Quantifying canyon incision and Andean Plateau surface uplift, southwest Peru: A thermochronometer and numerical modeling approach
Quantifying canyon incision and Andean Plateau surface uplift, southwest Peru: A thermochronometer and numerical modeling approach
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量化秘鲁西南部的峡谷切口和安第斯高原表面隆起：温度计和数值模拟方法
DOI：
10.1029/2009jf001305
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发表时间：
2009
影响因子：
--
通讯作者：
K. Hodges
中科院分区：
文献类型：
--
作者：
T. Schildgen;T. Ehlers;D. Whipp;M. V. Soest;K. Whipple;K. Hodges
切口我们量化的时间和规模的切口整合以前公布的年龄从谷底19个新的样本年龄从四个谷壁断面。由于俯冲和火山作用，地壳底部的温度从西南到东北升高，从冷却时代解释切割历史变得复杂。此外，大幅度的切口导致额外的三维变化的热场。我们解决这些并发症与有限元热和thermochronometer年龄预测模型，以量化的地形演变的情况下观察到的冷却年龄一致的范围。将275个模型模拟结果与观测到的冷却年龄和区域热流测定结果进行比较，确定了最佳拟合历史，在-14 Ma之前弧前区域有-0.2 km的切口，在7 - 11 Ma之间开始有3.0 km的切口。从7 Ma开始的切口需要在-5.5至6 Ma结束。然而，2.2马年龄的火山流在目前的谷底和5马砾石隆起的皮埃蒙特表面一起表明，切口结束在2.2和5马之间的时间跨度。切口结束时间的这些附加约束导致最佳拟合切口开始时间范围在8 Ma和11 Ma之间，其必须与地表隆起一致或晚于地表隆起。
incision. We quantify the timing and magnitude of incision by integrating previously published ages from the valley bottom with 19 new sample ages from four valley wall transects. Interpretation of the incision history from cooling ages is complicated by a southwest to northeast increase in temperatures at the base of the crust due to subduction and volcanism. Furthermore, the large magnitude of incision leads to additional threedimensional variations in the thermal field. We address these complications with finite element thermal and thermochronometer age prediction models to quantify the range of topographic evolution scenarios consistent with observed cooling ages. Comparison of 275 model simulations to observed cooling ages and regional heat flow determinations identify a best fit history with � 0.2 km of incision in the forearc region prior to � 14 Ma and up to 3.0 km of incision starting between 7 and 11 Ma. Incision starting at 7 Ma requires incision to end by � 5.5 to 6 Ma. However, a 2.2 Ma age on a volcanic flow on the current valley floor and 5 Ma gravels on the uplifted piedmont surface together suggest that incision ended during the time span between 2.2 and 5 Ma. These additional constraints for incision end time lead to a range of best fit incision onset times between 8 and 11 Ma, which must coincide with or postdate surface uplift.