科研之友
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摘要
Sanfoshan granite is distributed in the eastern margin of North China Craton. There are no systematic investigations of diagenetic conditions, mineralogical characteristics and detailed emplacement age. In addition, the relationship between mafic microgranular enclaves and the host rocks is not clear, which are key to understand the petrogenesis of Sanfoshan granite. Here we present different mineral thermal-barometers, whole-rock elemental geochemistry and zircon U-Pb geochronology data of Sanfoshan granite in order to place constraints on the rock type, emplacement age and diagenetic conditions. Moreover, many Sr-Nd and zircon Hf-O isotopic compositions of Early Cretaceous intrusions in the Jiaodong Peninsula are also tested and collected. Combined with the new mineral chemistry data, we infer its magmatic source and petrogenesis. Our results show that Sanfoshan granite is approximately solidified at 2. 20kbar by the barometers of Al-in-hornblende and hornblende-biotite. The solidified temperature calculated by the methods of Al-in-hornblende and biotite Ti thermometer varies in range of 730 680 degrees C. LA-ICP-MS U-Pb dating suggests that these rocks intruded at 119. 6 similar to 111. 4Ma. Taking into account geochemical signatures, emplacement age and isotopic data in this area, it indicates that Sanfoshan granite is I type granite. Co-occurrence of the mafic dike and MMEs should also be the products formed in the same period. Locally there may occur magma mixing. Sanfoshan granite belongs to KCG type granite, suggesting further a tectonic setting transition from compressional to extensional. The higher initial Sr isotopic ratio, lower epsilon(Nd) (t) and t(2DM) (2447 similar to 2143 Ma) of these rocks indicate that the main body of magmatic source is the middle-lower crust of South China Block.
- 出版日期2018
- 单位中国地质调查局发展研究中心; 中国地质大学（北京）
