新疆西昆仑汗铁热克一带侏罗纪沉积相与沉积环境分析

新疆西昆仑汗铁热克一带地处塔里木盆地西南缘,构造上属塔里木盆地与西昆仑造山带的结合部位,侏罗纪地层包括积莎里塔什组、康苏组、扬叶组、塔尔尕组和库孜贡苏组。根据岩性、颜色、粒度分析及沉积相标志等方法,将汗铁热克一带侏罗纪沉积环境与沉积相划分为冲积扇、扇三角洲和湖泊相,其沉积特征为侏罗纪早期快速充填,中期稳定沉降,晚期短暂的沉积间断后充填,并系统分析了研究区在整个侏罗纪沉积环境演化规律。     

准噶尔盆地吉木萨尔凹陷梧桐沟组层序地层划分

准噶尔盆地吉木萨尔凹陷二叠系梧桐沟组作为一套重要的储集岩,具有良好的油气成藏前景,但对其层序划分及地层沉积样式的认识一直存在争议。在构造背景分析的基础上,结合岩芯、测井及地震资料,对研究区梧桐沟组层序地层划分及地层沉积样式研究表明,梧桐沟组沉积时期构造强度较弱,地形较为平缓,地层在全区稳定分布;中晚二叠世盆地发生造山运动,吉木萨尔凹陷东南边缘区域经过构造抬升,上部地层遭受不同程度的剥蚀,形成了现今"底平顶削"的地层样式。以凹陷中部少数地层保存较全的井的地层叠加样式分析为基础,通过井-震结合识别不同类型界面,特别是最大湖泛面,建立了区域层序地层格架,即梧桐沟组为一个完整的长期基准面旋回(三级层序),并在其内部识别出5个中期旋回。梧桐沟组地层在不同的层序发育时期表现出不同的旋回叠加样式:下段沉积时期,即最大湖泛面以下,随着可容纳空间的增大,地层表现为明显的退积叠加样式;上段沉积时期,即最大湖泛面以上,随着可容纳空间的减小,地层表现为明显的进积叠加样式,符合沉积物体积分配原理。     

Advances in genetic mechanism research on hummocky and hummocky-like cross-stratifications

Hummocky and hummocky-like cross-stratification(HCS and HCS-like)as the identification criteria for sedimentary environments have recently become confused because of the little knowledge on their genetic mechanism based on the following facts: HCS and HCS-like are often associated with storm deposits and turbidity current deposits,respectively; the views on HCS produced in shallow water environments and HCS-like produced in deep-water environments have been abandoned recently. According to the detail reviews on structural and morphologic characteristics and vertical sequence of HCS and HCS-like from literatures,here we found that: (1) the special features of HCS include the sharp or erosional basal contact,the internal truncation surface,close relationship with swaley cross-stratification,and the missing zone or amalgamation of HCS in vertical sequence;(2) the special features of HCS-like often include various thickness of individual lamina,hummocky layer interbedded with parallel bedding or small-scale cross-bedding under continuous deposition,and alternating sedimentary structures of upper and lower flow regime in vertical sequence. According to hydrodynamic theory and flume experiment achievements,these results show that the genetic mechanism of HCS and HCS-like could be divided into two parts,hydrodynamic mechanism and depositional mechanism. The hydrodynamic mechanism of HCS and HCS-like is same and could be interpreted by vertical vortex generated by baroclinic wave in nature. However,depositional mechanism of HCS and HCS-like is very different: HCS and HCS-like could be interpreted by erosion suspending sand mechanism and suspending sand settling mechanism,respectively,and the special features in HCS and HCS-like are due to the different sediment suspension concentration and depositional flow energy. The division for hydrodynamic and depositional mechanism of HCS and HCS-like is very significant in determining sedimentary environments from depositional flow evolution perspective.     

Tectono-sedimentary evolution of Jurassic–Cretaceous diapiric structures: Miravete anticline,Maestrat Basin,Spain

Integration of extensive fieldwork, remote sensing mapping and 3D models from high-quality drone photographs relates tectonics and sedimentation to define the Jurassic–early Albian diapiric evolution of the N–S Miravete anticline, the NW-SE Castel de Cabra anticline and the NW-SE Cañada Vellida ridge in the Maestrat Basin (Iberian Ranges, Spain). The pre shortening diapiric structures are defined by well-exposed and unambiguous halokinetic geometries such as hooks and flaps, salt walls and collapse normal faults. These were developed on Triassic salt-bearing deposits, previously misinterpreted because they were hidden and overprinted by the Alpine shortening. The Miravete anticline grew during the Jurassic and Early Cretaceous and was rejuvenated during Cenozoic shortening. Its evolution is separated into four halokinetic stages, including the latest Alpine compression. Regionally, the well-exposed Castel de Cabra salt anticline and Cañada Vellida salt wall confirm the widespread Jurassic and Early Cretaceous diapiric evolution of the Maestrat Basin. The NE flank of the Cañada Vellida salt wall is characterized by hook patterns and by a 500-m-long thin Upper Jurassic carbonates defining an upturned flap, inferred as the roof of the salt wall before NE-directed salt extrusion. A regional E-W cross section through the Ababuj, Miravete and Cañada-Benatanduz anticlines shows typical geometries of salt-related rift basins, partly decoupled from basement faults. These structures could form a broader diapiric region still to be investigated. In this section, the Camarillas and Fortanete minibasins displayed well-developed bowl geometries at the onset of shortening. The most active period of diapiric growth in the Maestrat Basin occurred during the Early Cretaceous, which is also recorded in the Eastern Betics, Asturias and Basque-Cantabrian basins. This period coincides with the peak of eastward drift of the Iberian microplate, with speeds of 20 mm/year. The transtensional regime is interpreted to have played a role in diapiric development.     

渤海西部沙东南构造带东营组古地貌特征及对沉积的控制作用

渤海西部海域沙东南构造带处于沙垒田凸起向沙南凹陷的过渡部位,受继承性凸起、 不同时期同沉积断裂和古沟谷多种因素影响,沉积相的发育较为复杂,制约了下步油气勘探.为此,通过分析由地层厚度法恢复的沙东南构造带东营组各三级层序沉积时期的古地貌,明确了研究区发育凸起区、斜坡区、古沟谷、断槽、浅洼和深洼陷区等多种地貌单元.同时,以...     

Strain analysis of a seismically imaged mass‐transport complex,offshore Uruguay

Strain style, magnitude and distribution within mass‐transport complexes (MTCs) are important for understanding the process evolution of submarine mass flows and for estimating their runout distances. Structural restoration and quantification of strain in gravitationally driven passive margins have been shown to approximately balance between updip extensional and downdip contractional domains; such an exercise has not yet been attempted for MTCs. We here interpret and structurally restore a shallowly buried (c. 1,500 mbsf) and well‐imaged MTC, offshore Uruguay using a high‐resolution (12.5 m vertical and 15 × 12.5 m horizontal resolution) three‐dimensional seismic‐reflection survey. This allows us to characterise and quantify vertical and lateral strain distribution within the deposit. Detailed seismic mapping and attribute analysis shows that the MTC is characterised by a complicated array of kinematic indicators, which vary spatially in style and concentration. Seismic‐attribute extractions reveal several previously undocumented fabrics preserved in the MTC, including internal shearing in the form of sub‐orthogonal shear zones, and fold‐thrust systems within the basal shear zone beneath rafted‐blocks. These features suggest multiple transport directions and phases of flow during emplacement. The MTC is characterised by a broadly tripartite strain distribution, with extensional (e.g. normal faults), translational and contractional (e.g. folds and thrusts) domains, along with a radial frontally emergent zone. We also show how strain is preferentially concentrated around intra‐MTC rafted‐blocks due to their kinematic interactions with the underlying basal shear zone. Overall, and even when volume loss within the frontally emergent zone is included, a strain difference between extension (1.6–1.9 km) and contraction (6.7–7.3 km) is calculated. We attribute this to a combination of distributed, sub‐seismic, ‘cryptic’ strain, likely related to de‐watering, grain‐scale deformation and related changes in bulk sediment volume. This work has implications for assessing MTCs strain distribution and provides a practical approach for evaluating structural interpretations within such deposits.     

南海东北部陆架边缘第四纪高分辨率层序地层和沉积体系演化及其控制因素

The northeastern shelf margin of the South China Sea(SCS) is characterized by the development of large scale foresets complexes since Quaternary. Based on integral analysis of the seismic, well logging and paleontological data, successions since ～3.0 Ma can be defined as one composite sequence, consist of a set of regional transgressive to regressive sequences. They can be further divided into six 3 rd order sequences(SQ0–SQ5) based on the Exxon sequence stratigraphic model. Since ～1.6 Ma, five sets of deltaic systems characterized by development of wedge-shaped foresets complexes or clinoforms had been identified. High-resolution seismic data and the thick foresets allowed further divided of sub-depositional sequences(4 th order) of regression to transgression, which is basically consistent with published stacked benthic foram O-isotope records. Depositional systems identified in the study area include deltaic deposits(inner-shelf deltas and shelf-edge deltas), incised valleys, and slope slumping massive deposits. Since ～1.6 Ma, clinoforms prograded from the southern Panyu Lower Uplift toward the northern Baiyun Depression, shelf slope break migrated seaward, whereas the shelf edge of SQ0 migrated landward. The development of incised valleys in the continental shelf increased upward,especially intensive on the SB3 and SB2. The slumping massive deposits increased abruptly since SB2, which corresponds to the development of incised valleys. The evolution of depositional systems of continental slope mainly controlled by the combined influence of sea level changes, tectonic movements, sediment supply and climate changes. Since ～3.0 Ma, relative sea level of the northern SCS had been experienced transgression(～3.0 Ma BP) to regression(～1.6 Ma BP). The regional regression and maximum transgressions of the composite sequences were apparently enhanced by uplift or subsidence related to tectono-thermal events. In addition,climatic variations including monsoon intensification and the mid-Pleistocene transition may have enhanced sediment supply by increasing erosion rate and have an indispensable influence on the development of the incised valleys and 5 sets of deltaic systems since ～1.6 Ma.     

珠江口盆地白云凹陷陆坡区10.5 Ma以来的沉积体系

通过对珠江口盆地白云凹陷陆坡区10.5Ma以来的地震相分析,共识别出席状平行亚平行地震相、透镜状前积地震相、深切河谷地震相、帚状地震相和杂乱地震相,不同的地震相分别代表不同的沉积体系类型。综合所识别的地震相类型,分析了陆架边缘下切谷、浊积扇和陆架边缘三角洲3种主要的沉积体系及其配置关系。物源供给是影响陆坡区沉积体系发育的最重要因素,是沉积体系发育的物质基础,海平面变化和构造运动为沉积体系发育提供了可容纳空间,3种影响因素共同影响了陆坡区沉积体系的发育。     

西沙海槽沉积模式

晚中新世琼东南盆地快速构造沉降,沉积欠补偿形成了西沙海槽。西沙海槽上部高陡带为悬浮沉积体系,下部低缓带为浊流滑塌沉积体系,槽底平缓带为河流沉积体系。不同于浊流沉积小而散,深海河流沉积为稳定的贯穿整个海槽的大储层。由于深海河流沉积体系稳、远、大的特点,其注定成为世界深水油气勘探的主要目标。     

湘西地区晚震旦世黑色岩系地层层序、沉积环境与成因

在对湖南大庸、新晃、沅陵、溆浦和黔阳等地上震旦统—早寒武世初期露头层序地层学的研究表明,湘西地区上震旦统内部存在３个与视海平面变化相对应的超层序,其上限大致可以留茶坡组顶部区域性成磷事件的出现为标志。黑色岩系的形成是海平面上升的结果,尽管该岩系具有色深、层薄和富含有机质的共同特点,但不同层位黑色岩系的岩石化学成分和微量元素组成不同,因此具有不同的沉积环境和形成机制。经研究,晚震旦世金家洞组第二段和寒武纪初期黑色岩系的形成与海底火山和深大断裂的热泉喷流作用有关;而金家洞组第四段和留茶坡组下部黑色岩系的形成