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Destruction geodynamics of the North China Craton and its Paleoproterozoic plate tectonics

Chinese Science Bulletin 2009年第19期54卷 3354-3366页

作者： ZHU RiXiang ZHENG TianYu paleomagnetism and geochronology laboratory (SKL-LE) Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China

Much attention has been paid in the last two decades to the physical and chemical processes as well as temporal-spatial variations of the lithospheric mantle beneath the North China Craton. In order to provide insights into the geodynamics of this variation, it is necessary to thoroughly study the state and structure of the lithospheric crust and mantle of the North China Craton and its adjacent regions as an integrated unit. Based on the velocity structure of the crust and upper mantle constrained from seismological studies, this paper presents various available geophysical results regarding the lithosphere thickness, the nature of crust-mantle boundary, the upper mantle structure and deformation characteristics as well as their tectonic features and evolution systematics. Combined with the obtained data from petrology and geochemistry, a mantle flow model is proposed for the tectonic evolution of the North China Craton during the Mesozoic-Cenozoic. We suggest that subduction of the Pacific plate made the mantle underneath the eastern Asian continent unstable and able to flow faster. Such a regional mantle flow system would cause an elevation of melt/fluid content in the upper mantle of the North China Craton and the lithospheric softening, which, subsequently resulted in destruction of the North China Craton in different ways of delamination and thermal erosion in Yanshan, Taihang Mountains and the Tan-Lu Fault zone. Multiple lines of evidence recorded in the crust of the North China Craton, such as the amalgamation of the Archean eastern and western blocks, the subduction of Paleo-oceanic crust and Paleo-continental residue, indicate that the Earth in the Paleoproterozoic had already evolved into the plate tectonic system similar to the present plate tectonics.

关键词：地球动力学筑造学研究调查

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Magnetic properties of high-road-side pine tree leaves in Beijing and their environ-mental significance

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Chinese Science Bulletin 2006年第24期51卷 3041-3052页

作者： ZHANG Chunxia HUANG Baochun LI Zhenyu LIU He paleomagnetism and geochronology laboratory (SKL-LE) Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China

This is a report on magnetic properties of highroad-side tree (Pinus pumila Regel) leaves collected along an expressway linking Beijing City and the Capital International Airport and further focus on their environmental contributions. A series of rock magnetic experiments show that the primary mag-netic mineral of leaf samples was identified to be magnetite,in the pseudo-single domain (PSD) grain size range 0.2―5.0 μm. On the other hand,magnet-ite concentration and grain size in leaves are ascer-tained to decrease with increasing of sampling dis-tance to highroad asphalt surface,suggesting that high magnetic response to traffic pollution is localized within a distance of some two meters away from highroad asphalt surface. Although magnetic suscep-tibility is ordinarily regarded as a simple,rapid and low-cost method for monitoring traffic pollution,saturation isothermal remanent magnetization (SIRM) can be treated as a valid proxy for monitoring air par-ticulate matter (PM) when samples are magnetically weak. It is believed that a synthetic rock magnetic study is an effective method for determining concen-tration and grain size of ferromagnets in the atmos-pheric PM,and then it should be a rapid and feasible technique for monitoring atmospheric pollution.

关键词：公路行道树路侧树木松树树叶交通污染空气污染磁学性质

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Effects of the grain size distribution on the temperature-dependent magnetic susceptibility of magnetite nanoparticles

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Science China Earth Sciences 2010年第7期53卷 1071-1078页

作者： ZHAO XiangYu1,2 & LIU QingSong1 1 paleomagnetism and geochronology laboratory (SKL-LE), Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China 2 Graduate University of Chinese Academy of Sciences, Beijing 100049, China paleomagnetism and geochronology laboratory (SKL-LE) Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China Graduate University of Chinese Academy of Sciences Beijing China

Magnetite is an important magnetic remanence carrier in natural samples and therefore is of great interest in paleo-, rock-, and environmental magnetism. The magnetic properties of magnetite depend on many factors, e.g., concentration and grain size distribution (GSD). In this study, we theoretically investigated the temperature-dependent susceptibility (TDS) of magnetite nanoparticles with a lognormal GSD. Results show that the TDS is affected highly by the GSD mainly in three aspects. Firstly, the unblocking process becomes smoother with the increase of distribution width, characterizing as a wider Hopkinson peak on the TDS curve. Secondly, the blocking temperature increases with the increase of the median diameter or/and the distribution width. Thirdly, the maximum susceptibility decreases with the increase of distribution width, and has a logarithmic function relation with the standard deviation of the distribution. As a case study, this model was further applied to the thermal products of the Chinese loess/paleosol samples to determine the granulometry of newly-formed magnetite upon heating based on TDS curves. The results demonstrate the fidelity and feasibility of this method to determine the GSD of nano-sized magnetic particles.

关键词： Néel theory temperature dependence of susceptibility grain size distribution

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Recover vigorous cells of Magnetospirillum magneticum AMB-1 by capillary magnetic separation

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Chinese Journal of Oceanology and Limnology 2010年第4期28卷 826-831页

作者：李金华葛欣张小葵陈冠军潘永信 State Key laboratory of Microbial Technology Shandong University Biogeomagnetism Group Paleomagnetism and Geochronology Laboratory(SKL-LE)Institute of Geology and GeophysicsChinese Academy of Sciences Marine College Shandong University at Weihai

Cultivable magnetotactic bacteria(MTB) in laboratory can provide sufficient samples for molecular microbiological and magnetic ***,a cold-stored MTB strain,such as Magnetospirillum magneticum AMB-1,often loses its ability to synthesize magnetosomes and consequently fails to sense the external magnetic *** is therefore important to quickly recover vigorous bacteria cells that highly capable of magnetosome *** this study,a modified capillary magnetic separation system was designed to recover a deteriorating strain of Magnetospirillum magneticum AMB-1 that long-term cold-stored in a *** results show that all cells obtained after a 3-cycle treatment were vigorous and had the ability to produce ***,the 3rd-cycle recovered cells were able to form more magnetosome *** with the colony formation method,this new method is time-saving,easily operated,and more efficient for recovering vigorous MTB cells.

关键词： magnetotactic bacteria Magnetospirillum magneticum AMB-1 capillary magnetic separation strain recovery

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Identification of the thick-layer greigite in sediments of the South Yellow Sea and its geological significances

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Chinese Science Bulletin 2014年第22期59卷 2764-2775页

作者： Jianxing Liu Xuefa Shi Shulan Ge Qingsong Liu Zhengquan Yao Gang Yang paleomagnetism and geochronology laboratory (SKL-LE) Institute of Geology and Geophysics Chinese Academy of Sciences University of Chinese Academy of Sciences Key laboratory of Marine Sedimentation and Environmental Geology First Institute of Oceanography State Oceanic Administration

Magnetic minerals in sediments of the continental shelf are sensitive to environmental ***,to determine the exact phases of magnetic minerals is the prerequisite to investigate the paleoenvironmental *** this study,a comprehensive rock magnetic investigation,coupled with mineralogical studies,was carried out on the long core NHH01(with a length of 125.64 m)from the central continental shelf of the South Yellow ***-domain greigite was identified as the dominant magnetic carrier in sediments between44.90 and 51.80 m,and terrigenous magnetite is the major magnetic phase in the adjacent *** existence of greigite unambiguously indicates an anoxic *** tentatively interpreted that such an environment could be formed by the fast sea level changes,long-existing of the cold eddies during warm stages,or in a lake which might be related to locally tectonic ***,the occurrence of the thick-layer greigite could supply a new perspective to paleoenvironmental or even tectonic studies.

关键词：南黄海中部沉积物地质意义古环境意义识别厚层环境变化磁性矿物

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Paleomagnetic dating of the Cenjiawan Paleolithic site in the Nihewan Basin, northern China

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Science China Earth Sciences 2006年第3期49卷 295-303页

作者： WANG Hongqiang1,2, DENG Chenglong1, ZHU Rixiang1 & XIE Fei3 1. paleomagnetism and geochronology laboratory (SKL-LE), Institute of Geology and Geophysics, Chinese Academy of Sci- ences, Beijing 100029, China 2. School of the Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China 3. Hebei Province Institute of Cultural Relics, Shijiazhuang 050000, China paleomagnetism and geochronology laboratory (SKL-LE) Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China School of the Earth Sciences and Resources China University of Geosciences Beijing China Hebei Province Institute of Cultural Relics Shijiazhuang China

Rock magnetic and magnetostratigraphic investigations on a lacustrine sequence in the Nihewan Basin, northern China, which bears the Cenjiawan Paleolithic site, indicate that the dominant magnetic mineral and remanence carrier contained in the sediments is magnetite. While hematite co-exists with magnetite in some portions of the Cenjiawan sequence, where characteristic remanent magnetizations are carried by both magnetite and hematite. Measurements of anisotropy of magnetic susceptibility confirm that the Cenjiawan sequence has preserved the original sedimentary features and is suitable for magnetostratigraphic study. Paleomagnetic results indicate that the Cenjiawan Paleolithic site is formed just posterior to the Punaruu normal event, which is dated at about 1.1 Ma. Combined with the paleomagnetic results of the Donggutuo, Xiaochangliang and Majuangou sections, it is concluded that early humans were occupying the Nihewan Basin around 1.6, 1.3 and 1.1 Ma. This integrated result is significant to understanding the ability of migration and adaptation to the envi- ronment of early humans.

关键词： Nihewan Basin, Early Pleistocene, Cenjiawan, Paleolithic site, paleomagnetism.

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Petromagnetic Properties of Granulite-Facies Rocks from the Northern North China Craton: Implications for Magnetic and Evolution of the Continental Lower Crust

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Journal of Earth Science 2013年第1期24卷 12-28页

作者：刘庆生王红才郑建平曾庆理刘青松 Institute of Geophysics & Geomatics China University of Geosciences Institute of Geomechanics Chinese Academy of Geological Sciences Faculty of Earth Sciences China University of Geosciences paleomagnetism and geochronology laboratory (SKL-LE) Institute of Geology and Geophysics Chinese Academy of Sciences

This paper studies magnetic properties and composition of granulite-facies rocks of both the Neogene and Archean continental lower crust in the Neogene xenolith-bearing Hannuoba （汉诺坝） alkaline basalt and the exposed lower crustal section in the Archean Huai＇an （淮安） terrain （Wayaokou （瓦窑口）-Manjinggou （蔓菁沟） profile）, the northern North China Craton. It provides a unique oppor-tunity for a comparative study of magnetic properties and composition of both the Archean and Neogene continental lower crust. We measure magnetic parameters （susceptibility x and magnetic hysteresis parameters, such as saturation magnetization Js, saturation isothermal remanent magnetization Jrs, and intrinsic coercivity He） of eleven Hannuoba lower crustal xenoliths and nine terrain granulites from the Archean Huai＇an terrain. Results indicate that the average values of K,Js and Jrs of Archean granu- lites are 4 122×10^-6 SI, 523.1 A/m and 74.9 A/m, respectively, which are generally higher than those of granulite-facies xenoliths （1 657×10^-6 SI, 163.9 A/m and 41.9 A/m, respectively）. These two types of granulites contain ilmenite, （titano） magnetite, minor hematite and some ＂magnetic silicates＂（clinopyroxene, plagioclase and biotite）. The Mg-rich ilmenite in granulite-facies xenolith is relatively higher than that in terrain granulites. We observe a more evolved character as higher magnetic as well as lower Sr/Nd, Cr/Nd, Ni/Nd, Co/Nd and V/Nd ratios in terrain granulites. These differences in magnetic characteristics reflect their different origins and evolutions. The high magnetization of granulites in the Huai＇an terrain represents magnetic properties of the Archean continental lower crust, and low magnetization of granufite-facies xenoliths represents mag- netic properties of the Cenozoic lower crusts in the northern North China Craton.

关键词： rock and mineral magnetism magnetic mineralogy and petrology metamorphic pe-trology North China Craton

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No apparent lock-in depth of the Laschamp geomagnetic excursion: Evidence from the Malan loess

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Science China Earth Sciences 2006年第9期49卷 960-967页

作者： ZHU Rixiang1, LIU Qingsong1,2, PAN Yongxin1, DENG Chenglong1, ZHANG Rui1 & WANG Xianfeng3 1. paleomagnetism and geochronology laboratory (SKL of Lithosphere Evolution), Institute of Geology and Geophysics, Chi- nese Academy of Sciences, Beijing 100029, China 2. Institute of Geophysics and Planetary Geophysics, University of California, Santa Cruz, CA 95064, USA 3. Department of Geology and Geophysics, University of Minnesota, Minneapolis, MN 55455, USA paleomagnetism and geochronology laboratory (SKL of Lithosphere Evolution) Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China Institute of Geophysics and Planetary Geophysics University of California Santa Cruz USA Department of Geology and Geophysics University of Minnesota Minneapolis USA

The first-order chronological framework of the long-term Chinese loess/paleosol sequences was based mainly on magnetostratigraphy. However, there remain arguments on the lock-in ages of the major geomagnetic reversals. This study systematically compared the stratigraphic locations of the Laschamp excursion and Henrich events (H4 at～39 ka and H5 at～48 ka) recorded by the Luochuan loess profile in the central Chinese Loess Plateau. Results show that the Lascchamp excursion is bracketed well by these two cold events, and the corresponding estimated age is between about 41.7-43.7 ka, which is close to the widely accepted age of ～40-41 ka for the ***, our new results do not suggest apparent lock-in effects in the last glacial Malan loess.

关键词： Chinese loess, Laschamp excursion, Henrich event, lock-in depth.

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DMTB:A comprehensive online resource of 16S rRNA genes,ecological metadata,oligonucleotides,and magnetic properties of magnetotactic bacteria

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Chinese Science Bulletin 2011年第6期56卷 476-478页

作者： LIN Wei1,2, LI Bi1,2 & PAN YongXin1,2 1 paleomagnetism and geochronology laboratory, Key laboratory of the Earth’s Deep Interior, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China 2 France-China Bio-Mineralization and Nano-Structures laboratory, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China paleomagnetism and geochronology laboratory Key Laboratory of the Earth’s Deep Interior Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China France-China Bio-Mineralization and Nano-Structures laboratory Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China

Magnetotactic bacteria (MTB) are of interest in microbiology, biomineralization, advanced magnetic materials, and bio-geo-sciences because of their ability to form highly ordered intracellular magnetic minerals. Great strides for MTB studies have been made in the past four decades. In this paper we complied the first internet-accessible database for MTB, Database of Magnestotactic Bacteria (DMTB). It contains information of 16S rRNA gene sequences, corresponding ecological metadata, oligonucleotides, and magnetic properties of MTB. The comprehensive information contained in DMTB will provide a very useful data resource for researchers from different disciplines. The website of DMTB is at http://***/.

关键词： rRNA基因序列趋磁细菌 16S 网上资源寡核苷酸磁学性质生态磁性材料

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In vitro assembly of the bacterial actin protein MamK from ＇Candidatus Magnetobacterium casensis＇ in the phylum Nitrospirae

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Protein & Cell 2016年第4期7卷 267-280页

作者： Aihua Deng Wei Lin Nana Shi Jie Wu Zhaopeng Sun Qinyun Sun Hua Bai Yongxin Pan Tingyi Wen CAS Key laboratory of Pathogenic Microbiology and Immunology Institute of Microbiology Chinese Academy of Sciences Beijing 100101 China Biogeomagnetism Group Paleomagnetism and Geochronology Laboratory Key Laboratory of Earth and Planetary Physics Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China University of Chinese Academy of Sciences Beijing 100049 China

Magnetotactic bacteria （MTB）, a group of phylogeneti- cally diverse organisms that use their unique intracellular magnetosome organelles to swim along the Earth＇s magnetic field, play important roles in the biogeochemical cycles of iron and sulfur. Previous studies have revealed that the bacterial actin protein MamK plays essential roles in the linear arrangement of magnetosomes in MTB cells belonging to the Proteobacteria phylum. However, the molecular mechanisms of multi- ple-magnetosome-chain arrangements in MTB remain largely unknown. Here, we report that the MamK filaments from the uncultivated ＇Candidatus Magnetobacterium casensis＇（Mcas） within the phylum Nitrospirae polymerized in the presence of ATP alone and were stable without obvious ATP hydrolysis-mediated disassembly. MamK in Mcas can convert NTP to NDP and NDP to NMP, showing the highest preference to ATP. Unlike its Magnetospirillum counterparts, which form a single magnetosome chain, or other bacterial actins such as MreB and ParM, the polymerized MamK from Mcas is independent of metal ions and nucleotides except for ATP, and is assembled into well-ordered filamentous bundles consisted of multiple filaments. Our results suggest a dynamically stable assembly of MamK from the uncultivated Nitrospirae MTB that synthesizes multiple magnetosome chains per cell, These findings further improve the current knowledge of biomineralization and organelle biogenesis in prokaryotic systems.

关键词： magnetotactic bacteria Nitrospirae,bacterial actin MamK assembly mechanism

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