Pliocene and Early Pleistocene glaciation and landscape evolution on the Patagonian Steppe, Santa Cruz province, Argentina

QUATERNARY SCIENCE REVIEWS

卷:227

Article

Clague, John J.¹  Barendregt, Rene W.²  Menounos, Brian^3,4  Roberts, Nicholas J.^1,5  Rabassa, Jorge⁶  Martinez, Oscar⁷  Ercolano, Bettina⁸  Corbella, Hugo⁹  Hemming, Sidney R.^10,11 

[1] Simon Fraser Univ, Dept Earth Sci, Burnaby, BC V5A 1S6, Canada

[2] Univ Lethbridge, Dept Geog, 4401 Univ Dr, Lethbridge, AB T1K 3M4, Canada

[3] Univ Northern British Columbia, Geog Program, 3333 Univ Way, Prince George, BC V2N 4Z9, Canada

[4] Univ Northern British Columbia, Nat Resources & Environm Studies Inst, 3333 Univ Way, Prince George, BC V2N 4Z9, Canada

[5] Mineral Resources Tasmania, Dept State Growth, 30 Gordons Hill Rd,POB 56, Rosny Park, Tas 7018, Australia

[6] CADIC CONICET, Bernardo Houssay 200, RA-9410 Ushuaia, Tierra Del Fueg, Argentina

[7] Univ Nacl Patagonia San Juan Bosco, Fac Ciencias Nat, Sarmiento 849, Esquel, Chubut, Argentina

[8] Univ Nacl Tierra Fuego, Inst Ciencias Ambiente Sustentabilidad & Recursos, Ave Gobernador Gregores & Piloto Lero Rivera, RA-9400 Rio Gallegos, Argentina

[9] Consejo Nacl Invest Cient & Tecn, Museo Argentino Ciencias Nat, Ave Angel Gallardo 490, Buenos Aires, DF, Argentina

[10] Columbia Univ, Earth & Environm Sci, 413 Comer,61 Route 9W,POB 1000, Palisades, NY 10964 USA

[11] Columbia Univ, Lamont Doherty Earth Observ, 413 Comer,61 Route 9W,POB 1000, Palisades, NY 10964 USA

关键词: Glaciation;    Cenozoic;    Landscape evolution;    Geomorphology;    Radiogenic isotopes;    Paleomagnetism;    Patagonia;    Argentina;    South America;   

DOI  :  10.1016/j.quascirev.2019.105992

来源: Elsevier

【 摘 要 】

At least seven late Pliocene tills cap plateaus (mesetas) south of Lago Viedma, just east of the Andes in Argentine Patagonia. Chronologic constraints on the tills are provided by 40Ar/39Ar ages and magnetic polarities on associated basalt flows and sediments. The tills were deposited by piedmont glaciers that reached at least 80 km east of the crest of the Andes and flowed on a low-relief surface sloping gently downward in that direction. The oldest of the tills is about 3.6 Ma old. Glacial deposits dating to the Pliocene-Pleistocene transition are present at least 40 km beyond the east limit of the Pliocene tills at Lago Viedma, and tills of similar age occur at Condor Cliff in the Rio Santa Cruz valley to the southeast. A sequence of at least seven Early Pleistocene (2.1-1.1 Ma) tills is present between basalt flows in the Cerro del Fraile meseta south of Lago Argentino. The glaciers that deposited these Early Pleistocene tills reached far beyond the Marine Isotope Stage 2 limit in the Rio Santa Cruz valley. Based on positions, extents, and ages of the un-deformed, basalt-capped mesetas flanking Lago Viedma, we conclude that the topography in this area was profoundly changed during the Pleistocene - the low to moderate relief Pliocene surface was deeply incised by glaciers that became increasingly confined to, and flowed within, troughs. The valley floors today are up to 1350 m below the late Pliocene surface. (C) 2019 The Authors. Published by Elsevier Ltd.

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