Garnet granulite facies xenoliths from Yingfengling Cenozoic basalt in Leizhou, Guangdong Province

The granulite xenoliths are first found in Yingfengling pyroclastic rocks of Leizhou region, Guangdong Province. Of them high_pressure garnet granulite xenolith found is very sparse in China. Garnet granulite is different from pyroxene granulite in mineral assemblage and composition. \%P_T\% calculation shows that garnet granulite was formed at 1 130-1 160℃and 1.4-1.7 GPa, and pyriclasite at about 800℃and 0.65-0.80 GPa. High xenolith_derived paleogeotherm indicates Cenozoic rifting in Leizhou area. Granulites with varied mineral assemblages were formed at different depths by the metamorphism of the underplated basaltic melt.     

安徽铜陵白芒山辉石闪长岩体的成因:Sr-Nd-Pb-O同位素制约

白芒山辉石闪长岩体位于安徽铜陵狮子山矿田内,属于高钾钙碱性岩系,形成时代为燕山晚期.运用Sr、Nd、Pb和O同位素综合示踪技术,探讨了该岩体的成因.研究结果表明,白芒山辉石闪长岩锶同位素初始值(ISr)变化于0.707291~0.707315之间;εNd(t)值变化于-13.04~-14.01之间;全岩δ18O值为10.2‰~11.7‰;初始铅同位素组成(t=142.9Ma)为:(206Pb/204Pb)i=17.9790~18.3267,(207Pb/204Pb)i=15.5125~15.6578,(208Pb/204Pb)i=38.1000~38.2117.结合安徽沿江地区岩浆岩研究资料可以看出,白芒山辉石闪长岩体为壳、幔岩浆混合成因,成岩物质起源于扬子下地壳和富集岩石圈地幔的部分熔融,是富集岩石圈地幔和扬子下地壳物质混合的产物,成岩过程后期经历了上地壳物质的混染作用影响.其中富集岩石圈地幔的形成主要与俯冲洋壳与陆壳析出流体的混染与交代作用有关.     

Sr, Nd and Pb isotopic characteristics of granulite and pyroxenite xenoliths from Hannuoba Basalts in five-dimensional space and their geological implications

Sr, Nd and Pb isotopic characteristics of granulite and pyroxenite xenoliths from Han-nuoba Basalts in five-dimensional space are studied. Combined with the distribution of xenoliths, it is suggested that the isotopic relationship between various xenoliths can be well explained by the processes of delamination.