西藏冈底斯山中段第四纪火山岩特征及地质意义

为辨别环境动态变化而进行的多期次环境地球化学填图要求降低不同期次数据间的分析误差，为达此目的，本文提出了衡量各实验室分析质量的新的考核标准，包括：一组标准样不同元素分析值与标准值对数偏差的不合格率；一组标准样不同元素分析值与标准值的相关系数所反映的相似性系数；一组标准样各种元素分析值与标准值在虚拟空间上图形分布的相似性。

Zircon LA-ICP-MS U-Pb dating of Bairiqili gabbro pluton in East Kunlun orogenic belt and its geological significance

Located in the middle of East Kunlun, the Bairiqili gabbro pluton consists of olivine gabbro, anorthosite and amphibolite gabbro. LA-ICP-MS zircon U-Pb dating suggests that the main facies hornblende gabbro intruded at 248.9 ± 4.2 Ma, being part of the Early Triassic magmatism during Paleo-Tethys ocean subduction. Based on previous researches, the authors hold that the Mesozoic magma mixing in the East Kunlun orogenic belt started at least in Early Triassic, and that the Bairiqili pluton provides a window for the study of magma mixing at the subduction stage in East Kunlun. Meanwhile, a large number of inherited zircon ages indicate that East Kunlun basement underwent multi-stage and polycyclic tectono-magma event in Precambrian, and the newly-discovered old age of 2109 ~ 2310 Ma may suggest that there existed another magmatic event in Early Proterozoic, whose geological significance deserves further researches.