Geophysical investigations of crust-scale structural model of the Qiongdongnan Basin, Northern South China Sea

Rifting of the Qiongdongnan Basin was initiated in the Cenozoic above a pre-Cenozoic basement, which was overprinted by extensional tectonics and soon after the basin became part of the rifted passive continental margin of the South China Sea. We have integrated available grids of sedimentary horizons, wells, seismic reflection data, and the observed gravity field into the first crust-scale structural model of the Qiongdongnan Basin. Many characteristics of this model reflect the tectonostratigraphic history of the basin. The structure and isopach maps of the basin allow us to reconstruct the history of the basin comprising: (a) The sediments of central depression are about 10 km thicker than on the northern and southern sides; (b) The sediments in the western part of the basin are about 6 km thicker than that in the eastern part; (c) a dominant structural trend of gradually shifting depocentres from the Paleogene sequence (45–23.3 Ma) to the Neogene to Quaternary sequence (23.3 Ma–present) towards the west or southwest. The present-day configuration of the basin reveals that the Cenozoic sediments are thinner towards the east. By integrating several reflection seismic profiles, interval velocity and performing gravity modeling, we model the sub-sedimentary basement of the Qiongdongnan Basin. There are about 2–4 km thick high-velocity bodies horizontal extended for a about 40–70 km in the lower crust (v > 7.0 km/s) and most probably these are underplated to the lower stretched continental crust during the final rifting and early spreading phase. The crystalline continental crust spans from the weakly stretched domains (about 25 km thick) near the continental shelf to the extremely thinned domains (<2.8 km) in the central depression, representing the continental margin rifting process in the Qiongdongnan Basin. Our crust-scale structural model shows that the thinnest crystalline crust (<3 km) is found in the Changchang Sag located in the east of the basin, and the relatively thinner crystalline crust (<3.5 km) is in the Ledong Lingshui Sag in the west of the basin. The distribution of crustal extension factor β show that β in central depression is higher (>7.0), while that on northern and southern sides is lower (<3.0). This model can illuminate future numerical simulations, including the reconstruction of the evolutionary processes from the rifted basin to the passive margin and the evolution of the thermal field of the basin.     

2009年冬、夏季南海北部超微型浮游生物的分布特征及其环境相关分析

2009年2月(冬季)和8月(夏季)在南海北部海域(nSCS)采用流式细胞术对聚球藻、原绿球藻、超微型光合真核生物3类超微型光合浮游生物和异养浮游细菌的丰度和碳生物量的时空分布特征进行了研究,并分析了其与环境因子之间的关系。结果表明,夏季聚球藻和原绿球藻的平均丰度高于冬季,超微型光合真核生物和异养浮游细菌的丰度反之,为冬季高于夏季。聚球藻、超微型光合真核生物和异养浮游细菌在富营养的近岸陆架海域丰度较高,而原绿球藻高丰度则出现在陆坡开阔海域。在垂直分布上,聚球藻主要分布在跃层以上,跃层以下丰度迅速降低;原绿球藻高丰度主要出现在真光层底部;超微型光合真核生物在水层中的高值同样出现在真光层底部,且与Pico级份叶绿素a浓度分布一致;异养浮游细菌在水体中的分布与聚球藻类似。这些分布格局的差异,取决于环境条件的变化和4类超微型浮游生物生态生理适应性的差异。在超微型光合浮游生物群落中,各类群碳生物量的贡献因季节和海域类型的不同而发生变化:聚球藻在夏季近岸陆架区占超微型光合浮游生物总碳生物量的41%,原绿球藻在陆坡开阔海成为主要贡献者(50%),超微型光合真核生物碳生物量以冬季为高(在近岸陆架区占比68%)。冬、夏季异养浮游细菌碳生物量均高于超微型光合浮游生物碳生物量。     

矿物标型六性及其在胶东金矿中的应用

目前矿物标型研究和应用已进入一个新的阶段。作者从哲学的高度,把国内外矿物标型特征的分散研究加以集中概括和总结,提出了“矿物标型六性”的普遍规律,即普遍性、特殊性、变化性、相应性、继承性和分带性,对矿物标型特征研究具重要的指导意义。这些规律在胶东金矿中得到广泛应用,并已取得良好效果。     

Demersally drifting invertebrates from Kongsfjorden,Svalbård (Arctic Ocean)–a comparison of catches from drift-pump and drift-nets

Demersally drifting organisms were collected at Ny Ålesund (Svalbård–Arctic Ocean) to study the taxon composition and relative abundances in the Arctic summer. Catch potentials of two collection devices for demersal drift were compared. A lowvolume submersible drift-pump and a drift-net unit were employed for the collection of demersally drifting biota, particularly for shallow aquatic habitats. With the exception of Appendicularia, Chaetognatha, Coelenterata, and Ctenophora, which were damaged at times, the pump catches were in good condition and sufficient for identification and quantification of less mobile fauna. A comparison of the two devices revealed that the drift-pump collected more specimens than the drift-net. However, the drift-net may have caused an underestimation of the abundances of invertebrates. No differences in identified taxon number and indices of richness, evenness and diversity were found. However, the proportion of invertebrate animals in the two devices was different for the three groups: zooplankton, macrofauna and meiofauna. At Svalbård, zooplankton, larvae of macrofauna, and meiofauna were successfully collected by the two collecting devices. However, the catchibility of the two devices in collecting various invertebrate taxa was different and, therefore, a sound ‘Device Effect’ was revealed.     

秦皇岛地质环境综述

通过大量野外调查和对已有成果的分析,发现该地区地质环境破坏严重,并有恶化的趋势.该地区主要地质环境问题包括地质灾害、水环境污染、海水入侵和海岸蚀退,多数为人为因素引发,自然灾害是次要灾害.最后针对不同的地质环境问题提出综合保护建议.     

中更新世以来西菲律宾海上层水体结构演化特征——来自钙质超微化石Florisphaeraprofunda的证据

MD06-3050岩芯位于西菲律宾海吕宋岛以东本哈姆高原,利用钙质超微化石下透光带种属Florisphaera profunda占总颗石的相对丰度,恢复了中更新世以来该海区的上层水体结构演化特征。结果显示,西菲律宾海区自1040ka以来,温跃层/营养跃层经历了由浅—深—浅—深的长周期变动,可能是由于全球碳库的长周期变化对气候系统的大规模调整所致; 同时温跃层/营养跃层也具有明显的冰期-间冰期旋回性特征。温跃层变动的另一个重要特征是在中布容事件前后呈现出相反的冰期-间冰期变化趋势,认为可能是由东亚冬、夏季风强度变化引起。     

吉林省中,新生代陆缘弧发展演化阶段及其类型划分

依吉林省中，新生代陆缘弧发展演化特征，将其划分为三个发展演化阶段，即陆缘弧隆断阶段（Ｔ３－Ｋ１）陆缘弧隆拗阶段（Ｋ２－Ｋ２）和陆缘弧裂解阶段（Ｅ－Ｑ）。根据陆缘弧发展演化过程中的性状变化特点，陆缘弧类型可相应地划分在挤压型陆缘弧，盆岭型陆缘弧和裂解型陆缘弧。     

汶川地震同震模型新解及震后InSAR观测和初步分析

汶川地震的形变观测在一定程度上来说,取得了前所未有的成功,特别是在龙门山这样一个特殊的地质构造单元上。通过干涉雷达(InSAR)手段获得断层上盘的形变观测,用C波段雷达观测几乎是不可能的,因为剧烈的地面起伏和致密的植被覆盖会使得雷达后向散射信号在观测期间变得完全不相干。同时超厚的水汽分布,使得大气对雷达波的延迟作用变强,造成显著的观测误差。然而,利用L波段雷达观测,前面一个问题得到部分解决;同时,日本宇航机构JAXA在震后紧急调整卫星轨道,获得了相当一部分覆盖汶川地震的小基线干涉像对,进一步降低了干涉去相干作用,最终使得我们得到了比较全面的InSAR形变观测结果。