冰川作为对山脉形成的破坏性和建设性控制.
Stuart N Thomson1, Mark T Brandon, Jonathan H Tomkin
1Department of Geosciences, University of Arizona, Tucson, Arizona 85271, USA. thomson@email.arizona.edu
Nature
|September 17, 2010
概括
晚凯诺时全球冷却加速了巴塔哥尼亚安第斯山脉的侵蚀,冰川控制了山脉侵蚀速度. 最南端的安第斯山脉显示冰川保护,导致建设性的山脉生长.
科学领域:
- 地质地质地质地质地质地
- 地质形态学 地质形态学
- 气候科学 气候科学
背景情况:
- 理论模型表明,全球变冷和侵蚀增强影响了山脉形成的动态.
- 阿尔卑斯山冰川侵蚀预计将大大减少冰原的宽度和高度.
- 对气候变冷的构造反应的实地证据很少.
研究的目的:
- 为了研究晚期纪气候降温对巴塔哥尼亚安第斯山脉的影响.
- 收集对气候驱动的侵蚀构造反应的现场证据.
- 了解冰川,侵蚀和山脉形成之间的关系.
主要方法:
- 在巴塔哥尼亚安第斯山脉 (38°S至56°S) 收集低温热年代学数据.
- 对冷却年龄的分析,以重建侵蚀历史.
- 侵蚀模式与冰川历史和构造活动的相关性.
主要成果:
- 侵蚀速度的显著增加发生在700万到500万年前,与巴塔哥尼亚冰川相吻合.
- 风向侧面在冰川平衡线高度上观察到的侵蚀率最高.
- 在更高的度 (49°S-56°S) 观察到侵蚀减少和基高度增加.
结论:
- 巴塔哥尼亚安第斯山脉提供了气候驱动的侵蚀影响山脉形成的第一个现场证据.
- 冰川侵蚀速度与冰川平衡线高度和冰的滑动速度密切相关.
- 在最南端的安第斯山脉地区的区域冰川保护导致了建设性增长,与其他地方的侵蚀性减少形成鲜明对比.
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