【作者】 窦磊；

【导师】 何起祥； 周永青； 董清水；

【作者基本信息】 吉林大学 ， 海洋地质学， 2005， 硕士

【摘要】 海洋第四纪沉积环境和物源分析是海洋地质学家和沉积学家极为关注的问题。第四纪频繁的气候冷暖交替,海平面的频繁波动,在滨海平原区与邻近的陆架浅海区,形成了几十米至数百米的松散沉积层,沉积物中保留了大量反映古环境要素的信息,提取这些信息并分析其地质意义就成为研究者的重要任务。本论文首先对研究海区表层沉积物的沉积类型进行了分类,划分出三个沉积区,通过对每个沉积区沉积物样品的粒度、矿物和元素组成与分布特征的研究,探讨了研究海区沉积物的来源,给出了一定元素示踪的物源意义,并分析了海区的表层沉积物类型、物源及海平面变化对沉积物分布的控制作用。然后又对三个柱状沉积物的类型、粒度、14C年龄和微体古生物在地层中的分布特征进行了分析,并结合浮游有孔虫氧同位素地层划分,探讨了研究海区晚第四纪沉积记录的古环境意义。更多还原

【Abstract】 The North Yellow Sea which besets between Chinese mainland and Korea peninsula is a typical semi-closed shallow sea on continental shelf . In the littoral plain region and the adjacent continental shelf neritic province the incompact sediment layers had come into being since late Quaternary period, the thickness of which is from decades meters up to hundreds meters. Also during this time the climatic changes in temperature are frequent and the sea level changed greatly more than ten times. The sedimentary environment in this area is very complex and the multiplicative benthal sediments forming by the synthetical effect of diversified oceanic force, such as tideway, stormy waves and circumfluence, make up of the unique sedimentary character for this area. Based on the analysis of sedimentology on surface and core sediment of sedimentary area in central continental shelf and geochemistry, the thesis separately analyses the characteristic distributions of modern surface sediment and the lengthways distributions of sediment for different ages. And the significance of ancient circumstance and the information of sources , reflected by the sedimentary character, is elicited preliminarily. All of these indicate that the depositional pattern of study area is mainly controned by the variance of hydrodynamic conditions. Since the granularity constituent of sediment is the most distinctive indicate, which can reflect sedimentary effect, sedimentary circumstance, especially sedimentary driving condition, the thesis make a particular disquisition on the grain characteristic of the surface sediment. The analytic result for 103 grain samples indicates that the sedimentary types of surface sediment include gravelly sand, medium sand, fine sand, very fine sand, silty sand, sand-silt-clay, shaly sand, clayer silt and silty clay. According to the distributing characters of those sediments, the three sedimentary areas are measured off ulteriorly,therer are south silty sedimentary area, northeast sanded sedimentary area, northwest relict sedimentary area. And via analyzing the sediment samples on the granularity, mineral, and the constituent and distributing character of element, it was detected that the sedimentary character of surface sediment are mainly controlled by the sedimentary environments and source. The south area is effected by the water circulation of Yellow Sea, and the hydrodynamic power is more feeblish, so the sediment in this area is relatively fine, the content of heavy minerals is high . And from south to north, the grain is from fine to coarse by degree, which indicates the gradual increasing of hydrodynamic power. The North edge and most of the northeast area is effected by the strong tideway and the sediment are mainly medium sand, fine sand, very fine sand.the sediment in northeast is mainly coarse, the light minerals ’contents of feldspar and quartz are high. Due to the northwest area(section C)is just in the eroding circumstance, the unsymmetrical exposal of sediment in the late Pleistocene results in the different types of embedded sediment, such as very fine sand, silty sand, sand-silt-clay. Since the sample of surface layer only can provide the neoteric information, in order to probe into the ancient geological circumstance of Quaternary period, we must carry through the study of the deep stratum. Therefore, the thesis analyze the typical column sediment on their types, granularities, the age of C14, and the distributing character of the micro-paleontology in the stratum, and discussed the evolutive disciplinarian of ancient circumstance in researching area since late Quaternary period by coalescent with partition of pelagic foraminifer isotope stratum. According to the comparative results of column samples, the samples in researching area opened out the sediment of oxygenic isotope 3rd late phase, oxygenic isotope 2nd phase, and oxygenic isotope 1st phase. In oxygenic isotope 3rd late phase, researching area is delta environment, in oxygenic isotope 2nd phase, that is mainly the sediment environment of sea facies alongshore, such as firth and delta更多还原