Lower Crustal Composition in the Southwestern United States
Lower Crustal Composition in the Southwestern United States
复制标题
美国西南部的下地壳成分
DOI：
10.1029/2019jb019011
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
McDonough, W. F.
中科院分区：
文献类型：
--
作者：
Sammon, L. G.;Gao, C.;McDonough, W. F.
< jats: title> 摘要< jats: p> 人们对下大陆地壳的组成进行了深入研究，但由于很难对其中大部分进行采样，因此人们对其了解甚少。对大陆地壳最深处部分的岩石学和地球化学分析仅限于对高级变质岩性（例如麻粒岩）的研究。原位下地壳研究需要地球物理实验来确定区域尺度现象。由于剪切波速度 (Vs) 等地球物理特性在不同成分和温度之间并不唯一，因此信息最丰富的下地壳模型结合了地球化学和地球物理知识。我们通过分析美国盆地山脉和科罗拉多高原（该地区拥有丰富的地球化学和地球物理数据）探索了组合建模技术。通过将基于成分和热力学原理的地震速度预测与环境噪声反演进行比较，我们确定了美国西南部的三种成分趋势，反映了三种不同的地质环境。科罗拉多高原（厚地壳）、北部盆地和山脉（中地壳）以及南部盆地和山脉（薄地壳）具有中、中基性和深基性地壳成分。确定下地壳的成分在很大程度上取决于其温度，因为它对岩石矿物学和物理性质有影响。在该区域，我们看到了下地壳总体成分为中镁铁质的证据（53.7< jats: inline-graphic xmlns: xlink=" http://www.w3.org/1999/xlink" xlink: href="graphic/jgrb54052-math-0001.png" xlink: title=" urn: x-wiley: jgrb: media: jgrb54052: jgrb54052-math-0001"/> 7.2 wt.% SiO< jats: inline-graphic xmlns: xlink=" http://www.w3.org/1999/xlink" xlink: href="graphic/jgrb54052-math-0002.png" xlink: title=" urn: x-wiley: jgrb: media: jgrb54052: jgrb54052-math-0002"/>) 并显着显示 SiO< jats: inline-graphic xmlns: xlink=" http://www.w3.org/1999/xlink" xlink: href="graphic/jgrb54052-math-0003.png" xlink: title=" urn: x-wiley: jgrb: media: jgrb54052: jgrb54052-math-0003"/> 具有深度。
< jats: title> Abstract< jats: p> The composition of the lower continental crust is well studied but poorly understood because of the difficulty of sampling large portions of it. Petrological and geochemical analyses of this deepest portion of the continental crust are limited to the study of high‐grade metamorphic lithologies, such as granulite. In situ lower crustal studies require geophysical experiments to determine regional‐scale phenomena. Since geophysical properties, such as shear wave velocity (Vs), are nonunique among different compositions and temperatures, the most informative lower crustal models combine both geochemical and geophysical knowledge. We explored a combined modeling technique by analyzing the Basin and Range and Colorado Plateau of the United States, a region for which plentiful geochemical and geophysical data are available. By comparing seismic velocity predictions based on composition and thermodynamic principles to ambient noise inversions, we identified three compositional trends in the southwestern United States that reflect three different geologic settings. The Colorado Plateau (thick crust), Northern Basin and Range (medium crust), and Southern Basin and Range (thin crust) have intermediate, intermediate‐mafic, and mafic deep crustal compositions. Identifying the composition of the lower crust depends heavily on its temperature because of the effect it has on rock mineralogy and physical properties. In this region, we see evidence for a lower crust that overall is intermediate‐mafic in composition (53.7< jats: inline-graphic xmlns: xlink=" http://www. w3. org/1999/xlink" xlink: href=" graphic/jgrb54052-math-0001. png" xlink: title=" urn: x-wiley: jgrb: media: jgrb54052: jgrb54052-math-0001"/> 7.2 wt.% SiO< jats: inline-graphic xmlns: xlink=" http://www. w3. org/1999/xlink" xlink: href=" graphic/jgrb54052-math-0002. png" xlink: title=" urn: x-wiley: jgrb: media: jgrb54052: jgrb54052-math-0002"/>) and notably displays a gradient of decreasing SiO< jats: inline-graphic xmlns: xlink=" http://www. w3. org/1999/xlink" xlink: href=" graphic/jgrb54052-math-0003. png" xlink: title=" urn: x-wiley: jgrb: media: jgrb54052: jgrb54052-math-0003"/> with depth.
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墨西哥中部圣路易斯波托西下地壳的成分和 SmNd 同位素数据：来自麻粒岩相捕虏体套件的证据
影响因子：
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作者：
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作者：
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影响因子：
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作者：
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阿萨巴斯卡麻粒岩地体和下陆壳动态行为的证据
DOI：
10.1146/annurev-earth-063016-020625
发表时间：
2018
影响因子：
14.9
作者：
Dumond, Gregory;Williams, Michael L.;Regan, Sean P.
通讯作者：
Regan, Sean P.