Based on analysis of outcrop,drilling,logging and seismic data,and geotectonic background,the lithofacies paleogeography and paleokarst geomorphology of the Middle Permian Maokou Formation in the northwestern Sichuan ...Based on analysis of outcrop,drilling,logging and seismic data,and geotectonic background,the lithofacies paleogeography and paleokarst geomorphology of the Middle Permian Maokou Formation in the northwestern Sichuan Basin were reconstructed,and the petroleum geological significance of the lithofacies paleogeography and paleokarst geomorphology were discussed.The Maokou Formation is divided into 3 long-term cycles,namely LSCl,LSC2 and LSC3,which correspond to the Member 1,Member 2 and Member 3 of the Maokou Formation,respectively.Controlled by the extensional structure caused by opening of the Mianlue Ocean in the north margin of the upper Yangtze blocks and basement faults produced by mantle plume uplifting,the area had tectonic differentiation in NWW and NE,and sedimentary basement took on episodic settlement from north to south,as a result,the sedimentary systems of Member 1 to Member 3 gradually evolved from carbonate platform to platform-slope-continental shelf.According to the residual thickness,paleokarst geomorphologic units such as karst highland,karst slope and karst depression at different stages were reconstructed.The karst geomorphological units were developed successively on the basis of sedimentary geomorphology.Sedimentary facies and paleokarst geomorphology are of great significance for oil and gas accumulation.The Maokou Formation in northwestern Sichuan has two kinds of most favorable reservoir zone combinations:high energy grain shoal and karst monadnock,platform margin slope and karst slope.Based on this understanding,the planar distribution of the two kinds of reservoir zones were predicted by overlapping the favorable reservoir facies belt with paleokarst geomorphology.The study results provide a new idea and reference for the exploration deployment of the Middle Permian Maokou Formation in the Sichuan Basin.展开更多
Based on isotopic, lithologic and electrical data and logging cycle analysis technique, stratigraphic sequences in the Middle-Upper Cambrian Xixiangchi Group in the Sichuan Basin and its adjacent area are divided, and...Based on isotopic, lithologic and electrical data and logging cycle analysis technique, stratigraphic sequences in the Middle-Upper Cambrian Xixiangchi Group in the Sichuan Basin and its adjacent area are divided, and its sedimentary characteristics and evolution are analyzed. The Xixiangchi Group can be divided into 5 third-order sequences(Sql-Sq5), of which sequences Ⅰ to Ⅲ(Sql-Sq3) are relatively complete, sequences Ⅳ and Ⅴ are denuded in the Late Cambrian because of the Dian-Chuan paleo-uplifts.Third-order sequences of the Xixiangchi Group in this area have the characteristics of thin in the west and thick in the east, showing that the Caledonian paleo-uplift is a synsedimentary paleo-uplift and the paleogeomorphology in the platform is a gentle slope. Sequence Ⅰdevelops high stand systems tract and transgressive systems tract. The other third-order sequences are dominated by highstand systems tracts, and the transgressive systems tracts last shortly in time and are limited in area. The basic features of evaporative-restricted platform of gentle slope type developed continuously in the sedimentary period of the Xixiangchi Group, its sedimentary environment of "high in west and low in east" and the change of micro paleogeomorphology in the platform control the continuous development of sedimentary facies. Open platform is developed only in sequence Ⅰ and sequence Ⅱ, and the inner beach of the platform and the edge beach of the platform are mostly developed in sequence Ⅱ and sequence Ⅲ. It indicates that there are two platform margin zones in the study area,a relatively stable, large-scale platform marginal zone in NE Guizhou-Western Hunan and Hubei, and a moving and small-scale platform marginal zone in North Chongqing-Western Hubei.展开更多
In recent years,the Journal of Palaeogeography(Chinese Edition and English Edition)continually received manuscripts,in which some authors are from China and some are from Pakistan,Lithuania,Morocco,South Africa,etc.Th...In recent years,the Journal of Palaeogeography(Chinese Edition and English Edition)continually received manuscripts,in which some authors are from China and some are from Pakistan,Lithuania,Morocco,South Africa,etc.The authors of these manuscripts,according to the viewpoint and method of Miall’s paper(1985),selected rocks from each bed in the clastic sections of their study areas and induced some rock types,such as conglomerates,sandstones and fine-grained stones,and considered them as lithofacies.It does not conform to the definition of lithofacies.I wrote some papers,i.e.,Feng(2018,2019,2020),to point out the problems and hope that the authors worldwide,especially Chinese authors,will not continually cite,spread and follow Miall’s paper(1985)viewpoint and method blindly.Prof.Miall is the first person who considered rocks(in fact,the sediments)as lithofacies and proposed a facies analysis method.His viewpoint and facies analysis method confused the definition of facies and facies analysis method.My current paper is a special article to discuss the principal problems of Miall’s paper(1985),i.e.,he considered the sediments as lithofacies and utilized lithofacies to analyze facies,but not to discuss the contributions and less strictness of architectural elements of his paper.Here,I have to declare that the facies in my current paper is the facies of sedimentary petrology,but not of other geological disciplines,such as igneous petrology,metamorphic petrology,palaeontology,stratigraphy,geophysics,geochemistry.Certainly,the definitions of facies and lithofacies are controversial.My current paper will adhere to the policy of“A hundred flowers blossom and a hundred schools of thought contend”.I hope that through academic discussions,contends and geological practice,these problems will be solved gradually.展开更多
基金Supported by the National Natural Science Foundation of China (41802147)China Postdoctoral Science(2019M651785)。
文摘Based on analysis of outcrop,drilling,logging and seismic data,and geotectonic background,the lithofacies paleogeography and paleokarst geomorphology of the Middle Permian Maokou Formation in the northwestern Sichuan Basin were reconstructed,and the petroleum geological significance of the lithofacies paleogeography and paleokarst geomorphology were discussed.The Maokou Formation is divided into 3 long-term cycles,namely LSCl,LSC2 and LSC3,which correspond to the Member 1,Member 2 and Member 3 of the Maokou Formation,respectively.Controlled by the extensional structure caused by opening of the Mianlue Ocean in the north margin of the upper Yangtze blocks and basement faults produced by mantle plume uplifting,the area had tectonic differentiation in NWW and NE,and sedimentary basement took on episodic settlement from north to south,as a result,the sedimentary systems of Member 1 to Member 3 gradually evolved from carbonate platform to platform-slope-continental shelf.According to the residual thickness,paleokarst geomorphologic units such as karst highland,karst slope and karst depression at different stages were reconstructed.The karst geomorphological units were developed successively on the basis of sedimentary geomorphology.Sedimentary facies and paleokarst geomorphology are of great significance for oil and gas accumulation.The Maokou Formation in northwestern Sichuan has two kinds of most favorable reservoir zone combinations:high energy grain shoal and karst monadnock,platform margin slope and karst slope.Based on this understanding,the planar distribution of the two kinds of reservoir zones were predicted by overlapping the favorable reservoir facies belt with paleokarst geomorphology.The study results provide a new idea and reference for the exploration deployment of the Middle Permian Maokou Formation in the Sichuan Basin.
基金Supported by the PetroChina Science and Technology Major Project(2016E-0601)
文摘Based on isotopic, lithologic and electrical data and logging cycle analysis technique, stratigraphic sequences in the Middle-Upper Cambrian Xixiangchi Group in the Sichuan Basin and its adjacent area are divided, and its sedimentary characteristics and evolution are analyzed. The Xixiangchi Group can be divided into 5 third-order sequences(Sql-Sq5), of which sequences Ⅰ to Ⅲ(Sql-Sq3) are relatively complete, sequences Ⅳ and Ⅴ are denuded in the Late Cambrian because of the Dian-Chuan paleo-uplifts.Third-order sequences of the Xixiangchi Group in this area have the characteristics of thin in the west and thick in the east, showing that the Caledonian paleo-uplift is a synsedimentary paleo-uplift and the paleogeomorphology in the platform is a gentle slope. Sequence Ⅰdevelops high stand systems tract and transgressive systems tract. The other third-order sequences are dominated by highstand systems tracts, and the transgressive systems tracts last shortly in time and are limited in area. The basic features of evaporative-restricted platform of gentle slope type developed continuously in the sedimentary period of the Xixiangchi Group, its sedimentary environment of "high in west and low in east" and the change of micro paleogeomorphology in the platform control the continuous development of sedimentary facies. Open platform is developed only in sequence Ⅰ and sequence Ⅱ, and the inner beach of the platform and the edge beach of the platform are mostly developed in sequence Ⅱ and sequence Ⅲ. It indicates that there are two platform margin zones in the study area,a relatively stable, large-scale platform marginal zone in NE Guizhou-Western Hunan and Hubei, and a moving and small-scale platform marginal zone in North Chongqing-Western Hubei.
文摘In recent years,the Journal of Palaeogeography(Chinese Edition and English Edition)continually received manuscripts,in which some authors are from China and some are from Pakistan,Lithuania,Morocco,South Africa,etc.The authors of these manuscripts,according to the viewpoint and method of Miall’s paper(1985),selected rocks from each bed in the clastic sections of their study areas and induced some rock types,such as conglomerates,sandstones and fine-grained stones,and considered them as lithofacies.It does not conform to the definition of lithofacies.I wrote some papers,i.e.,Feng(2018,2019,2020),to point out the problems and hope that the authors worldwide,especially Chinese authors,will not continually cite,spread and follow Miall’s paper(1985)viewpoint and method blindly.Prof.Miall is the first person who considered rocks(in fact,the sediments)as lithofacies and proposed a facies analysis method.His viewpoint and facies analysis method confused the definition of facies and facies analysis method.My current paper is a special article to discuss the principal problems of Miall’s paper(1985),i.e.,he considered the sediments as lithofacies and utilized lithofacies to analyze facies,but not to discuss the contributions and less strictness of architectural elements of his paper.Here,I have to declare that the facies in my current paper is the facies of sedimentary petrology,but not of other geological disciplines,such as igneous petrology,metamorphic petrology,palaeontology,stratigraphy,geophysics,geochemistry.Certainly,the definitions of facies and lithofacies are controversial.My current paper will adhere to the policy of“A hundred flowers blossom and a hundred schools of thought contend”.I hope that through academic discussions,contends and geological practice,these problems will be solved gradually.
