末次盛冰期以来东海陆架南部EA05岩心地层划分及其古环境意义

通过综合分析东海陆架南部EA05岩心上部30 m的岩性、有孔虫丰度和一些特征的地球化学参数,探讨了该段岩心的气候地层划分。该段岩心可依次划分为末次盛冰期(30~11.85 m)、冰消期(11.85~5 m)和冰后期(5~0 m)地层。末次盛冰期时气温低,研究区水深浅,沉积物中有孔虫丰度很低,且大多数热带浮游有孔虫种属消失,此时陆源物质输入量较大,沉积物中有机质含量高,黑潮对东海陆架南部影响小。随着冰消期以来气温回升,海面上升,研究区水深增大,岩心中有孔虫丰度急剧增加;陆源物质输入量减少,沉积速率降低。大约在16 ka B.P.左右,黑潮重新开始对东海南部陆架产生影响。在EA05岩心的6~5 m,3.4~3.0 m和1.4~1.2 m处分辨出了3个冷事件,可能分别对应于YD事件、8.2 ka B.P.冷事件和3.8 ka B.P.新冰期Ⅲ,反映出该地区冰消期和冰后期气候波动较大。     

Input of river-derived sediment to the New Zealand continental shelf: I. Mass

The input of river-borne sediments to the New Zealand continental shelf has been calculated for all the major rivers and basins in New Zealand. South Island yields 284 ± 40 × 10⁶ tonnes per year of sediment from a land area of 152 977 km² and North Island yields 105 ± 9·4 × 10⁶ tonnes per year from a land area of 114 621 km². Particularly high discharges are noted off the west coast of South Island and east coast of North Island and result in higher offshore sedimentation there. The data are compatible with measured sedimentation rates on the New Zealand continental shelf. The specific sediment yield from South Island is amongst the highest previously recorded.     

冲绳海槽--弧后背景下大陆张裂的最高阶段

高热流、强地震活动、火山活动、张性断层作用以及快速沉降等特征表明部绳海槽的演化已经达到了大陆张裂的最高阶段。根据地震折射和重力资料的计算表明冲绳海槽底下存在低密度的异常地幔，冲绳海槽的莫霍面介于15．4－23．8km之间。在我们提出的边缘海盆地演化旋回中，冲绳海槽处于胚胎期，即处在大陆张裂的最高阶段和弧后海底扩张的过滤阶段。冲绳海槽也可视为是威尔逊旋回中连接东非裂谷和红海阶段的一个重要的中间环节。     

大洋和大陆边缘岩石圈有效弹性厚度的研究意义

大洋岩石圈有效弹性厚度分布在 (45 0± 15 0 )℃等温面内 ,并且随着加载时岩石圈年龄的增加而增加。因此 ,大洋岩石圈的挠曲刚度强烈地依赖岩石圈的热结构。一些海隆下岩石圈有效弹性厚度的降低 ,可能是岩石圈经历过热活化 ,岩石圈热年龄降低的结果。大西洋一些群岛的岩石圈有效弹性厚度小于理论值 ,则反映了岩石圈结构的不同。在海沟 ,板块的挠曲也是影响岩石圈有效弹性厚度的因素 ,它降低了岩石圈的强度。在被动大陆边缘海陆岩石圈交界处 ,向陆的方向 ,岩石圈弹性厚度比同年龄的大陆或大洋岩石圈的小 ,表明强度明显降低 ;向大洋方向 ,岩石圈的弹性厚度与正常的大洋岩石圈弹性厚度吻合。在活动大陆边缘的挠曲前陆盆地和造山带 ,岩石圈有效弹性厚度变化较大 ,部分地区受先前的岩石圈低强度影响 ,而表现出岩石圈强度的弱化。同时 ,这种方法还广泛地用于大洋中脊岩浆侵位、地幔流动、南太平洋超级海隆的动力学机制、大陆边缘的变形和构造演化、新生岩石圈的力学性质和流变学性质的研究     

板块三节点

三条板块边界常相交于一点，这一个交点就叫做板块三联接合点(简称三联点，或称三节点)。三联点相接的3个板块之间的边界可以是拉张型、挤压型或剪切型的边界，它们的组合类型比较复杂，而且稳定性不同，这对精细研究海底构造格局与演化具有重要的意义。三节点的稳定性取决于相邻板块运动的方向，一个空间位置稳定的三节点不一定在演化期间其构造活动性是稳定的或空间位置永远不变，一个不稳定的三节点必然发展到稳定的三节点。文中系统分析了海沟、洋脊以及转换断层的16种组合的几何学和相关三节点的稳定性。     

The Ionian Abyssal Plain (central Mediterranean Sea): Morphology, subbottom structures and geodynamic history – an inventory

In order to understand the structure and evolution of the Mediterranean Ridge accretionary complex, it is necessary to understand the structure and history of its foreland. The Ionian Abyssal Plain is one of the varying types of foreland. The state of knowledge for that is presented. Its contour and detailed relief are described for the first time. Based on published and hitherto unpublished seismic data, information on the thickness of the Plio-Quaternary and on the Messinian evaporites are presented. Of particular interest are data concerning the pre-Messinian reflectors. They indicate a pattern of tilted blocks and horst-like features created in pre-Messinian time by tensional tectonics. Varying subsidence continued, however, during Messinian time and controlled the thickness of evaporites. At some places (e.g. Victor Hensen Seahill) vertical tectonics seem to be still active. The main tectonic structures of the Ionian Abyssal Plain are not related to the process of the present accretion and subduction at the Africa/Eurasia plate boundary but are pre-existing and should influence the internal structure of the Mediterranean Ridge which is still growing at the expense of the foreland. As a consequence of our structural evidence, we favour the following interpretation: the Ionian Abyssal Plain is not a remainder of the Jurassic Tethyan ocean but originated by extensive attenuation of continental crust.     

大陆构造样式及大陆动力学模式初探

根据大陆构造的最新研究成果,总结了大陆构造的基本型式,提出了大陆五层两域的构造模型,并从物质流变和构造变形的有机联系出发,探讨了大陆动力学的层流隆陷机制。     

苏北浅滩成因的最新研究

本文指出苏北浅滩在全新世海侵发生前,有可能为独立的“沙漠堆积体”,而不是所谓古长江—古黄河三角洲沉积。晚更新世末期,冰期气候使蒙古高压增强,在风蚀出露的陆架上产生了沉积分异作用,较粗的物质在“苏北浅滩”附近集中,形成沙丘群;较细的物质被搬运至扬州—南京一带,形成了黄土沉积。来自黄河、长江等河流带来的陆源物质,随沿岸流的搬运而将过去的沙漠堆积复盖。所以“苏北浅滩在全新世海侵前是古风暴活动区;而海侵后又为风暴潮活动区,全新世海侵发生以后,陆架沙漠化作用终止。     

Benthic microalgal biomass in sediments of Onslow Bay, North Carolina

Sediment samples were collected at stations along cross-shelf transects in Onslow Bay, North Carolina, during two cruises in 1984 and 1985. Station depths ranged from 11 to 285 m. Sediment chlorophyll a concentrations ranged from 0·06 to 1·87 μg g⁻¹ sediment (mean, 0·55), or 2·6–62·0 mg m². Areal sediment chlorophyll a exceeded water column chlorophyll a a at 16 of 17 stations, especially at inshore and mid-shelf stations. Sediment ATP concentrations ranged from 0 to 0·67 μg g⁻¹ sediment (mean, 0·28). Values for both biomass indicators were lowest in the depth range including the shelf break (50–99 m). Organic carbon contents of the sediments were uniformly low across the shelf, averaging 0·159% by weight. Photography of the sediments revealed extensive patches of microalgae on the sediment surface.Our data suggest that viable benthic microalgae occur across the North Carolina continental shelf. The distribution of benthic macroflora on the North Carolina shelf indicates that sufficient light and nutrients are available to support primary production out to the shelf break. Frequent storm-induced perturbations do not favour settling of phytoplankton, an alternative explanation for the presence of microalgal pigments in the sediments. Therefore, we propose that a distinct, productive benthic microflora exists across the North Carolina continental shelf.     

珠江口盆地的构造特征与盆地演化

断裂和断块构造是南海北部陆缘新生代构造作用的基本特征。通过断裂，断块以及其他地持的分析，认为珠江口盆地属过陆缘张裂盆地，并初步建立该盆地的构造演化模式。