1996 Vol. 14, No. 4
column
Display Method:
1996, 14(4): 24-30.
Abstract:
The vitrinite reflectance (R o) is related to its hydrocarbon generation ratio, therefore, the hydrocarbon yielding could be calculated from its R o value. Meanwhile, having calibrated the reactive kinetic parameters of hydrocarbon generation of vitrinite, we can calculate its hydrocarbon yielding if its paleo heat history is known. On the contrary, if when the hydrocarbon yielding is known, it is possible to deduce the heating history it experienced.Based on this basic principle, the kinetic model of hydrocarbon generation of vitrinite is constructed and calibrated, and the theoretical model of restoring paleo heat history, which can be used in sophisticated geological conditions such as in a region once undergone uplift, erosion or non linear variation of paleo teperature, is set up.Combined with measured R o values of practical samples, the paleo heat history of Haican-7 Well is recovered effectively.
The vitrinite reflectance (R o) is related to its hydrocarbon generation ratio, therefore, the hydrocarbon yielding could be calculated from its R o value. Meanwhile, having calibrated the reactive kinetic parameters of hydrocarbon generation of vitrinite, we can calculate its hydrocarbon yielding if its paleo heat history is known. On the contrary, if when the hydrocarbon yielding is known, it is possible to deduce the heating history it experienced.Based on this basic principle, the kinetic model of hydrocarbon generation of vitrinite is constructed and calibrated, and the theoretical model of restoring paleo heat history, which can be used in sophisticated geological conditions such as in a region once undergone uplift, erosion or non linear variation of paleo teperature, is set up.Combined with measured R o values of practical samples, the paleo heat history of Haican-7 Well is recovered effectively.
1996, 14(4): 45-49.
Abstract:
The oceans are proved to be a source for atomospheric methane, while in different sea area, the concentration of methane dissolved in seawater and the methane flux injected ints the atmosphere from the ocean surface vary greatly. In this study, the concentration and carbon isotopic composition of methane dissolved in the upper seawater of west Pacific Ocean were analysed, the methone evasion flux in this area was computed, additionally, the source of marine methane was also disscassed according to its carbon isotopic characteristics. The reslts of this study show that marine dissolved in the upper seawater in this region is extremly over saturated, while there are great disparities among the sorface methane concentrations in different locations, the values of which vary from 13 nmol/L to 169mol/L, methane concentration of the surface water are higher in the open sea zone than in the near shore zone, which is different from the formerly studied area; mathane dissolved in the deeper part of the uppor water (200 to 300 m), is more than that dissolved in the shallower part (0 to 100 m). Carbon isotopic composition pattern of methane, ethane and propane proves the biogenic formation of these light hydrocarbons dissolved in the upper sea water. Flux of methane across the seawater-atmosphere interface varies between 0.7 and 10.4 nmol －１m in the studied area, which is considerably high compared with the values of other open seas, while our results still proved that oceans are not animportant source for methane.
The oceans are proved to be a source for atomospheric methane, while in different sea area, the concentration of methane dissolved in seawater and the methane flux injected ints the atmosphere from the ocean surface vary greatly. In this study, the concentration and carbon isotopic composition of methane dissolved in the upper seawater of west Pacific Ocean were analysed, the methone evasion flux in this area was computed, additionally, the source of marine methane was also disscassed according to its carbon isotopic characteristics. The reslts of this study show that marine dissolved in the upper seawater in this region is extremly over saturated, while there are great disparities among the sorface methane concentrations in different locations, the values of which vary from 13 nmol/L to 169mol/L, methane concentration of the surface water are higher in the open sea zone than in the near shore zone, which is different from the formerly studied area; mathane dissolved in the deeper part of the uppor water (200 to 300 m), is more than that dissolved in the shallower part (0 to 100 m). Carbon isotopic composition pattern of methane, ethane and propane proves the biogenic formation of these light hydrocarbons dissolved in the upper sea water. Flux of methane across the seawater-atmosphere interface varies between 0.7 and 10.4 nmol －１m in the studied area, which is considerably high compared with the values of other open seas, while our results still proved that oceans are not animportant source for methane.
1996, 14(4): 61-69.
Abstract:
genera and 43 species of reef-building calcareous algae (belonging to 9 fossil communites) have been discovered in Late Tertiary organic reefs from the Chen-1 hole core of Xisha Islands. They are considered as three example organic reef sections together with 7 genera and 16 species of reef-building calcareous algae (belonging to 7 fossil communities, Chen Shizhong, 1987) discovered in the Huizhou 33 1 1 hole of the pearl river mouth basin and 8 genera and 21 species (belonging to 5 fossil communities, Zhengdingqian, 1981) in the Ying-6 hole of the Yingge Sea-Qiongdongnan Basin in the study area so far. Detailed discussion is presented in this paper on the forming machanic characteristics of the three organic reefs on the basis of comparative sedimentology. The most important identification mark of organic reefs is its typeical skeleton structure. On the basis of the data of identification results, distribution characters, assemblage relation and section evolution regularity concerning the fossil communities of the three organic reefs, the paper proposed that Melobesiae, Corallinae and Halimeda played a part of "pathbreaker", "main force" and "taking in team" in the reef-building process, espeically Halimeda (Chlorophyta), which is one of the most important skeleton organisms to form the section in Xisha organic reefs and is of great paleao oceanographic significance in exploring Chinese "Messinian" events (the Mediterranean salinity crisis)-" South China Sea" events. It is suggested in the paper that epicontinental sea is different from shelf sea in sedimentary environment in the Xisha Islands and northern South China Sea. The reef-building bases are carbonate platform, Pre-Tertiary basement rocks or old platfrom. The main reef-building phase occurred at different stages of Miocene and important rock types are represented by Corallinaceae reef dolomite rocks, Halimeda reef dolomite rocks and Corallinaceae reef carbonate rocks. The reservoir property of organic reefs in the three areas was controlled by the transgression and dolomilization. The Huizhou 33 1 1 hole recorded several transgression processes. In the Xishen 1 hole, organic reefs had two dolomitization mechanisms: 1) the adjustment dolomitization; 2) seepage refluxation dolomilization. The reservoir property of organic reefs was strengthened by dolomitization effect. At least 3 types and 12 kinds of pores and over 5 kinds of pore combinations have been found and they have made up different reservoir grades. In fact, this paper pointed out that the organic reef formation took plants as dominant sources nor animals. The establishment of the three algae reef sections is the best judgement. The above-mentioned understandings, especially the systematic testing data on rock physical properties are expected to be applied as reference to oil and gas explorations in organic reefs in the Wanan-Zengmu basin in the south part of the South China Sea.
genera and 43 species of reef-building calcareous algae (belonging to 9 fossil communites) have been discovered in Late Tertiary organic reefs from the Chen-1 hole core of Xisha Islands. They are considered as three example organic reef sections together with 7 genera and 16 species of reef-building calcareous algae (belonging to 7 fossil communities, Chen Shizhong, 1987) discovered in the Huizhou 33 1 1 hole of the pearl river mouth basin and 8 genera and 21 species (belonging to 5 fossil communities, Zhengdingqian, 1981) in the Ying-6 hole of the Yingge Sea-Qiongdongnan Basin in the study area so far. Detailed discussion is presented in this paper on the forming machanic characteristics of the three organic reefs on the basis of comparative sedimentology. The most important identification mark of organic reefs is its typeical skeleton structure. On the basis of the data of identification results, distribution characters, assemblage relation and section evolution regularity concerning the fossil communities of the three organic reefs, the paper proposed that Melobesiae, Corallinae and Halimeda played a part of "pathbreaker", "main force" and "taking in team" in the reef-building process, espeically Halimeda (Chlorophyta), which is one of the most important skeleton organisms to form the section in Xisha organic reefs and is of great paleao oceanographic significance in exploring Chinese "Messinian" events (the Mediterranean salinity crisis)-" South China Sea" events. It is suggested in the paper that epicontinental sea is different from shelf sea in sedimentary environment in the Xisha Islands and northern South China Sea. The reef-building bases are carbonate platform, Pre-Tertiary basement rocks or old platfrom. The main reef-building phase occurred at different stages of Miocene and important rock types are represented by Corallinaceae reef dolomite rocks, Halimeda reef dolomite rocks and Corallinaceae reef carbonate rocks. The reservoir property of organic reefs in the three areas was controlled by the transgression and dolomilization. The Huizhou 33 1 1 hole recorded several transgression processes. In the Xishen 1 hole, organic reefs had two dolomitization mechanisms: 1) the adjustment dolomitization; 2) seepage refluxation dolomilization. The reservoir property of organic reefs was strengthened by dolomitization effect. At least 3 types and 12 kinds of pores and over 5 kinds of pore combinations have been found and they have made up different reservoir grades. In fact, this paper pointed out that the organic reef formation took plants as dominant sources nor animals. The establishment of the three algae reef sections is the best judgement. The above-mentioned understandings, especially the systematic testing data on rock physical properties are expected to be applied as reference to oil and gas explorations in organic reefs in the Wanan-Zengmu basin in the south part of the South China Sea.
1996, 14(4): 77-83.
Abstract:
The migration and accumulation of hydrocarbons can be divided into three stages (1) the mature crude oil of the Indo-China movement stage; (2) high-mature to condensate oil of the Yanshan movement to the Himalayan movement stage; (3) pyrolysis of liquid hydrocarbons and methane gas of Himalayan movement stage by studies on the types, attitude and distribution in the cement and filling of the Carboniferous reservoir bed. According to the character of the composition of hydrocarbon inclusions and distribution of the reservoir bitumen, the studied area has three regional zones with different history of migration, accumulation and maturity, which are the Kaijiang-Zhongxian-Chongqin region, Daxian-Guangan region and Wanxian-Yunyiang region.
The migration and accumulation of hydrocarbons can be divided into three stages (1) the mature crude oil of the Indo-China movement stage; (2) high-mature to condensate oil of the Yanshan movement to the Himalayan movement stage; (3) pyrolysis of liquid hydrocarbons and methane gas of Himalayan movement stage by studies on the types, attitude and distribution in the cement and filling of the Carboniferous reservoir bed. According to the character of the composition of hydrocarbon inclusions and distribution of the reservoir bitumen, the studied area has three regional zones with different history of migration, accumulation and maturity, which are the Kaijiang-Zhongxian-Chongqin region, Daxian-Guangan region and Wanxian-Yunyiang region.
1996, 14(4): 94-101.
Abstract:
This paper deals with dynamicly the histrory of oil-gas migration and accumulation, especially in Banqiao Depression. In this paper we developed and discussed the processing methods of faults in the ancient fluid potential simulation, graded benefitial exploration areas, and pointed out that self-generated and self-reservoired oil and gas were usually located in high potential areas. Furthermore, It's illustrated that the younger basin, similar to Banqiao Depression, is the characteristic of sedimentry pressure centrafugal fluid, and the water moving direction is the same with that of fluid potential. At last, the authos predicted that there are series of hopeful areas distributed in Banqiao Depression.
This paper deals with dynamicly the histrory of oil-gas migration and accumulation, especially in Banqiao Depression. In this paper we developed and discussed the processing methods of faults in the ancient fluid potential simulation, graded benefitial exploration areas, and pointed out that self-generated and self-reservoired oil and gas were usually located in high potential areas. Furthermore, It's illustrated that the younger basin, similar to Banqiao Depression, is the characteristic of sedimentry pressure centrafugal fluid, and the water moving direction is the same with that of fluid potential. At last, the authos predicted that there are series of hopeful areas distributed in Banqiao Depression.
1996, 14(4): 108-113.
Abstract:
Recently, studies on the pore-texture have made significant progress. Many researchers consider that the pore-texture is a fractional texture with the self-similarity in sandstone. In this study, the authors inferred the power relationship between Φ(r) and r with fractional geometric principles, i.e. Φ(r)=K·r 3-0 (1) Where Φ(r)-porosity whose pore radius is less than r, r-pore radius, k-proportional constant, and D-fractional dimension of the pore-texture. The relationship between Φ(r) and r obtained from the mercury injection curve usually follows a straight line in the log-log plot. Thus, it was proved that the power relationship between Φ(r) and r inferred theoretically is correct and could dprovide a method for measuring fractional dimension of the pore-texture. The experimental results showed that fractional dimension of the pore-texture is a fraction between 2 and 3 in the three dimensions and that its size indicates a complex degree of the pore-texture which has a close relationship with the reservoir property in sandstones. Surface shape and size distribution of pores are either relatively simple if D is close to 2, so the reservoir property is extremely good; or relatively complex if D close to 3, so the reservoir property extremely poor in sandstones. Comparing Eq.(1) with Φ(r)'s expression which is transformed from Milligan and Adams' formula of the accumulational pore volume, the authers considered that types of the pore-texture with different origin have different fractional dimensions, and fractional dimensions of the pore-texture with either the same or similar origin are usually within a certain range. It is seen that fractional dmension not only discribes mathmatical characters of complex degree of the pore-texture, but also indicates its original characters. In this paper, this is theoretical basis to classify and evaluate the pore-texture in sandstones. In the study on the Xia Ermen oilfield, although the fractional dimension value of the pore-texture has a closer relatinship with permeability, no clear relationship exists with porosity in sandstones. The pore-textures could be divided into four types clearly according to distribution characters of samples on the fractional dimension's axis. Among these, the reservoir property of type Ⅰ is good, type Ⅱ moderate, type Ⅲ poor and type Ⅳ worst. The results are consistent with those observed with microscope and scanning electric microscope, showing that fractional dimension is of importance in classification and evaluation of the pore-texture in sandstones.
Recently, studies on the pore-texture have made significant progress. Many researchers consider that the pore-texture is a fractional texture with the self-similarity in sandstone. In this study, the authors inferred the power relationship between Φ(r) and r with fractional geometric principles, i.e. Φ(r)=K·r 3-0 (1) Where Φ(r)-porosity whose pore radius is less than r, r-pore radius, k-proportional constant, and D-fractional dimension of the pore-texture. The relationship between Φ(r) and r obtained from the mercury injection curve usually follows a straight line in the log-log plot. Thus, it was proved that the power relationship between Φ(r) and r inferred theoretically is correct and could dprovide a method for measuring fractional dimension of the pore-texture. The experimental results showed that fractional dimension of the pore-texture is a fraction between 2 and 3 in the three dimensions and that its size indicates a complex degree of the pore-texture which has a close relationship with the reservoir property in sandstones. Surface shape and size distribution of pores are either relatively simple if D is close to 2, so the reservoir property is extremely good; or relatively complex if D close to 3, so the reservoir property extremely poor in sandstones. Comparing Eq.(1) with Φ(r)'s expression which is transformed from Milligan and Adams' formula of the accumulational pore volume, the authers considered that types of the pore-texture with different origin have different fractional dimensions, and fractional dimensions of the pore-texture with either the same or similar origin are usually within a certain range. It is seen that fractional dmension not only discribes mathmatical characters of complex degree of the pore-texture, but also indicates its original characters. In this paper, this is theoretical basis to classify and evaluate the pore-texture in sandstones. In the study on the Xia Ermen oilfield, although the fractional dimension value of the pore-texture has a closer relatinship with permeability, no clear relationship exists with porosity in sandstones. The pore-textures could be divided into four types clearly according to distribution characters of samples on the fractional dimension's axis. Among these, the reservoir property of type Ⅰ is good, type Ⅱ moderate, type Ⅲ poor and type Ⅳ worst. The results are consistent with those observed with microscope and scanning electric microscope, showing that fractional dimension is of importance in classification and evaluation of the pore-texture in sandstones.
1996, 14(4): 122-128.
Abstract:
The Dashuizha phosphorus mine is located in a place where Shifang and Mianzhu of Sichuan Province meet and where the brecciated phosphorus ore is in lower part of the original "Shifang type" one. The original "Shifang type" phosphorus ore was mainly composed of the palingenetic marine phosphorite of Middle and Late Devonian Epoch including upper ore beds of goyazite (originally called sulfur goyazite ore ) and lower brecciated phosphorite. It was found by recent studies of the authors that the upper mineral bed of goyazite belongs to the marine facies phosphorite of Middle Devonian Epoch while the lower part brecciated phosphorite to the continental facies one whose geological characteristics are very similar to the Qinglongshao phosphorite ore of Yunnan Province. The phosphorus ore bed bearing goyazite and kaolinite were found to be in onlap unconfornity in the apical plate of the Qinglongshao brecciated phosphorite, which indicates the stratigraphic pattern and bed sequence of the Qinglongshao phosphorus ore are very similar to those of the Dashuizha ore. The present study has confirmed that both the brecciated phosphorite systems are continental facies and that the Meishucun phosphorite of the Lower Cambrian was weathered, accumulated, consolidated and so on for a long time from the Late Cambrian to Late Devonian. Thus, the Qinglongshao and Dashuizha phosphorus ores could be called the "Dashuizha type" phosphorus ore.
The Dashuizha phosphorus mine is located in a place where Shifang and Mianzhu of Sichuan Province meet and where the brecciated phosphorus ore is in lower part of the original "Shifang type" one. The original "Shifang type" phosphorus ore was mainly composed of the palingenetic marine phosphorite of Middle and Late Devonian Epoch including upper ore beds of goyazite (originally called sulfur goyazite ore ) and lower brecciated phosphorite. It was found by recent studies of the authors that the upper mineral bed of goyazite belongs to the marine facies phosphorite of Middle Devonian Epoch while the lower part brecciated phosphorite to the continental facies one whose geological characteristics are very similar to the Qinglongshao phosphorite ore of Yunnan Province. The phosphorus ore bed bearing goyazite and kaolinite were found to be in onlap unconfornity in the apical plate of the Qinglongshao brecciated phosphorite, which indicates the stratigraphic pattern and bed sequence of the Qinglongshao phosphorus ore are very similar to those of the Dashuizha ore. The present study has confirmed that both the brecciated phosphorite systems are continental facies and that the Meishucun phosphorite of the Lower Cambrian was weathered, accumulated, consolidated and so on for a long time from the Late Cambrian to Late Devonian. Thus, the Qinglongshao and Dashuizha phosphorus ores could be called the "Dashuizha type" phosphorus ore.
1996, 14(4): 134-140.
Abstract:
The continental Jurassic system in Northwest China can be classed into 10 stratigraphic districts and 7 subdistricts based on a systematic study of large quantity of continental Jurassic geologic sections in Northwest China, such as that paleotectonic frameworks, basement characters, tectonic deformation, magmatic activity, sedimentary formation, paleao-biota attributes, stratigraphic development and contact relations. In terms of the stratigrsphic province, the paper deats with Jurassic lithofacies and Plaeogeography, and the distributive regularity of sedimentary minerals such as petroleum and coal resources is discussed as well.
The continental Jurassic system in Northwest China can be classed into 10 stratigraphic districts and 7 subdistricts based on a systematic study of large quantity of continental Jurassic geologic sections in Northwest China, such as that paleotectonic frameworks, basement characters, tectonic deformation, magmatic activity, sedimentary formation, paleao-biota attributes, stratigraphic development and contact relations. In terms of the stratigrsphic province, the paper deats with Jurassic lithofacies and Plaeogeography, and the distributive regularity of sedimentary minerals such as petroleum and coal resources is discussed as well.
1996, 14(4): 148-153.
Abstract:
This paper discusses the relation of sedimentation between the loess, red clay and deposits of the Sanmen lake in the Chinese loess highland by studies of magnetostratigraph, biostratigraph, sedimentology and environmental analysis. Main results are 1)the Early Pleistocene loess overlies continuously on the top of the Neogene red clay in some sections. 2)the Brunhes normal polarity zone and Matsuyama reversal polarity zone were recorded in the loess section and the deposit of the Sanmen lake. The B/M boundary is located in the L 8 loess layer. The J subzone is located between the S 10S 13loess beds. The O subzone is located in S 22 S 23 loess beds, or in the deposit of the Sanmen lake. The M/Ga boundary corresponds to the loess/red clay boundary, and also basically to the Sanmen group/Youhe group boundary. 3)the red clay includes not only the sediment of Miocene Baode epoch, but also the deposits of Pliocene and Miocene. The Pliocene Jingle group recorded the Gauss normal polarity zone and the Gilbert reversel polarity zone, but the Miocene Lantian group recorded Epoch 5. 4)the deposit of the Sanmen lake includes the Early Pleistocene Sanmen group (1.20-2.45Ma, Matsuyama reversel polarity zone) and the Late Pliocene Youhe group (2.50-3.50Ma, Gauss mormal polarity zone). The Sanmen group and Wuyu loess are the contemporaneous different facies deposits, the Matsuyama reversal polarity zone was recorded in them. The Youhe group and the upper red clay(upper of Jingle) are the contemporaneous different facies deposits as well, which recorded the Gauss normal polarity zone.
This paper discusses the relation of sedimentation between the loess, red clay and deposits of the Sanmen lake in the Chinese loess highland by studies of magnetostratigraph, biostratigraph, sedimentology and environmental analysis. Main results are 1)the Early Pleistocene loess overlies continuously on the top of the Neogene red clay in some sections. 2)the Brunhes normal polarity zone and Matsuyama reversal polarity zone were recorded in the loess section and the deposit of the Sanmen lake. The B/M boundary is located in the L 8 loess layer. The J subzone is located between the S 10S 13loess beds. The O subzone is located in S 22 S 23 loess beds, or in the deposit of the Sanmen lake. The M/Ga boundary corresponds to the loess/red clay boundary, and also basically to the Sanmen group/Youhe group boundary. 3)the red clay includes not only the sediment of Miocene Baode epoch, but also the deposits of Pliocene and Miocene. The Pliocene Jingle group recorded the Gauss normal polarity zone and the Gilbert reversel polarity zone, but the Miocene Lantian group recorded Epoch 5. 4)the deposit of the Sanmen lake includes the Early Pleistocene Sanmen group (1.20-2.45Ma, Matsuyama reversel polarity zone) and the Late Pliocene Youhe group (2.50-3.50Ma, Gauss mormal polarity zone). The Sanmen group and Wuyu loess are the contemporaneous different facies deposits, the Matsuyama reversal polarity zone was recorded in them. The Youhe group and the upper red clay(upper of Jingle) are the contemporaneous different facies deposits as well, which recorded the Gauss normal polarity zone.
1996, 14(4): 161-167.
Abstract:
The distributive regulation of sulfur in coal is discussed on the basis of sedimentology, coal forming environment, geochemistry, etc. in this study. And the relationship between the coal forming environment and sulfur in coal is clarified in detail. The study indicates that the occurrence information of sulfur in coal is not only influenced by coal accumuating environment, but also by roof depositional environment. The coal forming environment has laid a foundation of sulfur occurrence in coal, while roof depositional environment is important and key link to make coal with high sulfur. The roof depositional environment of brackish muddy water tidal flat leads to high pyritized sulfur in underlying coal while that of clean marine water tidal flat leads to high organic sulfur in underlying coal.
The distributive regulation of sulfur in coal is discussed on the basis of sedimentology, coal forming environment, geochemistry, etc. in this study. And the relationship between the coal forming environment and sulfur in coal is clarified in detail. The study indicates that the occurrence information of sulfur in coal is not only influenced by coal accumuating environment, but also by roof depositional environment. The coal forming environment has laid a foundation of sulfur occurrence in coal, while roof depositional environment is important and key link to make coal with high sulfur. The roof depositional environment of brackish muddy water tidal flat leads to high pyritized sulfur in underlying coal while that of clean marine water tidal flat leads to high organic sulfur in underlying coal.
1996, 14(4): 15-23.
Abstract:
In this paper, a practical approach is presented to classify the hydrocarbon and hydrocarbon bearing inclusions based on recent studies published by others as well as the authors' own research experience in this field. The properties of fluid phases, compositions and homogenization temperatures of various types of hydrocarbon and hydrocarbon bearing inclusions have been described and studied in details. In a reservoir, the higher the homogenization temperatures of the oil inclusions, the higher the contents of gas and volatile short chain compounds. Based on the variation of homogenization temperatures and the relationship of homogenization temperatures between oil inclusions and associated aqueous inclusions, the variation of contents of gas and volatile short chain compounds in a reservoir could be elucidated.Furthermore, the efficiency and limitation of the method to determine the entrapment temperatures and pressures of fluid inclusions based on PVT diagrams of oil inclusions and associated aqueous inclusions are evaluated. Finally, some possible models have been presented to interpret the entrapments of various types of hydrocarbon and hydrocarbon bearing inclusions and their implications to petroleum geology and geochemistry are discussed as well.
In this paper, a practical approach is presented to classify the hydrocarbon and hydrocarbon bearing inclusions based on recent studies published by others as well as the authors' own research experience in this field. The properties of fluid phases, compositions and homogenization temperatures of various types of hydrocarbon and hydrocarbon bearing inclusions have been described and studied in details. In a reservoir, the higher the homogenization temperatures of the oil inclusions, the higher the contents of gas and volatile short chain compounds. Based on the variation of homogenization temperatures and the relationship of homogenization temperatures between oil inclusions and associated aqueous inclusions, the variation of contents of gas and volatile short chain compounds in a reservoir could be elucidated.Furthermore, the efficiency and limitation of the method to determine the entrapment temperatures and pressures of fluid inclusions based on PVT diagrams of oil inclusions and associated aqueous inclusions are evaluated. Finally, some possible models have been presented to interpret the entrapments of various types of hydrocarbon and hydrocarbon bearing inclusions and their implications to petroleum geology and geochemistry are discussed as well.
1996, 14(4): 31-37.
Abstract:
A kind of modern fungi Alternaria tenuis were selected for a thermal simulation experiment, which is smiliar to Multicellaesporites (common in stratum). Being divided into seven groups by simulating temperatures, (normal temperature, 100℃, 200℃, 250℃, 300℃, 400℃, 500℃) these samples were conducted in a lot of experiments, such as Gas Analysis, Elements Analysis, Ultimate Analysis, Thermal Simulation Chromatogram Analysis, Infrared Spectrum Analysis, Organic High Differential Thermal Analysis and so on. Results showed that fungi, corresponding to the type Ⅰ Ⅱ kerogen, is a good source for generating hydrocarbons and 300℃ 400℃ is the summit of generating oil(gas).The fungi thermal simulation examination has distinctly revealed the course of thermal evolution of organic matter and oil/gas generation.
A kind of modern fungi Alternaria tenuis were selected for a thermal simulation experiment, which is smiliar to Multicellaesporites (common in stratum). Being divided into seven groups by simulating temperatures, (normal temperature, 100℃, 200℃, 250℃, 300℃, 400℃, 500℃) these samples were conducted in a lot of experiments, such as Gas Analysis, Elements Analysis, Ultimate Analysis, Thermal Simulation Chromatogram Analysis, Infrared Spectrum Analysis, Organic High Differential Thermal Analysis and so on. Results showed that fungi, corresponding to the type Ⅰ Ⅱ kerogen, is a good source for generating hydrocarbons and 300℃ 400℃ is the summit of generating oil(gas).The fungi thermal simulation examination has distinctly revealed the course of thermal evolution of organic matter and oil/gas generation.
1996, 14(4): 50-60.
Abstract:
The main foundations of using the basic concepts of sequence stratigraphy in Songliao Basin and the fundamental characteristics of nonmarine seqences in Cretaceous are dealt with in the present paper. Around the sequence boundaries some erosional or exposure evidences in cores were found such as palaeosol or rootlet bed, fluvial lag conglomerate, transgressive lag conglowerate, subaqueous slumping, caliche nodules as well as geological record of the facies that changed abruptly, and there were tempestite, alluvial fan, deltatic front sheet flow deposit, oolitic limestone, bioclastic limestone, sandstone with excellent porosity and penetrability and volcanics upon the sequence boundaries. The logging responses of sequence boundaries were characteristic of progradation to retrogradation gradually, aggradation to retrogradation abruptly, progradation to aggradation or progradation to progradation and so on. It could be seen that on the seismic sections there were some reflecting configurations of truncation, onlap and downlap near the sequence boundaries. On the basis of the comprehensive interpretations of cores, well logs and seismic lines, the paper principally demonstrated the features of depositional system tracts of the major oil payzones. Based on these studies mentioned above, the authors constructed the idearlized models of sequence stratigraphy for the nonmarine Sonliao Basin. The lowstand system tract was composed of alluvial fan, river mouth bar, "incised valley" guests, sluming, debris flow deposit, turbidite and deltatic front flow deposits. The transgressive system tract consisted of tempesitite, sand bank and sand bar, carbonate shoal, sheet sandstone in deltatic front, stromatolite and so forth. The typical condensed section, which is located on the top of TST and on the bottom of HST, was composed of dark shales with marine nannofossils. The highstand system tract was mainly made up of delta, fan delta and meandering stream systems.
The main foundations of using the basic concepts of sequence stratigraphy in Songliao Basin and the fundamental characteristics of nonmarine seqences in Cretaceous are dealt with in the present paper. Around the sequence boundaries some erosional or exposure evidences in cores were found such as palaeosol or rootlet bed, fluvial lag conglomerate, transgressive lag conglowerate, subaqueous slumping, caliche nodules as well as geological record of the facies that changed abruptly, and there were tempestite, alluvial fan, deltatic front sheet flow deposit, oolitic limestone, bioclastic limestone, sandstone with excellent porosity and penetrability and volcanics upon the sequence boundaries. The logging responses of sequence boundaries were characteristic of progradation to retrogradation gradually, aggradation to retrogradation abruptly, progradation to aggradation or progradation to progradation and so on. It could be seen that on the seismic sections there were some reflecting configurations of truncation, onlap and downlap near the sequence boundaries. On the basis of the comprehensive interpretations of cores, well logs and seismic lines, the paper principally demonstrated the features of depositional system tracts of the major oil payzones. Based on these studies mentioned above, the authors constructed the idearlized models of sequence stratigraphy for the nonmarine Sonliao Basin. The lowstand system tract was composed of alluvial fan, river mouth bar, "incised valley" guests, sluming, debris flow deposit, turbidite and deltatic front flow deposits. The transgressive system tract consisted of tempesitite, sand bank and sand bar, carbonate shoal, sheet sandstone in deltatic front, stromatolite and so forth. The typical condensed section, which is located on the top of TST and on the bottom of HST, was composed of dark shales with marine nannofossils. The highstand system tract was mainly made up of delta, fan delta and meandering stream systems.
1996, 14(4): 70-76.
Abstract:
The bottom of the lower Youshashan Formation (Neogene) was deposited by a braided deltaic system. The No.68 sandbody was a distributary channel cut into the exposed lake bed during the lower stand stage. Sediments of the sandbody were transpoted by the longitudinal braided deltaic system located between the Qimantage and Argin mountains. The No.68 sandbody has the similar upward thinning structure and grain size sequence as most of fluvial sandbodies have. 3D sampling net work controls 158 meters long of the sandbody. The sandbody is 42.5 meters wide and 5.33 meters thick, it widens and thins toward the downstream, which is also one of the common characters of all deltaic front distributary channels. We recognized 12 lithofacies within the sandbody, they are: Gpr, Glt, Ge, Slt, Smt, Spr,Sla,Sbm, Sst, SIcr, SIh, Mr1. 6 lithoracies assemblages are composed of the 12 lithofacies, they are: Ge-Gpr-Glt; Glt-Slt; Slt-Smt; Glt-Sbm(Spr); Sst-SIt, SIcr(Gpr,Spr,Sst)-Mrl. There are 6 kinds of architectural elements in the sandbody, they are: lateral accretion(LA), longitudinal bar(LB), transverse bar(TB), simple gravel filling(GF), simple sand filling(SF), levee and sandflat(LF). LA is 8.8 14.4 m wide and has the ratio of width/thichness(W/T) 5.5 7.2, LB is 10 12.4 m wide and its W/T is 4.17 5.17, TB is 6.4 m wide and its W/T is 2.67, GF is 30 m wide and its W/T is 40, SF is 12 24 m wide and W/T is 15 30, LF is 1.76 m thick. LA,LB and TB are situated at the lower part of the sandbody, GF and SF develop at the upper part of the sandbody, LF occurs at the two channel banks. A 7 order surface hierarchy in the sandbody has been found in accordance with the sedimentary events. First order is the top and bottom surface of the sandbody, second order is sedimentary phase surface, third order is the surface of sub-phase, fourth order shows the surface of died channel bars, fifth order surface is the accretion surface within bars, sixth order represents the cross bedding set surface and the seventh order is the surface of laminar. By the surface hierarchy, the depositional process of the sandbody was reconstructed by 3 sedimentary phases and 6 sub-phases. Compared the architectural element reservoir model with the thin grid proto-type reservoir model, it could be concluded that the two models are very similar in permeability distribution. This tells us that we can build the predictable reservoir model using the method of architectural element analysis, with the predictable model we can predict remaining oil distribution and provide more useful information for EOR.
The bottom of the lower Youshashan Formation (Neogene) was deposited by a braided deltaic system. The No.68 sandbody was a distributary channel cut into the exposed lake bed during the lower stand stage. Sediments of the sandbody were transpoted by the longitudinal braided deltaic system located between the Qimantage and Argin mountains. The No.68 sandbody has the similar upward thinning structure and grain size sequence as most of fluvial sandbodies have. 3D sampling net work controls 158 meters long of the sandbody. The sandbody is 42.5 meters wide and 5.33 meters thick, it widens and thins toward the downstream, which is also one of the common characters of all deltaic front distributary channels. We recognized 12 lithofacies within the sandbody, they are: Gpr, Glt, Ge, Slt, Smt, Spr,Sla,Sbm, Sst, SIcr, SIh, Mr1. 6 lithoracies assemblages are composed of the 12 lithofacies, they are: Ge-Gpr-Glt; Glt-Slt; Slt-Smt; Glt-Sbm(Spr); Sst-SIt, SIcr(Gpr,Spr,Sst)-Mrl. There are 6 kinds of architectural elements in the sandbody, they are: lateral accretion(LA), longitudinal bar(LB), transverse bar(TB), simple gravel filling(GF), simple sand filling(SF), levee and sandflat(LF). LA is 8.8 14.4 m wide and has the ratio of width/thichness(W/T) 5.5 7.2, LB is 10 12.4 m wide and its W/T is 4.17 5.17, TB is 6.4 m wide and its W/T is 2.67, GF is 30 m wide and its W/T is 40, SF is 12 24 m wide and W/T is 15 30, LF is 1.76 m thick. LA,LB and TB are situated at the lower part of the sandbody, GF and SF develop at the upper part of the sandbody, LF occurs at the two channel banks. A 7 order surface hierarchy in the sandbody has been found in accordance with the sedimentary events. First order is the top and bottom surface of the sandbody, second order is sedimentary phase surface, third order is the surface of sub-phase, fourth order shows the surface of died channel bars, fifth order surface is the accretion surface within bars, sixth order represents the cross bedding set surface and the seventh order is the surface of laminar. By the surface hierarchy, the depositional process of the sandbody was reconstructed by 3 sedimentary phases and 6 sub-phases. Compared the architectural element reservoir model with the thin grid proto-type reservoir model, it could be concluded that the two models are very similar in permeability distribution. This tells us that we can build the predictable reservoir model using the method of architectural element analysis, with the predictable model we can predict remaining oil distribution and provide more useful information for EOR.
1996, 14(4): 84-93.
Abstract:
The Paleogeographic pattern, regional sea level changes and reef distribution development were obviously controlled by different kinds of tectonic units. According to the tectonic unit characteristics of Upper Yangtze Platform such as the basement features and different kinds of platform margins, the authors discuss the platform topography, platform margins topography and other inter platform units and their controling activity to Silurian sedimentary environments and the reef development evolution. At the north margin of Upper Ynagtze Platform (South Qinling tectonic zone), which is a passive continental margin, the sedimentary environment was suitable for the development of reefs and the different kinds of reefs grew there. The west margin of the Platform (Jin Shajiang tectonic zone) belonged to an active continental margin, some patch reefs and biostromes grew on the island arc area. In the Platform, some areas were influenced by uplifts (NW Sichuan, SE Sichuan and N Guizhou) and the ramp sedimentary environments were formed. Usually, in the shallow ramp environment, the reefs developed very well with high deversity. But along the inter platform deep fracture zone (Longmenshan, Erlangshan Panxi Rift), reefs did not develop, only biostrome and small-patch reef assemblage can be seen. During the Silurian, the Upper Yangtze Platform was influenced obviously by global sea level change. Because of the sea level down, most part of Yangtze Platform did not receive deposits after Wenlock. But the platform margin depression areas were not influenced by the global sea level change, and reefs still developed after Wenlock. It indicates that the regional tectonic movement also controls the sea level change.
The Paleogeographic pattern, regional sea level changes and reef distribution development were obviously controlled by different kinds of tectonic units. According to the tectonic unit characteristics of Upper Yangtze Platform such as the basement features and different kinds of platform margins, the authors discuss the platform topography, platform margins topography and other inter platform units and their controling activity to Silurian sedimentary environments and the reef development evolution. At the north margin of Upper Ynagtze Platform (South Qinling tectonic zone), which is a passive continental margin, the sedimentary environment was suitable for the development of reefs and the different kinds of reefs grew there. The west margin of the Platform (Jin Shajiang tectonic zone) belonged to an active continental margin, some patch reefs and biostromes grew on the island arc area. In the Platform, some areas were influenced by uplifts (NW Sichuan, SE Sichuan and N Guizhou) and the ramp sedimentary environments were formed. Usually, in the shallow ramp environment, the reefs developed very well with high deversity. But along the inter platform deep fracture zone (Longmenshan, Erlangshan Panxi Rift), reefs did not develop, only biostrome and small-patch reef assemblage can be seen. During the Silurian, the Upper Yangtze Platform was influenced obviously by global sea level change. Because of the sea level down, most part of Yangtze Platform did not receive deposits after Wenlock. But the platform margin depression areas were not influenced by the global sea level change, and reefs still developed after Wenlock. It indicates that the regional tectonic movement also controls the sea level change.
1996, 14(4): 102-107.
Abstract:
The Eastern depression is one of the three depressions of Liaohe Rift and located in the lower Liaohe plain in Liaoning Province. This paper indicates by means of the analysis of caprock types, effect of compaction on seal ability of caprocks and the seal ability of volcanic caprocks that local caprocks are very developed, of which the best caprock is the volcanic rock, although the depression lacks the regional caprock. The variation of shale caprocks in different beds is great. The mudstone caprock was formed in the periods of saltatory and tight compactions in the middle-deep horizons, but the volcanic caprock complemented the lack of mudstone caprock in shallow horizons. Based on the relationship between mudstone caprock and reservoir, it is known that there is a poor caprock but good reservoir in shallow horizons, but it is contrary in deep horizons. In view of mudstone caprock, the medium-large gas reservoirs should be formed in middle-deep horizons, and small gas reservoirs should be formed in shallow horizons. However, in the depression well-developed volcanic caprocks increased the probability of formation of large gas reservoirs in shallow horizons, which broke the regularity of vertical distribution of natural gas on the condition of mudstone caprock. According to the distribution of breakthrough pressure of mudstone caprock in different horizons and depths as well as the distribution of volcanic rocks, the exploration potential of gas reservoirs in deep horizons was proposed.
The Eastern depression is one of the three depressions of Liaohe Rift and located in the lower Liaohe plain in Liaoning Province. This paper indicates by means of the analysis of caprock types, effect of compaction on seal ability of caprocks and the seal ability of volcanic caprocks that local caprocks are very developed, of which the best caprock is the volcanic rock, although the depression lacks the regional caprock. The variation of shale caprocks in different beds is great. The mudstone caprock was formed in the periods of saltatory and tight compactions in the middle-deep horizons, but the volcanic caprock complemented the lack of mudstone caprock in shallow horizons. Based on the relationship between mudstone caprock and reservoir, it is known that there is a poor caprock but good reservoir in shallow horizons, but it is contrary in deep horizons. In view of mudstone caprock, the medium-large gas reservoirs should be formed in middle-deep horizons, and small gas reservoirs should be formed in shallow horizons. However, in the depression well-developed volcanic caprocks increased the probability of formation of large gas reservoirs in shallow horizons, which broke the regularity of vertical distribution of natural gas on the condition of mudstone caprock. According to the distribution of breakthrough pressure of mudstone caprock in different horizons and depths as well as the distribution of volcanic rocks, the exploration potential of gas reservoirs in deep horizons was proposed.
1996, 14(4): 114-121.
Abstract:
The sea area around the Liaohe estuary refers to a region between the Liaohe estuary to the east and the Xiaolinghe estuary to the west, of which the water depth is defined less than 20 m. Drainages which enter into the sea are the Liaohe, Shuangtaihe, Dalinghe and Xiaolinghe rivers, characterized by 9.14×10 9 m 3/a of total water discharge and 4.9×10 7 t/a sediment input. Broad tidal flat and submerged deltas were attributed to the large capicity of sedimentary input. Based on the spot investigating data(1988), the authors calculated the distribution of the suspended deposit in the northern Liaodong Bay, and analysed sediment divisions of the Liaohe delta. The results indicated that the suspended matter moved in longitudinal direction. Water and sand from the Shuangtai river and the west area of the river are the main facter for the shoal development in the eastern part of this area. During spring tide, the suspended sediment of the rivers and marine sources can remain in river mouths and aroun shallow water. Main dispersion directions of sediments are southeastwards to the western and the central areas and northeastwards to the eastern part during flood tide. During neap tide, however, sediments from rivers and resuspended sediment from the estuary migrate in the same directions mentioned-above. The investigating area is divided into six modern sediment areas, they are tide flat deposit area, subaqueous delta fine sedimentary area, estuarine sand bank deposit area, estuarine alluvial deposit area, tidal stream and wave cut deposit area, and tide and waterway deposit area. It is noted that bottom configurations of the east in this area are very complicated and the bottoms are subjected to intensive disturbing and scouring, which induce active slide and flows in underconsolidated sediments on the Liaohe delta.
The sea area around the Liaohe estuary refers to a region between the Liaohe estuary to the east and the Xiaolinghe estuary to the west, of which the water depth is defined less than 20 m. Drainages which enter into the sea are the Liaohe, Shuangtaihe, Dalinghe and Xiaolinghe rivers, characterized by 9.14×10 9 m 3/a of total water discharge and 4.9×10 7 t/a sediment input. Broad tidal flat and submerged deltas were attributed to the large capicity of sedimentary input. Based on the spot investigating data(1988), the authors calculated the distribution of the suspended deposit in the northern Liaodong Bay, and analysed sediment divisions of the Liaohe delta. The results indicated that the suspended matter moved in longitudinal direction. Water and sand from the Shuangtai river and the west area of the river are the main facter for the shoal development in the eastern part of this area. During spring tide, the suspended sediment of the rivers and marine sources can remain in river mouths and aroun shallow water. Main dispersion directions of sediments are southeastwards to the western and the central areas and northeastwards to the eastern part during flood tide. During neap tide, however, sediments from rivers and resuspended sediment from the estuary migrate in the same directions mentioned-above. The investigating area is divided into six modern sediment areas, they are tide flat deposit area, subaqueous delta fine sedimentary area, estuarine sand bank deposit area, estuarine alluvial deposit area, tidal stream and wave cut deposit area, and tide and waterway deposit area. It is noted that bottom configurations of the east in this area are very complicated and the bottoms are subjected to intensive disturbing and scouring, which induce active slide and flows in underconsolidated sediments on the Liaohe delta.
1996, 14(4): 129-133.
Abstract:
Stiff muds of the Late Pleistocene, revealed by 87 coriegs and tested by many sample analyses, are widely distributed in the entire former northern Nile delta plain. It is found on the basis of stratigraphic, lithologic, and petrologic analyses that there existed totally 14 lithosomes of stiff muds in the study area and four subfacies which are defined: Ⅰ)calcareous nodule bearing stiff muds, occurring constantly in the more outer of the all lithosomes, Ⅱ) gypsum nodule bearing stiff muds, emerging around the central sector of the almost all lithosomes, Ⅲ) shell bearing stiff muds, also distributed in central sector of the lithosomes and Ⅳ) plant debris bearing stiff muds, appearing less often. The distribution of subfacies of the stiff muds is closely related to alluvial processes. The characteristics of sediment components of stiff muds, such as calcareous nodule, gypsum nodule, jarosite, mollusk and Foraminifera, strongly demonstrate that the muds are of evaporate property within seasonally flooded alluvial sedimentary basins. Moreover, hot and dry weathers of the last period of Late Pleistocene are thus distinctively featured by the evaporate basins of stiff muds of the Nile delta, indicating the former semi-desertified Nile plain.
Stiff muds of the Late Pleistocene, revealed by 87 coriegs and tested by many sample analyses, are widely distributed in the entire former northern Nile delta plain. It is found on the basis of stratigraphic, lithologic, and petrologic analyses that there existed totally 14 lithosomes of stiff muds in the study area and four subfacies which are defined: Ⅰ)calcareous nodule bearing stiff muds, occurring constantly in the more outer of the all lithosomes, Ⅱ) gypsum nodule bearing stiff muds, emerging around the central sector of the almost all lithosomes, Ⅲ) shell bearing stiff muds, also distributed in central sector of the lithosomes and Ⅳ) plant debris bearing stiff muds, appearing less often. The distribution of subfacies of the stiff muds is closely related to alluvial processes. The characteristics of sediment components of stiff muds, such as calcareous nodule, gypsum nodule, jarosite, mollusk and Foraminifera, strongly demonstrate that the muds are of evaporate property within seasonally flooded alluvial sedimentary basins. Moreover, hot and dry weathers of the last period of Late Pleistocene are thus distinctively featured by the evaporate basins of stiff muds of the Nile delta, indicating the former semi-desertified Nile plain.
1996, 14(4): 141-147.
Abstract:
The Sedimentary attapulgite clay deposit on the boder of Jiangsu and Anhui Provinces is an important producing area of attapulgite clay in China. Ore-bearing Series is a set of sedimentary clastic rocks of shallow lake. The sedimentary medium features are as follows: 1) Various attapulgite clays have different pH values, all of them are formed in an alkalic condition; 2) According to the features and Ceanom calculated values of variant clays, the attapulgite clays are formed in a reducing condition, and part of montmorillonite clay is formed in a weak oxido-condition; 3) On the basis of stable isotopic compositions of opal and dolomite, opal-forming temperature is 71℃ 81℃ and dolomite-forming temperature is 29℃ 74℃.These features with other geochemical characteristics infered that the forming temperature of attapulgite clays is higher than the normal sedimentary temperature; 4) MgO/Al 2O 3 Sr/Ba Rb/K ratios of variant attapulgite clays showed that the forming salinity of dolomite attapulgite clay, siliceous attapulgite clay and attapulgite clay is higher than that of montmorillonite clay. To sum up, the study indicated that under the conditions of alkalic, reducing conditions and low salinity of water medium, attapulgite clay deposits could be formed in a shallow lacustrine basin. The hydrothermal solution being related to volcanic action is of certain significance to mineralization of attapulgite clay deposits.
The Sedimentary attapulgite clay deposit on the boder of Jiangsu and Anhui Provinces is an important producing area of attapulgite clay in China. Ore-bearing Series is a set of sedimentary clastic rocks of shallow lake. The sedimentary medium features are as follows: 1) Various attapulgite clays have different pH values, all of them are formed in an alkalic condition; 2) According to the features and Ceanom calculated values of variant clays, the attapulgite clays are formed in a reducing condition, and part of montmorillonite clay is formed in a weak oxido-condition; 3) On the basis of stable isotopic compositions of opal and dolomite, opal-forming temperature is 71℃ 81℃ and dolomite-forming temperature is 29℃ 74℃.These features with other geochemical characteristics infered that the forming temperature of attapulgite clays is higher than the normal sedimentary temperature; 4) MgO/Al 2O 3 Sr/Ba Rb/K ratios of variant attapulgite clays showed that the forming salinity of dolomite attapulgite clay, siliceous attapulgite clay and attapulgite clay is higher than that of montmorillonite clay. To sum up, the study indicated that under the conditions of alkalic, reducing conditions and low salinity of water medium, attapulgite clay deposits could be formed in a shallow lacustrine basin. The hydrothermal solution being related to volcanic action is of certain significance to mineralization of attapulgite clay deposits.
1996, 14(4): 154-160.
Abstract:
Pattern recognition methods are a powerful means in studying facies quantitatively. The neural network is a new method and has many improvements such as parallel processing and plasticity imitating the human brain compared with other pattern recognition methods. Permian carbonate rocks in the central Hubei basin have been identified as carbonate platform facies after traditional facies analysis. It includes five subfacies, i.e. sub-facies of districted depression, slope B, depression, slope A and shallow out. They are different from each other in rock color, mineral components, paleobiology components, rock structures and so on. The application of pattern recognition on the basis of the BP neural network for Permian carbonate rock facies studies, particularly comparison with fuzzy pattern recognition is very successful and inspiring. The correct identification ratios of fuzzy sets and the neural network are both about 75%. And the corret identification ratio of the combination of fuzzy sets and neural networks is 100%.
Pattern recognition methods are a powerful means in studying facies quantitatively. The neural network is a new method and has many improvements such as parallel processing and plasticity imitating the human brain compared with other pattern recognition methods. Permian carbonate rocks in the central Hubei basin have been identified as carbonate platform facies after traditional facies analysis. It includes five subfacies, i.e. sub-facies of districted depression, slope B, depression, slope A and shallow out. They are different from each other in rock color, mineral components, paleobiology components, rock structures and so on. The application of pattern recognition on the basis of the BP neural network for Permian carbonate rock facies studies, particularly comparison with fuzzy pattern recognition is very successful and inspiring. The correct identification ratios of fuzzy sets and the neural network are both about 75%. And the corret identification ratio of the combination of fuzzy sets and neural networks is 100%.
1996, 14(4): 168-173.
Abstract:
The ratio of strontium to barium is a universal indicator for distinguishing depositional environments. Usually, the value of Sr/Ba more or less than 1 should be responsible for marine or continental deposit, respectively. However, the authenticity of this indicator has nowadays been suspected, even negated by most of sedimentologists and geochemists because of some contradictions or opposite explanations with geological facts. By comparison study of the ratio of (Sr/Ba)Tratio of total Sr to total Ba in bulk sediment analysis, and the ratio of (Sr/Ba)A ratio of dissolvable Sr to dissolvable Ba that were extracted in dilute hydrochloric acid from the different environment of the modern Yellow (Huanghe) river delta in this paper, it is suggested that the ratio of (Sr/Ba)T is not sensitive for environment variation while the (Sr/Ba) Ashows the sensitive diversity with different sedimentary environments and, moreover,the former results are unreliable because of the disturbance of bulk Sr Ba exiting in terrigenous minerals (for example, feldspar, biotite, ect.) over the Sr and Ba formed in sedimentation. Finally, an attempt is made to evaluate the method of distinguishing sedimentary environments in use of the ratio of strontium to barium.
The ratio of strontium to barium is a universal indicator for distinguishing depositional environments. Usually, the value of Sr/Ba more or less than 1 should be responsible for marine or continental deposit, respectively. However, the authenticity of this indicator has nowadays been suspected, even negated by most of sedimentologists and geochemists because of some contradictions or opposite explanations with geological facts. By comparison study of the ratio of (Sr/Ba)Tratio of total Sr to total Ba in bulk sediment analysis, and the ratio of (Sr/Ba)A ratio of dissolvable Sr to dissolvable Ba that were extracted in dilute hydrochloric acid from the different environment of the modern Yellow (Huanghe) river delta in this paper, it is suggested that the ratio of (Sr/Ba)T is not sensitive for environment variation while the (Sr/Ba) Ashows the sensitive diversity with different sedimentary environments and, moreover,the former results are unreliable because of the disturbance of bulk Sr Ba exiting in terrigenous minerals (for example, feldspar, biotite, ect.) over the Sr and Ba formed in sedimentation. Finally, an attempt is made to evaluate the method of distinguishing sedimentary environments in use of the ratio of strontium to barium.
