腾冲地块昔马地区早始新世富角闪石镁铁质岩石成因及锆石记录的岩浆演化过程

打开文本图片集

中图分类号：P588.15 DOI：10. 16152/j. cnki. xdxbzr. 2025-03-007

Petrogenesis and magmatic evolution recorded by zircon for Early Eocene hornblende-rich mafic rocks in Xima area， Tengchong Block

ZHAO Shaowei1，YANG Zihao’， FANG Xiaoyu1，WEN Tai1CHEN Jingyuan'，LAI Shaocong²，LI Zuochen'

（1.School of Earth Science and Resources，Chang'an University，Xi'an 71Oo54，China;

2.State Key Laboratory of Continental Evolution and Early Life，Northwest University，Xi'an 71OO69，China）

AbstractThe hornblende-rich mafic rocks exposed in the continental arc is a key objectto research diffrentiation and evolution of arc magmatism in the depth.This paper selected a series of hornblende-rich mafic rocks in Xima area，Tengchong Block to discuss their petrogenesis and evolved process，using the petrography，whole rock major and trace elements，Sr-Nd isotopic compositions，zircon U-Pb dating，Lu-Hf isotopic compositions and trace elements.The age data and isotopic compositions show that the mafic rocks in Xima area are accumulation and diffrentiation products of homogeneous magma in the Early Eocene （51.2＼～52.7 Ma）.The accumulated minerals of gabbro are dominated by clinopyroxene，plagioclase and magnetite；and the plagioclase，clinopyroxene，titanite and apatite are the major of accumulated minerals for hornblende gabbro.The diorite is predominated by crystallzation of crystal-poor evolved melt.The recharge of batch magma resulted in the dissolution and reprecipitation of accumulated minerals during the diffrentiation，such as plagioclase.The morphology，mineral inclusions and trace element of zircons suggest the early crystallization of plagioclase ± orthopyroxene assemblage in the mafic magma could promote the crystallization of zircon in the interaction face between mineral and melt.The wide range of zircon crystallization temperature shows long-time crystallization and the regularvariations of trace elements reflect that zircon crystallized in mafic magma could record crystallization and differentiation processes of mafic magmaefficiently.

Keywordshornblende-rich mafic rocks；accumulate and differentiation； zircon； Tengchong Block

岛弧岩桨作用控制了大陆地壳的增生及垂向分异过程，形成了地球上区别于其他行星的长英质上地壳。（剩余26491字）