【作者】 王凤；

【导师】 方念乔；

【作者基本信息】 中国地质大学（北京） ， 海洋地质， 2014， 博士

【摘要】 U1312B孔位于北大西洋中纬地区，能够灵敏地监视北极冰盖发育程度，记录气候变化特征。论文以IODP306航次U1312B站位上部90m沉积岩芯为研究对象，以G.ruber氧同位素分析为基础，结合碳同位素、G.ruber相对丰度、N.pachyderma（R/L）比值、浮游有孔虫丰度、冰筏碎屑含量、CaCO3百分含量及热释光多种替代性指标，研究了晚上新世以来研究区环境变化特征以及其对冰盖消长的响应过程。经过分析对比，得出以下认识：1、U1312Bδ18O曲线可与全球大洋标准曲线LR04比较，据之建立的4.1Ma以来的地层表可为IRD带南缘的古海洋学研究提供年代分析的基础。2、研究区δ18O记录与其他环境指标的变化情况表明，中更新世转型在研究区存在显著表现。在971kaBP之前，气候主导周期以41ka为主，在971~696kaBP，气候主导周期由41ka和100ka周期共同作用，在696kaBP之后，100ka周期为显著气候主导周期。3、U1312B冰筏碎屑记录了北极冰盖活动对中纬地区的影响历史，在2.52Ma首次出现的冰筏碎屑具有重要研究意义，标志着北极冰盖扩张的时间及其影响力。自中更新世转型期以来，冰筏碎屑频繁出现且含有大量的碳酸盐物质，与海因里希事件的高度相似，肯定了北极三大冰盖在短周期时间内消长在末次冰期之前就已经存在，这种新的冰盖消长机制将成为日后研究的重点和热点。4、U1312B站位替代性指标和高纬站位的资料显示出北极锋和北大西洋暖流的变化特征，从而将北极冰盖的形成到扩张过程分为4个演化阶段：4.1~3.6Ma，北大西洋暖流加强期，北极锋处于萌芽状态；3.58~3.3Ma，北极小冰盖或者冰帽开始形成；在3.29~2.86Ma:研究区气候回暖，北极冰盖的影响力主要在58°N附近；2.85~2.5Ma，北极冰盖三大冰盖形成并扩张，其影响力逐步南伸至40°N左右。5、热释光的变化特征显示出其对研究区温度变化的指示意义，其低值/高值与氧同位素曲线的冰期/间冰期旋回对应关系良好。通过单频谱分析和连续小波分析，能够看出热释光对地轨周期的积极响应。热释光作为古海洋替代性指标具有可行性。更多还原

【Abstract】 Since the late Pliocene global climate changed drastically as the arctic ice sheetsformation and expansion. It remains controversial about its evolutionary process.Integrated Ocean Drilling Project (IODP) Expedition306Site U1312B is located atthe south of IRD belt,its upper90m sediment records the history about the growth anddecline of the arctic ice sheets in detail.We use several proxies:G.ruber δ18O and δ13C、G.ruber relative abundance、N.pachyderm（aR/L）、Planktonic foraminiferal abundance、Ice-rafted debris(IRD) content、CaCO3content and Thermoluminescence to reflect thepalaeoenvironment changes The following results have been achieved.1.According to the comparison between U1312B δ18O and LR04,we establish4.1Ma age framework for the IRD belt age analysis.2.The U1312B proxies change characteristics show the positive response to theMid-Pleistocene Transition (MPT).which began971kaBP and was complete by696kaBP Before MPT, the dominant cycle is41ka, during the MPT,the dominant cyclesare41ka and100ka,after the MPT the dominant cycle is100ka..3.The first appearance IRD at2.52Ma indicates the arctic ice sheets expand largeenough to affect the mid-latitude at this time. Since the MPT, the high frequentappearance of IRD which is composed of plenty of carbonate confirm that theHeinrich-Like Events exist before the Last Glacial period. The arctic ice sheet growthand decline mechanism in short cycle will be the principal research focus in thefuture.4.The arctic ice sheet from the formation to the expansion process can be dividedinto four evolution stages:4.1~3.6Ma, the arctic ice cap was in inchoate period;3.58~3.3Ma, the arctic ice cap began to form;3.29~2.86Ma the arctic ice sheet hadbeen formation but it influenced mainly near the58°N area;2.85~2.5Ma, the arcticice sheet expanded large enough to influence the mid-latitude area.5.Thermoluminescence change characteristics show the instructions of thetemperature change in the study area,its the low/high value fit oxygen isotope glacial/interglacial stage very well.Its change characteristics responds positively to theearth orbital cycles. It is reliability that thermoluminescence is feasible alternativeproxy of the paleooceanography.更多还原