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首页> 外文期刊>Geosphere >Constraints on rock uplift in the eastern Transverse Ranges and northern Peninsular Ranges and implications for kinematics of the San Andreas fault in the Coachella Valley, California, USA
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Constraints on rock uplift in the eastern Transverse Ranges and northern Peninsular Ranges and implications for kinematics of the San Andreas fault in the Coachella Valley, California, USA

机译：东部横向范围和北半岛的岩石隆起的限制以及美国加利福尼亚州Coachella Valley的San Andreas故障的动力学的影响以及美国

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The nexus of plate-boundary deformation at the northern end of the Coachella Valley in southern California (USA) is complex on multiple levels, including rupture dynamics, slip transfer, and three-dimensional strain partitioning on nonvertical faults (including the San Andreas fault). We quantify uplift of mountain blocks in this region using geomorphology and low-temperature thermochronometry to constrain the role of long-term vertical deformation in this tectonic system. New apatite (U-Th)/He (AHe) ages confirm that the rugged San Jacinto Mountains (SJM) do not exhibit a record of rapid Neogene exhumation. In contrast, in the Little San Bernardino Mountains (LSBM), rapid exhumation over the past 5 m.y. is apparent beneath a tilted AHe partial retention zone, based on new and previously published data. Both ranges tilt away from the Coachella Valley and have experienced minimal denudation from their upper surface, based on preservation of weathered granitic erosion surfaces. We interpret rapid exhumation at 5 Ma and the gentle tilt of the erosion surface and AHe isochrons in the LSBM to have resulted from rift shoulder uplift associated with extension prior to onset of transpression in the Coachella Valley. We hypothesize that the SJM have experienced similar rift shoulder uplift, but an additional mechanism must be called upon to explain the pinnacle-like form, rugged escarpment, and topographic disequilibrium of the northernmost SJM massif. We propose that this form stems from erosional resistance of the Peninsular Ranges batholith relative to more-erodible foliated metamorphic rocks that wrap around it. Our interpretations suggest that neither the LSBM nor SJM have been significantly uplifted under the present transpressive configuration of the San Andreas fault system, but instead represent relict highs due to previous tectonic and erosional forcing.
机译：南加州南部（美国）北端的板边界变形的底漆在多个水平上复杂，包括破裂动力学，滑动转移和在非矫形断层上的三维应变分区（包括SAN Andreas Fault） 。我们使用地貌和低温热化学测量该地区的隆起的隆起，以限制该构造系统中长期垂直变形的作用。新磷灰石（U-TH）/他（AHE）年龄确认崎岖的San Jacinto Mountains（SJM）没有表现出快速的Neogene挖掘的记录。相比之下，在小圣贝纳迪诺山脉（LSBM），过去5米的快速挖掘。基于新的和以前公布的数据，在倾斜的AHE部分保留区下方是显而易见的。两种范围都倾向于远离Coachella山谷，并根据风化的花岗岩腐蚀表面的保存，从其上表面倾斜的显着剥落。我们将5 mA的快速挖掘和LSBM中的侵蚀表面的温和倾斜和AHE等荷倾斜，从裂缝叶片发作之前与延伸相关联的裂缝肩部隆起。我们假设SJM经历了类似的裂缝肩隆起，但必须要求额外的机制解释最北端的SJM Massif的顶峰状形式，粗糙的悬崖和地形不平衡。我们提出这种形式源于半岛范围的侵蚀性，相对于缠绕在其周围的更易于易于卵形的叶状岩石。我们的解释表明，在San Andreas故障系统的当前变压配置下，LSBM和SJM都没有显着提升，而是由于先前的构造和侵蚀强迫，因此表示依赖高位。

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