Collaborative Research: Low Temperature Thermochronology on the San Andreas Fault Observatory at Depth (SAFOD) Pilot Hole

圣安德烈亚斯深部断裂带观测站(SAFOD)先导孔将通过使用两种互补的热年代学方法研究不同深度的岩心样品，为探索断层滑动与地壳热演化之间的关系提供一个极好的机会。Pilot Hole位于加利福尼亚州帕克菲尔德，距离圣安德烈亚斯断层不到两公里，深度将达到2.1公里。该钻孔将在深度不到1公里的地方与萨利安花岗岩相交，类似的花岗岩将在先导孔几公里范围内的地表露出。首席调查员将分析100-200米深度的钻孔岩屑和地表露头的样本。他们将使用磷灰石裂变径迹和U/Th-He热年代学来确定样品的热历史。这项研究将通过使用垂直剖面样品的多个热年代学系统来探索隆起、侵蚀和热流之间的复杂相互作用。这些数据将使PI能够将隆升的影响与地温梯度的变化区分开来，例如圣安德烈亚斯断层产生的长期摩擦热造成的变化。由于Parkfield的隆起历史部分受圣安德烈亚斯断层滑动的控制，他们的工作也将提供有关断层运动学的信息。

0207306Blythe The San Andreas Fault zone Observatory at Depth (SAFOD) Pilot Hole will provide an excellent opportunity for exploring the relationship between fault slip and the thermal evolution of the crust by studying core samples from varying depths using two complementary thermochronologic methods. The Pilot Hole, located in Parkfield, CA less than two kilometers from the San Andreas fault will reach a depth of 2.1 km. The borehole will intersect Salinian granite rocks at a depth of less than 1 km and similar granitic rocks outcrop at the surface within a few kilometers of the Pilot Hole. The Principal Investigators will analyze samples from borehole cuttings at depth intervals of 100 - 200 m and from the surface outcrops. They will determine the thermal history of the samples using apatite fission track and U/Th-He thermochronometers.This study will explore the complex interplay between uplift, erosion, and heat flow by using multiple thermochronologic systems on samples from a vertical profile. These data will allow the PIs to separate the effects of uplift from changes in the geothermal gradient, such as those resulting from the long-term frictional heat generated along the San Andreas fault. Because the uplift history at Parkfield is controlled, in part, by slip along the San Andreas fault, their work will also provide information about the kinematics of the fault.***