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Shivam Sharma posted an Question
August 31, 2020 • 16:28 pm 30 points
  • CSIR NET
  • Earth Sciences

A stratigraphic column, consisting of formations a, b and c (from bottom to top), having mutual gradational contacts, is characterized as follows: c-shore-face

A stratigraphic column, consisting of formations A, B and C (from bottom to top), having mutual gradational contacts, is characterized as follows: C-shore-face sandstone B- inner to middle shelf sandstone-shale alternation A-outer shelf mud with occasional thin sandstone What does this stratigraphic column indicate transgression or regression? Justify. Which formation has the sandstone with the least matrix, and why? Which formation has the most rounded sand grains?

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    Rahul kumar best-answer

    1. The Stratigraphic column indicates marine regression because finer sediments (mud) are gradually changing into sand i.e., a coarsening upward sequence. Coarsening upward sequence is characterized by marine regression. 2. Formation C will have least amount of matrix. The matrix amount will be least in C because of continuous action of swash and backwash of current. Swash and backwash current will remove the matrix (finer grains) from sand. 3. Formation C will have most rounded grains because of swash and backwash action of current. Due to the current action process like attrition between the sand grains will occur and hence the sediments will become rounded.

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