论文部分内容阅读
通过对位于西南印度洋脊超慢速扩张脊东段的大洋钻探计划(ODP)ODP735B钻孔上部岩心不同位置、不同岩性的样品进行全岩主、微量元素分析,并结合前人研究成果,对旋回内部及旋回之间的全岩地球化学特征差异进行了探讨,对其成因进行了约束.ODP735B岩心全岩主量元素特征主要受控于分离结晶生成的矿物组合及比例.全岩主量元素之间的协变关系对反映玄武质熔体结晶演化过程中矿物生成及化学成分演化具有一定的指示意义.稀土元素的分析表明,除较明显的正Eu异常外,旋回1、2均表现出明显的LREE分馏,而HREE则未出现明显分馏.微量元素的分析表明,西南印度洋超低速洋脊的旋回1和旋回2中均表现出明显的Nb、Ta负异常和Sr、K正异常,但不能依靠其全岩微量元素Nb、Ta负异常特征对其源区地球化学特征成因和地质意义进行判断.
Through the analysis of the whole rock and trace elements in different lithotypes and samples from the core of ODP735B in the ODP drilling project located in the eastern part of the super-slow expansion ridge of the Southwestern Indian Ocean Ridge, combined with the previous research results, The differences of the geochemical characteristics of the whole rock between the interior and the gyration are discussed and the causes are constrained.The main elements in the whole rock of the ODP735B core are controlled by the mineral assemblages and the ratios of the separation and crystallization.The main elements of the whole rock Has a certain indication to reflect the mineral formation and evolution of chemical composition in the crystallization process of basaltic melt.The analysis of REE shows that except for the more obvious positive Eu anomalies, Obvious LREE fractionation and no obvious fractionation of HREE.The analysis of trace elements shows that Nb and Ta negative anomalies and Sr and K anomalies are obvious in both Cyclone 1 and Cyclone 2 of the ultra-low velocity ocean ridge in the Southwest Indian Ocean It is not possible to judge the genesis and geologic significance of the geochemical characteristics of the source area by relying on the negative anomalies of trace elements Nb and Ta in the whole rock.