Objective The Huashan group（composed of the lower Hongshansi Formation and the upper Liufangzui Formation）is an important Neoproterozoic stratigraphic unit along the northern margin of the Yangtze Block.Previous doc...Objective The Huashan group（composed of the lower Hongshansi Formation and the upper Liufangzui Formation）is an important Neoproterozoic stratigraphic unit along the northern margin of the Yangtze Block.Previous documents have focused on the geochronological and geochemical aspects of the Neoproterozoic sedimentary basin in the Dahongshan region.However.展开更多
During the Early-Middle Proterozoic era,three major lithostratigraphic unit associations,namely Hekou-Dahongshan,Dongchuan,and Kunyang-Huili Groups,were established for the metamorphosed volcanicsedimentary rocks expo...During the Early-Middle Proterozoic era,three major lithostratigraphic unit associations,namely Hekou-Dahongshan,Dongchuan,and Kunyang-Huili Groups,were established for the metamorphosed volcanicsedimentary rocks exposed in the southwestern Yangtze Block (SWYB).The integration of petrology, geochemistry and geochronology constrains tectonic framework and evolution of the SWYB,in which four sets of SHRIMP U-Pb zircon ages were obtained from the volcanic rocks interbedded within the Middle Proterozoic successions:1800-1600 Ma,1600-1300 Ma,1300-1100 Ma,and 1100-1000 Ma. Major and trace elemental analysis indicate that four key tectonic evolutionary stages,each coinciding with the above radiometric age set,of the SWYB during the Early-Middle Mesoproterozoic.The SWYB was characterized by an east-westerly trending rift in the Hekou,Dongshan,and Dongchuan areas,and separate basin-forming events during 1800-1600 Ma arid 1600-1300 Ma,respectively.In the SWYB,an intracontinental rift basin and a rift basin occurred in the Caiziyuan-Matang and Laowushan areas, respectively in 1300-1100 Ma ago.During 1100-1000 Ma,the SWYB was characterized by the closure of the Caiziyuan-Matang rift-ocean basin,collision between the Huili Blocks and Kunyang Blocks,and presence of volcanic ares in the Tianbaoshan and Fulingpen areas.Accordingly,the SWYB represents a new basin that records the relatively complete assembly process of the Rodina during the Early-Middle Mesoproterozoic era.展开更多
In this study, we report U–Pb and Lu–Hf isotopic data for zircons from the Mesozoic sandstones of the Upper Yangtze area, which provide critical constraints on the provenance of these sediments and further shed ligh...In this study, we report U–Pb and Lu–Hf isotopic data for zircons from the Mesozoic sandstones of the Upper Yangtze area, which provide critical constraints on the provenance of these sediments and further shed light on the crustal evolution of the Upper Yangtze block. The results of isotopic chronology indicate the following：（1） The provenances of the study area are very complex, and the tectonic evolution process is relatively closed.（2） The provenances are mainly Archean–Proterozoic crystalline basement or recycled material; Paleoproterozoic crustal accretion in the western margin of the Yangtze block and Neoproterozoic magmatic activities related to subduction of the western margin of the Yangtze block; early Cambrian oceanic magmatic activity, which resulted from the intraplate extension of the northern margin of the Yangtze block; late Ordovician–early Silurian magmatic activity in the northern Yangtze block and Hercynian–Indochina uplift and erosion during the Hercynian movement.（3） The Yangtze crustal growth is episodic, and an increasing amount of ancient recycled material became part of the magmatic activity, as the zircon U–Pb ages are relatively young.展开更多
The western margin of Yangtze block and southwestern Sanjiang region absorbed much attention from geologists. It has been proved that there occurred a series of plate subduction, collision, assembly, rifting and break...The western margin of Yangtze block and southwestern Sanjiang region absorbed much attention from geologists. It has been proved that there occurred a series of plate subduction, collision, assembly, rifting and breakup processes between them since Palaeozoic and the tectonic evolutionary relationship between them is clear. But in Proterozoic this kind of links between them became unclear. Did they undergo the assembly and breakup processes of the Rodinia super continent? This paper will take a primary discussion on this question on the basis of basement component, structure characteristics and magmatic activities.1\ Basement features\;(1) In western margin of Yangtze block its basement is composed of crystalline basement and folded basement, a so\|called double\|layer structure. The crystalline basement is made up of Kangding group, Pudeng Formation and Dibadu Formation, among them Kangding group is a representative and composed mainly of migmatite, compositing gneiss, hornblende schist and granulitite. The isotopic age of crystalline basement is older than 1900Ma, so its geological time is late Archaean to early Proterozoic. The folded basement is composed of Dahongshan group, Hekou group, Kunyang group, Huili group and Yanbian group. Their rock associations are made up mainly of spilite\|keratophyre formation, carbonate formation, clastic rock and clastic rock formation with some basic volcanic rocks. The folded basement is assigned to be early and middle Proterozoic (1000～1700M a).展开更多
Boli basin, between Yishu fracture belt and Dunmi fracture belt, is the biggest Mesozoic coal basin in the east of Heilongjiang Province. Now it is a fault-fold remnant basin. The basin’s shape is generally consisten...Boli basin, between Yishu fracture belt and Dunmi fracture belt, is the biggest Mesozoic coal basin in the east of Heilongjiang Province. Now it is a fault-fold remnant basin. The basin’s shape is generally consistent with the whole distribution of the cover folds, an arc protruding southwards. The basement of the basin can be divided into three fault blocks or structural units. The formation and evoluation of the basin in Mesozoic was determined by the basement fault blocks’ dis- placement features rusulted from by the movement of the edge faults and the main basement faults.展开更多
We analyzed the major and rare earth element compositions of siliceous deposits from the Upper Devonian Liujiang Formation,Lower Carboniferous Luzhai Formation,Lower-Middle Permian Sidazhai Formation and Tapi Formatio...We analyzed the major and rare earth element compositions of siliceous deposits from the Upper Devonian Liujiang Formation,Lower Carboniferous Luzhai Formation,Lower-Middle Permian Sidazhai Formation and Tapi Formation,which are widely distributed as bedded cherts in the interplatform basinal successions of the Youjiang Basin.The Liujiang Formation and Luzhai Formation cherts generally have high Al/(Al+Fe+Mn) values(0.38-0.94) and are non-hydrothermal cherts.These cherts are generally characterized by moderately negative Ce anomalies and high Y/Ho values relatived to PAAS,indicating that the Youjiang Basin might have evolved into an open rift basin during the Late Devonian-Early Carboniferous.The Sidazhai Formation cherts from Ziyun generally have high Al/(Al+Fe+Mn) values(0.60-0.78),suggesting negligible contribution from a hydrothermal component.The Sidazhai Formation cherts from Hechi and the Tapi Formation cherts from Malipo generally have low Al/(Al+Fe+Mn) values(0.09-0.41),indicating an intense hydrothermal input.Relatived to the Sidazhai Formation cherts,the Tapi Formation cherts have higher Ce/Ce*values(0.68±0.19) and lower Y/Ho values(41.83±13.27),which may be affected by the terrigenous input from the Vietnam Block.The Sidazhai Formation cherts from Ziyun and Hechi exhibit negative Ce anomalies(0.43±0.12,0.33±0.17,respectively) with high Y/Ho values(57.44±16.20,46.02±4.27,respectively),resembling the geochemical characteristics of open-ocean basin cherts.These cherts were deposited on a passive continental margin adjacent to the Babu branch ocean,which may have contributed to upwelling.Detailed spatial studies on geochemical characteristics of the Late Paleozoic cherts can unravel the evolution of the Youjiang Basin.展开更多
ABSTRACT： The widespread Neoproterozoic magmatism along the Yangtze block carries critical in- formation for understanding the Neoproterozoic evolution of the Yangtze block. In the northwestern margin of the Yangtze ...ABSTRACT： The widespread Neoproterozoic magmatism along the Yangtze block carries critical in- formation for understanding the Neoproterozoic evolution of the Yangtze block. In the northwestern margin of the Yangtze block, the Hannan （汉南） intrusive complex includes the Wudumen （五堵门）, Erliba （二里坝） and Zushidian （祖师殿） granitoids. Using LA-ICP-MS U-Pb zircon dating method, the Wudumen and Erliba granitoids yielded magma crystallization ages of 785±4 and 778±3 Ma, respectively. Samples from these three granitoids show variable SiO2 contents ranging from 58.8% to 72.6%. They are characterized by enrichment of Al2O3（14.97%-17.87%）, Na2O（3.80%-5.33%） and Sr （504ppm-741 ppm）, and depletion of Y （〈19 ppm） and HREE （e.g., Yb〈1.6 ppm）, resulting in high Sr/Y （29-161） and （La/Yb）N （7.3-27.8） ratios. The geochemical features of the granitoids are comparable with those of adakite. The granitoids have zircon εHdt） values of ＋3.65 to ＋10.05, whole-rock εNd（t） values of -0.09 to ＋2.98 and whole-rock initial ^87Sr/^86Sr ratios of 0.7034-0.7039, indicating that their magma was derived from a juvenile crustal source. Together with geochemical and Hf-Sr-Nd isotopic compositions, it is suggested that the granitoids formed in island-arc setting and originated from partial melting of a subducted oceanic slab. The results support a model that the Yangtze block was surrounded by ocean and arc magmatism in its northern and northwestern margins in Neoproterozoic.展开更多
基金financially supported by the National Natural Science Foundation of China(grant No. 41402103,41502114 and 41372124)
文摘Objective The Huashan group（composed of the lower Hongshansi Formation and the upper Liufangzui Formation）is an important Neoproterozoic stratigraphic unit along the northern margin of the Yangtze Block.Previous documents have focused on the geochronological and geochemical aspects of the Neoproterozoic sedimentary basin in the Dahongshan region.However.
基金grants from a 973 Program (2009CB421003)a National Resources Survey Project (1212010610213)a National Natural Science Foundation of China project (40773001).
文摘During the Early-Middle Proterozoic era,three major lithostratigraphic unit associations,namely Hekou-Dahongshan,Dongchuan,and Kunyang-Huili Groups,were established for the metamorphosed volcanicsedimentary rocks exposed in the southwestern Yangtze Block (SWYB).The integration of petrology, geochemistry and geochronology constrains tectonic framework and evolution of the SWYB,in which four sets of SHRIMP U-Pb zircon ages were obtained from the volcanic rocks interbedded within the Middle Proterozoic successions:1800-1600 Ma,1600-1300 Ma,1300-1100 Ma,and 1100-1000 Ma. Major and trace elemental analysis indicate that four key tectonic evolutionary stages,each coinciding with the above radiometric age set,of the SWYB during the Early-Middle Mesoproterozoic.The SWYB was characterized by an east-westerly trending rift in the Hekou,Dongshan,and Dongchuan areas,and separate basin-forming events during 1800-1600 Ma arid 1600-1300 Ma,respectively.In the SWYB,an intracontinental rift basin and a rift basin occurred in the Caiziyuan-Matang and Laowushan areas, respectively in 1300-1100 Ma ago.During 1100-1000 Ma,the SWYB was characterized by the closure of the Caiziyuan-Matang rift-ocean basin,collision between the Huili Blocks and Kunyang Blocks,and presence of volcanic ares in the Tianbaoshan and Fulingpen areas.Accordingly,the SWYB represents a new basin that records the relatively complete assembly process of the Rodina during the Early-Middle Mesoproterozoic era.
基金financially supported by the China Geological Survey(CGS,Grant No.DD20160183)the Major State Research Development Program of China(Grant No.2016YFC0600202)
文摘In this study, we report U–Pb and Lu–Hf isotopic data for zircons from the Mesozoic sandstones of the Upper Yangtze area, which provide critical constraints on the provenance of these sediments and further shed light on the crustal evolution of the Upper Yangtze block. The results of isotopic chronology indicate the following：（1） The provenances of the study area are very complex, and the tectonic evolution process is relatively closed.（2） The provenances are mainly Archean–Proterozoic crystalline basement or recycled material; Paleoproterozoic crustal accretion in the western margin of the Yangtze block and Neoproterozoic magmatic activities related to subduction of the western margin of the Yangtze block; early Cambrian oceanic magmatic activity, which resulted from the intraplate extension of the northern margin of the Yangtze block; late Ordovician–early Silurian magmatic activity in the northern Yangtze block and Hercynian–Indochina uplift and erosion during the Hercynian movement.（3） The Yangtze crustal growth is episodic, and an increasing amount of ancient recycled material became part of the magmatic activity, as the zircon U–Pb ages are relatively young.
文摘The western margin of Yangtze block and southwestern Sanjiang region absorbed much attention from geologists. It has been proved that there occurred a series of plate subduction, collision, assembly, rifting and breakup processes between them since Palaeozoic and the tectonic evolutionary relationship between them is clear. But in Proterozoic this kind of links between them became unclear. Did they undergo the assembly and breakup processes of the Rodinia super continent? This paper will take a primary discussion on this question on the basis of basement component, structure characteristics and magmatic activities.1\ Basement features\;(1) In western margin of Yangtze block its basement is composed of crystalline basement and folded basement, a so\|called double\|layer structure. The crystalline basement is made up of Kangding group, Pudeng Formation and Dibadu Formation, among them Kangding group is a representative and composed mainly of migmatite, compositing gneiss, hornblende schist and granulitite. The isotopic age of crystalline basement is older than 1900Ma, so its geological time is late Archaean to early Proterozoic. The folded basement is composed of Dahongshan group, Hekou group, Kunyang group, Huili group and Yanbian group. Their rock associations are made up mainly of spilite\|keratophyre formation, carbonate formation, clastic rock and clastic rock formation with some basic volcanic rocks. The folded basement is assigned to be early and middle Proterozoic (1000～1700M a).
文摘Boli basin, between Yishu fracture belt and Dunmi fracture belt, is the biggest Mesozoic coal basin in the east of Heilongjiang Province. Now it is a fault-fold remnant basin. The basin’s shape is generally consistent with the whole distribution of the cover folds, an arc protruding southwards. The basement of the basin can be divided into three fault blocks or structural units. The formation and evoluation of the basin in Mesozoic was determined by the basement fault blocks’ dis- placement features rusulted from by the movement of the edge faults and the main basement faults.
基金financially supported by National Natural Science Foundation of China (No. 41272120 and No. 40972078)
文摘We analyzed the major and rare earth element compositions of siliceous deposits from the Upper Devonian Liujiang Formation,Lower Carboniferous Luzhai Formation,Lower-Middle Permian Sidazhai Formation and Tapi Formation,which are widely distributed as bedded cherts in the interplatform basinal successions of the Youjiang Basin.The Liujiang Formation and Luzhai Formation cherts generally have high Al/(Al+Fe+Mn) values(0.38-0.94) and are non-hydrothermal cherts.These cherts are generally characterized by moderately negative Ce anomalies and high Y/Ho values relatived to PAAS,indicating that the Youjiang Basin might have evolved into an open rift basin during the Late Devonian-Early Carboniferous.The Sidazhai Formation cherts from Ziyun generally have high Al/(Al+Fe+Mn) values(0.60-0.78),suggesting negligible contribution from a hydrothermal component.The Sidazhai Formation cherts from Hechi and the Tapi Formation cherts from Malipo generally have low Al/(Al+Fe+Mn) values(0.09-0.41),indicating an intense hydrothermal input.Relatived to the Sidazhai Formation cherts,the Tapi Formation cherts have higher Ce/Ce*values(0.68±0.19) and lower Y/Ho values(41.83±13.27),which may be affected by the terrigenous input from the Vietnam Block.The Sidazhai Formation cherts from Ziyun and Hechi exhibit negative Ce anomalies(0.43±0.12,0.33±0.17,respectively) with high Y/Ho values(57.44±16.20,46.02±4.27,respectively),resembling the geochemical characteristics of open-ocean basin cherts.These cherts were deposited on a passive continental margin adjacent to the Babu branch ocean,which may have contributed to upwelling.Detailed spatial studies on geochemical characteristics of the Late Paleozoic cherts can unravel the evolution of the Youjiang Basin.
基金supported by the National Natural Science Foundation of China (Nos. 40773019 and 40821061)the Ministry of Education of China and the State Administration of Foreign Expert Affairs of China (No. B07039)
文摘ABSTRACT： The widespread Neoproterozoic magmatism along the Yangtze block carries critical in- formation for understanding the Neoproterozoic evolution of the Yangtze block. In the northwestern margin of the Yangtze block, the Hannan （汉南） intrusive complex includes the Wudumen （五堵门）, Erliba （二里坝） and Zushidian （祖师殿） granitoids. Using LA-ICP-MS U-Pb zircon dating method, the Wudumen and Erliba granitoids yielded magma crystallization ages of 785±4 and 778±3 Ma, respectively. Samples from these three granitoids show variable SiO2 contents ranging from 58.8% to 72.6%. They are characterized by enrichment of Al2O3（14.97%-17.87%）, Na2O（3.80%-5.33%） and Sr （504ppm-741 ppm）, and depletion of Y （〈19 ppm） and HREE （e.g., Yb〈1.6 ppm）, resulting in high Sr/Y （29-161） and （La/Yb）N （7.3-27.8） ratios. The geochemical features of the granitoids are comparable with those of adakite. The granitoids have zircon εHdt） values of ＋3.65 to ＋10.05, whole-rock εNd（t） values of -0.09 to ＋2.98 and whole-rock initial ^87Sr/^86Sr ratios of 0.7034-0.7039, indicating that their magma was derived from a juvenile crustal source. Together with geochemical and Hf-Sr-Nd isotopic compositions, it is suggested that the granitoids formed in island-arc setting and originated from partial melting of a subducted oceanic slab. The results support a model that the Yangtze block was surrounded by ocean and arc magmatism in its northern and northwestern margins in Neoproterozoic.
