摘要
华南腹地存在多个白垩纪的A型花岗岩类或碱性侵入岩,如安徽花山霓辉石钠闪石花岗岩、福建大沅村霓辉石钠铁闪石花岗岩、广东恶鸡脑霞石方钠石正长岩以及浙江大和山辉石石英正长斑岩、苏村晶洞钾长花岗岩。锆石SHRIMP和矿物的40Ar-39Ar年代学研究表明,这些岩石主要形成于137-86Ma。以本文的年代学研究为基础,并结合前人大量研究成果, 将华南晚中生代的A型花岗岩类或碱性侵入岩大致分成三期:(1)侏罗纪(184-152Ma)A型花岗岩类或碱性侵入岩,主要沿“十-杭裂谷带”南段分布,在赣南也有分布,可能与古太平洋板块低速斜向俯冲或平移所导致的走滑伸展或与不受古太平洋板块运动影响的岩石圈伸展有关;(2)早白垩世(139-123Ma)A型花岗岩类或碱性侵入岩,分布于政和-大埔断裂带以西,可能与古太平洋板块快速斜向俯冲所导致的弧后伸展或岩石圈减薄有关;(3)晚白垩世(101-86Ma)A型花岗岩类或碱性侵入岩,主要沿闽浙沿海地区分布,同时在华南腹地也有零星分布,可能与大陆边缘弧的塌陷(collapse)或俯冲洋壳反转(roll- back)后的岩石圈伸展有关。
In the hinterland of South China, there are some Cretaceous A-type granitiods or alkaline intrusive rocks, e. g. , Huashan aegiriteaugite riebeckite granite in Anhui, Dayuancun aegiriteaugite arfvedsonite granite in Fujian, Ejinao nepheline sodalite syenite in Guangdong and Daheshan pyroxene quartz syenite porphyry and Sucun geode-like Kf-granite in Zhejiang. The geochronology of zircon SHRIMP and some minerals （amphibole and K-feldspar） ^40Ar -^39 Ar dating indicates that they were mainly formed in 137 - 86 Ma.Combining with previous published isotopic ages of Late Mesozoic A-type granitiods or alkaline intrusive rocks in South China,our study also suggests that these A-type granitoids alkaline intrusive rocks may be classified as three periods. （l） Jurassic（ 184 - 152Ma） rocks： they distribute along the southern segment of the Shi-Hang rift zone＇ and in the south of Jiangxi, and their petrogenesis was possibly related to the strike-slip and extension due to low-speed and oblique subducting or transcurrent moving of paleo-Pacific plate or lithospheric extension which was independent of the movement of paleo-Pacific plate. （2） Early Cretaceous（139 -123Ma） rocks： they distribute to the west of Zhenghe-Dapu fault zone and the lithospheric thinning or back-arc extension in relation to fast-speed and oblique subducting of paleo-Pacific plate is a likely responsible mechanism for their formation. （3） Late Cretaceous （101 -86Ma） rocks： they mainly occur along the coastal of Fujian-Zhejiang area but distribute sporadically in the hinterland of South China, and they possibly resulted from the lithospheric extension owing to the collapse of the continental marginal arc or the rull-back of subducting oceanic crust.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2005年第3期795-808,共14页
Acta Petrologica Sinica
基金
本文得到国家自然科学基金项目(40172028
40421303
40425003)中国科学院知识创新项目(KZCX3-SW-122
A15-041107
KZCX2-SW-117)国家重点基础研究发展规划项目(No.2002CB412601)的资助
关键词
A型花岗岩
碱性侵入岩
伸展
年代学
中生代
俯冲
古太平洋板块
华南
A-type granitoid, Alkaline intrusive rocks, Extension, Geochronology, Mesozoic, Subduction, Paleo-Pacific plate, South China
