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Petrogenesis and significance of early Yanshanian syenite-granite complex in eastern Nanling Range

Science china earth {2. 2005年第7期48卷 912-924页

作者： CHEN Peirong1, ZHOU Xinmin1, ZHANG Wenlan1, LI Huimin2. FAN Chunfang1, SUN Tao1, CHEN Weifeng1 & ZHANG Min1 1. State Key Laboratory of Mineral Deposits Research, department of earth {2., nanjing University, nanjing 2.0093, china 2. Tianjin Institute of Geology and Mineral Resources, china Geological Survey, Tianjin 300170, china State Key Laboratory of Mineral Deposits Research Department of Earth Sciences Nanjing University Nanjing 210093 China Tianjin Institute of Geology and Mineral Resources China Geological Survey Tianjin 300170 China

In the eastern Nanling Range there exists the early Yanshanian syenite-granite assemblage. A representative example is the Pitou-Tabei complex composed of the Tabei syenite pluton and the Pitou syenogranite pluton in southern Jiangxi Province. U-Pb zircon dating yields ages of 188.6±2.2.Ma for the Tabei pluton and 186.3±1.1 Ma for the Pitou pluton. The Tabei syenite is characterized by relatively low SiO2.content (62.40% - 68.75%), high alkalis (K2.+Na2. = 10.56%-11.96%), low percent K2./Na2. ratios (0.56-0.93), metaluminous fea- ture (A/CNK = 0.80-1.00), enrichment in LILE (Rb, Ba, K) and HFSE (Th, U, Nb, Ta, Zr, and so on), weakly negative to positive Eu anomalies (δ Eu = 0.63-1.82., relatively low (87Sr/86Sr)i (0.70412.0.70543), and relatively high ε Nd(t) (3.14-3.52.. The Pitou syenogranite is charac- terized by high silicon content (SiO2.= 71.06%-76.2.%), relatively low alkalis (K2.+Na2. = 8.10%-9.80%), high percent K2./Na2. ratios (1.2.-1.94), metaluminous feature (A/CNK = 0.94-1.07), enrichment in Rb, Th (U), K, depletion in Ba, Nb, Ta, Sr, P , Zr, Ti, high ΣREE (av- eraging 451.03 μg/g), strong negative Eu anomalies (δ Eu = 0.2.-0.33), relatively high (87Sr/86Sr)i (0.70805-0.70912., and relatively low ε Nd( t ) (?5.35-?6.2.). The Tabei syenite and Pitou syenogranite both have the characteristics of A-type granites. The former is considered to be from the asthenosphere mantle, and the latter was the product of the crust-mantle mixture. They both were probably formed in a rifting setting.

关键词： syenite-granite assemblage single zircon U-Pb age rifting environment Nanling Range.

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Distribution characteristics of terrestrial heat flow density in Jiyang depression of Shengli Oilfield, East china

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Science china earth {2. 2004年第9期47卷 804-812页

作者： GONG Yuling1,2. WANG Liangshu1, LIU Shaowen1, LI Cheng1, HAN Yongbing1, LI Hua1, LIU Bo1 & CAI Jingong3 1. department of earth {2., nanjing University, nanjing 2.0093, china 2. department of Exploration and Information Technology of East china Institute of Technology, Fuzhou 344000, china 3. earth Science Institution of Shengli Oilfield, Dongying 2.7015, china department of earth {2. Nanjing University Nanjing 210093 China department of Exploration and Information Technology of East china Institute of Technology Fuzhou 344000 China earth Science Institution of Shengli Oilfield Dongying 257015 China

Based on the geo-temperature data of 13 systematically continuous temperature log curves and 700 testing oil boreholes in Jiyang depression, Shengli Oilfield, and the measured thermal conductivities of 47 rock samples, the terrestrial heat flow densities of 114 boreholes of Jiyang depression and its surrounding areas are determined, including 13 of those data derived from systemically continuous temperature logging. The results show that Jiyang depression has a relatively high background heat flow with an average value (65.8 5.4) mW/m2. The lateral variation of heat flow in basin has negative correlation with basement depth. Moreover, heat flow of uplift areas with shallower basement is high, so are those of regions with volcanic rocks, and those of depression areas with deep basement are relatively low. The heat flow densities of different structural units of Jiyang depression can be summarized as follows: The average heat flow value of Zhanhua sag is (67.4 5.3) mW/m2. higher than that of the whole basin, that of Dongying sag is (66.0 6.1) mW/m2. and that of Chezhen sag is (65.1 3.7) mW/m2. It is apparent that these latter two values are approximate to the average value of the whole Jiyang depression, while the average value of Huimin sag is (63.65.0) mW/m2. lower than that of the whole basin. In fact, the basement depth and the distribution framework of uplift and depression areas are all controlled by the process of lithosphere extension. In addition, the distribution of volcanic rocks in basin is also relatively close to this extension geodynamic process. In summary, the distribution characteristics of terrestrial heat flow of Jiyang depression is determined by the Cenozoic tectono-thermal events of this region.

关键词： Jiyang depression, terrestrial heat flow, thermal conductivity.

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Paleomagnetic results of the Cretaceous marine sediments in Tongyouluke, southwest Tarim

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Science china earth {2. 2005年第3期48卷 406-416页

作者： SHEN Zhongyue1, CHEN Hanlin1, FANG Dajun1, DING Jinghai1, ZHANG Shiben2. HUANG Zhibin2.& LI Meng2.1. department of earth {2., Zhejiang University, Hangzhou 31002. china 2. Tarim Oil Field Company, Petrochina Company Limited, Korla 830011, china 1. department of earth {2. Zhejiang University 310027 Hangzhou China 2. Tarim Oil Field Company PetroChina Company Limited 830011 Korla China

Paleomagnetic and rock magnetic studies on samples of 18 sites from the Creta- ceous marine sedimentary rocks in the Tongyouluke section, Akto County, southwest Tarim, china show that the magnetic carriers of the Lower Cretaceous are dominated by hematite with some magnetite, while the magnetic carriers of the Upper Cretaceous are characterized by a combination of magnetite and titanomagnetite as well as hematite and goethite. Stepwise thermal demagnetization is performed and vector analysis is used to isolate magnetic components, which illustrates a single magnetic component or double magnetic components. The high temperature stable components are dual polarities and pass polarity test, reversal test and consistency test. The overall mean direction of the Lower Cretaceous is D = 2..0°, I = 42.0°, α95=6.5° with pole position at φ = 190.3°, λ=63.1°, dp=4.9°, dm=8.0°. The overall mean direction of the Upper Cretaceous is D = 2..1°, I = 39.4°, α95=11.2. with pole position at φ =190.9°, λ=60.3°, dp= 8.0°, dm=13.4°. Compared with the inclination of the Early Cretaceous from red beds of north Tarim, the contemporary inclination of southwest Tarim is 10.0°±7.8° sharper, but it is still 8.1° ±8.9°, shallower than that of Early Cretaceous basalts in southwest Tarim. Although these pa- leomagnetic data show slightly larger confidence limit, the paleolatitude of the marine Cretaceous tends to lie between that of terrestrial red beds and volcanic rocks.

关键词： Tarim paleomagnetism, Cretaceous, magnetic inclination, red beds, marine sedimentary rock.

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Identification of Hercynian shoshonitic intrusive rocks in central Hainan Island and its geotectonic implications

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Science Bulletin 2006年第20期51卷 2507-2519页

作者： XIE Caifu1, 2. ZHU Jinchu1, DING Shijiang3, ZHANG Yeming2. FU Tai’an2.& LI Zhihong2.1. State Key Laboratory for Mineral Deposits Research and department of earth {2., nanjing University, nanjing 2.0093, china 2. Yichang Institute of Geology and Mineral Resources, Yichang 443003, china 3. Hainan Bureau of Geology and Mineral Resources, Haikou 5702.6, china department of Otolaryngology University Hospital VU P.O. Box 7057 1007 MB Amsterdam The Netherlands State Key Laboratory for Mineral Deposits Research and department of earth {2. Nanjing University Nanjing 210093 China

An identification has been made of some shoshonitic intrusive rocks in central Hainan Island recently. These rocks are K-rich (K2.=2.9%―5.1%, K2./Na2.=0.95―2.12., distinctly enriched in LILE and LREE, strongly depleted in Nb, Ta, and moder- ately depleted in Sr and Ti, with (87Sr/86Sr)i = 0.70859―0.7142. and ε Nd(t) = (?2.77―?7.49). They were derived from an EMⅡ-type mantle source. The enrichment process is related to metasomatism of depleted mantle caused by a great amount of fluid-melt released from oceanic crust and terri- genous sediments at great depth (eclogite facies) during the subduction of the South china plate under the Indochina-South china Sea plate in the Carbon- iferous–Early Permian. A SHRIMP U-Pb zircon dating yields a crystallization age of 2.2.7 Ma for the sho- shonitic intrusions, which is coeval with the strongly peraluminous granites found in central Hainan Island. These two kinds of rocks generally possess syn-intrusion ductile deformation structures. Thus they are considered to have been generated during the early stage (syn-thrust phase) of a post-collisional event. The primary magma of shoshonitic rocks was produced at a depth > 80 km by decompression- dehydration melting of previously enriched litho- spheric mantle wedge, phlogopite-bearing garnet peridotite, which was in turn caused by the break-off of a descendent slab and upwelling of a hot as- thenosphere. The rising of melts was accompaniedby crustal contamination and crystallization fractiona- tion (AFC). Combining with other related data, it is proposed that the southwards subduction and amal- gamation of the South china plate with the Indo- china-South china Sea plate took place at ca. 2.7- 2.8 Ma, which was a part of the convergence proc- ess of the Pangea supercontinent. The suture zone was probably located along the line of Song Ma-Beibu Gulf-north margin of the Yunkai Moun- tains-Wuyi Mountains.

关键词： SHRIMP U-Pb dating Hercynian shoshonitic intrusive rocks post-collisional event enriched mantle Hainan Island.

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Depth zonation of Arenigian acritarchs in South china

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Chinese Science Bulletin 1997年第3期42卷 248-251页

作者： XU Wanhongdepartment of earth {2., nanjing University, nanjing 2.0093, china department of earth {2. Nanjing University Nanjing China

STAPLIN revealed that palaeoenvironment changes seem to control acritarch distribution patterns. However, scientists have been puzzled by the fact that characteristic offshore acritarchs occur with nearshore ones. This note demonstrates depth zonation of Arenigian acritarchs in South china and reveals the variation of water depth in South china during the Arenig Age.

关键词： South china Arenigian acritarch depth zonation.

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Prediction analysis of long-term memory effect for calamity gray series

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Science china earth {2. 2004年第3期47卷 209-220页

作者： CHEN Zhaonan (CHEN Chaonan)1 & LI Zongyang (LEE Tzongyeang)2.1. department of earth {2., National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan, china 2. department of Information Management, Leader University, No. 188, Sec 5, Au-Chung Road, Tainan 70901, Taiwan, china Leader Univ Dept Informat Management Tainan 70901 Taiwan Natl Cheng Kung Univ Dept Earth Sci Tainan 70101 Taiwan

It is adequate to use the gray theory for modeling and forecasting short-term calamity series. The forecast of calamity gray series is equivalent to predicting an extraordinary event in nature. In order to look for the regularity, the calamity date series, created from the threshold for a fixed time-interval series, are studied. In this paper, the Hurst exponent is applied to defining the long-term memory effect of the simulated calamity series, and is tested for the feasibility of using it as pre-requisite information before the gray modeling and forecasting. Based on the fractional Brownian motion (fBm) model, the time series with a definite length or quantity of data are derived assuming that various kinds of memory effect exist. Different threshold values are defined to yield or to analogize the calamity date series that are required in the prediction of the gray calamity events. After case study, both of the simulated and real seismic data show that the Hurst exponents are greater than 0.5 and, therefore, indicate that the long-term memory ef-fect exists. The correlation between the Hurst exponent and the gray modeling parameter, a, provides criteria for the classification of the forecast.

关键词： gray theory, calamity series, Hurst exponent, long-term memory effect, fractional Brownian motion.

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Holocene grassland vegetation, climate and human impact in central eastern Inner Mongolia

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Science china earth {2. 2005年第7期48卷 1025-1039页

作者： HUANG Fei1, Kealhofer Lisa2. XIONG Shangfa3 & HUANG Fengbao1 1. nanjing Institute of Geology and Paleontology,Chinese Academy of sciences,nanjing 2.0008,china 2. Anthropology and Sociology department,Santa Clara University,CA 95053,USA 3. Institute of Geology and Geophysics,Chinese Academy of sciences,Beijing 10002.,china nanjing Institute of Geology and Paleontology Chinese Academy of Sciences Nanjing 210008 China Anthropology and Sociology department Santa Clara University CA 95053 United States Institute of Geology and Geoohysics Chinese Academy of Sciences Beijina 100029 China

Phytolith and pollen preserved in the Taipusi Banner paleosol profile, central eastern Inner Mongolia, provide evidence of Holocene grassland vegetation, climate and human impact. The combined phytolith and pollen records reveal a major change in vegetation composition about 5000 a BP. Before 5000 a BP, the vegetation was dominated by Aneurolepidium Chinese-Stipa grandis grassland of C4 grasses. After 5000 a BP, C4 grasses rapidly retreated, indicating a shift to colder and more arid conditions. The gradual invasion of Stipa krylovii, Ag-ropyron desertorum, Ephedra, Chenopodiaceae and Caragana reveal the onset of grassland degeneration. Between 10000 and 872. a BP, the Aneurolepidium Chinese-Stipa grandis grassland included a small proportion of Artemisia shrub and Echionopos type plants, implying a strong winter monsoon and very weak summer monsoon. From 872. to 7000 a BP, C4 grasses were common, indicating a strengthening of the summer monsoon. Between 7000 and 5000 a BP, the Holocene thermal maximum was evident, with a significant expansion of C4 grasses and the presence of some trees (such as Pinus and Betula, and so on) in or near the study site. From 42.0?000 a BP, a sandy grassland of Artemisia and Agropyron desertorum together with Aster-type taxa occurred. Precipitation amelioration took place between 3000 and 2.70 a BP, with a rapid development of Echinops type plants and a small expansion of C4 grasses. From 2.70 a BP to present, human activities accelerated the process of grassland degeneration.

关键词： phytolith and pollen records grassland environment change human impact Holocene central eastern Inner Mongolia.

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Dehydration melting of solid amphibolite at 2.0 GPa: Effects of time and temperature

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Science china earth {2. 2005年第8期48卷 1120-1133页

作者： ZHOU Wenge1, XIE Hongsen1, LIU Yonggang1, ZHENG Xiaogang1, ZHAO Zhidan2.& ZHOU Hui3 1. Laboratory of Material in the earth’s Interior, Institute of Geochemistry, Chinese Academy of sciences, Guiyang 550002.{2. 2. department of Geology,{2. University of Geosciences, Beijing 100083,{2. 3. department of Geology, Peking University, Beijing 100871,{2. 1. Laboratory of Material in the earth’s Interior Institute of Geochemistry Chinese Academy of Sciences 550002 Guiyang China 2. department of Geology China University of Geosciences 100083 Beijing China 3. department of Geology Peking University 100871 Beijing China

Two sets of dehydration-melting with a natural solid amphibolite, collected from North Himalayan structure zone, Tibet, have been carried out in multi-anvil apparatus at 2.0 GPa and 800―1000℃, for 12.2.0 h. One is keeping the pressure at 2.0 GPa and the annealing time of 12.h, changing the temperature (800―1000℃). The other is keeping the pressure at 2.0 GPa and temperature at 850℃, varying the annealing time (12.2.0 h). The products are inspected with microscope and electron probe. The results indicate that at 2.0 GPa, annealing time of 12.h, garnets, melts and clinopyroxenes occur in amphibolite gradually with increasing temperature and the chemical compositions of melt vary from tonalite to granodiorite, and then to tonalite. However, at 2.0 GPa and 850℃, with the annealing time increasing, the garnets, melts and cli-nopyroxenes also occur in amphibolite gradually and the chemical compositions of melt vary from tonalite to granodiorite. In both cases, melts interconnect with each other when the contents of melt are over the 5 vol.%. the viscosities of the melt produced in amphibolite at temperature higher than 850℃ are on a level with 104 Pa·s. The interconnected melt with such a viscosity may segregate from the source rock and form the magma over reasonable geological time. Therefore, it is believed that at the lower part of the overthickened crust, the tonlitic and grano-dioritic magma may be generated through the dehydration melting of amphibolite.

关键词： solid amphibolite, high pressure, high temperature, time, partial melting.

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Discovery of a pterodactylid pterosaur from the Yixian Formation of western Liaoning,china

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Chinese Science Bulletin 2001年第13期46卷 1112-1117页

作者： WANG Xiaolin & LU Junchang1. Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of sciences, Beijing 100044, china 2. College of {2. sciences and Resources, china University of Geo-sciences, Beijing 100083, china 3. department of Geological sciences, Southern Methodist University, Dallas, TX 752.5, USA Institute of Vertebrate Paleontology Chinese Academy of Sciences Beijing 100044 China

A well-preserved pterosaur with nearly complete skull is described from the Lower Cretaceous Yixian Formation at Sihetun in western Liaoning. It is characterized by a low and long crestless skull, slender and pointed teeth, long metacarpal, nearly equal length of metatarsals I -III and short pedal digit V. It is referred to a new genus and species of the family Pterodactylidae: Haopterus gracilis gen. et sp. nov. This is the first pterosaur with a nearly complete skull from the Jehol Biota; it also represents the first non-controversial fossil record of Pterodactylidae in Asia. Haopterus is more derived than Pterodactylus from the Late Jurassic Solnhofen in Germany. This discovery extends the distribution of the family Pterodactylidae from Europe and Africa to Asia and its latest occurrence from the Late Jurassic to the Early Cretaceous. The discovery of Haopterus gracilis provides further evidence for the study of the originand radiation of the Jehol Biota; it also sheds new light on the evolution and

关键词： western Liaoning Early Cretaceous Yixian Formation Pterodactylidae.

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Early J_2.basalts in SE china:Incipience of large-scale late Mesozoic magmatism

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Science china earth {2. 2006年第8期49卷 796-815页

作者： XIE Xin1, XU Xisheng1, ZOU Haibo2. JIANG Shaoyong1, ZHANG Ming3 & QIU Jiansheng1 1. State Key Laboratory of Mineral Deposit Research, department of earth {2., nanjing University, nanjing 2.0093, china 2. department of earth and Space {2., University of California at Los Angeles, Los Angeles, CA90095-1567, USA. 3. GEMOC ARC National Key Centre, department of earth and Planetary {2., Macquarie University, Sydney, N.S.W. 2.09, Australia 1. State Key Laboratory of Mineral Deposit Research Department of Earth Sciences Nanjing University Nanjing 210093 China 2. department of earth and Space {2. University of California at Los Angeles Los Angeles CA90095-1567 USA 3. GEMOC ARC National Key Centre Department of Earth and Planetary Sciences Macquarie University Sydney N.S.W. 2109 Australia

Magmatism in SE china was dormant during 2.4―180 Ma, but was reactivated in 180― 170 Ma (early J2., and then became more and more intensive towards the end of early Cretaceous. The small-scale early J2.magmatism is the incipience to long-term and large-scale magmatism in this region. A near east-west (EW) trend volcanic belt was distributed across south Hunan, south Jiangxi and southwest Fujian was formed during early J2.time. Along this belt from the inland toward the coast, the lithology of basalts changes from alkali into tholeiite, and the amount of erupted volcanic rocks and the proportions of rhyolites coexisting with the basalts increase. On the basis of geochemical char- acteristics of these basalts, we infer that the melting degree of source rocks and the extent of frac- tional crystallization and crustal contamination all increased whereas the depth of mantle source de- creased from the inland to the coast, which led to the variations of geological characteristics of the volcanic belt. In early J2. the western spreading Pacific plate began to subduct underneath SE china continental block, reactivating near EW trend deep fault that was originally formed during the Indos- inian event. The stress of the western spreading Pacific plate and the extent of asthenosphere up- welling increased from the inland to the coast, which is consistent with the generation and evolution of early J2.basalts.

关键词： early J2 basalts, upwelling of asthenosphere, large-scale magmatism, SE china, the Pacific plate.

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