南海夏季风爆发日期和强度的短期气候预测方法研究

利用合成及相关统计方法，研究冬季南海季风指数与850hPa风场、500hPa高度、海表温度、OLR等环境场的相互关系及其影响南海夏季风活动的可能机制。指出冬季南海季风指数及环境场的异常特征可以作为预测南海夏季风活动的前兆信号。在此基础上建立了预测南海夏季风爆发日期和强度的概念模型，1998－2001年的预测试验取得了较好成绩。     

Geology and petroleum potential of the Fairway Basin in the Tasman Sea

The Fairway Basin is a large, generally north – south-trending, sediment-filled structure in water 1500 – 3000 m deep, on the eastern slope of the Lord Howe Rise in the Tasman Sea, and is partly within Australian jurisdiction. It was poorly known until a few years ago, when seismic profiling and piston coring cruises were carried out. The basin, about 1100 km long and 120 – 200 km wide, can be divided into three segments—north, central and south—that trend northwest, north and north-northwest, respectively. All three segments probably formed by thinning of continental crust during breakup of Lord Howe Rise and surrounding aseismic continental ridges in the Late Cretaceous and Paleocene. Normal faulting, large inputs of terrigenous sediment and subsidence to bathyal marine depths occurred during that time. A period of compression, perhaps related to overthrusting on New Caledonia, occurred in the Eocene, leading to uplift (and in parts, erosion) of northern Lord Howe Rise, and reversal of faulting in the basin. By the Oligocene, the area was again in bathyal depths, and pelagic ooze and some turbidites accumulated. The basinal sequence is generally 2000 – 4000 m thick, with 1200 – 3200 m of Cretaceous to Eocene sediment concentrated in depocentres, capped by 500 – 800 m of Oligocene and younger sediment. In the depocentres, numerous sedimentary diapirs pierce sedimentary sequences. The sedimentary diapirs appear to be fed by Cretaceous muds deposited during rifting. Often, these diapirs are overlain by faults extending to the seafloor, and hummocky bathymetry is possibly caused by fluid escape. The overall geology suggests that the Fairway Basin may be a large frontier hydrocarbon province. Seismic profiles display a bottom-simulating reflector above many depocentres, 500 – 700 m below the seafloor. The bottom-simulating reflector has positive polarity, which could result from a diagenetic phase transformation, a thin gas hydrate layer with a sharp top, or from the sharp base of a gas layer (probably beneath gas hydrates). Standard piston cores taken above diapirs and apparent fluid-escape features have recovered little gas. Other than drilling, the next steps in assessing petroleum potential are to clearly document fluid-escape structures, and to sample any fluids emitted for hydrocarbons.     

海相黏性土状态与直接快剪试验指标的经验关系

通过对大连海域第四系全新统海相黏性土385组试验数据的统计与分析,建立了第四系全新统海相黏性土(Q4m)液性指数IL与直接快剪试验指标-黏聚力Cq、内摩擦角q的经验关系,即Cq=10.623 I-1.8114L; q=-3.8289ln(IL)+5.8634。     

南黄海微体古生物研究概述

从20世纪50年代至今,我国的海洋微体古生物研究从无到有,并且得到迅速发展.其中有孔虫、介形虫、放射虫、超微化石等海洋微体生物壳体是海洋地质研究不可缺少和替代的重要部分.南黄海是我国开展微体古生物研究较早、研究基础较好的海区.本文旨在回顾过去,立足现代,展望未来.     

Distribution characteristics of delta reservoirs reshaped by bottom currents: A case study from the second member of the Yinggehai Formation in the DF1-1 gas field,Yinggehai Basin,South China Sea

The Dongfang1-1 gas field (DF1-1) in the Yinggehai Basin is currently the largest offshore self-developed gas field in China and is rich in oil and gas resources. The second member of the Pliocene Yinggehai Formation (YGHF) is the main gas-producing formation and is composed of various sedimentary types; however, a clear understanding of the sedimentary types and development patterns is lacking. Here, typical lithofacies, logging facies and seismic facies types and characteristics of the YGHF are identified based on high-precision 3D seismic data combined with drilling, logging, analysis and testing data. Based on 3D seismic interpretation and attribute analysis, the origin of high-amplitude reflections is clarified, and the main types and evolution characteristics of sedimentary facies are identified. Taking gas formation upper II (IIU) as an example, the plane distribution of the delta front and bottom current channel is determined; finally, a comprehensive sedimentary model of the YGHF second member is established. This second member is a shallowly buried “bright spot” gas reservoir with weak compaction. The velocity of sandstone is slightly lower than that of mudstone, and the reflection has medium amplitude when there is no gas. The velocity of sandstone decreases considerably after gas accumulation, resulting in an increase in the wave impedance difference and high-amplitude (bright spot) reflection between sandstone and mudstone; the range of high amplitudes is consistent with that of gas-bearing traps. The distribution of gas reservoirs is obviously controlled by dome-shaped diapir structural traps, and diapir faults are channels through which natural gas from underlying Miocene source rocks can enter traps. The study area is a delta front deposit developed on a shallow sea shelf. The lithologies of the reservoir are mainly composed of very fine sand and coarse silt, and a variety of sedimentary structural types reflect a shallow sea delta environment; upward thickening funnel type, strong toothed bell type and toothed funnel type logging facies are developed. In total, 4 stages of delta front sand bodies (corresponding to progradational reflection seismic facies) derived from the Red River and Blue River in Vietnam have developed in the second member of the YGHF; these sand bodies are dated to 1.5 Ma and correspond to four gas formations. During sedimentation, many bottom current channels (corresponding to channel fill seismic facies) formed, which interacted with the superposed progradational reflections. When the provenance supply was strong in the northwest, the area was dominated by a large set of delta front deposits. In the period of relative sea level rise, surface bottom currents parallel to the coastline were dominant, and undercutting erosion was obvious, forming multistage superimposed erosion troughs. Three large bottom current channels that developed in the late sedimentary period of gas formation IIU are the most typical.     

南海北部海区水团的判别分析

将判别分析应用于南海北部海区的水团分析。划分为八个水团:沿岸冲淡水团(F),近岸混合水团(M),暖表层水团(WS),表层水团(S),表—次层混合水团(SU),次层水团(U),次—中层混合水团(UI)和中层水团(I)。给出了各水团在四季代表月的Bayes多组判别的系数和参数。用资料检验判别的成效.冬季和春季可达95.90％以上,夏季为94.80％,秋季是全年最低值,为92.72％。讨论了造成错判的原因,并与Fisher判别作了比较。当测值维数较低时,建议选用Bayes判别。对八个水团以及各水团两两之间差异的显著性进行了检验,证实在每个季节中各水团之间的差异,都在高度置信水平(α=0.01)上具有显著性。因而,划分为八个水团是有实际意义的,其判别式的系数和参数,可用于实际的判别和预报。     

Geotechnical properties of evaporite soils of the Dead Sea area

The Dead Sea Basin is the lowest point on earth and is tectonically subsiding. During the Holocene Period the climate became much drier with increasing evaporation whereby initially lacustrine sediments were deposited from the non-marine brines, giving a multi-layered stratigraphy of lime carbonate and halite sediments. The lime carbonate sediments are comprised of laminated, clay to silt sized, clastic sediments (calcite) and authigenic aragonite and gypsum. The halite commonly appears as rock salt. Chemical industries, based on harvesting the salts from the Dead Sea, have developed on both the Israeli and the Jordanian sides of the basin. The lime carbonate soils are used for dike construction, and these soils, together with significant salt layers, are encountered in the foundations of structures, dikes, and tailings dams, requiring definition of their geotechnical properties. Use of standard soil mechanics definitions and testing approaches for the lime carbonates have been found inapplicable, particularly in view of their exceptionally high saline content, and it has been necessary to develop new concepts. The rock salt is encountered at shallow depths, with unit weights considerably lower than those usually discussed in the literature, and with correspondingly different mechanical properties. The geotechnical properties of these soils, and approaches used to define them, are discussed in the paper.     

末次冰消期以来东海内陆架古环境演化

通过对位于浙—闽沿岸泥质带的EC2005孔岩性、粒度以及AMS14C年代分析,探讨了研究区自末次冰消期以来的古沉积环境演化,认为是湖水或海水深度、气候变化等综合影响的结果。岩芯底部60.20～41.00 m（17.3～13.1 ka BP）为湖泊三角洲沉积序列,可划分为前三角洲—三角洲前缘—三角洲平原三个沉积亚相,物质来源主要是湖盆流域物质的输入。随着海平面的逐渐上升,海水自13.1 ka BP开始侵入研究区,形成了41.00 m的海相沉积地层,可划分为前滨—近滨—浅海三个沉积亚相,与海平面变化曲线具有良好的对应。自12.3 ka BP开始,研究区受到沿岸流影响,长江物质开始影响研究区,7.3 ka BP以来主要是来自长江的悬浮体在沿岸流作用下输送沉积而形成,稳定的泥质沉积物开始形成。全球性重要气候事件如新仙女木事件、8.2 ka冷事件在东海内陆架沉积物中也得到了良好揭示。     

南海北部台风海浪谱的双峰性和成长性

本论文通过对南海北部三次台风过境期间基于浮标观测的海浪谱进行分析,发现虽然大部分成熟的台风海浪谱为单峰结构,但实际上在台风海浪的成长和衰减阶段,双峰谱占据了很大的比例。双峰谱的形成主要是由于风浪和涌浪的叠加以及不同波分量之间的非线性相互作用,我们可以通过能量密度的成长率对谱型变化进行高效的预报。此外,台风海浪的主要波向依赖于台风中心相对观测点的位置,而波向的分散情况在相距台风中心较远的区域无明显规律。本文提出了一个新的六参数波浪谱型拟合双峰谱,其拟合效果相较于前人的谱型更好。通过验证,形状参数和谱宽度之间的理论关系依然适用于单个谱峰。通过分析谱参量的变化特征,证明了谱参量不仅与台风强度和台风路径相关,还存在很强的交互相关。最后通过拟合海浪谱数据,本文得到了台风影响下海浪有效波高和有效周期之间的成长关系,这对海洋工程实际应用具有重要意义。     

Holocene rockfalls in the southern Negev Desert,Israel and their relation to Dead Sea fault earthquakes

Rockfall ages in tectonically active regions provide information regarding frequency and magnitude of earthquakes. In the hyper-arid environment of the Dead Sea fault (DSF), southern Israel, rockfalls are most probably triggered by earthquakes. We dated rockfalls along the western margin of the DSF using terrestrial cosmogenic nuclides (TCN). At each rockfall site, samples were collected from simultaneously exposed conjugate boulders and cliff surfaces. Such conjugate samples initially had identical pre-fall (“inherited”) TCN concentrations. After boulder detachment, these surfaces were dosed by different production rates due to differences in post-fall shielding and geometry. However, in our study area, pre-rockfall inheritance and post-rockfall production rates of TCN cannot be evaluated. Therefore, we developed a numerical approach and demonstrated a way to overcome the above-mentioned problems. This approach can be applied in other settings where rockfalls cannot be dated by simple exposure dating. Results suggest rockfall ages between 3.6 ± 0.8 and 4.7 ± 0.7 ka. OSL ages of sediment accumulated behind the boulders range between 0.6 ± 0.1 and 3.4 ± 1.4 ka and support the TCN results. Our ages agree with dated earthquakes determined in paleoseismic studies along the entire length of the DSF and support the observation of intensive earthquake activity around 4–5 ka.