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Paleomagnetic Excursions Recorded in the Yanchi Playa in Middle Hexi Corridor, NW China Since the Last Interglacial
作者姓名:YANGTaibao  YUYongtao  LIJijun  ANCongrong  LIUJinfeng  ZHANGJunyan
作者单位:[1]KeyLaboratoryofWesternEnvironmentalChanges,ChineseMinistryofEducation,LanzhouUniversity,Lanzhou730000China [2]DepartmentofGeography,SchoolofGeosciences,NanjingNormalUniversity,Nanjing210097,China [3]InstituteofGeologyandGeophysics,ChineseAcademyofSciences,Beo'ing100029,China
摘    要:Paleomagnetic determinations on lithologieal profiles of two paralleled long drillin gcores 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-40.5kyr), Gaotai Event (82.8 kyr-72.4 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). Here, we tentatively propose that these geomagnetic excursions/reversals can be viewed as precursors to climate abruptness. During the transitional stages when the earth‘s magnetic field shifted between a temporal normal and a negative period, the earth‘s 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 earth‘s 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.

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Paleomagnetic excursions recorded in the Yanchi Playa in middle hexi corridor,NW China since the last interglacial
YANGTaibao YUYongtao LIJijun ANCongrong LIUJinfeng ZHANGJunyan.Paleomagnetic Excursions Recorded in the Yanchi Playa in Middle Hexi Corridor, NW China Since the Last Interglacial[J].Journal of Mountain Science,2004,1(2):128-142.
Authors:Yang Taibao  Yu Yongtao  Li Jijun  An Congrong  Liu Jinfeng  Zhang Junyan
Institution:(1) Department of Geography, School of Resources and Environmental Sciences, Lanzhou University, 730000 Lanzhou, China;(2) Key Laboratory of Western Environmental Changes, Chinese Ministry of Education, Lanzhou University, 730000 Lanzhou, China;(3) Present address: Department of Geography, School of Geosciences, Nanjing Normal University, 210097 Nanjing, China;(4) Institute of Geology and Geophysics, Chinese Academy of Sciences, 100029 Beijing, China
Abstract: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.
Keywords:Paleomagnetism  geomagnetic excursion  the Late Pleistocene  arid Northwestern China
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