Meso-Neoproterozoic dolostone is abnormally well-developed in the platform areas in China,detailly,in the Mesoproterozoic Calymmian Wumishan Formation of North China Basin,Neoproterozoic Edia-caran Qigbulak Formation of Tarim Basin,and the Neoproterozoic Ediacaran Dengying Formation of Sichuan Basin.The outcrops and drilling cores from these basins show that these dolostones are mostly thick-bedded to massive,with mud-sized to silt-sized crystalline dolostone reaching 86％-97％of the total dolostone thickness.These dolostones basically suffered no secondary metasomatism,regardless of containing microorganisms(such as algae and bacteria)or not.The analyses of sedimentary palaeogeographic features indicate that:(1)the Meso-Neoproterozoic dolostone nearly covered the entire area basins,and was widely deposited in supratidal to intertidal zones,as well as in open platform environments;(2)the dolostone was subdivided according to the crystalline size,with the distribution controlled by geomorphology,i.e.,the pure mud-sized crystalline dolostone developing in depression areas,whereas the grainy mud-sized crystalline dolostone or the mound stromatolitic mud-sized crystalline dolostone developing in uplift areas;(3)deep-water basins developed between the carbonate platforms,and the seismic profiles show that these basins were formed by syngenetic deep faults in the Meso-Neoproterozoic strata.These syngenetic faults increased Mg2+concen-tration in the seawater by injecting rich-Mg2+-bearing hydrothermal fluids into the carbonate platforms.The analyses of geochemical and paleoclimatic indexes reveal that there is no obvious difference in carbon and oxygen isotope ratios between dolostones having different textures,with the ratios similar to those of the global seawater of the Meso-Neoproterozoic,indicating that the silt-sized crystalline dolostone has the same sedimentary origin as the mud-sized crystalline dolostone,i.e.,the former is from authigenic recrystallization of the latter rather than secondary metasomatism.Therefore,whatever the crystalline sizes are,the dolo-stones are all originated from sedimentation.All the petrological,sedimentary and geochemical data suggest that the dolostones covering almost the whole Meso-Neoproterozoic typical platform areas of China are of relatively primary sedimentary origin.

China University of Petroleum(Beijing),Beijing 102249,China;State Key Laboratory of Petroleum Resources and Prospecting,Ministry of Education,Beijing 102249,China;China University of Geosciences(Wuhan),Wuhan 430074,China;PetroChina Research Institute of Petroleum Exploration and Development,Beijing 100083,China

[1]Zhi-Dong Bao;Han-Cheng Ji;Yuan Wang;Zong-Feng Li;Ting Liang;Bo Niu;Ming-Yang Wei;Kai Lu;Yan-Qing Shi;Hua Zhang;Pu Wan;Zhuo-Lun Li;Zhi-Bo Yang;Rui Liu;Can-Xing Liu;Xu-Lin Zhong;Xiao-Qi Guo;Peng-Fei Xiang;Zhong-Xian Cai;Shui-Chang Zhang-.The primary dolostone in the Meso-Neoproterozoic:Cases study on platforms in China)[J].古地理学报（英文版）,2022(02):151-172

Calymmian,Wumishan,Edia,caran,Qigbulak,Dengying,dolostones,palaeogeographic,supratidal,stromatolitic,syngenetic,Mg2+concen

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