1994 Vol. 12, No. 1
column
Display Method:
1994, 12(1): 1-7.
Abstract:
The intraplate basin of Devonian in South China formed by collsion between Yangtze Plate and Huaxia Plate during Caledonian tectonic cycle. From bottom to top, the strata of Devonian rnuld be divided into four depositional sequences: The first sequence rnnsists of sediments from the Lochkovian to Middle Emsian period. The sedimentary strata of terrertsial facies from Lochkovian to Pragian period rnuld be the lwstand systems tract (LST) formed during sea level fall in post一orogeny.“its bax surface belonged to type I sequence boundary unrnnformity. The distribution of sedimentary body, the conglomerate and sandy shall of Lian一Huashan Fororation and the lower part of Na Gaoling Formation belonged to overlap sediments and lowstand fan which were formed by stream reworking of eluvial material located at erosion surface; in western Guangxi: The LST consists of violet一red sandy rnnglomerate and sandstone in center of Guangxi but lack of in orthern Guangxi and southern Hunan. The transgressive systems tract (TST) consists of terrigenous clastic rock of littoral and tidal flat facies. The condensed section (CS) was made up of brachiopod biostrome in middle part of Maiqu Formation. The highstand systems tract (HST) composed of sandstone and mudstone. The second depositional sequence consists of sediments from the late Emsian to Early一Middle Givertian period. The base boundary line of this sequence shows type I sequence boundary unconformity and erosion surface and rejuvenation of stream. The top sequence boundary shows palaeokarst. The LST has been found in Guangxi. The TST consists of terrigenous clastic rock of littoral facies, biomicrite, bioclastic limestone and shale and carbonate rock of reef and bank facies. The CS composed of biostrome. The HST consists of reefal limestone,bioclastic hmPaLOne. micrite and dolostone.
The intraplate basin of Devonian in South China formed by collsion between Yangtze Plate and Huaxia Plate during Caledonian tectonic cycle. From bottom to top, the strata of Devonian rnuld be divided into four depositional sequences: The first sequence rnnsists of sediments from the Lochkovian to Middle Emsian period. The sedimentary strata of terrertsial facies from Lochkovian to Pragian period rnuld be the lwstand systems tract (LST) formed during sea level fall in post一orogeny.“its bax surface belonged to type I sequence boundary unrnnformity. The distribution of sedimentary body, the conglomerate and sandy shall of Lian一Huashan Fororation and the lower part of Na Gaoling Formation belonged to overlap sediments and lowstand fan which were formed by stream reworking of eluvial material located at erosion surface; in western Guangxi: The LST consists of violet一red sandy rnnglomerate and sandstone in center of Guangxi but lack of in orthern Guangxi and southern Hunan. The transgressive systems tract (TST) consists of terrigenous clastic rock of littoral and tidal flat facies. The condensed section (CS) was made up of brachiopod biostrome in middle part of Maiqu Formation. The highstand systems tract (HST) composed of sandstone and mudstone. The second depositional sequence consists of sediments from the late Emsian to Early一Middle Givertian period. The base boundary line of this sequence shows type I sequence boundary unconformity and erosion surface and rejuvenation of stream. The top sequence boundary shows palaeokarst. The LST has been found in Guangxi. The TST consists of terrigenous clastic rock of littoral facies, biomicrite, bioclastic limestone and shale and carbonate rock of reef and bank facies. The CS composed of biostrome. The HST consists of reefal limestone,bioclastic hmPaLOne. micrite and dolostone.
1994, 12(1): 16-22.
Abstract:
The reef front, reef core, reef flat and reef back could be distinguished in the Late Devonian organic reef in Sanlixia, which is 180 meters thick and has a width of 4000 meters. The N一S trend chain of reefs, including the reef in Sanlixia and other other south reefs,comprises the N一S barrier reef complex in Zhenan一Xunyang region. The fossils in the reef include stromatoporoids, corals, chaetets, alga, brachiopods, crinoids,gas- teropods, bryozooids, ostracods, lamellibranchiates tentaculitids etc.,totally amounting eleven kinds. The former four kinds are major reef一building organisms, and make up about 90 0 o of tolal organisms in the reef. Brachiopods and crinoids are major adherent organism. The organic reef developed in the margin of a horst type platform during the development of a continental margin rift一faulted depression basin, and the development of the reef could be divided into four stages; bank一reef stage, growth, prosperous stage and declining stage. Organisms during bank一reef stage were mainly brachiopods, crinoids。“alga, which formed organic bank. Organisms during the growth stage were mainly branched coral, tabular stromatoporoids and alga,which formed bafflestone and bindstone. All kinds of organisms could be found in different facies in the prosperous stage, for example, lamp stromatoporoids, corals,and chaetets formed framestone in the reef core, branch stromatoporoids and corals formed the baffle- stone in reef core and reef flat, tabular and crustified stromatoporoids and alga formed bindstone in reef flat. And the adherent organisms distrbuted in all facies. Branch coral were the major reef一building organism in the declining stage, which formed the bafflestone. The reef came to an end by the increasing of the water depth and mud. The synsedimentary rift一faulting resulted in the uplift of submarine topography, thus contributing to the growth of the reef-building organisms, and the relief of submarine topography and variation of sedimentary facies was enhanced by the rapid development of organic reef , which resulted in the lagoon graben basin suitable for containing and deposition of hot ore一bearing brine.
The reef front, reef core, reef flat and reef back could be distinguished in the Late Devonian organic reef in Sanlixia, which is 180 meters thick and has a width of 4000 meters. The N一S trend chain of reefs, including the reef in Sanlixia and other other south reefs,comprises the N一S barrier reef complex in Zhenan一Xunyang region. The fossils in the reef include stromatoporoids, corals, chaetets, alga, brachiopods, crinoids,gas- teropods, bryozooids, ostracods, lamellibranchiates tentaculitids etc.,totally amounting eleven kinds. The former four kinds are major reef一building organisms, and make up about 90 0 o of tolal organisms in the reef. Brachiopods and crinoids are major adherent organism. The organic reef developed in the margin of a horst type platform during the development of a continental margin rift一faulted depression basin, and the development of the reef could be divided into four stages; bank一reef stage, growth, prosperous stage and declining stage. Organisms during bank一reef stage were mainly brachiopods, crinoids。“alga, which formed organic bank. Organisms during the growth stage were mainly branched coral, tabular stromatoporoids and alga,which formed bafflestone and bindstone. All kinds of organisms could be found in different facies in the prosperous stage, for example, lamp stromatoporoids, corals,and chaetets formed framestone in the reef core, branch stromatoporoids and corals formed the baffle- stone in reef core and reef flat, tabular and crustified stromatoporoids and alga formed bindstone in reef flat. And the adherent organisms distrbuted in all facies. Branch coral were the major reef一building organism in the declining stage, which formed the bafflestone. The reef came to an end by the increasing of the water depth and mud. The synsedimentary rift一faulting resulted in the uplift of submarine topography, thus contributing to the growth of the reef-building organisms, and the relief of submarine topography and variation of sedimentary facies was enhanced by the rapid development of organic reef , which resulted in the lagoon graben basin suitable for containing and deposition of hot ore一bearing brine.
1994, 12(1): 40-46.
Abstract:
The research about the following three aspects provides the evidences for that, the depositional environwent when Heshan Formation sediments deposited was mainly shallow, and the carbonate platform surface was relief. 1. Almost all the limestones composing Heshan coal-bearing formation are shallow-water limestones. 2. Small quantity sponge-reef rocks of Heshan coal-bearing formation are provided with the characteristics of dispersed and isolated small reefs. 3. There was a depositional break between No. N coal-seam and it's indirect carbonate floor. The discovery of the paleosol, which originated from intertidal blue alage rock underwent soil weathering and siliconizing on supratidal zone, under neath the main coal-seam, and discovery of terrestria seat earth, and the contents of some microelements in the No. N coal-seam are nearing that of plants of fresh water, demonstrates that the coal-seam in Heshan coalfield formed in the marshes arised on the abundonment carbonate tidal flat and some of them in minor region, were originated under the condition of the process of turning the closed water一body into swamps on the surface of the carbonate platform.
The research about the following three aspects provides the evidences for that, the depositional environwent when Heshan Formation sediments deposited was mainly shallow, and the carbonate platform surface was relief. 1. Almost all the limestones composing Heshan coal-bearing formation are shallow-water limestones. 2. Small quantity sponge-reef rocks of Heshan coal-bearing formation are provided with the characteristics of dispersed and isolated small reefs. 3. There was a depositional break between No. N coal-seam and it's indirect carbonate floor. The discovery of the paleosol, which originated from intertidal blue alage rock underwent soil weathering and siliconizing on supratidal zone, under neath the main coal-seam, and discovery of terrestria seat earth, and the contents of some microelements in the No. N coal-seam are nearing that of plants of fresh water, demonstrates that the coal-seam in Heshan coalfield formed in the marshes arised on the abundonment carbonate tidal flat and some of them in minor region, were originated under the condition of the process of turning the closed water一body into swamps on the surface of the carbonate platform.
1994, 12(1): 56-65.
Abstract:
The Ordos basin, situated in the western part of the North China platform, has been classified as an intracrationic basin. The basin is rich in oil and gas resoureces contained three kinds of source rocks. In the exploration for oil and gas an important breakthrouths have been made in recent years. A giant gas field has been discovered in Jingbian county in the central part of the basin. Based on analyses of data of vitrinite reflectance, fluid in clusions and apatite fisson track, this paper has determined the high palaeothermal filed of the Ordos basin in the late mesozoic. The palaeotemperature in the palaeozoic strata is abort 150~240℃., the highest temperature exceeding 270℃,which is higher than the present tempreture. The palaeotemperature gradient (3. 5~-4. 0℃/100m) which is closely related to tectonic activity also exceeds that (2. 89℃/1OOm) of the present. Apatite fission track data show that there is a cooling event which ocurred in 20 to 23 Ma. The uplift scope in North shaanxi slope in the east is obviously bigger than in the Tianhuan syncline. Reseach on relations between the thermal history of the Ordos basin and oil gas fields suggests that low temperature gradients in paleozic and early mesozoic times was favourable for preservation of organic material and the gas generation stage was postponed. The late Mesozoic which is characterized by highertemperatures in the period of main gas generation and migration of paleozoic coal series and carbonates. The late gas generation stage and lack of faults were favourable for preservation of giant gas fields. The central palaeouplift in the basin which has good carbonate reservoirs and is close to gas generation regions should be first chosen as an exploration target. The southern part of the yiming uplift, the northern Part of the weibei uplift, the eastern part of the north shaanxi slope and the western part of Tianhuan syncline are also potential regions of gas migration and the reserve bases for looking for new gas fields.
The Ordos basin, situated in the western part of the North China platform, has been classified as an intracrationic basin. The basin is rich in oil and gas resoureces contained three kinds of source rocks. In the exploration for oil and gas an important breakthrouths have been made in recent years. A giant gas field has been discovered in Jingbian county in the central part of the basin. Based on analyses of data of vitrinite reflectance, fluid in clusions and apatite fisson track, this paper has determined the high palaeothermal filed of the Ordos basin in the late mesozoic. The palaeotemperature in the palaeozoic strata is abort 150~240℃., the highest temperature exceeding 270℃,which is higher than the present tempreture. The palaeotemperature gradient (3. 5~-4. 0℃/100m) which is closely related to tectonic activity also exceeds that (2. 89℃/1OOm) of the present. Apatite fission track data show that there is a cooling event which ocurred in 20 to 23 Ma. The uplift scope in North shaanxi slope in the east is obviously bigger than in the Tianhuan syncline. Reseach on relations between the thermal history of the Ordos basin and oil gas fields suggests that low temperature gradients in paleozic and early mesozoic times was favourable for preservation of organic material and the gas generation stage was postponed. The late Mesozoic which is characterized by highertemperatures in the period of main gas generation and migration of paleozoic coal series and carbonates. The late gas generation stage and lack of faults were favourable for preservation of giant gas fields. The central palaeouplift in the basin which has good carbonate reservoirs and is close to gas generation regions should be first chosen as an exploration target. The southern part of the yiming uplift, the northern Part of the weibei uplift, the eastern part of the north shaanxi slope and the western part of Tianhuan syncline are also potential regions of gas migration and the reserve bases for looking for new gas fields.
1994, 12(1): 72-80.
Abstract:
The salt-dissolution refers to halite nuneral dissolution in the carbonate reservoir rock of the Ordos basin, which is the main factor to form secondary pores (here called as salt-dissolved pore). Reservoir rocks containning salt-dissolved pore are widely distributed on top of Majiagou Formation of Ordovician in the tentral Ordos basin, and ocarpied an area of more than 30,000 km2. On the bases of a large number of data obtained from core observation, thin section determination,cathodo luminescence, SEM, electron probe and so on, it can be seen that the gas-bearing bed of Majiagou Formation closely velated to salt-dissolution. The gas output and rock's physical properties dependon the openning extent of the salt-dissolved pore. The salt-dissolution caused an increase of porosity in carbonate reservoir, and at the same time, the fluid deposition in the previous porosity through leading-phreatic water.In water stagnant region the fight lithologic borrier can be formed. Halite}cry-stallization took place in sedimentary period, which was easily-dissolved substance in carbonate rock. And abundant salt-dissolved pores were produced in epidiagenesis. The vegional difference of pore filling lead to the difference and anisotropise of pore space in carbonate reservoir rock. It was the "loss" and "compensation" of rock itself that formed the vegional diagenetic trap or lithologic barrier.
The salt-dissolution refers to halite nuneral dissolution in the carbonate reservoir rock of the Ordos basin, which is the main factor to form secondary pores (here called as salt-dissolved pore). Reservoir rocks containning salt-dissolved pore are widely distributed on top of Majiagou Formation of Ordovician in the tentral Ordos basin, and ocarpied an area of more than 30,000 km2. On the bases of a large number of data obtained from core observation, thin section determination,cathodo luminescence, SEM, electron probe and so on, it can be seen that the gas-bearing bed of Majiagou Formation closely velated to salt-dissolution. The gas output and rock's physical properties dependon the openning extent of the salt-dissolved pore. The salt-dissolution caused an increase of porosity in carbonate reservoir, and at the same time, the fluid deposition in the previous porosity through leading-phreatic water.In water stagnant region the fight lithologic borrier can be formed. Halite}cry-stallization took place in sedimentary period, which was easily-dissolved substance in carbonate rock. And abundant salt-dissolved pores were produced in epidiagenesis. The vegional difference of pore filling lead to the difference and anisotropise of pore space in carbonate reservoir rock. It was the "loss" and "compensation" of rock itself that formed the vegional diagenetic trap or lithologic barrier.
1994, 12(1): 98-105.
Abstract:
The Changli coastal dunefield,situated on the southwestern shore of Liaodong Bay. is one of the largest coastal dunefields in China. The dunefield forms a strip 2一3 km wide and more than 30 km long. The dominant dune type in the studied area is transverse dunes,and these dunes have sqpaings of 80一600m with a height 5-38m. Most dune crests are oriented normal to the prevailing wind vector (NE一NEE)·There are close relationships between dune height,width and sapcing (r>0. 8). Eolian sand ripples,composed of well一sorted medium to fine一grained sand,occur mainly on the stoss sides of dunes,with their long axes parallel to the slope. Granule ripples form in the interdune lows of coarse lag deposits. They are form in the interdune lows of coarse lag deposits. They are usually asymmetrical and large,and move slowly than the sand ripples. In the m ain trenches,oriented at right angles to the dune crests,two types of stratifications were recongnized. Low一angle cross一strata sets occur on the surfacial parts of the stoss sides,they dip upwind (NE50一70),with angles less than 110. High一angle cross一strata sets are the dominant type of stratification in studied area,mostly they are tabular一planar,and measurements show the foreset strata with southwestern dips of 28°一31°. Sets of cross一strata in the beach are relatively thin and slightly dipping with angles less than 60. Sand dunes may occur where there is a协rge supply of sand,a wind to move it,and a place in which it can accumulate. Changli Coast,with wide and low一angle beach,is ideal location for these criteria to be met. The original sand source for the Changli coastal dunes is Luanhe River. The abundant fluvial sediments are transported north ward and deposited on the beach by the alongshore currents and waves. The onshore wind blows the well一sorted sand grains off the beach and transports them landward,then builds up large transverse dunes. At present time,the coastal dunes are still active.
The Changli coastal dunefield,situated on the southwestern shore of Liaodong Bay. is one of the largest coastal dunefields in China. The dunefield forms a strip 2一3 km wide and more than 30 km long. The dominant dune type in the studied area is transverse dunes,and these dunes have sqpaings of 80一600m with a height 5-38m. Most dune crests are oriented normal to the prevailing wind vector (NE一NEE)·There are close relationships between dune height,width and sapcing (r>0. 8). Eolian sand ripples,composed of well一sorted medium to fine一grained sand,occur mainly on the stoss sides of dunes,with their long axes parallel to the slope. Granule ripples form in the interdune lows of coarse lag deposits. They are form in the interdune lows of coarse lag deposits. They are usually asymmetrical and large,and move slowly than the sand ripples. In the m ain trenches,oriented at right angles to the dune crests,two types of stratifications were recongnized. Low一angle cross一strata sets occur on the surfacial parts of the stoss sides,they dip upwind (NE50一70),with angles less than 110. High一angle cross一strata sets are the dominant type of stratification in studied area,mostly they are tabular一planar,and measurements show the foreset strata with southwestern dips of 28°一31°. Sets of cross一strata in the beach are relatively thin and slightly dipping with angles less than 60. Sand dunes may occur where there is a协rge supply of sand,a wind to move it,and a place in which it can accumulate. Changli Coast,with wide and low一angle beach,is ideal location for these criteria to be met. The original sand source for the Changli coastal dunes is Luanhe River. The abundant fluvial sediments are transported north ward and deposited on the beach by the alongshore currents and waves. The onshore wind blows the well一sorted sand grains off the beach and transports them landward,then builds up large transverse dunes. At present time,the coastal dunes are still active.
1994, 12(1): 112-116.
Abstract:
Presented in this paper are the changing characteristics and its paleoclimatic and environmental.aignificanoe of magnessium and aluminium content ration (m value) of loessic sections of Quaternary in arid and relatively arid regions of China. The changes of the m values in loess一paleosol show the changes of the paleoclimatic aridity and wet.during loess deposition and paleosol development. During loess deposition. the m valurea are higher. the variation curves of the m values appear the peaks showing the arid climate and environ- ment. During paleosol development .the m values are lower. the variation curves of the m valures appear valley showing the relative wet climate and environment. The result of study of magneatum and aluminium content rations of loess sections in arid and relatively aric rgeions of China shows alternatives of four times of arid and wet climate since late Pleistocene at least.
Presented in this paper are the changing characteristics and its paleoclimatic and environmental.aignificanoe of magnessium and aluminium content ration (m value) of loessic sections of Quaternary in arid and relatively arid regions of China. The changes of the m values in loess一paleosol show the changes of the paleoclimatic aridity and wet.during loess deposition and paleosol development. During loess deposition. the m valurea are higher. the variation curves of the m values appear the peaks showing the arid climate and environ- ment. During paleosol development .the m values are lower. the variation curves of the m valures appear valley showing the relative wet climate and environment. The result of study of magneatum and aluminium content rations of loess sections in arid and relatively aric rgeions of China shows alternatives of four times of arid and wet climate since late Pleistocene at least.
1994, 12(1): 8-15.
Abstract:
A Seismic一Sequence Stratigraphy Supplementary System of Sedimentary Basins (abbreviated as 4S)was established by the author based on studies of the basins such as Caidam, Jungar, Erdos, North China and Nanning. 4S, which wnsisting of three main blocks, data of exploration statistics, establishment of quantificational method and the opening of the model, is a microsoft system mnsistuated of more than 4000 sorce statements, its functions include the synthetical data一。peration of ground geology, seismology, well logging and sample analysis quantitative study many of the problems realated to seismic一sequence stratigraphy of the target stratum such as the sedimentary facies, sedimentary system,flow direction of palaeodrainage, prospect the distribution of source,reservoir and cap rocks of hydrocarbon generation, seis.mic simulation of the model of two一dimentional sedimentary model, three一dimentional slice of sedimentary sequence and its surficial morphologic image and so on. Both of the data systems used in 4S and the target result are different from the currently adopted ones that used especially for the explaination of seismic data and basin modelling. There are five spectattttes of 4S: (1) lnverstnea aata. 1t mcmaes an of the aata ana stattsttcs of surncial geology, well logging, seismic exploration,, sample analysis, downhole oil一gas determination, and digitized concepts and experiences.(2)Quantitatited analysis. All of the descriptive information are digitized, this led to the quantitative analysis of lithology, sedimentary environment, sedimentary system and so on. (3) Pat- terned explaination. Set up a model on the basis of。known spot firstly, then use it in the frontier area. (4) Software一equipped system, i. e.,block programme structure,it can data out more than 40000 statements, over 40 figures and 20 more tables. (5) Automatized programme. There are 3 blocks, 8 grades of menu and more than 180 sub一routines that can run as a whole programs or seperately,moreover, the oprator can joint the sub一routines as he will. 4S data, figures and knowledge bank are sub一divided into four sub一reservoirs, they are:original data source,intermediate data, figure and knowledge material. Original data includes the message of outcrups, section of drilling hole, seismic exploitation, sample teat, and downwell oil一gas determination Intermediate data is composed of the data generated during the running of system; Figure sub一bank consists of the source figure and final figures,Knowledge sub一bank is the foudation of general concepts and some special concepts, such as sedimentary facies and standard models. There are eight explainning models of 4S that established based on the konwn part of a basin, they are: (1) Time一lithologic sequence Markov chain model. Use the quantificated method of Markov chain to determine the known lithologic sequence,extract out the multi一models of lithofacies,and contrast them with standard models,then confirm the genetic type of the litho一seqquences. Generally, the results will be better if the lithologic assembledge profile is used to analysis the count matrix and transformation matrix of every lithostratigraphic unit. (2) Frenquence spcetrum analysis model of time一lithologic sequence. Marke spectrum analysis on the known sequences and identify the maximum cycle and wave band of a certain typical geological feature that found in a sequence. The maximum cycle and wave band should be similar if the sequences have correlated ge- netic type. That is to say, if a geological phenominon occured in two sequences isochronously and with simi- lar extent,then the sequences should be genetically correlation. (3) Various kind of poly一statistical model:4S can simulate data by means of funtional relations, it e- quipped with basically complete poly一statistical methods, and has the digit一opration such as digit wave filter, Fulier period analysis and correlation analysis. (4) Velocity一lithologic assembledge of sedimentary facies model. This model is the basis to explain of the underground facies. It is revealed that as the sedimentary sequences of terrigenous basins are thin polylithologic assembledges, so the seismic velocity, besides its normal relation with the burial depth and geological time,is mainly affected by the factors that are related to sedimentary condition such as lithologic assembledge of strata sequences and grain size, and a lithologic sequence of a defined sedimentary facies can affect the seismic velocity to a certain degree. Based on this law, we can identify sedimentary facies by use of seismic parameters. (5) Total porosity一layer velocity of a known oil一gas reservoir and cap model. Based on the logging velocity, density and porosity of a known oil一gas source,reservoir and cap layer, associated with the real (practically measured) parameters such as density, porosity and permeablility, two explainning models of ve- locity一mud一sand contents and velocity一total porosity can be directly and statistically erected. This method is more .suitable and practical than the Wyllie equation and Cokriging statistical technique in the study of terrigenous sedimentary basins.
A Seismic一Sequence Stratigraphy Supplementary System of Sedimentary Basins (abbreviated as 4S)was established by the author based on studies of the basins such as Caidam, Jungar, Erdos, North China and Nanning. 4S, which wnsisting of three main blocks, data of exploration statistics, establishment of quantificational method and the opening of the model, is a microsoft system mnsistuated of more than 4000 sorce statements, its functions include the synthetical data一。peration of ground geology, seismology, well logging and sample analysis quantitative study many of the problems realated to seismic一sequence stratigraphy of the target stratum such as the sedimentary facies, sedimentary system,flow direction of palaeodrainage, prospect the distribution of source,reservoir and cap rocks of hydrocarbon generation, seis.mic simulation of the model of two一dimentional sedimentary model, three一dimentional slice of sedimentary sequence and its surficial morphologic image and so on. Both of the data systems used in 4S and the target result are different from the currently adopted ones that used especially for the explaination of seismic data and basin modelling. There are five spectattttes of 4S: (1) lnverstnea aata. 1t mcmaes an of the aata ana stattsttcs of surncial geology, well logging, seismic exploration,, sample analysis, downhole oil一gas determination, and digitized concepts and experiences.(2)Quantitatited analysis. All of the descriptive information are digitized, this led to the quantitative analysis of lithology, sedimentary environment, sedimentary system and so on. (3) Pat- terned explaination. Set up a model on the basis of。known spot firstly, then use it in the frontier area. (4) Software一equipped system, i. e.,block programme structure,it can data out more than 40000 statements, over 40 figures and 20 more tables. (5) Automatized programme. There are 3 blocks, 8 grades of menu and more than 180 sub一routines that can run as a whole programs or seperately,moreover, the oprator can joint the sub一routines as he will. 4S data, figures and knowledge bank are sub一divided into four sub一reservoirs, they are:original data source,intermediate data, figure and knowledge material. Original data includes the message of outcrups, section of drilling hole, seismic exploitation, sample teat, and downwell oil一gas determination Intermediate data is composed of the data generated during the running of system; Figure sub一bank consists of the source figure and final figures,Knowledge sub一bank is the foudation of general concepts and some special concepts, such as sedimentary facies and standard models. There are eight explainning models of 4S that established based on the konwn part of a basin, they are: (1) Time一lithologic sequence Markov chain model. Use the quantificated method of Markov chain to determine the known lithologic sequence,extract out the multi一models of lithofacies,and contrast them with standard models,then confirm the genetic type of the litho一seqquences. Generally, the results will be better if the lithologic assembledge profile is used to analysis the count matrix and transformation matrix of every lithostratigraphic unit. (2) Frenquence spcetrum analysis model of time一lithologic sequence. Marke spectrum analysis on the known sequences and identify the maximum cycle and wave band of a certain typical geological feature that found in a sequence. The maximum cycle and wave band should be similar if the sequences have correlated ge- netic type. That is to say, if a geological phenominon occured in two sequences isochronously and with simi- lar extent,then the sequences should be genetically correlation. (3) Various kind of poly一statistical model:4S can simulate data by means of funtional relations, it e- quipped with basically complete poly一statistical methods, and has the digit一opration such as digit wave filter, Fulier period analysis and correlation analysis. (4) Velocity一lithologic assembledge of sedimentary facies model. This model is the basis to explain of the underground facies. It is revealed that as the sedimentary sequences of terrigenous basins are thin polylithologic assembledges, so the seismic velocity, besides its normal relation with the burial depth and geological time,is mainly affected by the factors that are related to sedimentary condition such as lithologic assembledge of strata sequences and grain size, and a lithologic sequence of a defined sedimentary facies can affect the seismic velocity to a certain degree. Based on this law, we can identify sedimentary facies by use of seismic parameters. (5) Total porosity一layer velocity of a known oil一gas reservoir and cap model. Based on the logging velocity, density and porosity of a known oil一gas source,reservoir and cap layer, associated with the real (practically measured) parameters such as density, porosity and permeablility, two explainning models of ve- locity一mud一sand contents and velocity一total porosity can be directly and statistically erected. This method is more .suitable and practical than the Wyllie equation and Cokriging statistical technique in the study of terrigenous sedimentary basins.
1994, 12(1): 23-31.
Abstract:
Some reefs of Middle Carboniferous were discovered in Taizi River ba}tn. Located in Xiaoyu limestone bed, they emerge intermittently in a row on the surface, extending east一westernly 16 kilometers. They are situated in the Niutnaoling, Chigou and Yaoziyu of Benxi. The reefs are very abundant in organisms. The principal builders are Chaetetes penchiensis and Arachnastraea manchurica. Some algae also stabilized sediments by trapping and binding in the process of buildup. Atcessory organisms are Brachiopods, Bryozoans, Sponges, Crinoids, Foraminifera, Gastropod, Ostracoda,etc. The process of buildup is very simple. At the early stage, the non一typical bioherms were formed by algae on the organic bank. At the middle stage, become principal builders, Chaeuus penchiensis colonies and Arachsiastraea manchurica colonies laerally linked into thick board skeleton, which covered carbonate sediments, forming strong framework of reefs. At the late stage, the principal builders disappeared rapidly, and then Crinoids began to baffle sediments helpeds disappeared rapidly, and then Crinoids began to. baffle sediments helped by algae. In the end, the organisms were not able to buildup bioherms and the process of buildup stopped. The core of reefs may be divided into three microfacies in the area. They are; (1) Bindstone microfacies;(2) Bind一coverstone microfacies;(3) Bind一bafflestone microfacies. These reefs being discovered have extremely similar composition of organisms, type of buildup and character of framework in Taizi River basin. These bioherms occur in an uncontinous belt, in line with the direction of the regional sedimentary facies belt. Therefore it is considered that these bioherms belong to one fringe feef system.
Some reefs of Middle Carboniferous were discovered in Taizi River ba}tn. Located in Xiaoyu limestone bed, they emerge intermittently in a row on the surface, extending east一westernly 16 kilometers. They are situated in the Niutnaoling, Chigou and Yaoziyu of Benxi. The reefs are very abundant in organisms. The principal builders are Chaetetes penchiensis and Arachnastraea manchurica. Some algae also stabilized sediments by trapping and binding in the process of buildup. Atcessory organisms are Brachiopods, Bryozoans, Sponges, Crinoids, Foraminifera, Gastropod, Ostracoda,etc. The process of buildup is very simple. At the early stage, the non一typical bioherms were formed by algae on the organic bank. At the middle stage, become principal builders, Chaeuus penchiensis colonies and Arachsiastraea manchurica colonies laerally linked into thick board skeleton, which covered carbonate sediments, forming strong framework of reefs. At the late stage, the principal builders disappeared rapidly, and then Crinoids began to baffle sediments helpeds disappeared rapidly, and then Crinoids began to. baffle sediments helped by algae. In the end, the organisms were not able to buildup bioherms and the process of buildup stopped. The core of reefs may be divided into three microfacies in the area. They are; (1) Bindstone microfacies;(2) Bind一coverstone microfacies;(3) Bind一bafflestone microfacies. These reefs being discovered have extremely similar composition of organisms, type of buildup and character of framework in Taizi River basin. These bioherms occur in an uncontinous belt, in line with the direction of the regional sedimentary facies belt. Therefore it is considered that these bioherms belong to one fringe feef system.
1994, 12(1): 47-55.
Abstract:
The Blanzy一Monctceau coal basin is an intramontaine rift located in North一East of massif centre of France. This paper cleals with the organo一facies in the first coal seam of basin, which is variable both in thickness and in quality. Macroscopically, the seam is largely dominated by clarain. The vertical variations in lustre, brightness and texture on polished section allow to subdivide the sample into many intervals and thus to be classified as coal facies. Eight facies are thus idendified. Detailled analyses have been performed for these coal facies by organic petrology approach and pyrolysis Rock一Eval. Facies A is telocollinite一rich and mineral一poor, contain much inertinite (fusinite) and low to very low percentages of exinite, whereas facies B is vitrinite一rich (telocollinite and desocollinite) and miner- al一poor, with median percentages of exinite and low to very low percentages of inertinite. Facies C is vitri- rite一rich (phyllovitrinite and desmocollinite) and mineral一poor, with much exinite and low to very low percentage of inertinite. Facies D contain more telocollinite and vitrodetrinite and high percentage of mineral (quartz and clay). Facies E contain more desmocollinite than telocollinite, with median percentage of mineral (pyrite). Facies F contain high percentage of corpocollinite and mineral (clay). Facies G and H is mineralrich, but different in occurrence. Use of the macerals as botanical markers and the texture (particle size, form, psephicity, gradation in- tensity etc.)as environment markers allow one to attribute each coal facies to different depositional environment .on the other hand, consideration of spatial distribution of facies in coal seam allows one to reconstruct the processes of coal formation. This coal seam is majoy allocthnous, with arborecent input. Within the coal seam, it exsists a cyclic deposit constructed by four major facies (facies A, G,B or C),similar to cyclothem present in coal一bearing formation. It is probably due to differential compaction in peat. Variation in coal faties is caused predominantly by water dynamic condition and water level and finally influences the physi一 chemical properties of maceral, such as vitrinite}reflectance, exinite fluorescence and hydrogen index of fatree.
The Blanzy一Monctceau coal basin is an intramontaine rift located in North一East of massif centre of France. This paper cleals with the organo一facies in the first coal seam of basin, which is variable both in thickness and in quality. Macroscopically, the seam is largely dominated by clarain. The vertical variations in lustre, brightness and texture on polished section allow to subdivide the sample into many intervals and thus to be classified as coal facies. Eight facies are thus idendified. Detailled analyses have been performed for these coal facies by organic petrology approach and pyrolysis Rock一Eval. Facies A is telocollinite一rich and mineral一poor, contain much inertinite (fusinite) and low to very low percentages of exinite, whereas facies B is vitrinite一rich (telocollinite and desocollinite) and miner- al一poor, with median percentages of exinite and low to very low percentages of inertinite. Facies C is vitri- rite一rich (phyllovitrinite and desmocollinite) and mineral一poor, with much exinite and low to very low percentage of inertinite. Facies D contain more telocollinite and vitrodetrinite and high percentage of mineral (quartz and clay). Facies E contain more desmocollinite than telocollinite, with median percentage of mineral (pyrite). Facies F contain high percentage of corpocollinite and mineral (clay). Facies G and H is mineralrich, but different in occurrence. Use of the macerals as botanical markers and the texture (particle size, form, psephicity, gradation in- tensity etc.)as environment markers allow one to attribute each coal facies to different depositional environment .on the other hand, consideration of spatial distribution of facies in coal seam allows one to reconstruct the processes of coal formation. This coal seam is majoy allocthnous, with arborecent input. Within the coal seam, it exsists a cyclic deposit constructed by four major facies (facies A, G,B or C),similar to cyclothem present in coal一bearing formation. It is probably due to differential compaction in peat. Variation in coal faties is caused predominantly by water dynamic condition and water level and finally influences the physi一 chemical properties of maceral, such as vitrinite}reflectance, exinite fluorescence and hydrogen index of fatree.
1994, 12(1): 66-71.
Abstract:
Cambrian-Odovician carbonate rocks are one of the main reservoirs in the Northern Tarim Basin. Deep dissolution has important role in the formation of effective porosity of the reservoir rocks. The main charac- teristics of deep dissolution in the region are non-fabric selective dissolution, and dissolution developed mainly along stylolites and fractures. The main evidence for deep dissolution are: 1. The dissolution of late stage diagenetic fabrics or the dissolution developed along late stage diagenetic fabrics (such as atylotea and fractures), 2. The dissolution pores filled with hydrocarbon or other late stage diagenetic minerals; 3. Not only the rnvered region, but also the Kepin outcrop region (continuous depression in early stage一from Cambrian to early Permian, uplift in late stage一from late Permian to present) have above charac- teristics. Based on preliminary analysis, this paper considers that the deep dissolution is mainly related to Co2-bearing acid water produced by organic matter thermal evolution of source rock.
Cambrian-Odovician carbonate rocks are one of the main reservoirs in the Northern Tarim Basin. Deep dissolution has important role in the formation of effective porosity of the reservoir rocks. The main charac- teristics of deep dissolution in the region are non-fabric selective dissolution, and dissolution developed mainly along stylolites and fractures. The main evidence for deep dissolution are: 1. The dissolution of late stage diagenetic fabrics or the dissolution developed along late stage diagenetic fabrics (such as atylotea and fractures), 2. The dissolution pores filled with hydrocarbon or other late stage diagenetic minerals; 3. Not only the rnvered region, but also the Kepin outcrop region (continuous depression in early stage一from Cambrian to early Permian, uplift in late stage一from late Permian to present) have above charac- teristics. Based on preliminary analysis, this paper considers that the deep dissolution is mainly related to Co2-bearing acid water produced by organic matter thermal evolution of source rock.
1994, 12(1): 89-97.
Abstract:
The studied area is located in the eastern part of the North Qilian Caledonian foldbelt where the Carboniferous system with rich paleontological fossils develops perfectly and outcrops well.and the studies of the biostratigraphy have a long history. The two-fold division scheme for Carboniferous is adopted in this paper,i. e.,the Lower Carboniferous Series is composed of Qianheishan,Chouniukou and Tsingyuan Formations;and Upper one consists of Hong-tuwa,Yanghukou and Taiyuan Formations. The Qianheishan formation is equal to Tournaisian,Chouniukou to Visean,Tsingyuan and Hongtuwa to Namurian,Yanghukou and Taiyuan to Westphalian and Stephanian respectively. The evolution of the Carboniferous lithofacics and palcogography is described as follows: 1. This area was an epicontinental sea characterized by gulf. To the north was old Alaxa land;to the South Longxi uplift of Ordos. 2. During the Qianheishan-Tsingyuan period,the marine water invaded the area from Qinling through the Tianshui-Jingning strait,mak ing lion of this area became progressive it a gulf in the shape of“ overlap regulary. resultin;in the Hongtuw8-Westphalian,the invan developing a“Stephanian,the sea water expanded from North China into North Qilian,and conjoined Tianshan seas respectively shaped”gulf. In the with South China and 3. The coal-bearing alternative marine-continental facies of barrier coast consists mainly of elastic rocks and the region is composed of the plain facics zones of delta and seashore. The Lower Carboniferous contains gypsum. Although the fauna realm of the Visean,Namurian and Westphalian is similar to that of Euramerian,the sedimentary association is of the Qilian type. Taiyuan Formation belongs to the North China type charactcriccd by the Early Cathaysian flora. 4. Based on both the paleomagnetism and the paleoecology,this area was situated in the low latitudal zone in the Carboniferous period. It changed from the dry-hot in Tournaisian into damp-hot climate in the rest of the Carboniferous period. The Stcphanian stage is a main coal-forming period in this area. This area,the northern margin of Gansu-Qinghai-Tibet plate,acted as an ocean during the Early Paleozoic Era. The ancient oceanic crust should be subducted beneath the Center Qilian,and then,the collision between the Alaxa-Tarim and Caidam took place in the Caledonian,finally,resulting in the forming of the Hcxi-Corridor transitional }onc and the Caledonian foldbelt of the North Qilian. After that,the historical geology of Carboniferous in this area began to develop in the continental crust.
The studied area is located in the eastern part of the North Qilian Caledonian foldbelt where the Carboniferous system with rich paleontological fossils develops perfectly and outcrops well.and the studies of the biostratigraphy have a long history. The two-fold division scheme for Carboniferous is adopted in this paper,i. e.,the Lower Carboniferous Series is composed of Qianheishan,Chouniukou and Tsingyuan Formations;and Upper one consists of Hong-tuwa,Yanghukou and Taiyuan Formations. The Qianheishan formation is equal to Tournaisian,Chouniukou to Visean,Tsingyuan and Hongtuwa to Namurian,Yanghukou and Taiyuan to Westphalian and Stephanian respectively. The evolution of the Carboniferous lithofacics and palcogography is described as follows: 1. This area was an epicontinental sea characterized by gulf. To the north was old Alaxa land;to the South Longxi uplift of Ordos. 2. During the Qianheishan-Tsingyuan period,the marine water invaded the area from Qinling through the Tianshui-Jingning strait,mak ing lion of this area became progressive it a gulf in the shape of“ overlap regulary. resultin;in the Hongtuw8-Westphalian,the invan developing a“Stephanian,the sea water expanded from North China into North Qilian,and conjoined Tianshan seas respectively shaped”gulf. In the with South China and 3. The coal-bearing alternative marine-continental facies of barrier coast consists mainly of elastic rocks and the region is composed of the plain facics zones of delta and seashore. The Lower Carboniferous contains gypsum. Although the fauna realm of the Visean,Namurian and Westphalian is similar to that of Euramerian,the sedimentary association is of the Qilian type. Taiyuan Formation belongs to the North China type charactcriccd by the Early Cathaysian flora. 4. Based on both the paleomagnetism and the paleoecology,this area was situated in the low latitudal zone in the Carboniferous period. It changed from the dry-hot in Tournaisian into damp-hot climate in the rest of the Carboniferous period. The Stcphanian stage is a main coal-forming period in this area. This area,the northern margin of Gansu-Qinghai-Tibet plate,acted as an ocean during the Early Paleozoic Era. The ancient oceanic crust should be subducted beneath the Center Qilian,and then,the collision between the Alaxa-Tarim and Caidam took place in the Caledonian,finally,resulting in the forming of the Hcxi-Corridor transitional }onc and the Caledonian foldbelt of the North Qilian. After that,the historical geology of Carboniferous in this area began to develop in the continental crust.
1994, 12(1): 106-111.
Abstract:
There is a suit fine grain black rocks,Middle Ordivician,in central Hunan province, including black shale,banded silt一shale,mudstone and siliceous shale (sillcalite) and so on. They were formed at slope一 basin facies zone,and they high characters of REE geochemistry such as:high abundance of REE (FREE 271. 7ppm ),high ratio of ELREE/EHREE, La/Yb, (La/Yb)n,δCe value, and low bEu value. The REE patterns are comparcd to sediments of passive contnental margin region. Because of affecting sub-sedimentary environment,the sediments of background passive continental margin in the studied area are not only bigger δCe value,but also higher abundance of REE. Other sedimentary data demonstrated that they are products of anoxic environment at studied area. but they aren't appeared bigger δCe negative anomaly on the model curve of REE distribution. So δCe value cannot be take as indicator of anoxic environment. This paper discusses the tectonic background,the relationship bCe value between anoxic event and manganese origin,mudstone REE abundance and so on. It is made intelligible characteristics and distribution of REE anoxic down一warping basin of passive continental margin region.
There is a suit fine grain black rocks,Middle Ordivician,in central Hunan province, including black shale,banded silt一shale,mudstone and siliceous shale (sillcalite) and so on. They were formed at slope一 basin facies zone,and they high characters of REE geochemistry such as:high abundance of REE (FREE 271. 7ppm ),high ratio of ELREE/EHREE, La/Yb, (La/Yb)n,δCe value, and low bEu value. The REE patterns are comparcd to sediments of passive contnental margin region. Because of affecting sub-sedimentary environment,the sediments of background passive continental margin in the studied area are not only bigger δCe value,but also higher abundance of REE. Other sedimentary data demonstrated that they are products of anoxic environment at studied area. but they aren't appeared bigger δCe negative anomaly on the model curve of REE distribution. So δCe value cannot be take as indicator of anoxic environment. This paper discusses the tectonic background,the relationship bCe value between anoxic event and manganese origin,mudstone REE abundance and so on. It is made intelligible characteristics and distribution of REE anoxic down一warping basin of passive continental margin region.
1994, 12(1): 117-121.
Abstract:
Ulexite is a kind of mineral containing Na, Ca and crystalline water borate. It has been obtained from the borate deposits of Da一Chaidan and Xiao一Chaidan salt lakes in Qinghai and Z.azangzaka salt lake in TI- betan. After purification of the two samples,the contents of Na+,Ca++,B2O2 and H2O of ulexites were determined. They are in line with the chemical fromulae (2Ca0 2Na2O.5B202,.16H20). The results show that the samples are better than the ulexite reported by China. American and Russia in references. The physleal-chemical characteristics of ulexite have been, studied by X一ray powder differaction,IRspectrasopy. thermoanalysis methods,photomicro一graph and conventional chemical analysis. The results are comparatively systematical and satisfactory. The structure characteristics of ulexite in two regoin determined by X一ray powder differation are all completely agreed with standard card of JCPDS of ulexite. In the IR一spectra of the ulexite,there are four absorption peaks at 3220. 3320. 3420 and 3520 cm-1.They may be due to the bonding vibration of OH in crystalline water. In the 1500-400 cm-1region absorplion peaks are those of polyanion of borate. The asymmetric vibration of BO3-3. the bending vibration In the area of M一OH。the asymmetric vibration of BO4-1, the symmetric vibration of BO3-3. BO4-1. the bending vibration of BO3-3 and BO4-1. Those spectra show that the ulexite has two different type stracture of triganle BO3-3tetrahedra BO4-1. The crystal structure of ulexite is tricline, we also gave reflective index Ng=1. 517. Nm=1. 505. Np=1. 498 The two samples of Qlnghai and Tibetan are completely the same. The photoicrograph shows that they are needle一like crystals. Thermal behavior of the ulexites has been studied by DSC and DTA. Three endothermic peaks on the curve, they are dehydration crystall water. The endothermic peak at 800℃ is the rearrangement of polyborate molecule. The self-melt peak appears at 900℃. The first suggested solubilities of ulexite in the water at different temperature 3. 45. 3. 91,4. 25. 5. 00.5. 44 and 5. 95 g/1 at 10. 15. 20. 25, 30 and 35 respectively. The calculated values of enthapy of solution and entropy of solution.
Ulexite is a kind of mineral containing Na, Ca and crystalline water borate. It has been obtained from the borate deposits of Da一Chaidan and Xiao一Chaidan salt lakes in Qinghai and Z.azangzaka salt lake in TI- betan. After purification of the two samples,the contents of Na+,Ca++,B2O2 and H2O of ulexites were determined. They are in line with the chemical fromulae (2Ca0 2Na2O.5B202,.16H20). The results show that the samples are better than the ulexite reported by China. American and Russia in references. The physleal-chemical characteristics of ulexite have been, studied by X一ray powder differaction,IRspectrasopy. thermoanalysis methods,photomicro一graph and conventional chemical analysis. The results are comparatively systematical and satisfactory. The structure characteristics of ulexite in two regoin determined by X一ray powder differation are all completely agreed with standard card of JCPDS of ulexite. In the IR一spectra of the ulexite,there are four absorption peaks at 3220. 3320. 3420 and 3520 cm-1.They may be due to the bonding vibration of OH in crystalline water. In the 1500-400 cm-1region absorplion peaks are those of polyanion of borate. The asymmetric vibration of BO3-3. the bending vibration In the area of M一OH。the asymmetric vibration of BO4-1, the symmetric vibration of BO3-3. BO4-1. the bending vibration of BO3-3 and BO4-1. Those spectra show that the ulexite has two different type stracture of triganle BO3-3tetrahedra BO4-1. The crystal structure of ulexite is tricline, we also gave reflective index Ng=1. 517. Nm=1. 505. Np=1. 498 The two samples of Qlnghai and Tibetan are completely the same. The photoicrograph shows that they are needle一like crystals. Thermal behavior of the ulexites has been studied by DSC and DTA. Three endothermic peaks on the curve, they are dehydration crystall water. The endothermic peak at 800℃ is the rearrangement of polyborate molecule. The self-melt peak appears at 900℃. The first suggested solubilities of ulexite in the water at different temperature 3. 45. 3. 91,4. 25. 5. 00.5. 44 and 5. 95 g/1 at 10. 15. 20. 25, 30 and 35 respectively. The calculated values of enthapy of solution and entropy of solution.
