Analyses of thin slices, cathodoluminescence and carbon-oxygen isotope of calcite veins hosted in marine carbonate rocks distributed around Jingshan County in the middle Yangtze region of South China indicated that, two crystal forms including radial calcite and isometric texture calcite could be identified in calcite veins in the Triassic and the cathodoluminescence intensity was different. The Permian and Ordovician fractures were mainly filled with isometric texture calcite veins and the cathodoluminescence intensity was similar with that of the surrounding rocks. The δl3 CPDB value of calcite veins ranged from -6. 76‰ to 4. Ol‰and the δ18 OPDB value ranged from -17. 95‰to -5. 67‰, indicating the marine phreatic environment and the mixing phreatic environment for calcite veins deposition. Calcite veins in the Triassic were sedimentary origin, and part of calcite veins in the Permian and the Ordovician suffered latter diagenetic fluid dissolution. Fluid generated from organic-matter maturation effected the formation of calcite veins in the Permian to some degree.%通过对中扬子京山县城周边露头碳酸盐岩中方解石脉的普通薄片、阴极发光以及碳氧同位索等资料分析,认为该区露头三叠系裂隙中充填放射状和等轴粒状的方解石且阴极发光强度有差异,二叠系和奥陶系裂隙中主要为等轴粒状方解石,阴极发光与围岩相似.方解石脉的δ13CPDB位于-6.76‰～4.01‰之间,δ18OPDB在-17.95‰～-5.67‰之间,基本为海水潜流带一混合水潜流带沉积环境.三叠系方解石脉基本上为沉积碳酸盐岩,二叠系和奥陶系部分方解石脉受后期成岩流体的影响,其中二叠系有饥质成熟产生的流体对该层系方解石脉的形成有一定影响.
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