Quaternary glaciolacustrine deposits around a Triple Junction site: Paleolakes at the foot of the Northern Patagonian Ice field (Argentina and Chile)

IF 0.9 4区 地球科学 Q3 GEOLOGY
F. Isla, M. Espinosa
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引用次数: 1

Abstract

The area involved by the triple junction between the South American, Nazca and Antarctic plates activity was affected by Quaternary glaciations. Before 12,800 yrs BP an extended ice field occupied the top of the Patagonian Andes, irradiating glaciers towards the east and the west dominantly. Towards the east, the ice melted in piedmont lakes; towards the west, fjords melted into the Pacific Ocean. The Upper-Pleistocene climate amelioration caused the recession of those glaciers. Some piedmont lakes reversed their Atlantic outflow towards to the Pacific Ocean. The glaciers retreat caused the fluvial reactivations along crustal former faults that were located below the ice. The Patagonian ice field became therefore split into present Northern and Southern fields. At the second largest lake of South America, the Buenos Aires-General Carrera Lake, the water level dropped from about 500 m over present mean sea level to 230 m. Several glaciolacustrine deposits from this area are indicating significant variations caused by climatic changes, volcanism and tectonics, differing in spatial and temporal magnitudes. The triple junction activity involved subduction of the Chile Ridge below the continental South American plate, volcanic activity and faulting. During the glacier melting the Baker River captured three eastern-moving glacial systems towards the southwest, towards the Pacific Ocean. This rapid event is thought to occur 12,800 yrs BP. The lowering of these glaciolacustrine systems should be also interpreted in terms of the tectonic activity in the region and considering other processes operating in the lakes and within the watersheds.
三重交汇点周围的第四纪冰川沉积物:巴塔哥尼亚北部冰原脚下的古湖泊(阿根廷和智利)
南美洲、纳斯卡和南极板块活动三重交汇处所涉及的区域受到第四纪冰川作用的影响。在12800年前,一个延伸的冰原占据了巴塔哥尼亚安第斯山脉的顶部,主要向东部和西部照射冰川。向东,山前湖泊的冰融化了;向西,峡湾融化成太平洋。上更新世气候的改善导致了这些冰川的衰退。一些山前湖泊将大西洋的外流转向太平洋。冰川的退缩导致了位于冰下的地壳前断层的河流复活。因此,巴塔哥尼亚冰原分为现在的北部和南部冰原。在南美洲第二大湖布宜诺斯艾利斯将军卡雷拉湖,水位从目前平均海平面以上约500米下降到230米。该地区的几处冰川沉积物表明,气候变化、火山活动和构造造成了显著变化,在空间和时间上各不相同。三重交界活动涉及南美洲大陆板块下方智利山脊的俯冲、火山活动和断层活动。在冰川融化期间,贝克河捕获了三个向西南和太平洋移动的东部冰川系统。这一快速事件被认为发生在12800年BP。还应根据该地区的构造活动以及湖泊和流域内的其他过程来解释这些冰川系统的下降。
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来源期刊
Andean Geology
Andean Geology 地学-地质学
CiteScore
3.90
自引率
0.00%
发文量
17
审稿时长
>12 weeks
期刊介绍: This journal publishes original and review articles on geology and related sciences, in Spanish or English, in three issues a year (January, May and September). Articles or notes on major topics of broad interest in Earth Sciences dealing with the geology of South and Central America and Antarctica, and particularly of the Andes, are welcomed. The journal is interested in publishing thematic sets of papers and accepts articles dealing with systematic Paleontology only if their main focus is the chronostratigraphical, paleoecological and/or paleogeographical importance of the taxa described therein.
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