Abstract The 1.80–1.76 Ga crystalline basement in Colombia as part of the W-Amazonian Craton is composed mainly of gneisses, granitoids and migmatites, affected later by several compressive and extensional events resulting for example in A-type granites, but also mafic intrusions and dikes. Here we present, after a revision of main geological features, research results obtained on the NW-SE trending ilmenite-apatite-rich Cano Viejita gabbro in the SW-Vichada department some 500 km east of Bogota. Petrographic and geochemical data hint to a metaluminous continental alkaline gabbro enriched in K, Ti and P, possibly due to continental crust reworking or magma mixing, as also confirmed by trace elements characteristics in the apatites like HREE enrichment (Ce/Yb)cn 12–13, negative Eu-anomaly, and Y, Th, Sr, Mn ratios. LA-ICP-MS U–Pb apatite geochronology suggests an early Neoproterozoic emplacement age between 975 ± 9 and 1002 ± 21 Ma related with rifting triggered by the Amazonia-Baltica-Laurentia collision during the Rodinia Supercontinent assembly and associated Grenvillian events. These events also caused mafic intrusions in other parts of the craton. Apatite fission track thermochronometry and thermal history modelling on one sample suggest the onset of the final exhumation stage during Jurassic (~180 Ma), which brought the rocks slowly to their current outcrop position.

中文翻译：

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E-Colombia Caño Viejita 辉长岩的磷灰石 LA-ICP-MS U-Pb 和裂变轨迹年代学：NW Amazonian Craton 中 Grenvillian 板内裂谷和侏罗纪剥落的证据

摘要 作为西亚马逊克拉通一部分的哥伦比亚 1.80-1.76 Ga 结晶基底主要由片麻岩、花岗岩和混合岩组成，后来受到几次挤压和拉伸事件的影响，例如产生 A 型花岗岩，但也有镁铁质侵入体和混合岩。堤防。在此，我们介绍了在对主要地质特征进行修正后，在波哥大以东约 500 公里的 SW-Vichada 部门的 NW-SE 走向富含钛铁矿磷灰石的 Cano Viejita 辉长岩上获得的研究结果。岩石学和地球化学数据暗示了富含 K、Ti 和 P 的金属铝质大陆碱性辉长岩，这可能是由于大陆地壳改造或岩浆混合，这也被磷灰石中的微量元素特征证实，如 HREE 富集 (Ce/Yb)cn 12– 13、负Eu-异常，以及Y、Th、Sr、Mn的比值。LA-ICP-MS U-Pb 磷灰石年代学表明，新元古代早期就位年龄介于 975 ± 9 至 1002 ± 21 Ma，与罗迪尼亚超大陆组装期间亚马逊-波罗的海-劳伦大陆碰撞引发的裂谷以及相关的格伦维尔事件有关。这些事件还导致克拉通其他部分的镁铁质侵入。一个样品的磷灰石裂变轨迹热测时法和热历史模型表明侏罗纪（~180 Ma）的最后折返阶段开始，这将岩石缓慢地带到了它们当前的露头位置。这些事件还导致克拉通其他部分的镁铁质侵入。一个样品的磷灰石裂变轨迹热测时法和热历史模型表明侏罗纪（~180 Ma）的最后折返阶段开始，这使岩石缓慢地到达当前的露头位置。这些事件还导致克拉通其他部分的镁铁质侵入。一个样品的磷灰石裂变轨迹热测时法和热历史模型表明侏罗纪（~180 Ma）的最后折返阶段开始，这将岩石缓慢地带到了它们当前的露头位置。