The 87Sr/86Sr Record of Himalayan Paleorivers During the Neogene: Patterns and Causes

新近纪喜马拉雅古河的 87Sr/86Sr 记录：模式和原因

• 批准号: 9725607
• 负责人: Jay Quade
• 金额: $ 33.58万
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-03-01 至 2000-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9725607&HistoricalAwards=false
• 关键词: 87Sr; 86Sr; Record; Himalayan; Paleorivers

9725607 Quade The Himalayas stand at the center of the debate on how mountain building can alter climate. One of the clearest proxies of the global effects of Himalayan uplift is the marine 87Sr/86Sr record. Yet the specific contribution that past and present Himalayan rivers make to the marine 87Sr/86Sr record, and how this contribution translates quantitatively into silicate weathering rates and therefore consumption of atmospheric CO2 is unclear. Our recent research demonstrates that the 87Sr/86Sr ratios of Himalayan paleorivers can be reconstructed from carbonates preserved in the Siwalik Group foreland basin deposits in the frontal part of the Himalayan fold-thrust belt. These data show 87Sr/86Sr ratios have increased markedly in the late Neogene, probably in response to unroofing of high 87Sr/86Sr (0.720-0.729) marble and dolostone in the Lesser Himalayan and frontal Himalayan nappes. We propose to (1) expand our Himalayan river 87Sr/86Sr record into easternmost Nepal, and back to the beginning of the Miocene, thereby completing the isotopic history for the paleo-Ganges river system, (2) quantify the contribution of carbonate versus silicate weathering in a modern Nepali river, and (3) combine the isotopic data with sedimentological, structural, and provenance data from the foreland basin deposits in order to document the entire record of erosional unroofing of the Nepal Himalayas since the beginning of the Miocene. The results of the proposed research will have major implications for our understanding of the relationships between collisional orogenesis, climate, and ocean water chemistry.

9725607 Quade Himalayas站在有关如何改变气候的辩论的中心。 喜马拉雅隆起全球影响最明显的代理之一是Marine 87SR/86SR记录。 然而，过去和现在的喜马拉雅河对海洋87SR/86SR记录做出的具体贡献，以及该贡献如何定量转化为硅酸盐风化速率，因此尚不清楚大气二氧化碳的消耗。 我们最近的研究表明，喜马拉雅古植物的87SR/86SR比率可以从保存在喜马拉雅褶皱折叠式腰部额叶的Siwalik集团前盆地盆地矿床中保存的碳酸盐。 这些数据表明，新近纪晚期的87SR/86SR比显着增加，这可能是为了响应于较小的喜马拉雅山脉和额叶喜马拉雅napp的高度87SR/86SR（0.720-0.729）大理石和多洛斯酮的不盖。 我们建议（1）将我们的喜马拉雅河87SR/86SR的记录扩展到最东部的尼泊尔，然后返回到中新世的开始，从而完成了古河河系统的同位素历史，（2）量化了与现代尼泊尔河中的碳酸盐和硅酸盐在（3）中（3）的构造数据的贡献（3），以及（3）的构造数据（3），以及（3）。前陆盆地的沉积物是为了记录自中新世开始以来尼泊尔喜马拉雅山脉侵蚀性不屋顶的整个记录​​。 拟议研究的结果将对我们对碰撞造山机发生，气候和海洋水化学之间的关系的理解产生重大影响。