Sinistral shear during Middle Jurassic emplacement of the Matancilla Plutonic Complex in northern Chile (25.4° S) as evidence of oblique plate convergence during the early Andean orogeny
Sinistral shear during Middle Jurassic emplacement of the Matancilla Plutonic Complex in northern Chile (25.4° S) as evidence of oblique plate convergence during the early Andean orogeny
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智利北部（南25.4°）中侏罗世马坦西拉深成杂岩就位期间的左旋剪切是安第斯造山运动早期斜板块汇聚的证据
DOI：
10.1016/j.jsames.2022.104047
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发表时间：
2022
影响因子：
1.8
通讯作者：
Arancibia, G.
中科院分区：
文献类型：
--
作者：
Mavor, S.P.;Singleton, J.S.;Heuser, G.;Gomila, R.;Seymour, N.M.;Williams, S.;Arancibia, G.
大陆俯冲带中的弧岩浆作用促进了刚性上板块的流变弱化，并可将斜向俯冲的分隔槽平行分量容纳到弧内剪切带中。我们记录了智利塔塔尔附近纬度25.4°S的剪切带，该剪切带与∼169Ma马坦西拉深成杂岩的侵入有关，以评估这一时期的弧内变形和可能的构造板块构造。古生代变质沉积岩的多相褶皱被糜棱岩组构覆盖，这些组构在花岗闪长质马坦奇拉岩体的热晕中分布最广，宽达1.4公里，接触变质红柱岩斑岩与组构发育是同步运动的。变质沉积岩中的糜棱岩被∼130万Ma的花岗闪长岩(锆石U-Pb)和∼133Ma的运动后独居岩(U-Pb)叠加。在侏罗纪马坦西拉花岗闪长岩中，沿侵入接触带普遍存在韧性剪切，而贯穿整个岩体的厘米级离散高应变带与集中的热液蚀变和反应减弱有关。变质沉积岩和岩体内的糜棱面理走向北东向北东，倾角陡峭，伸展线理平均为近水平。运动学指标记录的主要是左旋剪切，尽管一些右旋或对称指标和S和L的组构表明存在同轴应变和展平的成分。马坦西拉剪切带的左行走滑运动学可能表明，中侏罗世的会聚具有局部分割成同生岩浆弧的左倾。中侏罗世菲尼克斯-法拉隆扩张中心位于∼25°S以北的左倾-斜向会聚，对安第斯造山早期的板块重构提供了制约。
Arc magmatism in a continental subduction zone facilitates rheological weakening of the rigid upper plate, and can accommodate the partitioned trench-parallel component of oblique subduction into an intra-arc shear zone. We document a shear zone at latitude 25.4° S near Taltal, Chile that was associated with intrusion of the Matancilla Plutonic Complex at ∼169 Ma to evaluate intra-arc deformation and possible tectonic plate configurations during this time period. Polyphase folding of Paleozoic metasedimentary rocks is overprinted by mylonitic fabrics that are most extensive in a zone up to 1.4 km wide in the thermal aureole of the granodioritic Matancilla pluton, where contact metamorphic andalusite porphyroblasts are synkinematic with fabric development. Mylonite in metasedimentary rocks is overprinted by a ∼130 Ma granodiorite (zircon U–Pb) and by ∼133 Ma postkinematic monazite (U–Pb). Within the Jurassic Matancilla granodiorite, pervasive ductile shear occurs along the intrusive contact while centimeter-scale discrete high-strain zones throughout the pluton are associated with focused hydrothermal alteration and reaction weakening. Mylonitic foliation in the metasedimentary rocks and within the pluton strikes N- to NE and dips steeply, while stretching lineations are subhorizontal on average. Kinematic indicators record dominantly sinistral shear, though some dextral or symmetric indicators and S > L fabrics suggest a component of coaxial strain and flattening. Sinistral strike-slip kinematics in the Matancilla shear zone may indicate that Middle Jurassic convergence had sinistral obliquity that was locally partitioned into the contemporaneous magmatic arc. Sinistral-oblique convergence would require the Phoenix-Farallon spreading center to be north of ∼25° S in the Middle Jurassic, providing a constraint to plate reconstructions during the early Andean orogeny.
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DOI：
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发表时间：
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期刊：
影响因子：
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DOI：
--
发表时间：
2000
期刊：
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通讯作者：
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