关于Mckenzie沉积盆地初始沉降公式的修正     

毕传学  王良书 《海洋学研究》1993,11(2):9-12

根据Airy均衡原理对Mckenzie沉积盆地初始沉降公式进行了修正,并导出了公式的正确表达式 S=(a[(ρ_o-ρ_c)t_c/a(1-(aT_1t_c)/(2a))-(aT_1ρ_o)/2](1-1/β))/(ρ_o(1-aT_1)-ρ_w)  相似文献   

Rifting to Spreading Process along the Northern Continental Margin of the South China Sea   总被引：7，自引：0，他引：7  

Kido  Yukari  Suyehiro  Kiyoshi  Kinoshita  Hajimu 《Marine Geophysical Researches》2001,22(1):1-15

Understanding the development from syn-rift to spreading in the South China Sea (SCS) is important in elucidating the western Pacific's tectonic evolution because the SCS is a major tectonic constituent of the many marginal seas in the region. This paper describes research examining the transition from rifting to spreading along the northern margin of the SCS, made possible by the amalgamation of newly acquired and existing geophysical data. The northernmost SCS was surveyed as part of a joint Japan-China cooperative project (JCCP) in two phases in 1993 and 1994. The purpose of the investigation was to reveal seismic and magnetic characteristics of the transitional zone between continental crust and the abyssal basin. Compilation of marine gravity and geomagnetic data of the South China Sea clarify structural characteristics of its rifted continental and convergent margins, both past and present. Total and three component magnetic data clearly indicate the magnetic lineations of the oceanic basin and the magnetic characteristics of its varied margins. The analyses of magnetic, gravity and seismic data and other geophysical and geological information from the SCS led up to the following results: (1) N-S direction seafloor spreading started from early Eocene. There were at least four separate evolutional stages. Directions and rates of the spreading are fluctuating and unstable and spreading continued from 32 to 17 Ma. (2) The apparent difference in the present tectonism of the eastern and western parts of Continent Ocean Boundary (COB) implies that in the east of the continental breakup is governed by a strike slip faulting. (3) The seismic high velocity layer in the lower crust seems to be underplated beneath the stretched continental crust. (4) Magnetic anomaly of the continental margin area seems to be rooted in the uppermost sediment and upper part of lower crust based on the tertiary volcanism. (5) Magnetic quiet zone (MQZ) anomaly in the continental margin area coincides with COB. (6) The non-magnetic or very weakly magnetized layer is probably responsible for MQZ. One of the causes of demagnetization of the layer is due to hydrothermal alteration while high temperature mantle materials being underplated. Another explanation is that horizontal sequences of basalt each with flip-flop magnetization polarity cancel out to the resultant magnetic field on the surface. We are currently developing a synthetic database system containing datasets of seismicity, potential field data, crustal and thermal structures, and other geophysical data to facilitate the study of past, contemporary and future changes in the deep sea environment around Japan; i.e. trench, trough, subduction zones, marginal basins and island arcs. Several special characteristics are an object-oriented approach to the collection and multi-faceted studies of global data from a variety of sources.  相似文献   

南黄海陆架沉积学研究   总被引：4，自引：0，他引：4  

申顺喜 《海洋科学》1993,17(5):24-28

黄海中部、济州岛西南,存在厚层的泥质沉积,它们分别与上述地区的冷涡活动区相对应。在两个泥质沉积区之间又出现连接它们的通道,形成别有特征的“冷涡-通道”沉积体系。经分析发现,这个沉积体系,完全受控于黄海暖流、冷涡及其相关的环流体系。此外,在黄海西南部及东海北部海底发现大面积砂岩及其砾石,揭示了黄、东海陆架沉积物的新源地。  相似文献   

Siltation Prediction for Navigation Channels and Harbour Basins on Muddy Beach   总被引：2，自引：0，他引：2  

Liu Jiaju Zhang Jingchao Prof. Senior Engineer  River  Harbour Department  Nanjing Hydraulic Research Institute  Nanjing Senior Engineer  River  Harbour Department  Nanjing Hydralulic Research Institute  Nanjing 《中国海洋工程》1992,(2)

- This paper, after briefly reviewing the experimental research on sediment transport on muddy beach since the 1950s, improves and perfects the method for forecasting siltation in navigation channels and harbour basins which was first put forward in China by the authors. In consideration of silty sediment and sand, some factors in forecasting methods have been changed and modified. Consequently, the modified methods can be used either to compute siltation in navigation channels and harbour basins on muddy beach or to compute siltation and scouring in navigation channels and harbour basins on both silty beach and sandy beach. The verification of field data from eleven large, medium and small natural harbours shows a good agreement between the forecasting by the modified method and the natural conditions. Finally, the paper deals with the rational utilization of water area after the construction of the West Dyke in Lianyungang, the maintenance of water depth of the navigation channel at the entrance, siltation distribution, siltation in the navigation channel and harbour basin for ships of 100 thousand tonnnage. Results once again prove that the prospect of constructing Lianyungang Harbour into a deepwater harbour is bright.  相似文献   

南海深海盆地沉积柱样中的浊流沉积     

陈峰  蔡锋 《台湾海峡》1992,11(4):339-344

本文根据南海深海盆地三个沉积柱样的粒度结构、地球化学、微体古生物等特征分析,深讨了南海深海盆地细粒沉积物的浊积现象。结果表明,位于南海北部陆架斜坡上KL37孔的浊流沉积现象并不明显;位于陆架斜坡和深海盆地交界处的KL29孔存在着大量的浊积层,属于浊流沉积和半远洋沉积环境;位于南海盆地中部的KL91孔虽然已属于远洋性沉积环境,但除出现火山灰沉积外,浊流沉积作用仍然是相当活跃的。  相似文献   

潮汐沉积率与沉积间断   总被引：16，自引：3，他引：16  

李从先  王平  范代读  李铁松 《海洋地质与第四纪地质》1999,19(2):11-18

在浙北奥陶系文昌组和长江三角洲开敞型淤泥质海岸非潮道潮汐纹层研究的基础上,得出与国外同类研究相近的沉积率。现代海岸进积速度和潮坪沉积的观察及测试证明,上述沉积率是难以置信的。现代潮坪观测表明,潮汐纹层在形成过程中即包含着改造,所保留的纹层占应形成数的不到１０％,其余９０％以上被侵蚀。小型层序是风暴和平静天气的产物,为风暴层序,与大小潮周期无关。其地层中保留的数量不到应生成数的１０％,其余９０％被改造。小型层序被侵蚀,其中的纹层随之消失。致使潮坪层序中保存的纹层数仅为应形成数的０．２％。被改造的纹层和单层留下的仅是侵蚀面,即小间断。在进行潮汐沉积高分辨率的研究时应充分重视沉积间断的作用  相似文献   

东海南海交接带重磁场特征及新生代盆地成因     

吴时国  郭军华  刘展 《海洋地质与第四纪地质》2004,24(3):49-55

东海南海构造交接带及其邻近海区(简称交接带)位于中国东部大陆边缘,东邻俯冲板块边界。台湾以北是琉球海沟俯冲带,台湾以南为马尼拉海沟俯冲构造带。区域重磁资料分析结果表明,该东海陆架区存在3条重力高和2条重力低,重力高分别对应于闽浙隆起带、渔山低凸起和陆架外缘隆起,最大值高达50×10-5m·s-2;重力低对应于沉积盆地,最低值在台西南盆地,约为-20×10-5m·s-2。重磁特征表明东海盆地外缘台湾 钓鱼岛构造带具有明显的自由空间异常,磁场为平缓负异常,由古近系、白垩系或更老的变质岩及中新世的侵入岩组成,向南延伸至澎湖隆起。因为澎湖隆起具有高重力异常,放射性年龄表明这些碱性玄武岩形成于17 8～8MaBP,其特征同现在的琉球岛弧一样,可能是残留的古琉球岛弧。台西南盆地南侧(上陆坡)的凸起具有类似的幅度异常,呈ENE—WSW向,并消失在台西南盆地南段。新生代以来,盆地张裂活动具有不同时性,并向陆架边缘变得年轻。东海大陆边缘盆地属弧后残留盆地成因,多因岛弧的迁移而新生,但珠江口盆地则是被动大陆边缘裂陷作用所致。  相似文献   

莺歌海盆地形成与演化的动力学机制   总被引：4，自引：0，他引：4  

孙向阳  任建业 《海洋地质与第四纪地质》2003,23(4):45-50

莺歌海盆地位于印支半岛与南海北部大陆边缘交接区,复杂的地质构造背景使其形成演化的动力学机制成为国内外的研究焦点。从区域动力学演化的角度,系统分析了影响莺歌海盆地发育的印支地块构造演化特征,认为莺歌海盆地构造演化主要受印支半岛早期的逃逸挤出构造和晚期的挤压-伸展构造系统影响(或控制),在此动力学驱动机制下,莺歌海盆地新生代以来的构造演化经历了3个阶段,即左旋走滑-伸展裂陷阶段、中下地壳韧性伸展-热沉降阶段和加速沉降阶段。  相似文献   

Sources and distribution of organic matter in a river-dominated estuary (Winyah Bay, SC, USA)   总被引：12，自引：0，他引：12  

Miguel A. Goi  Maria J. Teixeira  David W. Perkey 《Estuarine, Coastal and Shelf Science》2003,57(5-6):1023-1048

The sources and distribution of organic matter (OM) in surface waters and sediments from Winyah Bay (South Carolina, USA) were investigated using a variety of analytical techniques, including elemental, stable isotope and organic biomarker analyses. Several locations along the estuary salinity gradient were sampled during four different periods of contrasting river discharge and tidal range. The dissolved organic carbon (DOC) concentrations of surface waters ranged from 7 mg l⁻¹ in the lower bay stations closest to the ocean to 20 mg l⁻¹ in the river and upper bay samples. There was a general linear relationship between DOC concentrations and salinity in three of the four sampling periods. In contrast, particulate organic carbon (POC) concentrations were significantly lower (0.1–3 mg l⁻¹) and showed no relationship with salinity. The high molecular weight dissolved OM (HMW DOM) isolated from selected water samples collected along the bay displayed atomic carbon:nitrogen ratios ([C/N]a) and stable carbon isotopic compositions of organic carbon (δ¹³C_OC) that ranged from 10 to 30 and from −28 to −25‰, respectively. Combined, such compositions indicate that in most HMW DOM samples, the majority of the OM originates from terrigenous sources, with smaller contributions from riverine and estuarine phytoplankton. In contrast, the [C/N]a ratios of particulate OM (POM) samples varied significantly among the collection periods, ranging from low values of 5 to high values of >20. Overall, the trends in [C/N]a ratios indicated that algal sources of POM were most important during the early and late summer, whereas terrigenous sources dominated in the winter and early spring.In Winyah Bay bottom sediments, the concentrations of the mineral-associated OM were positively correlated with sediment surface area. The [C/N]a ratios and δ¹³C_OC compositions of the bulk sedimentary OM ranged from 5 to 45 and from −28 to −23‰, respectively. These compositions were consistent with predominant contributions of terrigenous sources and lesser (but significant) inputs of freshwater, estuarine and marine phytoplankton. The highest terrigenous contents were found in sediments from the river and upper bay sites, with smaller contributions to the lower parts of the estuary. The yields of lignin-derived CuO oxidation products from Winyah Bay sediments indicated that the terrigenous OM in these samples was composed of variable mixtures of relatively fresh vascular plant detritus and moderately altered soil OM. Based on the lignin phenol compositions, most of this material appeared to be derived from angiosperm and gymnosperm vascular plant sources similar to those found in the upland coastal forests in this region. A few samples displayed lignin compositions that suggested a more significant contribution from marsh C₃ grasses. However, there was no evidence of inputs of Spartina alterniflora (a C₄ grass) remains from the salt marshes that surround the lower sections of Winyah Bay.  相似文献   

珠江口和琼东南盆地天然气水合物形成和稳定分布的地球化学边界条件及其分布区   总被引：22，自引：0，他引：22  

陈多福  姚伯初  赵振华  徐文新 《海洋地质与第四纪地质》2001,21(4):73-78

通过对南海北部陆缘珠江口和琼东南盆地气田的天然气形成水合物的地球化学计算模拟及地质地球化学条件分析，对珠江口和琼东南盆地天然气形成水合物的地球化学边界条件及分布区进行了研究。认识到南海北部陆缘琼东南和珠江口盆地内的断裂构造是天然气向海底渗漏的通道，为天然气水合物在海底的形成提供了物源；盆地内巨厚的第四纪富有机质沉积也为天然气水合物形成提供了充足的细菌成因生物气源。在海底温度2－16℃范围内，琼东南盆地气田10种天然气和珠江口盆地气田18种天然气形成水合物的压力有比较大的范围，随温度增高，天然气水合物形成的压力增高；盆地间和各天然气样品之间形成水合物的压力均是不一致的。在南海海水平均盐度3．4％条件下，结合海底温度与水深变化资料，珠江口和琼东南盆地天然气水合物形成和稳定分布的海区是不同的，珠江口盆地小于230m水深的海区没有天然气水合物的形成，在230－760m水深的海区可能有天然气水合物的存在，天然气水合物的稳定分布区应该在大于860m水深的深水区；在琼东南盆地水深小于320m的海区不可能有天然气水合物的形成，在320－650m水深的海区可能有天然气水合物的存在，大于650m水深的海区是天然气水合物的稳定分布区。  相似文献