| 项目编号: | 1344582
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| 项目名称: | The role of hot crust in mountain building: Testing the alpha-beta quartz transition as a crustal geothermometer |
| 作者: | Vera Schulte-Pelkum
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| 承担单位: | University of Colorado at Boulder
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| 批准年: | 2013
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| 开始日期: | 2014-07-01
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| 结束日期: | 2018-06-30
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| 资助金额: | USD84433
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| 资助来源: | US-NSF
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| 项目类别: | Standard 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: | crustal temperature
; temperature
; crust
; quartz
; phase transition
; α-β quartz transition
; crustal behavior
; change
; melting
; hot felsic middle crust
; quartz transition
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| 英文摘要: | Of all physical parameters that control the behavior of the Earth's crust, temperature is arguably the most difficult to determine accurately. At the same time, temperature controls important processes such as melting (generation of magma), the depth at which deformation processes change from brittle (usually accompanied by earthquakes) to ductile (without earthquakes), and phase transitions between minerals that change the density of the crust, making it more likely to lift high terrain (less dense) or sink into the mantle (denser). The ability to determine crustal temperature is therefore important for the prediction of a wide range of crustal behaviors. Quartz makes up a large portion of the Earth's crust and undergoes a change in mineral structure at a known temperature. This change, and therefore the temperature, can be measured by detecting a characteristic pattern in the velocity of seismic waves traversing the material. We use a systematic combination of seismic techniques to pinpoint the quartz transition and determine crustal temperature.
The α- to β-phase transition of quartz occurs in a narrow temperature range that lies between 580 to 800°C for pressures seen from the Earth?s surface to ~40 km depth. The phase transition generates a sharp compressional seismic velocity (Vp) increase with no accompanying shear velocity (Vs) contrast, unlike other mechanisms such as melting and compositional boundaries, which create contrasts in both Vp and Vs. The hypothesis tested in this study is: In orogens with a hot felsic middle crust, an interface can be detected that generates P reflections but no P to S conversions, and the inferred temperature and pressure are consistent with the presence of the α-β quartz transition and the absence of melting. This study uses a systematic set of teleseismic observation techniques (tests for the occurrence of P-S conversions and P-P reflections/conversions from the same discontinuity) in combination with petrophysical modeling to investigate crustal temperature and its geodynamic consequences in the Himalaya-Tibet and Taiwan orogens; if successful, the method can be widely applied to constrain the temperature of orogens worldwide. |
| 资源类型: | 项目
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/96588
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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: | |
Vera Schulte-Pelkum. The role of hot crust in mountain building: Testing the alpha-beta quartz transition as a crustal geothermometer. 2013-01-01.
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