Young displacements on the Atacama Fault System, northern Chile from field observations and cosmogenic 21Ne concentrations
Young displacements on the Atacama Fault System, northern Chile from field observations and cosmogenic 21Ne concentrations
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根据实地观测和宇宙成因 21Ne 浓度，智利北部阿塔卡马断层系统的年轻位移
DOI：
10.1029/2005tc001846
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发表时间：
2006
期刊：
影响因子：
4.2
通讯作者：
R. Allmendinger
中科院分区：
文献类型：
--
作者：
Gabriel González L.;T. Dunai;D. Carrizo;R. Allmendinger
我们给出了智利北部阿塔卡马断裂系统(AFS)年轻变形的第一个数值年龄约束。AFS的年轻活动表现为几个影响科迪勒拉(23°30‘-23°42’S)东侧冲积扇沉积的断层陡坎。详细的冲积扇填图揭示了断层运动、侵蚀和冲积扇发育之间的复杂关系。在陡坡形成之前，一群较老的冲积扇变得不活跃。更年轻的冲积扇，直接来自于补给渠道，并根深蒂固地存在于断层陡坎中，帖子确定了陡坎形成的日期。AFS上最年轻的滑动是由横跨陡坎的迎头侵蚀通道记录的，这些通道又被断层垂直移位0.3-0.5m。对老的非活动扇群的四个地点的石英碎屑进行了宇宙成因的~(21)Ne浓度分析，得出的平均年龄为424±151ka，这是该断裂最近活动的上限。结合断层崖的高度，计算出最小垂直滑动速率为0.01 mm/a。因此，AFS上的年轻位移在年龄上是第四纪的，仅限于晚更新世。
We present the first numerical age constraint for young deformation of the Atacama Fault System (AFS) in northern Chile. The young activity of the AFS is expressed by several fault scarps which affects alluvial fan sediments of the eastern side of the Coastal Cordillera (23°30′–23°42′S). Detailed mapping of alluvial fans reveals a complex relationship between fault motion, erosion and alluvial fan development. An older group of alluvial fans became inactive prior to the scarp formation. Younger alluvial fans, arising directly from feeder channels and entrenched in the fault scarps, posts date the scarp formation. The youngest slip on the AFS is recorded by headward eroding channels entrenched across the scarp which are in turn displaced vertically 0.3–0.5 m by the fault. Quartz fragments in four sites on the older inactive fan group were analyzed for cosmogenic 21Ne concentrations yielding an average age of 424 ± 151 ka, the upper limit for the recent activity of the fault. Combined with the height of fault scarp, we calculate a 0.01 mm/yr minimum vertical fault slip rate. Thus young displacement on the AFS is Quaternary in age and confined to the late Pleistocene.