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Glacial and periglacial deposits of the Lake of the Clouds cirque, Never Summer Mountains, Colorado.

机译：冰川和冰川周缘的云层的太阳马戏团，从不夏季山，科罗拉多州。

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摘要

Glacial and periglacial deposits within the Lake of the Clouds cirque in the Never Summer Mountains of Colorado record four episodes of late Quaternary climate cooling. Three closely spaced end moraines are located on the valley floor approximately 1.7 km from the cirque headwall. The outer and middle moraines enclose small fens on their upstream sides, while the inner moraine is partly overlapped by a large compound tongue-shaped rock glacier. Several smaller lobate rock glaciers and protalus ramparts are located around the perimeter of the cirque.;Close parallelism of the moraines, as well as similarities in weathering and soil development, indicates that all three moraines are of similar age. A radiocarbon date of 11,595 +/- 35 14C yr BP obtained from basal sediment in a core taken from the fen behind the middle moraine indicates that the moraines are pre-Altithermal in age, but soil development and distance from the valley head point to a post-Pinedale age. The moraines are correlated tentatively with Satanta Peak moraines in the adjacent Front Range, and may have formed during a cold period coeval, at least in part, with the European Younger Dryas event. The lower lobe of the large tongue-shaped rock glacier is likely to be of glacigenic origin and probably formed as ice downwasted during retreat from the inner moraine as a consequence of climate warming.;Maximum warming occurred during the Altithermal. A 23-cm-thick peat layer in the midsection of the same sediment core yielded a radiocarbon date of 6200 +/- 25 14C yr BP, and reflects a period of warmer climate and a rise of treeline before renewed cooling and periglacial activity.;Rock-weathering and lichenometric data collected at eleven stations on the periglacial deposits record three episodes of renewed cooling and periglacial activity in post-Altithermal time. The first of these episodes, an early Neoglacial event, reactivated the upper part of the large, tongue-shaped rock glacier, and produced two lobate rock glaciers higher on the cirque wall. A second episode, correlative with Audubon activity, led to expanded snow cover unaccompanied by rock glacier activity. During a final episode of cooling, coeval with the Arapaho Peak advances in the Front Range, a smaller tongue-shaped rock glacier formed above Lake of the Clouds and remains active today.
机译：科罗拉多州的从不夏季山脉的云湖旋流中的冰川和周缘冰层沉积记录了第四纪晚期第四次气候降温。在谷底上，距离太阳马戏团顶墙约1.7公里，分布着三个密密麻麻的末端壁rain。外部和中间的冰rain在它们的上游侧包围着小，而内部的冰ora被大型的复合舌状岩石冰川部分地覆盖。在太阳马戏团的周围分布着几个较小的叶状岩石冰川和Protalus壁垒。mo鼠的紧密平行性以及风化和土壤发育的相似性表明，这三个all鼠的年龄相似。从冰m中部后面的芬取的岩心中的基础沉积物中获得的放射性碳数据为11,595 +/- 35 14C yr BP，表明该rain鼠的年龄是早Altithermal的，但土壤发育和从谷头到谷点的距离后潘代尔时代。这些毛rain暂时与邻近锋域的Satanta Peak毛rain相关，并且可能是在寒冷时期（至少在某种程度上）与欧洲年轻树妖事件一起形成的。大舌状岩石冰川的下叶很可能是冰川成因的，并且可能是由于气候变暖而从内部冰ora撤退过程中被冰层消融而形成的；最大的变暖发生在高原。 ；在同一沉积物芯的中部，厚23厘米的泥炭层产生了6200 +/- 25 14C yr BP的放射性碳数据，反映了一段较暖的气候时期和树线上升，之后又开始了新的降温和冰缘活动。在冰川后沉积物的11个站点上收集的岩石风化和地衣计量数据记录了在后Altithermal时期发生了3次新的降温和冰川周缘活动。这些事件中的第一个是早期的新冰期事件，重新激活了大的舌形岩石冰川的上部，并在圆规壁的上方产生了两个叶状岩石冰川。与奥杜邦活动有关的第二个事件导致积雪覆盖扩大，而岩石冰川活动却没有。在最后的降温过程中，与阿拉帕霍峰（Arapaho Peak）的同等运动在“前线山脉（Front Range）”中发展，这是一个较小的舌状岩石冰川，形成于云湖之上，至今仍活跃。

著录项

  • 作者

    Straw, Byron M.;

  • 作者单位

    University of Northern Colorado.;

  • 授予单位 University of Northern Colorado.;
  • 学科 Geology.;Geophysics.
  • 学位 M.A.
  • 年度 2010
  • 页码 89 p.
  • 总页数 89
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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