摘要
长乐—南澳构造带中发育有晚侏罗世早期、晚侏罗世晚期及早白垩世等3个不同时期的变质变形侵入岩。不同期次侵入岩具有不同的变质变形特征。根据糜棱岩的空间分布、糜棱叶理的切割关系等,表明构造带在中生代发生了3期韧性剪切变形及相关的动力变质作用。第一期为(北西西-南东东向)右行-推覆韧性剪切,具低角闪岩相变质、深部构造层次长石相塑性变形等特征;第二期为(北北西-南南东向)左行-逆冲韧性剪切,具高绿片岩相变质、中深层次长石-石英相塑性变形的特征;第三期为具正断层性质的右行走滑韧-脆性剪切(主剪切面倾向反转为倾向南东),具低绿片岩相变质、中-浅层次石英相韧-脆性变形特征。根据对具有不同变质变形特征的3期侵入岩进行的同位素测年研究所获得7个(组)锆石微区(LA-ICPMS)U-Pb同位素年龄数据,结合地质接触关系等,将3期变质变形时代分别厘定为晚侏罗世早期(149.2Ma~145.4Ma)、晚侏罗世晚期(145.4~137Ma)及早白垩世晚期(100Ma±)。
Metamorphic and deformed granitic rocks in Changle-Nan'ao fault zone was dividied into the early Late Jurassic, late Late Jurassic and Early Cretaceous three periods. Different period's granitic rocks had different characteristics of deformation and metamorphism. According to metamorphism and deformation style, and the foliation crosscutting relation in different period's intrusions, ductile deformation and related dynamic metamorphism in this tectonic zone can he divided into three stages: The first stage's ductile shear zone is characterized by deep structural level plastic deformation and low amphibolite facies metamorphism, dextralthrusting from NWW to SEE; the second stage's ductile shear zone is characterized by the middle-deep structural level ductile shear deformation and high greenschist facies metamorphism, sinistral-thrusting from NNW to SSE; The third stage's ductile-brittle shear zone is characterized by mid-shallow brittle-ductile shear deformation and low greenschist facies metamorphism , normal-dextral strike slip.According to the LA-ICPMS zircon U-Pb isotopic ages and the geologic relations ofthree periods granitic rocks which have different characteristics of deformation and metamorphism, they were proved that the first stage deformation and metamorphism took place at early Late Jurassic (149.2--145.4 Ma), and second's occurred in late Late Jurassic (145.4-- 137 Ma), third's happened in late Early Cretaceous (ca. 100 Ma) .
出处
《福建地质》
2011年第3期189-199,共11页
Geology of Fujian
基金
地质大调查项目(编号1212011085472
1212010813064)
关键词
构造带
变质变形
期次划分
时代厘定
长乐-南澳
Tectonic zone, Deformation and Metamorphic, divide stages, stipulation of the age, Changle-Nan'ao