24-Pet-A1 Principles of Stratigraphy and Sedimentation · December 2014
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
EGBC National Exam — Petroleum Engineering, 98-Pet-A1 Principles of Stratigraphy & Sedimentation, 2014-Dec. 3 hours duration; closed book, no calculator permitted. The paper has three parts: Part A1 (Questions 1–7, sedimentary processes, 5 marks each, answer any 4 of 7 for 20 marks), Part A2 (Questions 8–15, brief/multiple-choice, 3 marks each, answer any 5 of 8 for 15 marks), and Part B (Questions 16–24, stratigraphy, 5 marks each, answer any 6 of 9 for 30 marks) – a 65-mark maximum.
Reference texts: Boggs, S. Jr., Principles of Sedimentology and Stratigraphy, 5th ed., Pearson (grain texture, sediment transport, bedforms, carbonate/evaporite systems, sequence stratigraphy, unconformities, stratigraphic principles); Tucker, M.E., Sedimentary Petrology, 3rd ed., Blackwell (carbonate classification, diagenesis, dolomitization); Nichols, G., Sedimentology and Stratigraphy, 2nd ed., Wiley-Blackwell (fluvial systems, sequence stratigraphy, stratigraphic units); Reading, H.G. (ed.), Sedimentary Environments: Processes, Facies and Stratigraphy, 3rd ed., Blackwell (facies models, trace fossils); Selley, R.C. & Sonnenberg, S., Elements of Petroleum Geology, 3rd ed., Academic Press (source rocks, reservoir quality); International Commission on Stratigraphy, International Chronostratigraphic Chart (geological time scale).
Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.
A chronostratigraphic (time-rock) unit is a body of rock – a physical, mappable material – that was formed during a specific interval of geologic time; it is defined by its boundaries (usually a Global Boundary Stratotype Section and Point, GSSP) and is described using material verbs ("was deposited," "contains"). A geochronologic (time) unit is the corresponding abstract interval of TIME itself during which that rock formed – it has no physical existence, cannot be touched or sampled, and is described using temporal language ("occurred during," "lasted from…to").
| Chronostratigraphic (rock) unit | Geochronologic (time) unit |
|---|---|
| Erathem | Era |
| System | Period |
| Series | Epoch |
| Stage | Age |
Every chronostratigraphic unit has a directly corresponding geochronologic unit and vice versa – the two are simply the rock and the time referred to by the same boundaries, described from opposite perspectives. Example (chronostratigraphic): the Devonian System is the body of rock that accumulated worldwide during a specific interval of time. Example (geochronologic): the Devonian Period is that interval of time itself (roughly 419 to 359 million years ago) – the rock (System) exists in outcrop and core; the time (Period) does not, it is simply elapsed duration.
