Abstract Whole-rock geochemistry and Nd isotopes were used to constrain the nature of the protoliths and provide clues on the metamorphic conditions of the Jambalo blueschists in the Central Cordillera (Colombian Andes). Blueschist-facies rocks and related greenschists belong to a Cretaceous–Paleocene subduction complex. The blueschist occurs as a lens surrounded by greenschist-facies rocks, suggesting that the latter resembles retrograde products of high-pressure rocks. The geochemical composition of blueschists and greenschists indicates similar protoliths, implying that the Jambalo rocks were probably part of a unique and coherent block exposed to different degrees of retrograde metamorphism. Th/La ratios above 0.19 and 143Nd/144Nd compositions of 0.51272 and 0.51259 indicate subduction zone sedimentary input or some crustal contamination, interpreted as the interaction of arc-derived sediments with basalts formed in a supra-subduction zone. The Jambalo schists may represent the youngest exposure of high-pressure metamorphic rocks along the Andes and records of Late Cretaceous Caribbean and South American convergence.

中文翻译：

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哥伦比亚安第斯山脉中央山脉的 Jambaló 蓝片岩和绿片岩原岩及其对晚白垩世加勒比-南美相互作用的构造意义

摘要 全岩地球化学和 Nd 同位素被用来约束原岩的性质，并提供关于中央山脉（哥伦比亚安第斯山脉）Jambalo 蓝片岩变质条件的线索。蓝片岩相岩石和相关的绿片岩属于白垩纪-古新世俯冲杂岩。蓝片岩以被绿片岩相岩石包围的透镜形式出现，表明后者类似于高压岩石的逆行产物。蓝片岩和绿片岩的地球化学成分显示出相似的原岩，这意味着詹巴洛岩可能是一个独特且连贯的块体的一部分，暴露于不同程度的逆行变质作用。Th/La 比值高于 0.19 和 143Nd/144Nd 组成为 0.51272 和 0.51259 表明俯冲带沉积输入或一些地壳污染，解释为弧形沉积物与超俯冲带中形成的玄武岩的相互作用。Jambalo 片岩可能代表了安第斯山脉高压变质岩的最年轻暴露，以及晚白垩世加勒比海和南美辐合的记录。