Crustal growth of the Antarctic Peninsula by accretion, magmatism and extension

Abstract

A subduction-accretion model incorporating new geophysical data is presented to explain the geology of the Antarctic Peninsula from late Palaeozoic to Cenozoic time. According to the model, the peninsula consists of overlapping accretionary, magmatic and extensional regimes that were diachronous across the peninsula and have built the crust to its present form. The crust, which contains a small proportion of sialic basement, was mainly formed by accretionary and magmatic processes and modified to its present shape by extension. The Gondwanide Orogeny for the Antarctic Peninsula is interpreted in terms of the accretionary processes.

New geophysical compilations link crustal block motion to Jurassic extension and strike-slip faulting in the Weddell Sea Rift System of West Antarctica

“…A rifted or strike slip margin to the Weddell Sea Rift System may have been present in Jurassic times, or the NWMP structures may have extended into the region of the present day Antarctic Peninsula. However, overprinting by Cretaceous magmatism and orogenic processes largely obscures the older structures within the Antarctic Peninsula (Burton- Johnson and Riley, 2015;Storey and Garrett, 1985;Vaughan et al, 2012). In addition, the precise position of the Antarctic Peninsula relative to the WSRS in Jurassic times is not well constrained (Miller, 2007).…”

Cretaceous and Cenozoic vegetation of Antarctica integrating the fossil wood record

“…The Antarctic Peninsula is the remnant of a continental-margin magmatic arc of MesozoicCenozoic age (Storey & Garrett 1985). Formed as a result of subduction of the palaeo-Pacific Plate beneath the western margin of the Antarctic Peninsula, it has good exposures of magmatic-arc, accretionary complex, and foreand back-arc regions.…”

Thermochronologic constraints on the tectonic evolution of the western Antarctic Peninsula in late Mesozoic and Cenozoic times

“…In Mesozoic and Cenozoic times, it has been affected by tectonic processes related to the subduction of the Phoenix plate (oceanic lithosphere from the southeastern Pacific Ocean) below the Antarctic and South American plates. Models for the tectonic evolution of the studied area generally consider diachronous crustal growth by accretion and magmatism in the overriding plate, which was almost continuous from the early Mesozoic Gondwanide to the late Mesozoic and Cenozoic Andean activities (e.g., Storey & Garrett, 1985;Vaughan & Storey, 2000), forming a coherent structural domain. The outcropping basement in northern Graham Land is formed by a turbidite complex of Late Carboniferous to ?Jurassic age, the Trinity Peninsula Group (TPG; e.g., Smellie, 1991;Hervé at al., 2006), representing a former active continental margin in the Antarctic plate.…”