Ice-sheet control of continental erosion in central and southern Chile (36degree-41degree South) over the last 30,000 years
Bulk sediment chemistry from three Chilean continental margin Ocean Drilling Program sites constrainsregional continental erosion over the past 30,000 years. Sediments from thirteen rivers that drain the(mostly igneous) Andes and the (mostly metamorphic) Coast Range, along with existing rock chemist...
| Published in: | Quaternary Science Reviews |
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| Main Authors: | , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Pergamon-Elsevier Science Ltd
2010
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| Subjects: | |
| Online Access: | http://www.sciencedirect.com https://doi.org/10.1016/j.quascirev.2010.06.037 http://ecite.utas.edu.au/67345 |
| Summary: | Bulk sediment chemistry from three Chilean continental margin Ocean Drilling Program sites constrainsregional continental erosion over the past 30,000 years. Sediments from thirteen rivers that drain the(mostly igneous) Andes and the (mostly metamorphic) Coast Range, along with existing rock chemistrydatasets, define terrestrial provenance for the continental margin sediments. Andean river sedimentshave high Mg/Al relative to Coast-Range river sediments. Near 36S, marine sediments have high-Mg/Al(i.e. more Andean) sources during the last glacial period, and lower-Mg/Al (less Andean) sources duringthe Holocene. Near 41S a Ti-rich source, likely from coast-range igneous intrusions, is prevalent duringHolocene time, whereas high-Mg/Al Andean sources are more prevalent during the last glacial period.We infer that there is a dominant ice-sheet control of sediment sources. At 36S, Andean-sourcedsediment decreased as Andean mountain glaciers retreated after w17.6 ka, coincident with local oceanicwarming and southward retreat of the Patagonian Forest and, by inference, westerly winds. At 41SAndean sediment dominance peaks and then rapidly declines at w19 ka, coincident with local oceanicwarming and the earliest deglacial sea-level rise. We hypothesize that this decreased flux of Andeanmaterial in the south is related to rapid retreat of the marine-based portion of the Patagonian Ice Sheet inresponse to global sea-level rise, as the resulting flooding of the southern portion of the Central Valleycreated a sink for Andean sediments in this region. Reversal of the decreasing deglacial Mg/Al trend at41S from 14.5 to 13.0 ka is consistent with a brief re-advance of the Patagonian ice sheet coincident withthe Antarctic Cold Reversal. |
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