Upper Mesozoic flysch of Tierra del Fuego and South Georgia Island: A sedimentologic approach to lithosphere plate restoration

Research Article| April 01, 1978 Upper Mesozoic flysch of Tierra del Fuego and South Georgia Island: A sedimentologic approach to lithosphere plate restoration R. D. WINN, JR. R. D. WINN, JR. 1Department of Geology & Geophysics, University of Wisconsin, Madison, Wisconsin 94706 Search for other works by this author on: GSW Google Scholar Author and Article Information R. D. WINN, JR. 1Department of Geology & Geophysics, University of Wisconsin, Madison, Wisconsin 94706 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1978) 89 (4): 533–547. https://doi.org/10.1130/0016-7606(1978)89<533:UMFOTD>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation R. D. WINN; Upper Mesozoic flysch of Tierra del Fuego and South Georgia Island: A sedimentologic approach to lithosphere plate restoration. GSA Bulletin 1978;; 89 (4): 533–547. doi: https://doi.org/10.1130/0016-7606(1978)89<533:UMFOTD>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The South Georgia Island segment of the North Scoria Ridge is interpreted as having once been adjacent to Tierra del Fuego, South America. The upper Mesozoic graywackes, mudstones, and tuffs of South Georgia (Cumberland Bay and Sandebugten strata) and Tierra del Fuego (Yahgan Formation and Tekenika Beds) are the infill of a marginal basin that formed between the South American continent and an active calc-alkalic arc. The former arc site is now occupied by the Patagonian batholith; ophiolites represent the former basin sea floor.Sediment gravity flow fabrics, sedimentary structures, and bedding styles and relatively deep-water trace fossils (Phycosiphon, Helminthopsis, Taenidium, Zoophycos, Chondrites, Scalarituba?, Lophoctenium?) indicate deposition on submarine fans. Paleocurrent and petrographic analyses indicate bilateral infilling of the basin. The only known possible sources for the Sandebugten sandstones are silicic volcanic and interbedded sedimentary rocks of the Jurassic Tobifera Formation of South America; this evidence indicates former juxtapositioning of South Georgia and Tierra del Fuego. The Sandebugten-type sandstones and the Jurassic volcanic rocks have abundant quartz and plagioclase, uncommon potassic feldspar, and essentially no pyroxene and amphibole. Lithic fragments in these sandstones have identical counterparts in the Jurassic volcanic and sedimentary rocks. The Yahgan and Cumberland Bay clastic rocks were eroded chiefly from calc-alkalic volcanic rocks positioned south of their depositional areas. The latter sandstones are made up dominantly of andesite and dacite tuff and flow fragments. Plagioclase is common; quartz, ferromagnesian minerals, and mafic volcanic fragments are uncommon. Basin closure and deformation occurred during the Late Cretaceous Andean orogeny when the rocks were metamorphosed to prehnite-pumpellyite grade. South Georgia was translated relatively eastward, probably as the result of collision of the Drake Passage spreading zone with the continent during Oligocene to Miocene time. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.