There are abundant Bajocian—Tithonian bivalves in the main ridge of the Tanggula Mountains of northern Qinghai—Xizang Plateau, China. After figuring the common and coeval species between Tanggula and other areas (Fi...There are abundant Bajocian—Tithonian bivalves in the main ridge of the Tanggula Mountains of northern Qinghai—Xizang Plateau, China. After figuring the common and coeval species between Tanggula and other areas (Fig. 1), and tracing the temporal and spacial historical distribution of the bivalves very capable of dispersion, some Jurassic bivalve biogeographic items, particularly the biogeographic relations, have been lit up. In the known 21 taxa of the Jurassic Pectinoida and Ostreoida from the main ridge of the Tanggula Mountains, there are 12 (57%) common and coeval species in northern Tethys, 13 (62%) common and coeval species in southern Tethys and 12 (57%) in Kachchh—southern Xizang area. It has demonstrated that there existed intermigration of bivalves between Tanggula and various parts of Tethys. Although there is no coeval species between Tanggula and western Australia, in these two areas there exist 6 (29%) close range common species of which 4 (19%) coevaity existed in western Australia and India Plate. Tanggula fauna is, therefore, still very close to that of western Australia. However, there are 15 (71%) common and 14 (67%) coevality species between the main ridge of the Tanggula Mountains and northwestern Europe, among the common species, 8 (38%) ones have lower limitation (first occurrence) in northwestern Europe but only 2 (10%) taxa are older in the main ridge of the Tanggula Mountains. It is very clear that pectinite and ostrea fauna of Tethys, particularly the main ridge of the Tanggula Mountains and Europe had very close relation and most Tanggula’s or northern Tethyan taxa migrated from northwestern Europe.展开更多
A stratigraphic and depositional filling modal of Triassic—Jurassic North Tarim foreland basin system is erected, through synthetic analysis of geological setting, depositional provenance, sequence stratigraphy, and ...A stratigraphic and depositional filling modal of Triassic—Jurassic North Tarim foreland basin system is erected, through synthetic analysis of geological setting, depositional provenance, sequence stratigraphy, and quantitative tectonic stratigraphy. The result suggests that the major factors controlling formation and evolution of the system are oblique collision and convergence of different plates, and favorite hydrocarbon plays is predicted.The geological setting analysis emphasizes the historical succession of the foreland basin system formation and evolution. The tectonic setting analysis sketchy outlines formation of the system and tectonic setting of its successive evolution. The sedimentary geology analysis reveals the uplift and subsidence of the basin basement a seesaw style movement.展开更多
The Middle Jurassic system is well developed and exposed in western Liaoning Province including two formations,the Tiaojishan Formation and the Haifanggou Formation.The Tiaojishan Formation is represented by intermedi...The Middle Jurassic system is well developed and exposed in western Liaoning Province including two formations,the Tiaojishan Formation and the Haifanggou Formation.The Tiaojishan Formation is represented by intermediate extrusive and pyroclastic rocks,with intercalations of basic volcanic and sedimentary rocks.Diverse silicified wood specimens were recovered from this formation in Lamaying,展开更多
Abundant well-preserved Late Jurassic-Early Cretaceous radiolarian fossils were extracted from 31 bedded green chert samples collected from Zhilong section,Gyangse,southern Tibet.This
This paper analyses the sequence stratigraphy and palaeogeography of the Early and early Middle Jurassic coal measures in the Turpan-Hami Basin, northwestern China.The controls of the palaeogeography and sequence stra...This paper analyses the sequence stratigraphy and palaeogeography of the Early and early Middle Jurassic coal measures in the Turpan-Hami Basin, northwestern China.The controls of the palaeogeography and sequence stratigraphy on the coal accumulation in this basin have been discussed.The results show that the coal measures were formed in a fluvial-delta-lacustrine sedimentary system,and a total of 4 third-order sequences were developed,展开更多
Previous studies of coal sequence stratigraphy have concentrated on coals associated with paralic depositional systems.Little attention has been paid to their counterparts in non-marine intra-mountain coal basins.The ...Previous studies of coal sequence stratigraphy have concentrated on coals associated with paralic depositional systems.Little attention has been paid to their counterparts in non-marine intra-mountain coal basins.The northern Qaidam Basin of northwestern China has been extensively developed with abundant oil and gas as well as coal resources in its Jurassic non-marine successions.A total of six sedimentary systems of the Early and Middle Jurassic展开更多
Nazimskaya oil zone is situated in Khanty-Mansiysk autonomous district.It covers two oil fields: Srednenazimskoe and Galyanovskoe,and has rather wide stratigraphical range of oil content(Paleozoic -lower Cretaceous de...Nazimskaya oil zone is situated in Khanty-Mansiysk autonomous district.It covers two oil fields: Srednenazimskoe and Galyanovskoe,and has rather wide stratigraphical range of oil content(Paleozoic -lower Cretaceous deposits).However,it is suggested that the widespread Bazhenovo-Upper Abalak oil subcomplex(upper Jurassic) in Nazimskaya oil zone is the most perspective object.Current goal of research is to identify zones of superior展开更多
Qiangtang basin The north margin of the Qiangtang Basin, which located at the north Tibet region,is Lazhulong\|Xijinwulan (also named Jinshajiang River) suture zone (connect zone), and the south margin is Bangong Lake...Qiangtang basin The north margin of the Qiangtang Basin, which located at the north Tibet region,is Lazhulong\|Xijinwulan (also named Jinshajiang River) suture zone (connect zone), and the south margin is Bangong Lake—Dingqing (Nujiang River) suture zone (connect zone). The West End of the basin is gradually convergent at the West Side from Duoma about 80°meridian, and the East End may reach Muta area at about 95°meridian. According to the Jurassic strata development, the basin could be divided into three parts such the north Qiangtang depression, the Central uplift and the south Qiangtang depression as the first\|order tectonic unit. The direction of marine transgression is from the south of the basin to the north. The Jurassic strata of the basin are mainly marine sediments. The hydrocarbon source rocks occurred in Buqu Formation of the middle Jurassic and Suowa Formation of the upper Jurassic are of important potential for oil & gas exploration, and the hydrocarbon source rock in Quse Formation of the lower Jurassic for this is secondary due to localized distribution in the basin.展开更多
The complex investigation of the Bathonian sedimentary deposits in central regions of the WestSiberian basin was done.On the basis both of lithofacial analysis of core clefts and the geophysical investigation data and...The complex investigation of the Bathonian sedimentary deposits in central regions of the WestSiberian basin was done.On the basis both of lithofacial analysis of core clefts and the geophysical investigation data and taking into account the tectonic features of the Jurassic structural storey the sedimenttological model of deposits was built and the main regularities of its building were identified.At the initial stage the framework of alluvial lower plain展开更多
The Qiangtang Basin located in northern Tibet is a Jurassic foreland basin, whereas the sedimentation for the arc\|basin system during the Late Triassic. Paleomagnetic sampling sites and sections include the Lower Jur...The Qiangtang Basin located in northern Tibet is a Jurassic foreland basin, whereas the sedimentation for the arc\|basin system during the Late Triassic. Paleomagnetic sampling sites and sections include the Lower Jurassic section in Juhuashan, Shuanhu district, the Middle and Upper Jurassic section in Nadigangri Mountain and the Lower Cretaceous section in Abushan, Shuanhu district. The Lower Jurassic Nadigangri Fm. is composed of tuffaceous volcanic rocks and turbidite (lower) and purple clastic rocks. The Middle Jurassic consists of Quemocuo Fm. purple clastics , Buqu Fm. carbonates and Xiali Fm. gypsum\|bearing varicolored clastics.The Upper Jurassic includes Suowa Fm. carbonates and Xueshan Fm. purple clastics. The Lower Cretaceous Abushan Fm. is lacustrine clastics.1723 oriented paleomagnetic samples of Jurassic and Cretaceous strata were collected in 1997.The sampling sections is located in Shuanhu district of northern Tibet. Although it is unlikely that the sections studied formed by constant and continuous deposition, field evidence indicates no major breaks in the Jurassic sedimentation, except early Bajocian stage. Based on sections of actual survey, all sampling was done using a portable gas\|powered core drill, and cores were oriented with magnetic compass and inclinometer. Samples were obtained at common stratigraphic spacing of 0 5～5m, partly 5cm at some important geological boundary\|surfaces and beds/members. 25mm diameter and 20～50mm length paleomagnetic core samples were drilled in cropping field. The measuring of most samples was completed at the China Academy of Geosciences Paleomagnetic Laboratory using a type DSM\|2 digital rotational magnetometer (its sensitivity of reaching 10 -5 A/m) made by SCHONSTEDT Company of U.S.A., and SCHONSTEDT TSD\|1 for thermal demagnetization. The apparatus used for AF demagnetization was a commercial (SCHONSTEDT GSD\|5)instrument, capable of reaching 100mT peak field. 10% of total measuring samples were completed at the Beijing Geological Institute Paleomagnetic Laboratory of China Academy of Sciences using a type 2G\|755R magnetometer made by Superconducting Technology for weak magnetized samples (sensitivity of reaching 10 -8 A/m). Most samples were stepwise thermally demagnetized, at 50℃ intervals from 100 to 700℃.展开更多
The Tyrannosauridae,which is characterized by specialized pachydont dentition and putative bone-cracking predatory strategies,is one of the most extensively studied theropod lineages.Although tooth replacement pattern...The Tyrannosauridae,which is characterized by specialized pachydont dentition and putative bone-cracking predatory strategies,is one of the most extensively studied theropod lineages.Although tooth replacement patterns,crucial for understanding feeding behaviors,have been thoroughly studied in this group,studies on non-tyrannosaurid tyrannosauroids are relatively scarce.This study utilizes high-resolution CT data to investigate the tooth replacement pattern in two specimens of Guanlong wucaii,a Late Jurassic tyrannosauroid,and provides insights into the evolution of tooth replacement across Tyrannosauroidea.Second-generation replacement teeth,a rarity observed mainly in giant predatory theropods(e.g.some tyrannosaurids),were detected in the dentary dentition of the juvenile Guanlong.Zahnreihen reconstructions display a consistent cephalad alternating tooth replacement pattern in the maxilla and the dentary of both of the examined individuals,with Z-spacing values exceeding 2.0.As Guanlong grows,the Z-spacing value in the maxillary dentition increases,resembling the ontogenetic changes documented in the Tyrannosauridae.Additionally,like Tarbosaurus,Guanlong also displays a discontinuity between the tooth replacement waves at the premaxilla-maxilla boundary.This study thus demonstrates that some tyrannosaurid-like tooth replacement patterns were acquired before the origin of the Tyrannosauridae.展开更多
Several tritylodontid taxa have been reported from the Upper Jurassic of the Wucaiwan area in the Junggar Basin of Xinjiang,northwestern China,including Yuanotherium minor.The original study described the partially pr...Several tritylodontid taxa have been reported from the Upper Jurassic of the Wucaiwan area in the Junggar Basin of Xinjiang,northwestern China,including Yuanotherium minor.The original study described the partially preserved postcanine teeth in the middle of the left upper maxilla.After detailed re-examination of the specimen and by CT scanning,3D reconstruction,and scanning electron microscopy observations,we provided a more detailed description of the osteology,neurosensory,and tooth wear pattern for all the bones preserved in this specimen and clarified some characters.Based on new information about the cusp wear pattern,the chewing movement pattern of the dentition and detailed cusp morphology,we discussed the cuspal homology of upper cheek teeth of tritylodontids and postulate a standardized method for cusp identification.We hypothesize that the unique maxilla characteristics furnish the evidence for transitional stages about the evolution of the upper jaw-palate structure in tritylodontids.展开更多
The Ceno\|Tethys is a southern branch of the Tethyan ocean and existed in the Mesozoic and early Cenozoic times. The evolution of the Ceno\|Tethys has been discussed based mainly on geological and paleontological data...The Ceno\|Tethys is a southern branch of the Tethyan ocean and existed in the Mesozoic and early Cenozoic times. The evolution of the Ceno\|Tethys has been discussed based mainly on geological and paleontological data obtained from shallow marine sediments on the both sides of the ocean. Pelagic sediments deposited in a deep ocean basin of the Ceno\|Tethys are often incorporated in suture zones. However, geological and paleontological data from the pelagic sediments, which enable us to elucidate the paleoceanography and tectonic evolution of the Ceno\|Tethys, are still limited. The Xialu chert crops out about 30 km south of Xigaze and occupies the southern marginal part of the E—W trending Yarlung Zangbo Suture zone. As a result of radiolarian biostratigraphic research along two continuous sections, we identified seven different aged radiolarian assemblages from pelagic and hemipelagic sediments ranging early Middle Jurassic (Aalenian) to Early Cretaceous. The Aalenian radiolarian fauna is the oldest known record so far for the Xialu chert. It is noteworthy to point out that the fauna came from a chert sample which contains no terrigenous elements other than clay minerals. There is a possibility that radiolarian faunas older than Aalenian age will be discovered from the Xialu chert in the future.展开更多
The Kurosegawa belt forms a relatively narrow terrane that can be traced continuously throughout southwest and central Japan.The major constituent continental fragments of the Kurosegawa belt include Early Paleozoic g...The Kurosegawa belt forms a relatively narrow terrane that can be traced continuously throughout southwest and central Japan.The major constituent continental fragments of the Kurosegawa belt include Early Paleozoic granitic rocks,high-grade展开更多
Jurassic deposits of the Malayan Peninsula (Thailand) are stratigraphically limited to Toarcian and Aalenian only(Meesook & Sha,2010,and literature cited therein).These are represented by wide spectrum of both cla...Jurassic deposits of the Malayan Peninsula (Thailand) are stratigraphically limited to Toarcian and Aalenian only(Meesook & Sha,2010,and literature cited therein).These are represented by wide spectrum of both clastic and carbonate rocks with full development展开更多
文摘There are abundant Bajocian—Tithonian bivalves in the main ridge of the Tanggula Mountains of northern Qinghai—Xizang Plateau, China. After figuring the common and coeval species between Tanggula and other areas (Fig. 1), and tracing the temporal and spacial historical distribution of the bivalves very capable of dispersion, some Jurassic bivalve biogeographic items, particularly the biogeographic relations, have been lit up. In the known 21 taxa of the Jurassic Pectinoida and Ostreoida from the main ridge of the Tanggula Mountains, there are 12 (57%) common and coeval species in northern Tethys, 13 (62%) common and coeval species in southern Tethys and 12 (57%) in Kachchh—southern Xizang area. It has demonstrated that there existed intermigration of bivalves between Tanggula and various parts of Tethys. Although there is no coeval species between Tanggula and western Australia, in these two areas there exist 6 (29%) close range common species of which 4 (19%) coevaity existed in western Australia and India Plate. Tanggula fauna is, therefore, still very close to that of western Australia. However, there are 15 (71%) common and 14 (67%) coevality species between the main ridge of the Tanggula Mountains and northwestern Europe, among the common species, 8 (38%) ones have lower limitation (first occurrence) in northwestern Europe but only 2 (10%) taxa are older in the main ridge of the Tanggula Mountains. It is very clear that pectinite and ostrea fauna of Tethys, particularly the main ridge of the Tanggula Mountains and Europe had very close relation and most Tanggula’s or northern Tethyan taxa migrated from northwestern Europe.
文摘A stratigraphic and depositional filling modal of Triassic—Jurassic North Tarim foreland basin system is erected, through synthetic analysis of geological setting, depositional provenance, sequence stratigraphy, and quantitative tectonic stratigraphy. The result suggests that the major factors controlling formation and evolution of the system are oblique collision and convergence of different plates, and favorite hydrocarbon plays is predicted.The geological setting analysis emphasizes the historical succession of the foreland basin system formation and evolution. The tectonic setting analysis sketchy outlines formation of the system and tectonic setting of its successive evolution. The sedimentary geology analysis reveals the uplift and subsidence of the basin basement a seesaw style movement.
文摘The Middle Jurassic system is well developed and exposed in western Liaoning Province including two formations,the Tiaojishan Formation and the Haifanggou Formation.The Tiaojishan Formation is represented by intermediate extrusive and pyroclastic rocks,with intercalations of basic volcanic and sedimentary rocks.Diverse silicified wood specimens were recovered from this formation in Lamaying,
文摘Abundant well-preserved Late Jurassic-Early Cretaceous radiolarian fossils were extracted from 31 bedded green chert samples collected from Zhilong section,Gyangse,southern Tibet.This
文摘This paper analyses the sequence stratigraphy and palaeogeography of the Early and early Middle Jurassic coal measures in the Turpan-Hami Basin, northwestern China.The controls of the palaeogeography and sequence stratigraphy on the coal accumulation in this basin have been discussed.The results show that the coal measures were formed in a fluvial-delta-lacustrine sedimentary system,and a total of 4 third-order sequences were developed,
文摘Previous studies of coal sequence stratigraphy have concentrated on coals associated with paralic depositional systems.Little attention has been paid to their counterparts in non-marine intra-mountain coal basins.The northern Qaidam Basin of northwestern China has been extensively developed with abundant oil and gas as well as coal resources in its Jurassic non-marine successions.A total of six sedimentary systems of the Early and Middle Jurassic
文摘Nazimskaya oil zone is situated in Khanty-Mansiysk autonomous district.It covers two oil fields: Srednenazimskoe and Galyanovskoe,and has rather wide stratigraphical range of oil content(Paleozoic -lower Cretaceous deposits).However,it is suggested that the widespread Bazhenovo-Upper Abalak oil subcomplex(upper Jurassic) in Nazimskaya oil zone is the most perspective object.Current goal of research is to identify zones of superior
文摘Qiangtang basin The north margin of the Qiangtang Basin, which located at the north Tibet region,is Lazhulong\|Xijinwulan (also named Jinshajiang River) suture zone (connect zone), and the south margin is Bangong Lake—Dingqing (Nujiang River) suture zone (connect zone). The West End of the basin is gradually convergent at the West Side from Duoma about 80°meridian, and the East End may reach Muta area at about 95°meridian. According to the Jurassic strata development, the basin could be divided into three parts such the north Qiangtang depression, the Central uplift and the south Qiangtang depression as the first\|order tectonic unit. The direction of marine transgression is from the south of the basin to the north. The Jurassic strata of the basin are mainly marine sediments. The hydrocarbon source rocks occurred in Buqu Formation of the middle Jurassic and Suowa Formation of the upper Jurassic are of important potential for oil & gas exploration, and the hydrocarbon source rock in Quse Formation of the lower Jurassic for this is secondary due to localized distribution in the basin.
文摘The complex investigation of the Bathonian sedimentary deposits in central regions of the WestSiberian basin was done.On the basis both of lithofacial analysis of core clefts and the geophysical investigation data and taking into account the tectonic features of the Jurassic structural storey the sedimenttological model of deposits was built and the main regularities of its building were identified.At the initial stage the framework of alluvial lower plain
文摘The Qiangtang Basin located in northern Tibet is a Jurassic foreland basin, whereas the sedimentation for the arc\|basin system during the Late Triassic. Paleomagnetic sampling sites and sections include the Lower Jurassic section in Juhuashan, Shuanhu district, the Middle and Upper Jurassic section in Nadigangri Mountain and the Lower Cretaceous section in Abushan, Shuanhu district. The Lower Jurassic Nadigangri Fm. is composed of tuffaceous volcanic rocks and turbidite (lower) and purple clastic rocks. The Middle Jurassic consists of Quemocuo Fm. purple clastics , Buqu Fm. carbonates and Xiali Fm. gypsum\|bearing varicolored clastics.The Upper Jurassic includes Suowa Fm. carbonates and Xueshan Fm. purple clastics. The Lower Cretaceous Abushan Fm. is lacustrine clastics.1723 oriented paleomagnetic samples of Jurassic and Cretaceous strata were collected in 1997.The sampling sections is located in Shuanhu district of northern Tibet. Although it is unlikely that the sections studied formed by constant and continuous deposition, field evidence indicates no major breaks in the Jurassic sedimentation, except early Bajocian stage. Based on sections of actual survey, all sampling was done using a portable gas\|powered core drill, and cores were oriented with magnetic compass and inclinometer. Samples were obtained at common stratigraphic spacing of 0 5～5m, partly 5cm at some important geological boundary\|surfaces and beds/members. 25mm diameter and 20～50mm length paleomagnetic core samples were drilled in cropping field. The measuring of most samples was completed at the China Academy of Geosciences Paleomagnetic Laboratory using a type DSM\|2 digital rotational magnetometer (its sensitivity of reaching 10 -5 A/m) made by SCHONSTEDT Company of U.S.A., and SCHONSTEDT TSD\|1 for thermal demagnetization. The apparatus used for AF demagnetization was a commercial (SCHONSTEDT GSD\|5)instrument, capable of reaching 100mT peak field. 10% of total measuring samples were completed at the Beijing Geological Institute Paleomagnetic Laboratory of China Academy of Sciences using a type 2G\|755R magnetometer made by Superconducting Technology for weak magnetized samples (sensitivity of reaching 10 -8 A/m). Most samples were stepwise thermally demagnetized, at 50℃ intervals from 100 to 700℃.
文摘The Tyrannosauridae,which is characterized by specialized pachydont dentition and putative bone-cracking predatory strategies,is one of the most extensively studied theropod lineages.Although tooth replacement patterns,crucial for understanding feeding behaviors,have been thoroughly studied in this group,studies on non-tyrannosaurid tyrannosauroids are relatively scarce.This study utilizes high-resolution CT data to investigate the tooth replacement pattern in two specimens of Guanlong wucaii,a Late Jurassic tyrannosauroid,and provides insights into the evolution of tooth replacement across Tyrannosauroidea.Second-generation replacement teeth,a rarity observed mainly in giant predatory theropods(e.g.some tyrannosaurids),were detected in the dentary dentition of the juvenile Guanlong.Zahnreihen reconstructions display a consistent cephalad alternating tooth replacement pattern in the maxilla and the dentary of both of the examined individuals,with Z-spacing values exceeding 2.0.As Guanlong grows,the Z-spacing value in the maxillary dentition increases,resembling the ontogenetic changes documented in the Tyrannosauridae.Additionally,like Tarbosaurus,Guanlong also displays a discontinuity between the tooth replacement waves at the premaxilla-maxilla boundary.This study thus demonstrates that some tyrannosaurid-like tooth replacement patterns were acquired before the origin of the Tyrannosauridae.
文摘Several tritylodontid taxa have been reported from the Upper Jurassic of the Wucaiwan area in the Junggar Basin of Xinjiang,northwestern China,including Yuanotherium minor.The original study described the partially preserved postcanine teeth in the middle of the left upper maxilla.After detailed re-examination of the specimen and by CT scanning,3D reconstruction,and scanning electron microscopy observations,we provided a more detailed description of the osteology,neurosensory,and tooth wear pattern for all the bones preserved in this specimen and clarified some characters.Based on new information about the cusp wear pattern,the chewing movement pattern of the dentition and detailed cusp morphology,we discussed the cuspal homology of upper cheek teeth of tritylodontids and postulate a standardized method for cusp identification.We hypothesize that the unique maxilla characteristics furnish the evidence for transitional stages about the evolution of the upper jaw-palate structure in tritylodontids.
文摘The Ceno\|Tethys is a southern branch of the Tethyan ocean and existed in the Mesozoic and early Cenozoic times. The evolution of the Ceno\|Tethys has been discussed based mainly on geological and paleontological data obtained from shallow marine sediments on the both sides of the ocean. Pelagic sediments deposited in a deep ocean basin of the Ceno\|Tethys are often incorporated in suture zones. However, geological and paleontological data from the pelagic sediments, which enable us to elucidate the paleoceanography and tectonic evolution of the Ceno\|Tethys, are still limited. The Xialu chert crops out about 30 km south of Xigaze and occupies the southern marginal part of the E—W trending Yarlung Zangbo Suture zone. As a result of radiolarian biostratigraphic research along two continuous sections, we identified seven different aged radiolarian assemblages from pelagic and hemipelagic sediments ranging early Middle Jurassic (Aalenian) to Early Cretaceous. The Aalenian radiolarian fauna is the oldest known record so far for the Xialu chert. It is noteworthy to point out that the fauna came from a chert sample which contains no terrigenous elements other than clay minerals. There is a possibility that radiolarian faunas older than Aalenian age will be discovered from the Xialu chert in the future.
文摘The Kurosegawa belt forms a relatively narrow terrane that can be traced continuously throughout southwest and central Japan.The major constituent continental fragments of the Kurosegawa belt include Early Paleozoic granitic rocks,high-grade
文摘Jurassic deposits of the Malayan Peninsula (Thailand) are stratigraphically limited to Toarcian and Aalenian only(Meesook & Sha,2010,and literature cited therein).These are represented by wide spectrum of both clastic and carbonate rocks with full development
