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IntroductionThe record of detrital zircons in pre-Jurassic metasedimentary complexes from southern Patagonia provided novel record to constrain the provenance sources of sediments and the maximum depositional ages of turbiditic successions that spread along the western margin of Gondwana (Hervé et al., 2003, 2010; Augustsson and Bahlburg 2003a. 2006, 2008; Castillo et al., 2015). The pre-Jurassic continental basement of southern Patagonian Andes (Fig.1A) is constituted by the Eastern Andean Metamorphic Complex (EAMC) and the Cordillera Darwin Metamorphic Complex (CDMC), which are located east and north, respectively, of the Patagonian batholiths. Those units located west of the batholiths are the Chonos Metamorphic Complex (CMC) and the Duque de York Complex (DYC).On the basis of detrital zircon analyses (Hervé et al., 2003; Augustsson et al., 2003a; Augustsson et al., 2008) the EAMC includes sedimentary components deposited between the late Devonian and early Carboniferous, as well as younger turbidites deposited during the Permian and Triassic. Older successions show Ordovician, Devonian and Early Carboniferous peaks of detrital zircons and the younger rocks show peaks of Permian zircons with variable proportions of Carboniferous, Devonian, Ordovician and Cambrian grains. The detrital zircon spectra the CDMC is characterized by Mississippian peaks (of ca. 330-340 Ma) with a variable proportion of Devonian, Ordovician, Cambrian, and Neo-to Meso-proterozoic components (Hervé et al., 2010). Detrital zircons ages in the CMC show characteristic peaks of Upper Triassic with variable proportions of Permian, Carboniferous, Devonian and Cambrian components (Hervé et al., 2003). Detrital zircon age data from rocks of the DYC shows a dominant peak of Permian zircons (ca. 270-290 Ma) (Hervé et al., 2003; Sepúlveda et al., 2010; Castillo et al., 2015). These rocks also comprise subordinate Carboniferous and Ordovician zircons populations, the latter becoming an important contribution in the southernmost outcrops of this unit.The statistical analysis of detrital zircon age distribution patterns is a useful tool to establish the tectonic setting of the basin in which the sediments were deposited (Cawood et al. 2012). This study performed a statistical analyzed of detrital zircons of the above mentioned tectono-metamorphic units. The Cumulative Distribution Function (CDF) and the relation between the crystallization vs. depositional ages of detrital zircons from Paleozoic metamorphic complexes are shown in Figure 1. Based on these results is possible to discriminate between different geological settings (cf. Cawood et al., 2012) and consider the crystallization age (CA)for a detrital zircon grain and the depositional age (DA), is important mentioned that the depositional age is different for each metasedimentary complex, the maximum depositional for EAMC is 364 Ma, and minimum depositional age is 250 Ma; CMC is 213 Ma; DYC to close 234 Ma (Thomson and Hervé; Hervé et al., 2008, 2010). Discussions and conclusionsThe EAMC record detrital zircon patterns with a behavior akin to convergent and collisional settings, only one sample fall in the field of the passive setting (Fig.1A, B). The results for the detrital zircons shows that CA-DA > 100 Ma is major to 30% to CA-DA 150 Ma. The data support the deposition of sedimentary successions in a Permian-Triassic fundamentally convergent to collisional settings if we are considered the minimum age for sedimentation close to 250 Ma. According to the occurrence of metaplutonic lithic fragments, detrital biotite, and the major element composition of the metasediments the basin probably was fed from the arc proper and their country rocks (Augustsson et al., 2008).The curves resulting from detrital zircons in the CMC show a value of CA-DA >100 Ma is major to 30 % in general, linked to deposition in a convergent setting (Fig.1D). This consistent with deposition of turbiditic successions in the trench of a convergent margin and its subsequent evolution at the base of an accretionary complex in a subduction setting. The Duque de York (DYC) comprises two samples with CA-DA> 100 Ma major to 30 % (Fig. 1E). The curve is adjusted as expected for deposits formed in a convergent setting. The notorious predominance of Permian zircons reveals that the source areas were extensively covered by volcanic rocks and probably shallow-level granitoids.The CDMC show a wide spectrum of curves. Although mostly are akin to convergent margin one is located in the transition between collision and extensional settings (Fig.1F). The results reveal the internal complexities of the CDMC formed and exhumed after the juxtaposition of several tectonic slices during the Andean orogeny (Late Cretaceous). The geological evidence and similarities between CDF curves of the CMC and DYC, in which detrital zircons with crystallization age are close to the time of deposition, agree with previous studies indicating their deposition in a convergent margin. Also for the younger components of the EAMC (those with Permian to Triassic depositional age). At this point is important to elucidate the nature of basins in which sediments were transported. Depending on the dynamic of plate interaction at convergent margins, controlled by factors such as the angle of convergence and subduction, depocenters could be localized in the forearc and backarc settings. Finally, from the detrital zircon patterns and CDF curves, we propose that outcrops of the DYC are also found near the eastern margin of the Patagonian batholiths (sample FO0718). Other samples (FF9905, SE9908) show identical CDF curves to those of the DYC but different detrital zircon patterns (cf. Hervé et al., 2003).ReferencesAugustsson C and Bahlburg H., 2003a. Active or passive margin? Geochemical and Nd isotope constraints of metasedimentsin the backstop of a pre-Andean accretionary wedge in southernmost Chile (46°30?S-48°30S). In: McCann T, Saintot A (eds).Tracing tectonic deformation using the sedimentary record, vol 208. Geological Society, Special Publication, London, pp 253?268. Augustsson, C., Bahlburg, H., 2008. Provenance of late Palaeozoic metasediments of the Patagonian proto-Pacific margin(southernmost Chile and Argentina). International Journal of Earth Science, 97, 71-88. Augustsson, C., Munker, C., Bahlburg, H.,Fanning, C.M., 2006. Provenance of late Palaeozoic metasediments of the SW South American Gondwana margin: a combined U?Pb and Hf-isotope study of single detrital zircons. J Geol Soc Lond 163:983?995. Calderón, M., Hervé, F., Fuentes, F., Fosdick, J.,Sepúlveda, F., Galaz, G., 2016. Tectonic Evolution of Paleozoic and Mesozoic Andean Metamorphic Complexes and the Rocas VerdesOphiolites in Southern Patagonia. Geodynamic Evolution of the Southernmost Andes, Springer Earth System Sciences. Castillo, P.,Fanning, C.M., Hervé, F., Lacassie, J.P. 2015. Characterisation and tracing of Permian magmatism in the south-western segmentof the Gondwana margin; U?Pb age, Lu-Hf and O isotopic compositions of detrital zircons from metasedimentary complexes ofnorthern Antarctic Peninsula and western Patagonia. Gondwana Res (in press) Cawood, P.A., Hawkesworth, C.J., Dhuime, B.,2012. Detrital zircon record and tectonic setting. Geology, 40, 875-878. Hervé, F, Fanning, CM, Pankhurst, RJ., 2003. Detrital zirconage patterns and provenance of the metamorphic complexes of southern Chile. J S Am Earth Sci 16:107?123. Hervé, F., Calderón,M., Fanning, MC., Kraus, S., Pankhurst, R. 2010. SHRIMP chronology of the Magallanes Basin basement, Tierra del Fuego: Cambrianplutonism and Permian high-grade metamorphism. Andean Geology 37 (2). p.253-275. Sepúlveda, F., Palma-Heldt, S., Hervé, F.,Fanning, C.M., 2010. Permian depositional age of metaturbidites of the Duque de York Complex, southern Chile: U-Pb SHRIMPdata and Thomson, S., and Hervé, F., 2002. New time constraints for the age of metamorphism at the ancestral Pacific Gondwanamargin of south Chile ( 42-52°S). Revista Geologica de Chile, vol, 29, No.2., p. 255-271.