Chief Editor:HOU Zengqian
Governing Body:China Association for Science and Technology
Organizer:Geological Society of China
start publication :1922
ISSN:ISSN 1000-9515
CN:CN 11-2001/P
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2004, 78(1).
Abstract:The International Geological Congress held every four years is a grand event for displaying the latest achievements in geological science and technology and carrying out academic exchange.After the 31st IGC, the Chinese geologists, like their counterparts in the rest of the world, started to pay more attention to the issues facing the world today, including the shortage of energy and
GONG Enpu , HOU Lianhai , WANG Lixia Department of Geology , Northeastern University , Shenyang , Liaoning , Institute of Vertebrate Paleontology , Paleoanthropology , Chinese Academy of Sciences , Beijing Liaoning Department of Land , Resources , Shenyang , Liaoning
2004, 78(1).
Abstract:A Iarge number of enantiornithine birds are discovered from the Early Cretaceous Jiufutang Formation in western Liaoning, China. They are all small-sized birds with a few small teeth. The enantiornithine bird from the Jiufutang Formation in the Shangheshou area, Chaoyang, Liaoning Province reported in this paper is the largest individual known in all enantiornithine birds of the Early Cretaceous. However, its teeth possess a feature of pseudoheterodont. Some different development stages of the new teeth substitute the earlier stages and the stages of development are preserved in this specimen. This development pattern is similar to that of Archaeopteryx and alligator but not dinosaur. A well-developed postorbital was also preserved in the skull, which was a diapsidian skull like that of Confuciusornis. Additionally, the distinctive preservation of its prefrontal distinguishes it from other enantiornithine birds of the Early Cretaceous.
DENG Tao , WANG Xiaoming , NI Xijun , LIU LipingInstitute of Vertebrate Paleontology , Paleoanthropology , Chinese Academy of Sciences , Beijing , China , Natural History Museum of Los Angeles County , Los Angeles , CA , USA
2004, 78(1).
Abstract:In the Linxia Basin on the northeast margin of the Tibetan Plateau, the Cenozoic strata are very thick and well exposed. Abundant mammalian fossils are discovered in the deposits from the Late Oligocene to the Early Pleistocene. The Dzungariotherium fauna comes from the sandstones of the Jiaozigou Formation, including many representative Late Oligocene taxa. The Platybelodon fauna comes from the sandstones of the Dongxiang Formation and the conglomerates of the Laogou Formation, and its fossils are typical Middle Miocene forms, such as Hemicyon, Amphicyon, Platybelodon, Choerolophodon, Anchitherium, and Hispanotherium. The Hipparion fauna comes from the red clay of the Liushu and Hewangjia Formations, and its fossils can be distinctly divided into four levels, including three Late Miocene levels and one Early Pliocene level. In the Linxia Basin, the Hipparion fauna has the richest mammalian fossils. The Equus fauna comes from the Wucheng Loess, and it is slightly older than that of the classical Early Pleistocene Nihewan Fauna. The mammalian faunas from the Linxia Basin provide the reliable evidence to divide the Cenozoic strata of this basin and correlate them with European mammalian sequence.
YANG Xiangning , JIN Xiaochi , JI Zhansheng , WANG Yizhao , YAO Jianxin , and YANG Hailin Department of Earth Sciences , Nanjing University , Nanjing , Jiangsu , Institute of Geology , Chinese Academy of Geological Sciences , Baiwanzhuang Road , Beijing Geological Survey of Yunnan , Yujiang Road , Yuxi , Yunnan
2004, 78(1).
Abstract:Fossil materials of Shanita and Hemigordius from a section northeast of the Woniusi (the Woniu Temple) of Baoshan, western Yunnan are described and figured in this paper. Field investigation indicates that fossils of these two foraminifer genera are extremely abundant and form a typical Shanita-Hemigordius assemblage in the so-called "Cracked Limestone" in the Baoshan area. Preliminary study has revealed that the features of this assemblage, which includes Shanita amosi, S. chagouensis, Hemigordius renzi and H. biconcavus, are similar not only to the Shanita fauna previously reported from the Shazipo Formation in the Zhengkang area, west Yunnan, but also to those from the Permian of Burma, Thailand, Iran and Turkey.
XU Xing , WANG XiaolinInstitute of Vertebrate Paleontology , Paleoanthropology , Chinese Academy of Sciences , Beijing ,
2004, 78(1).
Abstract:A specimen collected from the Lower Cretaceous Yixian Formation of western Liaoning, China, represents a new genus and species of troodontid theropod. The new taxon is named and described on the basis of the holotype and the only known specimen, which comprises an articulated skeleton with the presacral vertebral, shoulder girdle and forelimbs missing as preserved. Diagnostic features of the new species include nasals that are sinusoid in lateral view, absence of a passage connecting the antorbital and maxillary fenestrae, relatively large teeth, plate-like chevrons forming a band along most of the length of the tail, and a long neck between the femoral head and shaft. The temporal constraints of the three paravian groups (Troodontidae, Dromaeosauridae and Aves) combined with the character distributions among the earliest known troodontids indicate a rapid evolution at the base of the Troodontidae.
XING Guangfu , YANG Zhuliang , CHEN Rong , SHEN Jialin , WEI Naiyi , ZHOU Yuzhang Nanjing Institute of Geology , Mineral Resources , Ministry of Land , Resources , Nanjing , Jiangsu ,
2004, 78(1).
Abstract:There are large-scale Mesozoic bimodal igneous rock associations on the continental margin of southeastern China. They aroused extensive attention in the 1980s because of their specific tectonic implications, and have been found frequently during recent geological surveys. This paper reviews the studies of regional Mesozoic bimodal rocks, and concludes that they can be subdivided into three stages, i.e., the Early Jurassic (209-170 Ma, the first (Ⅰ) stage), the Late Jurassic-early Early Cretaceous (154-121 Ma, the second (Ⅱ) stage), and the late Early Cretaceous-Late Cretaceous (115-85 Ma, the third (Ⅲ) stage). These three stages of bimodal rocks were formed in different tectonic settings, and are important indicators for regional Mesozoic tectonic evolution.
ZHANG Zhaochong , HAO Yanli , WANG Fusheng , John J. MAHONEYInstitute of Geology , Chinese Academy of Geological Sciences , Beijing , ChinaSchool of Ocean , Earth Science , Technology , University of Hawaii , Honolulu , HI , USA
2004, 78(1).
Abstract:Electronic microprobe analyses for olivine, clinopyroxene and Cr-spinel in picrites, which we have discovered recently in the Emeishan continental flood basalt province (ECFBP), show that the olivine is rich in Mg, and that Cr-spinel is rich in Cr. Based on the olivine-melt equilibrium, the primary parental melt compositions are calculated. The high-Mg olivine-hosted picrite can be regarded as parental melt. Thus, the melting temperature and pressure are estimated: T=1600℃ and P=4.5 GPa. It suggests that the picrites are connected with the activity of mantle plumes. Their major element composition is comparable to many other CFBs by their high Fe8, (CaO/Al2O3)8 and low Na8, indicating a high pressure. All rocks display a similar chondrite-normalized REE patterns, i.e., enrichment of LREE, relative depletion of HFSE and absence of negative Nb and Ta but depletion in P and K. Some incompatible element ratios, such as La/Ta, La/ Sm, (La/Nb)PM, (Th/Ta)PM, are in a limited range, show that they were derived
LIU Jianmin , DONG Shuwen , ZHANG Jiasheng , LIU Xiaochun , CHEN Bailin Institute of Geomechanics , CAGS , Beijing , Institute of Geology , Chinese Seismological Bureau , Beijing
2004, 78(1).
Abstract:Recent field survey in the eastern Dabieshan Mountains has revealed extensive occurrences of pseudotachylite. The pseudotachylite tends to occur as simple veins and injected networks along the NE-SW-trending fracture zones or shear zones, which are parallel to the Tanlu fault zone and cut all the pre-Cretaceous geological bodies. The characteristics of both the microstructures gained by the optical microscope and SEM imaging and the geochemistry between the pseudotachylites and their host rocks show that the pseudotachylites were formed mainly by ultracataclasis of their wall rocks in which they occur. The bulk K-Ar ages of the pseudotachylites yielded a narrow range of 81 -93 Ma, and moreover the laser-probe 40Ar/39Ar dating of phengite overprinting on the pseudotachylite gave a weighted mean age of 78.9 Ma. These results show that the pseudotachylites from the eastern Dabieshan Mountains formed along the NE-SW-trending fault zone during the uplifting of the orogenic belt at 80-90 Ma, which places important constrains on the cooling and exhumation history of the Dabieshan Mountains during and after the late Cretaceous.
XIAO Long , XU Yigang , XU Jifeng , HE Bin , Pirajno FRANCOFaculty of Earth Sciences , China University of Geosciences , Wuhan , Hubei , Guangzhou Institute of Geochemistry , Chinese Academy of Sciences , Guangzhou , Guangdong Geological Survey of Western Australia , Plain Street , East Perth WA , Australia
2004, 78(1).
Abstract:The Late Permian Emeishan Large Igneous Province (ELIP) is commonly regarded as being located in the western part of the Yangtze craton, SW China, with an asymmetrical shape and a small area. This area, however, is just a maximum estimation because some parts of the ELIP were not recognized or dismembered and destroyed during the Triassic to Cenozoic tectonism. In this paper, the chemostratigraphical data of the Zongza block, the Garze-Litang belt and the Songpan-Garze block suggest that the Late Permian basalts in these areas have remarkable similarities to the ELIP basalts in petrography and geochemistry. Flood basalts in the Sanjiangkou area are composed of the lower part of the low-Ti (LT) tholeiite and the upper part of the high-Ti (HT) tholeiite, which is the same as the flood basalts on the western margin of the Yangtze craton. Flood basalts in the Zongza and Songpan-Garze areas, which are far from the Yangtze craton, consist of HT tholeiite only. This is the same as the flood basalts within the Yangtze craton. Therefore we argue that these contemporary basalts all originated from the Emeishan mantle plume, and the ELIP could have a significant westward extension with an outcropped area of over 500,000 km2. This new scenario shows that the LT tholeiite occurs on the western margin of the Yangtze craton, while the HT tholeiite overlying the LT basalts occupies the whole area of the ELIP.
ZHAO Zhenhua , XIONG Xiaolin , WANG Qiang , BAI Zhenghua , XU Jifeng , QIAO Yulou Guangzhou Institute of Geochemistry , Chinese Academy of Sciences , Guangzhou , Guangdong ,
2004, 78(1).
Abstract:The late Paleozoic adakitic rocks are closely associated with the shoshonitic volcanic rocks in the western Tianshan Mountains, China, both spatially and temporally. The magmatic rocks were formed during the period from the middle to the late Permian with isotopic ages of 248-268 Ma. The 87Sr/86Sr initial ratios of the rocks are low in a narrow variation range (-0.7050). The 143Nd/144Nd initial ratios are high (-0.51240) with positive εND(t) values (+1.28-+4.92). In the εNd(t)-(87Sr/86Sr)i diagram they fall in the first quadrant. The association of the shoshonitic and adakitic rocks can be interpreted by a two-stage model: the shoshonitic volcanic rocks were formed through long-term fractional crystallization of underplated basaltic magma, while the following partial melting of the residual phases formed the adakitic rocks.
ZHANG Chengli , LI Miao , WANG Tao , YUAN Honglin , YAN Yunxiang , LIU Xiaoming , WANG Jianqi , LIU YeThe Key Laboratory of Continental Dynamics , Ministry of Education , Department of Geology , Northwest University , Xi''''an , Shaanxi , State Key Laboratory for Mineral Deposits Research , Nanjing University , Nanjing , Jiangsu Institute of Geology , Chinese Academy of Geological Sciences , Beijing
2004, 78(1).
Abstract:LA-ICPMS U-Pb zircon dating of the Sanpinggou, Gangou and Fengzishan granitoids in the Douling Group of the Eastern Qinling yields ages of 760-685 Ma, which represents a strong tectono-magmatic event in the southern Qinling during the late Neoproterozoic. Geochemical data show that these intrusions have wide compositions ranging from minor gabbros through diorites to granodiorites. They are relatively enriched in LILE, poor in HFSE and strongly depleted in Nb and Ta, displaying affinities of Ⅰ-type granites formed in an active continental margin with oceanic subduction. In contrast to granitoids, gabbros and enclaves in the granitoids have higher REE abundances, relatively flat REE patterns, lower LILE, slightly higher HFSE and more depletion in Nb and Ta. All these suggest that the gabbros were formed by partial melting of the upper mantle above the subduction zone and the granitoids by the partial melting of the lower crust. Combined with regional geological data, the subduction-related granitoids in
XU Wenliang , WANG Qinghai , LIU Xiaochun , WANG Dongyan , GUO Jinghui College of Earth Sciences , Jilin University , Changchun , Jilin , Institute of Geomechanics , Chinese Academy of Geological Sciences , Beijing Institute of Geology , Geophysics , Chinese Academy of Sciences , Beijing
2004, 78(1).
Abstract:SHRIMP zircon U-Pb dating in the Liguo and Jiagou intrusives indicates that they were formed at -130 Ma in the Early Cretaceous. Most inherited zircons in the Liguo intrusive were formed at 2509±43 Ma. Most inherited and detrital zircons in the Jiagou intrusive were formed at -2500 Ma, -2000 Ma and -1800 Ma. The SHRIMP zircon U-Pb dating in two gneiss xenoliths from the Jiagou intrusive yields the ages of 2461±22 Ma and 2508±15 Ma, respectively. The dating results from inherited and detrital zircons in the intrusives and the gneiss xenoliths imply that the magmas could be derived from the partial melting of the basement of the North China Block (NCB). The magmatism is strong and extensive in the periods from 115 to 132 Ma, which is of typical bimodal characteristics. It is suggested that the lithospheric thinning in the eastern North China Block reached its peak in 115-132 Ma.
LAI Shaocong , ZHANG Guowei , LI SanzhongKey Laboratory of Continental Dynamics , Ministry of Education , Department of Geology , Northwest University , Xi''''an , Shaanxi , College of Earth Science , Ocean University of Qingdao , Qingdao , Shandong
2004, 78(1).
Abstract:The Mianlue suture extends from Derni-Nanping-Pipasi-Kangxian to the Lueyang-Mianxian area, then traverses the Bashan arcuate structure eastward to the Huashan region, and finally to the Qingshuihe area of the southern Dabie Mountains. From east to west, with a length of over 1500 km, the ophiolitic melange associations are distributed discontinuously along the suture. The rock assemblages include ophiolite, island-arc and oceanic island rock series, indicating that there existed a suture zone and a vanished paleo-ocean basin. The Mianliie paleo-ocean basin experienced its main expansion and formation process during the Carboniferous-Permian and closed totally in the Triassic. It belongs to the northern branch of the eastern paleotethys, separated from the northern margin of the Yangtze block under the paleotethys mantle dynamic system.
WU Xiuling , MENG Dawei , HAN Yujing Testing Centre , China University of Geosciences , Wuhan , Hubei ,
2004, 78(1).
Abstract:Fluid inclusions at a nano to sub-micron scale in quartz from jadeite quartzite at Shuanghe, Dabie Mountains, have been investigated by using the transmission electron microscopy (TEM). Most fluid inclusions are spherical or negative crystal shaped, forming wide swarm-like trails. The TEM reveals that the relationship between coesite and the host quartz is syntaxic and provides strong evidence of the occurrence of high-salty fluids at peak metamorphic conditions. The fluid inclusions are often connected to dislocations, which are undetected at the scale of optical microscopy. Non-decrepitation leakage of fluid inclusions may occur by pipe diffusion of molecule H2O or CO2 along dislocations from the inclusions into the host quartz, thus leading to original inclusion density and composition changes. It should be taken into full account for the correct petrological interpretation of micro-thermometric results.
ZHANG Mingjie , WANG Xianbin , LIU Gang , ZHANG Tongwei , BO WenruiInstitute of Geological Science , Lanzhou University , Lanzhou , Gansu , Key Lab of Gas-Geochemistry , Lanzhou Institute of Geology , CAS , Lanzhou , Gansu First Institute of Oceanography , State Oceanic Administration , Qingdao , Shandong
2004, 78(1).
Abstract:The composition of gases trapped in olivine, orthopyroxene and clinopyroxene in Iherzolite xenoliths collected from different locations in eastern China has been measured by the vacuum stepped-heating mass spectrometry. These xenoliths are hosted in alkali basalts and considered as residues of partial melting of the upper mantle, and may contain evidence of mantle evolution. The results show that various kinds of fluid inclusions in Iherzolite xenoliths have been released at distinct times, which could be related to different stages of mantle evolution. In general, primitive fluids of the upper mantle (PFUM) beneath eastern China are dominated by H2, CO2 and CO, and are characterized by high contents of H2 and reduced gases. The compositions of PFUM are highly variable and related to tectonic settings. CO, CO2 and H2 are the main components of the PFUM beneath cratons; the PFUM in the mantle enriched in potassic metasomatism in the northern part of northeastern China has a high content of H2, while CO2 and SO2 are the dominant components of the PFUM in the Su-Lu-Wan (Jiangsu-Shandong-Anhui) region, where recycled crustal fluids were mixed with deeper mantle components. There are several fluids with distinct compositions beneath eastern China, such as primitive fluids of upper mantle (CO, CO2 and H2), partial melting fluids (CO2 and CO) and metasomatic fluids mixed with recycled crustal fluids (CO2, N2, SO2 and CH4) etc. Fluids of the upper mantle beneath the North China craton are different from that of the South China craton in total gases and chemical compositions: the contents of the reduced gases of the PFUM in the NCC are higher than those in the SCC.
DU Yangsong , LEE Hyunkoo , QIN Xinlong Key Laboratory of Lithosphere Tectonics , Exploration , Ministry of Education , Xueyuan Road , Beijing , Faculty of Earth Sciences , Mineral Resources , China Universityof Geosciences , Xueyuan Road , Beijing Department of Geology , Chungnan National University , Kungdong , Yuseong Ku , Taejon - , Republic of Korea
2004, 78(1).
Abstract:Lithological observations and mineralogical analyses on pyroxene and hornblende megacrysts and pyroxene and hornblende cumulates in xenoliths in the Mesozoic plutons of the Tongling region, Anhui Province, provide evidence for the magmatic underplating of mantle-derived alkali-olivine basalt at circa 140 Ma. The pyroxene and hornblende megacrysts and cumulates were formed through the AFC process at depths ranging from 27 to 35 km.
LIU Liang , CHEN Danling , ZHANG Anda , ZHANG Chengli , YUAN Honglin , LUO Jinhai The Key Laboratory of Continental Dynamics , Department of Geology , Northwest University , Xi''''an , Shaanxi
2004, 78(1).
Abstract:Geochemical studies on the arnphibolites in the Songshugou ophiolite from Shangnan County, Shaanxi Province demonstrate that the protolith of the amphibolites is tholeiitic. The arnphibolites can be classified into two groups according to their REE patterns and trace element features. Rocks of the first group are depleted in LREE while rocks of the second group are slightly depleted in LREE or flat from LREE to HREE without significant Eu anomaly. The first group of rocks have (La/Yb)N=0.33-0.55, (La/Sm)N= 0.45-0.65, and their La/Nb, Ce/Zr, Zr/Nb, Zr/Y and Ti/Y ratios are averaged at 1.20, 0.12, 31.02, 2.92 and 198, respectively, close to those of typical N-MORB. The second group of rocks have (La/Yb)N=0.63-0.95, (La/ Sm)N = 0.69--0.90, and their average La/Nb, Ce/Zr, Zr/Nb, Zr/Y and Ti/Y ratios are 0.82, 0.83, 1.15, 0.16, 19.00, 2.58 and 225, respectively, which lie between those of typical N-MORB and E-MORB but closer to the former. The two groups of rocks both exhibit flat patterns from Th to Yb in th
LI HongyanInstitute of Mineral Resources , Chinese Academy of Geological Sciences , Beijing , Geosciences Rennes , Universite de Rennes , Rennes Cedex , France
2004, 78(1).
Abstract:An unusual zircon SHRIMP dating result of a granitic gneiss from the Qinglongshan eclogite-gneiss roadcut section is presented in this paper. The very peculiar and complicated internal structures, as well as the very low Th/U ratios (0.01-0.08) of the zircons indicate that they were formed by metamorphic recrystallization. Strongly in contrast with previously published zircon U-Pb ages of the Dabie-Sulu UHP metamorphic rocks where protolith ages of 600-800 Ma are commonly recorded, only metamorphic age of 218±5 Ma, defined by 18 analytical spots either in rim or in core of zircons, are recorded in this granitic gneiss. This age represents the time of the complete metamorphic recrystallization overprint on primary magmatic zircons. The recrystallization was derived by the UHP metamorphism, and was strengthened by the early stage of retrograde metamorphic fluid activity.
HU Daogong , WU Zhenhan , JIANG Wan , YE Peisheng Institute of Geomechanics , Chinese Academy of Geological Sciences , Beijing ,
2004, 78(1).
Abstract:Mafic granulites have been found as structural lenses within the huge thrust system outcropping about 10 km west of Nam Co of the northern Lhasa Terrane, Tibetan Plateau. Petrological evidence from these rocks indicates four distinct metamorphic assemblages. The early metamorphic assemblage (M1) is preserved only in the granulites and represented by plagioclase+hornblende inclusions within the cores of garnet porphyroblasts. The peak assemblage (M2) consists of garnet+clinopyroxene+hornblende+plagioclase in the mafic granulites. The peak metamorphism was followed by near-isothermal decompression (M3), which resulted in the development of hornblende+plagioclase symplectites surrounding embayed garnet porphyroblasts, and decompression-cooling (M4) is represented by minerals of hornblende+plagioclase recrystallized during mylonization. The peak (M2) P-T conditions of garnet+ clinopyroxene+plagioclase+hornblende were estimated at 769-905℃ and 0.86-1.02 GPa based on the geothermometers and geobarometers. The
MENG Dawei , DING Xiaokun , WU XiulingFaculty of Materials Science , Chemical Engineering , China University ofGeosciences , Wuhan , Hubei Testing Centre , China University of Geosciences , Wuhan , Hubei
2004, 78(1).
Abstract:The process and path of retrometamorphism of coesite have great significance to our understanding of the P-T tracks of the exhumation of ultrahigh-pressure metamorphic rocks. Most of the coesites in the eclogite from Shima, Anhui Province, the Dabie Mountains, China, are found degraded to quartz partly or wholly, with ruptures occurring in the shells, outside which include the coesite and quartz. According to the microscopic observation, the sample of coesite inclusion is composed of garnet, quartz and coesite, based on which we have built a three-shelled composite sphere model to compute the transition of coesite. Based on the crystal growth formulas and pressure conditions of the ruptures in the garnet, we have calculated the radius of the quartz sphere, which depends on temperature, and eventually drawn the different retrometamorphic paths for different retrometamorphism rates.
WANG Hejing , CHEN Tao , WANG Huan , ZHANG Zuqing"Orogene , Crust Evolution " Key Laboratory of the Ministry of Education of China , School of Earth , Space Sciences , Peking University , Beijing ,
2004, 78(1).
Abstract:The Neoproterozoic and Lower Paleozoic along the profile of Yuanguping in western Hunan Province, China underwent anchimetamorphism. The illite crystallinity (IC) of the <2 μm fractions ranges from 0.23-0.34°△2θfor the Neoproterozoic to 0.23-0.35°△A2θ for the Lower Paleozoic (calibrated with the Kisch IC set, Kisch, 1991). This indicates that the metamorphic grade of the Neoproterozoic and Lower Paleozoic is the anchizone. The peak metamorphic temperature is estimated to be 290-210℃. This result does not agree with the greenschist or subgreenschist facies of the Banxi Group, nor with the lower-greenschist facies or sedimentary cover of the Sinian to Lower Paleozoic, as most previous researchers thought. The illite (K-mica) b0 values range from 0.9074 to 0.8963 (nm) for the Neoproterozoic and the Lower Paleozoic. Based on cumulative frequency curves of the illite (K-mica) b0, the peak metamorphic pressure of the Banxi Group was derived to be of a type that is slightly higher than that of the N. Ne
ZHAO Guiping , LIU Shuwen , LIU Xiaohan Computational Geodynamics Laboratory , Graduate School of Chinese Academyof Sciences , Beijing , School of Earth , Space Sciences , Peking University , Beijing Institute of Geology , Geophysics , Chinese Academy of Sciences , Beijing
2004, 78(1).
Abstract:Although porphyroblast microstructures play an important role in structural and metamorphic studies, there are still controversies in the interpretation. The focus is how porphyroblasts grow during deformation and metamorphism. In this paper, we introduce a new approach, the Synchrotron Radiation X-Ray Fluorescence, to a hemi-quantitative interpretation of the growth mode of porphyroblasts. The analysis was done at the Beijing Synchrotron Radiation Facility. The specimens were sampled from metapelite of the Baoyintu Group, northern Urad Middle Banner, Inner Mongolia. The new method is successful for determining the microscopic distribution of trace elements in porphybroblasts. The results support the theory of deformation partition, which has been brought forth by Bell and his colleagues, and demonstrate the existence of porphyroblast growth phases and the growth mode of porphyroblasts by hemi-quantitative mineral chemical analysis. The porphyroblast grows stage by stage in the manner of the distribution of a roseleaf and is controlled by deformation. We call the growth stage of porphyroblast a growth phase.
LU Anhuai School of Earth , Space Sciences , Peking University , Beijing ,
2004, 78(1).
Abstract:The investigation of the environmental properties of minerals, i.e., environmental mineralogy, is a branch of science dealing with interactions between natural minerals and spheres of the Earth surface as well as a reflection of global change, prevention of ecological destruction, participation in biomineralogy, and remediation of environmental pollution. Pollutant treatment by natural minerals is based on the natural law and reflects natural self-purification functions in the inorganic world, similar to that of the organic world - a biological treatment. A series of case studies related to natural self-purification, which were mostly completed by our group, are discussed in this paper. In natural cryptomelane there is a larger pseudotetragonal tunnel than that formed by [MnO6] octahedral double chains, with an aperture of 0.462-0.466 nm2, filled with K cations. Cryptomelane might be a real naturally-occurring mineral of the active octahedral molecular sieve (OMS-2). CrⅥ-bearing wastewater can be treate
HOU Zengqian , YANG Zhusen , LI Yinqing , ZENG Pusheng , MENG Yifeng Institute of Mineral Resources , Chinese Academy of Geological Sciences , Beijing ,
2004, 78(1).
Abstract:The middle-lower Yangtze area underwent a series of complex tectonic evolution, such as Hercynian extensional rifting, Indosinian foreland basining, and Yanshanian transpression-transtension, resulting in a large distinctive Cu-Fe-Au metallogenic belt. In the tectonic evolution, large-scale migration and convergence of fluids toward foreland basins induced during the collisional orogeny of the Yangtze and North China continental blocks were of vital importance for the formation of the metallogenic belt. Through geological surveys of the middle-lower Yangtze area, three lines of evidence of large-scale fluid migration are proposed: (1) The extensive dolomitic and silicic alteration penetrating Cambrian-Triassic strata generally occurs in a region sandwiched between the metallogenic belt along the Yangtze River and the Dabie orogenic belt, and in the alteration domain alternately strong and weak alteration zones extend in a NW direction and are controlled by the fault system of the Dabie orogenic belt; it might record the locus of the activities of long-distance migrating fluids. (2) The textures and structures of very thick Middle-Lower Triassic anhydrock sequences in restricted basins along the river reveal the important contribution of the convergence of regional hot brine in restricted basins and the chemical deposition or their formation. (3) Early-Middle Triassic syndepositional iron carbonate sequences and Fe-Cu-Pb-Zn massive sulfide deposits alternate with anhydrock sequences or are separated from the latter, but all of them occur in the same stratigraphic horizon and are intimately associated with each other, being the product of syndeposition of high-salinity hot brine. According to the geological surveys, combined with previous data, the authors propose a conceptual model of fluid migration-convergence and mineralization during the Dabie collisional orogeny.
HU Wenxuan , JIN Zhijun , SONG Yucai , SUN Rui , DUAN Zhenhao State Key Laboratory of Mineral Deposits Research , Department of Earth Sciences , Nanjing University , Nanjing , Jiangsu , Basin , Reservoir Research Center , Petroleum University , Changping , Beijing Institute of Geology , Geophysics , Chinese Academy of Sciences , Beijing
2004, 78(1).
Abstract:Based on a set of equations established by Duan et al. (1992, 1996) for a geofluid system H2O-CO2-CH4(-N2), a formula is obtained to calculate the heat changes. Combining the geological T-P conditions (geothermal gradients and lithostatic and hydrostatic pressures), the enthalpy of some typical geofluids is figured out. Then the principles of heat transfer of deep-derived supercritical fluids are discussed. The result shows that deep-derived geofluids can bring a large amount of thermal heat and release most heat to the shallow surroundings as they move up, because the molar enthalpies vary very greatly from the deep to shallow, increasing with the increases of T and P. Generally, more than tens of kilojoules heat per molar can be released. Furthermore, the molar enthalpy is affected by the compositions of the geofluids, and the molar enthalpy of CO2, CH4, or N2 is greater than that of H2O, being twice, more than twice, and about 140% of H2O, respectively. Finally, a case study is conducted by investigat
YIN Hongfu , ZHANG Kexin , FENG Qinglai China University of Geosciences , Wuhan , Hubei
2004, 78(1).
Abstract:Unlike typical oceans such as the wide and "clean" Atlantic, the Tethys has been showing an archipelagic pattern during all its evolutionary stages. Compared with the traditional, wedge-shaped and relatively "clean" ocean model, the archipelagic model is more suitable for the Tethys, especially the eastern Tethys. This paper demonstrates the eastern Tethys archipelagic system in terms of the subdivision, characteristics and evolutionary history of the Qinling-Qilian-Kunlun, South China and Xizang (Tibet)-Yunnan Regions of the eastern Eurasian Tethys.
WANG Xinshe , ZHENG Yadong , JIA Wen Department of Earth , Space Science , Peking University , Beijing , Institute of Geology , Chinese Academy of Geological Science , Beijing No. Institute of Geological , Resource Exploration of Inner Mongolia , Chifeng
2004, 78(1).
Abstract:The Louzidian metamorphic core complex (LMCC) in southern Chifeng is located on the northern margin of the North China craton. Structural analyses of the LMCC and its extensional detachment system indicate that the LMCC experienced two-stage extension. The ductile regime experienced top-to-northeast shearing extension and the brittle detachment fault underwent top-down-outwards slipping. Between these two stages, a semi-ductile regime recorded the transition from ductile to brittle. The hanging wall of the detachment fault is similar to those classic supradetachment basins in western North America. Analyses of provenance and paleocurrent directions in the basins show that there were two filling stages. In the early stage, materials came from the southwest margin of the basin and the hanging wall of the detachment system and were transported from southwest to northeast; while in the late stage, deposits were derived from the footwall of the detachment fault and transported outwards to the two sides of the
Wu Zhenhan , Hu Daogong , Ye Peisheng , Zhao Xun , Liu Qisheng Institute of Geomechanics , Chinese Academy of Geological Sciences , Beijing , Chinese Academy of Geological Sciences , Beijing
2004, 78(1).
Abstract:A huge thrust system, the North Lhasa Thrust (NLT), was discovered in the northern Lhasa block of the Tibetan Plateau based on geological mapping of the Damxung region and its vicinity, the Deqen-Lunpola traverse and the Amdo-Bam Co profile. The NLT consists of the Dongqiao-Lunpola thrust (DLT), the west Namco thrust (WNT) and the south Damxung thrust (SDT) and ductile shear zones, ophiolite slices and folds extending in a WNW direction. Major thrust faults of the NLT seem to merge into a single deep-seated detachment of the upper-crust and totally displaced southward as far as 100-120 km. Chronological analyses with 39Ar-40Ar of plagioclase and hornblende, Rb-Sr isochron of minerals and fission-tracks of apatite from mylonite within the WNT yield ages of 174-173 Ma, 109 Ma and 44 Ma, showing 3 periods of thrusting in the north Lhasa block caused by subduction of the Tethys oceanic plate and the India-Eurasia continental collision respectively.
DENG Jinfu , SU Shangguo , MO Xuanxue , ZHAO Guochun , XIAO Qinghiu , JI Guangyi , QIU Ruizhao , ZHAO Hailing , LUO Zhaohua , WANG Yang , LIU Cui China University of Geosciences , Beijing , Key Laboratory of Lithospheric Tectonics , Lithoprobe Techniques , Ministry of Education of China
2004, 78(1).
Abstract:This paper emphasizes that the interactive constraints of geology and isotopic dating is the best approach to construct the geological event sequence, and has compiled 106 data of reasonable isotopic ages for the igneous rocks of the Yanshan belt. We propose a sequence of mgmatic-tectonic events in the Jurassic-Cretaceous Yanshan orogen of North China. Five orogenic episodes are divided, (1) pre-and initial orogenic episode (Early Jurassic); (2) early orogenic episode (Middle Jurassic); (3) peak orogenic episode (Late Jurassic); (4) late orogenic episode (early Early Cretaceous), and (5) post-orogenic episode. Each episode is a short cycle, all of the orogenic processes construct a longer cycle, and they, in general, followed a counter-clockwise (ccw) PTt path. Finally, it is suggested that the Yanshanian movement was so intensive that the magmatism and tectonic deformation had involved all the lithosphere thickness and the late-Achaean-formed cratonic lithosphere had been significantly reworked.
DENG Jun , HUANG Dinghua , WANG Qingfei , HOU Zengqian , LU Qingtian , YAOLingqing , XIN Hongbo , ZHANG Qiang , WEI YanguangKey Laboratory of Lithospheric Tectonics , Exploration , China University of Geosciences , Beijing , Ministry of Education , Beijing , China University of Geosciences , Wuhan , Hubei Institute of Mineral Resources , Chinese Academy of Geological Sciences , Beijing
2004, 78(1).
Abstract:Almost all intraplate caprocks experienced strong deformation during the convergence of microplates, and then disintegrated into many secondary geologic units with the special characters, such as irregular boundaries and particular structural assemblages. In order to understand the formation mechanism of these special phenomena, a rheological experiment on the structural scenery of the Tongling area is carried out. The result shows that the primary regular and uniform boundaries of the Tongling area becomes irregular because of the enclosing and confinement of surrounding geological units in the process of "compression-shearing-rotation-drag"; simultaneously, two specific "drag depressions" developed at two opposite corners of the block. The former and the later phenomena can be regarded as a typical regional-scale rheological effect and necessary outcome of intraplate deformation respectively.
WU Zhonghai , ZHAO Xitao , WU Zhenhan , JIANG Wan , HU Daogong , ZHOU Chunjing Institute of Geomechanics , Chinese Academy of Geological Sciences , Beijing , Institute of Geology , Geophysics , Chinese Academy of Sciences , Beijing
2004, 78(1).
Abstract:The detailed geological mapping, conducted in the Damxung-Yangbajain basin, shows that there are many types of deposits formed since the Pliocene. The oldest sediments are formed during the Pliocene. The most prominent sediments are three sets of moraines and fluvioglacial deposits. The ESR, U-series and OSL dates indicate they are formed about 700-500 ka B.P., 250-125 ka B.P. and 75-12 ka B.P. respectively and indicate that there are three glacial periods since the mid-Pleistocene in the Nyainqentanglha Range. Along the southeast side of the Nyainqentanglha Range, the main southeast dipping fault zone which bounds the Damxung-Yangbajain Graben on its western edge was mapped. The fault zone consists of three secondary fault zones and their initiation ages that the fault zones became active gradually decrease southeastward. Prominent faulting occurred in about 700-500 ka B.P., 350-220 ka B.P., -140 ka B.P. and 70-50 ka B.P. since the mid-Pleistocene. The height of fault scarps which offset the sediments f
SUN Aiqun , NIU Shuyin , SHAO Ji''''an , HOU Quanlin , ZHANG Jianzhen Shijiazhuang College of Economics , Shijiazhuang , Hebei , School of Earth , Space Sciences , Peking University , Beijing Institute of Geology , Geophysics , Chinese Academy of Sciences , Beijing
2004, 78(1).
Abstract:The basin-and-range area in eastern North China is known for frequent occurrence of earthquakes, their great magnitudes and heavy losses thereby incurred. Seismic studies in the past usually emphasized the intersections, inflexions and branches of the faults. However, the intensities of many great earthquakes in this area do not show linear distribution, and the epicenters are horizontally dispersed at certain depths instead of along the strike of faults. Based on the sub-mantle plume studies made by authors in the past decade, it is thought that there exists an uplifted sub-mantle plume under the fault depression area in North China. The uplifting and intrusion of mantle materials caused the upper crust to be faulted, while low-velocity and high-velocity layers are alternatively distributed in the middle crust under the influence of the mantle and the lower crust. The middle and lower crust materials were detached from the top of the sub-mantle plume to the surroundings while the sub-mantle plume materials were detached outward. When the detached middle and lower crust come to the boundary of fault basins in the upper crust, they will be obstructed by the orogenic zone and the detachment will go slower. The shearing between them will cause the stress to accumulate and release alternatively, so that earthquakes occurred frequently in the areas of sub-mantle plume and its surroundings.
WANG Yang , CAO Jiamin , ZHU Jieshou Guangzhou Institute of Geochemistry , Chinese Academy of Sciences , Guangzhou , Guangdong , School of Earth Sciences , Resources , China University of Geosciences , Beijing Department of Geophysics , Chengdu University of Technology , Chengdu , Sichuan
2004, 78(1).
Abstract:On the basis of a one-by-one latitude-longitude grid three-dimensional seismic velocity model, the crustal P-wave velocity structure in eastern China (105-125°E and 18-41°N) is obtained, and a set of geotherms for each grid is established for P-T correction on P-wave velocities. The average depths of sub-crustal layers and their average P-wave velocities of 18 tectonic units in eastern China are exhibited. Our result presents a 32-34 km thick crust beneath eastern China, which is thinner than previous studies, with an average velocity of 6.54 km/s, corresponding to a 5 kg/m3 variation in crustal mean density. The thicker upper but thinner middle and lower crust results in a lower average seismic velocity of eastern China. An intermediate crustal composition with a SiO2 content of 59.7 wt% has been estimated. However, there exists a significant lateral variation in the crustal structures among the tectonic units of eastern China. The structure and composition features of some regions in eastern China in
LI Zhongquan , XU Shihai , YING Danlin , Han Jianhui State Key Loboratory of Oil , Gas Reservoir Geology , Exploration , Chengdu University ofTechnology , Chengdu , Sichuan , PetroChina Company Limited Southwest Oil , Gas Field Company Exploration , Development Research Institute , Chengdu , Sichuan
2004, 78(1).
Abstract:Angular unconformity is one of the most direct and strongest evidences for approving the tectonic movements of the earth's crust. Its dynamic genesis process has been understood to be mainly related to the compressional setting for a long time. Especially, in a detailed structural analysis for a specific region, when an angular unconformity is discovered people would regard it as the result of orogenic movements of a certain period or a certain episode and neglect the extensional facts. Based on a dialectical point of view of extension-compression, this paper has proved that angular unconformities can be formed not only in compressional settings, but also in extensional ones. Further more, their geological features are compared and he possible genetic mechanisms for angular unconformity under different dynamic settings are studied.
NIU Shuyin , SHAO Ji''''an , HOU Quanlin , WANG Baode , XU Chuanshi Shijiazhuang University of Economics , Shijiazhuang , Hebei , School of Earth , Space Science , Peking University , Beijing Institute of Geology , Geophysics , Chinese Academy of Science , Beijing
2004, 78(1).
Abstract:The basin-range coupling relation is a leading subject of the modern geology. In geometry, relations of this type include couplings between stretched orogenic belt and down-faulted basin, compressional orogenic belt and foreland basin, strike-slip orogenic belt and strike-slip basin and so on. Fault chains are the key for these couplings and there are typical examples for all these cases. The North China down-faulted basin is coupled west with the Taihang uplift, east with the Jiao-Liao Mountains, north with the Yanshan orogenic belt and south with the Dabie orogenic belt, that is to say, the central down-faulted basin and the surrounding orogenic belts bear a coupling relation within a uniform dynamistic system. Study shows that the central down-faulted basin and the North China mantle sub-plume structure have a close relation during their formation. Owing to intensive mantle sub-plume uplifting, the bottom of the lithosphere suffered from resistance, which caused the lithosphere of the eastern North China to be heated, thinned and fault-depressed. Meanwhile, mantle rocks that were detached outwards in the shape of mushroom was dissected by surrounding ductile shearing zones, which lead to decompression and unloading to generate hypomagmas, and a series of mantle-branch structures were formed around the down-faulted basin. There is an obvious comparability among these mantle branch structures (orogenic belts), and they have basin-range coupling relations with the central down-faulted basins.
SHAO Ji''''an , ZHAI Mingguo , ZHANG Luqiao , LI Daming Faculty of Earth , Space Sciences , Peking University , Beijing , Institute of Geology , Geophysics , Chinese Academy of Sciences , Beijing Institute of Mineral Deposit , Experiment , Inner Mongolia , Hohhot , Inner Mongolia Institute of Geology , China Seismological Bureau , Beijing
2004, 78(1).
Abstract:Dike swarms are generally ascribed to intrusion of mantle-source magma result from extension. Basic dike swarms around the Shanxi-Hebei-Inner Mogolia borders in the northern peripheral area of the North China Craton can be divided into five age groups according to isotopic dating: 1800-1700 Ma, 800-700 Ma, 230 Ma, 140-120 Ma, and 50-40 Ma. Geological, petrological and isotope geochemical features of the five groups is investigated in order to explore the variation of the mantle material composition in the concerned area with time. And the various extensional activities reflected by the five groups of dike swarms are compared with some important tectonic events within the North China Craton as well as around the world during the same period.
2004, 78(1).
Abstract:The Discovery of Balmeisporites from the Taipinglinchang Formation in the Jiayin Basin, Heilongjiang and Its SignificanceWAN Chuanbiao, LIU Benpei, QIAO Xiuyun, YANG Jianguo, SHAN Xuanlong and REN Yanguang (1.College of Earth Science of Jilin University, Changchun 130026; 2. College of Earth Science of China University of Geosciences, Beijing 100083; 3. Exploration and Development Research Institute of Daqing Oil Field Company Ltd., Daqing, Helongjiang 163712; 4 College of Earth and Space of Peking University, Beijing 100871)
2004, 78(1).
Abstract:Papers should be devoted mainly to various aspects of research concerning geosciences and related disciplines in China, such as stratigraphy, paleontology, origin and history of the Earth, structural geology, tectonics, mineralogy, petrology, geochemistry, geophysics, geology of mineral deposits, hydrogeology, engineering geology, environmental geology, regional geology and new theories and technologies of geological exploration. Those of scientific interest to the geological community in China or of international interest are also welcome.
CHEN Danling , LIU Liang , SUN Yong , ZHANG Anda , ZHANG Chengli , LIU Xiaoming , LUO JinhaiKey Laboratory of Continental Dynamics , Ministry of Education , Department of Geology , Northwest University , Xi''''an , Shaanxi ,
2004, 78(1).
Abstract:The Shicaogou granite has been identified as a magnesian (Fe-number=0.71-0.76), calcic to calc-alkalic (MALI=3.84-5.76) and peraluminous (ASI=1.06-1.13) granite of the syn-collisional S-type, with high SiO2(>71%), A12O3 (>13%) and Na2O+K2O (6.28%-7.33%, equal for NaO2 and K2O). Trace element and REE analyses show that the granite is rich in LILE such as of Rb, Sr, Ba and Th, and poor in HFSE like Yb, Y, Zr and Hf. Its Rb/Sr ratio is greater than 1; the contents of Nb and Ta, and the ratio of Nb/Ta as well as the REE geochemical features (e.g. REE abundance, visible fractionation of LREE and HREE and medium to pronounced negative Eu anomalies) are all similar to those of crust-origin, continent-continent syn-collisional granite. Moreover, the granite exhibits almost the same pattern as that of the typical continent-continent syn-collisional granite on the spider diagram and all samples fall within the syn-collisional granite field.The cathodoluminescence (CL) investigations have revealed that the zircon f
LI Zilong , CHEN Hanlin , YANG Shufeng , DONG Chuanwan , XIAO Wenjiao , LI Jiliang , YE Ying , WANG JianDepartment of Earth Sciences , Faculty of Science , Zhejiang University , Hangzhou , Institute of Geology , Geophysics , Chinese Academy of Sciences , Beijing
2004, 78(1).
Abstract:Altay granulite (AG), which represents the product of high-grade metamorphism in the lower crust, was newly found in the Wuqiagou area, Fuyun County in the Altay orogenic belt, Northwest China. It is composed mainly of hypersthene, augite, basic plagioclase, amphibole and brown biotite. Its mineral compositions of amphibole and biotite are rich in Mg/(Mg+Fe2+) and Ti. Geochemically, the AG is enriched in Mg/(Mg+Fe2+) and A12O3, and poor in CaO, with depletion of U, Th, K and Rb contents. Furthermore, geochemical data reflect that the protolith of the AG is igneous-genetic calc-alkaline basalt formed under an island arc environment. The AG has ZREE of 92.38-96.58 ppm and enriched LREE model with weak positive Eu anomaly of 1.09-1.15. In the MORB normalized spider diagram, the AG shows tri-doming pattern with a strong negative Nb anomaly and medium negative P and Ti anomalies, reflecting that the AG has tectonic relation with subduction or subduction-related materials. The P-T conditions of peak metamorphi
ZHAO Lei , HAO Jinhua , DING Yifei , LIU Yulong China University of Geosciences
2004, 78(1).
Abstract:Based on studies of petrography, mineralogy and mineral chemistry, deep mantle fluids and their products in kimberlites and diamonds can be assorted into the ultradeep fluid-transmitted minerals with an oxygen-free feature, the deep fluid metasomatized-minerals characterized by enrichment in TiO2, K2O, BaO, REE and Fe3+, and the deep fluid-reformed minerals. The three types show a successive descent in fluid origin depth and metasomatism strength, and they have brought forth a series of corresponding metasomatic products.
WANG Zhimin , XU Bei , ZHOU Yaoqi , XU Hehua , HUANG Shaoying The Key Laboratory of Orogenic Belts , Crustal Evolution
2004, 78(1).
Abstract:Continent subduction is one of the hot research problems in geoscience. New models presented here have been set up and two-dimensional numerical modeling research on the possibility of continental subduction has been made with the finite element software, ANSYS, based on documentary evidence and reasonable assumptions that the subduction of oceanic crust has occurred, the subduction of continental crust can take place and the process can be simplified to a discontinuous plane strain theory model. The modeling results show that it is completely possible for continental crust to be subducted to a depth of 120 km under certain circumstances and conditions. At the same time, the simulations of continental subduction under a single dynamical factor have also been made, including the pull force of the subducted oceanic lithosphere, the drag force connected with mantle convection and the push force of the mid-ocean ridge. These experiments show that the drag force connected with mantle convection is critical for continent subduction.
Chief Editor:HOU Zengqian
Governing Body:China Association for Science and Technology
Organizer:Geological Society of China
start publication :1922
ISSN:ISSN 1000-9515
CN:CN 11-2001/P