Metamorphic rocks in the Antarctic Peninsula region

Abstract

AbstractThe distribution of metamorphic rocks in the Antarctic Peninsula region, new quantitative peak pressure–temperature data along the Antarctic Peninsula, and a literature review on the current knowledge of metamorphic conditions in the Antarctic Peninsula region have been compiled into a single metamorphic map. The pressure–temperature data for the Antarctic Peninsula indicate (1) burial of supracrustal rocks to low to mid-crustal depth along the eastern and western side of the Antarctic Peninsula and on some islands adjacent to the western side of the peninsula; (2) uplift of lower- to mid-crustal metamorphic rocks along major shear and fault zones; and (3) a reversed succession of metamorphic grades for the western domain of the Antarctic Peninsula region compared to the eastern domain along the Eastern Palmer Land Shear Zone (EPLSZ) of the Antarctic Peninsula. The metamorphic data are consistent with oblique convergence between Alexander Island (the Western Domain), Palmer Land (Central Domain) and the Gondwana margin (the Eastern Domain), supporting a model of (1) exhumation and shearing of the higher pressure rocks from central western (up to 9.4 kbar) and from northeast (7 kbar to 9 kbar) Palmer Land, (2) the exhumation and shearing of low to medium pressure rocks in western Palmer Land and along the Eastern Palmer Land Shear Zone, and (3) shallow burial and subsequent exhumation of sediments of the Gondwana margin along the Eastern Palmer Land Shear Zone. Based on the high-amphibolite grade rocks exposed in central western Palmer Land, our data also support earlier suggestions that the Eastern Palmer Land Shear Zone is the surface expression of a northwest- to west-dipping, deep-level, high-temperature crustal shear zone extending below the western part of the Central Domain of the Antarctic Peninsula.