末次冰消期以来白令海盆的冰筏碎屑事件与古海洋学演变记录

通过对白令海盆中部BR02岩芯高分辨率的颜色、粒度和元素地球化学地层的研究发现:(1)该岩芯较为完整地记录了末次盛冰期结束以来(约16.3 ka BP)的多期冰筏碎屑事件,包括H1、OD、YD和北方2期,其中以H1和YD最为显著,反映了末次冰消期以来该地区海冰/冰山以及区域性冰川的消长变化;(2)BR02岩芯上部17—25 cm段出现富Mn、富Ba的氧化型沉积,说明在全新世高海面时期,白令海与北太平洋、北冰洋之间的水体交换达到极点,白令海环流加强,海盆底层水含氧状况明显改善,并引发海洋生产力增加;(3)CaO、Na2O、Sr、Zr及Na2O/K2O比值的分布说明,海盆冰筏碎屑主要来自富碳酸盐的育空河流域,其次为阿拉斯加半岛和阿留申群岛等火山岩区;岩芯上部Na2O/K2O比值的递增暗示10 ka BP以来与火山物质输运有关的北太平洋入流(阿拉斯加流)可能增加。     

南极鲍威尔海盆D4-9柱样古地磁及磁组构特征

为了探讨中更新世以来南极半岛东北部鲍威尔海盆沉积环境气候演变及古流向特征,对采自南极半岛东北部鲍威尔海盆内一根3m长柱样进行了古地磁和磁组构参数测试和特征分析。结果表明：1）该柱样在2.73m处为布容正极性与松山反极性期的界线,由此推算出在距今780ka到现代该区域沉积速率较低,约为0.35cm/ka。2）中更新世以来该区域共出现过5次暖沉积事件,并且在暖期事件中存在3次明显的冷期气候波动事件。3）该区域在暖期古流向方向不明显,水流方向变化频繁,而在暖期之间的过渡时期,古流向以近似南北向为主。     

南海西北次海盆地壳结构：海底广角地震实验结果

利用完整穿越南海西北次海盆及其两侧大陆边缘的海底广角反射/折射地震测线,反演了该地区的地壳结构.该测线总长484km,共投放海底地震仪（OBS）14台,台站间距30km,组合枪阵激发总容量5160in3（1in3=16.3871cm3）.结合同测线多道地震资料,通过OBS数据的精细处理和初始建模,利用射线追踪正反演技术,获得了西北次海盆地壳速度结构模型.结果表明,地壳厚度从上陆坡的21km减薄至下陆坡的14km,在西北次海盆为7.7km;莫霍面埋深从上陆坡的21km上升到海盆中央的11km.西北次海盆和东部次海盆的地壳速度结构相似,都为大洋地壳,但不同的是层1（沉积层）增厚,层2减薄,该特点在东部次海盆尤其明显.西北次海盆及其两侧边缘构造形态和速度结构对称分布,存在共轭关系,其陆缘张裂机制属纯剪切模式.模型中的西北次海盆北侧陆缘下地壳没有发现高速层,这为南海北部陆缘西部非火山型地壳性质提供了新的证据.西北次海盆海底扩张规模小、时间短,且层2可能经历了玄武岩岩浆的不对称溢流,这可能导致西北次海盆磁条带异常的模糊化.     

南海西南次海盆北缘海底地震仪测线深部地壳结构研究

基于2009年和2011年采集的海底地震仪数据,辅以多道地震数据,对南海西南次海盆北缘的地壳结构进行了探索.利用二维射线追踪的反演方法建立测线上的模型.利用声学基底面的反射波,下地壳顶界面的反射波和莫霍面的反射波走时的反演勾绘了地层中的不连续界面,利用自声学基底面下的折射波和来自上地幔的首波来反演整条测线的P波速度结构...     

Composition of fish species in the Bering and Chukchi Seas and their responses to changes in the ecological environment

Based on trawl surveys in the Bering Sea and Chukchi Sea during the 2010 Chinese National Arctic Research Expedition, fish biodiversity characteristics, such as fish composition, dominant species, biodiversity, and faunal characteristics were conducted. We also discussed the responses of fishes to the quick changes in Arctic climate. The results showed that a total of 41 species in 14 families were recorded in these waters. The dominant species were Hippoglossoides robustus, Boreogadus saida, Myoxocephalus scorpius, Lumpenus fabricii, and Artediellus scaber. There were 35 coldwater species, accounting for 85.37%, and six cold temperate species, occupying 14.63%. The habitat types of fish could be grouped as follows: 35 species of demersal fishes, five benthopelagic fishes, and one pelagic fish. The Shannon–Wiener diversity index(H)(range between 0 and 2.18, 1.21 on average) was not high, and descended from south to north. Climate change has caused some fishes to shift along their latitudinal and longitudinal distribution around the Arctic and Subarctic areas, and this could lead to the decline of Arctic fishery resources.     

初至波层析成像的反演参数选取:以南海中央次海盆三维地震探测数据为例

FAST(first arrival seismic tomography)软件是获取复杂地区三维深部结构的最常用工具之一,而反演参数选取是快速有效地获得真实合理的地震结构的关键环节。以南海中央次海盆三维地震探测数据为基础,采用先固定其中一个参数、选取另外一个参数、再综合选取的控制变量法,详细地介绍了FAST反演参数组合的选取过程。选取结果表明,反演参数组合(阻尼因子λ=2,平滑度权重因子sz=1,反演次数I=4)为南海中央次海盆三维地震结构的最佳反演参数,由此获得的最佳初步速度模型表明中央次海盆具有典型慢速扩张的洋壳结构。此项反演参数选取工作不仅为珍贝-黄岩海山链精细三维地震结构的正式模拟奠定了基础,同时为FAST软件在其他地区的应用提供了丰富的经验与借鉴。     

Mineralogical study of surface sediments in the western Arctic Ocean and their implications for material sources

Mineralogical analysis was performed on bulk sediments of 79 surface samples using X-ray diffraction. The analytical results, combined with data on ocean currents and the regional geological background, were used to investigate the mineral sources. Mineral assemblages in sediments and their distribution in the study area indicate that the material sources are complex. （1） Feldspar is abundant in the sediments of the middle Chukchi Sea near the Bering Strait, originating from sediments in the Anadyr River carried by the Anadyr Current. Sediments deposited on the western side of the Chukchi Sea are rich in feldspar. Compared with other areas, sediments in this region are rich in hornblende transported from volcanic and sedimentary rocks in Siberia by the Anadyr Stream and the Siberian Coastal Current. Sediments in the eastern Chukchi Sea are rich in quartz sourced from sediments of the Yukon and Kuskokwim rivers carried by the Alaska Coastal Current. Sediments in the northern Chukchi Sea are rich in quartz and carbonates from the Mackenzie River sediments. （2） Sediments of the southern and central Canada Basin contain little calcite and dolomite, mainly due to the small impact of the Beaufort Gyre carrying carbonates from the Canadian Arctic Islands. Compared with other areas, the mica content in the region is high, implying that the Laptev Sea is the main sediment source for the southern and central Canada Basin. In the other deep sea areas, calcite and dolomite levels are high caused by the input of large amounts of sediment carried by the Beaufort Gyre from the Canadian Arctic Islands （Banks and Victoria）. The Siberian Laptev Sea also provides small amounts of sediment for this region. Furthermore, the Atlantic mid-water contributes some fine-grained material to the entire deep western Arctic Ocean.     

氚输入函数的构造与北太平洋氚分布的模拟

使用一个开边界的北太平洋环流模式研究氚在北太平洋中的分布和输送. 首先, 选用全球同位素降水资料GNIP/ISOHIS, 用插值的方法构造模式区域1951~1997年的氚强迫函数. 之后将构造的氚强迫函数加为海表通量边界条件, 从零初始的氚分布积分环流模式47年. 将模拟结果与GEOSECS和WOCE的观测资料进行对比分析, 结果表明: 模式得到了与观测资料相符的经向梯度和次表层高值信号; 模拟出了北太平洋区域氚的总通量在1963年出现了明显的峰值, 氚的总储量在1975年后变化缓慢; 模式模拟的氚由高纬度海表进入, 经次表层输送向赤道方向转移, 与分析观测资料得出的结论是一致的. 但模拟结果在30°~40°N区域存在一定误差, 这种误差在模拟CFCs分布时也曾出现. 误差可能源于模式对这一区域物理过程描述的不足, 但在氚强迫函数构造过程中存在的不确定性因素也会影响模拟结果.     

南海西南海盆南缘中生代花岗闪长岩的发现及其构造意义

利用在南海西南海盆南缘首次发现的花岗闪长岩样品,通过等离子质谱仪、岩相显微镜和电子探针等设备对其地球化学组成进行了分析;并对其组分中黑云母矿物进行了40Ar/39Ar年代学研究。40Ar/39Ar等时线年龄显示岩石的结晶年龄为(109.5±1.5)Ma,是早白垩世岩浆入侵的产物。地球化学测试表明:样品以富SiO2、K2O,高Al2O3、贫TiO2为特征。地球化学-构造判别图解显示,样品属于火山弧花岗岩,为造山类花岗岩。样品可能是海盆早期张裂阶段裂谷系组成的重要岩石类型,而裂谷拉张的过程可能与现代红海的演化相似,经历了裂谷沉陷过程,当裂谷宽度、深度达到一定规模时,洋壳随之而产生。该样品的发现,揭示其产出位置可能是南海西南海盆的南部边界,而且是洋盆扩张初期断裂系统的组成部分,为探讨南海的张裂、形成与演化历史提供了新的线索。