【作者】 金秉福；

【导师】 林振宏；

【作者基本信息】 中国海洋大学 ， 海洋地质， 2003， 博士

【摘要】 第四纪晚期，由于末次冰期的出现，中国大陆东部海陆分布发生重大变化。分析末次冰期东海沉积物来源，对揭示古陆、古海洋水文状况、气候变化和环境演化都有重要意义。以Q43岩心为代表的东海南部外陆架上层沉积物，是末次冰期海退层序中，滨岸相-滨外浅水相沉积。碎屑矿物风化程度低，磨蚀不显著，分选较差，河流砂特征明显，沉积物来自于近源，由河流输送入海，海洋改造不十分强烈，由于物源供应不足，沉积速率较低。在外陆架水动力的作用下，重矿物有一定富集，重矿物以角闪石—绿帘石矿物组合为特征，含有一定量自生矿物(黄铁矿和海绿石)，稳定矿物少，矿物成熟度低。通过碎屑矿物判断，原岩应是中酸性岩浆岩和浅变质岩类。钛铁矿等有用矿物在细砂层位中出现较厚的砂矿异常，显示一定的浅海砂矿资源潜力。粘土矿物组合为伊利石、绿泥石、高岭石和蒙皂石，伊利石含量占绝对优势，其结晶度指数(Hw)较高，反映东海南部外陆架粘土形成于寒冷干燥的气候环境。 元素地球化学特征表明，元素的丰度受沉积物粒度控制明显。柱样中细粒级(＜0.063mm)元素含量较粗粒级(＞0.063mm)高，变化幅度大，从元素之间相关性来看，粗粒级的元素之间相关系数高，表明粗粒级物质具有统一来源。岩心中元素的垂直分布不仅与寄主矿物有关，而且与沉积环境关系密切。一些元素对比值较好地反映了物源和环境随时间的变化。球粒陨石标准化后的稀土元素具有与长江、黄河、黄土等上陆壳沉积物相一致的特征。长江、黄河晚更新世沉积物与现代沉积物之间，具有一定的差异性，但相似性明显，反映出两河物源特征的稳定性。通过对东海外陆架样品的稀土元素和Sc，Th，Ti等不活泼元素地球化学物源示踪指标对比，再结合沉积学和矿物学特征，判断末次盛冰期与盛冰期以前的沉积物具有不同的物质来源，不同时期的沉积物都具有混合物源的性质，盛冰期东海南部外陆架沉积物受长江物源影响较小，可能来源于距东海南部较近的浙闽沿海山地。 冲绳海槽沉积物的化学特征受控于物质来源，用元素对Al的散点图可以明显显示冲绳海槽物源供应具有阶段性变化的特点。末次盛冰期冲绳海槽中部陆源物质来源于东海陆架，元素地球化学特征显示这些沉积物主要来源于古长江的入海物质。更多还原

【Abstract】 As a result of the sea-level drop at the Last Glacial Maximum in the late Quaternary, the distribution of the land and sea in the eastern China continent changed a lot. The studies to exhibit the sedimentary source in the East China Sea during the last glacial age are of great significance to reveal the hydrologic situation of paleo-continent and paleo-ocean, climate change and environmental evolution. The upper layer sediment of core Q43 in the outshelf of the southern East China Sea shows that it is the regressive sequence of littoral facies to offshore facies and of representative significance. The sediments in the core are weakly weathered, lightly abraded and bad sorted, they have the same feature as river sediment, which is derived from near source and did not experience seriously transformation by ocean. Due to the rate of insufficient sediment supply the sedimentation rate is low. Under the hydrodynamitic condition in the outshelf heavy minerals are enriched to a certain extent. They are of horablede-epidote assemblage and contain some authigene ( pyrite and glauconite ). The content of stable mineral is small and mineral maturity index ( TRZG/HP ) is low. Based on studies of detrital minerals it is unraveled that the coarse-grained sediments are of single and stable source and have the same trait as intermediate-acidic granite and metamorphites. Beneath the relic sand of the outer shelf there is high grade of valuable heavy mineral sand ( for example ilmenite ) reaching the II anomaly order of marine placers and it is of potential resource prospects. Clay minerals are of illite, chlorite, kaolinite and smectite assemlblage. The content of illite is very high and its crystallinity index is high too, which indicate the cool and arid climate condition in the time of sediment conformation.The elemental geochemistry characteristics indicate that elements abundance is controlled seriously by grain size of sediment. The element content in the fine-grainedfraction ( <0.063mm) of the core is great. The correlation coefficient between the elements in the coarse-grained is high, which indicate that the coarse-grained sediments derived from the same provenance. The elements vertical distribution in the core is not only related to the host minerals, but also closely to sedimentary environment. Ratios of some selected element can indicate the change of source and the change of environment with time. Chondrite normalized REE distribution patterns for the core Q43 are comparable to those of the sediment of Changjiang River and Huanghe River delta. The geochemical characteristics of the sediment between the late Pleistocene and modern in Changjiang River and Huanghe River are different, but their similarity is quite remarkable which suggested that the two great rivers are of stable sedimentary sources. Comparison of the characteristic parameters of immobile elements, such as REE, Sc, Th, Ti etc and of the characteristics of sedimentology and mineralogy comes to a conclusion that the provenance of the sediment is different in the Last Glacial Maximum and in the sub-interglacial stage, and they have the traits of mixed source. During the Last Glacial Maximum the sediment in the outshelf of the southern East China Sea was affected weakly by Changjiang River and they are probably derived from the coast mountains of Zhejiang-Fujian Province, which are near the southern East China Sea.The characteristics of the sediment from the Okinawa Trough are controlled by provenance. Some major and trace elements vs. Al scatter plots show clearly the evolution stage of the sedimentary supply to Okinawa Trough. The provenance of the sediment in middle Okinawa Trough during the Last Glacial Maximum is the shelf of the East China Sea. The characteristics of elemental geochemistry ascertain that the sediment was derived from the paleo-Changjiang River.更多还原