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Application Of Modern Foraminiferal Assemblages To Paleoenvironmental Reconstruction: Case Studies From Coastal And Shelf Environments, Christian Haller
Application Of Modern Foraminiferal Assemblages To Paleoenvironmental Reconstruction: Case Studies From Coastal And Shelf Environments, Christian Haller
USF Tampa Graduate Theses and Dissertations
The aim of paleoenvironmental studies is to reconstruct characteristics of the past environment from fossil assemblages preserved in sedimentary strata. Thus, studies of modern surface assemblages, quantitatively correlated to the environmental parameters, are required before reliable interpretations can be made. For this dissertation, two different techniques were applied in two case studies: a reconstruction making use of a benthic foraminiferal transfer function from the intertidal marshes in the eastern Mississippi Sound, Alabama/Mississippi, and a qualitative reconstruction of ocean current activity on the Western Australian shelf.
Modern salt-marsh foraminifera were collected from Grand Bay, Pascagoula, Fowl River, and Dauphin Island across …
Australian Great Barrier Reef Initiation Timing Constrained By Seaward Shallow-Water Sediment Drift Architecture (Odp Leg 194, Marion Plateau), Stephen P. Obrochta
Australian Great Barrier Reef Initiation Timing Constrained By Seaward Shallow-Water Sediment Drift Architecture (Odp Leg 194, Marion Plateau), Stephen P. Obrochta
USF Tampa Graduate Theses and Dissertations
I resolved the sedimentary architecture of a shallow water (< 500 m), hemipelagic sediment drift located on the Marion Plateau, seaward and downstream of the Great Barrier Reef (GBR). The drift responded increasingly to sea-level fluctuations during the Pleistocene. In the early Pleistocene, local climatic variations introduce a precessional rhythm to drift architecture that is out of phase with sea level-forced cyclicity. Beginning in the mid Pleistocene, sea level variations dominate drift architecture, with the highest carbonate and terrigenous fluxes likely occurring during highstand and transgression, respectively. At the sea-level transgression of MIS 15 and subsequent isotope stages, the phasing of maximum terrigenous flux corresponds to sea-level transgression, indicating siliciclastic sediment accumulated on the continental shelf behind an exposed barrier reef during the lowstand of MIS 16 and was remobilized by rising sea-level. These sedimentological data indicate GBR initiation occurred during MIS 17. The normal polarity exhibited by the central GBR and thick section of underlying sediments rules out initiation during MIS 19.
MIS 17 was the first of the asymmetric glacial cycles characteristic of the Late Pleistocene. If the Florida Keys and Belize barrier reef initiations were indeed simultaneous with that of the GBR, then the changing nature of cyclicity in global sea level and climatic fluctuations likely influenced the initiation of the world's major, modern barrier reefs.