Systematic variation of Late Pleistocene fault scarp height in the Teton Range, Wyoming, USA: Variable fault slip rates or variable landform ages?
Systematic variation of Late Pleistocene fault scarp height in the Teton Range, Wyoming, USA: Variable fault slip rates or variable landform ages?
复制标题
美国怀俄明州提顿山脉晚更新世断层陡坎高度的系统变化：断层滑移速率变化还是地貌年龄变化？
DOI：
10.1130/ges01320.1
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发表时间：
2017
期刊：
影响因子：
2.5
通讯作者：
A. E. Staley
中科院分区：
文献类型：
--
作者：
G. Thackray;A. E. Staley
强烈变化高度的断层崖切割冰川和冲积序列，覆盖蒂顿山脉(美国西部)的断层前缘。陡峭的高度从11.2米到37.6米不等，在地貌较老的地貌上系统地更高。断崖切割冰川表面，从宇宙成因的放射性核素暴露到14.7±1.1ka，平均高度12.0m，平均冰后错动速率为0.82±0.13m/k.y。采用简单陡坡高度(平均11.2m，错动率0.76±0.11m/k.y)。使用垂直分隔)。我们将偏移率应用于较高的断层陡坎，以开发地貌较老地貌的初步年龄估计，初始假设是随着时间的偏移率恒定。16.2±3.9ka到45.9±11.0ka的地貌年龄估计表明，冰川作用和冲积作用在海洋同位素第2阶段和第3阶段影响了山脉前缘。然而，以前的工作表明，断层偏移率的变异性可归因于黄石冰盖的去冰川过程，这表明断层陡坎高度模式也可能被解释为在仅具有微弱对比的地貌中反映了强烈变化的偏移率。这些结果表明，需要对等时地貌和多个时代的沉积物进行详细的地质年代学研究，以了解断裂山脉前缘的断裂作用和冰川作用。
Fault scarps of strongly varying height cut glacial and alluvial sequences mantling the faulted front of the Teton Range (western USA). Scarp heights vary from 11.2 to 37.6 m and are systematically higher on geomorphically older landforms. Fault scarps cutting a deglacial surface, known from cosmogenic radionuclide exposure dating to immediately postdate 14.7 ± 1.1 ka, average 12.0 m in height, and yield an average postglacial offset rate of 0.82 ± 0.13 m/k.y. using simple scarp height (average 11.2 m, offset rate 0.76 ± 0.11 m/k.y. using vertical separation). We apply the offset rate to higher fault scarps to develop preliminary age estimates for the geomorphically older landforms, with an initial assumption of constant offset rate through time. The landform age estimates of 16.2 ± 3.9 ka to 45.9 ± 11.0 ka imply that glaciation and alluviation influenced the range front during marine isotope stages 2 and 3. However, fault offset rate variability, suggested by previous work to be attributable to Yellowstone ice cap deglacial processes, suggests that the fault scarp height pattern might also be interpreted as a reflection of strongly variable offset rates in landforms of only slightly contrasting age. These results demonstrate the need for detailed geochronology of isochronous landforms and sediments of multiple ages, in order to understand both faulting and glaciation on faulted range fronts.