Validation on Age of Neoproterozoic Intrusions from Northeastern Margin of Indochina Block,
详细信息
- 责任者：Qi Xuexiang (Key Laboratory for Continental Dynamics ; Ministry of Land and Resources ; Institute of Geology ; Chinese Academy of Geological Sciences ; Beijing 100037 ; China) ; Wang Xiuhua
- 刊名：Acta Petrologica Sinica
- 出版年：2010
- 卷期：26(7)
- 关键词：铀—铅计时 ; U-Pb dating ; 角闪辉长岩 ; hornblende gabbro ; 花岗闪长岩 ; granodiorites ; 云南 ; Yunnan Province
- 页码：p.2141-2154
- 图表：7 illus., 2 tables, 49 refs.
- 分类号：0801
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
Yaojiazai complex massif is located at the northeastern margin of Indochina block and lower grade metamorphic belt for southwestern side of Ailaoshan tectonic zone,made up of hornblende-gabbro and granodiorite.The hornblende-gabbro contains abundance hydrous mineral-hornblende and has 70 km2 outcroup,show that intruded in compressed regional tectonic setting.The high-alumina mafic rock（Al2O3≥16%）features,and the fact that distribution of strongly enrichment of large-ion lithophile elements（K,Rb,Ba and Sr）and light rare earth elements,such as La and Ce,relative to those in the primitive mantle,negative anomaly of Nd and Ta in the primitive mantle-normalized trace elemental spider diagram,Mg#（52.14~65.35）are close to the compositions of primitive arc magmas,and all samples plotted in the field of intraoceanic island arc in the diagram of Ta/Yb vs.Th/Yb,show the hornblende-gabbro is related with subduction of slab,and intruded in arc type tectonic setting.The authors’ study show the ocean crust between the two blocks began to subduct in right-about in Neoproterozoic,and amalgated together each other in Late Neoproterozoic,and formed different size arc magmatic rock zones in the western margin of the Yangtz block and the northeastern margin of the Indochina block, respectively.