Average Pleistocene Climatic Patterns in the Southern Central Andes: Controls on Mountain Glaciation and Paleoclimate Implications
Average Pleistocene Climatic Patterns in the Southern Central Andes: Controls on Mountain Glaciation and Paleoclimate Implications
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安第斯山脉中南部更新世平均气候模式：对山地冰川作用的控制和古气候影响
DOI：
10.1086/338414
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
M. Strecker
中科院分区：
文献类型：
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作者：
K. R. Haselton;G. Hilley;M. Strecker
尽管海拔5000-6800米，现代冰川出现在南部的普纳高原和北部的安第斯山脉中南部的Pampeanas山脉。由于向西降水从450毫米/年减少到不足100毫米/年，现代雪线从阿孔基亚山脉的5100米上升到普纳山脉的5800米。在更新世期间，这些干旱高地经历了多次马槽和山谷冰川作用，可能晚于最后一次间冰期，尽管缺乏年龄控制，无法确定绝对的年代学。在普纳和沿普纳东部边缘的冰川作用产生了一个300米的更新世雪线（PSL）洼地，而在Pampeanas山脉，PSL洼地至少为900米。Pampeanas山脉更大的PSL低压最好的解释是冷却和东风湿度增加的结合，而Puna的PSL低压似乎对湿度增加比温度增加更敏感。以前，该地区的冰川作用被解释为降水增加，太平洋反气旋向北移动和西风带向赤道移动导致雪线向西下降。然而，这些PSL结果需要来自东部而不是来自西部的水分增加。此外，地形数据分析表明，在28°S以北，流域起伏减小。区域景观响应表明，目前观测到的环流模式至少在更新世期间持续存在，也许在过去的几百万年里也持续存在。
Despite elevations of 5000–6800 m, modern glaciers occur along the southern Puna Plateau and the northern Sierras Pampeanas in the southern central Andes. The modern snowline rises from 5100 m in Sierra Aconquija to 5800 m in the Puna as a result of a westward decrease in precipitation from 450 to less than 100 mm/yr. During the Pleistocene these arid highlands experienced multiple cirque and valley glaciation that likely postdate the last interglacial period, although lack of age control prevents an absolute chronology. Glaciation in the Puna and along the eastern Puna edge produced a 300‐m Pleistocene snowline (PSL) depression, while in the Sierras Pampeanas the PSL depression was at least 900 m. The greater PSL depression in the Sierras Pampeanas is best explained by a combination of cooling and increase of easterly moisture, whereas the PSL depression in the Puna appears more sensitive to moisture increases than temperature. Previously, glaciations in this region have been explained by increased precipitation, with a westward depression of the snowline caused by a northward shift of the Pacific anticyclone and equatorward shift of the westerlies. However, these PSL results require an increase of moisture from the east rather than from the west. Further, analysis of topographic data indicates that drainage‐basin relief decreases north of 28°S. The regional landscape response suggests that the circulation patterns currently observed have persisted at least during the Pleistocene and perhaps during the past several million years.