Magma mixing of the Cuojiaoma batholith in the Yidun Arc: Evidence from mafic microgranular enclaves

作者：Wang Peng; Dong GuoChen^*; Dong MeiLing; Li YongPing; Xu YiMing; Pan YanNing; Chen Wei; Wu ZongChang

来源：Acta Petrologica Sinica, 2017, 33(8): 2535-2547.

• Magma mixing
• Geochronology
• Geochemistry
• Cuojiaoma batholith
• Yidun Arc

In the northern Yidun Arc, Cuojiaoma batholith consists of biotite quartz monzonite granite and granodiorite. Some mafic microgranular enclaves (MMEs) were discovered in the biotite quartz monzonite granite, showing gradual or clear contacts with the hosted rocks. There were poikiloblastic textures of amphiboles and biotites, coexisting minerals and corrosion zone of plagioclases, as the consequence of the magma mixing of biotite quartz monzonite granite and MMEs. The hosted rocks had higher ratios of LREE/HREE (7. 31 similar to 19. 8) than MMEs (2. 88 similar to 3. 14). Zircons from the hosted rocks yielded the U-Pb age of 236 +/- 1. 9Ma which is consist with the age of MME (235 +/- 3. 9Ma) within the error. The Cuojiaoma batholith was originated from the early stage of the westward subduction of the Ganzi-Litang Ocean, a branch of the Paleo-Tethys, during the Early Triassic. The partial melting of the subducted oceanic slabs served as the magmatic source of the MMEs which ascended and resulted in the partial melting of the lower crust which was the magmatic source of the biotite quartz monzonite. Though the MMEs had higher Cu, Zn contents, MMEs had a little impact on the geochemical compositions of the hosted rocks.

• 出版日期2017
• 单位云南省地质调查局; 中国地质大学（北京）