Terminal Moraines, Outwash Plains, and Lake Terraces in the Vicinity of Lago Cardiel (49°S; Patagonia, Argentina)—Evidence for Miocene Andean Foreland Glaciations
Terminal Moraines, Outwash Plains, and Lake Terraces in the Vicinity of Lago Cardiel (49°S; Patagonia, Argentina)—Evidence for Miocene Andean Foreland Glaciations
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卡迪尔湖 (Lago Cardiel) 附近的终端冰碛、冲积平原和湖台地（南纬 49°；阿根廷巴塔哥尼亚）——中新世安第斯山前陆冰川作用的证据
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发表时间：
2006
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影响因子：
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通讯作者：
G. Wenzens
中科院分区：
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作者：
G. Wenzens
摘要在拉戈卡迪尔地区(南美洲南部，西经72°15‘，S 49°)发现了9次晚中新世冰川推进，该地区到目前为止一直被认为不是冰川。几个测年结果表明，终止于拉戈卡迪尔以东的圣洛伦索山口四次前进的最小年龄为6.4 Ma，终止于该湖南部的圣马丁冰川的三次最古老冰川的最小年龄为6.6 Ma。两次进一步进展的最小年龄为5.4 Ma。11到14英里。部分覆盖巴塔哥尼亚砾石的古老玄武岩熔岩表明了这些进步的最大年龄。圣马丁冰川最古老的两个冰川末端冰川仅被适度切割到巴塔哥尼亚砾石中，表明其年龄为9至10.5 Ma。这些年龄估计对圣洛伦索海峡的两个梅塞塔冰川尤其准确。这些冰川在中新世鼎盛时期约有240公里长，是末次冰川鼎盛时期的四倍。因此，晚中新世冰川的前进需要比更新世冰川持续时间长得多的更冷和/或更潮湿的条件。由于冰川融化，拉戈卡迪尔的面积要大得多，在南美洲南部的这些早期冰川期间，它是一个地区性的集水区。东南部湖泊阶地在现代湖平面以上350米以上的不规则巨石可能归因于最古老的晚中新世冰雹或冲积平原。
Abstract Nine late Miocene glacier advances are identified in the Lago Cardiel region (49°S, 72°15′W in southern South America), a region that until now has been assumed to be unglaciated. Several dating results indicate a minimum age of 6.4 Ma for four advances of the Monte San Lorenzo lobe terminating east of Lago Cardiel and 6.6 Ma for the three oldest glaciations of the San Martín lobe terminating south of this lake. Two further advances have a minimum age of 5.4 Ma. Eleven to 14 m.y. old basaltic lava, which partly covers Patagonian Gravel, indicates the maximum age of these advances. The two oldest terminal moraines of the San Martín glacier are only modestly incised into the Patagonian Gravel suggesting an age of 9 to 10.5 Ma. These age estimates are especially accurate for both meseta glaciations of the San Lorenzo lobe. These glaciers were about 240 km long during their Miocene maximum, which is four times their length during the Last Glacial Maximum. Hence, the late Miocene glacier advances require colder and/or more humid conditions that were considerably longer lasting than the Pleistocene glaciations. Due to glacial meltwater, Lago Cardiel was significantly larger and served as a regional catchment area during these early glaciations in southern South America. The erratic boulders of the southeastern lake terraces at more than 350 m above modern lake level may be attributed to the oldest late Miocene moraine or outwash plain.