Discovery and analysis of ultra-micro grinding grain texture in slipping lamellae of ductile-brittle zone  

作　　者：GE Heping1, SUN Yan1, LU Xiancai1, ZHU Wenbin1, GUO Jichun1, LIU Deliang2 & Chi-yuen Wang3 1. Department of Earth Sciences, Nanjing University, State Key Laboratory of Mineral Deposit, Nanjing 210093, China 2. Department of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China 3. Department of Geology and Geophysics, University of California, Berkeley, CA 94720, USA 

出　　处：《Science China Earth Sciences》2004年第3期265-271,共7页中国科学（地球科学英文版）

基　　金：This work was supported by the National Natural Science Foundation of China (Grant Nos. 40173001, 40003002 and 40172072) ; the State Key Laboratory of Oil/Gas Reservoir Geology and Exploitation.

摘　　要：Based on the observation of the deep bore cores sampled from the State of Cali-fornia, USA, preferred arranged particulate concentration belts were found in the ultra-slipping lamellae. And the same phenomenon was found again later in the bore cores from the petroleum basin in the Northern Shaanxi Province. It may be the product of the dynamic processes involv-ing tumbling, grinding and compresso-shearing functions, so the spherical particulates with ul-tra-size of nm and mm are called grinding grain. The formation of the grinding grains is related with the ductile-brittle deformation, the lateral pressure of the slipping, and the very low grade of dynamic metamorphism of the rocks. Based on the systematic analysis, it is indicated that some elements like Nb and Ta are enriched in the grinding grains in the granitic rocks because of the chemical differentiation, and that the slipping lamellae bearing grinding grains in mudstone with smear efficiency prove a perfect seal for oil and gas reservoirs. Meanwhile, the paper provides bases for the studies on the fast stick-slip movement and shear paradigm.Based on the observation of the deep bore cores sampled from the State of Cali-fornia, USA, preferred arranged particulate concentration belts were found in the ultra-slipping lamellae. And the same phenomenon was found again later in the bore cores from the petroleum basin in the Northern Shaanxi Province. It may be the product of the dynamic processes involv-ing tumbling, grinding and compresso-shearing functions, so the spherical particulates with ul-tra-size of nm and mm are called grinding grain. The formation of the grinding grains is related with the ductile-brittle deformation, the lateral pressure of the slipping, and the very low grade of dynamic metamorphism of the rocks. Based on the systematic analysis, it is indicated that some elements like Nb and Ta are enriched in the grinding grains in the granitic rocks because of the chemical differentiation, and that the slipping lamellae bearing grinding grains in mudstone with smear efficiency prove a perfect seal for oil and gas reservoirs. Meanwhile, the paper provides bases for the studies on the fast stick-slip movement and shear paradigm.

关 键 词：slipping lamellae  GRINDING GRAIN texture  ductile-brittle deformation  SMEAR efficiency. 

分 类 号：P542.5[天文地球—构造地质学]