Graduate Student Seminars

Please join us for two graduate student seminars this Friday December 7 in rm 155 Geology:

3:30 pm – Romain Gougeon, PhD Candidate

EARLY CAMBRIAN ORIGIN OF THE SHELF SEDIMENT MIXED LAYER

The mixed layer of modern oceans is a zone of fully homogenized sediment resulting from bioturbation. The mixed layer is host to complex biogeochemical cycles that directly impact ecosystem functioning, affecting ocean productivity and marine biodiversity. However, the timing of appearance of a mixed zone at the sediment-water interface remains uncertain within a 100 million year interval stretching from the early Cambrian to the late Silurian, hindering palaeontological and geochemical studies of this key milestone in Earth evolution. In our study we provide detailed evidence from the Global Stratotype Section and Point (GSSP) of the basal Cambrian in the Burin Peninsula of Newfoundland, Canada, demonstrating that a mixed layer of similar structure to that of modern ocean was well established in shallow marine settings by the early Cambrian (approximately 529 my ago). In contrast with modern seafloors, Ediacaran marine sediment surfaces were pervasively coated with resistant microbial mats that acted as geochemical filter between the underlying sediment and overlying seawater. Significant reductions in the prevalence of microbial mats coupled with widespread bioturbation and associated bioirrigation would have permitted increasingly free-interchange between surface sediments and the water column, dramatically changing fluid chemistry of both of these regimes. Our analysis of bioturbation in this section shows that substrate exploitation in the Ediacaran was restricted to non-penetrative horizontal grazing of microbial mats, whereas a mixture of superficial mat grazing trails, undermat-mining burrows and small penetrative burrows characterize the Fortunian and the establishment of the marine sediment mixed layer is the main innovation of Cambrian Age 2. These findings imply that the mixed layer was one of the early innovations of the Phanerozoic and an integral part of the Cambrian explosion.

4:00 pm – Kamal Abo Jnah, MSc candidate

Processing and Interpreting of the Teapot Dome 3-D seismic dataset (Wyoming U.S.A.)

This project focuses on processing the Teapot Dome 3-D seismic dataset (Wyoming, U.S.A.) and performing some techniques of interpretation with it. Data processing was performed by using ProMAX and Geotomo software. After making some experiments with processing parameters, I performed geometry assignment, static correction, velocity analysis, normal and dip moveout (NMO and DMO) corrections, stacking, residual static, and post-stack migration. Ongoing work includes interpreting the data in order to identify the horizons and visualize the geological and geotechnical data which have been done by OpendTect software.