Provenance of late Palaeozoic metasediments of the Patagonian proto-Pacific margin (southernmost Chile and Argentina) |
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Authors: | Carita Augustsson Heinrich Bahlburg |
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Institution: | 1.Geologisch-Pal?ontologisches Institut, Westf?lische Wilhelms-Universit?t,Muenster,Germany;2.Zentrallaboratorium für Geochronologie, Mineralogisches Institut,Westf?lische Wilhelms-Universit?t,Muenster,Germany |
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Abstract: | In this provenance study of late Palaeozoic metasediments of the Eastern Andean Metamorphic Complex (EAMC) along the south
Patagonian proto-Pacific margin of Gondwana, the palaeogeological setting of the continental margin in Devonian–Carboniferous
and Permian times is reconstructed. The study is based on detrital heavy mineral contents, chemical compositions of tourmaline
grains, and whole rock element and Nd-Sr isotopic compositions. Element and isotopic compositions reveal that Devonian–Carboniferous
metaturbidites deposited before the development of a Late Carboniferous–Permian magmatic arc along the margin were mainly
fed from felsic, recycled, old continental rocks. The last recycling phase involved erosion of metasediments that were exposed
in Patagonia. Feeder systems to the basin cut either through epidote-rich or garnet-rich metasediments. In Permian time, EAMC
metaturbidites were deposited next to the evolving magmatic arc and were derived from felsic, crustal rocks. Two provenance
domains are recognised. The metasediments of the northern one are chemically similar to those of the Devonian–Carboniferous
metasediments. This domain was fed from the metasedimentary host rocks of the magmatic arc. The southern domain probably was
fed from the arc proper, as indicated mainly by the dominance of metaplutonic lithic fragments, abundant detrital biotite,
and the major element composition of the metasediments. |
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Keywords: | Provenance Geochemistry Heavy minerals Palaeozoic Patagonia |
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