东北太平洋CC区表层沉积物中的微体生物化石研究

本区表层沉积物中的微体生物化石丰富,且分异度较高,反映了热带大洋高生产力的特点。中一方面,保存于海底沉积物中的不同的地质时期的微体生物化石都代表着一段沉积的历史。本文通过对表层沉积物中不同的微体化石的组合特征与分布规律的研究,揭示了该区表层沉积物的沉积类型,只特点以及它们与微体化石之间的关系。     

中国第3次北极科学考察

中国第3次北极科学考察利用"雪龙"号考察船,2008年7月11日从中国上海基地码头起航,先后完成了对日本海、俄霍茨克海、白令海、楚科奇海台、加拿大海盆、门捷列夫海脊等海区的观测考察,圆满完成了所拟定的各项科考计划,历时77 d,于2008年9月25日回到上海.     

北极王湾表层沉积物中的粘土矿物及其对物源与古环境变化的指示意义

Kongsfjorden is a typical fjord on the edge of the ice cap of the Arctic Svalbard-Barents Sea. Its inner bay is connected with a modern glacier front along the direction of the fjord axis with a significant gradient change in the parameters of hydrology, sedimentation, and biology. In summer, ice and snow melt-water and floating ice collapse continuously and thus transport the weathering products on the surrounding land into the sea. Thus Kongsfjorden is regards as a natural laboratory for the study of unique sedimentation in polar fjords under modern glacial-sea water conditions. In this study, fifty-two surface sediments were collected in Kongsfjorden for clay mineral analysis to study the sediment source and sediment-transport process. Our results indicate that clay minerals in the surface sediments from Kongsfjorden are mainly composed of illite, chlorite, and kaolinite, and no smectite is found. Rocks from different periods exposed extensively in the surrounding areas of Kongsfjorden provide an important material basis for clay minerals in the Kongsfjorden. Kaolinite may be mainly derived from the fluvial deposits, weathered from reddish sandstones and conglomerates during the Carboniferous Period.Illite is mainly derived from Proterozoic low-grade and medium-grade metamorphic phyllite, mica schist, and gneiss. While chlorite is mainly from Proterozoic low-grade metamorphic phyllite and mica schist. In the direction from the fluvio-glacial estuary to the sea of the glacier front of Kongsfjorden, illite increase gradually,and the content of kaolinite declines gradually. However, the change pattern of chlorite is insignificant, which may be related to the provenance. Kongsfjorden detritus is mainly transported by the fluvio-glacial streams and icebergs into the sea and deposited in the inner bay. Coarse sediments are rapidly deposited in the glacier front,estuary, and near-shore areas. Clay fraction begins to deposit significantly by 200–400 m after flowing into the sea,which due to the crystal behavior of clay minerals, hydrodynamic condition and flocculation. Kaolinite and chlorite on the south of the bay near the Blomstrandhalv?ya Island is mainly affected by ice-rafted detritus and thus can reveal the trajectory of transportation by the floating ice while entering the sea.     

南海北部晚更新世以来的古海洋环境演化特征——来自N-31柱样的沉积记录

对南海北部N-31柱状样沉积物进行了浮游有孔虫定量分析鉴定、氧碳同位素、碳酸盐含量和粒度测试以及AMS14C测年,并采用古生态转换函数计算了表层海水古温度和温跃层深度,揭示了该海区约55 ka以来的古海洋环境特征.转换函数计算的表层海水古温度结果表明,夏季温度的变化范围为27.0～29.6℃,变化幅度为2.6℃,冬季温...     

西北冰洋楚科奇海台南部08P23孔氧同位素3期以来的古海洋与古气候记录

Multiproxy investigations have been performed on Core 08P23 collected from the Chukchi Plateau, the western Arctic Ocean, during the Third Chinese National Arctic Expedition. The core was dated back to Marine Isotope Stage(MIS) 3 by a combination of Accelerator Mass Spectrometric(AMS) carbon-14 dating and regional core correlation. A total of five prominent ice-rafted detritus(IRD) events were recognized in MIS 2 and MIS 3. The IRD sources in MIS 3 are originated from vast carbonate rock outcrops of the Canadian Arctic Archipelago and clastic quartz in MIS 2 may have a Eurasian origin. Most δ18O and δ13C values of Neogloboquadrina pachyderma(sinistral)(Nps) in Core 08P23 are lighter than the average values of surface sediments. The lighter δ18O and δ13C values of Nps in the two brown layers in MIS 1 and MIS 3 were resulted from meltwater events; and those in the gray layers in MIS 3 were caused by the enhanced sea ice formation. The δ18O values varied inversely with δ13C in MIS 2 indicate that the study area was covered by thick sea ice or ice sheet with low temperature and little meltwater, which prevented the biological productivity and sea-atmosphere exchange, as well as water mass ventilation. The covaried light values of δ18O and δ13C in MIS 1 and MIS 3 were resulted from meltwater and/or brine injection.     

楚科奇海与白令海海洋地质研究进展

1999年7月－1999年9月我国进行了首次北极科学考察，实现了北极地区海洋地质研究零的突破，这次考虑取得了大量的沉积物样品，同时还获得了第一手现场资料。简要介绍了沉积物特性，分布特征，分析了沉积物的物质来源，沉积环境，同时介绍了部分室内研究成果。     

法国“阿塔郎特”号海洋调查船上的重力取样

在海洋地质调查中，如何取得好的沉积物样品是每一位海洋地质学家所向往的，而获得好的沉积物样品的关键又很大程度上取决于先进的海洋调查仪器的使用。法国”阿塔郎特“号海洋调查船上的重力取样管不管在性能上，还是安全性上都瞰称世界上比较先进的取样设备。     

长江水下三角洲沉积物的重矿物分布及组合

对2004年取自长江水下三角洲南部区域的145个表层样品进行了重矿物研究。结果表明,本区重矿物可划分为4个矿物组合区,即三角洲前缘南部矿物区(Ⅰ区)、三角洲前缘北部矿物区(Ⅱ区)、前三角洲主体矿物区(Ⅲ区)和前三角洲南部矿物区(Ⅳ区),它们代表了不同的沉积动力、沉积环境和风化作用条件;长江水下三角洲重矿物以普通角闪石-绿帘石为优势矿物组合,以低级变质来源的绢云母、白云母为特征矿物,局部富含普通辉石和氧化铁矿物;粉砂质砂和砂质粉砂中的重矿物组成比较稳定,基本可以代表长江物源。     

西北冰洋楚科奇海台P31孔晚第四纪的陆源沉积物记录及其古海洋与古气候意义

通过对北冰洋西部楚科奇海台P31孔沉积物进行岩性特征和颜色旋回分析、XRF元素扫描、AMS14 C测年、有孔虫丰度统计、筏冰碎屑(IRD)(250和154μm)含量分析以及粒度组成的综合研究,建立了该孔的地层年代框架,其沉积物被划分为MIS 3-MIS 1的沉积序列。自MIS 3以来,楚科奇海台P31孔可以识别出5个IRD事件,它们分别出现在晚MIS 1、MIS 2和早中MIS 3期。这些IRD主要被来自加拿大北极群岛的冰山或者大块冰所携带,随波弗特环流搬运至楚科奇海台并卸载到海底,这不仅反映了晚第四纪冰期-间冰期旋回中北美冰盖的崩塌事件,还反映了波弗特环流的变化历史。粒度组分变化表明,细砂级组分主要来自于冰山或大冰块的搬运,因为其高值对应于IRD的高值,粉砂级组分可能主要来自于海冰的搬运,而黏土级组分主要由波弗特环流和雾状层所搬运。两个敏感组分(5～13和110～176μm)含量的变化呈现明显对称性分布,后者的变化对应于IRD的变化,前者可能指示了物源和沉积作用后期的影响。该孔MIS3-MIS1的沉积速率分别为2.2、0.16和1.6cm/ka,平均沉积速率约为1.2cm/ka。与北冰洋其他海区沉积速率资料对比显示,海冰边缘地区沉积速率较高,而永久性海冰覆盖区沉积速率低较。水深越浅,越靠近陆架物源区,沉积速率越高,纬度越高的门捷列夫-阿尔法脊和加拿大海盆区,沉积速率越低。