Spatially heterogeneous post-Caledonian burial and exhumation across the Scottish Highlands
Spatially heterogeneous post-Caledonian burial and exhumation across the Scottish Highlands
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苏格兰高地的空间异质后喀里多尼亚埋葬和挖掘
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发表时间：
2018
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通讯作者：
D. Shuster
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作者：
M. Fame;J. Spotila;L. Owen;J. Dortch;D. Shuster
被动边缘的组装后、后陆缘演化是全球大陆构造的基本要素。被动边缘的热历史和折返历史通常被归因于许多驱动因素，包括裂谷-两侧断崖的抬升和侵蚀撤退、板内断层重新激活、地幔驱动的抬升和侵蚀不平衡，但在许多情况下，特定的因素可能似乎主导了给定的被动边缘的历史。在这里，我们通过量化苏格兰西部的折返模式来研究被动边缘的复杂演化。我们以苏格兰北大西洋被动边缘的热演化为基础，检验了空间非均质因素在驱动造山后埋葬和折返过程中的重要性。利用放射性磷灰石氦计时技术([U-Th]/He；n=14；约31-363 Ma)和热模拟对苏格兰高地西部七个不同野外地点的冷却历史进行了独立调查，证实加里东后的加热和埋藏以及冷却和折返肯定在相对较短的距离(即数十公里)内是可变的。与古近纪热点活动和局部裂谷相关的加热可以解释这种空间差异的部分原因，但其他驱动因素，包括裂谷过程中的边缘倾斜、沿重新活动的断层的垂直分离以及晚新生代不均匀的冰川侵蚀，也可能是产生所观察到的非均质性所必需的。这些结果表明，被动边缘可能经历了不同的埋藏、抬升和侵蚀模式和历史，而没有表现出裂谷之前、裂谷中和裂谷之后行为的单一、主导驱动因素。岩石圈；第10卷；第3期；第406-425页；GSA数据仓库项目2018139|2018年3月23日在线发布https://doi.org/10.1130/L678.1
The postassembly, postrift evolution of passive margins is an essential element of global continental tectonics. Thermal and exhumational histories of passive margins are commonly attributed to a number of drivers, including uplift and erosional retreat of a rift-flank escarpment, intraplate fault reactivation, mantle-driven uplift, and erosional disequilibrium, yet in many cases, a specific factor may appear to dominate the history of a given passive margin. Here, we investigate the complex evolution of passive margins by quantifying exhumation patterns in western Scotland. We build upon the well-studied thermal evolution of the Scottish North Atlantic passive margin to test the importance of spatially heterogeneous factors in driving postorogenic burial and exhumation. Independent investigations of the cooling history from seven different field sites across the western Scottish Highlands using radiogenic apatite helium thermochronometry ([U-Th]/He; n = 14; ca. 31–363 Ma) and thermal modeling confirm that post-Caledonian heating and burial, as well as cooling and exhumation, must have been variable across relatively short distances (i.e., tens of kilometers). Heating associated with Paleogene hotspot activity and rifting locally explains some of this spatial variation, but additional drivers, including margin tilting during rifting, vertical separation along reactivated faults, and nonuniform glacial erosion in the late Cenozoic, are also likely required to produce the observed heterogeneity. These results indicate that passive margins may experience variable burial, uplift, and erosion patterns and histories, without exhibiting a single, dominant driver for behavior before, during, and after rifting. LITHOSPHERE; v. 10; no. 3; p. 406–425; GSA Data Repository Item 2018139 | Published online 23 March 2018 https://doi.org/10.1130/L678.1