资源描述：
《holocene east asian monsoon precipitation pattern》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。
1、EarthandPlanetaryScienceLetters233(2005)467–479www.elsevier.com/locate/epslHoloceneEastAsianmonsoonalprecipitationpatternrevealedbygrain-sizedistributionofcoresedimentsofDaihaiLakeinInnerMongoliaofnorth-centralChinaYanjiaPenga,JuleXiaoa,T,ToshioNakamurab,BaolinLiuc,YoshioInouchidaI
2、nstituteofGeologyandGeophysics,ChineseAcademyofSciences,P.O.Box9825,Beijing100029,ChinabCenterforChronologicalResearch,NagoyaUniversity,Nagoya464-8602,JapancNationalLabonScientificDrilling,ChinaUniversityofGeosciences,Beijing100083,ChinadDepartmentofEarthSciences,FacultyofScience,E
3、himeUniversity,Matsuyama790-8577,JapanReceived24August2004;receivedinrevisedform14January2005;accepted14February2005Availableonline12April2005Editor:E.BoyleAbstractTwosedimentcoresrecoveredinthecentralpartofDaihaiLakeinnorth-centralChinawereanalysedat2-to4-cmintervalsforgrain-sized
4、istribution.Grain-sizedistributionsofthelakesedimentsareinferredtobeaproxyforpastchangesinEastAsianmonsoonprecipitation,suchthatgreatersilt-sizepercentageandhighermediangrainsizereflectincreasedmonsoonalprecipitationrates.Thegrain-sizerecordofDaihaiLakesedimentsspanningthelastca10,
5、000yrindicatesthatthemonsoonalprecipitationinthelakeregioncanbedividedintothreestages:theEarly,MiddleandLateHolocene.DuringtheEarlyHolocenebeforeca7900calyrBP,themediangrainsize(Md)andthesilt-fractioncontentwererelativelylowandconstant,suggestingrelativelylowprecipitationoverthelak
6、eregion.TheMiddleHolocenebetweenca7900and3100calyrBPwasmarkedbyintensifiedandhighlyvariablemonsoonalprecipitation,asindicatedbyhighandvariableMdvaluesandsiltcontentsofthelakesediments.Duringthisperiod,averageprecipitationrategraduallyincreasedfromca7900to6900calyrBP,displayedintens
7、eoscillationsbetweenca6900and4400calyrBP,andexhibitedadecreasingtrendwhilefluctuatingfromca4400to3100calyrBP.AlthoughgenerallyhighduringtheMiddleHolocene,boththeMdandthesiltcontentassumeddistinctlylowvaluesattheshortintervalsofca6500–6400,6000–5900,5700–5600,4400–4200calyrBP,implyi
8、ngthatmonsoonalprecipitati
