High Resolution Oxygen Isotope Stratigraphy for the Last 150,000 Years in the Southern South China Sea: Core MD972151

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Title:	High Resolution Oxygen Isotope Stratigraphy for the Last 150,000 Years in the Southern South China Sea: Core MD972151 南中國海南部巖心MD972151之過去十五萬年高解析度氧同位素地層
Authors:	李孟陽 Meng-Yang Lee 魏國彥 Kuo-Yen Wei 陳于高 Yue-Gau Chen
Contributors:	臺北市立教育大學自然科學系
Keywords:	South China Sea Oxygen Isotope Late Quaternary Chronology
Date:	1999
Issue Date:	2009-07-31 11:22:40 (UTC+8)
Abstract:	This study presents the directional paleomagnetic secular variationpattern of core MD972151 taken from the southwestern South China Seaduring the IMAGES Ⅲ-IPHIS Cruise in 1997.A total of 281 samplestaken from this core were subjected to AF demagnetization to analyze theircharacteristic remanent magnetization.The results indicated a reversed event at depth of between 21.7 and23.8 meters.It was identified as the Blake Event,and has an age interval ofabout 130ka.Another short reversed event was found near the bottom ofthe core.This was tentatively described as an excursion that occurred atabout 150-160ka.These assignments were in very close agreement with theresults of oxygen isotope analysis.Consequently,the core under study wasdetermined to be presenting a record of perhaps the last 160ka probably.And the sedimentation rate can thus be estimated to be of about 17-18cm/ky.In addition to the reversed events,two excursions were also observed,one at the core top to 3.7 meters,and the other at 15.3-15.5m in depth.Thelatter excursion was estimated to be of about 75ka in age,based on comparingthe results of this study to the intensity record made by Valet andMeynadier(1993).However,the former one might well be a recent excursion, under 20ka in age,because comparison with oxygen isotope dataruled out the possibility of being the'Laschamp Event'.Another possiblecause for this abnormal event might be that it was due to deposition processof the sediments.Of course,this question will require further study.Finally,the paleo-longitude variation pattern shows that the VGPsseemed to drift eastward at a record rate of over 4 meters in depth.Thisdeparts from observations of the present-day geomagnetic field that indicate the magnetic pole is drifting westward.The significance of this discrepancy warrants further study too.
Relation:	Terrestrial, Atmospheric and Oceanic Sciences, 10卷(1), p.239-254
Appears in Collections:	[Department of Applied Physics and Chemistry] Periodical Articles

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