【作者】 王箫风；

【导师】 郑祥民；

【作者基本信息】 华东师范大学 ， 第四纪地质学， 2007， 硕士

【摘要】 中国第四纪黄土，以广泛的分布性、沉积时代的连续性和对全球环境变化事件和古气候演变反应的敏感性，在第四纪古环境研究中具有重大的意义。分布在环渤海地区的山东黄土、东海岛屿和海底的风尘黄土及其次生产物也是我国第四纪风成堆积的重要组成部分，它们是我国第四纪黄土沉积物中的一种独特类型。本项研究以山东长岛岛屿黄土与东海岛屿黄土剖面作为研究对象，进行粒度、环境磁学、碳酸盐以及CBD等研究，所得的主要成果和结论包括以下几个方面：1．长岛黄土属于砂质粘土至亚粘土类型，嵊山岛黄土与浪岗山岛黄土都属于粉质粘土至粉质亚粘土类型。通过将长岛黄土与浪岗山黄土、嵊山以及洛川马兰黄土的颗粒组成进行对比，发现长岛黄土与各地黄土的各粒级的含量都比较接近，且粒度组成均是以粉砂为主，是黄土粒度组成的众数组；而粘粒次之，符合我国黄土粒度组成的基本特征。与洛川黄土相比，长岛黄土、嵊山岛黄土和浪岗山岛黄土的砂组分明显增多，反映前三者的黄土可能都接受了一部分“近源”沉积。2．长岛黄土剖面磁性矿物的含量总体不高，剩磁载体以亚铁磁性矿物为主，磁性矿物的粒度主要以细粒为主。嵊山岛黄土磁性矿物含量较少，剖面上部约60cm经历了较强的成壤和风化作用，以不完整反铁磁性矿物为主，剖面中部以稳定单畴磁性颗粒对磁化率贡献最大，下部则以多畴和超顺磁颗粒共存。浪岗山黄土磁性矿物含量也不大，对磁化率贡献较大的是多畴磁性矿物，同时不完整反铁磁性矿物含量也有较大比重。东部岛屿黄土的磁性矿物含量较低，最高值明显低于典型黄土-古土壤序列中黄土段的磁化率最高值，表明其物质来源与内陆有异；而最低值却与各地黄土层磁化率的最低值相似，大都在30×10^-8m³kg^-1左右，有研究表明，沙漠物质或砂质粉尘的磁化率也为30×10^-8m³kg^-1左右，证明了各地黄土物质来源的一致性，这反映了这些地区黄土的来源有可能和陆架沙漠化有关，强劲的古季风活动导致了西北沙漠群的形成，同时也可以导致陆架的沙漠化，陆架的沙漠化又衍生了近源的黄土堆积，与西北内陆的物源是有可能是不一致的，但形成的过程和方式上是相似的。3．长岛磁化率和成壤作用强度具有良好的对应关系，磁化率与成壤化作用强度成正比，可以作为古夏季风的代用指标。嵊山岛黄土中亚铁磁性矿物的含量较黄土高原低，主要的磁性矿物为磁铁矿、磁赤铁矿、赤铁矿、针铁矿，土壤中磁化率的变化主要受成壤成因的细颗粒亚铁磁性矿物控制。4．经过CBD处理，长岛和浪岗山黄土磁化率值平均降低了65％、67％，远远低于嵊山黄土的80％。其中古土壤层降低幅度较大，黄土层降低的幅度较小。CBD处理后的黄土和古土壤层的磁化率值接近，暗示了黄土在堆积过程中物源变化不大。其中古土壤层降低幅度较大，反映了古土壤在成壤作用过程中经历了较强的成壤作用。更多还原

【Abstract】 Loess deposition is a special kind of dust-sediment that came into being under particular environment in quaternary period. Loess deposition in China is widely distributed ,continuously deposited abd sensitively responded to paleo-environment and paleo-climate changes.So it is of great theoretic significance to study loess in Quaternary research . Systemic and overall researches are made on the loess,which is one kind of good carriers of paleo-environmental information of land, It has been an agreement that loess on Plateau is the sediment of aeolian dust. All of the proxies which are used in the research of loess distributed in Northwest China to reflect the variation of paleoclimate have been widely used in the research of Eastern Islands Loess For the reason of thin stratum and the great effects made by contemporary environment, it is an valuable research whether the proxies which are widely used in northwest to reflect paleoclimatal fluctuations could be used in the loess research successfully in those area. Paleo-environmental changes and the sedimentary mode of loess on islands are discussed in this paper and compared with the three profiles of Changdao Island and Islands of East China Sea on the proxies of grain size, magnetism ,CaCO₃ and CBD. Results and acknowledgements of this paper include five aspects as follows:1.The grain size composition of the Aeolian loess on Changdao island is basically consistent with that of other inland loess in China .Through the analysis of experimental outcome of grain size , it’s confirmed that the three profiles have the same components carried by wind which consistent with the rule of belt distribution about Loess in China .The sendy grain content of Changdao Loess is higher than that in Islands of East China Sea, The loess in Changdao island belongs to sendy-clayey soil deposition ,while the loess in islands of East China Sea belongs to clay-clayey soil deposition. They all coincide with that sandy-loess zone ,loess zone and clayey-loess zone distribute from west to east in China. Compared with that of other inland loess ,the content of sendy grains of the three loess profiles is relatively higher ,it indicates that the study profiles received not only far Aeolian deposition from northwest by strong winter monsoon as other inland loess but also proximal one from inshore shelf area during the last glacial age. And the content of sendy grains of the loess can be regarded as an index that shows the proportion of Aeolian deposition.2.The content of magnetic minerals of loess on Changdao Island is less comparatively and the ferrous-magnetic minerals play a leading role. The top part of Shengshan about 60cm thickness of the profile contains more anti-ferromagnetic minerals which indicates the violent pedogenesis and weathering. Concentration of stable singe domain magnetic mineralscauses the increase of magnetism in the middle part of the profile And Super-paramagnetic and multidomain minerals dominant the components of loess at the bottom of this profile,different from which it’s the multidomain minerals cause the increase of magnetic susceptibility in Langgangshan Islands profile. The content of magnetic minerals of the three profiles are obviously lower than typical loess profile ,it shows that the matter source is different from inland .But the lowest is about30× 10^-8m³kg^-1 ,which is similar to other inland areas, it indicates that the loess source of each area is consistent and it probably relates to land-desertification..3.The magnetic minerals formed during the process of pedogenesis are dissolved by CBD（Citrate-Bicarbonate-Dithionite）which indicates that CBD can be used better to reflect variation of paleoclimate in Changdao loess and loess in Shengshan Island and Langgangshan island even its pedogenesis verlapped with contemporary pedogenesis.Comparing the parameters of loess pre-CBD and post-CBD,it’s found out that the magnetic minerals CBD dissolved are not only SP,but SSD and even PSD magnetic minerals. After dissolved by CBD, the main components of magnetic minerals in loess are MD magnetic minerals.4.The change of magnetic susceptibility of loess from Northwest China to East China after dissolved by CBD matches the change made by wind transport.From the conclusion above, it can be concluded that CBD technology may be better used to distinguish the size of magnetic minerals.更多还原