Uplift of the western Altiplano plateau: Evidence from the Precordillera between 20° and 21°S (northern Chile)
Uplift of the western Altiplano plateau: Evidence from the Precordillera between 20° and 21°S (northern Chile)
复制标题
阿尔蒂普拉诺高原西部的隆起：来自南纬 20° 至 21° 之间的 Precordillera 的证据（智利北部）
DOI：
10.1029/2003tc001519
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发表时间：
2004
期刊：
影响因子：
4.2
通讯作者：
J. Glodny
中科院分区：
文献类型：
--
作者：
P. Victor;O. Oncken;J. Glodny
我们提出了一个定量重建的隆起的西翼的高原（中央安第斯山脉），在地球上最大的单斜之一，构造结构，同构造沉积和地球物理数据的分析的基础上。地壳运动发生在一个向西的、缓慢传播的高角度逆断层系统上，这些逆断层合并成一个联合拆离体，斜坡下降到高原边缘以下的中地壳水平。上部斜坡决定了局部褶皱的几何形状，而下部斜坡则控制着大规模的地表倾斜和隆起。在20°S，该断裂系统在17 Ma ~ 10 Ma之间活动，最大缩短速率为0.22mm/yr。它产生了大约2600米的地表隆起，只有3000米的轻微缩短。它的活动在很大程度上与来自中地壳源的大体积熔结凝灰岩的喷发同步。地球物理数据表明，断层系统在寒冷、坚固的弧前地壳和高原地区下方可能富含流体和/或部分熔融区之间的边界处发生了局部变形。地壳熔融和缩短与高原西部边缘隆升之间的系统关系可以沿着沿着大部分高原侧翼追踪，向南变形和岩浆作用的年龄逐步减小，表明高原段的不连续增加。地壳增厚，高达70公里，从向西俯冲在高原的弧后部分均衡补偿构造表面隆起和单斜形成相对于一个稳定的前弧，只与轻微的倾斜反应。
We present a quantitative reconstruction of uplift of the western flank of the Altiplano plateau (central Andes), one of the largest monoclines on the Earth, on the basis of an analysis of tectonic structures, syntectonic deposits, and geophysical data. Uplift occurred on a west vergent, slowly propagating system of high‐angle reverse faults merging into a joint detachment that ramps down to midcrustal levels below the plateau edge. The upper ramps determine local fold geometries while the lower ramp controls large‐scale surface tilting and uplift. At 20°S, this fault system was active between ∼30 Ma and 5–10 Ma, with maximum shortening rates of 0.22 mm/yr between 17 and 10 Ma. It generated some 2600 m of surface uplift with only minor shortening of ∼3000 m. Its activity was largely synchronous to eruption of large‐volume ignimbrites from a midcrustal source. Geophysical data indicate that the fault system localized deformation at the boundary between a cool, strong forearc crust and a presumably fluid‐rich and/or partially molten zone underneath the plateau area. The systematic relation between crustal melting and shortening with uplift at the western plateau margin can be traced along most of the plateau flank, with a stepwise decrease in age of deformation and magmatism toward the south indicating discontinuous addition of plateau segments. Crustal thickening to as much as 70 km from westward underthrusting in the back arc parts of the plateau isostatically compensated the tectonic surface uplift and monocline formation with respect to a stable forearc, which only reacted with minor tilting.