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Local high relief at the southern margin of the Andean plateau by 9 Ma: evidence from ignimbritic valley fills and river incision

  • A valley-filling ignimbrite re-exposed through subsequent river incision at the southern margin of the Andean (Puna) plateau preserves pristine geological evidence of pre-late Miocene palaeotopography in the north western Argentine Andes. Our new Ar-40/(39) Ar dating of the Las Papas Ignimbrites yields a plateau age of 9.24 +/- 0.03 Ma, indicating valley-relief and orographic-barrier conditions comparable to the present-day. A later infill of Plio-Pleistocene coarse conglomerates has been linked to wetter conditions, but resulted in no additional net incision of the Las Papas valley, considering that the base of the ignimbrite remains unexposed in the valley bottom. Our observations indicate that at least 550 m of local plateau margin relief (and likely > 2 km) existed by 9 Ma at the southern Puna margin, which likely aided the efficiency of the orographic barrier to rainfall along the eastern and south eastern flanks of the Puna and causes aridity in the plateau interior.

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Author:Carolina Montero-Lopez, Manfred R. StreckerORCiDGND, Taylor F. Schildgen, Fernando Hongn, Silvina Guzman, Bodo BookhagenORCiDGND, Masafumi Sudo
ISSN:0954-4879 (print)
ISSN:1365-3121 (online)
Parent Title (English):Terra nova
Place of publication:Hoboken
Document Type:Article
Year of first Publication:2014
Year of Completion:2014
Release Date:2017/03/27
First Page:454
Last Page:460
Funder:DAAD (Germany)-Ministerio de Educacion (Argentina); DFG [STR373/28-1]; Emmy Noether grant [SCHI1241/1-1]
Organizational units:Mathematisch-Naturwissenschaftliche Fakultät / Institut für Erd- und Umweltwissenschaften
Peer Review:Referiert