2008 Vol. 26, No. 4
Display Method:
2008, 26(4): 541-551.
Abstract:
The basic tectonostratum pattern of Kunlun Orogenic Belt, which was the product of oceancontinent transformation and collisional orogeny during Early Paleozoic and Late Paleozoic, was developed on the basis of Paleozoic. The Caledonian collisional orogeny, at the end of Early Paleozoic, made the Early Paleozoic ocean basin close and the whole Kulun area was uplifted to be land. As a sedimentary response to orogeny, the sediments of EarlyMiddle Devonian foreland basin formed at the piedmont area within the suture zone. The EarlyMiddle Devonian of East Kunlun mainly distributes in Middle Kunlun and Southern Kunlun. The northern part has sediments formed in the environment of abyssalbathyal basin, shallow sea shelf and sealand transition facies while the southern part is littoralneritic. The sediments are characterised by wedge shape which becomes thinner from north to south in 3D space. They display characteristics that the environment once changed from abyssalbathyal to shallow sea shelf finally to sealand alternation facies in temporal sequence, which reflect that the basin became shallower upward. The material sources were mainly from the northern part, namely the Early Paleozoic Orogenic Belt of Northern Kunlun, the southern part was secondary source area. Because the sediments developed on the subduction landmass, at the end of Silurian when Qimantage ocean basin had closed, they reflect that they have peripheral foreland basin sedimentary characteristics. In West Kunlun, the Middle Devonian only developed in the northern part, while the southwest was mainly abyssalbathyal basin sediments and the upper developed littoralneritic sediments, the northern part and the southern margin of Tarim basin developed littoralneritic sediments. These sediments are wedgeshaped in 3D space becoming thinner from southwest to northeast. In temporal sequence, their sedimentary environment changed from abyssalbathyal to shallow sea to sealand alternation finally to land facies. They also reflect that the basin became shallower upward. The material sources were mainly from southwest orogenic belt, while the Tarim ancient land in the northeast was secondary source area. Considered that the strata developed in the northern part of Middle Kunlun magmatic backarc, at the end of Ordovician when Kudi ocean basin had closed, it can be concluded that the sedimentary environment is backarc foreland.
The basic tectonostratum pattern of Kunlun Orogenic Belt, which was the product of oceancontinent transformation and collisional orogeny during Early Paleozoic and Late Paleozoic, was developed on the basis of Paleozoic. The Caledonian collisional orogeny, at the end of Early Paleozoic, made the Early Paleozoic ocean basin close and the whole Kulun area was uplifted to be land. As a sedimentary response to orogeny, the sediments of EarlyMiddle Devonian foreland basin formed at the piedmont area within the suture zone. The EarlyMiddle Devonian of East Kunlun mainly distributes in Middle Kunlun and Southern Kunlun. The northern part has sediments formed in the environment of abyssalbathyal basin, shallow sea shelf and sealand transition facies while the southern part is littoralneritic. The sediments are characterised by wedge shape which becomes thinner from north to south in 3D space. They display characteristics that the environment once changed from abyssalbathyal to shallow sea shelf finally to sealand alternation facies in temporal sequence, which reflect that the basin became shallower upward. The material sources were mainly from the northern part, namely the Early Paleozoic Orogenic Belt of Northern Kunlun, the southern part was secondary source area. Because the sediments developed on the subduction landmass, at the end of Silurian when Qimantage ocean basin had closed, they reflect that they have peripheral foreland basin sedimentary characteristics. In West Kunlun, the Middle Devonian only developed in the northern part, while the southwest was mainly abyssalbathyal basin sediments and the upper developed littoralneritic sediments, the northern part and the southern margin of Tarim basin developed littoralneritic sediments. These sediments are wedgeshaped in 3D space becoming thinner from southwest to northeast. In temporal sequence, their sedimentary environment changed from abyssalbathyal to shallow sea to sealand alternation finally to land facies. They also reflect that the basin became shallower upward. The material sources were mainly from southwest orogenic belt, while the Tarim ancient land in the northeast was secondary source area. Considered that the strata developed in the northern part of Middle Kunlun magmatic backarc, at the end of Ordovician when Kudi ocean basin had closed, it can be concluded that the sedimentary environment is backarc foreland.
2008, 26(4): 559-564.
Abstract:
Mugagangri Groups is a suite of flyschflyschoid elastic deposits, and is EarlyMiddle Jurassic abyssal sedimentary, which is widespread in the western side of the Bangong CoNujiang junction zone. The paper debates the sequence of sedimentation, tectonicstratigraphic environment of renewestablishment Mugagangri Groups and its geological significance on the basis of the regional geological survey of 1∶〖KG-*2〗250 000 Rutog Sheet. The Mugagangri Groups was divided into two formations according to the features of sedimentary formations, rock associations, paleogeography and fossil aspects; it is advisable to separate it from the original Mugagar Kangri stratigraphic area.
Mugagangri Groups is a suite of flyschflyschoid elastic deposits, and is EarlyMiddle Jurassic abyssal sedimentary, which is widespread in the western side of the Bangong CoNujiang junction zone. The paper debates the sequence of sedimentation, tectonicstratigraphic environment of renewestablishment Mugagangri Groups and its geological significance on the basis of the regional geological survey of 1∶〖KG-*2〗250 000 Rutog Sheet. The Mugagangri Groups was divided into two formations according to the features of sedimentary formations, rock associations, paleogeography and fossil aspects; it is advisable to separate it from the original Mugagar Kangri stratigraphic area.
2008, 26(4): 565-574.
Abstract:
In the long Precambrian, the stromatolitic carbonate succession is very common. But, the nonstromatolitic carbonate succession that is marked by the subtidal deposits forms a strong contrast to the stromatolitic carbonate succession. Both the nonstromatolitic and the stromatolitic carbonate successions are important clues for the further understanding of the evolving carbonate world of the Precambrian. The Mesoproterozoic Gaoyuzhuang Fm. in Yanshan Area is a set of more than 1000mthick carbonate strata that can be divided into four Members (or Subformations): The first Member (or the Guandi Subformation) is marked by a set of stromatolitic dolomites overlying a set of transgressive sandstones; The second Member (or the Sangshuan Subformation) is a set of manganiferous dolomites with a few stromatolites; The third Member is chiefly made up of limestones and is characterized by a particularly nonstromatolitic carbonate succession of the Precambrian; The fourth Member (or the Huanxiusi Subformation) is composed of a set of dolomites of stromatolitic reefs or lithoherms. The nonstromatolitic carbonate succession making up the third Member of the Gaoyuzhuang Formation at the Qiangou section in Yanqing County of Beijing can further be subdivided into three thirdorder sequences that are marked by the regular succession of sedimentary facies. In thirdorder sequences, lots of subtidal carbonate meterscale cycles made up of the midiumbedded leiolite limestones and the thinbedded marls constitute their transgressive system tracts (TSTs) and the early highstand system tracts (EHSTs), lots of meterscale cycles made up by the thinbedded limestones and marls constitute their condensed sections (CSs), and thickbedded to massive dolimitic limestones or lime dolomites make up the late highstand system tracts (LHSTs). The time scan of the Gaoyuzhuang Formation is deduced as 200 Ma (from 1600 Ma to 1400 Ma). An obvious hiatus between the Gaoyuzhuang Formation and the underlying Dahongyu Formation is deduced as 50 Ma to 100 Ma, so the forming duration of the Gaoyuzhuang Formation is thought as the 100 Ma (1 500 Ma to 1 400 Ma). Furthermore, the subface of the third Member of the Gaoyuzhuang Formation that is just on the mid position of the Gaoyuzhuang Formation and its forming age may be deduced as about 1 450 Ma. According to these materials, the nonstromatolitic sedimentary succession make up the third Member of the Gaoyuzhuang Formation may demonstrates a stromatolite decline event occurring at ca. 1 450 Ma of the Proterozoic besides other three events that respectively occurred at ca. 2 000 Ma, ca. 1 000 Ma and ca. 675 Ma. The forming duration of this nonstromatolitic sedimentary succession of the third Member of the Gaoyuzhuang Formation can be generally correlative that of a similar sedimentary succession in North America, i.e. a nonstromatolitic sedimentary succession of the Helena Formation of the Belt Supergroup, which suggests that the stromatolite decline occurring at ca. 1 450 Ma is a global event. All of these information’s endow the nonstromatolitic sedimentary succession making up the third Member of the Gaoyuzhuang Formation at the Qiangou section with important significance. The particularly nonstromatolitic carbonate succession make up the third Member of the Mesoproterozoic Gaoyuzhuang Formation at the Qiangou section might be the representative of the nonstromatolitic carbonate succession of the Precambrian because of its special lithological features and particular sedimentary structures, whose general sedimentary features are helpful and meaningful for the further understanding of changing regularities of the sophisticate and evolving carbonate world of the Precambrian.
In the long Precambrian, the stromatolitic carbonate succession is very common. But, the nonstromatolitic carbonate succession that is marked by the subtidal deposits forms a strong contrast to the stromatolitic carbonate succession. Both the nonstromatolitic and the stromatolitic carbonate successions are important clues for the further understanding of the evolving carbonate world of the Precambrian. The Mesoproterozoic Gaoyuzhuang Fm. in Yanshan Area is a set of more than 1000mthick carbonate strata that can be divided into four Members (or Subformations): The first Member (or the Guandi Subformation) is marked by a set of stromatolitic dolomites overlying a set of transgressive sandstones; The second Member (or the Sangshuan Subformation) is a set of manganiferous dolomites with a few stromatolites; The third Member is chiefly made up of limestones and is characterized by a particularly nonstromatolitic carbonate succession of the Precambrian; The fourth Member (or the Huanxiusi Subformation) is composed of a set of dolomites of stromatolitic reefs or lithoherms. The nonstromatolitic carbonate succession making up the third Member of the Gaoyuzhuang Formation at the Qiangou section in Yanqing County of Beijing can further be subdivided into three thirdorder sequences that are marked by the regular succession of sedimentary facies. In thirdorder sequences, lots of subtidal carbonate meterscale cycles made up of the midiumbedded leiolite limestones and the thinbedded marls constitute their transgressive system tracts (TSTs) and the early highstand system tracts (EHSTs), lots of meterscale cycles made up by the thinbedded limestones and marls constitute their condensed sections (CSs), and thickbedded to massive dolimitic limestones or lime dolomites make up the late highstand system tracts (LHSTs). The time scan of the Gaoyuzhuang Formation is deduced as 200 Ma (from 1600 Ma to 1400 Ma). An obvious hiatus between the Gaoyuzhuang Formation and the underlying Dahongyu Formation is deduced as 50 Ma to 100 Ma, so the forming duration of the Gaoyuzhuang Formation is thought as the 100 Ma (1 500 Ma to 1 400 Ma). Furthermore, the subface of the third Member of the Gaoyuzhuang Formation that is just on the mid position of the Gaoyuzhuang Formation and its forming age may be deduced as about 1 450 Ma. According to these materials, the nonstromatolitic sedimentary succession make up the third Member of the Gaoyuzhuang Formation may demonstrates a stromatolite decline event occurring at ca. 1 450 Ma of the Proterozoic besides other three events that respectively occurred at ca. 2 000 Ma, ca. 1 000 Ma and ca. 675 Ma. The forming duration of this nonstromatolitic sedimentary succession of the third Member of the Gaoyuzhuang Formation can be generally correlative that of a similar sedimentary succession in North America, i.e. a nonstromatolitic sedimentary succession of the Helena Formation of the Belt Supergroup, which suggests that the stromatolite decline occurring at ca. 1 450 Ma is a global event. All of these information’s endow the nonstromatolitic sedimentary succession making up the third Member of the Gaoyuzhuang Formation at the Qiangou section with important significance. The particularly nonstromatolitic carbonate succession make up the third Member of the Mesoproterozoic Gaoyuzhuang Formation at the Qiangou section might be the representative of the nonstromatolitic carbonate succession of the Precambrian because of its special lithological features and particular sedimentary structures, whose general sedimentary features are helpful and meaningful for the further understanding of changing regularities of the sophisticate and evolving carbonate world of the Precambrian.
2008, 26(4): 583-592.
Abstract:
In the geological history, the distribution and the development of sedimentary facies was controlled by the regional tectonics and the regional relief. The Luzhou Uplift, which under the influence of Dongwu Movement, was one of the important controlling factors for the distribution of the Mesozoic sedimentary environment and the sedimentary facies in the area of southern Sichuan basin. During the Early and the Middle Triassic, the Luzhou Uplift developed and stretched to the south, the regional topography characteristic influenced the local sedimentary environment change and sealevel controlled the sedimentary facies distribution and the thickness of strata. For example, the Baoyuan and the Longzhao are two gasbearing structures, in which the reservoirs distribute in lower Triassic. Both of these two gasbearing structures are located at the south slope of the Luzhou Uplift, but the position of the Baoyua structure is on the upper part of the slope, and the Longzhao structure is on the lower slope. The position of the Baoyuan structure is higher than that of the Longzhao. At the high slope of the Uplift, the open sea environment had the stronger hydroenergy, the different banks such as oncolite and bioclastic could be deposited in this area. This sedimentary environment is better for reservoirs formation. From the higher part to the lower part of the Luzhou Uplift, along with the depth of water inc
In the geological history, the distribution and the development of sedimentary facies was controlled by the regional tectonics and the regional relief. The Luzhou Uplift, which under the influence of Dongwu Movement, was one of the important controlling factors for the distribution of the Mesozoic sedimentary environment and the sedimentary facies in the area of southern Sichuan basin. During the Early and the Middle Triassic, the Luzhou Uplift developed and stretched to the south, the regional topography characteristic influenced the local sedimentary environment change and sealevel controlled the sedimentary facies distribution and the thickness of strata. For example, the Baoyuan and the Longzhao are two gasbearing structures, in which the reservoirs distribute in lower Triassic. Both of these two gasbearing structures are located at the south slope of the Luzhou Uplift, but the position of the Baoyua structure is on the upper part of the slope, and the Longzhao structure is on the lower slope. The position of the Baoyuan structure is higher than that of the Longzhao. At the high slope of the Uplift, the open sea environment had the stronger hydroenergy, the different banks such as oncolite and bioclastic could be deposited in this area. This sedimentary environment is better for reservoirs formation. From the higher part to the lower part of the Luzhou Uplift, along with the depth of water inc
2008, 26(4): 602-609.
Abstract:
Palaeoproterozoic cherts from Xiong′er Group in the southern part of the North China block formed in sedimentary rock, but a few in volcanic rocks. The distributions of major and trace elements for cherts demonstrate that cherts were affected by both the hydrothermal process and hydrogenous process. The hydrothermal process might be related with Xiong′er Group volcanism, its geochemical characteristics show the lower concentrations of TiO2, MgO, Al2O3, ∑REE , the lower ratio of A1/(A1+Fe+Mn) and U/Th>1, the NASCnormalized flat REE patterns with weak negative Ce anomalies and positive Eu anomalies. The hydrothermal process was less influenced by the input of terrigenous component due to quick subsidence. However, the hydrogenous genesis cherts were which showed LREE enrichment (LaN/YbN=1.41~9.04) and the high ∑REE, influenced by the input of terrigenous component. The lower ratio of Cr/Th, the chondritenormalized REE patterns and primitive mantlenormalized traceelement patterns for cherts are consistent with the volcanic rocks of the Xiong’er suggest that the single provenance. The cherts were mainly derived from the mixture of basalticandesite and daciterhyolite from Xiong′er Group. The characteristics of Al2O3/(Al2O3+Fe2O3), Ce/Ce*(0.77~0.94) and LaN/CeN(1.18~1.47) implied a setting of passive continental margin. The hydrothermal activity is interpreted as having been related to the intensity extensional background in the Xiong′erZhongtiao Aulacogen, as early as the Palaeoproterozoic. According to the geological characteristics and the ratio of elements, such as Sr/Ba, Th/U, CaO/(CaO+MgO), the cherts deposited in both marine and marineterrigenous facies. As a result of transgression toward north, southern part of Henan was in the marine environment, but northern part of Henan was marineterrigenous, some areas still in continent environment.
Palaeoproterozoic cherts from Xiong′er Group in the southern part of the North China block formed in sedimentary rock, but a few in volcanic rocks. The distributions of major and trace elements for cherts demonstrate that cherts were affected by both the hydrothermal process and hydrogenous process. The hydrothermal process might be related with Xiong′er Group volcanism, its geochemical characteristics show the lower concentrations of TiO2, MgO, Al2O3, ∑REE , the lower ratio of A1/(A1+Fe+Mn) and U/Th>1, the NASCnormalized flat REE patterns with weak negative Ce anomalies and positive Eu anomalies. The hydrothermal process was less influenced by the input of terrigenous component due to quick subsidence. However, the hydrogenous genesis cherts were which showed LREE enrichment (LaN/YbN=1.41~9.04) and the high ∑REE, influenced by the input of terrigenous component. The lower ratio of Cr/Th, the chondritenormalized REE patterns and primitive mantlenormalized traceelement patterns for cherts are consistent with the volcanic rocks of the Xiong’er suggest that the single provenance. The cherts were mainly derived from the mixture of basalticandesite and daciterhyolite from Xiong′er Group. The characteristics of Al2O3/(Al2O3+Fe2O3), Ce/Ce*(0.77~0.94) and LaN/CeN(1.18~1.47) implied a setting of passive continental margin. The hydrothermal activity is interpreted as having been related to the intensity extensional background in the Xiong′erZhongtiao Aulacogen, as early as the Palaeoproterozoic. According to the geological characteristics and the ratio of elements, such as Sr/Ba, Th/U, CaO/(CaO+MgO), the cherts deposited in both marine and marineterrigenous facies. As a result of transgression toward north, southern part of Henan was in the marine environment, but northern part of Henan was marineterrigenous, some areas still in continent environment.
2008, 26(4): 624-631.
Abstract:
Based on the theory and technology of Cross′s highresolution sequence stratigraphy, and two longterm, five middleterm and above ten shortterm cyclic sequences from Xiagou Formation of Lower Cretaceous in Qingxi Sag, Jiuquan Basin were classified. The structure types, stacking patterns, distributing mode and development relation to reservoir sand body of shortterm, middleterm, longterm cyclic sequences are analyzed. The sourcereservoirseal associations and the plane distribution rule of ferrodolomitealbite exhalative rock in the chronostratigraghic framework are discussed in detail.
Based on the theory and technology of Cross′s highresolution sequence stratigraphy, and two longterm, five middleterm and above ten shortterm cyclic sequences from Xiagou Formation of Lower Cretaceous in Qingxi Sag, Jiuquan Basin were classified. The structure types, stacking patterns, distributing mode and development relation to reservoir sand body of shortterm, middleterm, longterm cyclic sequences are analyzed. The sourcereservoirseal associations and the plane distribution rule of ferrodolomitealbite exhalative rock in the chronostratigraghic framework are discussed in detail.
2008, 26(4): 640-646.
Abstract:
The origin of extra lowpermeability and controlling factors of Chan
g 6 reservoir in Zhuang 40 area of Xifeng oil field are studied synthetically through using the log information, testing and analytical information such as casting section, scanning electron microscope, Xdiffraction, grain size analysis and mercury penetration, et al. The results show that sedimentation and diagenesis have impacted on the origins of extra lowpermeability together, it is displayed that microfacies influenced properties greater, the properties in the medium of alluvial fan are better than that in the fringe. Meanwhile, grade in another factor caused the origin of extra low permeability, however, the component maturity have not showed obvious influence on the origin of extra low permeability, compaction and cementation decreased the porosity and permeability, denudation and diagenetic microfracture provided favorable conditions for the existence and movement of oil and gas.
The origin of extra lowpermeability and controlling factors of Chan
g 6 reservoir in Zhuang 40 area of Xifeng oil field are studied synthetically through using the log information, testing and analytical information such as casting section, scanning electron microscope, Xdiffraction, grain size analysis and mercury penetration, et al. The results show that sedimentation and diagenesis have impacted on the origins of extra lowpermeability together, it is displayed that microfacies influenced properties greater, the properties in the medium of alluvial fan are better than that in the fringe. Meanwhile, grade in another factor caused the origin of extra low permeability, however, the component maturity have not showed obvious influence on the origin of extra low permeability, compaction and cementation decreased the porosity and permeability, denudation and diagenetic microfracture provided favorable conditions for the existence and movement of oil and gas.
2008, 26(4): 647-654.
Abstract:
Grainsize analysis of BLK1 section, retrieved from Barkol Lake, NW China, was carried out using a Malvern 2000 grainsize analyzer, and environmentally sensitive grainsize components can be easily identified according to the variations in the grainsize standard deviation. The results indicated that 45~170 μm grainsize component and its mean grainsize diameter are sensitive to the regional dust events in the study area, combined with the radiocarbon ages, the dust events during the last 9.4 cal ka BP was reconstructed.
During the last 2 000 years, strong dust events appeared at 240～440 cal aBP, 600～1 280 cal aBP and 1 400～1 800 cal aBP epochs, which are consistent well with the high values of raindust frequency and high contents of ions in Guliya Ice Core. During the last 9.4 cal kaBP, 8 000～8 300 cal aBP, 7 400～77 00 cal aBP, 6 500～7 000 cal aBP, especially during the middle Holocene epoch of 3 900～6 100 cal aBP, the regional dust events took place continually, which can contrast well with the microparticulate records in Guliya and Dunde Ice Cores. Lacustrine sediment in droughty areas is a good carrier which can denote the dust events during the historical period well, as the climatic variations has great regional characteristics, and so the environmentally sensitive grainsize components in some one section could not be used universally.
Grainsize analysis of BLK1 section, retrieved from Barkol Lake, NW China, was carried out using a Malvern 2000 grainsize analyzer, and environmentally sensitive grainsize components can be easily identified according to the variations in the grainsize standard deviation. The results indicated that 45~170 μm grainsize component and its mean grainsize diameter are sensitive to the regional dust events in the study area, combined with the radiocarbon ages, the dust events during the last 9.4 cal ka BP was reconstructed.
During the last 2 000 years, strong dust events appeared at 240～440 cal aBP, 600～1 280 cal aBP and 1 400～1 800 cal aBP epochs, which are consistent well with the high values of raindust frequency and high contents of ions in Guliya Ice Core. During the last 9.4 cal kaBP, 8 000～8 300 cal aBP, 7 400～77 00 cal aBP, 6 500～7 000 cal aBP, especially during the middle Holocene epoch of 3 900～6 100 cal aBP, the regional dust events took place continually, which can contrast well with the microparticulate records in Guliya and Dunde Ice Cores. Lacustrine sediment in droughty areas is a good carrier which can denote the dust events during the historical period well, as the climatic variations has great regional characteristics, and so the environmentally sensitive grainsize components in some one section could not be used universally.
2008, 26(4): 661-669.
Abstract:
The Cruise of Chinese Second Arctic Science Expedition were conducted from July to September 2003, The concentrations of total hydrolyzable amino acids (THAA), hexosamines(HA) in the Chukchi Sea and Canada Basin surface sediment samples were measured. The major compositions were different between areas, in Chukchi Sea, Glutamic acid(Glu), Glycine (Gly) were the major forms of amino acid, while Serine(Ser) took the main part at the Stations B80, B11,P27 in Canada Basin, and features in sediments included total organic carbon(TOC),total nitrogen(TN),THAA,HA ,etc. varied greatly with different areas, TOC, HA were lowest at BS11 and that THAA,TN were lowest at B80; TOC, TN were highest at R03 while R11 had the highest THAA and P11 had the hightest HA. The spatial variation of amino acids in surface sediments of Chukchi SeaCanada Basin was discussed, DI’’ was introduced according to amino acid selective preservation and Principal Component Analysis to investigate the organic matter degradation of the seven stations sediments, by which we sort them as C15>BS11>R11>S11>P11>R03>B80, the sequence was related to sediment sources and hydrographic conditions. This indicated Bering Strait organic matter in sediments was fresher than Chukchi Cape and Canada Basin, between which was Chukchi shelf.
The Cruise of Chinese Second Arctic Science Expedition were conducted from July to September 2003, The concentrations of total hydrolyzable amino acids (THAA), hexosamines(HA) in the Chukchi Sea and Canada Basin surface sediment samples were measured. The major compositions were different between areas, in Chukchi Sea, Glutamic acid(Glu), Glycine (Gly) were the major forms of amino acid, while Serine(Ser) took the main part at the Stations B80, B11,P27 in Canada Basin, and features in sediments included total organic carbon(TOC),total nitrogen(TN),THAA,HA ,etc. varied greatly with different areas, TOC, HA were lowest at BS11 and that THAA,TN were lowest at B80; TOC, TN were highest at R03 while R11 had the highest THAA and P11 had the hightest HA. The spatial variation of amino acids in surface sediments of Chukchi SeaCanada Basin was discussed, DI’’ was introduced according to amino acid selective preservation and Principal Component Analysis to investigate the organic matter degradation of the seven stations sediments, by which we sort them as C15>BS11>R11>S11>P11>R03>B80, the sequence was related to sediment sources and hydrographic conditions. This indicated Bering Strait organic matter in sediments was fresher than Chukchi Cape and Canada Basin, between which was Chukchi shelf.
2008, 26(4): 670-675.
Abstract:
For the research of characteristics of biodiversity of microorganisms from a tufa fan deposition of karst waterfall, the authors conducted out a field work at Horse′s hoof Waterfall in Guizhou from July to September in 2006. After identification and analysis in laboratory, 2５ microorganisms taxa belonging to four groups have been found from this tufa fan deposit at Horse′s hoof Waterfall. Among them, there are one species for cyanobacteria while sixteen for protozoan , one for green algae and seven for diatoms. And six taxa for bryophytes also were found from same tufa fan. The relationship between biodiversity of microorganisms and tufa deposition at activa waterfall have been disscused in this paper.
For the research of characteristics of biodiversity of microorganisms from a tufa fan deposition of karst waterfall, the authors conducted out a field work at Horse′s hoof Waterfall in Guizhou from July to September in 2006. After identification and analysis in laboratory, 2５ microorganisms taxa belonging to four groups have been found from this tufa fan deposit at Horse′s hoof Waterfall. Among them, there are one species for cyanobacteria while sixteen for protozoan , one for green algae and seven for diatoms. And six taxa for bryophytes also were found from same tufa fan. The relationship between biodiversity of microorganisms and tufa deposition at activa waterfall have been disscused in this paper.
2008, 26(4): 683-687.
Abstract:
The study on chromatography mass analysis of saturated hydrocarbons in Paleogene saline formation of Jiyang Depression shows that dinosterane and C31sterane developed in source rocks of the 1st member（Es1）, the 3rd member（Es3）and upper the 4th member（EsU4）of Shahejie Formation, these molecular fossils are marks of marine transgression, moreover C31sterane denotes that the formation is influenced more by sea water, therefore salinity of 3 members related to marine transgression.
The study on chromatography mass analysis of saturated hydrocarbons in Paleogene saline formation of Jiyang Depression shows that dinosterane and C31sterane developed in source rocks of the 1st member（Es1）, the 3rd member（Es3）and upper the 4th member（EsU4）of Shahejie Formation, these molecular fossils are marks of marine transgression, moreover C31sterane denotes that the formation is influenced more by sea water, therefore salinity of 3 members related to marine transgression.
2008, 26(4): 697-704.
Abstract:
Located on the southern margin of the southern Qaingtang depression, the Zaring area is a “gap area” for hydrocarbon investigation. Detailed reconnaissance of 1∶〖KG-*2〗50,000 petroleum geological structures was carried out in the Zaring block of the Qaingtang Basin, and according to the reconnaissance results the authors analyze biomarkers and molecular carbon isotopic composition of oil seepages in this area, and the oil/source correlation was also discussed in this paper. The data indicate that the oilforming matrixes are algae and higher plants, especially with an important contribution of algae to the formation. The crude oils were formed under weak reductionreduction and salt water environment. The crude oils are mature. The biomarkers of crude oils are closely correlated to those of the Xiali Formation hydrocarbon source rocks, reflecting that crude oils were mainly originated from the Xiali Formation. However, compound specific Cisotope composition exists some differences between crude oils and Xiali Formation hydrocarbon source rocks, indicating a mixture of sources.
Located on the southern margin of the southern Qaingtang depression, the Zaring area is a “gap area” for hydrocarbon investigation. Detailed reconnaissance of 1∶〖KG-*2〗50,000 petroleum geological structures was carried out in the Zaring block of the Qaingtang Basin, and according to the reconnaissance results the authors analyze biomarkers and molecular carbon isotopic composition of oil seepages in this area, and the oil/source correlation was also discussed in this paper. The data indicate that the oilforming matrixes are algae and higher plants, especially with an important contribution of algae to the formation. The crude oils were formed under weak reductionreduction and salt water environment. The crude oils are mature. The biomarkers of crude oils are closely correlated to those of the Xiali Formation hydrocarbon source rocks, reflecting that crude oils were mainly originated from the Xiali Formation. However, compound specific Cisotope composition exists some differences between crude oils and Xiali Formation hydrocarbon source rocks, indicating a mixture of sources.
2008, 26(4): 709-714.
Abstract:
The carbon isotopic compositions of the oils and its group components, which collected from the deep marine oil reservoirs in Tabei Uplift of Tarim Basin, were analyzed by the MAT252 Isotope Mass Spectrometer. The results showed that carbon isotopic compositions of these deep oils are mainly controlled by their parent material, and less affected by the thermal effects. Reversely, the carbon isotopic compositions and its reversed distributions and fractionations of these deep oil group components, on the basis of inheriting the carbon isotopic composition of parent materials, are evidently affected by the thermal effects. The carbon isotopic compositions of saturated hydrocarbons, with the increasing oil reservoirs depth and the enhancing thermal effect, gradually became heavy, but the carbon isotopic compositions of asphaltenes obviously lighten. The reversed distribution degree and fractionation degree of carbon isotope for these deep oil group components also increased, and there are totally reversed distribution in some samples that the distribution of δ13C values of the group components is saturated hydrocarbons﹥aromatics﹥nonhydrocarbons﹥asphaltenes. The vertical distribution characteristics of oil group components of deep marine oil reservoirs in Tabei Uplift may indicate the influences of thermal effects on oil stability.
The carbon isotopic compositions of the oils and its group components, which collected from the deep marine oil reservoirs in Tabei Uplift of Tarim Basin, were analyzed by the MAT252 Isotope Mass Spectrometer. The results showed that carbon isotopic compositions of these deep oils are mainly controlled by their parent material, and less affected by the thermal effects. Reversely, the carbon isotopic compositions and its reversed distributions and fractionations of these deep oil group components, on the basis of inheriting the carbon isotopic composition of parent materials, are evidently affected by the thermal effects. The carbon isotopic compositions of saturated hydrocarbons, with the increasing oil reservoirs depth and the enhancing thermal effect, gradually became heavy, but the carbon isotopic compositions of asphaltenes obviously lighten. The reversed distribution degree and fractionation degree of carbon isotope for these deep oil group components also increased, and there are totally reversed distribution in some samples that the distribution of δ13C values of the group components is saturated hydrocarbons﹥aromatics﹥nonhydrocarbons﹥asphaltenes. The vertical distribution characteristics of oil group components of deep marine oil reservoirs in Tabei Uplift may indicate the influences of thermal effects on oil stability.
2008, 26(4): 552-558.
Abstract:
Within the period of Cenozoic, the downwarping and the sedimentation have good relationships with the uplift of surrounding mountains. The regular change of the position, the range and the plane shape of sedimentary center indicates that Qaidam basin underwent three compressoshear stress field from the north Qilian mountain,the Altyn mountain and Kunlun mountain. The stress field from Altyn Mountain compressed continuously from the beginning to the end of Cenozoic. The stress field from northern and southern boundary also compressed continuously, and experienced a direction change history, the NESW direction(E),the NNESSW direction(E23N11) , nearly SN direction and NESW direction. So, the Cenozoic evolution pattern has been made according to which, the Qaidam Basin experienced four compressoshear stages, their directions are NESW(E),NNESSW(E23N11), nearly SN(N21N22) and NESW(N32Q).
Within the period of Cenozoic, the downwarping and the sedimentation have good relationships with the uplift of surrounding mountains. The regular change of the position, the range and the plane shape of sedimentary center indicates that Qaidam basin underwent three compressoshear stress field from the north Qilian mountain,the Altyn mountain and Kunlun mountain. The stress field from Altyn Mountain compressed continuously from the beginning to the end of Cenozoic. The stress field from northern and southern boundary also compressed continuously, and experienced a direction change history, the NESW direction(E),the NNESSW direction(E23N11) , nearly SN direction and NESW direction. So, the Cenozoic evolution pattern has been made according to which, the Qaidam Basin experienced four compressoshear stages, their directions are NESW(E),NNESSW(E23N11), nearly SN(N21N22) and NESW(N32Q).
2008, 26(4): 575-582.
Abstract:
Bohai basin is characterized by tectonicallyuniform block with steady and slow subsidence, which resulted in lowrelief, low gradient, and highstand lakelevel depositional settings during the Neogene. Excellent reservoirseal combinations and superb conditions for the formation of hydrocarbon traps in the region. Cyclic depositions of shallow water deltaic system which were dominated by fluvial systems showed obvious lobe shape on contour maps and very good lateral connectivity between lobes. Broadly developed, vertically stacked cyclic thick shale layers resulted in multiple sets of reservoirseal combinations. Shallow water deltaic facies are positioned near the prolific hydrocarbonenriched depressions which have been in the peak hydrocarbon generation since Neogene. And the coincidence of neotectonism since Neogene and the peak hydrocarbon generations in the depression has created the excellent basis for the formation of mediumtolarge scale fields in the high quality shallowwater deltaic facies offshore. Therefore, the shallow water deltaic reservoirs still should be the focus targets for exploration for adding new reserves and increasing productions in this region.
Bohai basin is characterized by tectonicallyuniform block with steady and slow subsidence, which resulted in lowrelief, low gradient, and highstand lakelevel depositional settings during the Neogene. Excellent reservoirseal combinations and superb conditions for the formation of hydrocarbon traps in the region. Cyclic depositions of shallow water deltaic system which were dominated by fluvial systems showed obvious lobe shape on contour maps and very good lateral connectivity between lobes. Broadly developed, vertically stacked cyclic thick shale layers resulted in multiple sets of reservoirseal combinations. Shallow water deltaic facies are positioned near the prolific hydrocarbonenriched depressions which have been in the peak hydrocarbon generation since Neogene. And the coincidence of neotectonism since Neogene and the peak hydrocarbon generations in the depression has created the excellent basis for the formation of mediumtolarge scale fields in the high quality shallowwater deltaic facies offshore. Therefore, the shallow water deltaic reservoirs still should be the focus targets for exploration for adding new reserves and increasing productions in this region.
2008, 26(4): 593-601.
Abstract:
Based on cores’ description, electric log, mud logging, cores’ analysis data, seismic survey, etc., the sedimentary facies’ types and their characteristics of early Cretaceous Tenggeer Formation, Baiyinchagan (BYCG) Depression, were studied, as well as their distribution rule. The research showed that fan delta, braided channel delta, lacustrine facies, and turbidities were present in the formation, of which fan delta was located along the steep north border and braided channel delta in the gently south slope. In addition, from the margin to the depocenter of the depression, the sedimentary environments gradually changed from fan delta or braided channel delta to middle depth lacus and deep lacus, and on the flank of fan delta or braided channel delta were deposited shore sediments and meare sediments. The turbidities were distributed in the delta front zone as well as in the prodelta and middle depth lacustrine zone. Generally speaking, the sedimentary facies were different from the east to the west of the depression and differentiated between the south and the north, which were controlled by the neighboring faults and the basin palaeotopography. The fronts of fan delta and braided channel delta are still the important hydrocarbon accumulation area, and the faultsrelated turbidities in them are the potential targets of exploring the lithological hydrocarbon reservoirs.
Based on cores’ description, electric log, mud logging, cores’ analysis data, seismic survey, etc., the sedimentary facies’ types and their characteristics of early Cretaceous Tenggeer Formation, Baiyinchagan (BYCG) Depression, were studied, as well as their distribution rule. The research showed that fan delta, braided channel delta, lacustrine facies, and turbidities were present in the formation, of which fan delta was located along the steep north border and braided channel delta in the gently south slope. In addition, from the margin to the depocenter of the depression, the sedimentary environments gradually changed from fan delta or braided channel delta to middle depth lacus and deep lacus, and on the flank of fan delta or braided channel delta were deposited shore sediments and meare sediments. The turbidities were distributed in the delta front zone as well as in the prodelta and middle depth lacustrine zone. Generally speaking, the sedimentary facies were different from the east to the west of the depression and differentiated between the south and the north, which were controlled by the neighboring faults and the basin palaeotopography. The fronts of fan delta and braided channel delta are still the important hydrocarbon accumulation area, and the faultsrelated turbidities in them are the potential targets of exploring the lithological hydrocarbon reservoirs.
2008, 26(4): 617-623.
Abstract:
In last article, the concept of petroleum collective system and its scales are discussed. The type and scales of petroleum collective system are related with the structure of the sequence, different scale are determined by the sequence of different scales. Petroleum collective system of different scale are determined by the sequence of different scales. The ways and the results of exploration in different scaled petroleum collective system of different scale are also different. So, according to the scales of the sequence and systems, the scales and types of oil and gas field or oil and gas reservoir can be predicted and explorated.
In last article, the concept of petroleum collective system and its scales are discussed. The type and scales of petroleum collective system are related with the structure of the sequence, different scale are determined by the sequence of different scales. Petroleum collective system of different scale are determined by the sequence of different scales. The ways and the results of exploration in different scaled petroleum collective system of different scale are also different. So, according to the scales of the sequence and systems, the scales and types of oil and gas field or oil and gas reservoir can be predicted and explorated.
2008, 26(4): 632-639.
Abstract:
Because the interbeds in monosandbody usually are very narrow, thin, unstable, and hard to predict its attitude, scale, distribution, the researches on the underground thin interbed in monosandbody and its architecture are a few and very difficulty. This paper, taking the depositional model and architecture model of meandering channel as a guideline, fully using the core, log, closely well spacing and so on, puts forward the researching methods of thin interbed architecture of meandering channel sandbody in overburden basin, especially the three types and thirteen methods of extract architecture parameters (dip angle, dip, scale) about thin interbeds of lateral accretion mudstone, the researching methods of interbed density and lateral accretion orbit, basing on the distinguishing, restoring, measuring and calculating of lateral accretion mudstone, lateral accretion surface and abandoned channel, the calculation of the channel geometry and river engineering parameter and the theoretical model of channelsandbody architecture. To overcome this difficult problem provides feasible idea and method. Using these technique, establishes the theoretic and practical model of thin interbed architecture of meandering channel sandbody in PⅠ31b unit of Xingnan oilfield in Songliao Basin.
Because the interbeds in monosandbody usually are very narrow, thin, unstable, and hard to predict its attitude, scale, distribution, the researches on the underground thin interbed in monosandbody and its architecture are a few and very difficulty. This paper, taking the depositional model and architecture model of meandering channel as a guideline, fully using the core, log, closely well spacing and so on, puts forward the researching methods of thin interbed architecture of meandering channel sandbody in overburden basin, especially the three types and thirteen methods of extract architecture parameters (dip angle, dip, scale) about thin interbeds of lateral accretion mudstone, the researching methods of interbed density and lateral accretion orbit, basing on the distinguishing, restoring, measuring and calculating of lateral accretion mudstone, lateral accretion surface and abandoned channel, the calculation of the channel geometry and river engineering parameter and the theoretical model of channelsandbody architecture. To overcome this difficult problem provides feasible idea and method. Using these technique, establishes the theoretic and practical model of thin interbed architecture of meandering channel sandbody in PⅠ31b unit of Xingnan oilfield in Songliao Basin.
2008, 26(4): 610-616.
Abstract:
For determining the distribution pattern of the depositional system of Yanchang Formation in the south of Ordos basin , the authors did a systematic research on the provenance and the characteristics of the mother rock by many methods such as the analysis of rocks and minerals , heavy mineral analysis, rock fragment character, geochemical and seismic profile anlysis etc. . The results indicate that there is mainly controlled by three great sediment source regions in the south of Ordos basin, and more detailed divide five subsources, which are from northeast, north, west, southwest and south. Provenance have favorable spatial combination with depositional system and determine the depositional system pattern of Chang6 oilbearing. Provenance is useful to reasonable deployment of oil gas exploration.
For determining the distribution pattern of the depositional system of Yanchang Formation in the south of Ordos basin , the authors did a systematic research on the provenance and the characteristics of the mother rock by many methods such as the analysis of rocks and minerals , heavy mineral analysis, rock fragment character, geochemical and seismic profile anlysis etc. . The results indicate that there is mainly controlled by three great sediment source regions in the south of Ordos basin, and more detailed divide five subsources, which are from northeast, north, west, southwest and south. Provenance have favorable spatial combination with depositional system and determine the depositional system pattern of Chang6 oilbearing. Provenance is useful to reasonable deployment of oil gas exploration.
2008, 26(4): 655-661.
Abstract:
Three sediment cores, 40～60 cm in depth, extracted at three locations in Pui O Salt marsh of Hong Kong were analyzed for 137Cs content at 1～2 cm intervals. Concentrations of〖KG1〗137Cs were measured γspectrometrically. The results of the 137Cs analyses shown that there were recognizable 137Cs peak and horizon in the 137Cs profiles in the sediment of the three stations. However, there was only one peak in the 137Cs distribution in the two stations, while two peaks were observed in the other station. The maximums of 137Cs activity in the three stations are 2.94 Bq/kg, 4.65 Bq/kg and 6.15 Bq/kg respectively. These values may be compared with that of sediments cores sampled from eastern zone of Hong Kong.Sediment accumulation rates are traditionally calculated by relating the first occurrence of 137Cs in the sediment sequence to the year 1954 and its maximum activity to 1963. But this method does not make full use of the information stored in the 137Cs distribution in the sediment column and sometimes it is difficult to get the right sedimentation rate in coastal area.To obtain more sedimentation process information, a model was fitted to the 137Cs vertical distribution. The difference between the measured and calculated profiles of 137Cs is distinct, accounting for the simplistic model, but the rationality of the model still exists and the difference can be explained. The sediment rates of the three sites were 0.24 cm/a, 0.21 cm/a, 0.34 cm/a according to the model, and some erosion may take place in the surface layer in recent year in P2 and P3 stations. The eroded sediments were about 4.8 and 7cm respectively. And in P1 station the sedimentation rate calculated using the model is coincidence with the result using its maximum activity to 1963. This study indicate that in the coastal area when the sedimentation environment is stead a reliable result can be got using 137Cs dating, and when the sedimentation environment was changed from sedimentation to erosion there is some limitations using 137Cs maximum activity to get the sedimentation rate.
Three sediment cores, 40～60 cm in depth, extracted at three locations in Pui O Salt marsh of Hong Kong were analyzed for 137Cs content at 1～2 cm intervals. Concentrations of〖KG1〗137Cs were measured γspectrometrically. The results of the 137Cs analyses shown that there were recognizable 137Cs peak and horizon in the 137Cs profiles in the sediment of the three stations. However, there was only one peak in the 137Cs distribution in the two stations, while two peaks were observed in the other station. The maximums of 137Cs activity in the three stations are 2.94 Bq/kg, 4.65 Bq/kg and 6.15 Bq/kg respectively. These values may be compared with that of sediments cores sampled from eastern zone of Hong Kong.Sediment accumulation rates are traditionally calculated by relating the first occurrence of 137Cs in the sediment sequence to the year 1954 and its maximum activity to 1963. But this method does not make full use of the information stored in the 137Cs distribution in the sediment column and sometimes it is difficult to get the right sedimentation rate in coastal area.To obtain more sedimentation process information, a model was fitted to the 137Cs vertical distribution. The difference between the measured and calculated profiles of 137Cs is distinct, accounting for the simplistic model, but the rationality of the model still exists and the difference can be explained. The sediment rates of the three sites were 0.24 cm/a, 0.21 cm/a, 0.34 cm/a according to the model, and some erosion may take place in the surface layer in recent year in P2 and P3 stations. The eroded sediments were about 4.8 and 7cm respectively. And in P1 station the sedimentation rate calculated using the model is coincidence with the result using its maximum activity to 1963. This study indicate that in the coastal area when the sedimentation environment is stead a reliable result can be got using 137Cs dating, and when the sedimentation environment was changed from sedimentation to erosion there is some limitations using 137Cs maximum activity to get the sedimentation rate.
2008, 26(4): 676-682.
Abstract:
On the basis of phytolith assemblages from peat surface deposits and some climate indexes, a transfer function of phytolithclimate in Northeast China is established by means of factorial analysis and stepwise regression. Using the function, paleoclimate parameters of Yunshu peat profile were calculated and the paleoclimate evolution is then divided into 7 stages: warmcoldwarmclodwarmcoldwarm. The reconstructed curves also show that the changes of paleoannual wind speed might indicate the following changes of paleotemperature and paleo precipitation, and the warm and wet climate always corresponds with a stable climate system.
On the basis of phytolith assemblages from peat surface deposits and some climate indexes, a transfer function of phytolithclimate in Northeast China is established by means of factorial analysis and stepwise regression. Using the function, paleoclimate parameters of Yunshu peat profile were calculated and the paleoclimate evolution is then divided into 7 stages: warmcoldwarmclodwarmcoldwarm. The reconstructed curves also show that the changes of paleoannual wind speed might indicate the following changes of paleotemperature and paleo precipitation, and the warm and wet climate always corresponds with a stable climate system.
2008, 26(4): 688-696.
Abstract:
Two types of Jurassic mudstones with different total organic contents (TOC) from the northern Qaidam Basin were analyzed for biomarker features in this study. It is showed that these two types of mudstones have pronounced different biomarker compositions. The mudstones with high TOC contents show similar features to other Jurassic source rocks and their derived oils in the western China’s Jurassic petroliferous basins. In contrast, as to the mudstones with low TOC contents, it is characterized by an nalkane envelope that peaks at a low carbon number (e.g., nC16, nC17), Pr/Ph around 1.0, abundance of tricyclic terpane and gammacerane, and detection of 25norhopane series in two samples. Combined with organic petrographic features of mudstones, it is implied that the biomarkers reflect depositional environments and bioprecursors of the mudstones. Bioprecursors of high TOC mudstones consist mainly of algae, cutinites and sporophytes, under relatively anaerobic situations. As to the low TOC mudstones, organic maceral composition is composed mainly of mineral bituminous matrix, which comes from biodegradation of microalga by microbe under relatively more anaerobic conditions. Furthermore, based on a comparison between biomarkers of mudstones analyzed in this study and of presently explored oils, the oil source in the study area was discussed.
Two types of Jurassic mudstones with different total organic contents (TOC) from the northern Qaidam Basin were analyzed for biomarker features in this study. It is showed that these two types of mudstones have pronounced different biomarker compositions. The mudstones with high TOC contents show similar features to other Jurassic source rocks and their derived oils in the western China’s Jurassic petroliferous basins. In contrast, as to the mudstones with low TOC contents, it is characterized by an nalkane envelope that peaks at a low carbon number (e.g., nC16, nC17), Pr/Ph around 1.0, abundance of tricyclic terpane and gammacerane, and detection of 25norhopane series in two samples. Combined with organic petrographic features of mudstones, it is implied that the biomarkers reflect depositional environments and bioprecursors of the mudstones. Bioprecursors of high TOC mudstones consist mainly of algae, cutinites and sporophytes, under relatively anaerobic situations. As to the low TOC mudstones, organic maceral composition is composed mainly of mineral bituminous matrix, which comes from biodegradation of microalga by microbe under relatively more anaerobic conditions. Furthermore, based on a comparison between biomarkers of mudstones analyzed in this study and of presently explored oils, the oil source in the study area was discussed.
2008, 26(4): 705-708.
Abstract:
The empirical relationship between methyldiamantane parameter and the corresponding vitrinite reflectance value has been established based on their experimental data of the source rocks in Jiyang Depression. This empirical relationship has been used to evaluate the maturity of the condensate in Jiyang Depression. The maturity of the condensate in this area is believed to be highly mature(Ro＞1.3%). Meanwhile, by means of the dimenthyldiamantane parameter, the condensate in Jiyang depression can be divided into two types, which were from the humic kerogen in coal deposit and the mixedtype kerogen in lacustrine facies, respectively.
The empirical relationship between methyldiamantane parameter and the corresponding vitrinite reflectance value has been established based on their experimental data of the source rocks in Jiyang Depression. This empirical relationship has been used to evaluate the maturity of the condensate in Jiyang Depression. The maturity of the condensate in this area is believed to be highly mature(Ro＞1.3%). Meanwhile, by means of the dimenthyldiamantane parameter, the condensate in Jiyang depression can be divided into two types, which were from the humic kerogen in coal deposit and the mixedtype kerogen in lacustrine facies, respectively.
