地球学报Issue(4)：473-482,10.DOI:10.3975/cagsb.2015.04.10
东秦岭丹凤地区分水岭蛇绿岩LA-ICP-MS锆石U-Pb年龄、岩石地球化学特征及其构造意义
LA-ICP-MS Zircon U-Pb Dating, Petro-geochemical Characteristics and Geological Significance of Fenshuiling Ophiolite in Danfeng Area of Eastern Qinling Mountains
摘要
Abstract
Ophiolite is one of the key topics in orogenic belt research. In this paper, based on field survey, the authors studied petrology, isotopic age and geochemistry comprehensively, and reached the conclusion that Fenshuiling ophiolite in Danfeng area of Eastern Qinling Mountains is SSZ type ophiolite related to the subduction zone. Metabasalt of ophiolite is a kind of hyalobasalt formed in the fore-arc setting and possesses the following geochemical features in comparison with bonite: its SiO2content is a little lower, MgO (9.24%~18.74%) and Mg#(74~85) values are higher, and TiO2(0.15%~0.38%) values are much lower. Its chondrite-normalized REE patterns are of “U” type, compatible elements Ni, Cr are higher, and HFSE Y, V, Zr, Yb values are relatively lower. The LA-ICP-MS zircon U-Pb age of metagabbro ndicates that Fenshuiling ophiolite was formed at (499.7±6.1) Ma or so. The existence of hyalobasalt suggests that the paleo-Shangdan oceanic crust subducted northwards strongly, and SSZ type ophiolite was formed in the fore-arc setting between the subduction zone and the southern edge of the Northern Qinling block. The results achieved by the authors further complete the understanding of the evolution of the Qinling orogenic belt.关键词
蛇绿岩/玻玄岩/弧前/东秦岭Key words
ophiolite/hyalobasalt/fore-arc/Eastern Qinling Mountains分类
天文与地球科学引用本文复制引用
赵如意,姜常义,李卫红,王江波,汪帮耀,惠争卜..东秦岭丹凤地区分水岭蛇绿岩LA-ICP-MS锆石U-Pb年龄、岩石地球化学特征及其构造意义[J].地球学报,2015,(4):473-482,10.基金项目
本文由中国地质调查局地质调查项目(编号:1212011120567 （）
1212011220375)资助。 （）
