The geological history of northwestern South America: from Pangaea to the early collision of the Caribbean Large Igneous Province (290–75Ma)
The geological history of northwestern South America: from Pangaea to the early collision of the Caribbean Large Igneous Province (290–75Ma)
复制标题
南美洲西北部的地质历史：从盘古大陆到加勒比大型火成岩省的早期碰撞（290-75Ma）
DOI：
10.1016/j.gr.2014.06.004
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发表时间：
2015
影响因子：
6.1
通讯作者：
Bernado Beate
中科院分区：
文献类型：
--
作者：
R. Spikings;Ryan Cochrane;D. Villagómez;R. Lelij;C. Vallejo;W. Winkler;Bernado Beate
南美洲西北部保存了自晚白垩世以来泛古陆西部的组装、其解体和远西特提斯威尔逊旋回的启动、随后的太平洋边缘岩浆活动和海洋高原-大陆相互作用的记录。许多模型已经提出了各种时间片，虽然它们是基于空间限制的数据集，或日期是不准确的估计时间的结晶。在这里，我们回顾了大量的地质年代学，地球化学，热年代学，沉积学和古地磁数据，共同提供了严格的约束地质模型。这些数据是在平行于海沟（太平洋）的距离大于1500公里（哥伦比亚和厄瓜多尔）上收集的，揭示了裂谷和俯冲的重要时间趋势。我们的模型约束的时间框架得到强大的，一致的锆石U-Pb年龄的岩浆岩在290-75马。40 Ar/39 Ar和裂变径迹数据描述了晚白垩世（< 350 °C）的热历史，磷灰石U-Pb热年代学则制约了更高的温度和更古老的（75 Ma前）历史。Hf（锆石），Nd（全）和O（石英）同位素组成随时间的变化已被用来跟踪岩浆源区的演化，并被用作地壳厚度的替代品。原子化学成分，结合同位素和致密矿物组合被用来区分大陆和海洋环境。这些数据表明，泛古陆西部的裂谷开始于240 Ma，导致海底在216 Ma时在中美洲和南美洲之间扩展。太平洋活动边缘开始于209 Ma，并一直持续到115 Ma以上的东倾俯冲带，该俯冲带正在回滚，削弱了南美洲并形成新的大陆地壳。115 Ma时，南大西洋的打开使南美洲向西移动，挤压了南美洲西北部的太平洋边缘，并形成了一个折返的俯冲带。被动边缘条件占上风，直到海洋高原和其上覆的洋内弧（里约卡拉弧）碰撞和增生到南美洲在75马。
Northwestern South America preserves a record of the assembly of western Pangaea, its disassembly and initiation of the far western Tethys Wilson Cycle, subsequent Pacific margin magmatism and ocean plateau–continent interaction since the Late Cretaceous. Numerous models have been presented for various time slices although they are based on either spatially restricted datasets, or dates that are inaccurate estimates of the time of crystallisation. Here we review a very large quantity of geochronological, geochemical, thermochronological, sedimentological and palaeomagnetic data that collectively provide tight constraints for geological models. These data have been collected over a trench (Pacific)-parallel distance of > 1500 km (Colombia and Ecuador), and reveal important temporal trends in rifting and subduction. The temporal framework for our model constraints are obtained from robust, concordant zircon U-Pb ages of magmatic rocks during 290–75 Ma. The Late Cretaceous thermal history of the margin (< 350 °C) is described by40Ar/39Ar and fission track data, and the higher temperature and thus older (pre-75 Ma) history are constrained by apatite U-Pb thermochronology. Variations in the isotopic compositions of Hf (zircon), Nd (whole) and O (quartz) with time have been used to track the evolution of the source of magmatism, and are used as proxies for crustal thickness. Atomic chemical compositions, combined with isotopes and dense mineral assemblages are used to differentiate between continental and oceanic environments. These data show that rifting within western Pangaea started at 240 Ma, leading to sea floor spreading between blocks of Central and South America by 216 Ma. Pacific active margin commenced at 209 Ma, and continued until 115 Ma above an east-dipping subduction zone that was rolling back, attenuating South America and forming new continental crust. The opening of the South Atlantic drove South America westwards, compressed the Pacific margin of northwestern South America at 115 Ma and obducted an exhumed subduction zone. Passive margin conditions prevailed until the Oceanic Plateau and its overlying intra-oceanic arc (The Rio Cala Arc) collided and accreted to South America at 75 Ma.