Gondwanide continental collision and the origin of Patagonia

Abstract

18A review of the post-Cambrian igneous, structural and metamorphic history of

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

“…Granite cobbles with zircons in a similar range of ages (between 460 and 490 Ma) also occur in the basal Permian La Golondrina Formation of the Deseado Massif , but the absence of Permian detrital zircons in the matrix at View Point suggests that it is older than the La Golondrina Formation, although the clasts may be derived from a similar source. The Devonian granite clast is, within error, the same age as a granite (371 ± 4 Ma) from the southwestern part of the North Patagonia Massif (Pankhurst et al 2006). The Archaean granite has an age (3161 ± 13 Ma) and Hf isotope composition that matches closely with the Kaapvaal Craton of South Africa (Zeh, Gerdes & Barton, 2009).…”

“…Granites of very similar ages (474 ± 6 Ma to 476 ± 6 Ma) are reported from the Sierra Grande area of the North Patagonia Massif (Pankhurst et al 2006) and similar but less well constrained ages from granite in the Deseado Massif of southern Patagonia . Granitoids within this range are also reported from the Famatinian arc in the Sierras Pampeanas further to the north (Chernicoff et al 2010;Dahlquist et al 2008).…”

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

“…Here, it can be envisaged as having formed part of a wide zone of mixed heritage that accreted to, or detached from and was accreted back to, west Gondwana in Paleozoic times (Pankhurst et al, 2006). Later, the island formed part of a sheared and then passive margin on the southern fringe of the Falkland Plateau as this mixed zone became the locus of the supercontinent's breakup.…”

“…The basement of the Falkland Plateau, in contrast, consists of older, Proterozoic, metasediments intruded by granitoids that may be as young as Cambrian, exposed at Cape Meredith on the Falkland Islands, possibly also penetrated in DSDP hole 330 on Maurice Ewing Bank, and continuing west beneath the Deseado Massif to be referred to collectively as the Deseado Terrane (Pankhurst et al, 2006;Schilling et al, 2008). On the reconstruction, the basement metasediments of Tierra del Fuego, the North Scotia Ridge and South Georgia are depicted as a Paleozoic-aged autochthonous, probably accretionary, southern rim to the Deseado Terrane (Fig.…”

Zircon ages delimit the provenance of a sand extrudite from the Botucatu Formation in the Paraná volcanic province, Iraí, Brazil

“…The oldest age is 295 ± 5 Ma and the youngest is 244 ± 6 Ma (Lower Triassic). Pankhurst et al (2006) attributed the more voluminous and widespread nature of this magmatism to major access of heat to the crust following breakoff of the subducted slab after a continental collision that was initiated in Carboniferous times.…”