Polychaete serpulids are globally distributed tubeworms mostly in marine environments from Late Triassic to modem time. These calcareous tubeworms could be rock-forming, reef-building, or a principal fouling organism ...Polychaete serpulids are globally distributed tubeworms mostly in marine environments from Late Triassic to modem time. These calcareous tubeworms could be rock-forming, reef-building, or a principal fouling organism in harbor and bays. Car- bonates of the Paleogene Kalatar Formation in southwest Tarim Basin yield abundant serpulid fossils, which, together with oyster fossils, constitute the characteristic fossil assemblage of the Kalatar Formation. Other common fossils include bivalves, gastropods, ostracods, echinoderms, and bryozoans. Lithologies that yielded serpulid fossils are characterized by micritic bio- clastic limestone, sandy limestone, and shelly limestone, indicating a semi-restricted to open shallow marine environment with medium to low water energy. The research data about serpulids and their fossil materials from China are relatively rare. Based on the studies of tbssils taxonomy, community palaeoecology, and fossil taphonomy, this paper analyzed and studied the types, occurrence, distribution, and morphological characteristics of serpulids and their palaeoecological features in the Kalatar For- mation. Two serpulid community compositions were recognized in the Kalatar Formation, including a rock-forming Ditrupa community and a cluster-growth Propomatoceros community. The Ditrupa community was distributed in coastal environment of the west Kunlun piedmont, lived on sandy hard substrates with little mud, and rarely occurred in lagoon and tidal settings. The Propomatoceros community occurred in offshore middle carbonate ramp in the piedmont of the south Tianshan Moun- tains and in offshore shelf in the piedmont of the west Kunlun Mountains. According to the analysis on the host-rock litholo- gies, preservation and symbionts, it is inferred that serpulids in the Kalatar Formation grew on the oyster shell or other hard substrate, and they did not form reefs or bioherms.展开更多
Due to deep burial of Precambrian in Tarim Basin,no breakthrough in the hydrocarbon exploration has been achieved from these strata,and development of high-quality source rocks is also uncertain.More than 30 explorato...Due to deep burial of Precambrian in Tarim Basin,no breakthrough in the hydrocarbon exploration has been achieved from these strata,and development of high-quality source rocks is also uncertain.More than 30 exploratory wells have been drilled in the southwest Tarim Basin and the pediment region of Kunlun Mountains with a total area of more than 100103 km2.Though some marine oil/gas fields such as Hetianhe,Bashituopu,Yubei and Luosi 2 have been discovered,the Cambrian or Ordovician source rocks have not been drilled,and hydrocarbon source still remain controversial.Recently,a set of thick black shales and mudstones has been found in the southwest Tarim Basin.The total thickness of mudstones is more than 140 m,and the total organic carbon mainly ranges from 0.6%to 1.9%with an average of 1.0%.Tmax is from 490C to 520C,equivalent to Ro from 1.99%to 2.99%.Pyrites are very rich in mudstone.According to stratigraphic contact relationship and isotopic chronology,this mudstone may have the age of more than 517 Ma,and is tentatively named as the“Western Kunlun black rock series”.Through the plate tectonic analysis,this set of thick black mudstones is possibly distributed widely in the southwest Tarim Basin,and its formation may be controlled by the aulacogen.This set of black mudstones may be an important source rocks in the southwest Tarim Basin,which suggest that the Precambrian-Cambrian strata in Tarim Basin has geological conditions for hydrocarbon accumulations.This discovery of the black thick mudstones in the southwest Tarim Basin will promote hydrocarbon exploration in the deep and ultra-deep strata of the Tarim Basin.展开更多
Based on lots of field investigations and comprehensive interpretations of seismic profiles with outcrop cross-sections, this paper shows that the foreland belts surrounding the Southwest Tarim Foreland Basin have the...Based on lots of field investigations and comprehensive interpretations of seismic profiles with outcrop cross-sections, this paper shows that the foreland belts surrounding the Southwest Tarim Foreland Basin have the regularity of segmentation along the strike of foreland belts. There are many thin-skinned thrusting systems thrusting from mountains to the basin and the arcuate back-thrusting systems to the mountains distributed at intervals in the front of West Kunlun-Pamir and Southern Tianshan. Between thrusting and back-thrusting systems, the strike-slip faults developed. The northeast uplifts and depressions of Southwest Tarim Basin correspond with the segmentation of foreland basin. The thin-skinned thrusting system is formed in the case that the thickness of sedimentary covers is less than 10 km in depth where the basement is an uplift belt in general. The back-thrusting systems and triangle zones are formed in the case that the thickness of sedimentary covers is larger than 8 km in depth where the basement is a depression zone. The main mechanics of segmentation of foreland basin are the difference of mountain uplift and deformation rate along the longitude of the mountains, the huge sedimentary rocks in different depression centers, the uplift belts and depression zones in the basement rocks, and multi-displaced weak layers in the foreland basin. The segmentation of Southwest Tarim Foreland Basin is due to the intra-plate deformation of re-orogenies of West Kunlun-Pamir and Southwest Tianshan and the co-related deformation between mountains and basement of basin since Neocene.展开更多
Kezilesu Group of the Lower Cretaceous located along the belt of Wuqia-Wuyitakein the Southwest Depression of Tarim Basin, a sequence as thick as 1000 metres, hadbeen considered as a sediment of lake-shore delta or la...Kezilesu Group of the Lower Cretaceous located along the belt of Wuqia-Wuyitakein the Southwest Depression of Tarim Basin, a sequence as thick as 1000 metres, hadbeen considered as a sediment of lake-shore delta or lake-shore sand barrier by thepredecessors in their conclusions. However, on the basis of detailed field and indoorstudies on Kangsu section of Wuqia County and Wuyitake section of Arctau County,展开更多
基金supported by National Natural Science Foundation of China(Grant Nos. 40872078,40976030)Knowledge Innovation Program of South China Sea Institute of Oceanology (Grant No. LYQY200806)the Research Project of Tarim Oilfield Company (Grant No. 41009080051)
文摘Polychaete serpulids are globally distributed tubeworms mostly in marine environments from Late Triassic to modem time. These calcareous tubeworms could be rock-forming, reef-building, or a principal fouling organism in harbor and bays. Car- bonates of the Paleogene Kalatar Formation in southwest Tarim Basin yield abundant serpulid fossils, which, together with oyster fossils, constitute the characteristic fossil assemblage of the Kalatar Formation. Other common fossils include bivalves, gastropods, ostracods, echinoderms, and bryozoans. Lithologies that yielded serpulid fossils are characterized by micritic bio- clastic limestone, sandy limestone, and shelly limestone, indicating a semi-restricted to open shallow marine environment with medium to low water energy. The research data about serpulids and their fossil materials from China are relatively rare. Based on the studies of tbssils taxonomy, community palaeoecology, and fossil taphonomy, this paper analyzed and studied the types, occurrence, distribution, and morphological characteristics of serpulids and their palaeoecological features in the Kalatar For- mation. Two serpulid community compositions were recognized in the Kalatar Formation, including a rock-forming Ditrupa community and a cluster-growth Propomatoceros community. The Ditrupa community was distributed in coastal environment of the west Kunlun piedmont, lived on sandy hard substrates with little mud, and rarely occurred in lagoon and tidal settings. The Propomatoceros community occurred in offshore middle carbonate ramp in the piedmont of the south Tianshan Moun- tains and in offshore shelf in the piedmont of the west Kunlun Mountains. According to the analysis on the host-rock litholo- gies, preservation and symbionts, it is inferred that serpulids in the Kalatar Formation grew on the oyster shell or other hard substrate, and they did not form reefs or bioherms.
基金The work was supported by the National Science and Technology Major Project of China(No.2016ZX05004-004)PetroChina Project(Comprehensive petroleum geology study as well as optimazation of replacement fields and risk target of evaluation in Sinian Cambrian in Tarim Basin).
文摘Due to deep burial of Precambrian in Tarim Basin,no breakthrough in the hydrocarbon exploration has been achieved from these strata,and development of high-quality source rocks is also uncertain.More than 30 exploratory wells have been drilled in the southwest Tarim Basin and the pediment region of Kunlun Mountains with a total area of more than 100103 km2.Though some marine oil/gas fields such as Hetianhe,Bashituopu,Yubei and Luosi 2 have been discovered,the Cambrian or Ordovician source rocks have not been drilled,and hydrocarbon source still remain controversial.Recently,a set of thick black shales and mudstones has been found in the southwest Tarim Basin.The total thickness of mudstones is more than 140 m,and the total organic carbon mainly ranges from 0.6%to 1.9%with an average of 1.0%.Tmax is from 490C to 520C,equivalent to Ro from 1.99%to 2.99%.Pyrites are very rich in mudstone.According to stratigraphic contact relationship and isotopic chronology,this mudstone may have the age of more than 517 Ma,and is tentatively named as the“Western Kunlun black rock series”.Through the plate tectonic analysis,this set of thick black mudstones is possibly distributed widely in the southwest Tarim Basin,and its formation may be controlled by the aulacogen.This set of black mudstones may be an important source rocks in the southwest Tarim Basin,which suggest that the Precambrian-Cambrian strata in Tarim Basin has geological conditions for hydrocarbon accumulations.This discovery of the black thick mudstones in the southwest Tarim Basin will promote hydrocarbon exploration in the deep and ultra-deep strata of the Tarim Basin.
基金supported by the National Major Fundamental Research and Development Project(Grant No.G1999043305)the National Natural Science Foundation of China(Grant Nos.49872075 and 49834005).
文摘Based on lots of field investigations and comprehensive interpretations of seismic profiles with outcrop cross-sections, this paper shows that the foreland belts surrounding the Southwest Tarim Foreland Basin have the regularity of segmentation along the strike of foreland belts. There are many thin-skinned thrusting systems thrusting from mountains to the basin and the arcuate back-thrusting systems to the mountains distributed at intervals in the front of West Kunlun-Pamir and Southern Tianshan. Between thrusting and back-thrusting systems, the strike-slip faults developed. The northeast uplifts and depressions of Southwest Tarim Basin correspond with the segmentation of foreland basin. The thin-skinned thrusting system is formed in the case that the thickness of sedimentary covers is less than 10 km in depth where the basement is an uplift belt in general. The back-thrusting systems and triangle zones are formed in the case that the thickness of sedimentary covers is larger than 8 km in depth where the basement is a depression zone. The main mechanics of segmentation of foreland basin are the difference of mountain uplift and deformation rate along the longitude of the mountains, the huge sedimentary rocks in different depression centers, the uplift belts and depression zones in the basement rocks, and multi-displaced weak layers in the foreland basin. The segmentation of Southwest Tarim Foreland Basin is due to the intra-plate deformation of re-orogenies of West Kunlun-Pamir and Southwest Tianshan and the co-related deformation between mountains and basement of basin since Neocene.
文摘Kezilesu Group of the Lower Cretaceous located along the belt of Wuqia-Wuyitakein the Southwest Depression of Tarim Basin, a sequence as thick as 1000 metres, hadbeen considered as a sediment of lake-shore delta or lake-shore sand barrier by thepredecessors in their conclusions. However, on the basis of detailed field and indoorstudies on Kangsu section of Wuqia County and Wuyitake section of Arctau County,
