Thermotectonic evidence for two-stage extension on the Trinity detachment surface, Eastern Klamath mountains, California
Thermotectonic evidence for two-stage extension on the Trinity detachment surface, Eastern Klamath mountains, California
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加利福尼亚州东克拉马斯山脉 Trinity 分离表面两阶段伸展的热构造证据
DOI：
10.2475/04.2010.02
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发表时间：
2010
影响因子：
2.9
通讯作者：
Jeffrey Bigelow
中科院分区：
文献类型：
--
作者：
G. Batt;S. Cashman;J. Garver;Jeffrey Bigelow
我们提出了综合裂变径迹和（U-Th）/He分析的侦察套件8磷灰石样品沿着一个横断面穿越下盘的Trinity拆离面，一个保存完好的低角度伸展结构在加州的东克拉马斯山脉。当沿着断层暴露残余上明显的延伸线理绘制时，这些热年代学数据显示出显着的变化，并且组合年龄以及观察到的裂变径迹长度变化需要与该结构上的延伸相关的两个离散的剥露事件。一致的白垩纪中期裂变径迹年龄表明，继续早期的滑脱面和/或侵蚀折返的滑动，使上绿片岩相下盘岩石到脆性上地壳域。这一阶段的挖掘工作一直持续到C。80 Ma，终止时，目前暴露的样品仍在地表以下2至3公里处。下盘块体的最后折返发生在始于c的第二个离散事件中。20至23 Ma，与La Grange断层向南延伸的发展或重新激活同时发生。
We present integrated fission-track and (U-Th)/He analysis of a reconnaissance suite of 8 apatite samples along a transect crossing the footwall of the Trinity Detachment Surface, a variably preserved low-angle extensional structure in the Eastern Klamath Mountains of California. These thermochronological data display significant variation when plotted along the extension lineation evident on exposed remnants of the fault, and the combined ages, together with the fission track length variation observed, require two discrete episodes of exhumation associated with extension on this structure. Consistent mid-Cretaceous fission-track ages indicate continuation of earlier slip on the detachment surface and/or erosional exhumation to bring upper greenschist facies footwall rocks into the brittle upper crustal domain. This phase of exhumation continued until c. 80 Ma, terminating while currently exposed samples were still 2 to 3 km below the surface. Final exhumation of the footwall block occurred in a second discrete episode initiating at c. 20 to 23 Ma, contemporaneous with development or re-activation of extension on the La Grange Fault to the south.