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Rock magnetic studies on the hominoid-bearing sediments at Zhupeng, Yuanmou Basin, southwestern China and its paleoclimatic significance

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Science Bulletin 2005年第15期 119-126页

作者： YAO Haitao1, LIU Qingsong1,2. Lü Lianqing1, CHANG Zhigang1 & ZHU Rixiang1 1. Paleomagnetism Laboratory, institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 10002., China 2. institute of Geophysics and {2. Geophysics, university of cali-fornia, santa cruz, ca 95064, usa

It has been proposed that paleoclimatic changes and tectonic events strongly affect hominoid evolution. The Zhupeng section at Yuanmou Basin, southwestern China, with the hominoid-bearing fluvial-lacustrine sediments, is an ideal natural laboratory to test this hypothesis. This study provided an integrated magnetic study, including low-fre- quency susceptibility, the anisotropy of magnetic susceptibil-ity, temperature-dependent susceptibility, hysteresis loops, isothermal remanent magnetization, and anhysteretic rema-nent magnetization, on samples from the Baozidongqing section at Zhupeng. Results show that the dominant mag-netic carrier is hematite, with minor amount of magnetite. Both the composition and concentration of magnetic miner-als strongly correlate with the lithostratigraphy. At least eight short-term events defined by higher concentrations of magnetite were identified. These short events reflect that the subtropical dry-hot climate is similar to today’s climate. Basing on the lithostratigraphic and rock magnetic results, we suggest that Yuanmou Basin was in a steady deposition environment from about 11 to 7 Ma, which is characterized by alternating of long-term torrid-humid climate and short-term dry-hot climate. Our study provides invaluable environment information for understanding the climate shift and the relationship between paleoenvironment and homi-noid evolution in southwestern China during late Miocene.

关键词： Yuanmou Basin hominoid late Miocene rock magnet-ism paleoclimate.

carbon isotopic characteristics and their genetic relationships for individual lipids in plants and sediments from a marsh sedimentary environment

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Science China Earth Sciences 2005年第8期48卷 1203-1210页

作者： DUAN Yi1, ZHANG Hui1, ZHENG Chaoyang1, WU Baoxiang1 & ZHENG Guodong2.1. Lanzhou institute of Geology, Chinese Academy of Sciences, Lanzhou 730000, China 2. Department of Earth & planetary System Science, Graduate School of Science, Hiroshima {2., Higashi-Hiroshima 739-85Japan 1. Lanzhou institute of Geology Chinese Academy of Sciences 730000 Lanzhou China 2. Department of Earth & planetary System Science Graduate School of Science Hiroshima University 739-8526 Higashi-Hiroshima Japan

The carbon isotopes of individual lipids in herbaceous plants and tree leaves in Ruoergai marsh were measured by the GC-IRMS analytical technique in order to understand the inherent relationships of carbon isotopes between sedimentary and plant lipids from typical marsh environment. The analytical results show that the carbon isotopic compositions of n-alkanes in different kinds of plants differ significantly. Mean δ 13C values of n-alkanes in her-baceous plants (?32.2.―?36.9‰) are 3.3‰ lower than those in woody plant (?2..2.― ?35.0‰). The carbon isotopic compositions of fatty acids in organisms (?30.3‰― ?36.2.) are very similar to those of n-alkanes and the δ 13C values for unsaturated fatty acids are within the range of those for saturated fatty acids. The differences in δ 13C values between plant lipids are obvious and range from 2.4‰ to 7.8‰. It is observed that the carbon isotopic compositions of sedimentary lipids are closely related to those of plant lipids. The carbon isotopic compositions (?2..0‰―?36.9‰) of n-alkanes, ≥C16 fatty acids, n-alkanols, sterols and n-alkanones in the sediments are similar to those of plant lipids and the carbon isotopic compositions of short-chain sedimentary lipids are similar to those of long-chain sedimentary homologues. These indicate that the sedimentary lipids are derived from high plants. However, the δ 13C values of C14:0 and C15:0 fatty acids in the sediments are lighter than those of the same carbon number saturated homologues in plants, reflecting the genetic features partially derived from bacteria. These data provide scientific evidence for carbon isotope-applied research of individual lipids.

关键词： marsh environment, plants, sediments, individual lipids, carbon isotopic compositions, genetic relationships.

LOW TEMPERATURE DATING OF HIGH MOUNTAIN ROCKS:(U-Th)/He AGES FROM HIGHER HIMALAYAN SAMPLES, EASTERN NEPAL

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地学前缘 2000年第S1期7卷 16-17页

作者： Mary Hubbard 1, Martha House 2.1 Dept. of Geology, Thompson Hall, Kansas State university, Manhattan, KS 66506 usa 2.Division of Geological and {2. Sciences, california institute of Technology, Pasadena, ca 9112. usa)

Recently the (U\|Th)/He method on apatite has been applied to studies of cooling and exhumation in mountain belts in order to place constraints on the low temperature cooling history (Wolf et al., 1997; House et al., 1998). Because the closure temperature of the method is 65～75℃, it provides useful information regarding the exhumation of rocks through the upper few kilometers of the earth’s crust. When the (U\|Th)/He method is coupled with methods such as 40 Ar/ 39 Ar with higher closure temperatures (2.0～500℃), a cooling history can be reconstructed over a wide range of temperatures. In eastern Nepal, in the Dudh Kosi valley a suite of samples from the Main Central Thrust (MCT) to the middle of the Higher Himalayan section was previously dated using 40 Ar/ 39 Ar on K\|feldspar, biotite, muscovite, and hornblende (Hubbard and Harrison,1989). We have applied the (U\|Th)/He method to apatite from these same samples. The structurally highest site, Ngozumba, is in the middle to upper part of the Higher Himalaya in the Gokyo valley. At Ngozumba previous 40 Ar/ 39 Ar ages include: muscovite at (16 6±0 4)Ma (closure temperature (CT)350℃), biotite at (16 8±1 4)Ma (CT 300℃), and K\|feldspar at (15 5±1 8)Ma (CT 2.0℃).The apatite age for an augen gneiss from this location was (6 3±3 8)Ma suggesting slower cooling for that part of the range during the last 15Ma. Structurally below Ngozumba, in the MCT zone, 40 Ar/ 39 Ar ages include:(2. 9±0 2.Ma for hornblende (CT 500℃), (12.0±0 2.Ma for muscovite, and (8 0±0 2.Ma for K\|feldspar (CT 2.0℃). The apatite age obtained for a biotite schist at this location was (4 6±0 2.Ma and is consistent with relatively constant cooling since 12.a. In between the MCT and the Ngozumba site samples were collected near the settlement of Ghat that yielded anomalously young 40 Ar/ 39 Ar ages:(7 7±0 4)Ma for muscovite, (7 5±0 6)Ma for biotite, and (3 6±0 2.Ma for K\|feldspar (CT 2.0℃). The apatite age is consistent with these young ages at (0 8±0 1)Ma.

关键词： U\|Th)/He dating exhumation Himalaya Nepal cooling history

Dynamical framework with blocking topography coordinates for atmospheric GCM and its validation

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Chinese Science Bulletin 2003年第S2期48卷 9-17页

作者： LIN Zhaohui~1, ZHANG Ming~(1,2., LIANG Danqing~(1,2. WANG Aihui~1, ZHANG Dongling~1 & ZENG Qingcun~1 1. ICCES, institute of Atmospheric Physics, Chinese Academy of Sciences. Beijing 10002.. China 2. College of Meteorology. PLA university of Science and Technology, Nanjing 2.1101. China Chinese Acad Sci Inst Atmospher Phys ICCES Beijing 100029 Peoples R China PLA Univ Sci & Technol Coll Meteor PLA Nanjing 211101 Peoples R China

The dynamical framework with Blocking To-pography Coordinates (hereafter, BTC), which is suited tohandle the steep topography for the atmospheric generalcirculation models, is presented in this paper, together withits validation results. The integral properties of both the dif-ferential and finite-difference equations for the BTC dy-namical core are: gross mass conservation, quadratic con-servation for advection terms, Coriolis force does not changethe kinetic energy, conservation of total available energy. Theimproved nonlinear iteration scheme is utilized for thetime-integration. The energy conservation for BTC dynami-cal core is validated by using the integration results from9-layer and 2.-layer version respectively. Comparison resultsshow that, the changes of the kinetic energy and total avail-able potential energy during the integration are quite closefor both the BTC dynamical framework and the dynamicalframework of IAP 9-level and IAP 2.-level AGCM, and thismay suggest that the BTC dynamical core can be used forlong-term integration with good computational ***, the BTC dynamical core has the advantageover the terrain following (sigma) coordinates in its betterrepresentation of the influence of the large-scale topographyon the atmospheric general circulation. Finally, the correct-ness and reasonableness of the BTC dynamical core has beenfurther proved by the numerical simulation of the topogra-phy influence on the quasi-stationary planetary wave with2.-layer version of BTC dynamical framework.

关键词： blocking topography coordinates atmospheric general circulation model dynamical framework.

Tectonic evolution of the Dabieshan orogen: In the view from polyphase deformation of the Beihuaiyang metamorphic zone

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Science China Earth Sciences 2005年第7期48卷 886-899页

作者： LIN Wei1, 2. Faure Michel3, WANG Qingchen1 & Arnaud Nicolas4 1. LTE, institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 10002., China 2. Department of Earth and planetary Sciences, Graduate School of Science, Nagoya {2., Japan 3. ISTO, UMR CNRS 6113, Batiment Géosciences, Orléans Université d’Orléans, 45067 Orléans Cedex 2. France 4. UMR 652. "Magmas et Volcans", 5 Rue Kessler, 63000 Clermont-Ferrand, France LTE Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China Department of Earth and planetary Sciences Graduate School of Science Nagoya University Japan ISTO UMR CNRS 6113 Orléans Université d'Orléans 45067 Orléans Cedex 2 France UMR 652. Magmas et Volcans 63000 Clermont-Ferrand 5 Rue Kessler France

The Beihuaiyang metamorphic zone was formed by the Early Mesozoic collision of the North and South China Blocks. It consisted of the Foziling and Luzhenguan complexes and was thought to have never afforded a deep subduction. A similar feature of the deformation in the Dabieshan UHP metamorphic rocks implies that these different tectonic units share the same geodynamic background. The early stage of deformation can be preserved on account of their relatively shallower subduction than that for UHP rocks. On the basis of an analysis of the geo- logical structure and geochronological results, five deformational stages have been recognized: a D1-Early compressional deformation which represents the continental subduction; a D2.Early exhumation deformation producing a syn-convergence exhumation; a D3-Main deformation, represented by an exhumation deformation with Late Triassic age; a D4-Doming and its margin extensional gravity collapse deformation and finally a D5-regional extensional deformation of Cretaceous that was mostly introduced by the migmatization and plutonism.

关键词： Beihuaiyang metamorphic zone geometry kinematic polyphase deformation tectonic evolution.

A new high-precision furnace for paleomagnetic and paleointensity studies:minimizing magnetic noise emanating from heater-currents inside traditional thermal demagnetizers

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A new high-precision furnace for paleomagnetic and paleointe...

Limitations of absolute current densities derived from the Semel & Skumanich method

中国地球物理学会第二十六届年会、中国地震学会第十三次学术大会

作者： Zhong Zheng~1,Xixi Zhao~2.1 Geoscience Division,Sogokaihatsu Co,Ltd.,Nishi -Koiwa 1 -30- 16, Edogawa - ku,Tokyo 133 - 0057,Japan 2.institute of Geophysics and planetary Physics,{2. of california,santa cruz,ca 95064,usa

Demagnetization is one of major lab measurements to recognize and remove secondary magnetization,and is routinely performed in paleomagnetic laboratories using thermal demagnetizers to heat specimens to specified temp... 详细信息

关键词： A new high-precision furnace for paleomagnetic and paleointensity studies:minimizing magnetic noise emanating from heater-currents inside traditional thermal demagnetizers

来源： cnki会议评论

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cnki会议

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Science China(Physics,Mechanics & Astronomy) 2009年第11期52卷 1678-1685页

作者： LI Jing1 & FAN YuHong2.1 institute for Astronomy, university of Hawaii, 2.80 Woodlawn Drive, Honolulu, HI 9682.,{2. 2.High Altitude Observatory, Earth and Sun Systems Laboratory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307,{2. institute for Astronomy University of Hawaii 2680 Woodlawn Drive Honolulu HI 96822 USA High Altitude Observatory Earth and Sun Systems Laboratory National Center for Atmospheric Research P.O. Box 3000 Boulder CO 80307 USA Present address: UCLA institute of Geophysics and planetary Physics 2713 Geology Building MG 951567 Los Angeles CA 90095-1567 USA

Semel and Skumanich proposed a method to obtain the absolute electric current density, |Jz|, without disambiguation of 180° in the transverse field directions. The advantage of the method is that the uncertainty in the determination of the ambiguity in the magnetic azimuth is removed. Here, we investigate the limits of the calculation when applied to a numerical MHD model. We have found that the combination of changes in the magnetic azimuth with vanishing horizontal field component leads to errors, where electric current densities are often strong. Where errors occur, the calculation gives |Jz| too small by factors typically 1.2.- 2.0.

关键词： numerical MHD model magnetic field electric current density

High frequency complex permeability of flake-shaped Fe_(74)Cr_2.o_2.n_2._(10)Si_4B_4C_2.particle composite material

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Science China(Technological Sciences) 2010年第4期53卷 1056-1059页

作者： LIU KaiHuang1,LIU TianCheng1,2.LI JianLiang1,2.ZHANG Liang1,2.ZHANG HongHao1,2.LI DeRen1,2.LU ZhiChao1,2.& ZHOU ShaoXiong1,2.1 China Iron and Steel Research institute,Beijing 100081,China 2.Advanced Technology and Materials Co.,Ltd.,Beijing 100081,China 1. China Iron and Steel Research institute Beijing 100081 China2. Advanced Technology and Materials Co. Ltd. Beijing 100081 China

A composite consisting of flake-shaped Fe74Cr2.o2.n2.10Si4B4C2.particles was *** flake-shaped particles included in the composite were prepared by planetary ball *** complex permeability of the composite material was measured at frequency range from 10 MHz to 8.5 *** permeability of the composite containing flake-shaped particles was much higher than that of the spherical *** permeability of particles was improved by means of *** contrast to the random-spatial-distributed flake-shaped particle composites,the oriented-distributed ones had a higher effective permeability.A model was proposed considering the orientation ratio,and our calculation agreed well with the experimental data.

关键词： complex permeability composite materials flake-shaped electromagnetic wave absorber

Beamlet migration for complex structure and local angle-domain analysis

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Beamlet migration for complex structure and local angle-doma...