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Grain-size features of a Miocene loess-soil sequence at Qinan: Implications on its origin

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Science China Earth sciences 2006年第7期49卷 731-738页

作者： QIAO Yansong1,3, GUO Zhengtang2.1, HAO Qingzhen1, YIN Qiuzhen1, YUAN Baoyin1 & LIU Tungsheng1 1. institute of {1. and Geophysics,{2., Beijing 1.002., China 2. institute of Earth Environment,{2., Xi’an 710075, China 3. institute of Geomechanics, chinese academy of Geological sciences, Beijing 100081, China 1. institute of {1. and Geophysics Chinese Academy of Sciences Beijing 100029 China 3. institute of Geomechanics Chinese Academy of Geological Sciences Beijing 100081 China 2. {1. of Earth Environment Chinese Academy of Sciences Xi’an 710075 China

In this study, grain-size of 507 bulk samples from the QA-I Mioceneloess-soil sequence at Qinan were analyzed, and the grain-size features are compared with those oftypical Quaternary loess and soil samples, representative lacustrine and fluvial samples. Theresults indicate that the grain-size distribution pattern of the Miocene loess is essentiallysimilar to that of Quaternary loess, but greatly differs from the lacustrine and fluvial *** layers are regularly coarser than soil layers, indicating cyclical climate changes. Mediangrain-size along the 2.3.1.m sequence varies from 6 to 1. μm and the > 63 μm fraction representsonly 5.3% in maximum, 0.9% in average. Long-term grain-size variations are consistent with the loessaccumulation rate at Qinan and with the eolian mass accumulation rate in the North Pacific. Thesefeatures firmly indicate an eolian origin of the studied sequence, and also reveal a coeval changesbetween the long-term changes of eolian grain-size and continental aridity in the dust sourceregions.

关键词： Qinan, Miocene loess-soil sequence, grain-size, eolian origin.

Forcing mechanism of the Pleistocene east Asian monsoon variations in a phase perspective

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Science China Earth sciences 2005年第10期48卷 1708-1717页

作者： TIAN Jun1.2. WANG Pinxian1. CHENG Xinrong1. WANG Rujian1.& SUN Xiangjun1.3 1. State Key Laboratory of Marine {1., Tongji University, Shanghai 2.0092. China {1. and Geophysics,{2., Beijing 1.002., China 3. institute of Botany,{2., Beijing 1.0093, China State Key Laboratory of Marine geology Tongji University Shanghai China institute of {1. and Geophysics{2. Beijing China institute of Botany{1. Beijing China

The deep sea records from the ODP Sites 1.43 and 1.44 in the northern and southern South China Sea (SCS), including foraminiferal δ 1.O and δ 1.C, Opal% and pollen percentage, reveal that the variations of the east Asian monsoon have been closely correlated with the variations of the Earth’s orbital parameters (eccentricity, obliquity and precession) and the global ice volume on orbital scale. All the monsoonal proxies show strong 1.0 ka, 41.ka and 2. ka cycles. Although G. ruber δ 1.C of Site 1.43 is coherent with the ETP (ETP= normalized (eccentricity + obliquity-precession) at eccentricity, obliquity and precession bands, most of the coherent relationship focuses on the precession band, and the other monsoonal proxies are coherent with the ETP only at the precession band, which indicate that precession dominates the Pleistocene tropical climate changes. The phase relationship of the monsoonal proxies with the foraminiferal δ 1.O implies that the global ice volume changes have played a significant role in modulating the east Asian monsoon climate, at least dominating the winter monsoon. This forcing mechanism of the east Asian monsoon is apparently different from that of the Indian ocean mon-soon. The variations of the east Asian monsoon at the precession band, at least that of the winter monsoon, have been controlled not only by the sensible heating but also by the latent heating of the surface water in the South China Sea.

关键词： South China Sea, ODP, east Asian monsoon, orbital forcing, global ice volume.

Transient species and its properties of melatonin

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Science China Chemistry 2006年第4期49卷 308-314页

作者： ZHU Hongping1.2. ZHANG Zhaoxia1.2. ZHAO Hongwei1. WANG Wenfeng1.& YAO Side1.1. Shanghai institute of Applied Physics,{1., Shanghai 2.1.00, China 2. Graduate University of the{1., Beijing 1.0049, China 1. Shanghai institute of Applied Physics Chinese Academy of Sciences Shanghai 201800 China 2. Graduate University of the{1. Beijing 100049 China

The photo-physical and photo-chemical properties of melatonin (ML) werestudied by 2.6 nm laser flash photolysis (LFP). ML undergoes photo-ionization to produce radicalcation of ML (ML^(·+))and hydrated electrons (e_(aq)^-), while excited triplet state ~3ML~* is alsoformed during photolysis. The oxidation via one electron transfer from ML to SO_4^(·+) and thetriplet state of riboflavin (~3RF~*) has been also investigated and the rate constants for theprocess have been determined to be 8.0x1.^9 and 1.4x1.^9 L·mol^(-1.·s^(-1. respectively. Theradical cation of 2.2.'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS^(·+)) scavengingcapacities of melatonin and other antioxidants are compared in this paper.

关键词： melatonin, laser flash photolysis, photoionization, triplet state.

Gasdynamic characteristics of toroidal shock and detonation wave converging

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Science China(Physics,Mechanics & Astronomy) 2005年第6期48卷 739-749页

作者： TENG Honghui1.2.& JIANG Zonglin2.1. Key Laboratory of High Temperature Gas Dynamics, institute of Mechanics, {1. {2. of Sci- ences, Beijing 1.0080, China 2. Graduate University of chinese academy of sciences, Beijing 1.0039, China 1. Key Laboratory of High Temperature Gas Dynamics Institute of Mechanics Chinese Academy of Sciences 100080 Beijing China 2. Graduate University of{1. 100039 Beijing China

The modified CCW relation is applied to analyzing the shock, detonation wave converging and the role of chemical reactions in the process. Results indicate that the shock wave is strengthened faster than the detonation wave in the converging at the same initial Mach number. Euler equations implemented with a detailed chemical reaction model are solved to simulate toroidal shock and detonation wave converging. Gasdynamic characteristics of the converging are investigated, including wave interaction patterns, observable discrepancies and physical phenomena behind them. By comparing wave diffractions, converging processes and pressure evolutions in the focusing area, the different effects of chemical reactions on diffracting and converging processes are discussed and the analytic conclusion is demonstrated through the observation of numerical simulations.

关键词： converging, CCW relation, shock wave, detonation wave.

Isotopic feature and uranium dating of the volcanic rocks in the Okinawa Trough

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中国科学：地球科学英文版 2006年第4期49卷 375-383页

作者： HUANG Peng1,2. LI Anchun1, HU Ningjing2.3, FU Yongtao1& MA Zhibang4 1. institute of Oceanology,{1., Qingdao 2.6071, China 2. Graduate School of the{1., Beijing 100039, China 3. institute of Soil Science,{1., Nanjing 2.0008, China 4. institute of geology and Geophysics,{1., Beijing 1.002., China 1. institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China 2. Graduate School of the{1. Beijing 100039 China 3. institute of Soil Science Chinese Academy of Sciences Nanjing 210008 China 4. institute of {1. and Geophysics Chinese Academy of Sciences Beijing 100029 China

Volcanic rocks from the northern and middle Okinawa Trough were dated by ura- nium-series dating method. Differential fractions using magnetic procedure were designed to separate samples. New report on the ages and isotopic data of rocks in the northern trough (especially black pumice) was discussed. Based on the uranium dates and Sr-Nd isotopic ratio, magmatic evolution process of the Okinawa Trough was noted. Firstly, there have been wide silicic volcanic activities in the Okinawa Trough from late Pleistocene to present, and the volcanic rocks can be divided into three subgroups. Secondly, magma generally came from PREMA source area under the Okinawa Trough. Magmatic evolution in the northern trough was similar to the middle, but different to the south. Finally, volcanic activities indicated that opening of the southern Okinawa Trough did not happen due to the collision between Luson Arc and Eurasian Plate until the early Pleistocene.

关键词： Okinawa Trough, black pumice, uranium-series dating, Sr-Nd isotopic ratio, magmatic evolution.

Simulating the impacts of climate variation and land-cover changes on basin hydrology: A case study of the Suomo basin

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Science China Earth sciences 2005年第9期48卷 1501-1509页

作者： CHEN Junfeng1.2. LI Xiubin2.& ZHANG Ming2.1. institute of Remote Sensing & GIS, Peking University, Beijing 1.0871. China 2. institute of Geographical {2. and Natural Resources Research, chinese academy of sciences, Beijing 1.01.1. China 1. institute of Remote Sensing & GIS Peking University 100871 Beijing China 2. {1. of Geographical {1. and Natural Resources Research Chinese Academy of Sciences 100101 Beijing Chin

Impacts of land cover changes on watershed hydrology have been a long-term academic concern with acute dispute. But little attention has been paid to such effects on mesoscale river basins, where the society has a closer link to river hydrology. The present study focuses on a mesoscale river basin, the Suomo Basin that is located on the upper reaches of the Yangtze River. Land covers in the basin in the years 1.70, 1.86 and 1.99 were mapped. A lumped hydrologic model, CHARM, and a distributed hydrologic model, SWAT, were used to model the impacts of both land-cover change and climate variation on river runoff during the past four decades. The results show that the contribution of climate variation to the change of runoff regime makes up 60%―80%, while that of land cover changes only 2.%.

关键词： climate variation, land-cover changes, Suomo Basin, CHARM model, SWAT model.

Characteristics of chlorine isotope distribution and analysis on sylvinite deposit formation based on ancient salt rock in the western Tarim Basin

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Science China Earth sciences 2005年第11期48卷 1913-1920页

作者： TAN Hongbing1.2. MA Haizhou1. XIAO Yingkai1. WEI Haizhen1.2. ZHANG Xiying1.& MA Wandong1.1. institute of Salt Lakes,{1., Xining 81.008, China 2. Graduate School of the{1., Beijing 1.0039, China 1. institute of Salt Lakes Chinese Academy of Sciences 810008 Xining China 2. Graduate School of the{1. 100039 Beijing China

During formation of the Tarim Basin, there repetitively happened seawater invasion for it was ever connected with wide Paleo-mediterranean Sea. At the same time, for the applica-tion of tectonic and paleoenvironmental condition, the basin deposits many sequences of thick strata of evaporites, especially in its two largest subbasins of Kuqa in the north and Shaqa in the southwest. Therefore, the western Tarim Basin has been considered to be a favorable location to prospect ancient sylvinite deposit. But it is unfortunate that the Br×1.3/Cl ratio, as a common geochemical index to uncover clues of sylvinite deposit, is almost invalid to indicate the stage of ancient brine condensation for very low content of bromine in salt rock samples (less than 1.?6 commonly) in the western Tarim Basin evaporites. Fortunately, we noticed recently that the val-ues of chlorine isotope (δ 37Cl value) for salt rock samples follow some clear laws from place to place, which in the Shaqa subbasin, all δ 37Cl values of salt rock samples behaved negatively and on the contrary, they all surprisingly showed positive values in the Kuqa subbasin. Based on conclusions of previous research and referring to the ratios of Br×1.3/Cl for salt rock or brine samples, we proved that the chlorine isotope (δ 37Cl) could be used as an effective index to find ancient sylvinite deposit in those evaporites rock basin with low content of Br element back-ground, such as the Tarim Basin. Thus according to the new index of chlorine isotope, we con-clude that the concentration of ancient brines formed ancient salt rocks is much more concen-trated in the Shaqa subbasin than that in the Kuqa subbasin. Particularly, the δ 37Cl value of salt rock in Kashi depression of the western Shaqa subbasin is greatly negative (1.00‰), which may predicate that the ancient brine has been concentrated to the terminal stage of salt deposit or even the later stage of sylvinite deposit. Then it is possible to find sylvinite-bearing d

关键词： the Tarim Basin, chlorine isotope, ancient salt rock, ancient sylvinite deposit, deposit stage

Artificial coordinating field and its application to motion planning of robots in uncertain dynamic environments

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Science China(Technological sciences) 2004年第5期47卷 577-594页

作者： JING Xingjian1. 2. WANG Yuechao1.& TAN Dalong1.1. Robotics Laboratory, Shenyang {1. of Automation,{1., Shenyang 1.001., China 2. Graduate School,{1., Beijing 1.0039, China Correspondence should be addressed to Jing Xingjian 1. Robotics Laboratory Shenyang Institute of Automation Chinese Academy of Sciences 10016 Shenyang China 2. Graduate School Chinese Academy of Sciences 10039 Beijing China

Artificial coordinating fields (ACF) are proposed to deal with the motion planning problems of mobile robots in uncertain dynamic environments. An ACF around an obstacle can generate two orthogonal force vectors to a robot: one is called the coordinating force vector which is purposively designed in this paper, and the other is the repulsive force vector which is the same as that in a conventional artificial potential field. The ACF is designed according to the updated motion purpose and the relative states of the robot with respect to its local environment, and it also satisfies the robot’s dynamic constraints. The direction of the coordinating force can be determiend on line according to an optimal evaluation function. The ACF can effectively remove the local minima, and reduce the oscillation of the planned trajectory between multiple obstacles. Only local knowledge of the environments is needed in the ACF-based motion planning. The properties of the ACF such as controllability, adaptability, safety and reachability are studied and discussed in detail in this paper. Theoretical analysis and simulations are given to illustrate our main results.

关键词： artificial coordinating fields, artificial potential fields, mobile robots, motion planning, uncertain dynamic environments.

New technique to control in situ oxygen fugacity in water-free high-pressure system──Using Cu-O as an example

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chinese Science Bulletin 1998年第16期43卷 1353-1358页

作者： LI Heping 1. XIE Hongsen 1. GUO Jie 1. ZHANG Yueming 1.XU Zuming 1.and XU Ji’an 2.1. {1. of Geochemistry,{1., Guiyang 550002. China 2. {1. of Earth sciences, Taiwan 1.52., China institute of Geochemistry Chinese Academy of Sciences Guiyang China institute of Earth {1. Taiwan China

Through inserting a solid oxygen-specific electrolyte (YSZ) inside and exerting an electrical power of direct current outside between the sample and oxygen reservoir (an solid oxygen buffer), oxygen was driven by the power from the cathodic electrode area into the positive electrode area at high temperature and high pressure. In this way, the oxygen fugacity in the sample was in situ controlled independently of temperature and pressure. By using Cu-O system as an example, this technique was proved to be successful.

关键词： in situ control of oxygen fugacity water-free system high temperature and high pressure.