桐柏—大别造山带剪切带阵列经受长期的应变软化、应变局部化和变形分解作用,形成了一系列构造岩,包括糜棱岩、变晶糜棱岩、半塑性糜棱岩和面理化碎裂岩等。糜棱岩普遍具二相糜棱结构或由相连的弱相基质或层分离强相残斑或布丁所形成的I...桐柏—大别造山带剪切带阵列经受长期的应变软化、应变局部化和变形分解作用,形成了一系列构造岩,包括糜棱岩、变晶糜棱岩、半塑性糜棱岩和面理化碎裂岩等。糜棱岩普遍具二相糜棱结构或由相连的弱相基质或层分离强相残斑或布丁所形成的IWL(Interconnected weak matrix or layers)结构。构造岩中显微构造各式各样,并具一定的组合形式和演化规律,反映了不同环境下主导变形机制的多样性及变形机制间转换的规律性。代表性剪切带岩石化学成分变异的研究表明,除流体流动外,体积亏损是造成某些组分,尤其是一些不活动组分,如钛、磷、锆、钒、钇等相对富集的主导因素,并由化学成分的变异和质量平衡计算,求出了该剪切带的体积亏损率以及流体/岩石值。较大的体积亏损和大量渗透体的存在,对剪切带的化学行为和流变行为都有着重要的影响作用。展开更多
Dinggye lies in the middle part of the Himalayan Orogen. A lot of low angle extension detachment faults have been developed in Dinggye area and some of them make up the main body of the South Tibet Detachment System. ...Dinggye lies in the middle part of the Himalayan Orogen. A lot of low angle extension detachment faults have been developed in Dinggye area and some of them make up the main body of the South Tibet Detachment System. On the whole, the extension direction of all the detachment faults is perpendicular to the strike of the Himalayan Orogen. Each detachment fault has its distinct characteristics. Mylonite was extensively developed in the detachment faults and can be divided into a variety of types such as siliceous mylonite, felsic mylonite, granite mylonite, protomylonite, crystallization mylonite and so on. On the basis of our field survey works, these detachment faults can be classified according to their locations into three units listed as follows: (1) In the northern part of the study area, the detachment faults occur on large scale and in orbicular shape, and form the middle layer of the metamorphic core complexes. (2) In the southern part of the study area, the detachment faults occur in linear shape that is parallel to the Himalayan Orogen and has a stable attitude, and have undergone two phases of development. In the first phase, the Rouqiechun Group rocks were formed and make up the hanging wall, while in the second phase the Jiachun Group rocks were formed and make up the hanging wall. (3) In the southeastern part of the study area, the detachment faults strike nearly along southeast direction in a stable way and some of these detachment faults were distorted by the late-formed faults and folds. Furthermore, in the southwestern part of the study area, the ductile shear zones are parallel to the detachment faults.展开更多
Gas shales with a high gas content were drilled in the Lower Cambrian Lujiaping Formation in the northeastern Sichuan Basin,close to the Chengkou Fault in the Dabashan arc-like thrust fold belt.The equivalent vitrinit...Gas shales with a high gas content were drilled in the Lower Cambrian Lujiaping Formation in the northeastern Sichuan Basin,close to the Chengkou Fault in the Dabashan arc-like thrust fold belt.The equivalent vitrinite reflectance values of organic matters are over 4.0%Ro.The pore structures of the shales were investigated based on microscopy,field emission scanning electron microscopy(FESEM)observations,and low temperature N2 adsorption analysis.The study suggests that cleavages,comprising clay minerals mixed up with organic matter and other insoluble residues,were developed in the rock layers.The clay minerals are directionally arranged,displaying a mylonitized texture.Abundant nanometer-size organic matter and clay mineral particles are well mixed in the cleavage domains,which developed the mylonitized pore system that consists of nanometer-size intergranular pore spaces,aggregate pore spaces in clay mineral flakes and pore network.This mylonitized pore system has high specific surface area,high methane adsorption capacity,and high capillary pressure,which collectively contributes to the preservation of shale gas in such a complex tectonic area.The discovery of the mylonitized pore structure in organic-rich shales may reveal a new mechanism of shale gas enrichment in complex tectonic areas with over-mature organic matter in the northeastern part of Sichuan Basin.展开更多
文摘桐柏—大别造山带剪切带阵列经受长期的应变软化、应变局部化和变形分解作用,形成了一系列构造岩,包括糜棱岩、变晶糜棱岩、半塑性糜棱岩和面理化碎裂岩等。糜棱岩普遍具二相糜棱结构或由相连的弱相基质或层分离强相残斑或布丁所形成的IWL(Interconnected weak matrix or layers)结构。构造岩中显微构造各式各样,并具一定的组合形式和演化规律,反映了不同环境下主导变形机制的多样性及变形机制间转换的规律性。代表性剪切带岩石化学成分变异的研究表明,除流体流动外,体积亏损是造成某些组分,尤其是一些不活动组分,如钛、磷、锆、钒、钇等相对富集的主导因素,并由化学成分的变异和质量平衡计算,求出了该剪切带的体积亏损率以及流体/岩石值。较大的体积亏损和大量渗透体的存在,对剪切带的化学行为和流变行为都有着重要的影响作用。
基金supported by China Geological Survev's regional geological survey program(No.200013000145)in the Dinggve area(H45C004003)of the Qinghai-Tibet Plateau on a scale of 1:250 000
文摘Dinggye lies in the middle part of the Himalayan Orogen. A lot of low angle extension detachment faults have been developed in Dinggye area and some of them make up the main body of the South Tibet Detachment System. On the whole, the extension direction of all the detachment faults is perpendicular to the strike of the Himalayan Orogen. Each detachment fault has its distinct characteristics. Mylonite was extensively developed in the detachment faults and can be divided into a variety of types such as siliceous mylonite, felsic mylonite, granite mylonite, protomylonite, crystallization mylonite and so on. On the basis of our field survey works, these detachment faults can be classified according to their locations into three units listed as follows: (1) In the northern part of the study area, the detachment faults occur on large scale and in orbicular shape, and form the middle layer of the metamorphic core complexes. (2) In the southern part of the study area, the detachment faults occur in linear shape that is parallel to the Himalayan Orogen and has a stable attitude, and have undergone two phases of development. In the first phase, the Rouqiechun Group rocks were formed and make up the hanging wall, while in the second phase the Jiachun Group rocks were formed and make up the hanging wall. (3) In the southeastern part of the study area, the detachment faults strike nearly along southeast direction in a stable way and some of these detachment faults were distorted by the late-formed faults and folds. Furthermore, in the southwestern part of the study area, the ductile shear zones are parallel to the detachment faults.
基金supported by the National Science and Technology Major Project of China(Grant No.2011ZX-05018-002)
文摘Gas shales with a high gas content were drilled in the Lower Cambrian Lujiaping Formation in the northeastern Sichuan Basin,close to the Chengkou Fault in the Dabashan arc-like thrust fold belt.The equivalent vitrinite reflectance values of organic matters are over 4.0%Ro.The pore structures of the shales were investigated based on microscopy,field emission scanning electron microscopy(FESEM)observations,and low temperature N2 adsorption analysis.The study suggests that cleavages,comprising clay minerals mixed up with organic matter and other insoluble residues,were developed in the rock layers.The clay minerals are directionally arranged,displaying a mylonitized texture.Abundant nanometer-size organic matter and clay mineral particles are well mixed in the cleavage domains,which developed the mylonitized pore system that consists of nanometer-size intergranular pore spaces,aggregate pore spaces in clay mineral flakes and pore network.This mylonitized pore system has high specific surface area,high methane adsorption capacity,and high capillary pressure,which collectively contributes to the preservation of shale gas in such a complex tectonic area.The discovery of the mylonitized pore structure in organic-rich shales may reveal a new mechanism of shale gas enrichment in complex tectonic areas with over-mature organic matter in the northeastern part of Sichuan Basin.
