (Fiambala Basin)
Boundary problems between :-
Precambrian/Cambrian
Permian/Triassic
Cretaceous/Tertiary
Neogene/Quaternary
Stratigraphic boundaries are determined by one or more of geological events such as volcanic activity, sedimentation, tectonism, paleo-environments & evolution of life.
Faunal records have played major role in determining the boundaries of the Phanerozoic units.
The other geological events are dated on the evidence of fossil records.
This is my presentation on the tectonic control of sediments.
It includes the effects of tectonics either direct or indirect on sediments and sedimentation.
Sedimentation along various plate boundaries.
Few examples as evidence from Pakistan (the Siwalik Group) and Argentina (Fiambala Basin)
CLASSIFICATION OF ORE DEPOSITS
The Mixture of ore minerals are gangue minerals form an Ore deposit. The ore
deposits are generally found enclosed within the country rocks. The ore deposits
are formed in many different ways. Depending upon the process that may
operate to produce them, the ore deposits may be classified as follow:
Magmatic ore deposits.
Sublimation ore deposits.
Pegmatitic ore deposits.
Contact metasomatic ore deposits.
Hydrothermal ore deposits
Cavity filling deposits.
Replacement deposits.
Sedimentation ore deposits.
Evaporation ore deposits.
Residual and mechanical concentration deposits
Metamorphic ore deposits.
MAGMATIC ORE DEPOSITS:
The magmatic ore deposits are the magmatic products which crystallize from
magmas. The magmatic ore deposits are classified as follows:
o Early magmatic deposits
o Late magmatic deposits
Early magmatic deposits:
Early magmatic deposits are formed during the
early stage of the magmatic period. In this case the
ore minerals crystallize earlier than the rock
silicates. The Minerals of Nickel, Chromium, and
Platinum are usually found as early magmatic
deposits. The early magmatic deposits can be sub
divided into two groups:
o Dissemination deposits
o Segregation deposits
Dissemination deposits:
When magma crystallizes
conditions, a granular igneous rock is formed. In
such a rock early formed crystals of
may occur in dissemination.
Segregation deposits:
Magmatic segregation deposits are
formed as a result of gravitative
crystallization differentiation. In
case, the ore mineral which crystallize
early, get ocean-trated on a particular
part of igneous part. The ore deposits
thus formed are known as “Segregation
deposits”.
rly under seated
ore minerals
such
Late Magmatic Deposits:
The ore deposits which are formed to
called late magmatic deposits. The late magmatic deposits contain those ore
minerals which have crystallized at rather low temperature from the residual
magma. The magma which is left after crystallization of early for
is called residual magma. This magma frequently contains many ore minerals. The
late magmatic deposits include most of the magmatic deposits of iron and
titanium ores, these deposits are almost always associated with mafic igneous
rocks.
SUBLIMATION DEPOSITS:
Sublimation is a very minor process of formation of ore deposits. Sublimation
deposits contain only those minerals which have been volatilized by hear and
subsequently redeposit in the same form at low temperature and pressure. The
sublimation deposits are found associated with Volcanoes and Fumaroles. Sulfur
of this origin has been mined in Japan, Italy, and Mexico.
Kutch is an East-west Oriented pericraton Rift basin Situated between Nagar Parkar Fault in North and Kathiawar Uplift in South.
Here we will discuss Geology and its Sequence Stratigraphy.
CLASSIFICATION OF ORE DEPOSITS
The Mixture of ore minerals are gangue minerals form an Ore deposit. The ore
deposits are generally found enclosed within the country rocks. The ore deposits
are formed in many different ways. Depending upon the process that may
operate to produce them, the ore deposits may be classified as follow:
Magmatic ore deposits.
Sublimation ore deposits.
Pegmatitic ore deposits.
Contact metasomatic ore deposits.
Hydrothermal ore deposits
Cavity filling deposits.
Replacement deposits.
Sedimentation ore deposits.
Evaporation ore deposits.
Residual and mechanical concentration deposits
Metamorphic ore deposits.
MAGMATIC ORE DEPOSITS:
The magmatic ore deposits are the magmatic products which crystallize from
magmas. The magmatic ore deposits are classified as follows:
o Early magmatic deposits
o Late magmatic deposits
Early magmatic deposits:
Early magmatic deposits are formed during the
early stage of the magmatic period. In this case the
ore minerals crystallize earlier than the rock
silicates. The Minerals of Nickel, Chromium, and
Platinum are usually found as early magmatic
deposits. The early magmatic deposits can be sub
divided into two groups:
o Dissemination deposits
o Segregation deposits
Dissemination deposits:
When magma crystallizes
conditions, a granular igneous rock is formed. In
such a rock early formed crystals of
may occur in dissemination.
Segregation deposits:
Magmatic segregation deposits are
formed as a result of gravitative
crystallization differentiation. In
case, the ore mineral which crystallize
early, get ocean-trated on a particular
part of igneous part. The ore deposits
thus formed are known as “Segregation
deposits”.
rly under seated
ore minerals
such
Late Magmatic Deposits:
The ore deposits which are formed to
called late magmatic deposits. The late magmatic deposits contain those ore
minerals which have crystallized at rather low temperature from the residual
magma. The magma which is left after crystallization of early for
is called residual magma. This magma frequently contains many ore minerals. The
late magmatic deposits include most of the magmatic deposits of iron and
titanium ores, these deposits are almost always associated with mafic igneous
rocks.
SUBLIMATION DEPOSITS:
Sublimation is a very minor process of formation of ore deposits. Sublimation
deposits contain only those minerals which have been volatilized by hear and
subsequently redeposit in the same form at low temperature and pressure. The
sublimation deposits are found associated with Volcanoes and Fumaroles. Sulfur
of this origin has been mined in Japan, Italy, and Mexico.
Kutch is an East-west Oriented pericraton Rift basin Situated between Nagar Parkar Fault in North and Kathiawar Uplift in South.
Here we will discuss Geology and its Sequence Stratigraphy.
Advanced petrology ( tectonic and sedimentation).pptx
How the sedimentation where taken and the kind of transportation process is going on? The role of plate tectonic settings in sedimentation.
Tectonic Basin and its classification:
Dickinson's Classification
Kingston Classification
Ingersoll's Classification
Bally and Snelson's Classification
This tacklesabout locating epicenter,3 typesof plate boundaries hotspot.
A ppt presentation for module 1 in 1st quarter in grade 10sciencein the Philippines.
Feel free tomessage mefor any corrections/suggestions forimprovement.
A report on wireline log interpretation with emphasis on hydrocarbon of Salda...Shahadat Saimon
The report focuses on wireline log interpretation of the Saldanadi structure, Bangladesh. Available data includes Gamma ray log, SP log, Density log, Neutron log and Resistivity log based on which lithology and hydrocarbon potentiality of the gas field is evaluated.
This report includes the practical training experience at different divisions of BAPEX (Bangladesh Petroleum Exploration and Production Company Limited), Bangladesh.
Underground mining methods + swot analysis of maddhapara graniteShahadat Saimon
This document will provide information on two important topics of Mining.
One is the different methods used in underground mining along with underground mine anatomy and other is the SWOT (Strength, Weakness, Opportunity and Threat) analysis of Maddhapara Granite, Parbatipur, Dinajpur, Bangladesh.
Unconventional petroleum resource potentiality in the bengal basinShahadat Saimon
Unconventional petroleum resource is rather a new term in the world of hydrocarbon where petroleum is extracted from the source rock itself without expecting any trap, reservoir and migration pathways. As of Bangladesh’s perspective, we have only been successful in exploiting structural traps (saying anticlinal traps would be more perfect). In this growing industrialization, exploring unconventional resources or new petroleum plays is a must to meet with the current demand, as Bangladesh is likely to run out of indigenous fuel by 2030s.
A description on the petroleum system of BangladeshShahadat Saimon
This is a broad knowledge about the overall petroleum system in the Bengal Basin and each of it's provinces. The proved source rock, reservoir rock, trapping mechanisms are also included.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
The increased availability of biomedical data, particularly in the public domain, offers the opportunity to better understand human health and to develop effective therapeutics for a wide range of unmet medical needs. However, data scientists remain stymied by the fact that data remain hard to find and to productively reuse because data and their metadata i) are wholly inaccessible, ii) are in non-standard or incompatible representations, iii) do not conform to community standards, and iv) have unclear or highly restricted terms and conditions that preclude legitimate reuse. These limitations require a rethink on data can be made machine and AI-ready - the key motivation behind the FAIR Guiding Principles. Concurrently, while recent efforts have explored the use of deep learning to fuse disparate data into predictive models for a wide range of biomedical applications, these models often fail even when the correct answer is already known, and fail to explain individual predictions in terms that data scientists can appreciate. These limitations suggest that new methods to produce practical artificial intelligence are still needed.
In this talk, I will discuss our work in (1) building an integrative knowledge infrastructure to prepare FAIR and "AI-ready" data and services along with (2) neurosymbolic AI methods to improve the quality of predictions and to generate plausible explanations. Attention is given to standards, platforms, and methods to wrangle knowledge into simple, but effective semantic and latent representations, and to make these available into standards-compliant and discoverable interfaces that can be used in model building, validation, and explanation. Our work, and those of others in the field, creates a baseline for building trustworthy and easy to deploy AI models in biomedicine.
Bio
Dr. Michel Dumontier is the Distinguished Professor of Data Science at Maastricht University, founder and executive director of the Institute of Data Science, and co-founder of the FAIR (Findable, Accessible, Interoperable and Reusable) data principles. His research explores socio-technological approaches for responsible discovery science, which includes collaborative multi-modal knowledge graphs, privacy-preserving distributed data mining, and AI methods for drug discovery and personalized medicine. His work is supported through the Dutch National Research Agenda, the Netherlands Organisation for Scientific Research, Horizon Europe, the European Open Science Cloud, the US National Institutes of Health, and a Marie-Curie Innovative Training Network. He is the editor-in-chief for the journal Data Science and is internationally recognized for his contributions in bioinformatics, biomedical informatics, and semantic technologies including ontologies and linked data.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
insect taxonomy importance systematics and classification
Sedimentary basins
1. GS-522 Assignment Md. Shahadat Hossain, Roll-1651
Sedimentary Basins Page 1
Sedimentary Basins
What are sedimentary basins?
Sedimentary basins can be defined as a low area in the Earth’s crust of tectonic origin, in which sediments
accumulate into successions of hundreds to thousands of meters in thickness over areas of thousands to
millions of square kilometers and finally lithified to form compact sedimentary rocks irrespective of its
source material. For sediment to accumulate in a basin there must be a vertical interval between the water
surface and the basin bottom, termed as accommodation space.
Basin forming mechanism:
Sedimentary basins are a depression of some kind, capable of trapping sediment. Subsidence of the upper
surface of the crust must take place to form such a depression. Mechanisms that can generate sufficient
subsidence to create basins include crustal thinning, mantle-lithosphere thickening, sedimentary and
volcanic loading, tectonic loading, subcrustal loading, asthenospheric flow and crustal densification.
Thick sedimentary sequences may form where the weight of the sediment itself causes isostatic
depression of the crust.
Factors controlling sediment supply and basin fill:
The rate at which a basin is infilled is a function of several variables in the basin and in the drainage
catchment area:
Variables within the basin include the environment and its energy level, that is, the ability of
wind, wave, and tidal currents to transport, segregate and deposit sediment.
Other critical intra-basinal variable include changes in sea level which affect the top of the
accommodation space and tectonism, principally rate of subsidence which affects the floor of the
accommodation space.
The rate of sediment supply into a basin is dependent on the type and intensity of weathering,
erosion and transportation within the drainage catchment area. Most of these variables are closely
related to climate.
Vegetation is another important controlling parameter, closely related to climate.
The chemical composition and physical parameters of the rock in the source area will also play an
important part.
2. GS-522 Assignment Md. Shahadat Hossain, Roll-1651
Sedimentary Basins Page 2
Sedimentary basin types and their tectonic settings (after Boggs, 2006):
Basin types & Tectonic settings Example
Divergent
Settings
Terrestrial rift valleys Rio Grande Rift (New Mexico)
Proto-oceanic rift troughs Red Sea
Intraplate
Settings
Continental rises and terraces East coast of USA
Continental embankments Mississippi Gulf Coast
Intracratonic basins Chad Basin (Africa)
Continental platforms Barents Sea (Asia)
Active ocean basins Pacific Ocean
Oceanic islands, aseismic ridges and plateaus Emperor-Hawaii seamounts
Dormant ocean basins Gulf of Mexico
Convergent
Settings
Trenches Chile Trench
Trench-slope basins Central America Trench
Fore-arc basins Sumatra
Intra-arc basins Lago de Nicaragua
Back-arc basins Marianas
Retro-arc foreland basins Andes foothills
Remnant ocean basins Bay of Bengal
Peripheral foreland basins Persian Gulf
Piggyback basins Peshawar Basin (Pakistan)
Foreland intermontane basins Sierras Pampeanas basins (Argentina)
Transform
Settings
Transtensional basins Salton Sea (California)
Transpressional basins Santa Barbara Basin (California) (foreland)
Transrotational basins Western Aleutian fore-arc (?)
Intracontinental wrench basins Quaidam Basin (China)
Fig. 1: Diagram showing the interplay between the variables that control sediment supply
and accommodation space (Selley, 2000).
3. GS-522 Assignment Md. Shahadat Hossain, Roll-1651
Sedimentary Basins Page 3
Hybrid
Settings
Aulacogens Mississippi Embayment
Impactogens Baikal Rift (Siberia) (distal)
Successor basins Southern Basin and Range (Arizona)
Basin classification:
All the above mentioned different tectonic settings are the areas where sediment can accumulate and at a
simple level, three main settings of basin can be recognized (Nichols, 2009):
1. Basins associated with regional extension within and between plates;
2. Basins related to convergent plate boundaries;
3. Basins associated with strike-slip plate boundaries.
In the following discussion the main basin types and the transitions between them are considered in terms
of the plate tectonic setting.
1. Basins related to lithospheric extension:
Divergent tectonic settings are regions of Earth where tectonic plates are separating. In the early stages of
tectonic extension, rifts form and are typically sites of continental sedimentation. If the stretching
continues, the continental lithosphere may rupture completely and the injection of basaltic magmas results
in the formation of new oceanic crust within the zone of extension. The principal types related to
extensional settings are:
a. Rift basins: In regions of extension, continental crust fractures to produce rifts which are
structural valleys bound by normal faults. The axis of the rift lays more-or-less perpendicular to the
direction of the stress. The down-faulted blocks are referred to as graben and the up-faulted areas as
horsts. The bounding faults may be planar or listric and if the displacement is greater on one side they
form asymmetric valleys referred to as half-graben. Uplift on the flanks of rifts due to regional high heat
flow and the effect of relative movements on the rift-bounding faults creates local sediment sources for
rift valleys (Fig. 2a).
b. Intracratonic basins: Areas of broad subsidence within a continental block (craton) away
from plate margins or regions of orogeny are known as intracratonic basins. The cratonic crust is typically
ancient and with low relief. The area may be very large but the amount of subsidence is low and the rate
is very slow. Subsidence is so slow that there seems to have been no depression of the upper surface of
the lithosphere so depositional environments are mostly the same as those in surrounding areas; the
succession is just thicker (Fig. 2b).
4. GS-522 Assignment Md. Shahadat Hossain, Roll-1651
Sedimentary Basins Page 4
Fig. 2: Types of basins related to crustal extension, (2a) Rift basin, (2b) Intracratonic basin, (2c) Proto-
oceanic basin, (2d) Passive continental and Oceanic basin (Nichols, 2009).
c. Proto-oceanic troughs: the transition from rift to ocean: Continued extension within
continental crust leads to thinning and eventual complete rupture. Basaltic magmas rise to the surface in
the axis of the rift and start to form new oceanic crust. Where there is a thin strip of basaltic crust in
between two halves of a rift system the basin is called a proto-oceanic trough. The basin will be wholly or
partly flooded by seawater by the time this amount of extension has occurred and the trough has the form
of a narrow seaway between continental blocks. Sediment supply to this seaway comes from the flanks of
the trough which will still be relatively uplifted (Fig. 2c).
d. Passive margins: The regions of continental crust and the transition to oceanic crust along the
edges of spreading ocean basins are known as passive margins. The term ‘passive’ is used in this sense as
the opposite to the ‘active’ margins between oceans and continents where subduction is occurring.
Morphologically, the passive margin is the continental shelf and slope and the clastic sediment supply is
largely from the adjacent continental land area. The climate, topography and drainage pattern on the
continent therefore determines the nature and volume of material supplied to the shelf. Passive margins
are important areas of accumulation of both carbonate and clastic sediment (Fig. 2d).
e. Oceanic basins: Basaltic crust formed at mid-oceanic ridges is hot and relatively buoyant. As
the basin grows in size new magmas created along the spreading ridges, older crust moves away from the
hot mid-ocean ridge. Cooling of the crust increases its density and decreases relative buoyancy, so as
crust moves away from the ridges, it sinks (Fig. 2d).
2a 2b
2c 2d
5. GS-522 Assignment Md. Shahadat Hossain, Roll-1651
Sedimentary Basins Page 5
2. Basins related to subduction:
Subduction related settings (Fig. 3) are features of seismically active continental margins such as the
modern Pacific Ocean margin. These settings are characterized by a deep sea trench, an active volcanic
arc and an arc-trench gap separating the two. The most important depositional sites in subduction related
settings are deep sea trenches, forearc basins that lie within the arc-trench gap and backarc or marginal
basins that lie behind the volcanic arc in some arc-trench systems.
Fig. 3: Types of basins related to subduction (Nichols, 2009).
a. Trenches: Ocean trenches are elongated gently curving troughs that form where an oceanic
plate bends as it enters a subduction zone. The inner margin of the trench is formed by the leading edge of
the overriding plate of the arc–trench system. Trenches formed along margins flanked by continental crust
tend to be filled with sediment derived from the adjacent land areas. Transport of material into trenches is
by mass flows, especially turbidity currents (Fig. 3).
b. Accretionary prisms: The strata accumulated on the ocean crust and in a trench are not
necessarily subducted along with the crust at a destructive plate boundary. The sediments may be wholly
or partly scraped off the downgoing plate and accrete on the leading edge of the overriding plate to form
an accretionary complex or accretionary prism. These prisms or wedges of oceanic and trench sediments
are best developed where there are thick successions of sediment in the trench (Fig. 3).
c. Forearc basins: The inner margin of a forearc basin is the edge of the volcanic arc and the
outer limit is the accretionary complex formed on the leading edge of the upper plate. The width of a
forearc basin will therefore be determined by the dimensions of the arc–trench gap which is in turn
determined by the angle of subduction. The main source of sediment to the basin is the volcanic arc and,
if the arc lies in continental crust, the hinterland of continental rocks (Fig. 3).
d. Backarc basins: Extensional backarc basins form where the angle of subduction of the
downgoing slab is steep and the rate of subduction is greater than the rate of plate convergence. The
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principal source of sediment in a backarc basin formed in an oceanic plate will be the active volcanic arc.
Backarc basins are typically underfilled, containing mainly deep water sediment of volcaniclastic and
pelagic origin (Fig. 3).
3. Basins related to strike-slip tectonism:
Zones of localised subsidence and uplift due to a network of transform faults create topographic
depressions for sediment to accumulate and the source areas to supply them. Most basins in strike-slip
belts are generally termed transtensional basins and are formed by three main mechanisms:
First, the overlap of two separate faults can create regions of extension between them known as
pull-apart basins. Such basins are typically rectangular or rhombic and are unusually deep (Fig. 4a).
Second, where there is a branching of faults, a zone of extension exists between the two branches
forming a basin (Fig. 4b).
Third, the curvature of a single fault strand results in bends that are either restraining bends
(locally compressive) or releasing bends (locally extensional): releasing bends form elliptical zones of
subsidence (Fig. 4c).
Fig. 4: Types of basins related to strike-slip tectonism, (4a) Pull-apart basin, (4b) Basin formed at
fault branch, (4c) Basin formed at releasing bend (Nichols, 2009).
Basin fill types:
Basin type Basin fill
Rift basins Coarse to fine siliciclastics, usually nonmarine; often lacustrine sediments; interbedded basalts.
Intracratonic
basins
Shallow water cratonal sediments (carbonates, shales, sandstones).
Passive margin
basins
Shallow marine siliciclastics and carbonates of the continental shelf, thickening seaward.
These sediments pass gradually or abruptly into deeper marine fine sediments of the
continental slope and rise often grading or interfingering seaward into deep-marine coarse and
fine siliciclastics or resedimented carbonates in the form of turbidites building submarine fans
at the base of the slope and filling the deepest parts of the ocean basin to form abyssal plains.
Trenches Varies from thin pelagic sediments (fine abyssal muds, volcanic ash) to thick arc-derived
coarse siliciclastics and volcaniclastics.
4b
4a
4c
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Forearc basins Nonmarine siliciclastic fluvial to deltaic deposits at the arcward margin pass seaward into deep
marine siliciclastics, all interbedded with arc-derived volcanic flows and pyroclastics.
Backarc basins Sedimentation is strongly asymmetric with most of the sediment supplied from the active
magmatic arc. From cores collected during the Deep Sea Drilling Project (DSDP) nine
sediment types were found (Klein, 1985) in the back-arc basins of the western Pacific: Debris
flows, Submarine fan systems, Pelagic clays, Biogenic pelagic silica sediments, Biogenic
pelagic carbonates, Resedimented carbonates, Pyroclastics.
Pull-apart basins Filled by thick nonmarine to marine, coarse to fine clastics, often as alluvial fans passing into
lake deposits or into deposits of restricted marine environments. In some cases thick marine
turbidites fill the distal parts of the basin.
Remnant basins Very thick and highly varied with strong lateral facies changes; usually fluvial at the margins,
commonly passing into deep marine sediment-gravity-flow deposits.
Sedimentary basin analysis:
Sedimentary basin analysis is the aspect of geology that considers all the controls on the accumulation of
a succession of sedimentary rocks to develop a model for the evolution of the sedimentary basin as a
whole. The purpose of basin analysis is to interpret basin fills to better understand sediment provenance,
paleogeography, depositional environments and geologic history and to evaluate the economic potential
of basin sediments.
Techniques of sedimentary basin analysis:
Analyzing the characteristics of sediments and sedimentary rocks that fill basins and interpreting these
characteristics in terms of sediment and basin history, demands a variety of sedimentological and
stratigraphic techniques. These techniques require the acquisition of data through outcrop studies and
subsurface methods that can include deep drilling, magnetic polarity studies and geophysical exploration.
In this section, we look briefly at the more common techniques of basin analysis.
a. Measuring stratigraphic sections: To interpret Earth history through study of sedimentary
rocks requires that we have detailed, accurate information about the thicknesses and lithology of the
stratigraphic successions. To obtain this information, appropriate stratigraphic successions must be
measured (Fig. 5a) and described in outcrop and/ or from subsurface drill cores and cuttings. The process
also involves describing the lithology, bedding characteristics and other pertinent features of the rocks.
Thus, measuring and describing stratigraphic sections is commonly the starting point for many geologic
studies.
b. Preparation of stratigraphic maps and cross sections: This can be done preparing the below
mentioned maps/ daigrams:
1. Stratigraphic cross sections (Fig. 5b)/ Fence diagrams (Fig. 5c)
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2. Structure-contour maps (Fig. 5d)
3. Isopach maps (Fig. 5e)
4. Paleogeologic maps
5. Lithofacies maps (Fig. 5f)
6. Computer-generated maps
Fig. 5: Techniques of basin analysis, (5a) measuring stratigraphic successions, (5b) cross section, (5c)
fence diagram, (5d) structure-contour maps, (5e) isopach maps, (5f) lithofacies maps.
c. Paleocurrent analysis: Paleocurrent analysis is a technique used to determine the flow
direction of ancient currents that transported sediment into and within a depositional basin which reflects
the local or regional paleoslope and also the direction in which the sediment source area or areas lay.
Further, it aids in understanding the geometry and trend of lithologic units. Paleocurrent analysis is
5a
5b
5c
5d 5e
5f
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accomplished by measuring the orientation of directional features such as sedimentary structures (e.g.,
flute casts, ripple marks, cross-beds) or the long-axis orientation of pebbles.
d. Provenance studies: Analysis of the particle composition of siliciclastic mineral assemblages
(and rock fragments) provides a method of working backward to understand the nature of the source area.
We commonly refer to such study as provenance study where provenance is considered to include the
following: (1) the lithology of the source rocks, (2) the tectonic setting of the source area and (3) the
climate, relief, and slope of the source area. Provenance studies provide important information about the
paleoclimatology and paleogeography of the basin setting.
d. Geophysical studies: Geophysical investigations, including both seismic and paleomagnetic
studies of various kinds play an important role in basin analysis. Seismic techniques are used to document
the regional structural trends and overall basin geometry as well as to identify local structural features
such as anticlines and faults that may provide traps for hydrocarbons. The most widespread application of
paleomagnetism in basin analysis is the study of magnetic polarity reversals as a tool for correlation.
Applications of sedimentary basin analysis:
a. Interpreting geologic history: One major goal of basin analysis is simply to develop a better
understanding of Earth history as recorded in particular depositional basins. Through analysis of
sedimentary textures, structures, particle and chemical composition, fossils and the stratigraphic
characteristics of sedimentary rocks (as revealed by physical, biological, paleomagnetic and seismic
reflection characteristics), geologists are able to interpret the important tectonic and sedimentologic
events that transpired to generate and fill a particular sedimentary basin. Thus, these various kinds of
basin studies, allow geologists to interpret past tectonic, climatic, and sedimentologic events and
conditions (including source area characterization and interpretation of depositional environments) to
reconstruct the paleogeography and paleogeology of Earth during specific times in the past.
a. Economic Applications: The second goal of basin analysis is to use the principles and
techniques described above to evaluate the economic importance of sedimentary rocks and identify
economically exploitable deposits of minerals or fossil fuels. Basin analysis finds its greatest economic
application in the fields of petroleum geology and to a lesser extent, hydrogeology. In spite of the fact that
petroleum geologists have been trying for many years to locate petroleum (hydrocarbon) accumulations,
no successful method has yet been developed for direct detection of hydrocarbon deposits. To find an oil
or gas deposit, geologists must (1) explore basins that have the right conditions for the formation and
migration of hydrocarbons and (2) locate a suitable trap such as a structural anticline, in which the
hydrocarbons may have accumulated. Basin analysis to the petroleum geologist thus means locating
within depositional basins suitable source rocks, reservoir rocks and traps. To do this successfully calls
into play most of the principles of sedimentology and stratigraphy,
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References:
Boggs S., 2006, Principles of Sedimentology and Stratigraphy, 4th
Edition, Pearson Prentice Hall, USA.
Klein G. D., 1985, The Control of Depositional Depth, Tectonic Uplift and Volcanism on Sedimentation
Processes in The Back-Arc Basins of the Western Pacific Ocean, Journel of Geology, vol. 93, p. 1-25.
Nichols G., 2009, Sedimentology and Stratigraphy, 2nd
Edition, Blackwell Publishing, UK.
Selley R. C., 2000, Applied Sedimentology, 2nd
Edition, Academia Press, USA.
Tucker, 2003, Sedimentary Petrology, 3rd
Edition, Blackwell Publishing, UK.