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Effects of slab-window, alkaline volcanism, and glaciation on thermochronometer cooling histories, Patagonian Andes

  • Southern Patagonia is a prime example of ongoing oceanic ridge collision and slab-window formation sustained over several million years. The impact of these phenomena on the thermal structure and exhumation of the crust have been mainly assessed with low-temperature thermochronology of bedrock samples. Here, we infer thermal histories from new and existing thermochronological data from the region of most recent ridge collision. In particular, we evaluate the potential far-reaching thermal effects of the evolving slab window, which have previously been considered responsible for patterns of late Miocene reheating associated with back-arc alkaline volcanism. Our model results define protracted cooling since similar to 15 Ma and stepwise exhumation since the late Miocene. The pattern of stepwise exhumation closely matches the onset of Patagonian glaciation at 7 Ma and the successive pulse of glacial incision coeval with neotectonic activity since 3-4 Ma that are also documented by independent geological and geomorphological evidence inSouthern Patagonia is a prime example of ongoing oceanic ridge collision and slab-window formation sustained over several million years. The impact of these phenomena on the thermal structure and exhumation of the crust have been mainly assessed with low-temperature thermochronology of bedrock samples. Here, we infer thermal histories from new and existing thermochronological data from the region of most recent ridge collision. In particular, we evaluate the potential far-reaching thermal effects of the evolving slab window, which have previously been considered responsible for patterns of late Miocene reheating associated with back-arc alkaline volcanism. Our model results define protracted cooling since similar to 15 Ma and stepwise exhumation since the late Miocene. The pattern of stepwise exhumation closely matches the onset of Patagonian glaciation at 7 Ma and the successive pulse of glacial incision coeval with neotectonic activity since 3-4 Ma that are also documented by independent geological and geomorphological evidence in the region. Importantly, our findings challenge the recently suggested lack of glacial erosion and incision since 5 Ma in this region. Furthermore, in contrast to previous modelling studies, we find that the available data do not evidence a previously proposed northward-propagating heating event associated with alkaline volcanism. We hypothesize that the anomalous alkaline volcanism in the Patagonian back-arc might be related to trench-orthogonal tears aligned with transform faults in the subducting plate. The substantial differences from the previous modelling procedure on some of the same samples is demonstrated to result from an important lack of convergence in model runs. (C) 2019 Elsevier B.V. All rights reserved.zeige mehrzeige weniger

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Metadaten
Verfasserangaben:Viktoria GeorgievaORCiDGND, Kerry GallagherORCiDGND, Artur SobczykORCiD, Edward SobelORCiDGND, Taylor F. SchildgenORCiD, Todd EhlersORCiDGND, Manfred StreckerORCiDGND
DOI:https://doi.org/10.1016/j.epsl.2019.01.030
ISSN:0012-821X
ISSN:1385-013X
Titel des übergeordneten Werks (Englisch):Earth & planetary science letters
Verlag:Elsevier
Verlagsort:Amsterdam
Publikationstyp:Wissenschaftlicher Artikel
Sprache:Englisch
Datum der Erstveröffentlichung:07.02.2019
Erscheinungsjahr:2019
Datum der Freischaltung:11.03.2021
Freies Schlagwort / Tag:Patagonian Andes; apatite (U-Th)/He; apatite fission track; inverse thermal modelling; slab window; thermochronology
Band:511
Seitenanzahl:13
Erste Seite:164
Letzte Seite:176
Fördernde Institution:German Science Foundation (DFG)German Research Foundation (DFG) [STR Grant Program [ERC 615703]
Organisationseinheiten:Mathematisch-Naturwissenschaftliche Fakultät / Institut für Umweltwissenschaften und Geographie
DDC-Klassifikation:5 Naturwissenschaften und Mathematik / 55 Geowissenschaften, Geologie / 550 Geowissenschaften
Peer Review:Referiert
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