The origin of the San Jorge Gulf Basin in the context of the Mesozoic-Cenozoic evolution of Patagonia
The origin of the San Jorge Gulf Basin in the context of the Mesozoic-Cenozoic evolution of Patagonia
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DOI：
10.1016/j.jsames.2019.102422
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发表时间：
2020
影响因子：
1.8
通讯作者：
A. Folguera;L. F. Paz;S. Iannelli;C. Navarrete;A. Echaurren;G. Gianni;K. Butler;B. Horton
中科院分区：
文献类型：
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作者：
A. Folguera;L. F. Paz;S. Iannelli;C. Navarrete;A. Echaurren;G. Gianni;K. Butler;B. Horton
巴塔哥尼亚中部弧后地区记录了三个收缩阶段（晚三叠世，晚白垩世和中新世）与弧岩浆活动的东向扩展相一致。弧内迁移可能与俯冲板片变浅、弧前区俯冲侵蚀或两者的结合有关。收缩幕之后是板片回滚，产生了一系列伸展沉积中心和岩浆带，横跨巴塔哥尼亚约170-130 Ma，约55-22 Ma和约5 Ma。这些回滚事件通过断裂、地幔上涌和岩浆注入削弱了巴塔哥尼亚地壳，有利于随后收缩幕的开始和传播。εHf和εNd同位素趋势反映了板片后滚和弧后伸展的阶段，更多的年轻轨迹对应于板片后退过程中地幔上涌进入宽的软流圈楔。演化的εHf和εNd同位素轨迹记录了地壳缩短的周期，证明了改造的地幔来源。巴塔哥尼亚的中-新生代伸展盆地，如丘布特盆地、Cañadón Asfalto盆地、Río Mayo-Aysén盆地、Pilcaniyeu和Auca Pan-El Maitén岩浆带/火山盆地以及Traiguén盆地都是在板块回滚期间形成的。与此相反，伸展相关的圣豪尔赫海湾盆地构成了一个东西走向的异常，在白垩纪的一个间隔，当巴塔哥尼亚西部的其他地区经历缩短。在此期间，地壳演化趋势从幼年转向更进化和弧扩展到大陆内部最有可能在一个平板政权。San Jorge海湾盆地与克拉通盆地内的Neocomian伸展构造有关，后来受到与西部俯冲带和向东的南大西洋初期开放有关的挤压应力的影响。
The retroarc region of central Patagonia recorded three contractional stages (Late Triassic, Late Cretaceous, and Miocene) coincident with eastward broadening of arc magmatism. Inboard arc migration may be linked to shallowing of the subducted slab, subduction erosion of forearc regions, or a combination of both. Contractional episodes were followed by slab rollback, producing a series of extensional depocenters and magmatic belts across Patagonia at ~170-130 Ma, ~55-22 Ma and ~5 Ma. These rollback events weakened Patagonian crust through fracturing, mantle upwelling, and magmatic injection, favoring inception and propagation of subsequent contractional episodes. Phases of slab rollback and retroarc extension are reflected in εHf and εNd isotopic trends, with more juvenile trajectories corresponding to mantle upwelling into a broad asthenospheric wedge during slab retreat. Periods of crustal shortening are recorded by evolved εHf and εNd isotopic trajectories, demonstrating modified mantle sources. Mesozoic-Cenozoic extensional basins of Patagonia, such as the Chubut Basin, Cañadón Asfalto Basin, Río Mayo-Aysén Basin, Pilcaniyeu and Auca Pan-El Maitén magmatic belts/volcanogenic basins, and the Traiguén Basin were generated during episodes of slab rollback. In contrast, the extension-related San Jorge Gulf Basin constitutes an east-west-trending anomaly developed in an interval of the Cretaceous when the rest of western Patagonia experienced shortening. During this time, crustal evolution trends shifted from juvenile to more evolved and the arc expanded toward the continental interior most likely under a flat-slab regime. The San Jorge Gulf Basin is linked to Neocomian extensional structures in an intracratonic basin later influenced by compressional stresses linked to subduction zone in the west and incipient opening of the south Atlantic to east.