Porphyry Cu(Mo-Au)deposit is one of the most important types of copper deposit and usually formed under magmatic arc-related settings,whilst the Mujicun porphyry Cu-Mo deposit in North China Craton uncommonly generate...Porphyry Cu(Mo-Au)deposit is one of the most important types of copper deposit and usually formed under magmatic arc-related settings,whilst the Mujicun porphyry Cu-Mo deposit in North China Craton uncommonly generated within intra-continental settings.Although previous studies have focused on the age,origin and ore genesis of the Mujicun deposit,the ore-forming age,magma source and tectonic evolution remain controversial.Here,this study targeted rutile(TiO_(2))in the ore-hosting diorite porphyry from the Mujicun Cu-Mo deposit to conduct in situ U-Pb dating and trace element composition studies,with major views to determine the timing and magma evolution and to provide new insights into porphyry Cu-Mo metallogeny.Rutile trace element data show flat-like REE patterns characterized by relatively enrichment LREEs and depleted HREEs,which could be identified as magmatic rutile.Rutile U-Pb dating yields lower intercept ages of 139.3–138.4 Ma,interpreted as post magmatic cooling timing below about 500℃,which are consistent or slightly postdate with the published zircon U-Pb ages of diorite porphyry(144.1–141.7 Ma)and skarn(146.2 Ma;139.9 Ma)as well as the molybdenite Re-Os ages of molybdenum ores(144.8–140.0 Ma).Given that the overlap between the closure temperature of rutile U-Pb system and ore-forming temperature of the Mujicun deposit,this study suggests that the ore-forming ages of the Mujicun deposit can be constrained at 139.3–138.4 Ma,with temporal links to the late large-scale granitic magmatism at 138–126 Ma in the Taihang Orogen.Based on the Mg and Al contents in rutile,the magma of ore-hosting diorite porphyry was suggested to be derived from crust-mantle mixing components.In conjunction with previous studies in Taihang Orogen,this study proposes that the far-field effect and the rollback of the subducting Paleo-Pacific slab triggered lithospheric extension,asthenosphere upwelling,crust-mantle interaction and thermo-mechanical erosion,which jointly facilitated the formation of dioritic magmas during the Early Cretaceous.Subsequently,the dioritic magmas carrying crust-mantle mixing metallic materials were emplaced and precipitated at shallow positions along NNE-trending ore-controlling faults,eventually resulting in the formation of the Mujicun Cu-Mo deposit within an intracontinental extensional setting.展开更多
Geodynamic mechanism responsible for the generation of Silurian granitoids and the tectonic evolution of the Qilian orogenic belt remains controversial. In this study, we report the results of zircon U–Pb age, and sy...Geodynamic mechanism responsible for the generation of Silurian granitoids and the tectonic evolution of the Qilian orogenic belt remains controversial. In this study, we report the results of zircon U–Pb age, and systematic whole-rock geochemical data for the Haoquangou and Liujiaxia granitoids within the North Qilian orogenic belt and the Qilian Block, respectively, to constrain their petrogenesis, and the Silurian tectonic evolution of the Qilian orogenic belt. Zircon U–Pb ages indicate that the Haoquangou and Liujiaxia intrusions were emplaced at423 ± 3 Ma and 432 ± 4 Ma, respectively. The Haoquangou granodiorites are calc-alkaline, while the Liujiaxia granites belong to the high-K calc-alkaline series.Both are peraluminous in composition and have relatively depleted Nd isotopic [ε_(Nd)(t) =(-3.9 – + 0.6)] characteristics compared with regional basement rocks, implying their derivation from a juvenile lower crust. They show adakitic geochemical characteristics and were generated by partial melting of thickened lower continental crust. Postcollisional extensional regime related to lithospheric delamination was the most likely geodynamic mechanism for the generation of the Haoquangou granodiorite, while the Liujiaxia granites were generated in a compressive setting during continental collision between the Qaidam and Qilian blocks.展开更多
Fossil Taiwania was discovered from the Lower Cretaceous Yixian Formation of Lingyuan City, western Liaoning Province, Northeast China. It is identified as a new species, Taiwania lingyuanensis sp. nov.. The present s...Fossil Taiwania was discovered from the Lower Cretaceous Yixian Formation of Lingyuan City, western Liaoning Province, Northeast China. It is identified as a new species, Taiwania lingyuanensis sp. nov.. The present specimen is preserved as impressions with well defined leaf shoots system and reproductive structures. Leaves are dimorphic, spirally and imbricately arranged. They are scale-like on the main and cone-bearing branchlets, and subulate to falcate-subulate on the juvenile or sterile shoots. The seed cones are singly elliptic, ovate or elongate-ovate and terminally borne on ultimate shoots, bearing 22–24 scale-bracts complexes imbricately and helically arranged around the cone axis, the bracts are broadovate, rhomboidal or hexagonal with entire margins. Both the leafy shoots morphology and reproductive structures are similar to extant Taiwania. Furthermore, geological distribution and molecular biological evidences support that Taiwania is probably originated from the eastern Asia at least in the Early Cretaceous and widely distributed in the North Hemisphere thereafter.展开更多
The Ordos Basin is an important intracontinental sedimentary basin in western China for its abundant Mesozoic crude oil resources. The southern part of the Tianhuan Depression is located in the southwestern marginal a...The Ordos Basin is an important intracontinental sedimentary basin in western China for its abundant Mesozoic crude oil resources. The southern part of the Tianhuan Depression is located in the southwestern marginal area of this Basin, in which the Jurassic and Triassic Chang-3 are the main oil-bearing strata. Currently, no consensus has been reached regarding oil source and oil migration in the area, and an assessment of oil accumulation patterns is thus challenging. In this paper, the oil source, migration direction, charging site and migration pathways are investigated through analysis of pyrrolic nitrogen compounds and hydrocarbon biomarkers. Oil source correlations show that the oils trapped in the Jurassic and Chang-3 reservoirs were derived from the Triassic Chang-7 source rocks. The Jurassic and Chang-3 crude oils both underwent distinct vertical migration from deep to shallow strata, indicating that the oils generated by Chang-7 source rocks may have migrated upward to the shallower Chang-3 and Jurassic strata under abnormally high pressures, to accumulate along the sand bodies of the ancient rivers and the unconformity surface. The charging direction of the Jurassic and Chang-3 crude oils is primarily derived from Mubo, Chenhao, and Shangliyuan, which are located northeast of the southern Tianhuan Depression, with oils moving toward the west, southwest, and south. The results show that an integration of biomarker and nitrogen-bearing compound analyses can provide useful information about oil source, migration, and accumulation.展开更多
Fossil bamboo leaves and pollen from Upper Miocene deposits of the Shengxian Formation in Tiantai and Ninghai counties, eastern Zhejiang, China represent a rare record in Asia. The distinctive pseudopetiole and parall...Fossil bamboo leaves and pollen from Upper Miocene deposits of the Shengxian Formation in Tiantai and Ninghai counties, eastern Zhejiang, China represent a rare record in Asia. The distinctive pseudopetiole and parallel venation of the leaf blades and the clearly thickened annulus of the pollen aperture place them in the subfamily Bambusoideae. Morphological analysis supports the determination of these fossil leaves as belonging to the genus Bambusium and two new species are described. Bambusium latipseudopetiolus Q.J. Wang et B.N. Sun sp. nov. has a distinctly wide pseudopetiole of 0.23 cm in width and 0.40 cm in length, several vascular bundles on parallel veins, and 5-8 lateral veins on both sides of the midrib. Bambusium longipseudopetiolus Q.J. Wang et B.N. Sun sp. nov. has a distinctly long pseudopetiole of 0.60 cm in length and 0.10 cm in width, several vascular bundles on the pseudopetiole, and 6 lateral veins on both sides of the midrib. Pollen grains from the same layer provide additional evidence of bamboos. They are characterized by 32.0-51.0 μm in diameter, a round pore 3.0-4.0 μm in diameter with a broad thickened annulus 2.5-3.5 μm around, and several conspicuous secondary folds on the exine surface. The morphological analysis leads to their assignment to Graminidites bambusoides Stuchlik. These fossils are important for the study of bamboo phytogeography in China. They demonstrate that there were bamboos growing in southeastern China during the Late Miocene and that bamboos in Zhejiang begin to diversify no later than the Late Miocene. In combination with bamboo fossils from other places, it seems that bamboos had a wide distribution across southern China during the Miocene, ranging from southwestern Yun＇nan to southeastern Zhejiang.展开更多
The palaeo-atmospheric CO2 concentration （pCOz） variation in the Yumen, Gansu Province during the middle Cretaceous has been reconstructed using the newly established plant photosynthetic gas exchange mechanistic mo...The palaeo-atmospheric CO2 concentration （pCOz） variation in the Yumen, Gansu Province during the middle Cretaceous has been reconstructed using the newly established plant photosynthetic gas exchange mechanistic model, and the results show that the pCO2 values are in the range of about 550 -808 ppmv. The present pCO2 values are higher than the pCO2 results （531-641 ppmv） of the previous study according to the Recent standardization of the stomatal ratio method, and much lower than the pCO2 results （882-1060 ppmv） according to the Carboniferous standardization of the stomatal ratio method. The present pCOz variation is not only within the error range of GEOCARB II and GEOCARB Ill but also is similar to the reconstructed results based on the biochemistry and carbon isotope models. Besides, the present Brachyphyllum specimens were collected from four consecutive horizons of the upper Zhonggou Formation of the Hanxia Section, and the reconstructed pCO2 exhibits the reconstructed pCO2 exhibits a decline trend during the late Aptian to early Albian. This decline variation is probably associated with the Oceanic Anoxic Events （OAElb） and the Cold snap event. With the combination of pCO2 during the Albian to Cenomanian recovered by the plant photosynthetic gas exchange mechanistic model, the pCO2 showed a prominent increase during the late Aptian to early Cenominian, which indicates a response to the greenhouse warming during the middle Cretaceous. Therefore, the mechanical model of the plant photosynthetic gas exchange shows a relatively strong accuracy in the reconstruction of thepCO2 and can reflect a strong relation between the atmospheric CO2 concentrations and climatic events.展开更多
The present paper reports two new species of Buxus from the Oligocene Ningming Formation of Guangxi, South China, on the basis of several compressed fossil leaves.Buxus ningmingensis sp.nov.is characterized by an elli...The present paper reports two new species of Buxus from the Oligocene Ningming Formation of Guangxi, South China, on the basis of several compressed fossil leaves.Buxus ningmingensis sp.nov.is characterized by an elliptic to ovate shape; pinnate venation with marginal secondary, long hairs on the adaxial side of the midvein base; and amphistomatic, anomocytic stomata with a prominent outer ring.All of these characteristics suggest a closest affinity to the living Buxus microphylla subsp.sinica.Another new species identified as Buxus preaustro-yunnanensis sp.nov.is characterized by the diagnostic formation of its admedially branched tertiaries, the trunks of which are often strongly thickened by sclereides.This species is most similar to the extant Buxus austroyunnanensis.The co-occurrence of Buxus ningmingensis sp.nov.and Buxus preaustro-yunnanensis sp.nov.suggests that these two Buxus lived during the Oligocene under a warm, tropical to subtropical climate, similar to the current climate of Ningming.Our findings provide the earliest fossil evidence of Buxus leaves with detailed illustrations of leaf architectural and cuticular features.The occurrence of these two species indicates that Buxus began to diversify in Guangxi no later than the Oligocene.展开更多
The Ordovician(485.4 Ma-443.8Ma)is the longest period of the Paleozoic,which was characterized by a peak of greenhouse climate in Earth history,as well as extreme high sea level(Haq and Schutter,2008;Munnecke et al.,2...The Ordovician(485.4 Ma-443.8Ma)is the longest period of the Paleozoic,which was characterized by a peak of greenhouse climate in Earth history,as well as extreme high sea level(Haq and Schutter,2008;Munnecke et al.,2010),with warm and humid conditions in early-middle period and seawater temperature up to 45℃(Trotter et al.,2008).展开更多
Cupressinocladus Seward is a fossil genus of conifers and conifer fossils with reproductive organs are very rare. In general, it is difficult to understand the natural affinities with other conifers. In this paper, a ...Cupressinocladus Seward is a fossil genus of conifers and conifer fossils with reproductive organs are very rare. In general, it is difficult to understand the natural affinities with other conifers. In this paper, a new species, Cupressinocladus guyangensis P.H. Jin et B.N. Sun sp. nov., is reported based on branches with immature female cones from the Lower Cretaceous Guyang Formation of the Guyang Basin in Inner Mongolia, northern China. The foliage shoots are decussate. Leaves are decussate, imbricate, scale-like, weakly dimorphic, and bear longitudinal glands on the abaxial view. Stomata complexes are haplocheilic, monocyclic, irregularly arranged, and spread along the leaf margin. Immature female cones are subglobose with 6-8 cone scales, and three subglobose ovules arranged in a row at the base of the cone scales. Moreover, we performed cluster analysis using a statistics and machine learning toolbox for 23 fossils and extant species based on 16 morphological characters. The result implies that the new species bears a close resemblance to the extant Cupressusfunebris Endl. and might have nearest systematic affinities to it.展开更多
In Europe, fossil fruits and seeds of Rhodoleia（Hamamelidaceae） have been described from the Upper Cretaceous to the Miocene, whereas no fossil record of Rhodoleia has been reported in Asia, where the modern species...In Europe, fossil fruits and seeds of Rhodoleia（Hamamelidaceae） have been described from the Upper Cretaceous to the Miocene, whereas no fossil record of Rhodoleia has been reported in Asia, where the modern species occur.Herein, 21 fossil leaves identified as Rhodoleia tengchongensis sp.nov.are described from the Upper Pliocene of Tengchong County, Yunnan Province, Southwest China.The fossils exhibit elliptic lamina with entire margins, simple brochidodromous major secondary veins, mixed percurrent intercostal tertiary veins, and looped exterior tertiaries.The leaf cuticle is characterized by pentagonal or hexagonal cells, stellate multicellular trichomes, and paracytic stomata.The combination of leaf architecture and cuticular characteristics suggests that the fossil leaves should be classified into the genus Rhodoleia.The fossil distributions indicate that the genus Rhodoleia might originate from Central Europe, and that migrated to Asia prior to the Late Pliocene.Additionally, insect damage is investigated, and different types of damage, such as hole feeding, margin feeding, surface feeding, and galling, are observed on the thirteen fossil leaves.Based on the damage frequencies for the fossil and extant leaves, the specific feeding behavior of insects on Rhodoleia trees appears to have been established as early as the Late Pliocene.The high occurrence of Rhodoleia insect herbivory may attract the insect-foraging birds, thereby increasing the probability of pollination.展开更多
Well-preserved Ginkgo pollen organs are analyzed from the Middle Jurassic Xishanyao Formation of the Turpan–Hami Basin, Xinjiang Uygur Autonomous Region, northwestern China, and are described as a new species, Ginkgo...Well-preserved Ginkgo pollen organs are analyzed from the Middle Jurassic Xishanyao Formation of the Turpan–Hami Basin, Xinjiang Uygur Autonomous Region, northwestern China, and are described as a new species, Ginkgo hamiensis Z.X. Wang et B.N. Sun sp. nov. The immature male cones are cylindrical and catkin-like, with two longitudinal stripes on the stalk. The pollen sacs are shaped like a long oval with two pollen sacs fused together for each microsporophyll, and the microsporophyll tip is a triangular cystidium. The pollen grains are oblong or fusiform and monocolpate; both ends are blunt or sharp. By comparison with previously reported fossil records of Ginkgo plants, we determined that the current fossils are different from all other reported species; thus, the present fossil is referred to as a new species of Ginkgo. The reproductive organs of the Ginkgo fossils described herein can provide valuable information for the study of Ginkgo plants. Further, there are two probable evolutionary trends in the Ginkgo pollen cones. One trend is that the number of pollen sacs changed from three or four during the Jurassic and Cretaceous to two at the present day; the other is that the number of pollen sacs has remained two from the Middle Jurassic to the present day. In addition, the pollen cones described herein are similar to the pollen cones of the extant Ginkgo, which strongly indicates that the morphology of Ginkgo plants may have remained highly conserved over millions of years.展开更多
Albizzia is a leguminous genus belonging to the subfamily Mimosoideae with approximately 150 modern species, widely distributed in the tropical and subtropical regions of Asia, Africa, Australia and America. Among the...Albizzia is a leguminous genus belonging to the subfamily Mimosoideae with approximately 150 modern species, widely distributed in the tropical and subtropical regions of Asia, Africa, Australia and America. Among them, 17 species are mainly distributed in southern and southwestern China. Abundant fossils of the subfamily Mimosoideae, including leaves, pods, flowers and wood, have been reported from the Cretaceous and Paleogene strata of the Northern Hemisphere. However, Neogene records of Mimosoideae are relatively scarce. In this study, fossil pods and leaves belonging to the genus Aibizzia from the Bangmai Formation of Yunnan, China were described. They were assigned to three species, including Albizzia scalpeUiformis Guo, Li and Xie Emended, Albizzia cf. kalkora （Roxb.） Prain and Albizzia sp. The occurrence of Albizzia fossils from Lincang not only gives important information on the Neogene plant diversity from Yunnan--a worldwide famous biological hotspot--but also provides additional evidence for its phytogeographic history.展开更多
Sedimentary chert phases from the Archean to the present are widely used to trace sedimentary environments and tectonic settings.Recently,chert nodules occurring within carbonates have been the subject of possible hyd...Sedimentary chert phases from the Archean to the present are widely used to trace sedimentary environments and tectonic settings.Recently,chert nodules occurring within carbonates have been the subject of possible hydrothermal or biogenic origin,in lieu of a diagenetic origin.However,chert nodules from a vast cratonic basin represent extremely rich silica accumulations but less noted is how they respond to submarine hydrothermal activity(and/or surface siliceous organism productivity).The links between the cratonic-type chert depositions and environmental changes regarding cratonic evolution need to be revisited at a large temporal-spatial scale.The chert nodules are widespread throughout the Lower Permian Taiyuan Formation in the North China Craton(NCC).Several Taiyuan chert-rich successions across the NCC have been selected to study possible links between chert deposition and cratonic evolution in scenario of partial cratonic activation of the northern NCC margin during the Late Paleozoic.Based on stratigraphic correlation,the chert nodules are ubiquitously,evenly distributed throughout the Taiyuan Formation at a large craton-basin scale from the northern to southern interior NCC.Petrological results,elemental abundances,together with silicon and oxygen isotopic compositions of chert samples infer significant hydrothermal contributions for the silica accumulations.Therefore,the cratonic-scale chert depositions of hydrothermal origin infer a giant and remote silica reservoir,linking to the large igneous province and magmatism in the NCC northern margins.The Taiyuan chert nodules could be unique marine sedimentary archives recording the Late Paleozoic NCC partial activation,which also generated continental records of igneous rocks,bauxites and tuffs.The strong tectonics of the northern margin,south-dipping topography and northward transgression of the Early Permian NCC facilitated the chert deposition on the shallow marine platform in the cratonic interior.展开更多
The natural remnant magnetization(NRM)of carbonate rocks in particular must be understood for the construction of a meaningful Paleozoic geomagnetic polarity time scale.This would enable evaluating geomagnetic feature...The natural remnant magnetization(NRM)of carbonate rocks in particular must be understood for the construction of a meaningful Paleozoic geomagnetic polarity time scale.This would enable evaluating geomagnetic features(e.g.reversal frequency)and would provide a paleomagnetic dating tool(Voo,1990).展开更多
Lindera is a large genus of graceful, pleasantly scented and common native trees and shrubs of southern China and neighboring regions of SE Asia. There is a well-documented Cenozoic fossil record not only in these reg...Lindera is a large genus of graceful, pleasantly scented and common native trees and shrubs of southern China and neighboring regions of SE Asia. There is a well-documented Cenozoic fossil record not only in these regions but also from elsewhere. A new fossil leaf record has been found in diatomite beds from the Upper Pliocene Mangbang Formation of Tuantian, Tengchong County, Yunnan. The leaves are identified and assigned to Lindera acuminatissima K. Q. Dao et B. N. Sun sp. nov., by comparing their leaf architecture and epidermal characteristics with those of 51 extant Lauraceae species and with 15 known fossil Lindera taxa. The specimens have well-preserved cuticles, with typical leaf architecture and epidermal characteristics of the Lanraceae, including entire leaf margin, intramarginal veins, basal ternate acrodromous primary veins, one-cell trichome base, paracytic stomatal apparatus, sunken guard cells, subsidiary hardly staining cells and presence of oil cells. These characteristics are consistent with Lindera sect. Daphnidium but are different from reported fossil and extant species of Lindera. The cuticles of Lindera are fragile and delicate with only three Lindera fossils reported based on this tissue. In terms of paleobiogeography, the fossil record indicates that Lindera is distributed in high- to mid-latitude regions of the Late Cretaceous to Paleocene northern hemisphere. Coincidentally, the records of Lindera located on both sides of the Bering Land Bridge possibly support the hypothesis that ancient plants extended via transcontinental exchanges through the Bering Corridor. In the Eocene, ancient Lindera spread to Europe through the Northern Degeer Route and the Southern Thulian Route. At the same time, ancient Lindera spread into Central Asia. Climatic changes and tectonization since the Neogene prevented the propagation of Lindera throughout Asia, North America and Europe, and hence the distribution areas have just regressed to the low-latitude regions in Asia and North America. From the Paleogene to the Neogene, Lindera has changed its distribution by surviving extreme climate changes. Quaternary glaciations ultimately led to Lindera becoming extinct in Europe. The new record from Tengchong, Yunnan, with its lower latitude located in tropical and subtropical regions, indicates that Lindera has lived in those regions since the late Pliocene.展开更多
Objective Large numbers of archeological relics from the Neolithic period are widely distributed in all tributaries of the Yellow River. The early humans tended to reside along the river valleys, and developed small b...Objective Large numbers of archeological relics from the Neolithic period are widely distributed in all tributaries of the Yellow River. The early humans tended to reside along the river valleys, and developed small but characteristically decentralized ancient valley culture. It is universally acknowledged that the agriculture exchange between China and western countries and the moderate展开更多
The central and northwestern Tibetan Plateau region,also called＂Qiangtang Plateau＂（30°27＇25＂-35°39＇13＂N,83o41＇14＂-95°10＇46＂E）,is the highest and largest arcticalpine area of the Earth coveri...The central and northwestern Tibetan Plateau region,also called＂Qiangtang Plateau＂（30°27＇25＂-35°39＇13＂N,83o41＇14＂-95°10＇46＂E）,is the highest and largest arcticalpine area of the Earth covering approximately 600,000km^2 with altitude ranging from 4600 to 5100 m a.s.l.（Song et al.,2012,Fig.1）.展开更多
The Qaidam Basin,as the largest inland basin within the Tibetan Plateau,has accumulated more than 10,000 m of Cenozoic continental sediments.It serves as a crucial research area for documenting Cenozoic climate change...The Qaidam Basin,as the largest inland basin within the Tibetan Plateau,has accumulated more than 10,000 m of Cenozoic continental sediments.It serves as a crucial research area for documenting Cenozoic climate changes and plateau uplift processes in the Asian interior.Additionally,the basin holds vast reserves of oil and gas resources,making high-resolution drilling data invaluable for studying paleoclimate.In this study,the longsequence lacustrine deposits of JS1 drill core across the Shizigou Formation in the Yiliping Depression at the western center of the basin were studied,aiming to establish an astronomical timescale for the Shizigou Formation and investigate the characteristics of paleoclimatic changes during the late Miocene to the Pliocene for the Asian interior.The analysis was carried out using high-resolution natural gamma ray(GR)data sequences,employing techniques such as spectral analysis,filtering,and wavelet analysis in cyclostratigraphy.The results indicated the presence of a stable Milankovitch orbital signal was perfectly recorded in the Shizigou Formation,primarily influenced by eccentricity cycles,with weaker obliquity and precession cycles.Using the stable and continuous 405 ka eccentricity cycle in astronomical tuning,a"floating"astronomical timescale with a duration of 6.1 Ma for the Yiliping depression's Shizigou Formation has been established.With reference to previously established stratigraphic age anchor points,an absolute astronomical timescale(2.5–8.6 Ma)has been ultimately provided for the Shizigou Formation.Simultaneously,a clear 100 ka short eccentricity cycle record has been identified during the Pliocene(5.3–2.5 Ma),which corresponds in time with the aridification within the basin during this Pliocene period.In addition,a comparison of the Pliocene natural gamma ray curve of the Qaidam Basin with global ice volume variations indicated that the basin's aridification was influenced by global cooling,with eccentricity-modulated precession cycles controlling solar radiation and subsequently affecting the evolution of lakes in the arid region of Inner Asia.展开更多
The geodynamic processes for the Neoproterozoic mafic-ultramafic intrusions and dykes in the Kuluketage region,Tarim Craton has also been debated for some time.Some researchers suggested that the Neoproterozoic
Objective The lake levels in the eastern and southern Asia are regarded as low lake-level owing to precipitation decreasing based on the records of lake-level fluctuation in the continental interior lakes since the la...Objective The lake levels in the eastern and southern Asia are regarded as low lake-level owing to precipitation decreasing based on the records of lake-level fluctuation in the continental interior lakes since the last glacial maximum（LGM）（14C 18±1 kaBP,since 20 kaBP）in the Central Asia.Higher lake-level appeared in the transition belt between western Kunlun Mountain and the central Tibetan Plateau.展开更多
基金jointly supported by the National Natural Science Foundation of China(4220207742103025)+5 种基金the Opening Foundation of MNR Key Laboratory of Metallogeny and Mineral Assessment(ZS2209ZS2106)the Opening Foundation of Key Laboratory of Mineral Resources in Western China(Gansu Province)(MRWCGS-2021-01)the Natural Science Foundation of Gansu Province(22JR5RA440)the Fundamental Research Funds for the Central Universities(LZUJBKY-2022-42)the Guiding Special Funds of“Double First-Class(First-Class University&First-Class Disciplines)”(561119201)of Lanzhou University,China。
文摘Porphyry Cu(Mo-Au)deposit is one of the most important types of copper deposit and usually formed under magmatic arc-related settings,whilst the Mujicun porphyry Cu-Mo deposit in North China Craton uncommonly generated within intra-continental settings.Although previous studies have focused on the age,origin and ore genesis of the Mujicun deposit,the ore-forming age,magma source and tectonic evolution remain controversial.Here,this study targeted rutile(TiO_(2))in the ore-hosting diorite porphyry from the Mujicun Cu-Mo deposit to conduct in situ U-Pb dating and trace element composition studies,with major views to determine the timing and magma evolution and to provide new insights into porphyry Cu-Mo metallogeny.Rutile trace element data show flat-like REE patterns characterized by relatively enrichment LREEs and depleted HREEs,which could be identified as magmatic rutile.Rutile U-Pb dating yields lower intercept ages of 139.3–138.4 Ma,interpreted as post magmatic cooling timing below about 500℃,which are consistent or slightly postdate with the published zircon U-Pb ages of diorite porphyry(144.1–141.7 Ma)and skarn(146.2 Ma;139.9 Ma)as well as the molybdenite Re-Os ages of molybdenum ores(144.8–140.0 Ma).Given that the overlap between the closure temperature of rutile U-Pb system and ore-forming temperature of the Mujicun deposit,this study suggests that the ore-forming ages of the Mujicun deposit can be constrained at 139.3–138.4 Ma,with temporal links to the late large-scale granitic magmatism at 138–126 Ma in the Taihang Orogen.Based on the Mg and Al contents in rutile,the magma of ore-hosting diorite porphyry was suggested to be derived from crust-mantle mixing components.In conjunction with previous studies in Taihang Orogen,this study proposes that the far-field effect and the rollback of the subducting Paleo-Pacific slab triggered lithospheric extension,asthenosphere upwelling,crust-mantle interaction and thermo-mechanical erosion,which jointly facilitated the formation of dioritic magmas during the Early Cretaceous.Subsequently,the dioritic magmas carrying crust-mantle mixing metallic materials were emplaced and precipitated at shallow positions along NNE-trending ore-controlling faults,eventually resulting in the formation of the Mujicun Cu-Mo deposit within an intracontinental extensional setting.
基金funded by Gansu Provincial Natural Science Foundation (Grant Numbers 21JR7RA503 and22JR5RA819)the Fundamental Research Funds for the Central Universities (Grant lzujbky-2021-ct07)+1 种基金the Key Talent Project of Gansu Province (2022-Yangzhenxi)the National Second Expedition to the Tibetan Plateau (2019QZKK0704)。
文摘Geodynamic mechanism responsible for the generation of Silurian granitoids and the tectonic evolution of the Qilian orogenic belt remains controversial. In this study, we report the results of zircon U–Pb age, and systematic whole-rock geochemical data for the Haoquangou and Liujiaxia granitoids within the North Qilian orogenic belt and the Qilian Block, respectively, to constrain their petrogenesis, and the Silurian tectonic evolution of the Qilian orogenic belt. Zircon U–Pb ages indicate that the Haoquangou and Liujiaxia intrusions were emplaced at423 ± 3 Ma and 432 ± 4 Ma, respectively. The Haoquangou granodiorites are calc-alkaline, while the Liujiaxia granites belong to the high-K calc-alkaline series.Both are peraluminous in composition and have relatively depleted Nd isotopic [ε_(Nd)(t) =(-3.9 – + 0.6)] characteristics compared with regional basement rocks, implying their derivation from a juvenile lower crust. They show adakitic geochemical characteristics and were generated by partial melting of thickened lower continental crust. Postcollisional extensional regime related to lithospheric delamination was the most likely geodynamic mechanism for the generation of the Haoquangou granodiorite, while the Liujiaxia granites were generated in a compressive setting during continental collision between the Qaidam and Qilian blocks.
基金conducted under the 973 Program of China (No. 2012CB822003)the National Natural Science Foundation of China (Nos. 41402007, 41602023)the Fundamental Research Funds for the Central Universities (Lzujbky-2014-132)
文摘Fossil Taiwania was discovered from the Lower Cretaceous Yixian Formation of Lingyuan City, western Liaoning Province, Northeast China. It is identified as a new species, Taiwania lingyuanensis sp. nov.. The present specimen is preserved as impressions with well defined leaf shoots system and reproductive structures. Leaves are dimorphic, spirally and imbricately arranged. They are scale-like on the main and cone-bearing branchlets, and subulate to falcate-subulate on the juvenile or sterile shoots. The seed cones are singly elliptic, ovate or elongate-ovate and terminally borne on ultimate shoots, bearing 22–24 scale-bracts complexes imbricately and helically arranged around the cone axis, the bracts are broadovate, rhomboidal or hexagonal with entire margins. Both the leafy shoots morphology and reproductive structures are similar to extant Taiwania. Furthermore, geological distribution and molecular biological evidences support that Taiwania is probably originated from the eastern Asia at least in the Early Cretaceous and widely distributed in the North Hemisphere thereafter.
基金supported by the National Basic Research Program of China (973 Program) (No. 2012CB822003)Specialized Research Fund for the Doctoral Program of Higher Education (No. 20120211110022)the National Science and Technology Major Projects (2011zx05001-004)
文摘The Ordos Basin is an important intracontinental sedimentary basin in western China for its abundant Mesozoic crude oil resources. The southern part of the Tianhuan Depression is located in the southwestern marginal area of this Basin, in which the Jurassic and Triassic Chang-3 are the main oil-bearing strata. Currently, no consensus has been reached regarding oil source and oil migration in the area, and an assessment of oil accumulation patterns is thus challenging. In this paper, the oil source, migration direction, charging site and migration pathways are investigated through analysis of pyrrolic nitrogen compounds and hydrocarbon biomarkers. Oil source correlations show that the oils trapped in the Jurassic and Chang-3 reservoirs were derived from the Triassic Chang-7 source rocks. The Jurassic and Chang-3 crude oils both underwent distinct vertical migration from deep to shallow strata, indicating that the oils generated by Chang-7 source rocks may have migrated upward to the shallower Chang-3 and Jurassic strata under abnormally high pressures, to accumulate along the sand bodies of the ancient rivers and the unconformity surface. The charging direction of the Jurassic and Chang-3 crude oils is primarily derived from Mubo, Chenhao, and Shangliyuan, which are located northeast of the southern Tianhuan Depression, with oils moving toward the west, southwest, and south. The results show that an integration of biomarker and nitrogen-bearing compound analyses can provide useful information about oil source, migration, and accumulation.
基金conducted under the National Natural Science Foundation of China(No.41172022)Specialized Research Fund for the Doctoral Program of Higher Education(Grant No.20120211110022,20100211110019)the Fundamental Research Funds for the Central Universities(No.lzujbky2014-285)
文摘Fossil bamboo leaves and pollen from Upper Miocene deposits of the Shengxian Formation in Tiantai and Ninghai counties, eastern Zhejiang, China represent a rare record in Asia. The distinctive pseudopetiole and parallel venation of the leaf blades and the clearly thickened annulus of the pollen aperture place them in the subfamily Bambusoideae. Morphological analysis supports the determination of these fossil leaves as belonging to the genus Bambusium and two new species are described. Bambusium latipseudopetiolus Q.J. Wang et B.N. Sun sp. nov. has a distinctly wide pseudopetiole of 0.23 cm in width and 0.40 cm in length, several vascular bundles on parallel veins, and 5-8 lateral veins on both sides of the midrib. Bambusium longipseudopetiolus Q.J. Wang et B.N. Sun sp. nov. has a distinctly long pseudopetiole of 0.60 cm in length and 0.10 cm in width, several vascular bundles on the pseudopetiole, and 6 lateral veins on both sides of the midrib. Pollen grains from the same layer provide additional evidence of bamboos. They are characterized by 32.0-51.0 μm in diameter, a round pore 3.0-4.0 μm in diameter with a broad thickened annulus 2.5-3.5 μm around, and several conspicuous secondary folds on the exine surface. The morphological analysis leads to their assignment to Graminidites bambusoides Stuchlik. These fossils are important for the study of bamboo phytogeography in China. They demonstrate that there were bamboos growing in southeastern China during the Late Miocene and that bamboos in Zhejiang begin to diversify no later than the Late Miocene. In combination with bamboo fossils from other places, it seems that bamboos had a wide distribution across southern China during the Miocene, ranging from southwestern Yun＇nan to southeastern Zhejiang.
基金the National Natural Science Foundation of China(No.41402007,41602023,40972025)the State Key Laboratory of Palaeobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology,CAS(No.153102)
文摘The palaeo-atmospheric CO2 concentration （pCOz） variation in the Yumen, Gansu Province during the middle Cretaceous has been reconstructed using the newly established plant photosynthetic gas exchange mechanistic model, and the results show that the pCO2 values are in the range of about 550 -808 ppmv. The present pCO2 values are higher than the pCO2 results （531-641 ppmv） of the previous study according to the Recent standardization of the stomatal ratio method, and much lower than the pCO2 results （882-1060 ppmv） according to the Carboniferous standardization of the stomatal ratio method. The present pCOz variation is not only within the error range of GEOCARB II and GEOCARB Ill but also is similar to the reconstructed results based on the biochemistry and carbon isotope models. Besides, the present Brachyphyllum specimens were collected from four consecutive horizons of the upper Zhonggou Formation of the Hanxia Section, and the reconstructed pCO2 exhibits the reconstructed pCO2 exhibits a decline trend during the late Aptian to early Albian. This decline variation is probably associated with the Oceanic Anoxic Events （OAElb） and the Cold snap event. With the combination of pCO2 during the Albian to Cenomanian recovered by the plant photosynthetic gas exchange mechanistic model, the pCO2 showed a prominent increase during the late Aptian to early Cenominian, which indicates a response to the greenhouse warming during the middle Cretaceous. Therefore, the mechanical model of the plant photosynthetic gas exchange shows a relatively strong accuracy in the reconstruction of thepCO2 and can reflect a strong relation between the atmospheric CO2 concentrations and climatic events.
基金financially supported by the National Basic Research Program of China (973 Program) (No.2012CB822003)the Funds of Key Laboratory of Petroleum Resources, Gansu Province (No.SZDKFJJ20150603)+2 种基金the National Natural Science Foundation of China (Nos.41172022, 41272026)the Funds of Key Laboratory of Economic Stratigraphy and Palaeogeography, Nanjing Institute of Geology and Palaeontology, CAS (No.Y421140303)the Fundamental Research Funds for the Central Universities (No.lzujbky-2014-285)
文摘The present paper reports two new species of Buxus from the Oligocene Ningming Formation of Guangxi, South China, on the basis of several compressed fossil leaves.Buxus ningmingensis sp.nov.is characterized by an elliptic to ovate shape; pinnate venation with marginal secondary, long hairs on the adaxial side of the midvein base; and amphistomatic, anomocytic stomata with a prominent outer ring.All of these characteristics suggest a closest affinity to the living Buxus microphylla subsp.sinica.Another new species identified as Buxus preaustro-yunnanensis sp.nov.is characterized by the diagnostic formation of its admedially branched tertiaries, the trunks of which are often strongly thickened by sclereides.This species is most similar to the extant Buxus austroyunnanensis.The co-occurrence of Buxus ningmingensis sp.nov.and Buxus preaustro-yunnanensis sp.nov.suggests that these two Buxus lived during the Oligocene under a warm, tropical to subtropical climate, similar to the current climate of Ningming.Our findings provide the earliest fossil evidence of Buxus leaves with detailed illustrations of leaf architectural and cuticular features.The occurrence of these two species indicates that Buxus began to diversify in Guangxi no later than the Oligocene.
基金supported by the Fundamental Research Funds for the Central Universities(Grant No.lzujbky-2017-k27)contributed to IGCP 652.
文摘The Ordovician(485.4 Ma-443.8Ma)is the longest period of the Paleozoic,which was characterized by a peak of greenhouse climate in Earth history,as well as extreme high sea level(Haq and Schutter,2008;Munnecke et al.,2010),with warm and humid conditions in early-middle period and seawater temperature up to 45℃(Trotter et al.,2008).
基金financially supported by the National Basic Research Program of China(973 Program)(No. 2012CB822003)the Specialized Research Fund for the Doctoral Program of Higher Education(No. 20120211110022)+2 种基金the National Natural Science Foundation of China(No.41402007)the Fundamental Research Funds for the Central Universities(No.lzujbky2016-201)the US Louisiana Board of Regents under grant LEQSF(2017-20)-RD-A-29
文摘Cupressinocladus Seward is a fossil genus of conifers and conifer fossils with reproductive organs are very rare. In general, it is difficult to understand the natural affinities with other conifers. In this paper, a new species, Cupressinocladus guyangensis P.H. Jin et B.N. Sun sp. nov., is reported based on branches with immature female cones from the Lower Cretaceous Guyang Formation of the Guyang Basin in Inner Mongolia, northern China. The foliage shoots are decussate. Leaves are decussate, imbricate, scale-like, weakly dimorphic, and bear longitudinal glands on the abaxial view. Stomata complexes are haplocheilic, monocyclic, irregularly arranged, and spread along the leaf margin. Immature female cones are subglobose with 6-8 cone scales, and three subglobose ovules arranged in a row at the base of the cone scales. Moreover, we performed cluster analysis using a statistics and machine learning toolbox for 23 fossils and extant species based on 16 morphological characters. The result implies that the new species bears a close resemblance to the extant Cupressusfunebris Endl. and might have nearest systematic affinities to it.
基金granted by the National Natural Science Foundation of China (Nos.41302009, 41402008, 41172022 and 41172021)the Foundation of the State Key Laboratory of Paleobiology and Stratigraphy, Nanjing Institute of Geology and Paleontology, CAS (No.133102)the NSF EAR-0746105 to YSL
文摘In Europe, fossil fruits and seeds of Rhodoleia（Hamamelidaceae） have been described from the Upper Cretaceous to the Miocene, whereas no fossil record of Rhodoleia has been reported in Asia, where the modern species occur.Herein, 21 fossil leaves identified as Rhodoleia tengchongensis sp.nov.are described from the Upper Pliocene of Tengchong County, Yunnan Province, Southwest China.The fossils exhibit elliptic lamina with entire margins, simple brochidodromous major secondary veins, mixed percurrent intercostal tertiary veins, and looped exterior tertiaries.The leaf cuticle is characterized by pentagonal or hexagonal cells, stellate multicellular trichomes, and paracytic stomata.The combination of leaf architecture and cuticular characteristics suggests that the fossil leaves should be classified into the genus Rhodoleia.The fossil distributions indicate that the genus Rhodoleia might originate from Central Europe, and that migrated to Asia prior to the Late Pliocene.Additionally, insect damage is investigated, and different types of damage, such as hole feeding, margin feeding, surface feeding, and galling, are observed on the thirteen fossil leaves.Based on the damage frequencies for the fossil and extant leaves, the specific feeding behavior of insects on Rhodoleia trees appears to have been established as early as the Late Pliocene.The high occurrence of Rhodoleia insect herbivory may attract the insect-foraging birds, thereby increasing the probability of pollination.
基金conducted under the National Natural Science Foundation of China (No.41172022)the Funds of Key Laboratory of Petroleum Resources,Gansu Province (No.SZD-KFJJ20150603)the Fundamental Research Funds for the Central Universities (No.lzujbky-2016-202)
文摘Well-preserved Ginkgo pollen organs are analyzed from the Middle Jurassic Xishanyao Formation of the Turpan–Hami Basin, Xinjiang Uygur Autonomous Region, northwestern China, and are described as a new species, Ginkgo hamiensis Z.X. Wang et B.N. Sun sp. nov. The immature male cones are cylindrical and catkin-like, with two longitudinal stripes on the stalk. The pollen sacs are shaped like a long oval with two pollen sacs fused together for each microsporophyll, and the microsporophyll tip is a triangular cystidium. The pollen grains are oblong or fusiform and monocolpate; both ends are blunt or sharp. By comparison with previously reported fossil records of Ginkgo plants, we determined that the current fossils are different from all other reported species; thus, the present fossil is referred to as a new species of Ginkgo. The reproductive organs of the Ginkgo fossils described herein can provide valuable information for the study of Ginkgo plants. Further, there are two probable evolutionary trends in the Ginkgo pollen cones. One trend is that the number of pollen sacs changed from three or four during the Jurassic and Cretaceous to two at the present day; the other is that the number of pollen sacs has remained two from the Middle Jurassic to the present day. In addition, the pollen cones described herein are similar to the pollen cones of the extant Ginkgo, which strongly indicates that the morphology of Ginkgo plants may have remained highly conserved over millions of years.
基金supported by the National Natural Science Foundation of China(Nos.41172021,41302009)the Foundation of the State Key Laboratory of Palaeobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology,CAS(No.173126)the Fundamental Research Funds for the Central Universities of China(No.lzujbky-2017-74)
文摘Albizzia is a leguminous genus belonging to the subfamily Mimosoideae with approximately 150 modern species, widely distributed in the tropical and subtropical regions of Asia, Africa, Australia and America. Among them, 17 species are mainly distributed in southern and southwestern China. Abundant fossils of the subfamily Mimosoideae, including leaves, pods, flowers and wood, have been reported from the Cretaceous and Paleogene strata of the Northern Hemisphere. However, Neogene records of Mimosoideae are relatively scarce. In this study, fossil pods and leaves belonging to the genus Aibizzia from the Bangmai Formation of Yunnan, China were described. They were assigned to three species, including Albizzia scalpeUiformis Guo, Li and Xie Emended, Albizzia cf. kalkora （Roxb.） Prain and Albizzia sp. The occurrence of Albizzia fossils from Lincang not only gives important information on the Neogene plant diversity from Yunnan--a worldwide famous biological hotspot--but also provides additional evidence for its phytogeographic history.
基金supported by the National Natural Science Foundation of China(Grant nos.41702029,41703018,4012123)the Fundamental Research Funds for the Central Universities(Grant No.lzujbky-2017-5)the Second Tibetan Plateau Scientific Expedition(STEP)program(Grant No.2019QZKK0704)。
文摘Sedimentary chert phases from the Archean to the present are widely used to trace sedimentary environments and tectonic settings.Recently,chert nodules occurring within carbonates have been the subject of possible hydrothermal or biogenic origin,in lieu of a diagenetic origin.However,chert nodules from a vast cratonic basin represent extremely rich silica accumulations but less noted is how they respond to submarine hydrothermal activity(and/or surface siliceous organism productivity).The links between the cratonic-type chert depositions and environmental changes regarding cratonic evolution need to be revisited at a large temporal-spatial scale.The chert nodules are widespread throughout the Lower Permian Taiyuan Formation in the North China Craton(NCC).Several Taiyuan chert-rich successions across the NCC have been selected to study possible links between chert deposition and cratonic evolution in scenario of partial cratonic activation of the northern NCC margin during the Late Paleozoic.Based on stratigraphic correlation,the chert nodules are ubiquitously,evenly distributed throughout the Taiyuan Formation at a large craton-basin scale from the northern to southern interior NCC.Petrological results,elemental abundances,together with silicon and oxygen isotopic compositions of chert samples infer significant hydrothermal contributions for the silica accumulations.Therefore,the cratonic-scale chert depositions of hydrothermal origin infer a giant and remote silica reservoir,linking to the large igneous province and magmatism in the NCC northern margins.The Taiyuan chert nodules could be unique marine sedimentary archives recording the Late Paleozoic NCC partial activation,which also generated continental records of igneous rocks,bauxites and tuffs.The strong tectonics of the northern margin,south-dipping topography and northward transgression of the Early Permian NCC facilitated the chert deposition on the shallow marine platform in the cratonic interior.
基金funded by the fundamental research funds for the Central Universities(Grant No.lzujbky-2017-k27)IGCP652.
文摘The natural remnant magnetization(NRM)of carbonate rocks in particular must be understood for the construction of a meaningful Paleozoic geomagnetic polarity time scale.This would enable evaluating geomagnetic features(e.g.reversal frequency)and would provide a paleomagnetic dating tool(Voo,1990).
基金conducted under the National Basic Research Program of China (973: No. 2012CB822000)the National Natural Science Foundation of China (Nos. 41172022 and 41172021)the Fundamental Research Funds for the Central Universities (No. lzujbky-2012-127)
文摘Lindera is a large genus of graceful, pleasantly scented and common native trees and shrubs of southern China and neighboring regions of SE Asia. There is a well-documented Cenozoic fossil record not only in these regions but also from elsewhere. A new fossil leaf record has been found in diatomite beds from the Upper Pliocene Mangbang Formation of Tuantian, Tengchong County, Yunnan. The leaves are identified and assigned to Lindera acuminatissima K. Q. Dao et B. N. Sun sp. nov., by comparing their leaf architecture and epidermal characteristics with those of 51 extant Lauraceae species and with 15 known fossil Lindera taxa. The specimens have well-preserved cuticles, with typical leaf architecture and epidermal characteristics of the Lanraceae, including entire leaf margin, intramarginal veins, basal ternate acrodromous primary veins, one-cell trichome base, paracytic stomatal apparatus, sunken guard cells, subsidiary hardly staining cells and presence of oil cells. These characteristics are consistent with Lindera sect. Daphnidium but are different from reported fossil and extant species of Lindera. The cuticles of Lindera are fragile and delicate with only three Lindera fossils reported based on this tissue. In terms of paleobiogeography, the fossil record indicates that Lindera is distributed in high- to mid-latitude regions of the Late Cretaceous to Paleocene northern hemisphere. Coincidentally, the records of Lindera located on both sides of the Bering Land Bridge possibly support the hypothesis that ancient plants extended via transcontinental exchanges through the Bering Corridor. In the Eocene, ancient Lindera spread to Europe through the Northern Degeer Route and the Southern Thulian Route. At the same time, ancient Lindera spread into Central Asia. Climatic changes and tectonization since the Neogene prevented the propagation of Lindera throughout Asia, North America and Europe, and hence the distribution areas have just regressed to the low-latitude regions in Asia and North America. From the Paleogene to the Neogene, Lindera has changed its distribution by surviving extreme climate changes. Quaternary glaciations ultimately led to Lindera becoming extinct in Europe. The new record from Tengchong, Yunnan, with its lower latitude located in tropical and subtropical regions, indicates that Lindera has lived in those regions since the late Pliocene.
基金financially supported by the National Science Foundation of China (grant No. 41571177)
文摘Objective Large numbers of archeological relics from the Neolithic period are widely distributed in all tributaries of the Yellow River. The early humans tended to reside along the river valleys, and developed small but characteristically decentralized ancient valley culture. It is universally acknowledged that the agriculture exchange between China and western countries and the moderate
基金supported by NSFC(grant no.41173015)the China Scholarship Council(CSC)National Education Ministry Doctoral Foundation(grant no. 20100211110020).
文摘The central and northwestern Tibetan Plateau region,also called＂Qiangtang Plateau＂（30°27＇25＂-35°39＇13＂N,83o41＇14＂-95°10＇46＂E）,is the highest and largest arcticalpine area of the Earth covering approximately 600,000km^2 with altitude ranging from 4600 to 5100 m a.s.l.（Song et al.,2012,Fig.1）.
基金supported by the Second Tibetan Plateau Scientific Expedition(STEP)program(2019QZKK0704)the National Natural Science Foundation of China(grant number 42272029)the"Light of West China"Program of the Chinese Academy of Sciences(xbzglzb2022025).
文摘The Qaidam Basin,as the largest inland basin within the Tibetan Plateau,has accumulated more than 10,000 m of Cenozoic continental sediments.It serves as a crucial research area for documenting Cenozoic climate changes and plateau uplift processes in the Asian interior.Additionally,the basin holds vast reserves of oil and gas resources,making high-resolution drilling data invaluable for studying paleoclimate.In this study,the longsequence lacustrine deposits of JS1 drill core across the Shizigou Formation in the Yiliping Depression at the western center of the basin were studied,aiming to establish an astronomical timescale for the Shizigou Formation and investigate the characteristics of paleoclimatic changes during the late Miocene to the Pliocene for the Asian interior.The analysis was carried out using high-resolution natural gamma ray(GR)data sequences,employing techniques such as spectral analysis,filtering,and wavelet analysis in cyclostratigraphy.The results indicated the presence of a stable Milankovitch orbital signal was perfectly recorded in the Shizigou Formation,primarily influenced by eccentricity cycles,with weaker obliquity and precession cycles.Using the stable and continuous 405 ka eccentricity cycle in astronomical tuning,a"floating"astronomical timescale with a duration of 6.1 Ma for the Yiliping depression's Shizigou Formation has been established.With reference to previously established stratigraphic age anchor points,an absolute astronomical timescale(2.5–8.6 Ma)has been ultimately provided for the Shizigou Formation.Simultaneously,a clear 100 ka short eccentricity cycle record has been identified during the Pliocene(5.3–2.5 Ma),which corresponds in time with the aridification within the basin during this Pliocene period.In addition,a comparison of the Pliocene natural gamma ray curve of the Qaidam Basin with global ice volume variations indicated that the basin's aridification was influenced by global cooling,with eccentricity-modulated precession cycles controlling solar radiation and subsequently affecting the evolution of lakes in the arid region of Inner Asia.
基金financially supported by the Special Fund for the Land and Resources Scientific Research of Public Interest (201511020)
文摘The geodynamic processes for the Neoproterozoic mafic-ultramafic intrusions and dykes in the Kuluketage region,Tarim Craton has also been debated for some time.Some researchers suggested that the Neoproterozoic
基金financially supported by the National Science Foundation of China(grant No.41571177)
文摘Objective The lake levels in the eastern and southern Asia are regarded as low lake-level owing to precipitation decreasing based on the records of lake-level fluctuation in the continental interior lakes since the last glacial maximum（LGM）（14C 18±1 kaBP,since 20 kaBP）in the Central Asia.Higher lake-level appeared in the transition belt between western Kunlun Mountain and the central Tibetan Plateau.
