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Relative paleointensity of the geomagnetic field during the past 200 ka from the West Philippine Sea and its chronological significance

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Science China Earth Sciences 2009年第8期52卷 1115-1126页

作者： QingYong Meng AnChun Li TieGang Li FuQing Jiang XiaoJing Zhou Key Lab of Marine Geology & Environment Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China Graduate University of the Chinese Academy of Sciences Beijing 100049 China

Our rock magnetic analysis of core Ph05 from the West Philippine Sea demonstrates that the core preserves a strong, stable remanent magnetization and meets the magnetic mineral criteria for relative paleointensity (RP... 详细信息

关键词： West Philippine Sea relative paleointensity geomagnetic field

Towards the robust selection of Thellier-type paleointensity data:The influence of experimental noise

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Towards the robust selection of Thellier-type paleointensity...

Thellier-type paleointensity data from multidomain specimens

中国科学院地质与地球物理研究所2012年度（第12届）学术年会

作者： Greig A.Paterson Andrew J.Biggin Yuhji Yamamoto Yongxin Pan Paleomagnetism and Geochronology Laboratory Key Laboratory of Earth's Deep InteriorInstitute of Geology and GeophysicsChinese Academy of Sciences Geomagnetism Laboratory Geology and GeophysicsSchool of Environmental SciencesUniversity of Liverpool Center for Advanced Marine Core Research Kochi University

[1]The process of data selection in paleointensity studies is an essential step to ensure data *** is, however,no consensus as to the best approach to consistently select data with most studies using arbitrarily defined thresholds for *** present a new numerical model that simulates the variability of paleointensity data from hypothetical ideal samples acquiring a thermoremanent magnetization(TRM) by incorporating experimental noise,which has been constrained using over 75,000 data *** Monte Carlo analyses,we investigate the behavior of simulated data and characterize the distributions of parameters typically used to select paleointensity *** use the 95th percentiles of the distributions to define thresholds for the maximum likely parameter values that can result from experimental *** represent values below which we cannot distinguish non-ideal behavior from *** find that a number of parameters are highly sensitive to noise and laboratory field strength(e.g.,partial TRM,pTRM,check CDRAT and pTRM tail checkδt);this sensitivity may diminish their ability to identify non-ideal *** fractional(f) dependence of some parameters and the proportion of inaccurate results provide justification for f≥0.35 when selecting data from both Thellier-Thellier and Coe protocol *** manifestation of noise in the original Thellier method,however,is different to that of methods that use zero-field heating *** suggests that the data selection procedure for the Thellier method should be different,but it also suggests that, contrary to previous analyses,the accuracy and scatter of results from this method are more sensitive to noise than methods that use zero-field heating *** general approach taken here is shown to be a powerful means of understanding the behavior of selection parameters and has the potential to be extended to models incorporating non-ideal behavior resulting from alteration and multidomain

关键词： error analysis experimental noise non-ideal behavior paleointensity

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Thellier-type paleointensity data from multidomain specimens

Is there a precursor to the Cretaceous normal superchron? New paleointensity and age determination from Liaoning province,northeastern China

中国科学院地质与地球物理研究所2015年度（第15届）学术年会

作者： Greig A.Paterson Andrew J.Biggin Emma Hodgson Mimi J.Hill Key Laboratory of Earth and Planetary Physics Institute of Geology and Geophysics Chinese Academy of Sciences

Identifying and excluding inaccurate paleointensity estimates that can arise from the effects of multidomain(MD) particles remains a key challenge for paleointensity studies. Here we approach this problem by incorporating realistic experimental noise into a phenomenological MD model, systematically exploring the parameter space of paleointensity experiments(the choice of protocol, laboratory field strengths and directions), applying optimization algorithms to the model predictions, and testing these against experimental datasets. The results allow us to conclude that:(1) In some cases, applying the lab field in a direction [60 from the NRM direction and with a magnitude～2 times larger than the ancient field may help to produce more linear and accurate Arai plots by allowing partial thermoremanent magnetization(p TRM) tails to compensate from excess natural remanent magnetization(NRM) loss, the mechanism behind typical MD Arai plot curvature.(2) The recently proposed FRAC criterion is consistently better at isolating accurate results than the traditionally used f parameter and should ideally have minimum values of 0.65, 0.45, 0.65, and 0.55 for the Thellier, Coe, Aitken, and IZZI protocols, respectively.(3) Newly developed sets of selection criteria(MC-CRIT) should maximize the likelihood of accepting accurate estimates from a suite of specimens influenced by MD behavior. The models, methods, and data presented here provide the means to objectively define data selection and demonstrate the effectiveness of a given set of criteria. Such approaches are vital, if we wish to remove the arbitrariness that hinders the identification of reliable paleointensity data.

关键词： paleointensity Archeointensity Multidomain Non-ideal behavior

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Is there a precursor to the Cretaceous normal superchron? Ne...

Reply to comment by *** on“Experimental reassessment of the Shaw paleointensity method using laboratory-induced thermal remanent magnetization”

中国科学院地质与地球物理研究所2004学术年会

作者： Ching-Hua Lo Department of Geosciences National Taiwan University

Although the geomagnetic reversal record for the past 160 Myr is relatively well documented,whether a precursor exists before the onset of the Cretaceous normal superchron(CNS) remains a contentious topic in the study of the evolution of geomagnetic *** the present study we have tried to find out if new paleointensity data can provide more information about this topic. A paleointensity,geochronologic and paleomagnetic investigation has been conducted on four andesitic basalt lava flows from Hulahada in Liaoning *** *** Ar/Ar dating experiments indicate the volcanism occurred at about 122.7±0.6 *** to marine anomaly *** experiments and hysteresis loops show that the main magnetic carrier of remanence are titanomagnetites with Curie temperatures of～580℃.Thirty-eight samples from three lavas underwent Thellier-Thellier paleointensity experiments with systematic partial thermoremanent magnetization (pTRM) *** samples from the studied lavas yield reliable paleointensity estimates with a mean virtual dipole moment (VDM) of(4.8±0.2)×10 Am,about half the strength of the modern-day *** paleointensity results in conjunction with previous data suggest that there is no precursor to the CNS.

关键词： paleointensity 40Ar/39Ar dating Cretaceous normal superchron Andesitic basalt

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Experimental reassessment of the Shaw paleointensity method using laboratory-induced thermal remanent magnetization

中国科学院地质与地球物理研究所2003学术年会

作者： John Shaw Mimi J.Hill Geomagnetism Laboratory University of LiverpoolLiverpoolUK.

INDEX TERMS:1521 Geomagnetism and Paleomagnetism:paleointensity;,1540 Geomagnetism and Paleomagnetism:Rock and mineral magnetism;1594 Geomagnetism and Paleomagnetism:Instruments and techniques;*** [1]Pan et al.’s[2002]aim was to investigate the reliability of the Shaw paleointensity method[Shaw,1974;Kono,1978;Rolph and Shaw,1985]using basalt samples containing laboratory-induced thermal remanent magnetization as the natural remanent magnetization(NRM).The Shaw method usesalternating field(AF) demagnetization of

关键词： paleointensity Shaw method anhysteretic remanent magnetization alteration P value

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Experimental reassessment of the Shaw paleointensity method ...

A simple model for reconstructing geomagnetic field intensity with (10)~Be production rate and its application in Loess studies

中国科学院地质与地球物理研究所2002学术年会

作者： John Shaw Mimi J.Hill Geomagnetism Laboratory University of LiverpoolLiverpoolUK

Artificial thermoremanent magnetization imposed on natural basalt samples was used to check the reliability of Shaw’s palaeointensity method[Shaw,1974;Kono,1978;Rolph and Shaw,1985] and to give an indication of the accuracy of ***,thermal remanence was induced in all samples(50 in total) in a known field(50±0.1 mT).This remanence was regarded as the"original"natural remanent magnetization("NRM").The samples were divided in to three subsets(A, B,and C) and intensity experiments were *** subset of samples used different thermal remanent magnetization(TRM) acquisition ***-magnetic properties on 14 representative subsamples were also measured both before and after the TRM acquisition steps to monitor possible magnetochemical *** has been demonstrated that intensity estimates by the Shaw method give values close to the expected value(50±5mT) in all three sets of basalt *** modified method with Rolph and Shaw[1985]correction,i.e.,using ratios of anhysteretic remanent magnetization given before the TRM step(ARM1) and after(ARM2),is proved to be a powerful approach to correct the TRM capacity changes that result from agnetochemical *** is especially so for sample set C, where the samples were heated up to 700 and then were held at this temperature for 40 min during TRM *** correction,45%of set C samples gave acceptable ***,some samples with strong magnetochemical alteration sometimes invalidated the ARM1/ARM2 ratio correction and gave wrong intensity *** rock magnetic properties is therefore very important when applying the Shaw method.

关键词： paleointensity thermal remanent magnetization Shaw method rock magnetic checks

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Science China Earth Sciences 2008年第6期51卷 855-861页

作者： J. Warren BECK NSF-AMS Laboratory University of Arizona

A simple model for reconstructing the paleomagnetic field intensity with (10)~Be production rate was used for the first time in Loess (10)~Be studies of Luochuan profile. Using the LGM (Last Glacial Maxmium) method, the climatic effects and geomagnetic modulation effects on loess (10)~Be was separated and in turn the 80 ka geomagnetic excursion sequence reconstructed, of which the globally remarkable geomagnetic excursion events such as the Laschamp (42 ka), Mono Lake (32 ka) during the Last Glacial period were revealed and the paleo-geomagnetic intensity curve from Loess (10)~Be over the past 80 ka was quantitatively reconstructed. The reconstructed paleo-intensity fits well with the paleo-intensity curves (SINT200 and NAPIS75), which indicates the significance of global criterion of the (10)~Be paleo- intensity curve and the future direction of loess (10)~Be tracing studies. Results show the irregular vari-ability of the East Asian monsoon precipitation in Loess Plateau is the main cause that has resulted in the ambiguity of the geomagnetic modulation of the (10)~Be record in the loess, and the intrinsic source component of the loess (10)~Be and inherited fraction of magnetic susceptibility (SUS) are characterized by the 'quasi-homogeneous distribution' manner.

关键词： (10)~Be LGM geomagnetic excursion paleointensity quasi-homogeneous distribution

Link between the geomagnetic polarity reversal and global-geology events

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Chinese Science Bulletin 1999年第20期44卷 1843-1851页

作者： Rixiang Zhu Qingsong Liu Yongxin Pan Chinese Acad Sci Inst Geophys Beijing 100101 Peoples R China

The origin of the earth’s magnetic field is one of the five most important unsolved problems in physics, especially geomagnetic polarity reversal remains one of Nature’s most enigmatic phenomena. It is proposed that the geomagnetic polarity reversal links with some global-geology events, although it is difficult to clarify the mechanism of this correlation. The history of continental structures in eastern China would be also linked with some global-geology events.

关键词： geomagnetic reversal paleointensity global-geology event.

DETERMINATION　OF　THE　INTENSITY　OF　THE　EARTHS　MAGNETIC　FIELD　DURING　QUATERNARY　FROM　VOLCANIC　ROCKS　IN　EASTERN　CHINA

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中国科学院大学学报(中英文) 1994年第2期 196-202页

作者： Li Chunjing Zhu Rixiang(Institute of Geophysics, Academia Sinica, Beijing 100101)

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关键词： Wudalianchi paleointensity volcanic lava