Balanced Cross Section for Restoration of Tectonic Evolution in the Southwest Okinawa Trough     

吴时国  倪祥龙  郭军华 《中国地质大学学报(英文版)》2007,18(1):1-10

On the basis of the multi-channel seismic data and the other data, using 2DMove software, the tectonic evolution in three seismic profiles was restored since Pliocene. The tectonic restoration results show that: (1) the initial active center lay in the west slope and then was transferred to east and south via trough center during the evolution process; (2) several main normal faults controlled the evolution of the southern Okinawa Trough; (3) since Late Pliocene, the southern Okinawa Trough has experienced two spreading stages. The early is depression in Early-Middle Pleistocene and the late is back-arc spreading in Late Pleistocene and Holocene, which is in primary oceanic crust spreading stage.  相似文献   

A Comprehensive Investigation of an Offshore Active Fault in the Western Sagami Bay, Central Japan   总被引：1，自引：0，他引：1  

Izumi SAKAMOTO  How Kin WONG 《《地质学报》英文版》2002,76(3):300-307

Offshore active faults, especially those in the deep sea, are very difficult to study because of the water and sedimentary cover. To characterize the nature and geometry of offshore active faults, a combination of methods must be employed. Generally, seismic profiling is used to map these faults, but often only fault-related folds rather than fracture planes are imaged. Multi-beam swath bathymetry provides information on the structure and growth history of a fault because movements of an active fault are reflected in the bottom morphology. Submersible and deep-tow surveys allow direct observations of deformations on the seafloor (including fracture zones and microstructures). In the deep sea, linearly aligned cold seep communities provide indirect evidence for active faults and the spatial migration of their activities.The Western Sagami Bay fault (WSBF) in the western Sagami Bay off central Japan is an active fault that has been studied in detail using the above methods. The bottom morphology, fracture  相似文献   

南极普里兹湾柱样中石英颗粒的表面结构   总被引：6，自引：0，他引：6       下载免费PDF全文

王祥珍  吴时国  李传荣  陈虹勋  罗又郎 《极地研究》1997,9(2):12-25

本文统计分析了南极普里兹湾陆坡区一个柱样（ＮＰ９５１）１３个层位的石英颗粒的形态和表面结构。石英表面呈现出强烈的冰川运动和较弱的化学溶蚀－沉淀作用留下的表面特征，表明该沉积物主要是处于低能海洋环境中的冰碛物。石英颗粒因化学溶蚀－沉淀作用形成的组合表面特征的定量统计结果与矿物的Ｘ射线衍射和微体古生物的分析结果相对应，能较好地解释该海区经历的沉积环境和古气候变化。  相似文献   

Seismic profiles across the middle Tan-Lu fault zone in Laizhou Bay, Bohai Sea, eastern China   总被引：4，自引：0，他引：4  

Zhaohua Yu  Shiguo Wu  Dongbo Zou  Deyong Feng  Hanqing Zhao 《Journal of Asian Earth Sciences》2008,33(5-6):383-394

The stratigraphic architecture, structure and Cenozoic tectonic evolution of the Tan-Lu fault zone in Laizhou Bay, eastern China, are analyzed based on interpretations of 31 new 2D seismic lines across Laizhou Bay. Cenozoic strata in the study area are divided into two layers separated by a prominent and widespread unconformity. The upper sedimentary layer is made up of Neogene and Quaternary fluvial and marine sediments, while the lower layer consists of Paleogene lacustrine and fluvial facies. In terms of tectonics, the sediments beneath the unconformity can be divided into four main structural units: the west depression, central uplift, east depression and Ludong uplift. The two branches of the middle Tan-Lu fault zone differ in their geometry and offset: the east branch fault is a steeply dipping S-shaped strike-slip fault that cuts acoustic basement at depths greater than 8 km, whereas the west branch fault is a relatively shallow normal fault. The Tan-Lu fault zone is the key fault in the study area, having controlled its Cenozoic evolution. Based on balanced cross-sections constructed along transverse seismic line 99.8 and longitudinal seismic line 699.0, the Cenozoic evolution of the middle Tan-Lu fault zone is divided into three stages: Paleocene–Eocene transtension, Oligocene–Early Miocene transpression and Middle Miocene to present-day stable subsidence. The reasons for the contrasting tectonic features of the two branch faults and the timing of the change from transtension to transpression are discussed.  相似文献   

山东省东平湖桡足类的初步研究   总被引：3，自引：0，他引：3  

林育真  李玉仙 《海洋湖沼通报》1997,(4):32-36

１９９４年，分别于枯水期，丰水期，平水期对东平湖桡足类群落结构进行了调查研究，同时探讨了东平湖桡足类区系结构特征。  相似文献   

Geomorphology, sedimentary processes and development of the Zenisu deep-sea channel, northern Philippine Sea     

Shiguo Wu  Narumi Takahashi  Hidekazu Tokuyama  How Kin Wong 《Geo-Marine Letters》2005,25(4):230-240

The Zenisu deep-sea channel originates on the Izu-Ogasawara island arc, and disappears in the Shikoku Basin of the Philippine Sea. The geomorphology, sedimentary processes, and the development of the Zenisu deep-sea channel were investigated on the basis of swath bathymetry, side-scan sonar imagery, submersible observations, and seismic data. The deep-sea channel can be divided into three segments according to the downslope gradient and channel orientation. They are the Zenisu Canyon, the E–W fan channel, and the trough-axis channel. The sediment fill is characterized by turbidite and debrite deposition and blocky–hummocky avalanche deposits on the flanks of the Zenisu Ridge. In the Zenisu Canyon and the Zenisu deep-sea channel, sediment transport by turbidity currents generates sediment waves (dunes) observed during the Shinkai 6500 dive 371. The development of the Zenisu Canyon is controlled by a N–S shear fault, whereas the trough-axis channel is controlled by basin subsidence associated with the Zenisu Ridge. The E–W fan channel was probably affected by the E–W fault and the basement morphology.  相似文献   

南沙海区海洋沉积学的研究进展     

罗又郎  吴时国 《地球科学进展》1995,10(2):143-147

简要介绍了中国科学南沙综合考察队有关海洋沉积学十年科考取得的研究进展，包括现代沉积作用过程，沉积地球化学，礁碳酸盐地质学，盆地分析，古海洋学与全球变化等方面。  相似文献   

Research Progress and Challenges of Submarine Cyclic Steps     

Dawei Wang  Yue Sun  Shaowen Si  Shiguo Wu 《地球科学进展》1986,35(9):890-901

Cyclic steps structure derived from the supercritical flows is one of the common bedforms， which is commonly found in sedimentary systems such as delta systems， deep-water canyon-channel systems， and carbonate platforms. In this paper， the research progresses of cyclic steps were introduced from the aspects of sedimentary environment， the features of bedforms， sedimentary structure， formation mechanism， and numerical simulation. The Research scale differences associated with the survey techniques or study methods， such as the ship survey and AUV-based multi-beams， sub-bottom profiles， multichannel seismic， the field outcrop， and numerical simulation were discussed. Finally， the breakthrough directions of the cyclic steps research were given. The combining method of ground penetrating radar， multichannel seismic， drilling and well logging were used to accurately detect the location of field outcrop thalweg. Within the area with water depth greater than 500 meters， the blending of multi-data for the cyclic steps research involved the AUV-based and the ship multi-beams， sub-bottom profiles， and multichannel seismic data. With the in situ samples and observation data obtained by human occupied vehicles， three-dimensional numerical simulation was developed to establish a set of dynamic simulation equations suitable for the real cyclic steps. Therefore， the high resolution three dimensional mode of the deep-water cyclic steps could be obtained more accurately.  相似文献   

A New Index Developed for Fast Diagnosis of Meteorological Roles in Ground-Level Ozone Variations     

Weihua CHEN  Weiwen WANG  Shiguo JIA  Jingying MAO  Fenghua YAN  Lianming ZHENG  Yongkang WU  Xingteng ZHANG  Yutong DONG  Lingbin KONG  Buqing ZHONG  Ming CHANG  Min SHAO  Xuemei WANG 《大气科学进展》2022,39(3):403-414

China experienced worsening ground-level ozone(O₂) pollution from 2013 to 2019. In this study, meteorological parameters, including surface temperature(T₂), solar radiation(SW), and wind speed(WS), were classified into two aspects,(1) Photochemical Reaction Condition(PRC = T₂× SW) and(2) Physical Dispersion Capacity(PDC = WS). In this way, a Meteorology Synthetic Index(MSI = PRC/PDC) was developed for the quantification of meteorology-induced ground-level O₂pollution. The positive linear relationship between the 90 th percentile of MDA8(maximum daily 8-h average) O₂concentration and MSI determined that the contribution of meteorological changes to ground-level O-3 varied on a latitudinal gradient, decreasing from ~40% in southern China to 10%–20% in northern China. Favorable photochemical reaction conditions were more important for ground-level O₂pollution. This study proposes a universally applicable index for fast diagnosis of meteorological roles in ground-level O₂variability, which enables the assessment of the observed effects of precursor emissions reductions that can be used for designing future control policies.  相似文献   

裂后岩浆活动中岩床复合体的特征:以南海北部和南极西罗斯海地区为例     

张峤  高金耀  吴时国 《大地构造与成矿学》2017,41(6)

由于蕴含着潜在的油气勘探和资源储藏信息,岩床复合体在全球范围内被广泛研究。本文基于南海北部三维地震资料以及南极罗斯海地区二维多道地震资料,对岩床复合体的形态特征及分布进行分析,对两个地区岩床复合体的形成时间进行判断,阐述岩床复合体的侵位机制。研究发现,岩床复合体代表性产状除了菱形、碟形及复合型外,还存在沿着层位平行侵入的板状,推测它可能是夭折了的岩床侵入体,以及由几个小型岩床堆叠而成的透镜状岩床复合体。分布上,南海北部岩床主要发育于珠江口盆地白云凹陷三维工区西部,东部只零星可见;南极西罗斯海岩床主要发育于西北角的阿黛尔盆地内。根据岩床上覆的强制褶皱结合区域构造背景,推测南海北部岩床复合体的形成时间为早中新世(15.5 Ma),海底扩张结束之时。残余岩浆将盆地内裂谷时期形成的断层作为岩浆运移的通道,并最终在断层终点处即下中新统近海相砂泥岩地层中实现侵位。南极西罗斯海岩床复合体的形成时间则非常晚,不早于5.5 Ma。该区这期岩浆活动可能与构造作用无关,而是受到冰川消融的影响。研究发现岩床复合体内部的岩床个体互相供给,即深部的大岩床为上覆浅层的小岩床提供岩浆供给,并且互相组合,形成大的岩床复合体。然而,每个岩床复合体则可能由不同的岩浆供给发育而成。  相似文献