Constraining the origin and evolution of confined turbidite systems: southern Cretan margin,Eastern Mediterranean Sea (34°30–36°N)

Bathymetric, 9.5-kHz long-range sidescan sonar (OKEAN), seismic reflection and sediment-core data are used in the analysis of two tectonic troughs south of Crete, Eastern Mediterranean Sea. Here, up to 1.2 s two-way travel time (TWTT) of strata have accumulated since the Middle Miocene in association with extension in the South Aegean region. The study area comprises >100-km- long by >25-km-wide basins filled by sediments subdivided into two seismic units: (1) an upper Unit 1 deposited in sub-basins which follow the present-day configuration of the southern Cretan margin; (2) a basal Unit 2, more than 500 ms (TWTT) thick, accumulated in deeper half-graben/grabens distinct from the present-day depocentres. Both units overlap a locally stratified Unit 3 comprising the pre-Neogene core complex of Crete and Gavdos. In this work, the interpreted seismic units are correlated with the onshore stratigraphy, demonstrating that denudation processes occurring on Crete and Gavdos in response to major tectonic events have been responsible for high sedimentation rates along the proximal southern Cretan margin. Consequently, topographically confined sedimentary units have been deposited south of Crete in the last 12 Ma, including turbidites and other mass-flow deposits fed by evolving transverse and axial channel systems. Surface processes controlling facies distribution include the direct inflow of sediment from alluvial-fan systems and incising mountain rivers onto the Cretan slope, where significant sediment instability processes occur at present. In this setting, seismic profiles reveal eight different types of stratigraphic contacts on basin-margin highs, and basinal areas show evidence of halokinesis and/or fluid escape. The acquired data also show that significant changes to the margin’s configuration occurred in association with the post-Alpine tectonic and eustatic episodes affecting the Eastern Mediterranean.     

用铀系定年法测定南永1井珊瑚礁年龄

运用铀系定年法首次对南水1井珊瑚礁岩心中的两个层位进行测年,结果与~(14)C测年一致,证实在晚更新世与全新世之间存在沉积间断面。     

福建罗源湾海滩互花米草盐沼中18种金属元素的分布

本文对福建罗源湾可湖海滩互花米草盐沼中的18种金属进行了测试,结果表明,罗源湾可湖海滩的环境质量基本是好的,并探讨了开发利用互花米草的新途径。     

一种树型网络拓扑简图的生成算法

给出一种树型网络拓扑的语义描述方法及其拓扑简图的生成算法。该方法通过建立网络联接线路标识串集和网络设备连接标识串集，来构造网络设备的拓扑描述，并计算生成网络拓扑简图。     

Mechanisms controlling the temporal variation of the sea ice edge in the Southern Ocean

This paper examines the mechanism controlling the short time-scale variation of sea ice cover over the Southern Ocean. Sea ice concentration and ice velocity datasets derived from images of the Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave Imager (SSM/I) are employed to reveal this mechanism. The contribution of both dynamic and thermodynamic processes to the change in ice edge location is examined by comparing the meridional velocity of ice edge displacement and sea ice drift. In the winter expansion phase, the thermodynamic process of new ice production off the ice edge plays an important role in daily advances of ice cover, whereas daily retreats are mostly due to southward ice drift. On the other hand, both advance and retreat of ice edges in the spring contraction phase are mostly caused by the dynamic process of the ice drift. Based on the above mechanism and the linear relation between the degree of ice production at the ice edge and northward wind speed, the seasonal advance of ice cover can be roughly reproduced using the meridional velocity of ice drift at the ice edge.     

The Levant Slumps and the Phoenician Structures: collapse features along the continental margin of the southeastern Mediterranean Sea

Two distinct series of slumps deform the upper part of the sedimentary sequence along the continental margin of the Levant. One series is found along the base of the continental slope, where it overlies the disrupted eastern edge of the Messinian evaporites. The second series of slumps transects the continental margin from the shelf break to the Levant Basin. It seemed that the two series were triggered by two unrelated, though contemporaneous, processes. The shore-parallel slumps were initiated by basinwards flow of the Messinian salt, that carried along the overlying Plio-Quaternary sediments. Seawater that percolated along the detachment faults dissolved the underlying salt to form distinctly disrupted structures. The slope-normal slumps are located on top of large canyons that cut into the pre-Messinian sedimentary rocks. A layer of salt is found in the canyons, and the Plio-Quaternary sediments were deposited on that layer. The slumps are bounded by large, NW-trending faults where post-Messinian faulted offset was measured. We presume that the flow of the salt in the canyons also drives the slope-normal slumps. Thus thin-skinned halokynetic processes generated the composite post-Tortonian structural patterns of the Levant margin. The Phoenician Structures are a prime example of the collapse of a distal continental margin due to the dissolution of a massive salt layer.     

海带雌性原生质体的分离与培养

于1993年1月 - 1993年4月，为了制备遗传性纯一的基因工程受体，用酶法从海带雌配子体单性生殖系分离雌性单倍体原生质体。从皱纹盘鲍消化腺及消化器官提取出鲍酶，在25°C下、1％（W／V）的鲍酶与2％（W／V）的纤维素酶（Onozuka R－10）合用能有效解离单细胞和原生质体。海带雌性原生质体经2d培养再生了细胞壁。     

黄河入海泥沙对渤海和黄海沉积作用的影响

渤海平均水深18m，最大水深70m，是一个较浅的海湾。黄海平均水深38m，其中部为水深大于50m的盆地。它们的共同特征是陆地环绕。沿岸河流输沙特征对沉积作用过程有重大影响，特别是黄河入海泥沙的影响尤为显著。 关于黄河人海泥沙对渤海和黄海沉积作用的影响，前人已从不同角度进行过讨论。黄河是世界上著名的多沙性河流。由于黄河尾闾长期以来不断发生变迁，纵横摆动于华北平原之上，交替注入渤海和黄海，因此，在讨论黄河入海泥沙在中国近海沉积中的作用时，必须把渤海和黄海作为一个整体，甚至南涉东海。本文试图在以往工作的基础上，概括讨论黄河入海泥沙对渤海和黄海海底沉积作用的影响。     

锯缘青蟹NAGase的催化机理的判断

以p-硝基苯酚-β-D-氨基葡萄糖苷（pNP-NAG）为底物，研究产物类似物：p-羧基苯酚和苯酚对青蟹N-乙酰-β-D-氨基葡萄糖苷酶（NAGase，Ec3．2．1．52）活力的影响．结果表明：p-羧基苯酚和苯酚对该酶有抑制的作用，IC50分别为20．0和100．0mmol／dm^3．p-羧基苯酚和苯酚对酶的抑制均表现为竞争性类型，其抑制常数K1分别为5．03和25．67mmol／dm^3．结合产物N-乙酰-β-D-氨基葡萄糖（NAG）抑制作用表现为反竞争性类型，判断NAGase水解pNP-NAG反应为有序双双反应（Ordered Bi Bi）．