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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),{2., Chinese Academy of Sciences, beijing 10002., China 2.Graduate University of Chinese Academy of Sciences, {4. 10004., China paleomagnetism and geochronology {2. (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

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. {2. and {4. laboratory (SKL of Lithosphere Evolution),{4., Chi- nese Academy of Sciences, beijing 10002., 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 554.5, USA paleomagnetism and geochronology {2. (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～4. 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 4..7-4..7 ka, which is close to the widely accepted age of ～4.-4. 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.

SHRIMP zircon U-Pb geochronology of early Mesozoic felsic igneous rocks from the southern Lancangjiang and its tectonic implications

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Science China Earth Sciences 2006年第10期49卷 1032-1042页

作者： PENG Touping1,2. WANG Yuejun1, FAN Weiming1, liu Dunyi3, SHI Yuruo3 & MIAO Laicheng4.1. Key laboratory of Isotope {2. and Geochemistry, Guangzhou {4. of Geochemistry, Chinese Academy of Sciences, Guangzhou 51064., China 2. Graduate University of Chinese Academy of Sciences, beijing 100039, China 3. SHRIMP isotope laboratory, Chinese Academy of Geological Sciences, beijing 100037, China 4. institute of geology and geophysics, Chinese Academy of Sciences, beijing 10002., China Key laboratory of Isotope geochronology and Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China Graduate University of Chinese Academy of Sciences Beijing China SHRIMP isotope laboratory Chinese Academy of Geological Sciences Beijing China institute of geology and {2. Chinese Academy of Sciences Beijing China

The SHRIMP zircon U-Pb geochronology of three typical samples, including two monzo nitic granites from the Lincang batholith and a rhyolite from the Manghuai Formation are presented in the southern Lancangjiang, western Yunnan Province. The analyses of zircons for the biotite monzonitic granites from the northern (02.X-137) and southern (2.JH-10) Lincang batholith show the single and tight clusters on the concordia, and yield the weighted mean 2.6Pb/2.8U ages of 2.9.4.± 3.0 Ma and 2.0.4.± 3.6 Ma, respectively, representing the crystallized ages of these granites. The zircons for the rhyolitic sample (02.X-95) from the Manghuai Formation give a weighted mean 2.6Pb/2.8U age of 2.1.0 ± 5.0 Ma. These data suggest that the igneous rocks from the Lincang granitic batholith and Manghuai Formation have a similar crystallized age. In combination with other data, it is inferred that both were generated at a narrow age span (~2.0 Ma) and were originated from the postcollisional tectonic regime. An early Proterozoic 2.6Pb/2.8U apparent age of 1977±4. Ma is additionally obtained from one zircon from the biotite monzonitic granite (southern Lincang batholith), indicative of devel- opment of the early Proterozoic Yangtze basement in the region. These precisely geochronological data provide important constraints on better understanding the Paleozoic tectonic evolution of the Tethys, western Yunnan Province.

关键词： SHRIMP zircon U-Pb dating, Middle Triassic, Lincang granitic batholith, Manghuai Formation rhyolite, southern Lancangjiang.

Method to measure tree-ring width,density,elemental composition,and stable carbon and oxygen isotopes using one sample

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Journal of Forestry Research 2024年第3期35卷 167-174页

作者： Chenxi Xu Yaru zhao Wenling An Qingyu zhao Yucheng {2. Masaki Sano Takeshi Nakatsuka Key laboratory of Cenozoic geology and Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029People's Republic of China CAS Center for Excellence in Life and Paleoenvironment Beijing 100044People's Republic of China College of Earth Sciences University of Chinese Academy of SciencesBeijing 100049People's Republic of China Graduate School of Environment Studies Nagoya UniversityNagoya 4648601Japan

Tree-ring width(RW),density,elemental com-position,and stable carbon and oxygen isotope(δ^(13)C,δ^(18)O)are widely used as proxies to assess climate change,ecology,and environmental pollution;however,a specific pretreat-ment has been needed for each ***,we developed a method by which each proxy can be measured in the same ***,the sample is polished for ring width *** obtaining the ring width data,the sample is cut to form a 1-mm-thick wood *** sample is then mounted in a vertical sample holder,and gradually scanned by an X-ray ***,the count rates of the fluorescent photons of elements(for chemical characteriza-tion)and a radiographic grayscale image(for wood density)are obtained,*** density and the element content are ***,cellulose is isolated from the 1-mm wood plate by removal of lignin,and *** producing this cellulose plate,cellulose subsamples are separated by knife under the microscope for inter-annual and intra-annual stable carbon and oxygen isotope(δ^(13)C,δ^(18)O)*** on this method,RW,density,elemental composition,δ^(13)C,and δ^(18)O can be measured from the same sample,which reduces sample amount and treatment time,and is helpful for multi-proxy comparison and combination research.

关键词： Tree-ring width Tree-ring density Tree-ring elemental composition Tree-ring stable carbon and oxygenisotopes

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

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Effects of the grain size distribution on the temperature-de...

中国科学院地质与地球物理研究所第十届(2.10年度)学术年会

作者： zhao xiangyu~(1,2. & {2. {4.~(1*) 1 paleomagnetism and {4. laboratory(SKL-LE),institute of geology and geophysics,Chinese Academy of Sciences, beijing 10002.,China 2.Graduate University of Chinese Academy of Sciences,beijing 10004.,China

Magnetite is an important magnetic remanence carrier in natural samples and therefore is of great interest in paleo-,rock-,and environmental *** 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 *** show that the TDS is affected highly by the GSD mainly in three ***, the unblocking process becomes smoother with the increase of distribution width,characterizing as a wider Hopkinson peak on the TDS ***,the blocking temperature increases with the increase of the median diameter or/and the distribution ***,the maximum susceptibility decreases with the increase of distribution width,and has a logarithmic function relation with the standard deviation of the *** 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 *** results demonstrate the fidelity and feasibility of this method to determine the GSD of nano-sized magnetic particles.

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

Zircon Hf Isotope Mapping for Understanding Crustal Architecture and Its Controls on Mineralization during Early Cretaceous in the Southern Great Xing'an Range,NE China

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Journal of Earth Science 2024年第1期35卷 41-50页

作者： Feng Yuan Huanan liu Shengjin zhao Mingjing Fan State Key laboratory of Geological Processes and Mineral Resources Collaborative Innovation Center for Exploration of Strategic Mineral ResourcesSchool of Earth ResourcesChina University of GeosciencesWuhan 430074China State Key laboratory of Geological Processes and Mineral Resources School of Earth Sciences and ResourcesChina University of GeosciencesBeijing100083China No.10 institute of Geological Exploration Inner Mongolia Bureau of Geology and Mineral ResourcesChifeng 024000China Key laboratory of Metallogeny and Mineral Assessment Institute of Mineral ResourcesChinese Academy of Geological SciencesBeijing 100037China

Voluminous Early Cretaceous granitoids and associated large-scale ore deposits are distributed within the southern Great Xing'an Range(SGXR),NE *** on previously published geochronology and zircon Hf-isotope data,Hf isotope mapping is undertaken to improve our understanding of crustal architecture and its controls on ore *** ore-related Early Cretaceous granitoids were sourced predominantly from juvenile crust,with the involvement of variable proportions of ancient crustal *** crustal architecture,as inferred from Hf isotopic contour maps,indicates two distinct Hf isotopic domains in SGXR,including(1)a higher-ε_(Hf)(+7 to+11)juvenile crust containing minor ancient crustal material,and(2.a lower-ε_(Hf)(+2.to+6)juvenile crust containing a greater proportion of ancient crustal *** Hf isotopic maps identify links between crustal architecture and regional *** deposits and other deposits with significant Cu production are restricted mainly to the higher-ε_(Hf)juvenile crustal regions in the northern and eastern *** dominated by other metals(e.g.,Mo,Sn,W,Pb,Zn,and Ag)occur mainly in the lower-ε_(Hf)juvenile crustal regions in the southern and western *** between juvenile crust-derived melts and ancient crustal components played an important role on the distribution of various ore metals.

关键词： Hf isotope mapping crustal architecture large-scale Early Cretaceous granitoids distribution of ore deposits southern Great Xing'an Range zircon

Reliability of the natural remanent magnetization recorded in Chinese loess

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Reliability of the natural remanent magnetization recorded i...

中国科学院地质与地球物理研究所第十届(2.10年度)学术年会

作者： Chunsheng Jin and qingsong liu 1 {2. and {2. {4.,{4. of geology and geophysics,Chinese Academy of Sciences,beijing,China.

[1]Chinese loess-paleosol sequences undoubtedly have recorded geomagnetic events (both polarity reversals and excursions).However,the fidelity of the rapid paleomagnetic field oscillations during a polarity reversal remains *** test the reliability and consistency of the natural remanent magnetization records in Chinese loess,10 subsets of parallel samples across the Matuyama-Brunhes(MB)reversal boundary were obtained from the Luochuan region in the hinterland of the Chinese Loess *** paleomagnetic results show diversified virtual geomagnetic poles(VGPs)during the MB transition but consistent VGPs outside of the transitional *** anisotropy of magnetic susceptibility and rock magnetism results indicate that the sampled interval is rather uniform and *** discrepancies of the characteristic remanent magnetization within the MB transition are probably due to the low efficiency in aligning magnetic grains,mainly pseudo-single-domain magnetite,associated with the low field intensity. Nevertheless,the stratigraphic location of the MB boundary can be confidently defined. Therefore,we conclude that Chinese loess-paleosol sequences can record geomagnetic reversal events,but the morphology within the polarity transition is rather questionable.

关键词：

Thermally induced inversion of Al-substituted titanomagnetite in basalts:Evidence for partial self-reversal

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Thermally induced inversion of Al-substituted titanomagnetit...

中国科学院地质与地球物理研究所2.06学术年会

作者： Yongxin Pan~1,qingsong liu~2.Chenglong Deng~1,Huafeng Qin~1,and Rixiang Zhu~1 (1 {2. and {4. laboratory,{4. of geology and geophysics,Chinese Academy of Sciences,beijing,China.2.National Oceanography Centre,University of Southampton,Southampton,UK.)

We report properties of laboratory-induced thermoremanence combined with detailed rock magnetic experiments on basaltic samples which contain aluminum-substituted titanomagnetite(Fe2.2.Ti0.64.10.12.4..Prior to Thellier-Coe paleointensity experiments, specimens were first demagnetized using an alternating field with a peak field of 90 Mt and were then imparted an anhysteretic remanent magnetization(ARM) to represent a natural remanent magnetization(NRM).Results show that the partial thermal remanent magnetization(pTRM) gain and ARM remaining are linearly correlated up to *** 300 and 4.0,specimens acquire thermoremanence with a direction antiparallel to the external field direction,leading to intensity *** coincides with the onset of the mineral transformation from Al-titanomagnetite to a magnetic phase with higher *** results support that phase interaction with distinct Tc values in partially oxidized titanomagnetite can produce partial self-reversal thermoremanence in rocks

关键词： titanomagnetite partial self-reversal

Identifying the origin of the magnetic directional anomalies recorded in the Datong loess profile,northeastern Chinese loess plateau

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Identifying the origin of the magnetic directional anomalies...

中国科学院地质与地球物理研究所2.06学术年会

作者： Rixiang Zhu,~1 qingsong liu,~(1,2. Yongxin Pan,~1 Chenglong Deng,~1 Jimin Sun~1 1 Palaeomagnetism and {2. {4.(SKL-LE),institute of {4. and geophysics,Chinese Academy of Sciences,beijing 10002.,China 2.Department of Earth Sciences,University of California at Santa Cruz,CA 95064.USA

To better understand the origin of short-term features of palaeomagnetic signals recorded by the Chinese loess,detailed palaeomagnetic and magnetic fabric studies were conducted on a loess profile at Datong,the northeastern margin of the loess plateau,which is characterized by both high sedimentation rate(□18 cm ka-1) and variations of sedimentary *** appears that the magnetic fabrics,specifically the inclination of the maximum magnetic susceptibility principal axis(K1-Inc),are robust means to identify the deposition *** results(4.ka) record four palaeodirectional anomalies(referred as A-D). Among them,anomaly C with relatively normal fabrics can be correlated to the Laschamp(□4. ka) *** contrast,anomalies A,B and D accompanying with Kl-Inc anomalies,are interpreted to be caused by post-depositional *** new results improve our understanding of the origins of the natural remanent magnetization recorded by the Chinese loess.

关键词： Chinese loess geomagnetic excursions magnetic fabrics

Time delay and duration of ionospheric total electron content responses to geomagnetic disturbances

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中国科学院地质与地球物理研究所第十届(2.10年度)学术年会

作者： J.liu~(1,2.,B.zhao~1,and L.liu~1 1{4.,Chinese Academy of Sciences,{2. 10002.,China 2.Graduate University of Chinese Academy of Sciences,{2.,China

Although positive and negative signatures of ionospheric storms have been reported many times,global characteristics such as the time of occurrence,time delay and duration as well as their relations to the intensity of the ionospheric storms have not received enough *** 10 years of global ionosphere maps(GIMs) of total electron content(TEC) retrieved at Jet Propulsion laboratory(JPL) were used to conduct a statistical study of the time delay of the ionospheric responses to geomagnetic *** results show that the time delays between geomagnetic disturbances and TEC responses depend on season,magnetic local time and magnetic *** the summer hemisphere at mid- and high latitudes,the negative storm effects can propagate to the low latitudes at post-midnight to the morning sector with a time delay of 4.7 *** the earth rotates to the sunlight,negative phase retreats to higher latitudes and starts to extend to the lower latitude toward midnight *** the winter hemisphere during the daytime and after sunset at mid- and low latitudes,the negative phase appearance time is delayed from 1-10 h depending on the local time,latitude and storm intensity compared to the same area in the summer *** quick response of positive phase can be observed at the auroral area in the night-side of the winter hemisphere. At the low latitudes during the dawn-noon sector,the ionospheric negative phase responses quickly with time delays of 5-7 h in both equinoctial and solsticial months. Our results also manifest that there is a positive correlation between the intensity of geomagnetic disturbances and the time duration of both the positive phase and negative phase. The durations of both negative phase and positive phase have clear latitudinal,seasonal and magnetic local time(MLT) dependence. In the winter hemisphere,long durations for the positive phase are 8-11 h and 12.14.h during the daytime at middle and high latitudes for 2.≤Ap4. and Ap≥4..

关键词： Ionosphere(Equatorial ionosphere Ionosphere magnetosphere interactions Ionospheric disturbances)