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Paleotopographic controls on facies development in various types of braid-delta depositional systems in lacustrine basins in China 被引量:7
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作者 Dong Feng Hongwen Deng +2 位作者 Zhan Zhou Xiaopeng Gao Longtao Cui 《Geoscience Frontiers》 SCIE CAS CSCD 2015年第4期579-591,共13页
Braid-delta depositional systems are widely developed in most continental basins in China. Research indicates that, for different types of braid delta, the facies sequence and association, which are critical to the pr... Braid-delta depositional systems are widely developed in most continental basins in China. Research indicates that, for different types of braid delta, the facies sequence and association, which are critical to the prediction of the distribution of reservoirs, differ greatly. This study illustrates the differences in braid-delta depositional systems in terms of sedimentary characteristics, associated systems and reser- voir distributions using three typical paleodeltas in western China: the Zhenbei delta of the upper Triassic Yanchang Formation in the Ordos Basin, the Yuanba delta of the upper Triassic Xujiahe Formation in the Sichuan Basin and the Jimsar delta of the upper Permian Wutonggou Formation in the Junggar Basin. A stratigraphic framework was established using seismic data, logs and cores by choosing stable mud sections as regional correlation markers and, topographies of these deltas were reconstructed based on the decompaction and paleobathymetric corrections. Based on both the paleotopography of these deltas and the differences of their sedimentary facies, these braided deltas can be classified into two systems: steep-gradient braid-delta-turbidite system and low-gradient braid-delta-lacustrine system. Moreover, the low-gradient braid-delta-lacustrine system can be further divided into interfingered and sharp contact sub-types according to the contact relation between the delta sands and lacustrine muds. This study shows that the paleotopography of basin margins strongly controls the accommodation as braid deltas prograde into lacustrine basins and, influences the location of the shoreline in response to changes in the lake level. Furthermore, paleotopography plays a significant role in facies and reservoir distribution which is important for petroleum exploration and development. 展开更多
关键词 Paleotopography Braid deltas facies Basin margin Lacustrine basins
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Formation of greigite under different climate conditions in the Yellow River delta 被引量:1
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作者 WANG YongHong ZHANG WeiGuo +2 位作者 LIU XiuJin LI GuangXue LIU Meng 《Science China Earth Sciences》 SCIE EI CAS CSCD 2015年第2期300-308,共9页
Formation and preservation of greigite can indicate the physicochemical characteristics of sedimentary environment. Presence of greigite can be diagnosed in the late Pleistocene fluvio-lacustrine sedimentary layers of... Formation and preservation of greigite can indicate the physicochemical characteristics of sedimentary environment. Presence of greigite can be diagnosed in the late Pleistocene fluvio-lacustrine sedimentary layers of 29.4–29.7 and 26.1–27.1 m in core ZK30 of the Yellow River delta, based on analysis of particle size, magnetic properties, scanning electron microscope(SEM) and X-ray diffraction(XRD) measurements. These layers are the transition zones from shallow marine facies to fluvio- lacustrine facies, and from fluvio-lacustrine facies to salt marsh facies in an ascending order, respectively. They are characterized by higher SIRM and SIRM/χ(>30 kA m-1) values than those of other layers, suggesting the possible existence of greigite. Both SEM and XRD analyses confirm its presence. However, sediment layer of 29.4–29.7 m are coarser, and greigite coexists with pyrite, but sediment layer of 26.1–27.1 m are finer and the occurrence of greigite is not accompanied by pyrite. The different occurrence of greigite in the two layers suggests that different climate condition and sedimentary environment control its formation and preservation. 展开更多
关键词 delta facies lacustrine sedimentary pyrite Yellow shallow preservation abundant finer
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