Unconformity is an important part of hydrocarbon migration system and a favorable place for hydrocarbon accumulation. Taking the northern Bozhong Sag in Bohai Bay Basin as an example, we analyzed the characteristics of unconformity development on bottom Paleogene and its influence on hydrocarbon accumulation comprehensively by using the data from 3D seismic, drilling and logging, and core thin-section.Results show that there are five contact types and seven structural types of the Paleogene bottom unconformity in the northern Bozhong Sag.Unconformity channel types can be divided into double migration channel type Ⅰ, single migration channel type Ⅱ 1 and Ⅱ 2 and plugging type Ⅲ. The single migration channel type Ⅱ 1 is the main type of unconformity hydrocarbon accumulation in the study area. The migration and accumulation types include lateral type, trap and lateral type, vertical and lateral type, and plugging type. The hydrocarbon migration capacity of sandstone above the unconformity is related to the microscopic characteristics of sandstone and the dip angle of fracture. The hydrocarbon migration and storage capacity of semi-weathered rock strata are controlled by the volcanic rocks with good original porosity and permeability and difficult to form weathered clay layer.
Two-stage cultural layers（40～37 kaBP and 30～29 kaBP） were identified in the Chuanfan Cave, Wanshouyan Site, Sanming, Fujian Province. The artificial pebble-laid living surface in the first cultural layer was an important discovery in paleolithic reconnaissance, which has great significance in investigating the living environment in the last glacial period. Systematic phytolith analysis of deposits in the Chuanfan Cave provided us an opportunity to reveal climatic change and the living environment of ancient humans since late Pleistocene. Results show that acicula and rhabdolith were dominant in all samples, followed by fan-shaped and blocky phytolith, and more saddle-shaped phytolith in short cell. Five climatic stages were divided from bottom to top according to phytolith assemblages: cool dry, cold dry, in relatively dry cold,relatively dry cool, and relatively warm dry. The first ancient human lived in the early stage Ⅰ, which was relatively warm in cool-dry background. The second ancient human lived in the late stage Ⅳ, which was relatively warm in cool-relatively-dry background. Phytolith variation also indicated that the Heinrich events H4 and H3 correspond well to the two cultural layers. The climate tended to be cooler rapidly after the two Heinrich events, which changed the living environment of ancient humans and shall be the main reason for the ancient humans in the two stages to escape from the Chuanfan Cave.
在全球变暖的背景下,台风活动在未来如何发展是关系到人类社会安全的重大问题之一.受器测记录时间长度的限制,我们对于台风长期的发展与演化机制的认识还不充分.从东海内陆架泥质区的沉积记录中提取台风信息,是了解几千年来影响我国的台风演变规律的有效手段.但是,其他极端事件,尤其是冬季寒潮,会影响台风沉积事件识别的准确性.台风与冬季寒潮大风沉积事件的辨识也是台风活动重建的难点之一.利用布放在东海内陆架泥质区的四脚架观测系统,分别获取了台风"天鹅"和冬季寒潮大风期间的海水温度、盐度、悬浮体浓度和海流等数据,并结合近海观测浮标的风速、风向和波浪等数据,探讨了台风与冬季寒潮沉积动力过程的差异.结果表明,台风与冬季寒潮在风向、有效波高和近底层流速变化上有一定的相似性,但是台风较高的强度更容易引起近底层沉积物的再悬浮;台风经过时,高浓度悬浮体主要来自海底沉积物的再悬浮,而冬季寒潮期间高浓度悬浮体与长江入海物质的输入有关.由于台风和冬季寒潮近底层海流流向的差异,在东海内陆架泥质区向海一侧边缘沉积记录中的砂层可能代表了台风事件沉积,是研究台风活动规律的良好研究材料.研究结果为从东海泥质区沉积记录中提取更准确的台风信息提供了科学参考.
俯冲带是地球上最大地震的发源地.俯冲板块正断层为海水进入上地幔,引起蛇纹石化提供通道,其地震可能引发大海啸.研究其动力学机制,对推动俯冲带动力学过程研究及保护人类生命安全都具有重要意义.本文综述了西太平洋汤加海沟、马里亚纳海沟、伊豆-小笠原海沟和日本海沟俯冲板块外缘隆起带到海沟附近的正断层分布与变形特征,定量化阐明了地球动力学模拟方法揭示的西太平洋俯冲板块正断层形成过程.研究发现汤加海沟和马里亚纳海沟的正断层平均断距最大;俯冲板片有效弹性厚度变化直接影响正断层形成区域,而有效弹性厚度与板块年龄相关性较大.本文系统性回顾了西太平洋俯冲动力学研究并且提出了对未来相关研究的启示.
采用从深海沉积物样品中分离培养的海洋微生物,分别进行几种海洋细菌(Jeotgalibacillus sp.,Paenisporosarcina sp.,Sulfitobacter sp.)对稀土元素Ce的富集成矿过程的模拟实验.实验过程中利用ICP-MS、SEM、TEM等分析测试手段考察了微生物与稀土元素的相互作用过程.结果表明,三种海洋细菌对稀土Ce都有吸附富集作用,海洋细菌吸附富集稀土元素Ce的效率主要与细菌密度和稀土元素浓度有关,不同的海洋细菌对稀土元素的富集能力也有所不同.海洋细菌吸附富集稀土Ce并矿化的过程中,稀土元素Ce首先被吸附在细胞表面形成成核点,随后在细胞表面被矿化形成含稀土Ce的非晶相结构的矿物颗粒.通过考察海洋细菌对稀土Ce的生物成矿过程,进一步探讨了海洋微生物富集稀土成矿的过程和作用机制.
