西沙群岛晚第四纪碳酸盐岩淡水成岩作用

基于西沙永兴岛上最新钻孔（SSZK1）取得的55.92 m岩芯的 U?Th定年、矿物、薄片、主微量元素及碳氧稳定同位素等资料,开展了西沙群岛晚第四纪碳酸盐岩沉积相和淡水成岩作用的研究。根据不同的矿物组成特征,可将SSZK1钻孔岩芯分为上、中、下三段: 下 段（33.89~55.92 m,主要为低镁方解石）、中 段（18.39~33.89 m,主要为文石和低镁方解石）、上段（0~18.39 m,主要为文石、高镁方解石和低镁方解石）。由于下段碳酸盐岩几乎全为稳定的低镁方解石组成,碳氧同位素值的严重负偏和小幅度变化,可推断其经历了程度较大的淡水成岩作用。中段和上段还存在不稳定的文石和高镁方解石,碳氧同位素值相对下段正偏和高幅高频变化,推测其淡水成岩作用的程度比下段要小。中段碳氧同位素值高幅高频变化同时也说明该段的矿物纵向变化较复杂。这种矿物组成的复杂变化可能是由于晚第四纪海平面频繁变化,该段被大气水渗流带和潜流带交替占据引起的。主微量元素的变化同时受到淡水成岩作用和沉积环境的影响。在中段、下段中可识别出sq1、sq2、sq3、sq4四个完整的相旋回。Na₂O,S,Sr 和碳氧同位素受到的淡水成岩作用而被消耗和负偏,且由于老一期的旋回经历了更长时间的淡水成岩作用,新、老旋回间的 Na₂O,S,Sr含量值和碳氧同位素值有明显差异。利用新、老时期形成的旋回间淡水成岩作用剩余Na₂O,S,Sr含量和碳氧同位素值的差别可以将新、老两个旋回区分开来。     

东亚大陆边缘的俯冲带构造

东亚大陆边缘自北向南发育了琉球海沟和马尼拉海沟等俯冲带。简要论述了这些俯冲带的构造特征、演化历史和一些科学前缘问题 ;认为愈来愈多的地球科学问题 ,如地震的发生机制、俯冲板块动力学等 ,集中在俯冲板块边界 ;解决弧后盆地成因和中国大陆边缘张裂过程等许多地质科学问题 ,有待于对俯冲带构造演化的深入了解。同时 ,在这些俯冲带发现了丰富的天然气水合物 ,具有良好的资源前景 ,因而 ,俯冲带的构造研究成为科学研究的前沿热点     

基于南黄海海相油气勘探的地震采集技术研究

南黄海盆地中部隆起区前第三系油气储层主要为中一古生代海相碳酸盐岩地层,厚度大、分布广,具有良好的油气前景.由于厚度小于1000 m的新近系低速地层直接覆盖在高速碳酸盐岩地层之上,对地震波的向下传播起到了强烈的屏蔽作用,使之深部目的层地震资料品质差,影响了油气勘探的进程.根据区域地质、地球物理特征,进行了基于AV0(Am...     

LATE QUATERNARY SEISMIC SEQUENCES AND SEDIMENTATION ALONG THE COAST OFF TAISHAN, GUANGDONG, AS REVEALED BY HIGH RESOLUTION SEISMIC DATA

Seismic stratigraphic analysis of 150 km of high-resolution seismic profiles (GEO-PULSE and 3.5 kHz) obtained along the muddy coast off Taishan, Guangdong provided valuable information on the offshore Quaternary stratigraphy, tectonics, sedimentary evolution, and environmental and engineering geology of this area. The following late Quaternary stratigraphic sequences were mapped. (1) Pleistocene alluvial silty sand and shallow marine clay; (2) coarse fluvial channel sand; (3) nearshore and bay clayey sediments. The incision of fluvial channels occurred in two stages: dttring the Late Pleistocene and at the beginning of the Holocene. The Pleistocene fluvial channels have been filled by coarses and overlain by more than 10 m of late Pleistocene clay and 20 - 30 m of Holocene clay. The coastal area is dissected by two major fault systems: the first group strikes ENE-WSW and controls the evolution of the adjacent Quaternary basin, while the second one trends NNE-SSW. These fault systems must be taken into account in any coastal engineering considerations. In addition, both granitic and metamorphic basements were recognized.     

Late Cenozoic Tectonic Deformation in the Dongsha Islands and Adjacent Sea Area

Dongsha Island and the adjacent sea area locate at the northern continental margin of the South China Sea (SCS), and is connected to the east by the Manila Trench. Analyses of seismic stratigraphy and gravity, magnetic and drilling wells data led to the discovery of three post-fault sequences (Ⅴ, Ⅵ, Ⅶ). Extensive tectonic uplift, magma activity and erosion occurred in Dongsha Island and the adjacent area, where most of the faults in the northeastern SCS were still active during Pliocene and Quaternary. Two groups of faults trending NEE and NW were developed during Late Cenozoic. We conclude that three important tectonic movements, especially Dongsha movement(4.4 - 5.2 Ma) and Liuhua movement (1.4 - 1.89 Ma), controlled the structural framework in the Dongsha rise; whose deformation in the east is stronger than that in the west and whose stress field variation suggests that the tectonic uplift in the study area contributed to magmato-tectonic events correlated to the main collision phases between the East China and Taiwan 5 - 3 and 3 - 0 Ma ago.     

浊流及其相关的深水底形研究进展

从19世纪发现海底浊流现象开始,这一重要的深水沉积过程就引起了地学界的广泛关注。研究发现深水浊流成因的周期阶坎等超临界流底形广泛分布于海底,且与鲍马定义的浊积岩序列有着密切联系。由于浊流事件的不可预测、破坏力强,直接观测设备和技术也比较匮乏,造成对浊流事件进行直接海底观测的工作较少。总结了国内外浊流及其相关底形的研究成果,对浊流分类、底形的形成与演化进行了讨论,列举了国内外几个典型深水区浊流及其相关超临界流底形的研究案例,包括实验、数值模拟和深水底形研究,详细介绍了周期阶坎这一主要的超临界流底形,讨论了周期阶坎的形成与演化过程及其与鲍马序列的对应关系。最后,对浊流及其相关的超临界流底形研究进行了展望。     

DISTRIBUTION AND ORIGIN OF SEDIMENTS ON THE NORTHERN SUNDA SHELF, SOUTH CHINA SEA

ＩＮＴＲＯＤＵＣＴＩＯＮＯｎｅｏｆｔｈｅｍｏｓｔｅｘｔｅｎｓｉｖｅｓｈｅｌｖｅｓｏｆｔｈｅｗｏｒｌｄｌｙｉｎｇｗｉｔｈｉｎｔｈｅｓｏｕｔｈｅｒｎｐａｒｔｏｆｔｈｅＳｏｕｔｈＣｈｉｎａＳｅａｉｓｔｈｅ1850000ｋｍ2ＳｕｎｄａＳｈｅｌｆｌｏｃａｔｅｄｂｅｔｗｅｅｎｔｈｅｔｈｒｅｅｌａｒｇｅｉｓｌａｎｄｓｏｆＳｕｍａｔｒａ,Ｂｏｒｎｅｏ,ＪａｖａａｎｄｍａｉｎｌａｎｄＡｓｉａ(ＬａＦｏｎｄ,1966).ＴｈｅｎｏｒｔｈｅｒｎｐａｒｔｏｆｔｈｅＳｕｎｄａＳｈｅｌｆｉｓｓｅｐａｒａｔｅｄｆｒｏｍｔｈｅＪａｖａＳｅａｓ…     

南海东沙海域天然气水合物与地质构造的关系

构造作用和构造过程是控制天然气水合物发育和赋存的重要地质因素之一。陆坡区复杂的构造运动能够形成良好的气体运移通道以及欠压实、高孔隙的水合物储集空间。东沙群岛邻近海域具有水深变化大、沉积厚度大、沉积速率高和有机质丰富等天然气水合物有利赋存条件,最新的研究已经在该海域发现了天然气水合物赋存的地球物理证据BSR,针对东沙群岛海域广泛发育的断裂、底辟、海底滑坡等构造,开展了其与天然气水合物成藏的关系研究,可以进一步深入了解天然气水合物在东沙群岛不同地质构造中的分布特征与演化,为该区天然气远景评估提供参考。     

琼东南陆坡深水水道主控因素及勘探应用

结合全球海平面变化、气候变化、物源供给特征和地形条件,深入地分析和研究了发育在琼东南盆地陆坡区上新世和更新世地层中水道的形成主控因素及其在深水油气勘探中的应用价值和前景。提出琼东南陆坡上新世水道的主要因素是物源供给,包括来自红河和海南岛的物源,构造活动是关键诱发因素,上新世早期莺歌海盆地发育的大规模滑塌体与该水道的形成关系密切;给出更新世水道形成模式,其形成与第四纪冰期海平面的大幅度下降有关,地震活动诱发了中南半岛的小型山脉河流复苏,并对南海西部陆坡直接供给形成了该期水道。深水水道对于全球海平面变化、陆坡区物源供给情况和陆坡层序界面具有指示作用,并可作为良好的深水油气勘探目标,具有重要的深水油气勘探意义。     

南海沉积物中甲烷水合物的实验研究

The experimental apparatus for gas hydrate in porous sediments is introduced.Under different constant temperature(1.0℃,2.0℃,4.0℃,7.0℃,10.℃),the formation and dissociation of methane hydrate with three kinde of sediments granule(average diameters 0.15mm,0.06mm,0.03mm respectively) are studied. The saturation of methane hydrate in porous sediments is got by measuring the consumption of methane in vesssel. The results find that the saturation increases as formation pressure and porosity of sediments increase. It is also showed that the P-T curve in distilled water,which is accordant with the results from other papets sediments departure to left comparing to the P-T curve in distilled water, which is accordant with the results from other papers involved .