Structural geology of the Mesozoic Miers Bluff Formation and crosscutting Paleogene dikes (Livingston Island, South Shetland Islands, Antarctica) – Insights into the geodynamic history of the northern Antarctic Peninsula

摘要: Abstract The Antarctic Peninsula has been part of a magmatic arc since at least Jurassic times. South Shetland Islands archipelago forms this arc, but it was separated from the following Pliocene opening Bransfield Strait. Dikes are widespread throughout and particularly accessible on Hurd Livingston Island. host rocks for dikes represented by Miers Bluff Formation, which overturned limb large-scale fold oriented 63/23 NW. orientation minor structures indicates axis NNE–SSW (24/0). Structural analysis their shows that tectonic regime similar to other parts only changes stress field occurred during dike emplacement. Based crosscutting relationships geochemical data, six early Paleocene late Eocene intrusive events can be distinguished Peninsula. In contrast calc-alkaline Islands, majority tholeiitic affinity. Nd Pb isotope data indicate significant crustal component, initial activity. Plagioclase 40Ar/39Ar whole rock K–Ar ages show emplacement peaked Lutetian (48.3 ± 1.5, 47.4 ± 2.1, 44.5 ± 1.8 43.3 ± 1.7 Ma) also further northeast King George Dike intrusion continued Island until Priabonian (37.2 ± 0.9 Ma). type magma sources (mantle, slab, crust sediment) did not change, though relative contributions varied with time. During Cretaceous Early Paleogene times, including situated southwest Patagonia; final separation America before Eocene. Thus, geological evolution is related as much development Patagonia Antarctica, needs considered within history southernmost America.