末次盛冰期以来渤、黄、东海陆架底质分布演变过程模拟研究   总被引：1，自引：0，他引：1  

朱玉荣 《海洋科学进展》2002,20(1):11-24

渤、黄、东海陆架底质的形成分布与末次盛冰期之后的海侵密切相关。末次盛冰期结束、海侵开始以来 ,潮流是渤、黄、东海陆架上的永久性主导作用应力。为从长期沉积动力演变过程的角度 ,探讨渤、黄、东海陆架底质形成分布的有关成因问题 ,利用数值模拟手段 ,再现了末次盛冰期以来 6个时期渤、黄、东海陆架潮流作用下海底的冲淤格局及底质分布。结果表明 ,扬子浅滩南侧东海外陆架的砂质沉积基本上是自 - 80 m海面以来形成的。扬子浅滩形成于 -5 2 m海面之后 ,至 - 3 0 m海面时已有一定规模 ,全新世最大海侵之后 ,逐渐形成现在规模的扬子浅滩。南黄海中部泥自 - 5 2 m海面时就已开始形成 ,- 3 0 m海面时范围很大 ,侵入北黄海 ,全新世最大海侵以来 ,逐渐调整到现在的范围。渤海中央泥、北黄海西部泥、浙闽岸外泥、辽东半岛西侧与北侧的砂质沉积、西朝鲜湾与江华湾中的砂质沉积以及苏北浅滩是自全新世最大海侵以来逐渐形成的。海州湾中砂质沉积形成的盛期在公元 8世纪之后。济洲岛西南泥、南黄海东部泥很可能分别形成于 - 3 0 m海面、- 5 2 m海面以来。全新世渤、黄、东海陆架底质分布的演变过程大致分为 2个阶段 :全新世最大海侵之前为渤、黄、东海陆架底质分布宏观格局的形成阶段 ;全新世最大海侵至今为渤  相似文献   

Feeding ecology and abundance of two sympatric skates, the shortfin sand skate Psammobatis normani McEachran, and the smallthorn sand skate P. rudis Gunther (Chondrichthyes, Rajidae), in the southwest Atlantic   总被引：1，自引：0，他引：1  

Mabragana  Ezequiel; Giberto  Diego A. 《ICES Journal of Marine Science》2007,64(5):1017-1027

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Seasonal variations in faunal distribution and activity across the continental slope of the goban spur area (NE Atlantic)     

Els Flach  Carlo Heip 《Journal of Sea Research》1996,36(3-4)

Density, biomass and community structure of macrofauna were estimated together with several sediment characteristics at seven stations ranging from 208 m to 4460 m water depth along the OMEX transect in the Goban Spur area (NE Atlantic) during three seasons (October 1993, May 1994, and August 1995). Median grain size decreased with increasing water depth and showed no differences between the seasons. The percentages of organic carbon and total nitrogen were highest at mid-slope depths (1000 to 1500 m), and were significantly higher in August at the upper part of the slope to a depth of 1500 m. The C:N ratio in the surface layer amounted to 7 to 8 in May, 10 to 12 in August and 14 to 17 in October at all stations (except the deepest at 4460 m, where it was 11 in May and August), indicating arrival of fresh phytodetritus in May, and therefore seasonality in food input to the benthos. Densities of macrofauna decreased exponentially with increasing water depth. Significantly higher densities of macrofauna were found in May at the upper part of the slope to a depth of 1500 m. These differences were mainly due to high numbers of postlarvae of echinoids at the shallowest station and ophiuroids at the deeper stations. Biomass values also decreased with increasing water depth, but biomass was relatively high at the 1000 m station and low at 1500 m, due to relatively high and low mean weights of the individual macrofaunal specimens. No significant differences in biomass were found between the seasons. Respiration was high (15 to 20 mgC·m⁻²·d⁻¹) in May at the upper part of the slope to a depth of 1000 m and low (1–3 mg C·m⁻²·d⁻¹) at the deeper part. At the shallowest stations to a depth of 1000 m respiration was highest in May, at the mid-slope stations (1400–2200 m) it was highest in August, whereas the deepest stations (3600 to 4500 m) did not show any differences in respiration rates. In conclusion; seasonal variation in organic input is reflected in denstiy, community structure and activity of the macrofauna along the continental slope in the NE Atlantic.  相似文献   

东海陆架前缘斜坡北部的滑塌带   总被引：1，自引：0，他引：1  

李成钢  范奉鑫  阎军 《海洋科学》2007,31(5):90-92

从1994年对东海陆架前缘斜坡北部实测的8条浅地层记录中,我们发现这些测线上都有滑塌构造,并形成了一条平行于陆架转折线的滑塌带,滑塌带呈NNE向展布,平均宽约7.5km,它们是沉积物流从陆坡上部向下移动的证据。  相似文献   

夏季流经东沙群岛北侧的一支偏西向海流     

黄企洲  王文质  傅孙成  陈荣裕  李毓湘  周国荣 《热带海洋学报》1997,(2)

主要根据1992年8月中国科学院南海海洋研究所和香港理工大学合作进行的“南海环流试验”的调查资料，并引用中国科学院南海海洋研究所1982年7月、1985年8月在南海东北部的调查资料、黑潮合作调查（CSK）的资料，通过温、盐度分布特征的分析，并结合动力计算结果，指出夏季在南海东沙群岛北侧存在着一偏西向海流，它的流动路径与文献[5－7]中所说的南海黑潮分支的流动路径显著不同。对夏季南海海流的三维数值模拟也得到了相似的结果。  相似文献   

Southern Segment of the European Geotraverse — a wide-angle seismic refraction experiment in the Sardinia Channel     

C. Peirce  P. J. Barton 《Marine Geophysical Researches》1992,14(3):227-248

The Sardinia Channel dataset was collected as part of the European Geotraverse (EGT)—a 4000 km seismic refraction line running from Northern Norway to the Sahara, designed to investigate the structure of the lithosphere beneath Europe. Wideangle seismic data recorded by ocean bottom seismometers deployed in the Sardinia Channel as part of the Southern Segment of the EGT, together with gravity data, were used to constrain the final crustal model. In the centre of the Channel the crust is identified as thinned continental in nature, with a crystalline thickness of 10 km overlain by 4 km of sediments and 2.5 km of water in the most extended region. High velocities in the lower crust in the central region are thought to represent an area of underplating or intrusion by igneous material caused by extension related to the opening of the Tyrrhenian Sea. The crust overlies an anomalously low velocity upper mantle.  相似文献   

造山带大陆斜坡沉积类型     

蔡雄飞  蔡海磊  刘德民  陈斌 《海洋地质前沿》2006,22(1):9-13

造山带大陆斜坡可以划分出有扇与无扇大陆斜坡两种沉积类型。有扇大陆斜坡以近源浊积岩、碎屑流为特色;无扇大陆斜坡以远源浊积岩、等深岩、半远洋沉积为特色。因而大陆斜坡也是一个多种沉积作用活跃的场所。造山带深水沉积绝不是常人认为是单一的复理石、千篇一律的重力流,而是内容十分丰富的沉积作用非常活跃和堆积的场所。  相似文献   

东海海底地形分区特征和成因研究   总被引：20，自引：0，他引：20  

刘忠臣  陈义兰  丁继胜  张卫红  吴永亭  郭发滨 《海洋科学进展》2003,21(2):160-173

东海一直以其特殊的大地构造地位受到国内外地学界的关注,但作为主要受构造控制的东海海底地形的研究,以往简单趋势性描述居多,专门深入系统的研究尚不多见。不久前完成的高精度、全覆盖多波束海底地形勘测覆盖了东海部分外陆架、大陆坡全部、冲绳海槽和东部岛坡的一部分,取得了海量的测深数据。据此编绘的勘测多波束水深图和结合测区外的传统资料编绘的海底地形图使我们有机会可以重新审视和系统研究东海的海底地形特征。在定量确定了陆架坡折线、陆坡坡脚线和东部槽坡坡脚线的基础上划分出了大陆架、大陆坡、冲绳海槽平原和东部岛坡4大地形区,继之对各区的海底地形特征进行了研究和描述,并在区内选取了有代表性的5条剖面进行了剖析。另外,从地球内营力和外营力两方面分析了影响东海海底地形发育的因素。调查分析表明:整个东海地形分带明显,地形类型多样:大陆架十分宽阔,总体北宽南窄,从大陆向海平缓倾斜,发育了广泛的NW-SE向沙脊群,自大陆向东南呈扇形发散;大陆坡呈NE-SW向条带展布,海底地形陡峻,呈阶梯状下掉,总体北缓南陡,其上峡谷密布,上穿切外陆架,下直达海槽,同时坡麓上海台沟谷伴生发育;冲绳海槽北浅南深,其内在平坦的背景上发育了众多的海山和海丘,其中心又有槽中槽地形;东槽坡地形复杂,发育了  相似文献   

中国大陆岩石圈等效粘滞系数的计算和讨论   总被引：27，自引：0，他引：27  

石耀霖  曹建玲 《地学前缘》2008,15(3):82-95

大陆岩石圈的流变结构对岩石圈动力学过程有很大的影响,因此对岩石圈等效粘度的估计是大陆动力学研究中基础和重要的问题。文中对利用实验室流变实验结果估算岩石圈流变结构的计算方法中包含的多种不确定性进行了讨论,包括岩性、温度、应变速率、实验室速率数据外推到地质构造运动速率等因素对等效粘滞系数估算的影响,并以温度和应变速率的新研究成果为基础,对中国大陆地壳和上地幔等效粘滞系数做出了估计。中国中地壳等效粘滞系数一般在1021~1024Pa.s,下地壳等效粘滞系数在1021~1022Pa.s,其中青藏高原下地壳等效粘滞系数较低,约为1019~1020Pa.s;与前人研究认为青藏高原存在柔性下地壳流动的结论吻合。  相似文献   

青藏高原北部新生代陆相盆地石油地质条件及勘探前景          下载免费PDF全文

孙瑕  伊海生  林金辉  周恳恳  李军鹏  黄华谷 《沉积与特提斯地质》2008,28(4):7-13

青藏高原北部陆相盆地中烃源岩发育层位包括始新统风火山组、渐新统雅西措组和中新统五道梁组。古近系雅西措组烃源岩,特别是灰岩属于中好烃源岩范畴,有机质类型较好,且烃源岩主体处于成熟阶段,是藏北高原新生代陆相盆地主力烃源岩的发育层位。陆相盆地储集岩较发育,储层较丰富,发育层位包括风火山组和雅西措组,其中雅西措组是储层主力分布层位。对测区分析数据表明：通天河盆地具备一定规模的生油岩厚度,而且有机质丰度为沱沱河地区最高,表明其勘探前景较好。  相似文献