Isolating active orogenic wedge deformation in the southern Subandes of Bolivia
Isolating active orogenic wedge deformation in the southern Subandes of Bolivia
复制标题
玻利维亚苏班德斯南部的孤立活动造山楔形变形
DOI：
10.1002/2016jb013145
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
G. Vergani
中科院分区：
文献类型：
--
作者：
J. Weiss;B. Brooks;J. Foster;M. Bevis;A. Echalar;D. Caccamise;J. Heck;E. Kendrick;K. Ahlgren;D. Raleigh;R. Smalley;G. Vergani
一个新的GPS导出的安第斯弧后中部的表面速度场允许评估玻利维亚南部Subandes的造山楔变形，最近的研究表明，大地震（>Mw 8）是可能的。我们发现，弧后并不是与主板块边界地震旋回相隔离的。相反，来自俯冲带地震的信号污染了距离智利海沟800公里以上的速度场。经季节和地震影响校正的两个新的楔横速度剖面揭示了不同的区域，反映了（1）主板块边界在高安第斯山脉上的锁定，（2）造山楔后部的位置和加载速率，以及（3）东翼速度梯度指示Subandes下方的滑脱锁定。对剖面的亚带部分进行建模，结果表明，滑脱锁定宽度（WL）和楔加载速率沿沿着走向存在变化;北方楔滑脱的WL约为100 km，累积滑动速率约为14 mm/年，而南方楔的WL约为61 km，滑动速率约为7 mm/年。当与第四纪地质缩短的估计和全新世内部楔形体变形的证据相比时，新的GPS导出的楔形体加载速率可能表明，南部楔形体正在经历一个通过重新激活先前存在的内部结构而增厚的阶段。相反，我们怀疑北方楔主要通过相对年轻的逆冲断层上的滑动而经历加积或加宽阶段。
A new GPS‐derived surface velocity field for the central Andean backarc permits an assessment of orogenic wedge deformation across the southern Subandes of Bolivia, where recent studies suggest that great earthquakes (>Mw 8) are possible. We find that the backarc is not isolated from the main plate boundary seismic cycle. Rather, signals from subduction zone earthquakes contaminate the velocity field at distances greater than 800 km from the Chile trench. Two new wedge‐crossing velocity profiles, corrected for seasonal and earthquake affects, reveal distinct regions that reflect (1) locking of the main plate boundary across the high Andes, (2) the location of and loading rate at the back of orogenic wedge, and (3) an east flank velocity gradient indicative of décollement locking beneath the Subandes. Modeling of the Subandean portions of the profiles indicates along‐strike variations in the décollement locked width (WL) and wedge loading rate; the northern wedge décollement has a WL of ~100 km while accumulating slip at a rate of ~14 mm/yr, whereas the southern wedge has a WL of ~61 km and a slip rate of ~7 mm/yr. When compared to Quaternary estimates of geologic shortening and evidence for Holocene internal wedge deformation, the new GPS‐derived wedge loading rates may indicate that the southern wedge is experiencing a phase of thickening via reactivation of preexisting internal structures. In contrast, we suspect that the northern wedge is undergoing an accretion or widening phase primarily via slip on relatively young thrust‐front faults.
影响因子：
18.3
作者：
Elliott, J. R.;Jolivet, R.;Stevens, V. L.
通讯作者：
Stevens, V. L.
影响因子：
64.8
作者：
Schurr, Bernd;Asch, Guenter;Vilotte, Jean-Pierre
通讯作者：
Vilotte, Jean-Pierre
影响因子：
3.9
作者：
Lin, Yu-nung Nina;Sladen, Anthony;Socquet, Anne
通讯作者：
Socquet, Anne