Pliocene-Pleistocene orographic control on denudation in northwest Argentina
- The intermontane Humahuaca Basin in the Eastern Cordillera of the northwest Argentine Andes lies leeward of an orographic barrier to easterly derived moisture. An average of >2000 mm/yr of rainfall along the eastern flanks of the barrier contrasts with <200 mm/yr in the orogen interior. Paleoenvironmental reconstructions suggest that the basin became disconnected from the foreland during the Miocene-Pliocene by the growth of fault-bounded mountain ranges. Fossil records, sedimentology, and stable isotope data imply that rerouting of the fluvial network by 4.2 Ma and reduced rainfall by ca. 3 Ma were consequences of that range uplift. Here, we present cosmogenic nuclide-derived (Be-10) paleodenudation rates from 6 to 2 Ma fluvial deposits collected from the Humahuaca Basin. Despite increased tectonic activity, our Be-10 data show a tenfold decrease in denudation rates at ca. 3 Ma, documenting a link between uplift-induced semiarid conditions and decreasing hillslope denudation rates. This new data set thus demonstrates the influence ofThe intermontane Humahuaca Basin in the Eastern Cordillera of the northwest Argentine Andes lies leeward of an orographic barrier to easterly derived moisture. An average of >2000 mm/yr of rainfall along the eastern flanks of the barrier contrasts with <200 mm/yr in the orogen interior. Paleoenvironmental reconstructions suggest that the basin became disconnected from the foreland during the Miocene-Pliocene by the growth of fault-bounded mountain ranges. Fossil records, sedimentology, and stable isotope data imply that rerouting of the fluvial network by 4.2 Ma and reduced rainfall by ca. 3 Ma were consequences of that range uplift. Here, we present cosmogenic nuclide-derived (Be-10) paleodenudation rates from 6 to 2 Ma fluvial deposits collected from the Humahuaca Basin. Despite increased tectonic activity, our Be-10 data show a tenfold decrease in denudation rates at ca. 3 Ma, documenting a link between uplift-induced semiarid conditions and decreasing hillslope denudation rates. This new data set thus demonstrates the influence of hydrological change on spatiotemporal denudation patterns in tectonically active mountain areas.…
Author details: | Heiko PingelORCiDGND, Taylor F. SchildgenORCiD, Manfred StreckerORCiDGND, Hella WittmannORCiDGND |
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DOI: | https://doi.org/10.1130/G45800.1 |
ISSN: | 0091-7613 |
ISSN: | 1943-2682 |
Title of parent work (English): | Geology |
Publisher: | American Institute of Physics |
Place of publishing: | Boulder |
Publication type: | Article |
Language: | English |
Date of first publication: | 2019/02/27 |
Publication year: | 2019 |
Release date: | 2021/03/10 |
Volume: | 47 |
Issue: | 4 |
Number of pages: | 4 |
First page: | 359 |
Last Page: | 362 |
Funding institution: | Emmy Noether Programme of the Deutsche Forschungsgemeinschaft (DFG)German Research Foundation (DFG) [SCHI 1241/1-1]; DFGGerman Research Foundation (DFG) [STR 373/34-1]; Brandenburg Ministry of Sciences, Research and Cultural Affairs, Germany [IGK2018] |
Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Geowissenschaften |
DDC classification: | 5 Naturwissenschaften und Mathematik / 55 Geowissenschaften, Geologie / 550 Geowissenschaften |
Peer review: | Referiert |