The low-grade basement at Península La Carmela, Chilean Patagonia: new data for unraveling the pre-Permian basin nature of the Eastern Andean Metamorphic Complex

The Eastern Andean Metamorphic Complex at Península La Carmela (48°50’S) consists of quartz-rich metaturbiditic sequences with tectonic slices pillow metabasalt bodies deformed under low-grade metamorphic conditions. Previous and new detrital zircon U–Pb geochronological data from metasandstones indicate a preferred early Carboniferous maximum depositional age the protolith, interpreted youngest single grains several metasedimentary rocks in area. wide spectrum ages Carmela, includes Neoproterozoic-early Paleozoic components subordinate ancient (> 2200 Ma). They were sourced cratonic regions and/or reworked material older successions plutonic belts southwestern Gondwana (e.g., North Patagonian Deseado massifs or Tierra del Fuego Igneous Complex). metabasalts have geochemical affinities normal mid-oceanic ridge basalts island-arc tholeiites Nb–Ta negative anomalies, derived depleted mantle source (εNdt + 6 7.5). In consideration that ocean island basalt are reported, we propose tectonically juxtaposed within pre-Permian accretionary wedge an active continental margin, after development arcs back-arc marginal basins.