| 上黑龙江盆地前哨林场黑云母二长花岗岩锆石U-Pb年龄、地球化学特征及地质意义 |
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| 关键词:LA-ICP-MS zircon U-Pb age Hf isotope geochemistry biotite monzonite granite Qianshao forest farm Upper Heilongjiang Basin |
| 基金项目:国家重点研发计划“蒙古-鄂霍茨克洋构造体制成矿系统物质组成与过程”(编号: 2017YFC0601303);贵州省找矿突破战略行动重大协同创新项目“贵州稀土;钡;氟等特色资源成矿规律与找矿预测研究”(编号: [2022]ZD004);贵州省有色金属;核工业地质勘查局科研项目“黔北铝土矿含铝岩系关键金属锂迁移富集机制研究”(编号: GZYSKY2023-1) |
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| Zircon U-Pb Age, Geochemical Characteristics, and Geological Significance of Biotite Monzogranites from Qianshao Forest Farm,Upper Heilongjiang Basin |
| Qianshao forest farm in the Upper Heilongjiang Basin is located on the northern margin of the Erguna micro-block in the eastern part of the Xingmeng orogenic belt. It is separated from the Siberia ancient land by the Mongolia–Okhotsk suture zone in the north. To the east, the Tayuan–Xiguitu fault is adjacent to the Xing’an block. A systematic study of zircon chronology, major and trace elements, and isotopic geochemistry of biotite monzogranites was undertaken on Qianshao forest farm. This provides a theoretical basis for exploring the collision mechanisms between the Erguna micro-block and its adjacent blocks in the Early Paleozoic. Using LA-ICP-MS zircon U-Pb isotope measurement, the crystallization age of the biotite monzogranite in the study area was found to be (458.4±2.4) Ma (MSWD=0.022). The formation age of the rock mass was determined to be the Early Paleozoic and the Middle–Late Ordovician. The zircon Hf isotope ?Hf(t) values range from ?4.64 to 1.84. Most of the zircons are under the chondrite evolution line, and the two-stage model ages (tDM2) range from 715 to 1 126 Ma. Rock mass geochemistry shows that the rock is rich in silicon, aluminum, and alkali. The rare earth partition curve shows a right-sloping characteristic of relative enrichment of light rare earth elements (LREE) and relative depletion of heavy rare earth elements (HREE). The rocks were found to be relatively enriched in large ion lithophile elements, Rb and K, and high field strength elements, Th, U, Zr, and Hf, and relatively depleted in the large ion lithophile elements, Ba, and Sr, and high field strength elements, Nb, Ta, P, and Ti. The identification map of petrogenetic types shows that the biotite monzogranite on Qianshao forest farm has the characteristics of A-type granite. The characteristics of the rock Hf isotope and trace elements have shown that the magma originates from the melting of the ancient crust in the Meso-Neoproterozoic. A few mantle-derived materials are present and melting of newly formed crustal materials has also occurred. The elemental characteristics suggest that the rocks were formed in the extensional tectonic setting after the collision between the Erguna massif and Siberia. Combined with previous studies on the formation background of Early Paleozoic granites in the Erguna Block, the formation mechanisms of Early Paleozoic granites in the northern and northeastern margins of the Erguna Block are believed to be different. The granites from the northern margins were formed under the background of the collision and splicing of the Erguna block with the ancient Siberia and Mongolia–Tuva blocks, whereas the granites from the northeastern margins were predominantly formed under the background of collision and extension of the Erguna and Xing'an blocks. |
| GONG Xin,ZHANG Zhi-bo,DU Lin,CAI Guo-sheng,SONG Xiao-jun,ZENG Fan-xiang,LI Guang-chun,SU Yong-hu,DAN Shi-sheng,ZHAO Yuan-yi.2023.Zircon U-Pb Age, Geochemical Characteristics, and Geological Significance of Biotite Monzogranites from Qianshao Forest Farm,Upper Heilongjiang Basin[J].Acta Geoscientica Sinica,44(6):1017-1035. |
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