科研之友
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摘要
Located in Buqingshan tectonic me´lange belt on the southern margin of Eastern Kunlun Orogeny, Yikehalaer granitoid comprises mainly of grayish white coarse grained granodiorite and fine grained granodiorite with gneissic structure and porphyaceous texture. The zircons of the rock assume typical magmatic zoning structure, suggesting the characteristics of magmatic zircon. The LA-ICP-MS zircon U-Pb age is (436.9±5.7) Ma, suggesting the formation of granitoid in Early Silurian. The authors studied in detail the geological and geochemical characteristics of Yikehalaer granitoid, and the results show that SiO2content ranges from 66.08% to 72.22%, Na2O content ranges from 4.61% to 5.01%, and K2O content ranges from 0.95% to 3.59%, similar to the characteristics of high potassium calc-alkali granite. The trace elements and rare earth elements (RRE) data show that the Yikehalaer granitoid is also classified as a adakitic granite, with high content of Sr ranging from 280×10-6to 493×10-6, low content of Y ranging from 3.76×10-6to 11.7×10-6, low content of Yb ranging from 0.28×10-6to 0.86×10-6, and high content of Sr/Y ranging from 23.93 to 125.0. Moreover, the chondrite-normalized REE patterns show rightly-dipping style, suggesting enrichment of LREE, with no obvious Eu anomaly. Petrogenetic research shows that the granitoid was most probably derived from the partial melting of the 10%~20% garnet amphibolite connecting the subducting oceanic crust. Regional tectonic research shows that the East Kunlun paleo-ocean basin in proto-Tethys domain experienced subduction from Cambrian until Early Silurian, which led to an important oceanic crust melting event at the late stage of oceanic crust subduction in Early Silurian.
- 出版日期2014
- 单位桂林理工大学
