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Paleomagnetic excursions Recorded in the Yanchi Playa in Middle Hexi Corridor, NW China Since the Last Interglacial

Journal of Mountain Science 2004年第2期1卷 128-142页

作者： YANGTaibao YUYongtao LIJijun ANCongrong LIUJinfeng ZHANGJunyan KeyLaboratoryofWesternEnvironmentalChanges ChineseMinistryofEducationLanzhouUniversityLanzhou730000China DepartmentofGeography SchoolofGeosciencesNanjingNormalUniversityNanjing210097China InstituteofGeologyandGeophysics ChineseAcademyofSciencesBeo＇ing100029China

Paleomagnetic determinations on lithological profiles of two paralleled[( )-275(long )]drilling cores covering the past 130 kyr B.P., GT40 and GT60, from the Yanchi Playa in the arid Northwestern China, indicate that a series of pronounced paleomagnetic excursions have been documented. By correlating our results with published regional and worldwide reports, 4 excursion events out of 10 apparent reversal signals (labeled from GT-1 to GT-10) were identified as excursion events coeval with the Mono Lake Event ([(28.4)( )]kyr~[(25.8)( )]kyr), Laschamp Event ([(43.3)( )]kyr^40.5 kyr), Gaotai Event (82.8 kyr~[(72.4)25( )]kyr) and the Blake Event (127.4 kyr^113.3 kyr), respectively. GT-9 correlates with the above-mentioned Gaotai Event, GT-7 and GT-6 correspond to two stages of the Laschamp Event and GT-5 to the Mono Lake Event. It is noteworthy that the so-called Gaotai Event has not been reported as a pronounced paleomagnetic excursion in the Northwestern China. Every magnetic excursion event corresponds to paleointensity minima, anteceding those established abrupt paleoclimatic change events, such as the Younger Drays and the Heinrich Events (H1-H6)[(. )-250( )]Here,[( )-250( )]we tentatively[( )-250( )]propose that these geomagnetic excursions/reversals can be viewed as precursors to climate abruptness. During the transitional stages when the earths magnetic field shifted between a temporal normal and a negative period, the earths magnetic paleointensity fell correspondingly to a pair of minima. Although more precise chronology and more convincing rock magnetic parameter determinations are essentially required for further interpretation of their intricate coupling mechanism, these results may have revealed, to some extent, that the earths incessantly changing magnetic field exerts an strong influence on the onset of saw-tooth shaped abrupt climate oscillations through certain feedback chains in arid Central Asia or even North Hemispheric high latitude regions.

关键词： Paleomagnetism geomagnetic excursion the Late Pleistocene arid Northwestern China

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Paleomagnetic results of Core NP93-2 from the Prydz Bay,Eastern Antarctica

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Chinese Journal of Polar Science 1996年第1期7卷 34-40页

作者：王保贵候红明汤贤赞袁友仁

Two reversal geomagnetic excursions are detected by systematically paleomagnetic measurements of the Core NP93-2 from the Prydz Bay, Eastern *** is found in 60 to 67.5 cm from the tOP of the core, and the 14C dating age of layer 67.5 cm to 72.5 cm is 10315±800 a *** is estimated that the geomagnetic excursion occurred at 9980-8880 a B.P.,and perhaps was the record of the Gothenburg geomagnetic excursion (about 12000 a B.P.).The other is found in 27.5-32.5 cm,and the 14C dating age is 5390±600 a B.P., with which no generally acknowledgedgeomagnetic excursion can be compared. But a few reports of geomagnetic excursions can be used for comparing with,Zhu et *** a geomagnetic excursion at 4980-4770 a *** peat in Beijing, Wang et *** a geomagnetic excursion at5120±110 a *** Core NS-89--76 in Nansha Waters and Zhou et al. reported ageomagnetic excursion at 6400-6000 a *** Core QC2 in Yellow Sea. Whetherthe studied geomagnetic excursion does exist or whether those reported geomagnetic excursion are the same one is worth further study.

关键词： paleomagnetic geomagnetic excursion Eastern Antarctica Prydz Bay

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geomagnetic episodes of the last 1.2 Myr recorded in Chinese loess

Geomagnetic episodes of the last 1.2 Myr recorded in Chinese...

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中国科学院地质与地球物理研究所2002学术年会

作者： Y.X.Pan,~a R.X.Zhu,~a Q.S.Liu,~b B.Guo,1 L.P.Yue,~c and H.N.Wu~c a.Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing China b.Institute for Rock Magnetism,University of Minnesota,Minneapolis,USA c.Department of Geology,Northwest University,Xi’an,China.

The Matuyama-Brunhes(M/B) boundary,termination of Jaramillo normal subchron (J/M) as well as three young geomagnetic excursions has been revealed in the Weinan loess section [Zhu et al.,1994,1998,1999].Recently,we carried out further paleomagnetic directional studies on the same section and recovered the onset of the Jaramillo normal subchron(M/J) and four geomagnetic excursions,two in the Brunhes and two in the late *** fact that all seven excursions found in this section are in loess units and expected excursions in paleosols are not found suggests that short-lived geomagnetic signals could be only recorded in loess units,and may have been fully smoothed or wiped out in paleosol units by strong *** by a new astronomical timescale(HLD00),ages of the geomagnetic excursions and reversal boundaries have been *** tentatively correlated these excursions with previous results,indicating that a large lock-in model may not be correct for the whole loess profile,although some apparently big positive age discrepancies were observed for the main boundaries.

关键词： geomagnetic excursion Chinese loess 1.2 Myr

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