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1.
《International Geology Review》2012,54(11):1417-1442
ABSTRACTThe Ordos Basin, situated in the western part of the North China Craton, preserves the 150-million-year history of North China Craton disruption. Those sedimentary sources from Late Triassic to early Middle Jurassic are controlled by the southern Qinling orogenic belt and northern Yinshan orogenic belt. The Middle and Late Jurassic deposits are received from south, north, east, and west of the Ordos Basin. The Cretaceous deposits are composed of aeolian deposits, probably derived from the plateau to the east. The Ordos Basin records four stages of volcanism in the Mesozoic–Late Triassic (230–220 Ma), Early Jurassic (176 Ma), Middle Jurassic (161 Ma), and Early Cretaceous (132 Ma). Late Triassic and Early Jurassic tuff develop in the southern part of the Ordos Basin, Middle Jurassic in the northeastern part, while Early Cretaceous volcanic rocks have a banding distribution along the eastern part. Mesozoic tectonic evolution can be divided into five stages according to sedimentary and volcanic records: Late Triassic extension in a N–S direction (230–220 Ma), Late Triassic compression in a N–S direction (220–210 Ma), Late Triassic–Early Jurassic–Middle Jurassic extension in a N–S direction (210–168 Ma), Late Jurassic–Early Cretaceous compression in both N–S and E–W directions (168–136 Ma), and Early Cretaceous extension in a NE–SW direction (136–132 Ma). 相似文献
2.
The Blue Nile Basin, situated in the Northwestern Ethiopian Plateau, contains ∼1400 m thick Mesozoic sedimentary section underlain by Neoproterozoic basement rocks and overlain by Early–Late Oligocene and Quaternary volcanic rocks. This study outlines the stratigraphic and structural evolution of the Blue Nile Basin based on field and remote sensing studies along the Gorge of the Nile. The Blue Nile Basin has evolved in three main phases: (1) pre‐sedimentation phase, include pre‐rift peneplanation of the Neoproterozoic basement rocks, possibly during Palaeozoic time; (2) sedimentation phase from Triassic to Early Cretaceous, including: (a) Triassic–Early Jurassic fluvial sedimentation (Lower Sandstone, ∼300 m thick); (b) Early Jurassic marine transgression (glauconitic sandy mudstone, ∼30 m thick); (c) Early–Middle Jurassic deepening of the basin (Lower Limestone, ∼450 m thick); (d) desiccation of the basin and deposition of Early–Middle Jurassic gypsum; (e) Middle–Late Jurassic marine transgression (Upper Limestone, ∼400 m thick); (f) Late Jurassic–Early Cretaceous basin‐uplift and marine regression (alluvial/fluvial Upper Sandstone, ∼280 m thick); (3) the post‐sedimentation phase, including Early–Late Oligocene eruption of 500–2000 m thick Lower volcanic rocks, related to the Afar Mantle Plume and emplacement of ∼300 m thick Quaternary Upper volcanic rocks. The Mesozoic to Cenozoic units were deposited during extension attributed to Triassic–Cretaceous NE–SW‐directed extension related to the Mesozoic rifting of Gondwana. The Blue Nile Basin was formed as a NW‐trending rift, within which much of the Mesozoic clastic and marine sediments were deposited. This was followed by Late Miocene NW–SE‐directed extension related to the Main Ethiopian Rift that formed NE‐trending faults, affecting Lower volcanic rocks and the upper part of the Mesozoic section. The region was subsequently affected by Quaternary E–W and NNE–SSW‐directed extensions related to oblique opening of the Main Ethiopian Rift and development of E‐trending transverse faults, as well as NE–SW‐directed extension in southern Afar (related to northeastward separation of the Arabian Plate from the African Plate) and E–W‐directed extensions in western Afar (related to the stepping of the Red Sea axis into Afar). These Quaternary stress regimes resulted in the development of N‐, ESE‐ and NW‐trending extensional structures within the Blue Nile Basin. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
3.
Wirote Saengsrichan Thasinee Charoentitirat Assanee Meesook Ken-ichiro Hisada Punya Charusiri 《Gondwana Research》2011,19(1):47-60
The Thung Yai Group extends over a large area of peninsular Thailand, along the eastern margin of the Shan Thai block. Bound by angular unconformities 300 m thick dominantly detritic brackish to non-marine deposits with few intercalated limestone beds between Triassic marine and Tertiary non-marine sediments, represent the Thung Yai Group that comprises four formations: Khlong Min, Lam Thap, Sam Chom, and Phun Phin Formations. In the Ao Luk–Plai Phraya (ALPP) area, the Khlong Min and Lam Thap formations yield marine, brackish-water and non-marine fossil assemblages. These include trace fossils and for the first time in peninsular southern Thailand, the bivalve Parvamussium donaiense Mansuy, 1914. Based on fossil determinations, the Thung Yai Group has a late Early Jurassic to Early Cretaceous age.Our new observations help unravel the tectonic history of Mesozoic Peninsular Thailand. After the complete closure of the Paleotethys in the Late Triassic, renewed inundation, from the late Early Jurassic to the early Middle Jurassic, brought a regime of shallow to open marine and lagoon sedimentation over northwestern, western and southern peninsular Thailand, in the eastern part of Sundaland bordering the Mesotethys to the west. 相似文献
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新的地层和古生物学研究结果表明,措勤盆地在晚古生代一早中生代不存在长达75Ma以上的沉积间断．其中,晚二叠世-晚三叠世诺利期都是海相碳酸盐岩地层,晚三叠世瑞替期-早中侏罗世为陆缘碎屑岩地层．两者之间为角度不整合接触．措勤盆地在晚二叠世-晚三叠世诺利期一直处于海相碳酸盐岩盆地中．晚三叠世瑞替期-早中侏罗世仍然是接受巨厚沉积的低洼地区。从宏观的油气勘探的战略评价角度看．措勤盆地在中二叠世栖霞期-晚三叠世诺利期的海相碳酸盐岩地层具有生油层的性质,上三叠统瑞替阶-中下侏罗统具有盖层的性质,两者之间的角度不整合具有储集层的性质。措勤盆地中二叠统-下侏罗统构成一个油气的有利勘探层系．称为古格层系。 相似文献
6.
西藏措勤盆地的上古生界—下中生界：潜在的油气沉积建造 总被引：2，自引：1，他引：1
新的地层和古生物学研究结果表明,措勤盆地在晚古生代一早中生代不存在长达75Ma以上的沉积间断．其中,晚二叠世-晚三叠世诺利期都是海相碳酸盐岩地层,晚三叠世瑞替期-早中侏罗世为陆缘碎屑岩地层．两者之间为角度不整合接触．措勤盆地在晚二叠世-晚三叠世诺利期一直处于海相碳酸盐岩盆地中．晚三叠世瑞替期-早中侏罗世仍然是接受巨厚沉积的低洼地区。从宏观的油气勘探的战略评价角度看．措勤盆地在中二叠世栖霞期-晚三叠世诺利期的海相碳酸盐岩地层具有生油层的性质,上三叠统瑞替阶-中下侏罗统具有盖层的性质,两者之间的角度不整合具有储集层的性质。措勤盆地中二叠统-下侏罗统构成一个油气的有利勘探层系．称为古格层系。 相似文献
7.
《International Geology Review》2012,54(4):307-316
Stratabound barite and celestite deposits, related mainly to three evaporitic sequences, occur in the Mesozoic Neuquen Retroarc Basin, developed to the east of the Andean Cordillera of western Argentina. This basin is filled with Jurassic and Cretaceous marine to continental sediments that unconformably overlie basement rocks of Paleozoic to Triassic age. Celestite deposits formed by initial precipitation from seawater, with later crystallization during diagenesis and recrystallization related to Eocene intrusive activity. This is supported by evidence of evaporitic associations, textures, and Sr and S-isotope data. The barite deposits were deposited in a near-shore environment and could have formed as a result of interaction between barium absorbed in clay minerals (derived from weathering of basement rocks) and hypersaline seawater. This genetic model is supported by evidence such as the stratabound setting, textures, and Sr and S-isotope data. Carbon and oxygen-isotopic compositions of carbonates, which are interbedded with celestites, are in the range expected for marine carbonates. Lead-isotopic compositions of galenas from bedded and vein barite deposits of Upper Jurassic and Lower Cretaceous ages are consistent with Pb remobilization from a source located at high levels of the upper crust, possibly the basement rocks. 相似文献
8.
This paper reports LA–ICP–MS U–Pb dates and in situ Hf isotope analyses of detrital zircons from the Mesozoic basins in western Shandong, China, with the aim to constrain the depositional ages and provenances of the Mesozoic strata as well as the Mesozoic tectonic evolution of the eastern North China Block (NCB). The Mesozoic strata in western Shandong, from bottom to top, include the Fenghuangshan, Fangzi, Santai and Wennan formations. Most of the analyzed zircon grains exhibit oscillatory growth zoning and have relatively high Th/U ratios (generally 0.2–3.4), suggesting a magmatic origin. Zircons from the Fenghuangshan Formation in the Zhoucun Basin yield six main age populations (2489, 1854, 331, 305, 282, and 247 Ma). Zircons from the Fangzi Formation in the Zhoucun and Mengyin basins yield eight main age populations (2494, 1844, 927, 465, 323, 273, 223, and 159 Ma) and ten main age populations (2498, 1847, 932, 808, 540, 431, 315, 282, 227, and 175 Ma), respectively, whereas zircons from the Santai Formation in the Zhoucun and Mengyin basins yield nine main age populations (2519, 1845, 433, 325, 271, 237, 192, 161, and 146 Ma) and six main age populations (2464, 1845, 853, 277, 191, and 150 Ma), respectively. Five main age populations (2558, 1330, 609, 181, and 136 Ma) are detected for zircons from the Wennan Formation in the Pingyi Basin. Based on the youngest age, together with the contact relationships among formations, we propose that the Fenghuangshan Formation formed in the Early–Middle Triassic, the Fangzi Formation in the Middle–Late Jurassic, the Santai Formation after the Late Jurassic, and the Wennan Formation after the Early Cretaceous. These results, together with previously published data, indicate that: (1) the sediments of the Fenghuangshan Formation were sourced from the Precambrian basement and from late Paleozoic to early Mesozoic igneous rocks in the northern part of the NCB; (2) the sediments of the Fangzi and Santai formations were sourced from the Precambrian basement, late Paleozoic to early Mesozoic igneous rocks in the northern part of the NCB, and the Sulu terrane, as well as from Middle–Late Jurassic igneous rocks in the southeastern part of the NCB; and (3) the Wennan Formation was sourced from the Tongshi intrusive complex, the Sulu terrane, and minor Precambrian basement and Early Cretaceous igneous rocks. The evolution of detrital provenance indicates that in the Early–Middle Triassic, the northern part of the NCB was higher than its interior; during the Late Triassic to Early Jurassic, the eastern NCB was uplifted, resulting in a period of non-deposition; and an important transition from a compressional to an extensional tectonic regime occurred during the Middle–Late Jurassic. The presence of Neoproterozoic and Triassic detrital zircons in the Fangzi Formation sourced from the Sulu terrane suggests that large-scale sinistral strike-slip movement along the Tan-Lu Fault Zone did not occur after the Middle Jurassic (ca. 175 Ma). 相似文献
9.
The purpose of the study is to better understand the relationship between organic matter optical properties and the presence of potentially large oil and gas accumulations in Arctic Canada. The type and thermal maturity of the dispersed organic matter of the Mesozoic formations in the southern Sverdrup Basin, Melville Island, have been studied using organic petrology and Rock-Eval pyrolysis.All types of organic matter are present in the strata of Mesozoic age. Hydrogen-rich liptinite is dominated by alginite (Botryococcus and Tasmanites), dinoflagellate cysts and amorphous fluorescing matrix. Sporinite, cutinite, resinite and liptodetrinite made up the lesser hydrogen-rich exinite. Vitrinite reflectance in Cretaceous sediments ranges from 0.36 to 0.65% Ro; in Jurassic sediments it ranges from 0.40 to 1.0% Ro and in the Triassic from 0.45 to 1.30% Ro, showing an overall increase with depth of burial.Cretaceous sediments of the Deer Bay Formation are thermally immature and contain organic matter of terrestrial origin. The Upper Jurassic shales of the Ringnes Formation contain predominantly organic matter of liptinitic and exinitic origin with a considerable vitrinitic input. At optimum maturation levels, potential source beds of this formation would have a good hydrocarbon-generating potential. The hydrocarbon potential, however, would be limited to the generation of gases due to the leanness of the source rocks. Parts of the Lower Jurassic Jameson Bay Formation are organic-rich and contain a mixed exinitic/vitrinitic organic matter, Botryococcus colonial algae but visible organic matter is dominated by high plant remains (mainly spores). The Schei Point Group shales and siltstones contain organic matter of almost purely marine origin, whereas the predominantly higher plant-derived organic matter found in the Deer Bay, Jameson Bay and partly in the Ringnes formations have higher TOC. Among the Schei Point Group samples, the Cape Richards and Eden Bay members of the Hoyle Bay Formation are richer in TOC (>2.0%) than the Murray Harbour Formation (Cape Caledonia Member). This may reflect differences in the level of maturity or in the depositional environment (more anoxic conditions for the former).Regional variations in the level of thermal maturity of Mesozoic sediments in Sverdrup Basin appear to be a function of burial depth. The Mesozoic formations thicken towards the basin centre (NNE direction), reflecting the general pattern of increasing thermal maturity north of Sabine Peninsula. However, the regional thermal-maturation pattern of the Mesozoic is not solely a reflection of the present-day geothermal gradient, which indicates that anomalous zones of high geothermal gradient may have existed in the past, at least since when the Mesozoic sediments attained maximum burial depth. The contour pattern of the regional variation of maturity at the base of numerous Triassic formations is similar to that of the structural contours of the Sverdrup Basin, indicating that present-day maturation levels are largely controlled by basin subsidence. 相似文献
10.
The thermal maturity and source-rock potential of the Upper Palaeozoic and Mesozoic sediments in the Hecla field, Melville Island, Arctic Canada, have been studied using reflected-light microscopy and Rock-Eval pyrolysis. Approximately 250 polished whole-rock samples were examined and their reflectance (% R0, random) measured. In addition, approximately 100 samples were subjected to Rock-Eval/TOC analyses.Hydrogen-rich organic matter in the Schei Point Group sediments is dominated by alginite (Tasmanales), dinoflagellate cysts with minor amounts of sporinite, cutinite, resinite and liptodetrinite in an amorphous fluorescing matrix. Vitrinite reflectance in Cretaceous sediments ranges from 0.41 to 0.54%; in Jurassic sediments it ranges from 0.43 to 0.64% and in Triassic sediments from 0.50 to 0.65%. The Triassic Schei Point Group calcareous shales and marlstones contain organic matter mainly of marine origin, whereas the predominantly terrestially-derived organic matter present in the Jameson Bay (Lower Jurassic) and in the Upper Jurassic to Lower Cretaceous Deer Bay formations have ower TOC. Only the Ringnes Formation has a TOC content of equivalent to or greater than Schei Point source rocks. Within the Schei Point Group, the Cape Richards and Eden Bay members of the Hoyle Bay Formation are slightly richer in TOC than the Murray Harbour Formation (Cape Caledonia Member). Higher average TOC contents (>3.0%) have been reported in the Cape Richards and Eden Bay members in almost all Hecla drillholes.Variations in the level of thermal maturity of Mesozoic sediments in the Hecla field are a function of burial depth. The stratigraphic succession thickens towards the main Sverdrup Basin depocentre located in a N-NE direction. The pattern of the isoreflectance contours at the top of the Triassic (Barrow Formation) is similar to that of formation boundary lines of the same formations, an indication that present-day maturation levels are largely controlled by basin subsidence. 相似文献
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12.
The Hala’alat Mountains are located at the transition between the West Junggar and the Junggar Basin.In this area,rocks are Carboniferous,with younger strata above them that have been identified through well data and high-resolution 3D seismic profiles.Among these strata,seven unconformities are observed and distributed at the bases of:the Permian Jiamuhe Formation,the Permian Fengcheng Formation,the Triassic Baikouquan Formation,the Jurassic Badaowan Formation,the Jurassic Xishanyao Formation,the Cretaceous Tugulu Group and the Paleogene.On the basis of balanced sections,these unconformities are determined to have been formed by erosion of uplifts or rotated fault blocks primarily during the Mesozoic and Cenozoic.In conjunction with the currently understood tectonic background of the surrounding areas,the following conclusions are proposed:the unconformities at the bases of the Permian Jiamuhe and Fengcheng formations are most likely related to the subduction and closure of the Junggar Ocean during the late Carboniferous-early Permian;the unconformities at the bases of the Triassic Baikouquan and Jurassic Badaowan formations are closely related to the late Permian-Triassic Durbut sinistral slip fault;the unconformities at the bases of the middle Jurassic Xishanyao Formation and Cretaceous Tugulu Group may be related to reactivation of the Durbut dextral slip fault in the late Jurassic-early Cretaceous,and the unconformity that gives rise to the widely observed absence of the upper Cretaceous in the northern Junggar Basin may be closely related to large scale uplift.All of these geological phenomena indicate that the West Junggar was not calm in the Mesozoic and Cenozoic and that it experienced at least four periods of tectonic movement. 相似文献
13.
R. O. Brunnschweiler 《Australian Journal of Earth Sciences》2013,60(1):59-79
Antiquated stratigraphic and tectonic concepts on non‐metamorphic upper Palaeozoic and Mesozoic sequences in eastern Burma are revised. Post‐Silurian of Northern Shan States: The misleading traditional term Plateau Limestone ('Devonian‐Permian') is abandoned. The Devonian part is to be known as Shan Dolomite—with the Eifelian Padaukpin Limestone and the Givetian Wetwin Shale as subordinate member formations—and the disconformable Permian as Tonbo Limestone. Carboniferous formations are absent. Upper Palaeozoic of Karen State: The sequence begins with the fossiliferous Middle to Upper Carboniferous Taungnyo Group resting unconformably on the epimetamorphic Mergui ‘Series’ (probably Silurian) and on older metamorphics. There is no evidence of Devonian rocks. The Permian is represented by widespread, but discontinuous, reef complexes, known as Moulmein Limestone, which rest unconformably on the moderately folded Carboniferous. The earliest beds of the Permian are of the Artinskian Epoch. No Mesozoic sequence is known west of the Dawna Range. Mesozoic of Northern Shan States: Triassic and Jurassic are present, but the Cretaceous is absent. The Bawgyo Group (Upper Triassic and Rhaetic) rests unconformably on the Palaeozoic and consists of the Pangno Evaporites (below) and the Napeng Formation. The Jurassic Namyau Group, consisting of the Tati Limestone (Bathonian‐Callovian) and the Hsipaw Redbeds (Middle to Upper Jurassic) follows unconformably. Origin of folding of Mesozoic: The intense primary folding of the Triassic and Jurassic sequences in the Hsipaw region is due to gravity‐sliding (Gleittektonik) on the Upper Triassic evaporites. Secondary complications were introduced by diapiric displacements which are probably continuing. Neither of these tectonic phases shows a significant causal relationship with the Alpine Orogeny sensu stricto. The latter is at best responsible for minor overprinting, chiefly through broad warping and horst‐and‐graben fracturing of the Shan Dolomite with locally considerable vertical displacements. There are no Alpine fold structures in the region. Geotectonically, it was a well‐consolidated frontal block of the Alpidic hinterland. 相似文献
14.
AbstractThe Jurassic–Cretaceous Great Artesian Basin is the most extensive, and largest volume, sedimentary feature of continental Australia. The source of its mud-dominated Cretaceous infill is attributed largely to contemporary magmatism along the continental margin to the east, but the source of its Jurassic infill, dominated by quartz sandstone, remains unconstrained. This paper investigates the question of a Jurassic sediment source for the northern part of the basin. Jurassic uplift and exhumation of the continental margin crustal sector to the east provided the primary Jurassic sediment source. (U–Th)/He data are presented for zircon and apatite from Pennsylvanian to mid Permian granitoids of the Kennedy Igneous Association distributed within the northern Tasmanides between the Townsville and Cairns regions and for coeval granites of the Urannha batholith from the Mount Carlton district (N Bowen Basin), also within the northern Tasmanides. The data from zircon indicate widespread Jurassic exhumation of a crustal tract located to the east of the northern Great Artesian Basin and largely occupied by rocks of the Tasmanides. Detrital zircon age spectra for samples of the Jurassic Hutton and Blantyre sandstones from the northeastern margin of the Great Artesian Basin show their derivation to be largely from rocks of the northern Tasmanides. In combination, the detrital age spectra and (U–Th)/He data from zircon indicate exhumation owing to uplift generating appreciable physiographic relief along the north Queensland continental margin during the Jurassic, shedding sediment westward into the Great Artesian Basin during its early development. A portion of (U–Th)/He data for zircon are consistent with late Permian–mid Triassic exhumation within the Tasmanides, attributable to the influence of the Hunter--Bowen Orogeny. Evidence of Cretaceous and Paleocene exhumation episodes is also indicated for some samples, mainly by apatite (U–Th)/He analysis, consistent with data previously published from fission track studies. Overall, new data from the present study reveal that the exhumation related to Jurassic regional uplift and the subsequent erosional reworking of the northeast Australian continental margin is critical for the evolution and development of the northern side of the Great Artesian Basin in eastern Australia. Apart from this, another two previously suggested Permian–Triassic and Cretaceous exhumation and uplift episodes along the northeast Australian continental margin are also confirmed by the dataset of this study.
- KEY POINTS
U–Pb detrital zircon ages of sandstone samples from the northeastern Eromanga Basin reveal Paleozoic (480–280 Ma) and Proterozoic (1800–1400 Ma) age clusters.
(U–Th)/He zircon and apatite dating results of granitoids samples from Cairns, Townsville and the Mount Carlton districts are dominated by Jurassic (198–164 Ma) and Permian–Triassic (272–238 Ma) age clusters.
Combination of above two datasets proves the regional uplift-driving Jurassic exhumation episode in the northeast Australian continental is vital for the development of the northern Great Artesian Basin.
15.
羌塘盆地油气勘探前景展望 总被引：4，自引：0，他引：4
羌塘盆地为中生代大型的海相残留型构造盆地。盆地的南北缝合带及中央隆起带,宏观上可视为三条构造活动带,其间所夹持的两个相对稳定的地块,特别是南、北坳陷中部的两个复向斜区,是油气勘探的主攻方向。上三叠统—上侏罗统是盆地内的沉积主体,“两坳夹一隆”的古构造格局控制了沉积和烃源层的发育和展布。生物礁、滩多分布在高隆起周缘的碳酸盐岩台地上,发育于各组段中,但以侏罗系布曲组及索瓦组相对集中。盆地内发育有上三叠统肖茶卡组、中侏罗统布曲组和夏里组以及上侏罗统索瓦组四套主要烃源层,估算盆地的总生烃量为9930.92×108t,远景资源量为52.95×108t,具有雄厚的找油物质基础。盆地内发育了四套生储盖组合,其中以侏罗系(组合Ⅲ)布曲组—夏里组亚组合最好,是盆地主要的勘探目的层。应用多种方法综合研究和评价认为,北羌塘坳陷金星湖—东湖—托纳木地区和南羌塘坳陷比洛错东—土门地区是最有利的含油气远景区。 相似文献
16.
Gas systems in the Kuche Depression of the Tarim Basin: Source rock distributions, generation kinetics and gas accumulation history 总被引：2，自引：0，他引：2
Wenzhi Zhao Shuichang Zhang Feiyu Wang Bernhard Cramer Jianping Chen Yongge Sun Baomin Zhang Mengjun Zhao 《Organic Geochemistry》2005,36(12):1583
Six petroleum source beds have been developed in the Kuche Depression (also known as “Kuqa Depression”) of the Tarim Basin, including three lacustrine source rocks (Middle and Upper Triassic Kelamayi and Huangshanjie formations, and Middle Jurassic Qiakemake Formation) and three coal measures (Upper Triassic Taliqike Formation, Lower Jurassic Yangxia Formation, and Middle Jurassic Kezilenuer Formation). While type I–II organic matter occurs in the Middle Jurassic Qiakemake Formation (J2q), other source beds contain dominantly type III organic matter. Gas generation rates and stable carbon isotopic kinetics of methane generation from representative source rocks collected in the Kuche Depression were measured and calculated using an on-line dry and open pyrolysis system. Combined with hydrocarbon generation history modelling, the formation and evolution processes of the Jurassic–Triassic highly efficient gas kitchens were established. High sedimentation rate in the Neogene and the fast deposition of the Kuche Formation within the Pliocene (5 Ma) in particular have led to the rapid increase in Mesozoic source rock maturity, resulting in significant dry gas generation. The extremely high gas generation rates from source kitchens have apparently expedited the formation of highly efficient gas accumulations in the Kuche Depression. Because different Mesozoic source rocks occur in different structural belts, the presence of both lacustrine and coaly gas kitchens during the Cenozoic time can be identified in the Kuche Depression. As shown by the chemical and stable carbon isotope compositions of the discovered gases, the formation of the giant gas pools in the Kela 2, Dina 2, Yaha and Wucan 1 have involved very different geological processes due to the difference in their gas source kitchens. 相似文献
17.
Exploration in the Hammerfest Basin, southwestern Barents Sea, has proven several petroleum systems and plays with the presence of multiple source rocks of mainly Jurassic and Triassic age. To date several fields and discoveries have been found and are described to mainly contain gaseous hydrocarbons with the presence, in some cases, of an oil leg.Our 3D Hammerfest Basin model shows that the Jurassic Hekkingen Formation and the Triassic Snadd and Kobbe formations reached high maturity levels (gas window) in the western and the northwestern margin. At the same time, this model reproduces the main hydrocarbon accumulations that have been found in the basin. An analysis of the volumetrics and the proportion of oil and gas contributions to each field and discovery, suggests that the gas contribution stems mainly from Triassic source rocks, while the oil phases contain variable proportions from the Jurassic Hekkingen Formation and Triassic source rocks.Gas isotope and maturity related biomarker ratios confirm the maturity trends derived from the basin modelling results. Light hydrocarbons indicate the influence of secondary processes (biodegradation and long distance migration) in the petroleum from the Goliat field and the Tornerose discovery. Age related biomarker ratios such as the ETR (extended tricyclic terpane ratio) and the C28/C29 steranes ratio did not provide a clear separation when evaluating a contribution from Jurassic vs. Triassic source rocks. 相似文献
18.
鄂尔多斯盆地中生界低渗透岩性油藏形成规律综述 总被引：15，自引：0，他引：15
鄂尔多斯盆地中生代为典型的大型内陆坳陷湖盆,含油层系主要为三叠系延长组和侏罗系延安组。长7优质烃源岩为中生界油藏的主要源岩,异常高压为中生界低渗透储层油气大规模运移的主要动力,孔隙性砂体和裂缝系统是中生界石油运移的主要通道,多种输导体系和异常压力的有效组合控制了油藏的展布特征。利用储层成岩流体包裹体、自生伊利石测年和沥青期次等多种方法对成藏期次进行了分析,认为中生界油藏的形成为连续充注一期成藏的特点,成藏期可分为早、中、晚三个阶段,分别对应于早白垩世早期、中期和晚期,主成藏期为早白垩世中期的中期成藏阶段。总结出鄂尔多斯盆地延长组低渗透岩性油藏的形成规律,在长7优质烃源岩欠压实作用和生烃增压共同产生异常高压生的作用下,原油通过互相叠置的相对高渗砂体向上、向下运移,在长4+5、长6、长8形成大规模岩性油藏,并通过微裂缝和前侏罗纪古河输导体系,在长2及侏罗系形成了构造-岩性油藏。 相似文献
19.
YU Yuanjiang ZOU Caineng DONG Dazhong WANG Shejiao LI Jianzhong YANG Hu LI Denghu LI Xinjing WANG Yuman HUANG Jinliang 《《地质学报》英文版》2014,88(2):598-619
The presence of shale gas has been confirmed in almost every marine shale distribution area in North America.Formation conditions of shale gas in China are the most favorable for marine,organic-rich shale as well.But there has been little research focusing on shale gas in Qiangtang Basin,Qinghai-Tibet Plateau,where a lot of Mesozoic marine shale formations developed.Based on the survey results of petroleum geology and comprehensive test analysis data for Qinghai-Tibet Plateau,for the first time,this paper discusses characteristics of sedimentary development,thickness distribution,geochemistry,reservoir and burial depth of organic-rich shale,and geological conditions for shale gas formation in Qiangtang Basin.There are four sets of marine shale strata in Qiangtang Basin including Upper Triassic Xiaochaka Formation （T3x）,Middle Jurassic Buqu Formation （J2b）,Xiali Formation （J2x） and Upper Jurassic Suowa Formation （J3s）,the sedimentary types of which are mainly bathyal-basin facies,open platform-platform margin slope facies,lagoon and tidal-fiat facies,as well as delta facies.By comparing it with the indicators of gas shale in the main U.S.basins,it was found that the four marine shale formations in Qiangtang Basin constitute a multi-layer distribution of organic-rich shale,featuring a high degree of thickness and low abundance of organic matter,high thermal evolution maturity,many kinds of brittle minerals,an equivalent content of quartz and clay minerals,a high content of feldspar and low porosity,which provide basic conditions for an accumulation of shale gas resources.Xiaochaka Formation shale is widely distributed,with big thickness and the best gas generating indicators.It is the main gas source layer.Xiali Formation shale is of intermediate thickness and coverage area,with relatively good gas generating indicators and moderate gas formation potential.Buqu Formation shale and Suowa Formation shale are of relatively large thickness,and covering a small area,with poor gas generating indicators,and limited gas formation potential.The shale gas geological resources and technically recoverable resources were estimated by using geologic analogy method,and the prospective areas and potentially favorable areas for Mesozoic marine shale gas in Qiangtang Basin are forecast and analyzed.It is relatively favorable in a tectonic setting and indication of oil and gas,shale maturity,sedimentary thickness and gypsum-salt beds,and in terms of mineral association for shale gas accumulation.But the challenge lies in overcoming the harsh natural conditions which contributes to great difficulties in ground engineering and exploration,and high exploration costs. 相似文献
20.
《International Geology Review》2012,54(8):661-735
The Longmen Shan region includes, from west to east, the northeastern part of the Tibetan Plateau, the Sichuan Basin, and the eastern part of the eastern Sichuan fold-and-thrust belt. In the northeast, it merges with the Micang Shan, a part of the Qinling Mountains. The Longmen Shan region can be divided into two major tectonic elements: (1) an autochthon/parautochthon, which underlies the easternmost part of the Tibetan Plateau, the Sichuan Basin, and the eastern Sichuan fold-and-thrust belt; and (2) a complex allochthon, which underlies the eastern part of the Tibetan Plateau. The allochthon was emplaced toward the southeast during Late Triassic time, and it and the western part of the autochthon/parautochthon were modified by Cenozoic deformation. The autochthon/parautochthon was formed from the western part of the Yangtze platform and consists of a Proterozoic basement covered by a thin, incomplete succession of Late Proterozoic to Middle Triassic shallow-marine and nonmarine sedimentary rocks interrupted by Permian extension and basic magmatism in the southwest. The platform is bounded by continental margins that formed in Silurian time to the west and in Late Proterozoic time to the north. Within the southwestern part of the platform is the narrow N-trending Kungdian high, a paleogeographic unit that was positive during part of Paleozoic time and whose crest is characterized by nonmarine Upper Triassic rocks unconformably overlying Proterozoic basement. In the western part of the Longmen Shan region, the allochthon is composed mainly of a very thick succession of strongly folded Middle and Upper Triassic Songpan Ganzi flysch. Along the eastern side and at the base of the allochthon, pre-Upper Triassic rocks crop out, forming the only exposures of the western margin of the Yangtze platform. Here, Upper Proterozoic to Ordovician, mainly shallow-marine rocks unconformably overlie Yangtze-type Proterozic basement rocks, but in Silurian time a thick section of fine-grained clastic and carbonate rocks were deposited, marking the initial subsidence of the western Yangtze platform and formation of a continental margin. Similar deep-water rocks were deposited throughout Devonian to Middle Triassic time, when Songpan Ganzi flysch deposition began. Permian conglomerate and basic volcanic rocks in the southeastern part of the allochthon indicate a second period of extension along the continental margin. Evidence suggests that the deep-water region along and west of the Yangtze continental margin was underlain mostly by thin continental crust, but its westernmost part may have contained areas underlain by oceanic crust. In the northern part of the Longmen Shan allochthon, thick Devonian to Upper Triassic shallow-water deposits of the Xue Shan platform are flanked by deep-marine rocks and the platform is interpreted to be a fragment of the Qinling continental margin transported westward during early Mesozoic transpressive tectonism. In the Longmen Shan region, the allochthon, carrying the western part of the Yangtze continental margin and Songpan Ganzi flysch, was emplaced to the southeast above rocks of the Yangtze platform autochthon. The eastern margin of the allochthon in the northern Longmen Shan is unconformably overlapped by both Lower and Middle Jurassic strata that are continuous with rocks of the autochthon. Folded rocks of the allochthon are unconformably overlapped by Lower and Middle Jurassic rocks in rare outcrops in the northern part of the region. They also are extensively intruded by a poorly dated, generally undeformed belt, of plutons whose ages (mostly K/Ar ages) range from Late Triassic to early Cenozoic, but most of the reliable ages are early Mesozoic. All evidence indicates that the major deformation within the allochthon is Late Triassic/Early Jurassic in age (Indosinian). The eastern front of the allochthon trends southwest across the present mountain front, so it lies along the mountain front in the northeast, but is located well to the west of the present mountain front on the south. The Late Triassic deformation is characterized by upright to overturned folded and refolded Triassic flysch, with generally NW-trending axial traces in the western part of the region. Folds and thrust faults curve to the north when traced to the east, so that along the eastern front of the allochthon structures trend northeast, involve pre-Triassic rocks, and parallel the eastern boundary of the allochthon. The curvature of structural trends is interpreted as forming part of a left-lateral transpressive boundary developed during emplacement of the allochthon. Regionally, the Longmen Shan lies along a NE-trending transpressive margin of the Yangtze platform within a broad zone of generally N-S shortening. North of the Longmen Shan region, northward subduction led to collision of the South and North China continental fragments along the Qinling Mountains, but northwest of the Longmen Shan region, subduction led to shortening within the Songpan Ganzi flysch basin, forming a detached fold-and-thrust belt. South of the Longmen Shan region, the flysch basin is bounded by the Shaluli Shan/Chola Shan arc—an originally Sfacing arc that reversed polarity in Late Triassic time, leading to shortening along the southern margin of the Songpan Ganzi flysch belt. Shortening within the flysch belt was oblique to the Yangtze continental margin such that the allochthon in the Longmen Shan region was emplaced within a left-lateral transpressive environment. Possible clockwise rotation of the Yangtze platform (part of the South China continental fragment) also may have contributed to left-lateral transpression with SE-directed shortening. During left-lateral transpression, the Xue Shan platform was displaced southwestward from the Qinling orogen and incorporated into the Longmen Shan allochthon. Westward movement of the platform caused complex refolding in the northern part of the Longmen Shan region. Emplacement of the allochthon flexurally loaded the western part of the Yangtze platform autochthon, forming a Late Triassic foredeep. Foredeep deposition, often involving thick conglomerate units derived from the west, continued from Middle Jurassic into Cretaceous time, although evidence for deformation of this age in the allochthon is generally lacking. Folding in the eastern Sichuan fold-and-thrust belt along the eastern side of the Sichuan Basin can be dated as Late Jurassic or Early Cretaceous in age, but only in areas 100 km east of the westernmost folds. Folding and thrusting was related to convergent activity far to the east along the eastern margin of South China. The westernmost folds trend southwest and merge to the south with folds and locally form refolded folds that involve Upper Cretaceous and lower Cenozoic rocks. The boundary between Cenozoic and late Mesozoic folding on the eastern and southern margins of the Sichuan Basin remains poorly determined. The present mountainous eastern margin of the Tibetan Plateau in the Longmen Shan region is a consequence of Cenozoic deformation. It rises within 100 km from 500–600 m in the Sichuan Basin to peaks in the west reaching 5500 m and 7500 m in the north and south, respectively. West of these high peaks is the eastern part of the Tibetan Plateau, an area of low relief at an elevations of about 4000 m. Cenozoic deformation can be demonstrated in the autochthon of the southern Longmen Shan, where the stratigraphic sequence is without an angular unconformity from Paleozoic to Eocene or Oligocene time. During Cenozoic deformation, the western part of the Yangtze platform (part of the autochthon for Late Triassic deformation) was deformed into a N- to NE-trending foldandthrust belt. In its eastern part the fold-thrust belt is detached near the base of the platform succession and affects rocks within and along the western and southern margin of the Sichuan Basin, but to the west and south the detachment is within Proterozoic basement rocks. The westernmost structures of the fold-thrust belt form a belt of exposed basement massifs. During the middle and later part of the Cenozoic deformation, strike-slip faulting became important; the fold-thrust belt became partly right-lateral transpressive in the central and northeastern Longmen Shan. The southern part of the fold-thrust belt has a more complex evolution. Early Nto NE-trending folds and thrust faults are deformed by NW-trending basementinvolved folds and thrust faults that intersect with the NE-trending right-lateral strike-slip faults. Youngest structures in this southern area are dominated by left-lateral transpression related to movement on the Xianshuihe fault system. The extent of Cenozoic deformation within the area underlain by the early Mesozoic allochthon remains unknown, because of the absence of rocks of the appropriate age to date Cenozoic deformation. Klippen of the allochthon were emplaced above the Cenozoic fold-andthrust belt in the central part of the eastern Longmen Shan, indicating that the allochthon was at least partly reactivated during Cenozoic time. Only in the Min Shan in the northern part of the allochthon is Cenozoic deformation demonstrated along two active zones of E-W shortening and associated left-slip. These structures trend obliquely across early Mesozoic structures and are probably related to shortening transferred from a major zone of active left-slip faulting that trends through the western Qinling Mountains. Active deformation is along the left-slip transpressive NW-trending Xianshuihe fault zone in the south, right-slip transpression along several major NE-trending faults in the central and northeastern Longmen Shan, and E-W shortening with minor left-slip movement along the Min Jiang and Huya fault zones in the north. Our estimates of Cenozoic shortening along the eastern margin of the Tibetan Plateau appear to be inadequate to account for the thick crust and high elevation of the plateau. We suggest here that the thick crust and high elevation is caused by lateral flow of the middle and lower crust eastward from the central part of the plateau and only minor crustal shortening in the upper crust. Upper crustal structure is largely controlled in the Longmen Shan region by older crustal anisotropics; thus shortening and eastward movement of upper crustal material is characterized by irregular deformation localized along older structural boundaries. 相似文献