Discussion
Features given below are diagnostic to which sedimentary environment ?
Tectonic setting : Formed in very deep water basin, trench, along ophiolites, epicratonic basins or as starved of clastic debris, accumulated thick sequences of chalk, cherts or black shales.
Geometry : Form vast, thin, tabular sheets, in fault--bounded basins it can reach thousands of meters in thickness
Typical sequence : Homogeneous, thin bedded, laminated chalk, chert or shales.
Sedimentology : Chalks, opaline silica, clay minerals are predominant, Minor authigenic minerals, volcanic and eolian dust, phosphatic fragment. Extensive bioturbation and burrowing.
Fossils : Planktonic microfossil, siliceous or phosphatic microfossils.
Answer: B
The features describe a Pelagic environment.
Pelagic sediments accumulate slowly in deep ocean basins, far from land and starved of clastic debris. They form thin, laterally continuous sheets of chalk, chert and black shale, built mostly from the shells of planktonic microfossils (calcareous ooze, radiolarian and diatom silica) with clay and wind-blown dust, which matches every feature listed.
Tidal, continental shelf and deltaic environments are shallow and supplied with sand and mud from land, so they produce cross-bedded sandstones, heterolithic beds and coarsening-upward sequences, not homogeneous chalk, chert and shale.
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development