1995 Vol. 13, No. S1
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Display Method:
1995, 13(S1): 1-9.
Abstract:
The Huanglong Formation, Upper Carboniferous (corresponding to Kinderscoutian-Marsdenian Stage), is one of the most important natural gas reservoirs in Eastern Sichuan. According to the data of rock cores, well logging interpretations and seismic sections, etc., it is considered as a bype I carbonate sequence stratigraphy. The emphasis of this paper is focused on in the distinguishing features of sequences surf actes (such as, SBI. TS. MFS),order dividing or consociation of high-frequency cyclic sequences, sea-level changes and rate of deposition or basin tectonic sinking, etc,. In the formation, there are three cyclic orders can be recognized, which are 48-52 sixth-order.22 fifth-order. 8 fourth-order high -frequency cyclic sequences and 3 megacycles. The sixth-order cyclic sequences were the products of precession Milankovitch rhythms with a time duration of 0. 02 Ma, which were related to high-frequency cyclic sea-evel changes resulted from the Milankovitch cycle. The fifth-order cyclic sequences composed of 2-4 sixth-order cyclic sequences, which were corresponded to the parasequences and may be assigned to three cyclic types,including retrograda tional、aggradational and progradational parasequeces.The fourt h-order cyclic sequences were consisted of 2-4 fifth-order cyclic sequences, which were corresponded to the paasequence sets,developed shallowing-upward sedimentary sequence and bounded by the marine-flooding surface at base or exposure at top of each sequence. These ones may be divided into three genetic types,too,such as retrogradtional-aggradational parasequence sets、retrogradational-aggradational-progradational parasequence sets and aggradational-progradational parasequence sets. According to the association analysis. of the parasiquence sets, these 8 fourth-order cyclic sequences made up of 3 different megacyclic sequences: retrogradational-aggradational megacycle-lowstand systems tract, which was developed in low-part of the formation (C2h1) and bounded by SBI at the base ; retrogradational-aggradational-progradational megacycel-transgressive systems tract, which was developed in middle-part of the formation (C2h2) and bounded by TS1 at the base; aggradational-progradational megacycle -earlier deposition of highstand systems tract which was developed in upper-part of the formation (C2h3) and bounded by MFS at the base and SBI at the top. These megacyclic sequences constituted the low-frequency third-order cyClic depositional sequence in vertical section of the formation, where the later deposition of the highstand systems tract had been eroded by paleokarst during middler-later epoch, Late Carboniferous. It can be estimated, from the rusults above mentioned, that the age of the formation was about 0. 96-1. 04Ma, the sea-level changes were about 3.5 4. 0↓↑(LST) .4. 5-5. 0↑t (TST) anand6. 0-6. 5in 4 (HST) .the depositional rate were about 6. 8-7. 9cm/ Ka (LST).8. 7-10. 4cm/Ka (TST) and 6. 9-9. 9cm/Ka (earlier HST), and the basin tectonic sinking rate was about 7-8cm/Ka. All these evidences suggested that the Huanglong Formation, Upper Carboniferous deputed a carbonate sequence stratigraphy model of shallow stable intracratonic basin.
The Huanglong Formation, Upper Carboniferous (corresponding to Kinderscoutian-Marsdenian Stage), is one of the most important natural gas reservoirs in Eastern Sichuan. According to the data of rock cores, well logging interpretations and seismic sections, etc., it is considered as a bype I carbonate sequence stratigraphy. The emphasis of this paper is focused on in the distinguishing features of sequences surf actes (such as, SBI. TS. MFS),order dividing or consociation of high-frequency cyclic sequences, sea-level changes and rate of deposition or basin tectonic sinking, etc,. In the formation, there are three cyclic orders can be recognized, which are 48-52 sixth-order.22 fifth-order. 8 fourth-order high -frequency cyclic sequences and 3 megacycles. The sixth-order cyclic sequences were the products of precession Milankovitch rhythms with a time duration of 0. 02 Ma, which were related to high-frequency cyclic sea-evel changes resulted from the Milankovitch cycle. The fifth-order cyclic sequences composed of 2-4 sixth-order cyclic sequences, which were corresponded to the parasequences and may be assigned to three cyclic types,including retrograda tional、aggradational and progradational parasequeces.The fourt h-order cyclic sequences were consisted of 2-4 fifth-order cyclic sequences, which were corresponded to the paasequence sets,developed shallowing-upward sedimentary sequence and bounded by the marine-flooding surface at base or exposure at top of each sequence. These ones may be divided into three genetic types,too,such as retrogradtional-aggradational parasequence sets、retrogradational-aggradational-progradational parasequence sets and aggradational-progradational parasequence sets. According to the association analysis. of the parasiquence sets, these 8 fourth-order cyclic sequences made up of 3 different megacyclic sequences: retrogradational-aggradational megacycle-lowstand systems tract, which was developed in low-part of the formation (C2h1) and bounded by SBI at the base ; retrogradational-aggradational-progradational megacycel-transgressive systems tract, which was developed in middle-part of the formation (C2h2) and bounded by TS1 at the base; aggradational-progradational megacycle -earlier deposition of highstand systems tract which was developed in upper-part of the formation (C2h3) and bounded by MFS at the base and SBI at the top. These megacyclic sequences constituted the low-frequency third-order cyClic depositional sequence in vertical section of the formation, where the later deposition of the highstand systems tract had been eroded by paleokarst during middler-later epoch, Late Carboniferous. It can be estimated, from the rusults above mentioned, that the age of the formation was about 0. 96-1. 04Ma, the sea-level changes were about 3.5 4. 0↓↑(LST) .4. 5-5. 0↑t (TST) anand6. 0-6. 5in 4 (HST) .the depositional rate were about 6. 8-7. 9cm/ Ka (LST).8. 7-10. 4cm/Ka (TST) and 6. 9-9. 9cm/Ka (earlier HST), and the basin tectonic sinking rate was about 7-8cm/Ka. All these evidences suggested that the Huanglong Formation, Upper Carboniferous deputed a carbonate sequence stratigraphy model of shallow stable intracratonic basin.
1995, 13(S1): 27-37.
Abstract:
The sedimentary cycle in the middle and upper Eocene of Dongying basin is distinguished into five subsequences (DSI -DS5), six types of depositional systems and eleven factes, and divided into three evolution periods from bottom to top.Carbonatite system is extensively developed in the salt lake period (DS1) ; All types of sedimentary systems in the salt and deep lake period (DS2-DS3), however, lacustrine and gravity flow systems is mainly developed ; Delta and fluvial systems in fresh and shallow lake period (DS4-DS5).Sediments in gentle slope is thin, evolving from carbonatite to littoral-shallow lacustrine and fluvial factes sandstones. Sediments in steep slope is thick, evolving from pluvial fan factes sandy conglomerate to delta factes and braided delta factes sandstones. It represent asymmetry of the filling and evolution of the halfgraben basin. The delta system developed along the axis of the basin and prograded basinwards,resulting in the migration of the depocentre from east to west and forming main basin filling.
The sedimentary cycle in the middle and upper Eocene of Dongying basin is distinguished into five subsequences (DSI -DS5), six types of depositional systems and eleven factes, and divided into three evolution periods from bottom to top.Carbonatite system is extensively developed in the salt lake period (DS1) ; All types of sedimentary systems in the salt and deep lake period (DS2-DS3), however, lacustrine and gravity flow systems is mainly developed ; Delta and fluvial systems in fresh and shallow lake period (DS4-DS5).Sediments in gentle slope is thin, evolving from carbonatite to littoral-shallow lacustrine and fluvial factes sandstones. Sediments in steep slope is thick, evolving from pluvial fan factes sandy conglomerate to delta factes and braided delta factes sandstones. It represent asymmetry of the filling and evolution of the halfgraben basin. The delta system developed along the axis of the basin and prograded basinwards,resulting in the migration of the depocentre from east to west and forming main basin filling.
1995, 13(S1): 53-62.
Abstract:
The studied well of S113 is situated on the Sanzhao downwarp of the Songliao Basin. About 500m core sequences containing evaporite of Quantou formation (Albian) in the well were systematicly researched and described in their sedimentary sequences,structural and fabric features, mineral associations, as well as elemental geochemical and isotopic characteristics.According to the above studies,the authors concluded as following:1. The evaporites which are mainly anhydrite,barite as well as celestine and gypsum have two kinds of mineral associations and the cementation order of the minerals ought to be ba rite →calcite→celestine and calcite →gypsum (anhydrite) respectively, which agree with their solubilities.2. The palaeoenvironmental conditions were PH=9, Eh=0. 1, SO42- = 3084mg/L and CO32-= 102mg/L,which were the contents in between playa-lake and marine water.3. There were two sources for forming evaporites-episodical marine water input and continental sources which were mainly composed of meteoric water and oxidation of pyrite from C-P shales and Yanshanian igneous rocks.The ratio of volume of marine input to volume of continental input lay between 0: 12. 6: 1. 4. The marine water input became significant approximatly during the period of 102Ma,106Ma and 107Ma, which agree with the Mid-late Albian eustasy.5. Formed in the arid playa mud flat or salina, the evaporites deposited near water table. And the eolian effect could occasionally become significant.
The studied well of S113 is situated on the Sanzhao downwarp of the Songliao Basin. About 500m core sequences containing evaporite of Quantou formation (Albian) in the well were systematicly researched and described in their sedimentary sequences,structural and fabric features, mineral associations, as well as elemental geochemical and isotopic characteristics.According to the above studies,the authors concluded as following:1. The evaporites which are mainly anhydrite,barite as well as celestine and gypsum have two kinds of mineral associations and the cementation order of the minerals ought to be ba rite →calcite→celestine and calcite →gypsum (anhydrite) respectively, which agree with their solubilities.2. The palaeoenvironmental conditions were PH=9, Eh=0. 1, SO42- = 3084mg/L and CO32-= 102mg/L,which were the contents in between playa-lake and marine water.3. There were two sources for forming evaporites-episodical marine water input and continental sources which were mainly composed of meteoric water and oxidation of pyrite from C-P shales and Yanshanian igneous rocks.The ratio of volume of marine input to volume of continental input lay between 0: 12. 6: 1. 4. The marine water input became significant approximatly during the period of 102Ma,106Ma and 107Ma, which agree with the Mid-late Albian eustasy.5. Formed in the arid playa mud flat or salina, the evaporites deposited near water table. And the eolian effect could occasionally become significant.
1995, 13(S1): 71-78.
Abstract:
Tidalites in Zhejiang Ordovician System and the recent and subrecent tidal flat deposits in the Yangtze delta are studied,utilizing the method commonly-used abaord for tide-channel and tide-flat research.The tide-flat laminae and micro-sequences are measured, and the results are analyzed by time-series analytical method to achieve "spring-neap tidal cycles". Consequently, the sedimention rate on the tidal flats is calculated to be 3. 0-4. 5m/a. However, the sedimention rate, speculated from the sea-walls built in various ages in the Yangtze Delta and measured by Ph21o, is only 2. 2-4. 0cm/a. The former is approximately one hundred times greater than the latter.Sedimentary observation on modern tidal flat show that, laminae and micro-sequences are formed by changing of current velosity during single tidal cycle; whereas, single layer and small-sequences in tidal flat sediments are the results of the intercourse of storm and calm weathers. The laminae can be eroded and destroyed by ensuing strong tidal currents,and the small-sequences can be reworked by ensuing strong storm waves. Statistical data show that the number of preserved laminae and micro-sequences is less than 10% of the experienced cycles; and the nmuber of the preserved single layer and small-sequences is less than 10% of the experienced storms. This asymmetry betweent the preserved rhythms and the cycles of the affecting factors in the basic reason for the error in speculating sedimentary rates from the sedimention rhythms on the tidal flats.Sedimentation on tidal flats in mainly vertical aggradation, while in tidal channels is mainly lateral deposition. Erosion can eliminate the tide-flat rhythms. However, the tide-channel rhythms can be eroded also, but the number of the rhythms remains unchanged. Therefore, the method of calculating sedimentation duration and sedimention rate,developed from the concepts of the "tidal bundle" and "spring-neap tidal cycle" in tidal channels, is inapplicable to tidal flat sediments.
Tidalites in Zhejiang Ordovician System and the recent and subrecent tidal flat deposits in the Yangtze delta are studied,utilizing the method commonly-used abaord for tide-channel and tide-flat research.The tide-flat laminae and micro-sequences are measured, and the results are analyzed by time-series analytical method to achieve "spring-neap tidal cycles". Consequently, the sedimention rate on the tidal flats is calculated to be 3. 0-4. 5m/a. However, the sedimention rate, speculated from the sea-walls built in various ages in the Yangtze Delta and measured by Ph21o, is only 2. 2-4. 0cm/a. The former is approximately one hundred times greater than the latter.Sedimentary observation on modern tidal flat show that, laminae and micro-sequences are formed by changing of current velosity during single tidal cycle; whereas, single layer and small-sequences in tidal flat sediments are the results of the intercourse of storm and calm weathers. The laminae can be eroded and destroyed by ensuing strong tidal currents,and the small-sequences can be reworked by ensuing strong storm waves. Statistical data show that the number of preserved laminae and micro-sequences is less than 10% of the experienced cycles; and the nmuber of the preserved single layer and small-sequences is less than 10% of the experienced storms. This asymmetry betweent the preserved rhythms and the cycles of the affecting factors in the basic reason for the error in speculating sedimentary rates from the sedimention rhythms on the tidal flats.Sedimentation on tidal flats in mainly vertical aggradation, while in tidal channels is mainly lateral deposition. Erosion can eliminate the tide-flat rhythms. However, the tide-channel rhythms can be eroded also, but the number of the rhythms remains unchanged. Therefore, the method of calculating sedimentation duration and sedimention rate,developed from the concepts of the "tidal bundle" and "spring-neap tidal cycle" in tidal channels, is inapplicable to tidal flat sediments.
1995, 13(S1): 88-95.
Abstract:
The highest marine sediments discovered in Xizang untill now are the lower Tertary Eocene, among them the marine Eocene with better developed stratigraphic sequence is exposed in Gamba of south Xizang and was studied in detail. According to the foraminifera assemblage the upper member of Zhepure Formation may reach to early Late Eocene.The lower member of Zhepure Formation in study site is composed of bioclastic limestone, characterized by abundant large benthic foraminifera and calcareous algae. The lower member of the formation is mainly calcareous mudstone and silt. Based on the rock composition, texture and fossil of the limestone in Zhepure Formation, 8 micro factes are classified: bioclastic oolitic grainstone (MFI), oolitic bioclastic grainstone (MF2), sandy bioclastic oolitic grainstone (MF3), bioclastic packstone (MF4), bioclastic wackestone (MFS), bioclastic mudstone (MF6), muddy mudstone (MF7) and bioclastic marl (MFS). On the basis of factes analysis, it is inferred that Zhepure Formation formed in coastal-neritic environments including: (1 ) intertidal shoal environment, (2) subtidal shallow water environment, and (3) subtidal deeper water environment. The depositional environments changed obviously from the early Eocene carbanate depositional environments to terrigenous elastics lagoon environments where seawater might freshen slightly from the begining of late Eocene.It is considered in the present literatures that the Eocene marine sediments formed in the remnant ocean basin under the background of collision between india plate and Eurasian plate. But it is shown that the remnant ocean basin is connected to the open Tethys Ocean, which belongs to open remnant ocean basin type on the studies of limestone microfacies and fauna of Zhepure Formation. The basin might be somewhat isolated from open ocean in late Early Eocene. Some sketchs of continent and ocean distribution were made on the distribution of the Eocene marine strata in Xizang. However, it is mentioned in the paper that the reconstruction of the paleo-oceanographic limits should taken the consideration of ennuence of the nappe structure because of the complex imbricate thrust.
The highest marine sediments discovered in Xizang untill now are the lower Tertary Eocene, among them the marine Eocene with better developed stratigraphic sequence is exposed in Gamba of south Xizang and was studied in detail. According to the foraminifera assemblage the upper member of Zhepure Formation may reach to early Late Eocene.The lower member of Zhepure Formation in study site is composed of bioclastic limestone, characterized by abundant large benthic foraminifera and calcareous algae. The lower member of the formation is mainly calcareous mudstone and silt. Based on the rock composition, texture and fossil of the limestone in Zhepure Formation, 8 micro factes are classified: bioclastic oolitic grainstone (MFI), oolitic bioclastic grainstone (MF2), sandy bioclastic oolitic grainstone (MF3), bioclastic packstone (MF4), bioclastic wackestone (MFS), bioclastic mudstone (MF6), muddy mudstone (MF7) and bioclastic marl (MFS). On the basis of factes analysis, it is inferred that Zhepure Formation formed in coastal-neritic environments including: (1 ) intertidal shoal environment, (2) subtidal shallow water environment, and (3) subtidal deeper water environment. The depositional environments changed obviously from the early Eocene carbanate depositional environments to terrigenous elastics lagoon environments where seawater might freshen slightly from the begining of late Eocene.It is considered in the present literatures that the Eocene marine sediments formed in the remnant ocean basin under the background of collision between india plate and Eurasian plate. But it is shown that the remnant ocean basin is connected to the open Tethys Ocean, which belongs to open remnant ocean basin type on the studies of limestone microfacies and fauna of Zhepure Formation. The basin might be somewhat isolated from open ocean in late Early Eocene. Some sketchs of continent and ocean distribution were made on the distribution of the Eocene marine strata in Xizang. However, it is mentioned in the paper that the reconstruction of the paleo-oceanographic limits should taken the consideration of ennuence of the nappe structure because of the complex imbricate thrust.
1995, 13(S1): 102-108.
Abstract:
The Tiandong gas region is of a rich ore discovered in East Sichuan (Chuandong) since recent years, that has a good accumulative condition, high productivity, not wholly controlled by structural trap for gas enrichment. Through research,it is discovered that gas enrichment is mainly controlled by Kaijiang-Liangping paleo-uplift. Which has formed not only a series of composite trap of stratigraphy and structure, and also promoted the still more development of the effective thickness and pores of Carboniferous reservoir resulting in better accumulative condition on the basis of Carboniferous sedimentation factes and diagenesis of this region, beneficial to the development of pores. Secondly, it is situated within the low synclinores between two high and steep anticlines of Datianchi and Nanmenchang; the structural position is low.,and the trap is mostly adjacent to broad syncline which has not only the performance of preferentially accumulating the upmigrating gas from the underlying Silurian gas-origin layer, but also has a large area of controlling oil and gas enrichment,abundant gas-source, and high filling degree for the trap. Lastly, the paper has concisely commented the gas-bearing conditions of various traps.
The Tiandong gas region is of a rich ore discovered in East Sichuan (Chuandong) since recent years, that has a good accumulative condition, high productivity, not wholly controlled by structural trap for gas enrichment. Through research,it is discovered that gas enrichment is mainly controlled by Kaijiang-Liangping paleo-uplift. Which has formed not only a series of composite trap of stratigraphy and structure, and also promoted the still more development of the effective thickness and pores of Carboniferous reservoir resulting in better accumulative condition on the basis of Carboniferous sedimentation factes and diagenesis of this region, beneficial to the development of pores. Secondly, it is situated within the low synclinores between two high and steep anticlines of Datianchi and Nanmenchang; the structural position is low.,and the trap is mostly adjacent to broad syncline which has not only the performance of preferentially accumulating the upmigrating gas from the underlying Silurian gas-origin layer, but also has a large area of controlling oil and gas enrichment,abundant gas-source, and high filling degree for the trap. Lastly, the paper has concisely commented the gas-bearing conditions of various traps.
1995, 13(S1): 118-123.
Abstract:
The free hydrocarbons and vacuum pyrolyzed hydrocarbons of B. subtilis were analyzed by GC and GCMS system. The gas generation rate in B.subtilis during thermal degradation was high (67. 8ml/g), the ratio of normal and isomeric alkanes was low, and that of ethane to ethylene was high. The content of cholroform extractable organic matter increased by 9. 74 times after thermal degradation. The free hydrocarbons were mainly composed of C16-C30 n -alkanes with C27 as a main peak. The pyrolyzed hydrocarbons were mainly composed of C12-C20 branched-chain alkanes, C12-C25 n-alkanes and C15-C20, isoprenoid alkanes, with 3-Methyltridecane as a main peak, the content of C15 n-alkane was the highest among all n-alkanes.
The free hydrocarbons and vacuum pyrolyzed hydrocarbons of B. subtilis were analyzed by GC and GCMS system. The gas generation rate in B.subtilis during thermal degradation was high (67. 8ml/g), the ratio of normal and isomeric alkanes was low, and that of ethane to ethylene was high. The content of cholroform extractable organic matter increased by 9. 74 times after thermal degradation. The free hydrocarbons were mainly composed of C16-C30 n -alkanes with C27 as a main peak. The pyrolyzed hydrocarbons were mainly composed of C12-C20 branched-chain alkanes, C12-C25 n-alkanes and C15-C20, isoprenoid alkanes, with 3-Methyltridecane as a main peak, the content of C15 n-alkane was the highest among all n-alkanes.
GC-AED Measurement for Organic Sulphur Compounds and Its Tentative Applications in petroleum Geology
1995, 13(S1): 134-137.
Abstract:
Heterocyclic compounds (e. g., N,O,S compounds) have been arousing more and more attention in geochemical stydies. The conventional techniques for measurements of organic sulphur compounds are GC-MS and GC-FPD. But these are limited, at least to some degree, by specificity, sensitivity and co-elution. In the present study,GC-AED (Gas Chromatagraph with Atomatic Emission Detector) was applied to the measurement for organic sulphur compounds in oils from different sedimentary environments in China. The results show that the high specificity and sensitivitiy of the GC-AED make it advantageous in analyses for these heterocyclic compounds. There exists obvious difference in concentration and distribution of organic sulphur compounds among different sedimentary environments: Oils devived from marine carbonate often have a much more higher content of organic sulphur compounds than those from rocks of terrestrial fresh water and swamp depositional factes. This may be useful in oil-to-oil and oil-to-source correlations.
Heterocyclic compounds (e. g., N,O,S compounds) have been arousing more and more attention in geochemical stydies. The conventional techniques for measurements of organic sulphur compounds are GC-MS and GC-FPD. But these are limited, at least to some degree, by specificity, sensitivity and co-elution. In the present study,GC-AED (Gas Chromatagraph with Atomatic Emission Detector) was applied to the measurement for organic sulphur compounds in oils from different sedimentary environments in China. The results show that the high specificity and sensitivitiy of the GC-AED make it advantageous in analyses for these heterocyclic compounds. There exists obvious difference in concentration and distribution of organic sulphur compounds among different sedimentary environments: Oils devived from marine carbonate often have a much more higher content of organic sulphur compounds than those from rocks of terrestrial fresh water and swamp depositional factes. This may be useful in oil-to-oil and oil-to-source correlations.
1995, 13(S1): 147-150.
Abstract:
Based on results from thermal modelling experiments of kerogens,this paper presents a brief discussion on secondary generation of hydrocarbons. Geological effects, such as structural movement, etc.,may result in liftion or denudation of source rocks which do not enter highly-and post-mature phases, which causes the decrease of geotemperature of the source rocks and the cease of hydrocarbon generation. While the source rocks subside .again, the geotemperature increases, and when it reachs a certain point, the unexhaused kerogens may generate hydrocarbons again.The generated oil-gas amount with the continuous process of hydrocarbon generation is close to the total amounts of twice generations, indicating that hydrocarbon-generating amount is not affected by the secondary hydrocarbon generation that only defer generating oil and gas.
Based on results from thermal modelling experiments of kerogens,this paper presents a brief discussion on secondary generation of hydrocarbons. Geological effects, such as structural movement, etc.,may result in liftion or denudation of source rocks which do not enter highly-and post-mature phases, which causes the decrease of geotemperature of the source rocks and the cease of hydrocarbon generation. While the source rocks subside .again, the geotemperature increases, and when it reachs a certain point, the unexhaused kerogens may generate hydrocarbons again.The generated oil-gas amount with the continuous process of hydrocarbon generation is close to the total amounts of twice generations, indicating that hydrocarbon-generating amount is not affected by the secondary hydrocarbon generation that only defer generating oil and gas.
1995, 13(S1): 158-163.
Abstract:
It is realized that clay minerals in sandstone reservoir have important effect with the second, and the third exploitation of oil and gas fields. For instance, Kaolinite has the property of rapid flow, and montmorillonite of water-sensitive, illite of resistance, but chlorite has the property of acid-sensitive.They fill in the throats of pore through different ways and affect the beneficial result and the technology of oil and gas exploitation. These properties and the differences in composition and content of the clay minerals will influence the pores shape and percolating force, as well as the accurate appreciation of oil and gas resources. Therefore, a mathematical model that was built by using the composition, content, porosity and permeability of the clay minerals is adopted within this paper to evaluate the sandstone reservoir quantitatively. This method is called the evaluation of the secondary parameters of the clay minerals.
It is realized that clay minerals in sandstone reservoir have important effect with the second, and the third exploitation of oil and gas fields. For instance, Kaolinite has the property of rapid flow, and montmorillonite of water-sensitive, illite of resistance, but chlorite has the property of acid-sensitive.They fill in the throats of pore through different ways and affect the beneficial result and the technology of oil and gas exploitation. These properties and the differences in composition and content of the clay minerals will influence the pores shape and percolating force, as well as the accurate appreciation of oil and gas resources. Therefore, a mathematical model that was built by using the composition, content, porosity and permeability of the clay minerals is adopted within this paper to evaluate the sandstone reservoir quantitatively. This method is called the evaluation of the secondary parameters of the clay minerals.
1995, 13(S1): 171-175.
Abstract:
It has long been known that CO2, content of the atmosphere influences temperature by determining the amount of long-wave radiation trapped in the atmosphere. Therefore, Understanding the variation of atmospheric CO2 during Quaternary is very important for studying the influence of atmospheric CO2 on global climatic change. UP till now the information on variation of atmospheric CO2 during Quaternary is mainly obtained by the composition analysis of ice core.Because the longeSt cores so far obtained (1400-3000m) cover only the last 100000-160000 years, the studying on variation, of atmospheric CO2, during Quaternary is restricted.△C is a secondary carbonate in loess sediment with a characteristic thermo-decompositon interval(500600℃). The isotopic composition characteristics and geographical distributive feature of △C suggest that AC was formed under the condition of arid or semiarid, low temperatory, high evaporation and little vegetation. Under the condition loess CO2is mainly from atmosphere and its carbon isotopic composition is veryclose to that of atmospheric CO2.The relationship between CO2 content of the atmosphere and its carbon isotopic composition in northwest of China is δ13C=5756/[CO2]-22. 7Replacing δ13C of atmospheric CO2, with that of △C, we preliminaryly estimate the CO2 content of the paleo-atmosphere. The results show that the CO2content of the atmosphere from E1-1 to S3ranges from 311. 1 × 10-6 to 397. 0× 10-6and the difference between estimated values and measured values decreases with the climatic evolution from wet-warm to dry-cold.
It has long been known that CO2, content of the atmosphere influences temperature by determining the amount of long-wave radiation trapped in the atmosphere. Therefore, Understanding the variation of atmospheric CO2 during Quaternary is very important for studying the influence of atmospheric CO2 on global climatic change. UP till now the information on variation of atmospheric CO2 during Quaternary is mainly obtained by the composition analysis of ice core.Because the longeSt cores so far obtained (1400-3000m) cover only the last 100000-160000 years, the studying on variation, of atmospheric CO2, during Quaternary is restricted.△C is a secondary carbonate in loess sediment with a characteristic thermo-decompositon interval(500600℃). The isotopic composition characteristics and geographical distributive feature of △C suggest that AC was formed under the condition of arid or semiarid, low temperatory, high evaporation and little vegetation. Under the condition loess CO2is mainly from atmosphere and its carbon isotopic composition is veryclose to that of atmospheric CO2.The relationship between CO2 content of the atmosphere and its carbon isotopic composition in northwest of China is δ13C=5756/[CO2]-22. 7Replacing δ13C of atmospheric CO2, with that of △C, we preliminaryly estimate the CO2 content of the paleo-atmosphere. The results show that the CO2content of the atmosphere from E1-1 to S3ranges from 311. 1 × 10-6 to 397. 0× 10-6and the difference between estimated values and measured values decreases with the climatic evolution from wet-warm to dry-cold.
1995, 13(S1): 18-26.
Abstract:
Sequence stratigraphical analysis in epicontinental paralic coal measure is a new problem for study. Based on the sedimentary characteristics of Permo-carboniferous coal measure in Shandong and its adjacent area and the general feature of the vast coal-bearing depositional basin of North China,using the thought,method and techique of sequence stratigraphy originated from the study of marine basin, the authors have carried out the sequence stratigraphical analysis in paralic coal measure. Our research shows that the Late Paleozoic paralic coal measure in the study area can be divided into three third order sequences which are seperated by periodic surface of third order sea-level changes. The three boundaries of sequence are comformity planes in North China area. The basic architecture of the coal bearing sequences are characterized by dualistic pattern, which differs from the typical u lowstand-trausgressive-highstand "model established by North American scholars in the study of continental marginal oil-gas basin.The classfication of sequences, the identification and the follow-up correlation of various order surfaces of internal units in sequence have solved the confused correlation problem in the study of vertical succession.The correlating analysis of depositional systems, and system tracts, and the determination of the stratigraphical frame of coal bearing sequence provide the bases for the basin-filling analysis of the vast epicontinental basin. In this paper, the classification of parasequences and the characteristics of their boundaries are discussed. Research also shows that the transgressive systems tracts consist of I to 2 parasequences, and the highstand systems tracts are composed of 4 to 7 parasequences. Seventeen parasequences are distinguished in the three third-order sequences, most of them are of periodic parasequences. The classification of parasequences is dependent on the identification of regional transgressive boundaries. In the paralic coal measure developed in the epicontinental sea, the thin-layered stable transgressive beds,the extensively distributed tidal flat deopsits and peat swawp deposits provide correlation basis for the classification of parasequences.
Sequence stratigraphical analysis in epicontinental paralic coal measure is a new problem for study. Based on the sedimentary characteristics of Permo-carboniferous coal measure in Shandong and its adjacent area and the general feature of the vast coal-bearing depositional basin of North China,using the thought,method and techique of sequence stratigraphy originated from the study of marine basin, the authors have carried out the sequence stratigraphical analysis in paralic coal measure. Our research shows that the Late Paleozoic paralic coal measure in the study area can be divided into three third order sequences which are seperated by periodic surface of third order sea-level changes. The three boundaries of sequence are comformity planes in North China area. The basic architecture of the coal bearing sequences are characterized by dualistic pattern, which differs from the typical u lowstand-trausgressive-highstand "model established by North American scholars in the study of continental marginal oil-gas basin.The classfication of sequences, the identification and the follow-up correlation of various order surfaces of internal units in sequence have solved the confused correlation problem in the study of vertical succession.The correlating analysis of depositional systems, and system tracts, and the determination of the stratigraphical frame of coal bearing sequence provide the bases for the basin-filling analysis of the vast epicontinental basin. In this paper, the classification of parasequences and the characteristics of their boundaries are discussed. Research also shows that the transgressive systems tracts consist of I to 2 parasequences, and the highstand systems tracts are composed of 4 to 7 parasequences. Seventeen parasequences are distinguished in the three third-order sequences, most of them are of periodic parasequences. The classification of parasequences is dependent on the identification of regional transgressive boundaries. In the paralic coal measure developed in the epicontinental sea, the thin-layered stable transgressive beds,the extensively distributed tidal flat deopsits and peat swawp deposits provide correlation basis for the classification of parasequences.
1995, 13(S1): 38-46.
Abstract:
The study materials of this paper were collected from the Lower Carboniferous of Damusi section, Shache County, SW Tarim Basin. The hypothesis of Punctuated Aggradational CyCles sequences (Goodwin,P. W. Anderson, E. J., 1985) is applied to the analysis of the micro-strata of the Visean (Early Carboniferous) Heshilafu Formation. Five types micro-factes are also recognized from the above micro-strata.Based on the micro-factes and palaeoecological analysis, 71 PACs (Punctuated Aggradational Cycles sequence) are identified from the 2nd and 3rd Member of the Heshilafu Formation. Among them, 36 PACs recorded in the 2nd Member of the Heshilafu Formation form the Transgressive System Tracts (TST) and Highstand System Tracts (HST) of Sequence I, the other 35 PACs consist of Sequence II standing for the 3rd cycles. The above forcro-strata analysis indicates the characters of frequent high-frequency sea-level changes and cycles within cycles (Miall, A. D., 1985) in the southwestern sea of Tarim during Visean time.Those mutiple cycles can be classified to 4 orders cycles at least corresponding to 4 orders sea-level changes.The above 71 basic high-frequency cycles controlled by 11 fourth order cycles consist of two 3rd order cycles standing for sequences, which are also controlled by a 2nd order cycle standing for supersequence. Every high-frequency sea level rising corresponds to large diversity of brachiopods. The maxium flooding surface of depositional sequence corresponds to the greatest value of the diversity of brachiopods.
The study materials of this paper were collected from the Lower Carboniferous of Damusi section, Shache County, SW Tarim Basin. The hypothesis of Punctuated Aggradational CyCles sequences (Goodwin,P. W. Anderson, E. J., 1985) is applied to the analysis of the micro-strata of the Visean (Early Carboniferous) Heshilafu Formation. Five types micro-factes are also recognized from the above micro-strata.Based on the micro-factes and palaeoecological analysis, 71 PACs (Punctuated Aggradational Cycles sequence) are identified from the 2nd and 3rd Member of the Heshilafu Formation. Among them, 36 PACs recorded in the 2nd Member of the Heshilafu Formation form the Transgressive System Tracts (TST) and Highstand System Tracts (HST) of Sequence I, the other 35 PACs consist of Sequence II standing for the 3rd cycles. The above forcro-strata analysis indicates the characters of frequent high-frequency sea-level changes and cycles within cycles (Miall, A. D., 1985) in the southwestern sea of Tarim during Visean time.Those mutiple cycles can be classified to 4 orders cycles at least corresponding to 4 orders sea-level changes.The above 71 basic high-frequency cycles controlled by 11 fourth order cycles consist of two 3rd order cycles standing for sequences, which are also controlled by a 2nd order cycle standing for supersequence. Every high-frequency sea level rising corresponds to large diversity of brachiopods. The maxium flooding surface of depositional sequence corresponds to the greatest value of the diversity of brachiopods.
1995, 13(S1): 63-70.
Abstract:
The sandstones in Fu-yang Formations deposited by fluvial-lacustrine sedimentary system have more than 70 percent of unstable fragments such as feldspar and volcanic-rock fragments.Based on thin-section analysis,XRD, SEM, electronprobe and fluid inclusion analysis, the progressive diagenetic sequence for the sandstones could be summarized. But, the diagenetic property is also controlled by ①pore-water geochemistry,② burial depth and geothermal gradient, and ③sedimentary environments and so on, which caused the diagenetic environments fairyly different.The local hydrodynamic units, with different origins and compositions of pore-water, is the main factor, which controls the kinds of diagenetic factes. The planar delimitation lines of local hydrodynamic units are unanomalous with those of local porewater geochemistry units and diagenetic factes.In the study area, four types of diagenetic factes can be recognized: meteoric water infiltration diagenetic factes, burial water diagenetic factes, mixture water diagenetic factes and paleo-evaporation water diagenetic factes.
The sandstones in Fu-yang Formations deposited by fluvial-lacustrine sedimentary system have more than 70 percent of unstable fragments such as feldspar and volcanic-rock fragments.Based on thin-section analysis,XRD, SEM, electronprobe and fluid inclusion analysis, the progressive diagenetic sequence for the sandstones could be summarized. But, the diagenetic property is also controlled by ①pore-water geochemistry,② burial depth and geothermal gradient, and ③sedimentary environments and so on, which caused the diagenetic environments fairyly different.The local hydrodynamic units, with different origins and compositions of pore-water, is the main factor, which controls the kinds of diagenetic factes. The planar delimitation lines of local hydrodynamic units are unanomalous with those of local porewater geochemistry units and diagenetic factes.In the study area, four types of diagenetic factes can be recognized: meteoric water infiltration diagenetic factes, burial water diagenetic factes, mixture water diagenetic factes and paleo-evaporation water diagenetic factes.
1995, 13(S1): 79-87.
Abstract:
The first stiff clays at the Yangtze Delta are considered to be paleosols by their characteristics, such as plant debris and roots, clay-filled cracks, cutans, peds, and nodules, etc. It is learned from the clay contents, chemical and magnetic fabrics analyses that the stiff clays are complex polygenetic paleosols. The parent material of the paleosols are inferred to be alluvium based on the comparisons of their magnetic parameters with those of Xiashu Loess, Loess-Paleosol Series of Central China and tidal flat sediments of Shanghai.It is learned from the concentration of MnO2. nH2O that the depth of groundwater was about three meters, which was due to the higher elevation of this area during the period of glacial low stand of sea level.The well -developed and clay - filled cracks, along with the fluctuations of groundwater, indicate that the dry and wet seasons were distinctive and the effects of monsoon were stronger than nowadays.Paleosols are thicker than modern soils, and are thinner in the east than in the west of this area, which relates to the different time spans of pedogenesis caused by transgression and regression.
The first stiff clays at the Yangtze Delta are considered to be paleosols by their characteristics, such as plant debris and roots, clay-filled cracks, cutans, peds, and nodules, etc. It is learned from the clay contents, chemical and magnetic fabrics analyses that the stiff clays are complex polygenetic paleosols. The parent material of the paleosols are inferred to be alluvium based on the comparisons of their magnetic parameters with those of Xiashu Loess, Loess-Paleosol Series of Central China and tidal flat sediments of Shanghai.It is learned from the concentration of MnO2. nH2O that the depth of groundwater was about three meters, which was due to the higher elevation of this area during the period of glacial low stand of sea level.The well -developed and clay - filled cracks, along with the fluctuations of groundwater, indicate that the dry and wet seasons were distinctive and the effects of monsoon were stronger than nowadays.Paleosols are thicker than modern soils, and are thinner in the east than in the west of this area, which relates to the different time spans of pedogenesis caused by transgression and regression.
1995, 13(S1): 96-101.
Abstract:
There are lot of Tertiary lake sediments along the east part of China. Many of them are composed of muds and shales and have high oil-bearing potentialities. To understand the genesis of those sediments, a new magnetic method drawn from environmental magnetism has been introduced. Also, feasibility in applying it to research Tertiary lake sediments has been evaluated. We chose the Niu 38 core composed of red and grey muds and black shales from dingying Depression as research material. Susceptibility (Sus.) of those rocks has been measured. Heavy mineral analysis and total iron, reactive iron and total sulfur analyses of the controlling samples have been done to explain the causes of the Sus. properties in those sediments.From the profile of Sus., we can get three interesting facts: the first is that sediments with different colors, shes have their own special Sus. ; the second is that the change rythem of the Sus. is very clear and it can be divided into three main cycles from the bottom to the top; the third is that the Sus. profile is more sensible to the change of muds and shales than resistivity logs.Heavy mineral analysis shows that red muds with high Sus. are composed chiefly of haematites; grey muds with low Sus. contains less haematites and a bit of pyrites ; black shale with low Sus. mainly pyrites.DOP index suggests that the red muds formed under oxygen water and black shell in euxinic environment.Maeanwhile the grey muds form in a condition of high rate of sedimentation. So we can conclude that the shift of reactive iron to pyrites in the sediments under different redox conditions is the main controlling factor of change of Sus. Then the link between the change of Sus. in Tertiary sediments and their environmental significance can be set up. It is possible for us to predict sedimentary conditions through analyses of Sus. logs.
There are lot of Tertiary lake sediments along the east part of China. Many of them are composed of muds and shales and have high oil-bearing potentialities. To understand the genesis of those sediments, a new magnetic method drawn from environmental magnetism has been introduced. Also, feasibility in applying it to research Tertiary lake sediments has been evaluated. We chose the Niu 38 core composed of red and grey muds and black shales from dingying Depression as research material. Susceptibility (Sus.) of those rocks has been measured. Heavy mineral analysis and total iron, reactive iron and total sulfur analyses of the controlling samples have been done to explain the causes of the Sus. properties in those sediments.From the profile of Sus., we can get three interesting facts: the first is that sediments with different colors, shes have their own special Sus. ; the second is that the change rythem of the Sus. is very clear and it can be divided into three main cycles from the bottom to the top; the third is that the Sus. profile is more sensible to the change of muds and shales than resistivity logs.Heavy mineral analysis shows that red muds with high Sus. are composed chiefly of haematites; grey muds with low Sus. contains less haematites and a bit of pyrites ; black shale with low Sus. mainly pyrites.DOP index suggests that the red muds formed under oxygen water and black shell in euxinic environment.Maeanwhile the grey muds form in a condition of high rate of sedimentation. So we can conclude that the shift of reactive iron to pyrites in the sediments under different redox conditions is the main controlling factor of change of Sus. Then the link between the change of Sus. in Tertiary sediments and their environmental significance can be set up. It is possible for us to predict sedimentary conditions through analyses of Sus. logs.
1995, 13(S1): 109-117.
Abstract:
The 2-section of Jialingjang Group of Triassic in the eastern part of Sichuan Basin is an important gas bearing position. The Development of bank-micro factes have played an important pole in controlling the gas pool of fracture-pore type in traps.The banks are POint-bank on the platform in upper yangtze epicontinental sea. The new classificantion of shallow-sea bank and shallow exposed banks has been suggested on the basis of the evolution model of depositional environments which were controlled by relative sea-level changes. The similarities and difference of two types of banks have been compared. There were four bank development periods in the multicycle sedements of 2-section of Jialingjiang Group.The distribution of banks in two bank-development periods, for example, the 2-subsection of 2-section, have been mapped. The composition and devolopment model of point-bank at the Tishan anticline has been analysed. It clearly points out that the lithic factes in the core of bank have big thickness and good continuity in the multi-bank development periods. There are three types of factes sequences models:(1) the banks developed with sea-level up and disappeared with sea-level down; (2) the banks developed with sea-level down and disappeared to expose ; and (3) the banks developed with sea-level up and disappeared with sea-level up.Finally, the authors state how the shallow exposed bank control the formation of gas-pool. It has been recognind: ①the bank-microfacies complexs are beneficial for complexs of oil-producing, reservoir and seal formations, ②the shallow exposed bank is the microfacies zone of the pore-layers devolopment, ③ the sediment-diagenetic trap formed in bank-microfacies zone is beneficial for early accumulation of oil and gas pools @the development of pore-layers and accumulation of oil and gas in early sediment-diagenetic traps are the base of present gas -pool of fracture-pore type in various traps.
The 2-section of Jialingjang Group of Triassic in the eastern part of Sichuan Basin is an important gas bearing position. The Development of bank-micro factes have played an important pole in controlling the gas pool of fracture-pore type in traps.The banks are POint-bank on the platform in upper yangtze epicontinental sea. The new classificantion of shallow-sea bank and shallow exposed banks has been suggested on the basis of the evolution model of depositional environments which were controlled by relative sea-level changes. The similarities and difference of two types of banks have been compared. There were four bank development periods in the multicycle sedements of 2-section of Jialingjiang Group.The distribution of banks in two bank-development periods, for example, the 2-subsection of 2-section, have been mapped. The composition and devolopment model of point-bank at the Tishan anticline has been analysed. It clearly points out that the lithic factes in the core of bank have big thickness and good continuity in the multi-bank development periods. There are three types of factes sequences models:(1) the banks developed with sea-level up and disappeared with sea-level down; (2) the banks developed with sea-level down and disappeared to expose ; and (3) the banks developed with sea-level up and disappeared with sea-level up.Finally, the authors state how the shallow exposed bank control the formation of gas-pool. It has been recognind: ①the bank-microfacies complexs are beneficial for complexs of oil-producing, reservoir and seal formations, ②the shallow exposed bank is the microfacies zone of the pore-layers devolopment, ③ the sediment-diagenetic trap formed in bank-microfacies zone is beneficial for early accumulation of oil and gas pools @the development of pore-layers and accumulation of oil and gas in early sediment-diagenetic traps are the base of present gas -pool of fracture-pore type in various traps.
1995, 13(S1): 124-133.
Abstract:
Having investigated the detailed organic petrological characteristics of the marine hydrocarbon source rocks in the Tarim basin, the authors systematically elucidate the optical properties and origins of macerals occurring in these marine source rocks.Four new macerals have first been recognized in the source rocks,which are called as algobitumen, zobitumen, vitrinite-like macerals and marine inertinite. On the basis of this observation, a petrographic classification of macerals of the marine hydrocarbon source rocks in the Tarim basin has been suggested. This scheme is based on the research of the polished surfaces of the whole rocks and the thin sections of kerogen. The influence of maturity level on optical properties of macerals is emphasized in this scheme, so this classification scheme is also suitable to other marine hydrocarbon source rocks.
Having investigated the detailed organic petrological characteristics of the marine hydrocarbon source rocks in the Tarim basin, the authors systematically elucidate the optical properties and origins of macerals occurring in these marine source rocks.Four new macerals have first been recognized in the source rocks,which are called as algobitumen, zobitumen, vitrinite-like macerals and marine inertinite. On the basis of this observation, a petrographic classification of macerals of the marine hydrocarbon source rocks in the Tarim basin has been suggested. This scheme is based on the research of the polished surfaces of the whole rocks and the thin sections of kerogen. The influence of maturity level on optical properties of macerals is emphasized in this scheme, so this classification scheme is also suitable to other marine hydrocarbon source rocks.
1995, 13(S1): 138-146.
Abstract:
A series of aromatic des-A-triterpenoid hydrocarbons were identified in some Jurassic coals from the Turpan-Hami Basin. Their carbon numbers are of CＣ20 to Ｃ24, with molecular weights of 264￣320. These compounds are characterred by m+ -15 base peaks and same mass spectral fragments such as m/z 193, 195, 207,209, 178, 179, 181, 165, 155, 189, 191, 205, 102, 119, 55, 69, 83, 109 and 111. Based on mass spectral characteristics, cleavage mechanism analysis and comparison to the published mass spectra, these compounds are confirmed to be of structural skeleton of chrysenes ; with different amounts and positions of methyl groups;and with B- ring aromatized but C and D-ring containing one double-bond respectively.M+-15 base peaks are suggested to be caused by loss of C-14 methyl. These compounds are suggested to be derived mainly from highter plant 3-oxygenated pentacyclic triterpenoids (oleanane and ursane series)by photochemically and/or microbially mediated loss of ring A and subsequent aromatisations. Their identifications in the Jurassic coals may suggest that these compounds are derived not only from angiosperms but also from gymnosperms.
A series of aromatic des-A-triterpenoid hydrocarbons were identified in some Jurassic coals from the Turpan-Hami Basin. Their carbon numbers are of CＣ20 to Ｃ24, with molecular weights of 264￣320. These compounds are characterred by m+ -15 base peaks and same mass spectral fragments such as m/z 193, 195, 207,209, 178, 179, 181, 165, 155, 189, 191, 205, 102, 119, 55, 69, 83, 109 and 111. Based on mass spectral characteristics, cleavage mechanism analysis and comparison to the published mass spectra, these compounds are confirmed to be of structural skeleton of chrysenes ; with different amounts and positions of methyl groups;and with B- ring aromatized but C and D-ring containing one double-bond respectively.M+-15 base peaks are suggested to be caused by loss of C-14 methyl. These compounds are suggested to be derived mainly from highter plant 3-oxygenated pentacyclic triterpenoids (oleanane and ursane series)by photochemically and/or microbially mediated loss of ring A and subsequent aromatisations. Their identifications in the Jurassic coals may suggest that these compounds are derived not only from angiosperms but also from gymnosperms.
1995, 13(S1): 151-157.
Abstract:
This article inquires into the changes and composition of vertical and transverse (on land and in water) of fallout and flow detrital deposits of pyroclast sediment in the Datong volcano group. It was discovered that airfall deposits are vertically layered and that the grain size grade and thickness of the vertical accretion deposits L6gularly decreases in correspondence with the distance from the volcanic crater. In flow deposits,however, pumice grain size grade has the reverse relationship. Fine grain sediment generally form at very long distance from the volcano crater, but there are also fine grain deposits close to the crater. This variation.is related to the magnitude of the volcano's extrusive force. Therefore,while coarse grain fallout sediments is a reliable index of distance from the crater, fine grain sediments do not, however, necessarily indicate distance from the crater mouth.
This article inquires into the changes and composition of vertical and transverse (on land and in water) of fallout and flow detrital deposits of pyroclast sediment in the Datong volcano group. It was discovered that airfall deposits are vertically layered and that the grain size grade and thickness of the vertical accretion deposits L6gularly decreases in correspondence with the distance from the volcanic crater. In flow deposits,however, pumice grain size grade has the reverse relationship. Fine grain sediment generally form at very long distance from the volcano crater, but there are also fine grain deposits close to the crater. This variation.is related to the magnitude of the volcano's extrusive force. Therefore,while coarse grain fallout sediments is a reliable index of distance from the crater, fine grain sediments do not, however, necessarily indicate distance from the crater mouth.
1995, 13(S1): 164-170.
Abstract:
The study focuses on the Kalpin Region, where is of an arid climate, 40-80mm annual precipitation,sparse vegetation, and well exposed rocks. The strata of the study area are mainly composed of carbonates from littoral to shallow marine factes and elastics from marine-continent transitional to terrestrial factes.Based on the synthetical analysis of the characteristics of chemical and mineral composition, renectance specturm, and imagery brightness values of different rocks, the method for extracting the lithostratigraphic information from Landsat Thematic Mapper (TM) imagery has been approached.The results of reflectance spectrum measurement show that the absorption features of different rocks are all present from the electronic transitions and vibrations of the ferro ions, hydroxyl, molecular water, and carbonaceous ion in the constituent minerals. The results of X ray diffraction analysis and thin section identification show that the dinerals are mainly calcite,dolomite, chlorite, and hematite etc., and most of the minerals appear in the rocks as main component or impurity and cement. According to the spectral renectance features of the minerals, the authors pointed out that the band ratio images, such as TM3/1, TM2/3, TM4/3, and TM7/5, can extract the lithostratigraphic information of different rocks in the study area effectively.By analysing the imagery features of different rocks using a ratio colour composite image, which was superimposed on the TM4 single band image, the authors also presented the results of lithostratigraphic interpretation of the study area, which has shown a good potential for extracting lithostratigraphic information by using TM image data.
The study focuses on the Kalpin Region, where is of an arid climate, 40-80mm annual precipitation,sparse vegetation, and well exposed rocks. The strata of the study area are mainly composed of carbonates from littoral to shallow marine factes and elastics from marine-continent transitional to terrestrial factes.Based on the synthetical analysis of the characteristics of chemical and mineral composition, renectance specturm, and imagery brightness values of different rocks, the method for extracting the lithostratigraphic information from Landsat Thematic Mapper (TM) imagery has been approached.The results of reflectance spectrum measurement show that the absorption features of different rocks are all present from the electronic transitions and vibrations of the ferro ions, hydroxyl, molecular water, and carbonaceous ion in the constituent minerals. The results of X ray diffraction analysis and thin section identification show that the dinerals are mainly calcite,dolomite, chlorite, and hematite etc., and most of the minerals appear in the rocks as main component or impurity and cement. According to the spectral renectance features of the minerals, the authors pointed out that the band ratio images, such as TM3/1, TM2/3, TM4/3, and TM7/5, can extract the lithostratigraphic information of different rocks in the study area effectively.By analysing the imagery features of different rocks using a ratio colour composite image, which was superimposed on the TM4 single band image, the authors also presented the results of lithostratigraphic interpretation of the study area, which has shown a good potential for extracting lithostratigraphic information by using TM image data.
