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821.
沉积有机相在陆相层序地层格架中的分布特征--以吐哈盆地台北凹陷及准噶尔盆地南缘中侏罗世煤系为例 总被引:15,自引:1,他引:14
综合应用有机岩石学、地球化学及孢粉学的研究方法,对吐哈盆地台北凹陷及准噶尔盆地南缘J2x煤系的沉积有机相在陆相层序的格架中的分布特征进行了探讨。研究表明,一般情况下,各类沉积有机相在层序地层格架纵向上以湖侵体系域为中心对称分布,生烃能力最强的烃源岩出自湖湾-半深湖有机相,其位置一般出现在湖侵体系域中部,向上向下,烃源岩生烃能力依次变差。 相似文献
822.
The wind-water two-phase erosion and sediment-producing processes in the middle Yellow River basin, China 总被引:8,自引:0,他引:8
XU Jiongxin 《中国科学D辑(英文版)》2000,43(2):176-186
Based on data from the middle Yellow River basin, a wind-water two-phase mechanism for erosion and sediment-producing processes
has been found. By using this mechanism, the extremely strong erosion and sediment yield in the study area can be better explained.
The operation of wind and water forces is different in different seasons within a year. During winter and spring, strong wind
blows large quantities of eolian sand to gullies and river channels, which are temporally stored there. During the next summer,
rainstorms cause runoff that contains much fine loessic material and acts as a powerful force to carry the previously prepared
coarse material. As a result, hyperconcentrated flows occur, resulting in high-intensity erosion and sediment yield. 相似文献
823.
Several intervals rich in barite nodules occur in the mid-Cretaceous marls of the Vocontian Trough (SE France). These concretions, which grew on heterogeneities in the sediment, are arranged as horizons parallel to the bedding, and are often associated with carbonate and phosphate nodules. Detailed sedimentological and stratigraphical observations suggest that they represent the consequence of short-term pauses in sedimentation during early diagenesis, but the most important occurrences of barite are below prominent discontinuities. This may be explained by the frequency of pauses in sedimentation caused by a progressive starvation, or an increase in the energy of bottom-water currents. The high number of barite occurrences on the basin margins is directly linked to the recurrence of sedimentary breaks. The geochemical data show that the host sediment corresponds to a pelagic setting, far from hydrothermal influences, but generally in a restricted, dysoxic to suboxic, depositional environment. The sulphur isotopic composition of the barite sulphate (+16 to +76‰ rel. CDT) supports the hypothesis of an early diagenetic origin of the barite nodules. Their genesis may be explained by the fixation of a diagenetic front corresponding to the penetration of a sulphate reduction zone from the seawater–sediment interface down in the sediment which is in contact with barium-rich porewaters expelled upwards as a consequence of compaction. The barium of biogenic origin, initially stored in the underlying black shale, was mobilized under strongly reducing conditions. Such fixation is normally induced by a pause or a stop in sedimentation due to starvation or renewed bottom-water circulation. Together with other concretions, the barite nodules mark condensed stratigraphic intervals and often represent major breaks. As such they shed light on variations in sedimentary activity and their importance in the sedimentology and stratigraphy of pelagic marly sequences cannot be ignored. 相似文献
824.
Catastrophic flooding of an aeolian dune field: Jurassic Entrada and Todilto Formations, Ghost Ranch, New Mexico, USA 总被引:2,自引:0,他引:2
Surveyed outcrops of the Middle Jurassic Entrada Sandstone at Ghost Ranch, New Mexico, show the unusual occurrence of preserved aeolian dune palaeotopography buried beneath subaqueous strata. The preserved dune remnants have relief up to 35 m, trend NNW, and show internal scalloped cross-strata dipping to the WSW, with small sets occurring as both topsets and bottomsets. Outcrop data are best satisfied in computer models by 50 m high, sinuous bedforms that migrated to the WSW, while the sinuosity migrated alongcrest to the NNW. Superimposed small dunes occurred upon the stoss slope, and at the basal lee of the main bedform where they migrated alongslope to the NNW. Remnant dune palaeotopography is buried by onlapping, subaqueous, largely structureless sandstones believed to be derived by mass wasting of the upper portions of the dunes and deposited as sediment-gravity flows that infilled between the dunes. Preservation of dune palaeotopography beneath mass-flow deposits, with no evidence for gradually rising water, argues that flooding of the Entrada dune field was geologically instantaneous. The thickness and lithology of the overlying Todilto Formation conform to slight remnant palaeotopography on the Entrada surface. The Todilto is a laminated limestone and thinnest over remnant dune crestal areas, but thickens and increases in gypsum content downslope until it abruptly yields to a gypsum mound positioned over a remnant interdune hollow. The Todilto laminations are interpreted as seasonal varves deposited below wave base in a density-stratified water body. The flooding event that gave rise to the controversial Todilto water body occurred during Entrada time, with Todilto deposition occurring within an already substantial water body. 相似文献
825.
利用干酷根镜质体反射率等多项指标分析了吐哈盆地杜家台构造侏罗系生油岩的热演化特性,认为该构造上生油岩生油门际在3560m左右。侏罗系七克台组、三间房组、三工河组的生油岩处于未成熟阶段,西山窑组和八道湾组也尚进入生油阶段。八道湾组煤系地层成熟度高,是入亮煤阶段,煤成气生成量多,是重点勘探层。 相似文献
826.
孝泉气田CX108井侏罗系储层压裂施工失败原因分析 总被引:1,自引:0,他引:1
孝泉气田我系蓬莱镇组气藏属致密砂岩气藏,储层压裂改造技术一直没有突破,障碍了对该区块地勘探开发步代,本文重点以CX108井裂度验为例,从地质因素和压裂施工参数入手,对造成该井压旗子工失败的多种原因作出详细分析,据此提出一系裂建议,以期为孝泉为气田压裂改造技术的突破作出有益的探索。 相似文献
827.
828.
Li Chang’an Yin Hongfu Zhang Yufen Gu Yansheng Faculty of Earth Sciences China University of Geosciences Wuhan China 《中国地质大学学报(英文版)》2000,11(3)
CAUSE FOR FL OODS IN MIDDL E REACH OF YANGTZERIVERFlood,a kind of interface disaster,occurs atthe interfacebetween atmosphere and lithosphere. Flood happens when at-mosphere and lithosphere interplay and couple each other(ofcourse,biosphere may also join in this) . Both meteorologicaland geographical factors can bring about flood;the formercontrols the time of flood and the latter controls the place ofdisaster. The second Neocathaysian tectonic subsidence area(L i,1973) is the… 相似文献
829.
BIOGEOGRAPHIC RELATIONS OF THE JURASSIC PECTINOIDA AND OSTREOIDA (BIVALVIA) BETWEEN TANGGULA AND OTHER AREAS 总被引:2,自引:0,他引:2
Sha Jingeng 《地学前缘》2000,(Z1)
BIOGEOGRAPHIC RELATIONS OF THE JURASSIC PECTINOIDA AND OSTREOIDA (BIVALVIA) BETWEEN TANGGULA AND OTHER AREAS 相似文献
830.