Dynamic paleogeography of the Jurassic Andean Basin: pattern of transgression and localisation of main straits through the magmatic arc
Dynamic paleogeography of the Jurassic Andean Basin: pattern of transgression and localisation of main straits through the magmatic arc
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侏罗纪安第斯盆地的动态古地理：通过岩浆弧的海侵模式和主要海峡的定位
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发表时间：
2005
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通讯作者：
J. Vicente
中科院分区：
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作者：
J. Vicente
在全球范围内研究了中安第斯山脉侏罗纪安第斯弧后盆地的古地理演化。本文认为，火山活动弧具有显著的连续性和持续性。直接和间接的沉积学证据都允许确定盆地的西部边界(岛状)和与东部边界(克拉通)相对的位置。重点是与这一岛屿边界相关的火山碎屑沉积和同沉积构造。结果表明，弧型岩浆活动对盆地的沉积物供应有较大贡献。弧形的范围和连续性意味着要找到与古太平洋相连的海峡。海侵时间的系统检查与层序相分析相结合，提供了海侵过程的动态图景。早期海侵的扇区允许区分通过弧形的两个主要航道海湾，从弧形水域同时向北和向南在一个狭窄的弧后沟槽中纵向推进：第一个海湾位于塔塔尔纬度(25°S)，第二个海湾位于库雷普托纬度(35°S)。两者均始于上三叠世，并在赫堂期延伸。独立盆地(塔拉帕卡和阿空加瓜-内乌肯)的演化结束于普连斯巴契亚中期的融合，形成了从丘布特到秘鲁北部的连续拉长盆地。安第斯盆地具有显著的连续性和狭窄性，其构造控制作用毋庸置疑。这是因为它的大地构造背景是一个典型的弧后盆地，毗邻一个非常活跃的岩浆弧，并解释了其岛屿边缘的极端流动性，其特点是巨大的火山碎屑停机坪与相关的泥石流和浊积岩。
The paleogeographic evolution of the Jurassic Andean retroarc basin is examined at a global scale for the Central Andes. In this paper, it is called for the striking continuity and lasting of the active volcanic arc. Both direct and indirect sedimentologic evidences allow to locate the western border (insular) of the basin and opposite it with the eastern border (cratonic). Emphasis is placed on the volcaniclastic deposits and synsedimentary structures associated with this insular border. It is concluded that the arc magmatic activity has contributed considerably in sediment supply to the basin. Extent and continuity of the arc implies to locate the straits connecting with the Paleopacific. Systematic check of the time of transgressions coupled with sequential facies analysis provides a dynamic outlook of the transgressive process. Sectors with early transgression allow to distinguish two main gulfs of passage through the arc from which waters have progressed lengthwise at the same time northward and southward in a narrow retroarc furrow : the first at latitude of Taltal (25°S), the second at latitude of Curepto (35°S). Both initiated in the upper Triassic and extended during the Hettangian. The evolution as separate basins (Tarapaca and Aconcagua-Neuquen) ended by fusion in middle Pliensbachian giving rise to a continuous elongated basin from Chubut to northern Peru. The remarkable continuity and narrowness of the Andean Basin leaves no doubt about its tectonic control. This stems to its geotectonic setting as a typical retroarc basin adjacent to a very active magmatic arc and explains the extreme mobility of its insular margin characterized by a huge volcanoclastic apron with associated debris flows and turbidites.