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1、Introduction黄土堆积不仅仅局限于黄土高原，黄土高原以外的地区，包括中W西北、东北、南方，都有广泛发育的黄土堆积。今年来，长江中下游的下蜀黄土是研究热点,这一地区地处北半球热带，该地的黄土堆积保存了至少自晚渐新世以来的气候变化记荣。学者们参照研宄黄土高原黄土的方法，对长江不游的黄土的各项指标做了详细的研宄，包括grain-sizecharacteristics,claymineralassemblage,chemicalweathering,lipidbiomarkers(Xieetal.,2003)andenvironme
2、ntalmagnetism(Zhangetal.,2007,2009)，同位素等，用来反映自更新世以来的气候变化。物源研究将冇助于我们更好的解释这些古环境指标，理解第四纪以来中国气候环境的变化。BesidestheChineseLoessPlateau(CLP)innorth-centralChina,loessdepositsarealsodistributedinnorthwestern,easternandsouthernChina.Recentyears,theXiashuloessinmiddleandlowerreache
3、sofYangtzeRiverhasattractedincreasingattention.XiashuloessdepositsinthesubtropicalregionsontheNorthernHemisphere,preservingclimaterecordssinceatleast0.85MaBP.ReferringtothemethodofstudyingloessonCLP,researchershaveinvestigatedmanyproxiesofXiashuloess,includinggrain-size
4、characteristics,claymineralassemblage,chemicalweathering,lipidbiomarkersandenvironmentalmagnetismelementratios.TheseproxiescouldreflectthepaleoenvironmentandclimatechangesinthisregionsincemiddlePleistocene.Sourceidentificationwilldefinitelyhelptointerpretthesepaleo-prox
5、ies长江中下游黄土的物质源区存在争议。主要存在两种不同的观点。基于粒度、磁化率、沉积分布的证据，一些人认为南方黄土与黄土高原黄土有着和似的源区，南方黄土主要由冬季风从中国北部、两北吹来。南方黄土堆积是两北源区干旱程度加剧，冬季风加强，与青藏高原隆升、西风急流南移有关。但是，南方黄土中含有很多32um的颗粒，风尘不可能搬运这么远的距离；南京黄土与黄土高原黄土同定元素比率与主要元素组成也存在较大差异，表明南方黄土与黄土高原黄土的源区不同。所以也有人认为南方黄土是当地物质的再沉积。南方黄土可能反映了冰期阶段北半球亚热带地区干早程度加剧以及
6、冬季风加强。ThesourceofXiashuloessinmiddleandlowerreachesofYangtzeRiverremainscontroversial.Thereexistmanilytwodifferentopinions.Basedontheevidenceofsedimentdistributionsandgrain-sizefeatures,someresearcherthinkthesourceofXiashuloessissimilartothatofloessonCLP.TheXiashuloessm
7、aterialsweremainlyblownfromthedesertsinnorthernChina.TheformationofXiashuloesswastheresultofincreasingacridityofinnortherndustsourceareasandstrengtheningofEastAsianwintermonsoon,withreferencetoupliftoftheTibetanPlateauandthesouthwardshiftofpolarjetstream.Thesouthernloes
8、scontainsalargeproportionofparticleslargerthan32nm,whichseemsunlikelytobetransportedbywindforsuchalongdistance
