Detrital zircon SHRIMP U–Pb age study of the Cordillera Darwin Metamorphic Complex of Tierra del Fuego: sedimentary sources and implications for the evolution of the Pacific margin of Gondwana

Abstract

The Cordillera Darwin Metamorphic Complex in the southernmost Andes includes a basement of probable Palaeozoic age, a mid-Jurassic and younger volcano-sedimentary cover, and a suite of Jurassic granites, all of which were jointly metamorphosed during the Cretaceous. Detrital zircon ages presented here show that some of the amphibolite-facies metamorphic rocks previously mapped as basement have a Jurassic protolith. Overall the detrital zircon age patterns for samples of the Cordillera Darwin basement differ from those of the Madre de Dios Terrane of the western Patagonian Andes with which they had been correlated; instead, they are more comparable with those from the Eastern Andes Metamorphic Complex, which apparently developed in a passive margin setting. The paucity of Cambrian detrital zircons indicates that the meta-igneous basement of the Magallanes foreland basin of central and northern Tierra del Fuego was not the main source of detritus for the protolith of the Cordillera Darwin Metamorphic Complex. The possibility is envisaged that the Magallanes Fagnano transform fault boundary between the Scotia and South America plates resulted from reactivation of an older, pre-Jurassic suture zone between the basement terranes of north–central Tierra del Fuego and Cordillera Darwin. Supplementary material: Geographical coordinates of analysed samples, sensitive high-resolution ion microprobe U–Th–Pb analytical data and representative cathodoluminescence images of zircon grains analysed are available at http://www.geolsoc.org.uk/SUP18397 .

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

“…They lie outside the range of crystallization ages for the Cambrian-earliest Ordovician granites of the Ross-Delamerian orogen of the Transantarctic Mountains and southern Australia (Foden et al 2006). Similarly, they do not correspond to the Cambrian ages recently determined from the Tierra del Fuego basement (Hervé et al 2010) or to Late Precambrian-Cambrian granites in southern Africa (Scheepers & Armstrong, 2002). The granites are older than ages reported from orthogneiss in southern Graham Land and western Palmer Land (Harrison & Piercy, 1991;Millar, Pankhurst & Fanning, 2002;Milne & Millar, 1991).…”

“…The pattern is one commonly seen along the Gondwana margin, particularly in the SW Pacific region (Ireland et al 1998), extending into the Ellsworth-Whitmore Mountains ) and also represented in pre-Carboniferous rocks of Patagonia (Pankhurst et al , 2006. Drilling has also revealed Cambrian granodioritic gneiss in the basement of Tierra del Fuego (Hervé et al 2010;Pankhurst et al 2003;Söllner, Millar & Herve, 2000). These occurrences support an extension of the Pampean Orogen into eastern Patagonia including the southern Deseado terrane, a region regarded as an allochthonous crustal block by Pankhurst et al (2006) that had amalgamated (or reunited) with northern Patagonia by the Permian period.…”

“…These occurrences support an extension of the Pampean Orogen into eastern Patagonia including the southern Deseado terrane, a region regarded as an allochthonous crustal block by Pankhurst et al (2006) that had amalgamated (or reunited) with northern Patagonia by the Permian period. Hervé et al (2010) reported evidence of a high-grade metamorphic event of Permian age in Tierra del Fuego.…”

Petrological vestiges of the Late Jurassic-Early Cretaceous transition from rift to back-arc basin in southernmost Chile: New age and geochemical data from the Capitán Aracena, Carlos III, and Tortuga ophiolitic complexes

“…This is consistent with detrital zircon ages reported for fine-grained turbidites from the Zapata and Yaghan formations Hervé et al, 2010), indicating maximum depositional ages of Hauterivian for the sedimentary successions and a 25 myr minimum time period of continuous sedimentation in the Rocas Verdes basin.…”

South Georgia and Gondwana's Pacific Margin: Lost in translation?

“…3a). Consistent with this view, detrital zircon compositions from Tierra del Fuego (Barbeau et al, 2009;Hervé et al, 2010) show that the Paleozoic metasediments there accumulated in sedimentological communication with the interior of Gondwana. Basement rocks in Graham Land may be similar (Millar et al, 2002), consistent with it forming a northwestern continuation of this rim as shown.…”