Sedimentology of shallow-marine depositional systems and deposits

Current Research Projects - S. Dashtgard

My research focuses on the sedimentology of shallow-marine depositional systems and deposits. Within this overarching theme, I am currently overseeing research programs in three areas, with much of my recent research being conducted in convergent-margin basins.

1) My main area of research involves developing a sequence stratigraphic framework for the lower Nanaimo Group, and reconstructing the early evolution of the (forearc) Nanaimo Basin along the western margin of North America (the Baja, BC  hypothesis). The lower Nanaimo Group is exposed in outcrops throughout eastern Vancouver Island, B.C., and is part of the Cretaceous-aged Nanaimo Basin (and the more regionally defined Georgia Basin). Our research on the Nanaimo Group involves descriptions of outcrops, detrital zircon analyses, and some thin section petrology. Outcrop descriptions are used to define stratigraphically significant surfaces that bound stratal packages, and detrital zircon analyses are used to estimate depositional ages and sediment provenance of Nanaimo Group strata.

2) I am also directing research defining climate-induced cyclicity in Pliocene through to Pleistocene strata in the Western Foreland Basin, Taiwan. This work is outcrop-based and involves descriptions of outcrops, sediment geochemistry (d13C and C:N), drone imagery, and development of 3D outcrop models.  We also correlate rock record observations to processes in the modern-day Taiwan Strait. We are particularly interested in identifying tropical cyclone (typhoon) deposits and understanding changes in the typhoon signal at Milankovich scales of climate change.

3) Finally, I continue to conduct research on fluvio-tidal strata both in modern-day systems and the rock record. In modern systems, I  am involved is a series of projects focused on the Fraser River, B.C., and the Gironde Estuary, France. In the rock record, I am mainly focused on the McMurray Fm in Alberta and Saskatchewan. Work on fluvio-tidal strata and associated environments includes sedimentology, ichnology, and stratigraphy, and assessing lateral changes in the character of deposits across the fluvio-tidal transition. We also use palynology, sediment geochemistry (d13C), XRF, and detrital zircon to address specific questions that arise.