The eastern Palmer Land shear zone: a new terrane accretion model for the Mesozoic development of the Antarctic Peninsula

Abstract

A major ductile fault zone, the eastern Palmer Land shear zone, has been identified east of the spine of the southern Antarctic Peninsula. This shear zone separates newly identified geological domains, and indicates that during Late Jurassic terrane accretion and collision, two and possibly three separate terranes collided, resulting in the Palmer Land orogeny. The orogeny is best developed in eastern Palmer Land and eastern Ellsworth Land. There, shallow-marine sedimentary rocks of the Latady Formation, and a metamorphic and igneous basement complex of possible Lower Palaeozoic to pre-Early Jurassic age, are thrust and folded. This forms an arcuate, east-directed, foreland, fold and thrust belt up to 100 km wide and 750 km long, parallel to the axis of the Antarctic Peninsula. The newly identified Antarctic Peninsula domains include: (1) a parautochthonous Eastern Domain that represents part of the margin of the Gondwana continent, comparable to the Western Province of New Zealand, the Ross Province superterrane of Marie Byrd Land, the Eastern Series of south-central Chile, the Pampa de Agnía and Tepuel rocks of north Patagonia, and the Cordillera Darwin rocks of Tierra del Fuego, (2) a suspect Central Domain that represents an allochthonous, microcontinental, magmatic arc terrane, comparable to the Median Tectonic Zone of New Zealand, the Amundsen Province superterrane of Marie Byrd Land, and Coastal Cordillera of north Chile and (3) a suspect Western Domain, with strong similarities to the Eastern Province of New Zealand, Western Series of south-central Chile, and Chonos metamorphic complex of north Patagonia, that represents either a subduction–accretion complex to the Central Domain, or another separate crustal fragment. Although an allochthonous terrane hypothesis for the Antarctic Peninsula remains to be fully tested, this has much in common with models for the New Zealand and South American parts of the Pacific margin of Gondwana. The identification of a potential allochthonous terrane–continent collision zone allows us to define the edge of the Gondwana continent in the Antarctic Peninsula sector of the supercontinent margin, which has implications for Mesozoic reconstructions of Gondwana.

Permo-Carboniferous conglomerates in the Trinity Peninsula Group at View Point, Antarctic Peninsula: sedimentology, geochronology and isotope evidence for provenance and tectonic setting in Gondwana

“…The outliers of the Botany Bay Group suggest that both the View Point and Hope Bay areas were deformed by Early Jurassic times but evidence that the very similar Trinity Peninsula type rocks of the Miers Bluff Formation of the South Shetland Islands are of Jurassic age (Hervé et al 2006) suggest a second younger belt of sedimentation and deformation that post-dates Late Triassic deformation (Vaughan & Livermore, 2005) in the Antarctic Peninsula. The Trinity Peninsula Group may thus comprise two or more discrete sedimentary-tectonic tracts that amalgamated during the Mesozoic and collectively accreted to the magmatic Central Domain of Vaughan & Storey (2000) in Cretaceous times. Amalgamation of two or more lithologically similar but chronologically distinct sedimentary tracts is known also from the Torlesse rocks of New Zealand (Wandres & Bradshaw, 2005).…”

Chrono- and lithostratigraphy of a Mesozoic–Tertiary fore- to intra-arc basin: Adelaide Island, Antarctic Peninsula

“…Ph.D. thesis, Univ. Birmingham, 1965;1970) and later by Griffiths & Oglethorpe (1998) who were not able to place too much chronological control on the stratigraphy they proposed, but they did assign a probable Late Jurassic Vaughan & Storey (2000) and Ferraccioli et al (2006). age to the stratified rocks of Adelaide Island based on similarities to rocks from elsewhere on the west coast of the Antarctic Peninsula.…”

“…Adelaide Island sits in a geologically important position across the fore-to intra-arc sector †Author for correspondence: t.riley@bas.ac.uk of the Antarctic Peninsula, and correlations between its successions and those of Alexander Island and the Antarctic Peninsula should provide a test of terrane boundary models, timing of accretion and probability of the Western Domain being exotic (Vaughan & Storey, 2000).…”

Chariocrinus(Crinoidea: Articulata) from the Latady Formation, Behrendt and Hauberg Mountains, Ellsworth Land, Antarctica

“…The geology, structure, and sedimentology of the Latady Formation are well documented (Laudon et al 1969;Dalziel & Elliot 1973;Suárez 1976;Smellie 1981;Rowley & Williams 1982;Laudon etal. 1983;Rowley et al 1983;Vaughan & Storey 2000).…”