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    2011, Volume 18 Issue 4
    18 July 2011
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    The lithofacies paleography of the northern margin of Yangtze Block in Changxing Phase of Late Permian.
    2011, 18(4): 1-8. 
    Abstract ( 2383 )   PDF (7139KB) ( 1056 )  

    The northern margin of Yangtze Block borders on Qinling orogen. In Changxing Phase, its rockstratigraphic unit includes Changxing Formation and Dalong Formation. Changxing Formation is composed of carbonate sediment and its main sedimentary facies include platform facies, platform edge reef and bank facies, and platform edge's slope facies. But Dalong Formation is mainly composed of a suite of gray/black thin bedded silica rock, bass and a little interbed of cryptite. All these are deposited in somewhat deeper basin. The research result shows that the range of deeper basin is from west to east, i.e., from the western Guangyuan to Wangchang to Nanjiang to the western Hubei province. And the deeper basin separated the Yangtze Block from the North China Block. This kind of pattern implies the direction of exploration and may indicate that the Yangtze Block and the North China Block have already joined as a whole land block before the Changxing Phase.

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    Sedimentary facies of dinosaur trackways and bonebeds in the Cretaceous Jiaolai Basin, eastern Shandong, China, and their paleogeographical implications.
    2011, 18(4): 9-24. 
    Abstract ( 4301 )   PDF (14072KB) ( 7022 )  

    The core issue of taphonomy is to study the sedimentary facies of fossilbearing rocks, reconstruct their depositional environments, and understand the paleogeographical background before and after the burying of fossils at different scales. One of current taphonomy interests focuses on the mass extinction or bonebeds of dinosaurs, including their paleogeography, paleoenvironment and preservation. Numerous Jurassic and Cretaceous dinosaur fossil sites have been discovered in China, making it number 1 in the world in terms of richness of dinosaur genera and species. The terrestrial Cretaceous Laiyang, Qingshan and Wangshi groups (13065 Ma), in ascending order, are widely distributed in Jiaolai Basin of eastern Shandong Province, China. Lithologically, the Early Cretaceous Laiyang Group consists of fluvial and lacustrine sediments and the Early Cretaceous Qingshan Group is mainly composed of medium or acid volcanic rocks and pyroclastic rocks interbeded with sedimentary rocks. The Late Cretaceous Wangshi Group is mainly deposits of alluvial fan, mud flow and braidedchannel facies in the lower part; shallow lacustrine deposits and rhythmic fluvial sediments of mudstone, siltstone, sandstone or soils (palesoil) in the middle part; and rhythmic depositions of siltymuddy conglomerate, sandstone and siltstone of mud flow, braidedchannel and flooding plain facies, locally interbeded with basalt in the upper part. Sedimentary successions and facies associations of the Cretaceous Jiaolai Basin indicate an evolution of basin and sedimentary paleogeography, i.e., from alluviallacustrine environment in humid and warm climate in the Early Cretaceous to an alluvial environment in hot and drought climate towards the Late Cretaceous. Biota of the Early Cretaceous in Jiaolai Basin is identical to the Jehol Biota in the northern areas of North China. In the Laiyang Group, a plentiful of dinosaur (theropod, sauropod and ornithopod) footprints were excellently preserved, as well as a few small dinosaurs (Psittacosaurus) or single bones of pterosaurs. A number of dinosaur bonebeds or mass extinction appeared in the middle or upper part of the Late Cretaceous Wangshi Group in Zhucheng. Until now, over ten genera and species of dinosaurs, including three species of horned dinosaurs, three species of tyrannosaurs, two species of hadrosaurs, and some specimens of ankylosaur and coelurosaurs have been unearthed. Among them, hadrosaurs account for the overwhelming majority (at least more than 95%). Most of dinosaur bones in mud flow deposits are disarticulated, only with a few articulated. Varioussized bones were mixed in and rare sorting. Bone condition variation is believed to represent deposits of mixture of allochthonous faunal elements by geological events. Three types of taphonomic sedimentary microfacies are recognized: mud flow, flooding plain and braidedchannel. Mud flow deposits are major taphonomic occurrence among these three taphonomic microfacies, indicating a preferential preservation of dinosaur material, which are believed to represent the end product of mass burying of dinosaurs and dynamic mechanism through which bones were gathered and accumulated in the Late Cretaceous. The top Wangshi Group in Laiyang mainly consists of the rhythmic depositions of purple red conglomerate, sandstone, siltstone and soils interpreted as flooding plain and braidedchannel microfacies respectively, indicating a prevailing hot and drought climate at the end of the Late Cretaceous. All bones are, here, disarticulated and rare articulated, isolated and single, highly abraded and preserved within flooding plain microfacies under large scale braided channel sandstones. Bone condition variation is believed to represent redeposited after a longer transportation by braidedchannels and alterations before or after burying. Furthermore, evolution of Jiaolai Basin and its paleogeographic environment, paleoecology and dinosaur fauna in the Cretaceous are briefly discussed as well.

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    Geochemistry of the Neoproterozoic molartooth carbonates in Dalian, eastern Liaoning, China, and its geological implications.
    2011, 18(4): 25-40. 
    Abstract ( 2415 )   PDF (6068KB) ( 842 )  

    The Molartooth carbonate (briefly, MT) is one type of carbonates which is developed widely with special origin implication. Until now, MT structures have been found in over 50 stratigraphic sections of Mesoand Neoproterozoic in more than twenty regions in the world. Since more than one hundred years, the research of MT has achieved significant progress, but it is still a question for geologists. Studying from the relationship between MT and host rocks, especially the relationship between MT and geochemical characteristic of host rocks and its geological implication, and using testing methods such as thin section, electron probe, backscattering spectrometry, cathodoluminescence (CL), and the systematic testing of C, O, Sr isotopes, the paper focuses on the composition, structure, microscopic structure of MT and its host rocks from Neoproterozoic Nanguanling, Yingchengzi and Xingmincun formations in Dalian, eastern Liaoning Province. It is proved that MT is the production of original or early diagenesis, which was crystallized or diagenesised from the original sea water directly. MT and its host rocks have similar geochemistry with syngenetic or Penecontemporaneous characteristics, and formed in warm normal oceanic environment and disappeared before glaciagenic Sturtian Period. The analogy of the Sr and C isotopes of MT to the global theory curves of Mesoand Neoproterozoic Sr and C isotopes shows that the geological age of the Neoproterozoic Nanguanling and Yingchengzi Formations in Dalian is 760950 Ma, and the Xingmincun Formation is 720800 Ma. The Neoproterozoic strata in JiaoLiaoXuHuai subprovince are well correlated.

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    Research of lithofaciespalaeogeography of the Middle Permian in the region of KiamuszeInner Mongolia, Northeast China.
    2011, 18(4): 41-51. 
    Abstract ( 1870 )   PDF (7305KB) ( 865 )  

     The mapping units of lithofacies palaeogeography map were strictly selected in accordance with the principles of isochronous comparison. On the basis of the sections measured in field survey and the detailed study of fine sedimentary microfacies, we have identified the marine facies(shallow marine subfacies, half deep marine subfacies)and delta facies(delta front: underwater distributary channel, estuary dam and the former delta)sedimentation in outcrop profile in northeast China. Based on the outcrop point measurement, from point to line and from line to plane, the paleoenvironments has been analyzed. On the basis of fine division in the field profile microfacies and combined with regional geological data, the maps of stratigraphic thickness, sandstone thickness, mudstone thickness, carbonate rocks thickness, the ratio of sandstone in the formation, the ratio of mudstone in the formation, the percentage of rocks, etc. have been plotted. On the basis of quantitative analysis and combining the principle of advantages of phase,the lithofacies palaeogeography map of Middle Permian in Northeast region was drawn. In this region mainly developed delta facies, carbonate platform facies, neriticbathyal phase. Delta facies mainly distributed in the west, northeast, and southeast; the ancient land mass nearby is the main source system;the carbonate platform is mainly in the northwest and east of the work area;the neriticbathyal phase is widely distributed.

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    Progress in the study of microbial dolomite model.
    2011, 18(4): 52-64. 
    Abstract ( 1923 )   PDF (2877KB) ( 1619 )  

    Dolomite Problem has been a topic much attention being paid to in sedimentology for a long time. Recently, the recognition that microbes play an important role at low temperatures no matter in modern natural environments or in bacterial culture experiments provides a new perspective and develops a new field. Based on documented data, this article combining the microbial geochemistry conditions in bacterial culture experiments with the natural environmental conditions divides microbial dolomite mechanism into two modes: the anaerobic and the aerobic modes, and the authors detail the microbial dolomite mechanisms including sulfate-reducing bacteria, methanogenic Archaea and halophilic aerobic bacteria. The morphological characteristics of dolomite associated with microbe includ

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    Basin evolutions of the Tuotuohe River basin and sedimentary response to the uplifting of the QinghaiTibet Plateau in the PaleogeneNeogene.

    2011, 18(4): 65-76. 
    Abstract ( 3213 )   PDF (11232KB) ( 6233 )  

    Abstract:On the basis of sedimentary sequences, regional unconformities, lithological associations and distributions of the Paleogene and the Neogene in the Tuotuohe River Basin on the QinghaiTibet Plateau, four shallowingupward sequences consisting of, in an ascender order, the Tuotuohe Formation,Yaxicuo Formation, Wudaoliang Formation and Quguo Formation were recognized, which furthermore constructed two complete continental orogenic molasses successions. Current research indicates that Tuotuohe River Basin was involved in a successive evolution history, i.e., foreland basin (56.545.0Ma), strikeslip pullapart basin (45300 Ma), uplifted residual basin (235160Ma), foreland basinrestricted basinresidual basin(1636Ma) and foreland basin (3626Ma(?)). Combined with the basin evolution in the northern QinghaiTibet Plateau during the Cenozoic, this research suggests that an initial collision between the India and the Eurasian plates occurred at the turn of the Cretaceous and the Paleogene before the 56.5Ma, and further underwent three periods, i.e., the first collision (early than 565 Ma), then main collision (565450 Ma) and pulsation intracontinental convergence (4526 Ma ) finally. However, 450 Ma is the most important moment of tectonic transformation. Uplifting of the QinghaiTibet Plateau from the Paleogene to the Neogene was achieved in the successional periods. First, early than 565450 Ma; second, 3016 Ma; third,1636 Ma; and finally, 3626(?) Ma.The Qiangtang block had reached a considerable height as a result of sustained uplifting during the period from 30 to 16 Ma .

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    Sedimentary evolution and palaeogeography of
    the Early Cretaceous basins from the northern Qilian Mountains to Jiuxi areas.
    2011, 18(4): 77-87. 
    Abstract ( 1736 )   PDF (7614KB) ( 931 )  

    Researches on the sediments, paleocurrents and depositional environments of the Early Cretaceous in northern QilianJiuxi areas show that an extensive basin (Northern QinlianJiuquan Lake), covering areas from the midQinlian Mountains in the south to the Beishan in the north and from the western Altyn Fault to Jiudong in the east, existed in the Early Cretaceous. Current study indicates that the Northern QinlianJiuquan Lake was involved in a sedimentary and palaeogeographical evolutionary history in succession, i.e., from initial alluvial fan, and then fluvial, followed by lacustrine and fluvial environment finally. Depositional succession consisting of sediments in a varied grain size from coarser, fine to coarser vertically was a result of the initial, increasing and maximum extension of the Northern QinlianJiuquan Lake. In addition, research suggests that Changma, Hanxia and Hongliuxia areas of the southern basin became the centers of subsidence and deposition resulting from strikeslip of Altyn Fault in the Early Cretaceous, and furthermore the basin extended to the maximum in space as a result.

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    Stratigraphy, sedimentology and tectonic background of basin evolution of the Late JurassicEarly Cretaceous Tuchengzi Formation in YinshanYanshan, North China.
    2011, 18(4): 88-106. 
    Abstract ( 2157 )   PDF (9442KB) ( 883 )  

    The Tuchengzi Formation is the most widely distributed deposits of the Late Jurassic to the Early Cretaceous in YinshanYanshan in North China, which contains a lot of information on paleoclimate, paleogeography, basin and tectonic evolution. Vast distribution and a variety of sediments of the Tuchengzi Formation, however, restrain the interpretations of basin nature and tectonic background, and there are plenty of controversies about the Tuchengzi Formation as well. This paper has briefly reviewed those previous studies of the Tuchengzi Formation in YinshanYanshan. Furthermore, on the basis of geological survey, the paper focuses on the stratigraphy, sedimentary facies, provenances and paleocurrents of the Tuchengzi Formation. Current study indicates that the Tuchengzi Formation was involved in an evolution of sedimentary facies in spacetime, from alluvial fan to delta, lacustrine and river or alluvial fan in ascending order. Palaeo depositional centres of the Tuchengzi Formation were recognized to be located in BaotouHuhehaote of Inner Monggolia, Yanqing of Beijing and Lingyuan of western Liaoning Province respectively, which are related to the distribution of paleocurrents and prove the existence of a giant lacustrine basin in YinshanYanshan, extending from Daqingshan, Northern Hebei and Western Liaoning Province in the Late JurassicEarly Cretaceous. Provenances analysis of conglomerates in the Tuchengzi Formation shows obvious zonations. Pebbles of volcanic and sedimentary rocks are mainly in Western Liaoning Province; pebbles of volcanic rocks and some granite and limestone dominate Northern Hebei Province; and pebbles of metamorphic rocks are chiefly in Daqingshan. In term of regional distribution of basements of the Tuchengzi Formation, provenances of this formation display a good concordance with diverse basements of the Tuchengzi Formation in YinshanYanshan, and furthermore suggest that the Tuchengzi Formation were deposited by an erosion of basements in descending order. The widely distributed large scale platetrough crossbeddings within the top part of the Tuchegnzi Formation in Western Liaoning Province and Hebei Province are interpreted as aeolian deposits resulting from basin's basement uplift of the Tuchengzi Formation. Metamorphic core complex in YinshanYanshan or nearby areas in the Late JurassicEarly Cretaceous previously reported suggests an extensional tectonic background at that time, and it is probable that the coupling of lithospheric thinning was impacted mainly by Pacific plate subduction northwestward in the Late JurassicEarly Cretaceous. This research suggests that the Tuchengzi Formation is the sediments of rift basin and deposited in an extensional tectonic background of the Late JurassicEarly Cretaceous. A new dynamic model of the evolution of basins of Tuchengzi Formation was proposed finally.

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     The example of CosmosEarth System responses: The supercyclic sequence and rhythms of the Wumishan Subsystem of Jixian System.
    2011, 18(4): 107-122. 
    Abstract ( 2387 )   PDF (26303KB) ( 2275 )  

    Yanliao aulacogen is a typical sedimentary basin with global correlation implications of carbonate deposition. It is proposed the establishment of Wumishan Subsystem and series in this paper. And the Wumishan Supercycle of the Middle Proterozoic Jixian (MPSS Ⅱ) is a reef sedimentary supercycle with a huge sediment thickness formed by the balance compensation in the aulacogen basin evolution. Varieties of stromatolites well developed constitute a series of distinct sedimentary rhythms being indicative of a diverse of sedimentary environments, and suggest the rhythm of Milankovitch cycles, asteroid cloud cycles and the galactic plane cycles in the CosmicEarth System. Uplifting of the Shanhaiguan uplift resulted in the formation of a diverse order of sedimentary sequences of siliceous depositions derived from hot watersiliceous sediments and input of red source. Current study indicates that the Wumishan Supercycle be driven by the CosmicEarth System, which further improves our understanding of sedimentary responses to depositional rhythmic variations. Scientific exploration and practice has proved that only by establishing the concept of the universe of Earth Sciences, Earth Science research in order to continue to develop a new vision.

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    The paleoweathering mantle of the Proterozoic rapakivi granite in Miyun County, Beijing and the relationship with the Changzhougou Formation of Changchengian System.
    2011, 18(4): 123-130. 
    Abstract ( 1720 )   PDF (2994KB) ( 1903 )  

    The Changchengian System, with its basal boundary being a key to the delimitation between the Paleo and the MesoProterozoic in the North China Platform, serves actually as an absorbing Proterozoic research field in Chinese geological circle. For a long time it has been difficult to precisely delimit the intraProterozoic ages of North China and their global stratigraphic correlations has been controversial because of lack of available rocks or bodies for age dating. In resent years, the Proterozoic rapakivi granites (dike) with the paleoweathered mantleclastic rocks covered directly by the sandstones of the Changzhougou Formation of Changchengian System are discovered in the Miyun County, Beijing. The detrital components embrace the insitu weathered rocks of rapakivi granites in the lower and the rapakivilike coarsegrained clastic rocks in the upper. Using SHRIMP and LAICPMS dating methods, we have obtained the UPb dating ages of 1682±20 Ma and 1708±5.6 Ma from the detrital zircons sampled in the rocks; those age data are the same with the nearby Miyun Rapakivi Granite. Preliminary analysis has revealed that the Miyun Rapakivi Granite and its synchronic dikes had once been uplifted and outcropped in the air after they were emplaced. The processes of weathering and denudation resulted in both the saprolites and the almost insitu accumulated rapakivi debris. The formation of the weathered rocks was to be preChangzhougou time in age. The existence of this suite of weathered rocks and clastic rocks, and the analysis of the dating results, have shown that the age of the base of the Changzhougou Formation (which belongs to the Changchengian System) should be younger than 1682 Ma instead of the formerly reported 1800 Ma. According to the analysis of the dating results of the insitu rapakivisourced sedimentary clastics and the correlative age data, we here propose a new age of the lower limit of the Changchengian System to be about 16651670 Ma in North China.

     

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    Research on standardization of continental sequence stratigraphy and palaeogeography:A case study from the Upper Triassic Xujiahe Formation in Sichuan Basin.
    2011, 18(4): 131-143. 
    Abstract ( 2664 )   PDF (13658KB) ( 2996 )  

    Standardization is important for the future research on sequence stratigraphy. The framework includes genetic modeling, establishing standardization and application of industrialization. The workflow emphasizes defining the genetic type of sedimentation and the bounding surfaces. Because of the complexity of continental sedimentation in China, gammaray apparatus, element capture device, GPR, element geochemistry and other methods could be used in the research on highresolution sequence classification, establishment of the sequence stratigraphic framework of outcropwellseismic, and identification of thirdorder bounding surfaces and flooding surfaces. The integrated research on highresolution sequence stratigraphy depended on quantitative expression of palaeobathymetry, paleoclimate and geochemistry in sedimentary cycles of continental lake basin. Using the technique in the sequencelithofacies paleographic research of the upper Triassic Xujiahe Formation in Sichuan Basin, the Xujiahe Formation could be divided into five thirdorder sequences. The second member of Xujiahe Formation was part of different system tracts with rising and falling basal level of two thirdorder sequences. The lower part of second member was defined as progressive delta and the upper part was regressive. The thickness and physical property of lower part reservoir is better, and pay formation is mainly in lower part, which is due to the different development mechanism of delta sandstones. Based on sequencepaleogeographic research, the second, fourth, and sixth member of the Xujiahe Formation are defined to be the main reservoir, and the interbedded mudstones could be the source rock. The first, third, and fifth member of the Xujiahe Formation are defined to be the main source rocks; the delta sandstone with lesser scale along basin margin is a significant reservoir too.

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     The sequence stratigraphic response to the basinorogene coupling process of CretaceousNeogene in Tarim Basin, China.
    2011, 18(4): 144-157. 
    Abstract ( 2249 )   PDF (8754KB) ( 958 )  

    On the basis of the comprehensive analyses of the depositional sequence of the CretaceousNeogene outcrop sections, and the seismic sequence and drillhole information in Tarim Basin, the authors hold that the CretaceousNeogene strata can be divided into 32 depositional sequences in the southwestern depression and 27 depositional sequences in the northwestern depression. According to the study of ordered stacking of several 3rdorder sequences and tectonic sequences, 4 tectonic sequence interfacies with the form of unconformity can be identified in Tarim Basin. And the CretaceousNeogene strata may be redivided into 4 supersequences(SS14) which can be correlated synchronously in Tarim Basin, and the supersequence stratigraphic framework of the CretaceousNeogene in Tarim Basin can be established. Each supersequence represented the evolution cycle from progradation to retrogradation of 3rdorder sequence group and possesses the different characteristics of sequence association in different directions. The analysis of tectonic subsidence and depositional provenances indicate that the processes of subsidence and deposition in the depression in front of Tianshan and Kunlunshan Mts. possess the characteristics of subsection and double provenances of foreland basin: Middle subsidence in the Early Cretaceous, slow subsidence in the Late Cretaceous and rapid subsidence in the Paleogence and Neogence. The change of the provenance areas is recycled orogeninner cratonrecycled orogen. And at the same time, the subarea occurred in terms of sequence constitution, depositional speed and depositional system collocation along the orogen due to the difference in the impact of tectonic movements to the provenance area, which was stronger in the western area than in the east. This proves the characteristics of the basinorogene coupling evolution between the depositional filling of southwestern depression and northwestern depression and liftingfall process of Tianshan and Kunlunshan orogens.

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    Magnetostratigraphy of the red soil sequences in southern China: Recent developments.
    2011, 18(4): 158-170. 
    Abstract ( 1610 )   PDF (3645KB) ( 878 )  

    The red soil is the most widely distributed Quaternary deposit in China, which contains a wealth of information on paleoclimate, paleogeography, and hominin evolution. However, because of the climatic conditions of high precipitation and warm temperature, which reduce the preservation of mammalian fossils and other dating materials, it is difficult to obtain precise stratigraphic ages in the red soil area. Magnetostratigraphy is a successful tool for dating both marine and terrestrial sediments. A series of magnetostratigraphic studies has been successfully conducted on the red soil sequences. This paper reviews magnetostratigraphic studies of the red soil sequences in southern China, some of which bear artifact stone tools. The red soils contain four magnetic minerals of goethite, maghemite, magnetite and hematite. Magnetite and hematite were identified as the main carriers of the characteristic remnant magnetizations. Paleomagnetic findings suggest that the red soil sequences in southern China span a period from the late Matuyama reverse chron to the earlymiddle Brunhes normal chron, and that the sequences began to accumulate no later than the Jaramillo age (that is, ca. 11 Ma). The magnetostratigraphies have significantly refined the chronology of the terrestrial red soil sequences in subtropical southern China, thus providing a robust chronological framework for deciphering Quaternary paleoenvironmental processes and probing early human evolution in subtropical eastern Old World.

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    Distinguishing features and their genetic interpretation of stratigraphic sequences in continental deep water setting:A case from Qingshankou Formation in Songliao Basin.
    2011, 18(4): 171-180. 
    Abstract ( 2564 )   PDF (4327KB) ( 1159 )  

    Oil shale and darkmudstone are all in favor of developing in the deep water basins. Studies of deep water sequence stratigraphy belong to one aspect of the essential work for energy exploration and development. Because sediments in deep water were mostly dark mudstone, it is difficult to identify multiscale stratigraphic sequences precisely. Here we performed detailed study of three complete drilling cores from Songliao Basin. There are several significant features corresponding to the boundaries of parasequences. The observed features are bottoms of oil shale beds and organismenriched layers; abrupt increase in TOC, oil yield, hydrocarbongeneration potential and hydrogen index; abrupt decrease in density of sediments; and notch of gamma logging. According to the four division framework for stratigraphic sequences, the abundance of organic matter in lowstand systems tract (LST), transgressive systems tract (TST), highstand system tract, and regressive systems tract (RST), exhibits the trend of lowincreasingmaximum valuedecreasing correspondingly. Considering the fact that the changes of organism content from the edge to the center of the basin are synchronized, we pointed out that the comparison of vertical changes of organism content is an important method for dividing stratigraphic sequences in deep water setting. Through the analysis of organism types and provenance when the baselevel of the lake was high, it is suggested that the mudstone was formed with abundant organism in deep water and the organism was originated within the lake. When the lake baselevel went down, organism in sediments decreased and terrestrial organism was playing a significant role. These results can be also applied to sequence stratigraphic studies in marine deep water environment.

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    The research status and advances in porosity evolution and diagenesis of deep carbonate reservoir.
    2011, 18(4): 181-192. 
    Abstract ( 2119 )   PDF (3241KB) ( 2179 )  

    With the progress of theory and technology and the growth of demand for the gas and oil resources,deep carbonate oil and gas reservoir is becoming the important substitute area for exploration of the oil and gas basins. The research of deep petroleum exploration is focusing on the mechanism of carbonates reservoir property evolution. This thesis systematically summarizes the latest research progress and examples in the deep oil and gas fields both in China and abroad. It expounds the key scientific issues of formation and distribution of high quality carbonates reservoirs, such as changes in porosity with depth, change in porosity associated with dolomitization, fluidrock interactions, porosity related to tectonic activities and basin hydrology, etc.

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    Hydrocarbon potential of the southern margin of North China continent based on reservoir model of the AppalachianhianOuachita Overthrust belts.
    Liang Chuanmao
    2011, 18(4): 193-200. 
    Abstract ( 1922 )   PDF (1288KB) ( 934 )  

    阿巴拉契亚—阿钦塔造山带是北美乃至世界著名的大陆边缘挤压碰撞推覆造山带,是地质学研究的经典地区之一,也是许多经典地学理论和概念的发源地。其中,对地质学影响最大的当属地槽学说。继20世纪60年代由深海钻探带来地学革命之后,由COCORP实施的地震反射剖面和深钻揭示了该造山带的巨大推覆构造。人们惊奇地发现,在巨大推覆体之下的大陆边缘,广泛分布着古生代浅水碳酸盐岩地层并具有巨大油气潜力。于是很多油气公司调整了这些地区油气勘探的战略部署,很快在推覆体之下早古生代地层中得到油气勘探的突破。其中,威尔伯顿(Wilburton)油气田就是当时美国发现的最大油气田之一,其单井天然气日产量有的超过1亿立方英尺。通过综合对比,笔者认为中国北方大陆南部边缘的大别—秦(岭)祁(连)—昆仑这一东西延伸的造山带与美国阿巴拉契亚—阿钦塔推覆大陆边缘在地层、岩相和盆地构造演化史等诸多方面有着惊人的相似性和可比性,是发生在中国北方巨大大陆南缘的古生代挤压碰撞推覆造山带。在许多大洋深水盆地相推覆体之下的早古生代浅水碳酸盐岩地层也具有良好的油气前景。粗略估算,我国北方大陆边缘推覆体之下早古生代碳酸盐岩地层很可能达几十万km2或更多,这一潜力是不可忽视的。

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    The characteristics of sedimentation and reservoirs of reefbeach gas fields in carbonate platform margins, Northeastern Sichuan Basin.
    2011, 18(4): 201-211. 
    Abstract ( 1956 )   PDF (10599KB) ( 884 )  

    The discovery of several large to mediumscale gas fields, such as Puguang gas field, Yuanba gas field, Longgang field etc., reveals that carbonate reefbeach zones have great petroleum exploration potential in the platform margin of the east and west sides of KaijiangLiangping shelf and the west side of ChengkouExi shelf. Previous exploration has confirmed that the characteristics of gas fields, sedimentation and reservoirs of reefbeach are obviously different in different parts of platform margins. However the regularity of the differences needs to be disclosed by further studies. Based on the study of highresolution sequence stratigraphy, sedimentology and reservoir evaluation, the paper analyzes the differences. Two thirdorder sequences have been identified which are shoaling upward, and all of them are composed of transgressive and highstand system tracts. It reveals that the characteristics of sedimentary facies and reservoirs are obviously different in different parts of platform margin. During the period of Changxing, the palaeogeomorphology of platform margins was similar in west and east sides of KaijiangLiangping shelf. The strata with main aggradational stacking patterns were strongly dolomitized at the top of Changxing Formation in TiechanghePuguangGaofengchang platform margin, which was the characteristics of steep ramp, thin sedimentation of beach and developing reef. And the YuanbaLonggang platform margin was characterized by gentle slope, obvious forest and lateral accretion stacking pattern, development both reef and beach, and stronger dolomitization at the top of reef and beach; porosity reservoir with good physical property was developed. In the period of Feixianguan, the asymmetry of the platform margins was clear. In TiechanghePuguangGaofengchang platform margin, the stacking pattern of stratigraphy was still aggradational, and thick oolitic beach with strong dolomitization was developed, and its porefractured type reservoir with good physical properties was developed in the second member of Feixianguan Formation. The YuanbaLonggang platform margin was developed thin oolitic beach with weak dolomitization in the second member of Feixianguan Formation, and the reservoir was typical of pore reservoir with poor physical property. The PanlongdongJiantianba platform margin grew reef and beach in Changxing Formation, and developed oolitic beach in the second member of Feixianguan Formation, both of them were strongly dolomitized and were easy to form available reservoirs. Through the comprehensive study of the characteristics of sedimentation and reservoir, we conclude that the sedimentation and the distribution of reservoir are obviously controlled by the integrated factors of synsedimentary palaeogeomorphology, dolomitization, faults, and the diagenesis and fluids in the burial period.

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    The source and reservoir system analysis of volcanic rock in depositional basin: Taking Fengcheng Formation of Lower Permian in Wuxia Zhungeer, Xingjiang as an example.
    2011, 18(4): 212-218. 
    Abstract ( 1683 )   PDF (47704KB) ( 706 )  

    By studying the feature of source rock and reservoir nature on Fengcheng Formation of the Lower Permian in Wuxia, it is suggested that, owing to the influence of volcanic action, not only the fractureair hole reservoir can be formed in rhyotaxitic weak alloying rubble tuff near craters, but also higher bearing source rocks, such as dolomitic tuff and tuffaceous dolomite can be generated in crater facies. Because of this kind of source rocks, a petroleum system of two kinds of reservoirs with one source is formed, in which the reservoirs are the selfgenerating and selfpreserving reservoir of mother rock and the horizontal fractureair hole reservoir (the former is more important). Using the geochemistry index, rock type and authigene, the organic facies' correlation with volcanic construction has been emphatically studied. According to the fact that big volcanic rock reservoirs contacting with source rock in short distance have the feature of nearsource reservoirs and of selfgenerating and selfpreserving reservoirs, we propose that the best way to guide the prospect of volcanic rock reservoir is to sum up the distribution regularity of volcanic rock source and reservoir system from different basins and different volcanic rocks and constructions.

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    Geological characteristics of the “sweet spot” of Permian coal bed methane exploitation in the eastern margin of the Ordos Basin.
    2011, 18(4): 219-223. 
    Abstract ( 2116 )   PDF (1773KB) ( 1207 )  

    Lots of Permian coal exploration has been done in the eastern margin of the Ordos Basin. Coal bed methane (CBM) exploration has been lasting for a long time with high exploration level. CBM pilots have gotten good achievements. The Fairway area in San Juan Basin has the highest CBM production called“sweet spot”. The different productivity appears in the different places of above mentioned area, which controlled by many factors. This paper discusses coal seam features, reservoir characteristics, and trap performances in the “sweet spot” of the eastern margin of the Ordos Basin in detail to guide CBM exploitation in other areas in terms of similar geological condition.

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    Controls of sedimentation on reservoir formation in Lower Triassic Feixianguan Formation, northeastern Sichuan Basin.
    2011, 18(4): 224-235. 
    Abstract ( 1889 )   PDF (9236KB) ( 930 )  

    Sedimentation is one of the key controlling factors in the formation of the reef and shoal carbonate reservoirs. This research studied the Lower Triassic Feixianguan shoal reservoir of marginal carbonate platform facies in the Puguang and Yuanba area, northeastern Sichuan Basin. The sedimentation background and its evolution history were studied before the microfacies analyses were conducted. The highfrequency cycles were divided and described based on drilling well data. The controls of stratigraphic sequences on reservoir formation, highfrequency cycles on porosity distribution, relative sea level fluctuation on reservoir heterogeneity, as well as early depositional and diagenetic environment on early porosity formation were discussed.

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    The characteristics of oil sand body in the area of Kelatuo Anticline, the north Kashi depression.
    2011, 18(4): 236-242. 
    Abstract ( 1702 )   PDF (1295KB) ( 770 )  

    The north margin of Kashi Depression is one of the beneficial zones of oil and gas exploration in Southwest Tarim Basin. The Kelatuo Anticline has the most oil gas seepages in north Kashi Depression. Through outcrop description and fine strata section correlation in the east of Kelatuo Anticline, the types of sand body formations and their shapes and distributions and microfacies features were distinguished. The thickness of most sand body is 0115 m and the breadth is 10150 m. The main factors controlling the sand reservoir were analyzed.

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