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Questions tagged [stratigraphy]

Stratigraphy is the study of rock strata and their intrepretation in term of absolute or relative age.

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Assessing graded bedding in metamorphosed pelitic sediments

I have the following image of metasedimentary outcrop from a Proterozoic continental rift-fill sequence: The middle layer has a pelitic composition and contains abundant cordierite porphyroblasts (...
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What are these basal rip up clasts in North Dakota?

Ther's an graph that appears that the KT asteroid turned the rocks into rubble 3000 km away, else there was a rain of big rocks from the sky. What are the rip up clasts and what is the way they were ...
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Difference between Proterozoic Nagari Quartzite and Gulcheru Quartzite

The Eparchean Unconformity forms the boundary between Proterozoic Nagari Quartzite and Archean Granite. Now, the Gulcheru Quartzite marks the onset of sedimentation , after Eparchean Unconformity in ...
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What did tunnel digging teach us about the formation of chains of mountains?

Since tunnelling is like making a giant horizontal core sample, what did the analysis of the extracted rocks teach us? Is the inside homogeneous or layered, are there "deformations", etc?
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Can we call the Precambrian eons (i.e. Archaic and Proterozoic) eras?

A diagram in a book I have places Archaic and Proterozoic under "eras". Is such naming correct? ICS says they are eons, so do most sources I could find, but a 1979 volume of "Treatise on ...
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Does seismic anisotropy follow stratigraphy?

This question is in the context of velocity model building for reflection seismic imaging (between 0km and 10km in a sedimentary basin). This is really a rock physics question disguised as an imaging ...
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Boundary problems in stratigraphy

What do geologists mean when they say - Cambrian/Precambrian Boundary problems or Cretaceous/Tertiary boundary problems?
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Methods and Software for Interpolating/Modelling of Stratigraphic Well Data in 2D/3D

I have some geologic well data. The lithologies have been interpreted, and stratigraphic columns have been drawn. The columns have been adjusted for elevation, and correlation has been done between ...
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Relative dating of intrusion

I am quite new to geology and have a realtive dating problem which I am a bit unsure of. I know very well the principle of superposition, principle of cross-cutting, etc., but am still a little bit ...
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There is soil in Archean? [closed]

Following a mobilista approach over geological time, and considering the Earth's internal heat as responsible for tectonic regime, which was involved in the "Permobile type" during the early times of ...
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What are 'articulate shells'?

I can not really find a definition, not even in a geologic dictionnary: What are articulate (resp. inarticulate) shells? To be more specific, the term is related to tsunami deposits (tsunamite).
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What makes pollen varieties useful index fossils?

What makes pollen varieties useful index fossils? Should pollen not be a poor index fossil?
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Why pro-gradation occurs along coastal environments?

I am currently studying the deposition process in coastal environments and I came across a point which I do not understand concerning grading of grain size. According to "Petroleum Geology by North F....
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How accurate is the law of superposition?

Recently I started being more interested in the rational details of the sciences (... being often challenged about them by a creationist friend) and one of the creationist 'theories' I've encountered ...
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Lithologic and hydrostratigraphic logs for the Deccan volcanic province, India

I need data on depth/thickness of of different lithologic units under Deccan Volcanic Province in MP, Maharashtra and Gujarat. For this if anyone can help in providing help in obtaining well log data ...
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where are the thickest limestone layers on earth ? (CaCO3)

What is the maximum thickness of limestone layers on earth? (Limestone or any other biochemical sedimentary rocks, for example chalk or coral reefs.)
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The youngest and oldest source rock for hydrocarbons in economic quantities

Most famous and productive source rocks for hydrocarbons are Paleozoic or Mesozoic, but there are also examples from the Neogene. Time is needed for the rock to reach the right depth and temperature ...
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Incised valleys and hydrocarbon potential

The Wikipedia page on sequence stratigraphy states: Sandstone bodies associated with incised valleys are good hydrocarbon reservoirs. Can anyone elaborate on this statement and the reason behind ...
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Are there any geological periods found on top of each other that have dinosaurs of that period with in them?

In diagrams, It is common to depict geological periods to be directly on top of each other with fossils of that period within them. When looking for evidence of this, I have only found examples of ...
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Nuclear testing and the Anthropocene, a chemostratigraphic link?

The Anthropocene is described by Wikipedia as an informal geologic chronological term for the proposed epoch that began when human activities had a significant global impact on the Earth's ...
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Width of strata in stratigraphic column

I am trying to understand whether there is one "standard" meaning of the width of represented strata in stratigraphic columns, but I can find nothing online or in my geology books. I notice that, ...
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Why is the concept of “mass extinction” a relatively recent development in geology?

The concept of "mass extinctions", with its catastrophic connotations, is a relatively recent development in the geological sciences. It evolved in the early 1980s, driven by two landmark publications ...
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Is the Principle of Fossil Succession accurate?

After wondering on the validity of the principle of Original Horizontality, I'm now focusing on the principle of fossil succession. This principle states that : Fossils of species that did not ...
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Is the Principle of Original Horizontality a good indicator?

Still reading a course on datation over multiple stratums that may have setting up the Earth's crust, I'm meeting for the first time the principle of original horizontality Steno. Is this theory safe?...
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Are there secondary causes of sea level change?

Aside from the fraction of water stored as ice on land and temperature of the water, are there other factors that change sea level, and if so what are is the magnitudes of the these changes? For ...
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Determining a rock age using volcanic ash layer

I wanted to know if volcanic ash deposits found in the geologic record are most useful in correlating the age of rock layers if the volcanic ash was distributed over a large area during a short period ...
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How to interpret the use of late and early Tertiary from older literature?

When reading older papers how should I interpret the use of "Late Tertiary" and "Early Tertiary"? Would these periods equate to Paleogene and Neogene, or was there a different accepted boundary age ...
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Is there a database of the geologic/stratigraphic units of France?

Is there a page where I can look up rock unit definitions for France similar to: https://www.bgs.ac.uk/lexicon/home.cfm http://www.bgr.de/app/litholex/index.php I did some searching for this, but ...
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Which are the biggest methodological differences between the archaeological and geological approaches to stratigraphy?

Stratigraphy, or study of rock or soil layers (strata), was originally introduced as a branch of geology. However, it is often applied in other disciplines, especially in archaeology and paleonthology....
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How have global sedimentation rates changed over the last billion years?

Do we have a graph of how sedimentation rates changed over time?