中国大陆科学钻探工程主孔100～2000m岩心自然伽马测量及其地质意义  

Natural gamma-ray logging in the main hole (100-2000 m) of the Chinese Continental Scientific Drilling Project and its significance

作　　者：陈世忠[1,2,3] 杨经绥[1,2] 张泽明[1,2] 刘福来[1,2] 李天福[1,2] 邱海峻[2] 牛一雄[2] 王文先[2] 徐海军[2,4] 

机构地区：[1]中国地质科学院地质研究所,国土资源部大陆动力学重点实验室 [2]中国大陆科学钻探工程中心现场,江苏东海222300 [3]中国地质调查局南京地质矿产研究所,江苏南京210016 [4]中国地质大学,湖北武汉430074

出　　处：《中国地质》2005年第2期239-248,共10页Geology in China

基　　金：中国大陆科学钻探工程;科技部973项目(2003CB716503);国家自然科学基金重大项目(4399143);博士后基金联合资助。

摘　　要：中国大陆科学钻探工程使用石油大学研制的岩心地面伽马测量仪对主孔2000m岩心进行了连续测量,并记录峰、谷的伽马值及其对应的岩性、构造和矿化等特征。通过系统测量,建立了主孔2000m自然伽马值剖面,发现榴辉岩具有较低的伽马值,并从榴辉岩→角闪岩→花岗片麻岩,伽马值逐渐增大。伽马值与变质岩的岩性具有明显的对应关系。并从放射性元素U、Th和K含量的角度来看岩石中放射性元素的变化规律,探讨这些元素变化的成因,指出变质基(中)性岩原岩反映的岩浆岩成因,不同于变质泥质沉积岩;岩石高Th/U比值与岩石曾经经历了近地表环境有关。主孔深变质岩自然伽马测量的系统研究对主孔岩心深度归位、探讨岩石成因和区域岩石圈热状态和大地构造演化具有重要的作用。The Ground Core Gamma Eye was used to test the natural gamma values of cores (2000 m) in the main hole of the Chinese Continental Scientific Drilling (CCSD) Project. The peak and valley of the gamma curve and their corresponding petrological, structural and mineralization features were recorded. Through systematic logging, a 2000 m long natural gamma value profile was constructed. The gamma value of eclogite is low and gets high progressively from eclogite through amphibolite to granite gneiss. There is a distinct correspondence between the gamma values and the lithology of metamorphic rocks. Concentrations of the radioactive elements K, U and Th for different types of rock are varied. The genesis of metamorphic rocks is discussed in the context of the radioactivity of these elements in rocks. It is proposed that the genesis of rocks reflected by the protoliths of eclogites and meta-basic (-intermediate) rocks different from that of metapelitic sedimentary rocks. These rocks are orthometamorphites and high Th/U ratios of the rocks are related to the action of near-surface weathering or hydrothermal alteration. The systematic measurements of the natural gamma values of high-grade metamorphic rocks in the main hole are helpful to homing the depth and orientation of cores and studying the genesis of rocks, thermal state of the lithosphere and tectonic evolution.

关 键 词：中国大陆科学钻探工程 自然伽马测量 变质岩 Th/U 岩心样品 

分 类 号：P631.8[天文地球—地质矿产勘探]