18-Geol-A3 Sedimentation and Stratigraphy · May 2016
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
EGBC National Exam — Geological Engineering, 04-Geol-A3, Sedimentation & Stratigraphy, 2016-May. Closed book, no calculator, 3 hours. Part 1 (Questions 1–12, Sedimentology and Sedimentary Processes) instructs "Answer eight questions of your choice" (8 × 5 = 40 marks) and Part 2 (Questions 13–19, Stratigraphy and Sedimentary Basin Analysis) instructs "Answer five of the following seven questions" (5 × 5 = 25 marks), for a maximum attainable grade of 65/65.
Reference texts: Nichols, Sedimentology and Stratigraphy, 2nd ed. (depositional environments, facies models, flow regime and bedforms, carbonate platforms, sequence stratigraphy, biostratigraphic correlation); Boggs, Petrology of Sedimentary Rocks, 2nd ed. (sandstone/carbonate classification, diagenesis, provenance); Selley & Sonnenberg, Elements of Petroleum Geology (turbidite reservoirs, trace-fossil facies context).
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.
All four biozone types are defined below.
A taxon-range biozone is the body of strata representing the total known stratigraphic (and hence temporal) range of occurrence of a single, chosen taxon — bounded below by that taxon's first appearance and above by its last appearance, wherever it is found. An interval biozone is the body of strata between two specified, defined biostratigraphic horizons (datums) — commonly the first appearance of one index taxon and the first appearance of another — without necessarily corresponding to the total range of any single taxon; it is essentially a "gap-filler" unit bounded by two independently defined datums. A lineage biozone (also called a phylozone) is the body of strata containing specimens that represent a specific, defined segment of an evolving phylogenetic (ancestor-descendant) lineage, bounded by two points along that lineage's morphological evolution — it requires that the evolutionary trend itself be well documented and directional. An assemblage biozone is the body of strata characterized by a distinctive, naturally occurring association of three or more taxa considered together as a group, defined by the total character of that assemblage rather than by the individual range limits of any one constituent taxon — two assemblage zones can therefore share some of the same taxa yet be distinguished by differing overall composition.
