CCSD主孔微破裂脉次生包裹体的均一温度  

Homogenization temperature of Secondary inclusions in microfracture veins of the CCSD main hole.

作　　者：崔军文[1] 唐哲民[1] 

机构地区：[1]中国地质科学院地质研究所,北京10037

出　　处：《岩石学报》2007年第12期3295-3301,共7页Acta Petrologica Sinica

基　　金：国家重点基础研究发展规划(973)项目(2003CB716504);国家自然科学基金重大项目(40399141);中国地质调查局地质大调查项目(编号121201056606);国土资源部大陆动力学重点实验室的联合资助

摘　　要：CCSD主孔中发育有十分丰富的脆性变形现象,按其充填特征大致可划分有石英和方解石充填的微破裂、有矿物薄膜的微破裂和既无矿物充填、又无矿物簿膜的微破裂等3大类。石英微破裂脉和方解石微破裂脉次生包裹体的均一温度分别为110℃～215℃和90℃～190℃,表明前者的形成要早于后者,按现代地热梯度23.4℃/km算,两者的形成深度分别为4.7～9.2km和3.8～8.1 km,9.2km大致可作为宏观上岩石圈发生脆性变形的最大深度或岩石圈由韧性变形域向脆性变形域过渡的界线.片麻岩、榴辉岩和超基性岩微破裂脉的次生包裹体均一温度显示三者由韧性变形域向脆性变形域过渡的深度是不一致的,依次为9.2km、8.5km和8.1km,反映主孔主要岩石类型的脆性变形行为存在有一定差异.根据微破裂的充填物特征和相互切割关系,大致可确定主孔中脆性破裂的形成深度和先后关系:石英微破裂脉,形成最早,深度为4.7～9.2km,方解石微破裂脉的形成深度为3.8～8.1km,8.1 km以上开始出现有矿物薄膜的微破裂,既无矿物充填、又无矿物簿膜的微破裂则是地壳深度3.8km以上的主要脆性变形构造类型.可见,微破裂次生包裹体的均一温度或许可作为宏观上建立CCSD主孔脆性变形构造剖面的重要依据之一。Very abundant brittle deformation phenomena occur in the main hole of the Chinese Continental Scientific Drilling (CCSD) project. According to their filling features, the microfractures may be broadly classified into microfractures filled with quartz and calcite, microfractures with mineral films and microfractures without mineral fillings or mineral films. The homogenization of secondary inclusions in quartz microfracture veins and calcite microfracture veins are 110 degrees C similar to 215 degrees C and 90 degrees C similar to 190 degrees C respectively, indicating that the former formed earlier than the latter. According to the present geothermal gradient of 23.4 degrees C/km, it is estimated that the depths at which the two kinds of veins formed are 4.7 similar to 9.2km and 3.8 similar to 8.1 km respectively. The 9.2km depth may be considered the maximum depth for occurrence of brittle deformation in the lithosphere or the boundary of transition from the ductile to brittle deformation domains. The homogenization temperatures of secondary inclusions in microfracture veins in gneiss, eclogite and ultrabasic rocks show that the depths for the transition from the ductile to brittle deformation domains of the three types of rock are somewhat different, being 9.2, 8.5 and 8.1 km respectively, reflecting that there is some difference in brittle deformation behaviors of the major rock types of the main hole. According to the features of fillings of the microfractures and their crosscutting relationships, the crustal depths and time order of formation of brittle microfractures in the main hole may be largely determined: the quartz microfracture veins formed earlier at 4.7 similar to 9.2km depth, while the calcite microfracture veins formed later at 3.8 similar to 8.1 km; the microfractures with mineral films began to appear at 8.1 km depth; and microfractures without mineral fillings or mineral films are the main type of brittle deformation structure above 3.8km depth. So the homogenization temperatures of secondary

关 键 词：CCSD主孔 脆性变形 次生包裹体 均一温度 矿物(石英、方解石)微破裂脉 变形域 

分 类 号：P588.331[天文地球—岩石学] P593[天文地球—地质学]