| 项目编号: | 1346360
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| 项目名称: | Climatic and Tectonic Insights from Low-Temperature Thermochronometry Across the Himalayan Rain Shadow, Everest Region, Nepal and Tibet |
| 作者: | Kip Hodges
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| 承担单位: | Arizona State University
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| 批准年: | 2013
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| 开始日期: | 2014-04-01
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| 结束日期: | 2019-03-31
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| 资助金额: | USD245808
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| 资助来源: | US-NSF
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| 项目类别: | Continuing grant
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| 国家: | US
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| 语种: | 英语
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| 特色学科分类: | Geosciences - Earth Sciences
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| 英文关键词: | himalaya
; south tibetan detachment system
; rain shadow
; climate variation
; uranium-thorium
; transhimalayan river
; southern himalayan flank
; mount everest
; regional scale
; tibetan plateau
; rongbuk valley
; low-temperature thermal structure
; southern tibetan plateau
; central nepal
; southern tibet
; himalayan crest
; shallow fault dip angle
; everest region
; new constraint
; regional tectonic
; recorded annual rainfall
; himalayan orogenic wedge
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| 英文摘要: | The physiographic transition from the Gangetic Plains to the Tibetan Plateau corresponds in space to one of our planet's most profound climate transitions. Several popular geodynamic models for the late Cenozoic evolution of the Himalaya feature a strong feedback relationship between precipitation, erosional rock exhumation, and deformation. If valid, these models predict that the extreme precipitation gradient across the Himalaya should be accompanied by variations in denudation rate and deformational patterns. Previous studies along the southern Himalayan flank conducted to verify these predictions have had mixed results, partly because they were done along the valleys of major rivers that cut across the Himalaya. These 'Transhimalayan' river valleys serve as pathways for northern penetration of monsoon storms, such that erosion rates on either side of the range crest may not truly reflect potential effects of the rain shadow. In addition, extreme incision of the Transhimalayan rivers during uplift of the Himalaya may focus exhumation and obscure broader patterns related to climate and regional tectonics. We endeavor to learn more about exhumation patterns across the rain shadow by applying the (Uranium-Thorium)/Helium thermochronometer to rocks collected along a transect that does not follow a Transhimalayan river. Nearly three decades of research in in the Everest region of central Nepal and southern Tibet by several researcher groups has resulted in an unusually good understanding of the basic structural geology of the region, permitting interpretation of the data obtained in appropriate structural context. Our goal is a comprehensive dataset suitable for thermal-kinematic modeling aimed at providing an improved understanding of the coupled influence of precipitation and dynamics of Himalayan orogenic wedge. We are also taking advantage of a portion of the data produced to explore the timing and slip history of the Lhotse and Qomolangma detachments in the Rongbuk Valley north of Mount Everest. These are two of the best studied of all strands of the South Tibetan detachment system, a major tectonic feature in the Himalaya. While the South Tibetan detachment system is known to have been active throughout the Himalaya in Early to Middle Miocene time, the actual age of youngest movement is poorly constrained in most areas, including the Rongbuk Valley. We are providing new constraints on the low-temperature thermal structure of the footwalls of the two detachments here through (Uranium-Thorium)/Helium and fission track work on accessory minerals. Exposures of the detachments in the Rongbuk Valley are unusual: shallow fault dip angles and high relief conspire to provide sampling opportunities over as distance of greater than 35 kilometers in the direction of transport in the immediate footwall of the South Tibetan detachment system.
While much research focuses on the global impacts of climate variations in space and time, some of the greatest frontiers for research are at smaller, regional scales. On those scales, we are addressing questions about how climate variations relate to other natural earth system processes. Of particular interest for this study is how mountain ranges affect local climate and, conversely, how local climate can influence the erosional history of a mountain range. The high mountain ranges of the Himalaya retard the northward track of the South Asian monsoon system, creating two very different landscapes: the heavily forested slopes of the southern Himalayan flank, which receive some of the highest recorded annual rainfall totals on earth, and the high deserts of the southern Tibetan Plateau. Our work is aimed at understanding how far back in time this climatic pattern may have extended and how it might cause variations in erosion rate north and south of the Himalayan crest. The lessons learned here will inform perceptions of the role of regional climate variation in the erosional process both in the United States and abroad. The project is supporting a talented female Ph.D. candidate, thereby contributing to on-going efforts to reduce the gender disparity between male and female doctoral level scientists, a problem that is particularly acute in the physical sciences. In addition, special multimedia displays are being created for public museum exhibitions exploring the science of climate variations in mountainous landscapes. |
| 资源类型: | 项目
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/97130
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| Appears in Collections: | 影响、适应和脆弱性
气候减缓与适应
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| Recommended Citation: | |
Kip Hodges. Climatic and Tectonic Insights from Low-Temperature Thermochronometry Across the Himalayan Rain Shadow, Everest Region, Nepal and Tibet. 2013-01-01.
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