1985 Vol. 3, No. 3
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Display Method:
1985, 3(3): 1-6.
Abstract:
According to their fabric features, Sinian-Cambrian Phosphorites in South China can be classified into three major basic types: micrograined, grained and crust-grained phosphorites, among which the textural component of the crust-grained phosphorite is predominately made up of phosphate crust-grains formed by microorganism. There are six forms of phosphate microorganism found in the phosphate crust-grains; ( 1 ) tube-shaped, ( 2 ) rod-shaped, ( 3 ) fibrous, ( 4 ) microglobal, ( 5 ) clumping, ( 6 ) tricuspid. All of them not only have distinct form features of microorganism,but also remain important organic components-amino acid and nucleic-acid-of organic tissues in their fossils. It is known that phosphorus, as a basic nutrient, is so necessary for the growth of all microorganism that none of them would not depend on it. Phosphorus is a structural element of enzymes, adenosine triphosphate, ribonucleic acid, desoxyri-bonucleic acid,nucleic acid and phospholipids,from which cell membranes are made. Microorganism plays a very important role in the circle of phosphorus on the earth. It is the microorganism action that is an important link in the circle of 'phosphorus in the ocean for the concentration of phosphorus to form ore deposits. Recent year studies on liquid crystal materials hane convinced the author that consideralle physiological behaviors of phosphorus-thirsty microorganism, i. e. the preferential extraction, accumulation and transportation of phosphates, may be attributed to the liquid crystal form of the tissues and cells of phosphorus-thirsty microorganism
According to their fabric features, Sinian-Cambrian Phosphorites in South China can be classified into three major basic types: micrograined, grained and crust-grained phosphorites, among which the textural component of the crust-grained phosphorite is predominately made up of phosphate crust-grains formed by microorganism. There are six forms of phosphate microorganism found in the phosphate crust-grains; ( 1 ) tube-shaped, ( 2 ) rod-shaped, ( 3 ) fibrous, ( 4 ) microglobal, ( 5 ) clumping, ( 6 ) tricuspid. All of them not only have distinct form features of microorganism,but also remain important organic components-amino acid and nucleic-acid-of organic tissues in their fossils. It is known that phosphorus, as a basic nutrient, is so necessary for the growth of all microorganism that none of them would not depend on it. Phosphorus is a structural element of enzymes, adenosine triphosphate, ribonucleic acid, desoxyri-bonucleic acid,nucleic acid and phospholipids,from which cell membranes are made. Microorganism plays a very important role in the circle of phosphorus on the earth. It is the microorganism action that is an important link in the circle of 'phosphorus in the ocean for the concentration of phosphorus to form ore deposits. Recent year studies on liquid crystal materials hane convinced the author that consideralle physiological behaviors of phosphorus-thirsty microorganism, i. e. the preferential extraction, accumulation and transportation of phosphates, may be attributed to the liquid crystal form of the tissues and cells of phosphorus-thirsty microorganism
1985, 3(3): 23-31.
Abstract:
The paper covers eight families and ten species of trace fossils in the non-marine turbidite deposits of the Lower Jurassic age from the Jiyuan-Yima district, western Henan, among which two families and three species are new. And trace fossils of typical deep-water types such as Paleodictyon and Protopaleodictyon were discovered for the first time in fresh-water lake basins. It is of great significance to study non-marine ichnofacies model by means of the established marine ichnofacies model. Jiyuan flysch, which is between the Danaeopsis-Bernoullia flora of the Upper Triassic and Coniopteris-Phoenicopsis flora of the Middle Jurassic, is about 105m in thickness and is divided into upper, middle and lower parts. The three parts of the flysch consist of different types of ichnofossils, showing that the environment of Jiyuan-Yima fault basin changed rapidly due to the accumulatin of the sediments coming from the surrounding highland. The lower part of non-marine flysch is 18.3m thick, it contains 63 Bouma Sequences and is mainly composed of facies C. The grains becomes gradually coarse from below to above. The patterned trace fossils such as Paleodictyon, Protopaleodictyon may suggest that they were formed in a condition of sublacustrine middle fan and probably represented the deepest water period when sublacustrine turbidity was at its earliest stage of sedimentation. The middle part of the flysch consists of Facies B2 ,C,D and E. Its thickness is 60m, including 156 Bouma Sequences. The grains become finer and finer from below to above. Trace fossils are abundant and diversity is high. There are some important trace fossils such as Jiyuanichnus, Paracanthorhaphe, Tuberculichnus, Sa-bularia and Protopaleodityon. The tracemarkers were active in sublacustrine network-like channels, including that the development of lake basin approached its middle stage. There are 146 Bouma Sequences with 26.7m in thickness in the upper part of Ji-yuan Flysch. Most of them are of Pattern De and Ce. No other categories have been found except Granularia and Chondrites. The absence of deep-water forms and low diversity may be considered as an evidence of the ending of turbidite deposition. The analysis of paleocurrent within the Jiyuan-Yima Basin indicates that the sediments in the northeastern part, e.g. Jiyuan Area, originated from the southwest and southeast alternately. The main transportation direction of the sediments in southwestern basin, i.e. Yima Area was from southwest to northeast. The ephemeral development of Jiyuan turdidite deposits has been recorded both in ichnology and sedimentology. The records in ichnology may imply that the tracemarkers living in the sublacustrine were quite sensitive to the changing environment caused by the rapid sediment accumulation. Thus their traces are good indicators in determining subenviroments.
The paper covers eight families and ten species of trace fossils in the non-marine turbidite deposits of the Lower Jurassic age from the Jiyuan-Yima district, western Henan, among which two families and three species are new. And trace fossils of typical deep-water types such as Paleodictyon and Protopaleodictyon were discovered for the first time in fresh-water lake basins. It is of great significance to study non-marine ichnofacies model by means of the established marine ichnofacies model. Jiyuan flysch, which is between the Danaeopsis-Bernoullia flora of the Upper Triassic and Coniopteris-Phoenicopsis flora of the Middle Jurassic, is about 105m in thickness and is divided into upper, middle and lower parts. The three parts of the flysch consist of different types of ichnofossils, showing that the environment of Jiyuan-Yima fault basin changed rapidly due to the accumulatin of the sediments coming from the surrounding highland. The lower part of non-marine flysch is 18.3m thick, it contains 63 Bouma Sequences and is mainly composed of facies C. The grains becomes gradually coarse from below to above. The patterned trace fossils such as Paleodictyon, Protopaleodictyon may suggest that they were formed in a condition of sublacustrine middle fan and probably represented the deepest water period when sublacustrine turbidity was at its earliest stage of sedimentation. The middle part of the flysch consists of Facies B2 ,C,D and E. Its thickness is 60m, including 156 Bouma Sequences. The grains become finer and finer from below to above. Trace fossils are abundant and diversity is high. There are some important trace fossils such as Jiyuanichnus, Paracanthorhaphe, Tuberculichnus, Sa-bularia and Protopaleodityon. The tracemarkers were active in sublacustrine network-like channels, including that the development of lake basin approached its middle stage. There are 146 Bouma Sequences with 26.7m in thickness in the upper part of Ji-yuan Flysch. Most of them are of Pattern De and Ce. No other categories have been found except Granularia and Chondrites. The absence of deep-water forms and low diversity may be considered as an evidence of the ending of turbidite deposition. The analysis of paleocurrent within the Jiyuan-Yima Basin indicates that the sediments in the northeastern part, e.g. Jiyuan Area, originated from the southwest and southeast alternately. The main transportation direction of the sediments in southwestern basin, i.e. Yima Area was from southwest to northeast. The ephemeral development of Jiyuan turdidite deposits has been recorded both in ichnology and sedimentology. The records in ichnology may imply that the tracemarkers living in the sublacustrine were quite sensitive to the changing environment caused by the rapid sediment accumulation. Thus their traces are good indicators in determining subenviroments.
1985, 3(3): 45-49.
Abstract:
urface textures of quartz sand in 9 bottom samples from this region were studied. 150 quartz sand grains ( 0.25-0.5mm ) were observed with the scanning electron microscope. Our research shows that the surface of quartz sand have the traces of chemical solution, chemical precipitation and mechanical crushing in the study area. In these surface textures, quartz sand grains with chemical solution are the most abundant, while quartz sand grains with chemical precipitation or mechanical crushing is also present. The surface solution textures of quartz sand may be divided into four kinds on the basis of their forms: 1 ) solution pits 2 ) solution grooves 3 ) solution pictures as flower form 4 ) regular solution deltoid pits. In these solution, texturs the first and second kinds are of shallow Solution and the third and fourth ones are of deep solution. The analysis of the surface textures of quartz sand shows that the depositional environment, with the bottom water temperature of 20-24t! and salinity of 32.8-34.6% is favorable to the formation of chemical solution surface textures. The occurrence of the quartz sand with mechanical crushing surface in the study area indecate that this area was a near shore area in the wlirm glacial period. Our study shows that most of quartz sand grains have a better roundness in the investigated area. Their roundness coefficient is 40-50.As the chemical solution textures are much developed on the surface of these quartz sand grains, the subrounded and rounded quartz sand grains were resulted from the high-energy hydraulic action and high-energychemical action.
urface textures of quartz sand in 9 bottom samples from this region were studied. 150 quartz sand grains ( 0.25-0.5mm ) were observed with the scanning electron microscope. Our research shows that the surface of quartz sand have the traces of chemical solution, chemical precipitation and mechanical crushing in the study area. In these surface textures, quartz sand grains with chemical solution are the most abundant, while quartz sand grains with chemical precipitation or mechanical crushing is also present. The surface solution textures of quartz sand may be divided into four kinds on the basis of their forms: 1 ) solution pits 2 ) solution grooves 3 ) solution pictures as flower form 4 ) regular solution deltoid pits. In these solution, texturs the first and second kinds are of shallow Solution and the third and fourth ones are of deep solution. The analysis of the surface textures of quartz sand shows that the depositional environment, with the bottom water temperature of 20-24t! and salinity of 32.8-34.6% is favorable to the formation of chemical solution surface textures. The occurrence of the quartz sand with mechanical crushing surface in the study area indecate that this area was a near shore area in the wlirm glacial period. Our study shows that most of quartz sand grains have a better roundness in the investigated area. Their roundness coefficient is 40-50.As the chemical solution textures are much developed on the surface of these quartz sand grains, the subrounded and rounded quartz sand grains were resulted from the high-energy hydraulic action and high-energychemical action.
1985, 3(3): 65-73.
Abstract:
The source rocks from the first,third and fourth sections of Shahejie formation of Zhanhua depression have been analyzed by PY-GC and PY-GC-MS in this study and a detective method of multiple ions is employed to determine the triterpanes and triterpenes in the source rocks. The pyro-chromatograms of the source rocks of Zhanhua depression show that the distribution of n-alkane/n-alkene doublets is broad and that the first section and third section of the Shahejie formation have a n-alkane/n-alkene doublet distribution with odd over even preference and higher Pr/Ph ratio. On the contrary,the pyro-chromatogram of the forth section has n-alkane/n-alkene doublet distribution with an even over odd prefeence and lower Pr/Ph ratio. Thus, the fourth section of Shahejie formation is suggested as a saline lake sedimentation with reducing environment and that these indexes, such as n-alkane/n-alkene doublets distribution and Pr/Ph ratio, etc., can be used as the criteria of a sedimentary envirnment. The PY-GC, PY-GC-MS chromatograms of the source rocks of Zhanhua depression show that the insoluble organic matters, such as prist-l-ene/n-C17, C30 Ho-pane, 17β(H(21α(H)/17α(H)21β(H), C27Hopane 17β(H)/17a(H) C27Hopene/C27 17α(H)Hopane, etc. decrease with increasing maturity of the samples, and that C31 Hopane, 17α(H)21β(H)22S/17α(H)21β(H) 22(R+S)% increase with increasing maturity of the samples/ As a result, they demonstrate that these parameters can be employed to measure the maturity of organic matters in sediment. However, the result of the present study has shown that PY-GC and PY-GC-MS are useful means to evaluate the deposition environment of source rocks and its maturity.
The source rocks from the first,third and fourth sections of Shahejie formation of Zhanhua depression have been analyzed by PY-GC and PY-GC-MS in this study and a detective method of multiple ions is employed to determine the triterpanes and triterpenes in the source rocks. The pyro-chromatograms of the source rocks of Zhanhua depression show that the distribution of n-alkane/n-alkene doublets is broad and that the first section and third section of the Shahejie formation have a n-alkane/n-alkene doublet distribution with odd over even preference and higher Pr/Ph ratio. On the contrary,the pyro-chromatogram of the forth section has n-alkane/n-alkene doublet distribution with an even over odd prefeence and lower Pr/Ph ratio. Thus, the fourth section of Shahejie formation is suggested as a saline lake sedimentation with reducing environment and that these indexes, such as n-alkane/n-alkene doublets distribution and Pr/Ph ratio, etc., can be used as the criteria of a sedimentary envirnment. The PY-GC, PY-GC-MS chromatograms of the source rocks of Zhanhua depression show that the insoluble organic matters, such as prist-l-ene/n-C17, C30 Ho-pane, 17β(H(21α(H)/17α(H)21β(H), C27Hopane 17β(H)/17a(H) C27Hopene/C27 17α(H)Hopane, etc. decrease with increasing maturity of the samples, and that C31 Hopane, 17α(H)21β(H)22S/17α(H)21β(H) 22(R+S)% increase with increasing maturity of the samples/ As a result, they demonstrate that these parameters can be employed to measure the maturity of organic matters in sediment. However, the result of the present study has shown that PY-GC and PY-GC-MS are useful means to evaluate the deposition environment of source rocks and its maturity.
1985, 3(3): 87-94.
Abstract:
The paper covers three aspects to redestuction and retransformation traces of quartz gravels. 1 Redestruction and retransformation traces result inevitablly from various geological actions after gravel accumulation. The non-transformed redestraction gravel is named by. the authors the Q-Q gravel, which is characterised by obvious destruction traces ( e. g. rift, etc. ) , scratchs on the surface and sharp edges without bluntness or roundness ( Fig. 2 ). After another geological action, if the sharp edge of the Q-Q gravel is abraded and becomes blunt or round, showing a. trace of retransformation, this type of gravels is named the Q-D gravel ( Fig. 4 ) . However, if there is no abrasion or an obviously partial abrasion with the original shape remained, it is named the Q-O gravel ( Fig. 1 3 ). Based on these st udies, it is found that the geological actions causing redestruction and retranstormation are tectonic movement, driftbed, glacial erosion, glacial split and scion action of plant roots, etc..The tectonic movement and driftbed are the main factions of redestruction and retransformation. 2 In the Quaternary sediment of the ancient Yishu River area, different types of quartz gravels of redestruction and retransformation are counted and the result shows in Table 1 and Fig. 1 . From which it is obviously that there are some changes in the gravel content of different types of the Upper, Middle and Low Pleistocene strata and with a triangle diagram ( Fig. 1 ) the authors .probed into the possibility of using the points and link lines of the OD-QD to determine the border between the Middle Pleistocene aad the Low Pleistocene. 3 Along with redestruction and retransformation, a great quantity of unstable materials in strata are eroded and the volumn of strata are rapidly reduced while the content of stable materials are relatively increased. Thus, the ore tenor of stable and valuble minerals is also correspondingly increased. By this way. in this ditrict are formed diamond sand deposits with the industrial value. According to the above studies, the authors have drown up a genesis model of diamond sand deposits ( Fing. 3 ) and based on the model the possibles research direction to diamond sand deposits in this district is given.
The paper covers three aspects to redestuction and retransformation traces of quartz gravels. 1 Redestruction and retransformation traces result inevitablly from various geological actions after gravel accumulation. The non-transformed redestraction gravel is named by. the authors the Q-Q gravel, which is characterised by obvious destruction traces ( e. g. rift, etc. ) , scratchs on the surface and sharp edges without bluntness or roundness ( Fig. 2 ). After another geological action, if the sharp edge of the Q-Q gravel is abraded and becomes blunt or round, showing a. trace of retransformation, this type of gravels is named the Q-D gravel ( Fig. 4 ) . However, if there is no abrasion or an obviously partial abrasion with the original shape remained, it is named the Q-O gravel ( Fig. 1 3 ). Based on these st udies, it is found that the geological actions causing redestruction and retranstormation are tectonic movement, driftbed, glacial erosion, glacial split and scion action of plant roots, etc..The tectonic movement and driftbed are the main factions of redestruction and retransformation. 2 In the Quaternary sediment of the ancient Yishu River area, different types of quartz gravels of redestruction and retransformation are counted and the result shows in Table 1 and Fig. 1 . From which it is obviously that there are some changes in the gravel content of different types of the Upper, Middle and Low Pleistocene strata and with a triangle diagram ( Fig. 1 ) the authors .probed into the possibility of using the points and link lines of the OD-QD to determine the border between the Middle Pleistocene aad the Low Pleistocene. 3 Along with redestruction and retransformation, a great quantity of unstable materials in strata are eroded and the volumn of strata are rapidly reduced while the content of stable materials are relatively increased. Thus, the ore tenor of stable and valuble minerals is also correspondingly increased. By this way. in this ditrict are formed diamond sand deposits with the industrial value. According to the above studies, the authors have drown up a genesis model of diamond sand deposits ( Fing. 3 ) and based on the model the possibles research direction to diamond sand deposits in this district is given.
1985, 3(3): 105-114.
Abstract:
Xiaotianjing manganese deposit,Heqing in west Yunnan occurs in the transitional zone of limestone ( T3Sn2-2 ) and mudstone (T3S.n2-1) of the Upper Triassic Sungkuei group. Its surface is pyrolusite which is gradually substituted by rhodoch-rosite along with the depth. The Mining area is a synclinal folding. Mineralizatin intermittently appears in the northeastern limb. Its distribution is not very homogeneous. The orebody is rich and thick, comparatively concentratted and better continuous in the southwestern limb. It is obviously controlled by the paleogeogreaphic environment. The orebody of forms presents the stratified mangnese deposit, lenticular pyrolusite, belt-shaped py rolusite. But only the stratified manganese 4eposit has the industrial value. The mineral composition is comparatively simple, ore minerals are mainly pyrolusite,rhodochrosite and psilomelane,next are manganite, braunite and a little manganese-calcite. Gangue minerals are calcite, chlorite quartz and clay minerals, etc. and associated with a small quantity of pyrite and magnetite. The content of pyrolusite is high (64.12-82.5% ), harmful components are very few, so it is a rich ore for chemical industry. On the average, rhodochrosite is therichest ( 39.39% ) , therefore it is a rich ore for metallurgical manganese. At present, manganese orebody extends along the trend or the strike the thickness of its tenor and its ore quality are comparatively stable. The long axis direction of oredody is NW55°-60°, its form is like a narrow basin. There are three zones from outside to inside, they are pyrolusite zone-rhodochrosite zone-non-orebody zone ( Figure 1 ). With regard to the gneesis of deposit, there are two different views. The first is based on the fact that the manganese orebody is held in the fissure, it is related to wall-rock alteration, and considered as hydrothermal deposit. The second is based on the control of the orebody strata, it is considered as a sedimentary deposit. The author agrees to the latter. He has proposed eight proxves. The division of sedimentary rocky phase, analysis of orebody zonality and investigation of rock and mineral identification indicate that after the deposition,the deposit was slightly metamorphic. This view is comparatively accord with the objective reality of this area. And the view of hydrothermal genesis is very difficult to explain satisfactorily a series of ore-forming features of manganese deposit. Moreover, it is also a controversial issue that pyrolusite is an orignal sediment or comes from rhodochrosite with secondary oxidation. The autthor agreed to the former and has proposed 4 proxves to demonstrate that most pyrolusite may be of original sedimentation, and not the secondary oxidation from rhodochrosite. To sum up, Xiaotianjing deposit is rich orebody with a little impurity, its quality is good, it is a rich ore for chemical industry and metallurgical industry. Its industrial value is comparatively high. It is of great realistic significance for expanding the regional search of orebody to understand clearly the genesis of deposit and the condition of enrichment.
Xiaotianjing manganese deposit,Heqing in west Yunnan occurs in the transitional zone of limestone ( T3Sn2-2 ) and mudstone (T3S.n2-1) of the Upper Triassic Sungkuei group. Its surface is pyrolusite which is gradually substituted by rhodoch-rosite along with the depth. The Mining area is a synclinal folding. Mineralizatin intermittently appears in the northeastern limb. Its distribution is not very homogeneous. The orebody is rich and thick, comparatively concentratted and better continuous in the southwestern limb. It is obviously controlled by the paleogeogreaphic environment. The orebody of forms presents the stratified mangnese deposit, lenticular pyrolusite, belt-shaped py rolusite. But only the stratified manganese 4eposit has the industrial value. The mineral composition is comparatively simple, ore minerals are mainly pyrolusite,rhodochrosite and psilomelane,next are manganite, braunite and a little manganese-calcite. Gangue minerals are calcite, chlorite quartz and clay minerals, etc. and associated with a small quantity of pyrite and magnetite. The content of pyrolusite is high (64.12-82.5% ), harmful components are very few, so it is a rich ore for chemical industry. On the average, rhodochrosite is therichest ( 39.39% ) , therefore it is a rich ore for metallurgical manganese. At present, manganese orebody extends along the trend or the strike the thickness of its tenor and its ore quality are comparatively stable. The long axis direction of oredody is NW55°-60°, its form is like a narrow basin. There are three zones from outside to inside, they are pyrolusite zone-rhodochrosite zone-non-orebody zone ( Figure 1 ). With regard to the gneesis of deposit, there are two different views. The first is based on the fact that the manganese orebody is held in the fissure, it is related to wall-rock alteration, and considered as hydrothermal deposit. The second is based on the control of the orebody strata, it is considered as a sedimentary deposit. The author agrees to the latter. He has proposed eight proxves. The division of sedimentary rocky phase, analysis of orebody zonality and investigation of rock and mineral identification indicate that after the deposition,the deposit was slightly metamorphic. This view is comparatively accord with the objective reality of this area. And the view of hydrothermal genesis is very difficult to explain satisfactorily a series of ore-forming features of manganese deposit. Moreover, it is also a controversial issue that pyrolusite is an orignal sediment or comes from rhodochrosite with secondary oxidation. The autthor agreed to the former and has proposed 4 proxves to demonstrate that most pyrolusite may be of original sedimentation, and not the secondary oxidation from rhodochrosite. To sum up, Xiaotianjing deposit is rich orebody with a little impurity, its quality is good, it is a rich ore for chemical industry and metallurgical industry. Its industrial value is comparatively high. It is of great realistic significance for expanding the regional search of orebody to understand clearly the genesis of deposit and the condition of enrichment.
1985, 3(3): 125-129.
Abstract:
The terrigenous clastic sedimentary rock is absolute majority in the coaly sedimentary series, its grain-size texture is mixed.with various degrees of matrixes. When the sediments transtorm from the transportation of high-energy environment into lower-energy environment, the carriers of higigh-energy make soil and sand deposit, so that the clastic sedments within grainsize of matrix ( 0.03mm≈5φ)-may easily mix up with coarser grain texrture, In this paper, the author uses the examples of the features of fluvial environment from Qinghai Muli coal field, to explain the close relations between the matrix mixed and medium energy and micro-facies environmet control. It is suggested that using thematrixes the nomenclature of the terrigenous clastic sedimentary rock, does not effect on classification but only on nomenclature, The rock with 10-20% matrix is named x x x rock of matrix, The rock with 25-50% matrix is uamed matrix quality x x x x rock. In the basic nomenclature of tarrigenous clastic sedimentary rock, the terms matrixand matrix qualityare used to describe the difference of the mixed amout-and the degrees of matrix, so that they may be easily applied in worke. In addition, the author proposes a preliminary view of the differences between matrixes and cements for the terrigenous clastic sedimentarg rockrefromed by virtue of temperature, pressure and structure,.
The terrigenous clastic sedimentary rock is absolute majority in the coaly sedimentary series, its grain-size texture is mixed.with various degrees of matrixes. When the sediments transtorm from the transportation of high-energy environment into lower-energy environment, the carriers of higigh-energy make soil and sand deposit, so that the clastic sedments within grainsize of matrix ( 0.03mm≈5φ)-may easily mix up with coarser grain texrture, In this paper, the author uses the examples of the features of fluvial environment from Qinghai Muli coal field, to explain the close relations between the matrix mixed and medium energy and micro-facies environmet control. It is suggested that using thematrixes the nomenclature of the terrigenous clastic sedimentary rock, does not effect on classification but only on nomenclature, The rock with 10-20% matrix is named x x x rock of matrix, The rock with 25-50% matrix is uamed matrix quality x x x x rock. In the basic nomenclature of tarrigenous clastic sedimentary rock, the terms matrixand matrix qualityare used to describe the difference of the mixed amout-and the degrees of matrix, so that they may be easily applied in worke. In addition, the author proposes a preliminary view of the differences between matrixes and cements for the terrigenous clastic sedimentarg rockrefromed by virtue of temperature, pressure and structure,.
1985, 3(3): 7-22.
Abstract:
The region of west Hunan and east Guizhou is at the northwestern border of the Cambrian marginal sea in south China.In this region a deep-water carbonate slope with tendency southwestward had developed since Qingxudong period of Early Cambrian. A huge carbonate platform was present at the northwestern side of the slope and a deep-water basin lay at the southeastern lateral. Many types of carbonate rocks resedimented by gravity were formed at the deep-water area of the basin margin. Based on the textures and sedimentary structures, they were identified as: 1 ) isolated rock-block 2 )sliding and slumping deposits and 3 ) gravity flow sediments including debris flow, turbidity current and grain flow deposits. They commonly occur in the Middle and Upper Cambrian and their maximum cumulative-thickness is above 400m. A particular association of the slope deposits consists of gravity-displaced sediments interbedding autochthonous sediments, the majority of which is laminated carbonate mudstone. Of all gravity-displaced carbonate rocks, debris flow and turbidity current sediments are of most significance in both thickness and distribution. Debris flow sediments being full of calcirudites and boulders, mostly belong to submarine channel-filled deposits on the slope, they stretch southeastward in banded form, namely perpendicularly to the trend of the slope. The layer of calcirudite, the thickness of individual bed and grain size of sediments decrease apparently toward basin margin; but sebimentary bodies by debris flow extend more like sheet at the end of channels. There are two types of turbidites; 1 ) one formed by low-density suspension and 2 ) the other formed by high-density suspension. The former is relatively thin ( 10 cm) in the thickness of each layer, and fine (at most 3mm in grain size), characterized by regular grading) it occurs in the complete or incomplete Bouma sequences, and can be found in various sub-environments in the deep-water basin. The later is relatively thick ( 20 cm), and coarse (max. grain size up to 8 cm)) characterized by coarse-tail grading, paralle-bedding and intermidiate or large-scale cross-bedding intervals, which are frequently combined with each other to comsti-tute the equivalent of a-b-c incomplete Bouma sepuence. One grain flow sedimentary unit always consists of three intervals one after another, gradually from the lower to the upper: 1 ) reverse grading, 2 ) massive, in which the mean grain size of sediments is the largest, and 3 ) normal grading; it has another important feature that there is almost no matrix but sparry cement of generation in the voids between grains. Isolated rock-blocks, from shallow-water environments of carbonate platform margin, are huge rock-fragments of shelf edge reefs built by Cyanophyta ( Epiphy-ion, Girvanella, etc. ) j enclosed by dark-coloured, fine and thin-laminated carbonate mudstonej the volume of fragments is over ten thousand m they are mainly deposited in the middle of the slope. The sequence of sliding and slumping deposits, four endmembers of which are sediments with curved-lamination, sedimentary folds, faults sedimentary in origin, and autobreecia, is a reliable indicator of the palaeoslope. The cumulative-frequency curves ( in probability scale ) of three types of gravity flow sediments have their own characteristics respectively) and on the scatter plots of grain-size parameters it is easy to distinguish debris flow from two other types) but on the main-factor loading plot in correspondence analysis by computer, three types can be differentiated more easily from one another, despite of some overlap) and on the C-M plot not only the distribution of the three types can be shown in the band-shaped area parallel to c = m line, but also their sorting degrees by Im values. Bathymetric-palaeowater maps by the thickness-stratum method for calculation of water depth indicate that, theslope is 1°- 4° gradient, the depth 20-600 nij the basinal-margin rise 20'-40', 600-800m) the basinplain 8 '-20', 800m, Palaeocurrent direction w
The region of west Hunan and east Guizhou is at the northwestern border of the Cambrian marginal sea in south China.In this region a deep-water carbonate slope with tendency southwestward had developed since Qingxudong period of Early Cambrian. A huge carbonate platform was present at the northwestern side of the slope and a deep-water basin lay at the southeastern lateral. Many types of carbonate rocks resedimented by gravity were formed at the deep-water area of the basin margin. Based on the textures and sedimentary structures, they were identified as: 1 ) isolated rock-block 2 )sliding and slumping deposits and 3 ) gravity flow sediments including debris flow, turbidity current and grain flow deposits. They commonly occur in the Middle and Upper Cambrian and their maximum cumulative-thickness is above 400m. A particular association of the slope deposits consists of gravity-displaced sediments interbedding autochthonous sediments, the majority of which is laminated carbonate mudstone. Of all gravity-displaced carbonate rocks, debris flow and turbidity current sediments are of most significance in both thickness and distribution. Debris flow sediments being full of calcirudites and boulders, mostly belong to submarine channel-filled deposits on the slope, they stretch southeastward in banded form, namely perpendicularly to the trend of the slope. The layer of calcirudite, the thickness of individual bed and grain size of sediments decrease apparently toward basin margin; but sebimentary bodies by debris flow extend more like sheet at the end of channels. There are two types of turbidites; 1 ) one formed by low-density suspension and 2 ) the other formed by high-density suspension. The former is relatively thin ( 10 cm) in the thickness of each layer, and fine (at most 3mm in grain size), characterized by regular grading) it occurs in the complete or incomplete Bouma sequences, and can be found in various sub-environments in the deep-water basin. The later is relatively thick ( 20 cm), and coarse (max. grain size up to 8 cm)) characterized by coarse-tail grading, paralle-bedding and intermidiate or large-scale cross-bedding intervals, which are frequently combined with each other to comsti-tute the equivalent of a-b-c incomplete Bouma sepuence. One grain flow sedimentary unit always consists of three intervals one after another, gradually from the lower to the upper: 1 ) reverse grading, 2 ) massive, in which the mean grain size of sediments is the largest, and 3 ) normal grading; it has another important feature that there is almost no matrix but sparry cement of generation in the voids between grains. Isolated rock-blocks, from shallow-water environments of carbonate platform margin, are huge rock-fragments of shelf edge reefs built by Cyanophyta ( Epiphy-ion, Girvanella, etc. ) j enclosed by dark-coloured, fine and thin-laminated carbonate mudstonej the volume of fragments is over ten thousand m they are mainly deposited in the middle of the slope. The sequence of sliding and slumping deposits, four endmembers of which are sediments with curved-lamination, sedimentary folds, faults sedimentary in origin, and autobreecia, is a reliable indicator of the palaeoslope. The cumulative-frequency curves ( in probability scale ) of three types of gravity flow sediments have their own characteristics respectively) and on the scatter plots of grain-size parameters it is easy to distinguish debris flow from two other types) but on the main-factor loading plot in correspondence analysis by computer, three types can be differentiated more easily from one another, despite of some overlap) and on the C-M plot not only the distribution of the three types can be shown in the band-shaped area parallel to c = m line, but also their sorting degrees by Im values. Bathymetric-palaeowater maps by the thickness-stratum method for calculation of water depth indicate that, theslope is 1°- 4° gradient, the depth 20-600 nij the basinal-margin rise 20'-40', 600-800m) the basinplain 8 '-20', 800m, Palaeocurrent direction w
1985, 3(3): 33-44.
Abstract:
The Yangquan coal distrct is located in the eastern part of Shanxi. It's area is about 275 km2 and coal resources are rich there. It is one of the main coal bases in China. The main coal-bearing formations in this area——Taiyuan Group and Shanxi Formation are of Permo-Carboniferous in age. The Carboniferous Taiyuan Group which consists mainly of grey and dark-grey limestones, argillites, sandy-argillites, sandstones, tuffs, tuffites and coal seams, is about 120m in thickness. It contains 4 -9 coal seams, and the Coal Seam No. 15 at the bottom of this group is the main mai-nable one. The Permian Shanxi formation overlaying Taiyuan Group in succession is about 65 meters in thickness and is composed mainly of grey sandstones, dark-grey sandy-argillites, argillites, carbonaceous shales and coal seams. There are some lens of limestones in the lower part of the formarion. Shanxi Formation contains 6 coal seams, the No. 3 of which in the main minable one. The present study shows that the coal-bearing series at the Permo-carboniferous in this district mainly consists of coastal plain, delta and interdelta deposits. The Lowe- Upper Carboniferous in this district like the Upper-Middle Carboniferous is also characterized by gulf depositions. The coal district is located at the northern margin of the gulf. The foreshore spread toward south as sea water regressed southward, and the kj sheet sandstone body deposited, above which siltstones deposited succesively at tidal flat and the Coal Seam No.15 was formed in the peat swamp. Since the Coal Seam No.15 was formed in the brackish-water swamp at the coastal plain, the swamp for the accumulation of coal materials was spacious and stable for a long time, thus the thick and stable coal seam was formed in extensive area. As the environment, in which the coal was formed, was influenced largely by sea water or brackish water, the ash content of the Coal Seam No. 15 is low and the sulphur content is high. After the Coal Seam No.15 had been formed, this region was transgressed by the sea and the "Sijieshi" limestone deposited, above which subsequently, an up- ward coarser deltaic deposition sequence was formed, and there occurred a sea invasion afterward, thus the "Qianshi" limestonewas deposited. Between "Qianshi" and "Houshi" limestones are interdelta deposits. The deposits between the top of "Houshi" limestone and the Coal Seam No. 8 are formed in the shallow water delta. The section from the Coal Seam No. 8 to the bottom of Shanxi Formation is represented by an intact series of delta deposits. Shanxi Formation is composed of delta deposits developed succesively from the top of Taiyuan Group, which is represented by the prodelta and delta-front deposits. The deltaic depositional series also underwent a process of construction-destruction-construction. The section from the roof sandstone of the Coal Seam No. 6 to the Coal Seam No. 3 is made up of destructional delta deposits. After the accumulation of the roof sandstone of the Coal Seam No. 3 , the delta was under the constructional stage and accumulated deposits of distributary river channel, natural levee, burst-fan, valley flat and flood lake. The Coal Seam No. 3 of Shanxi Formation was formed at an abandoned delta flower which is a main minable seam. The stable environment continued to exist for a long time, thus providing an ideal space for accumulation of the Coal Seam No. 3, which was formed in an extensive area. To sum up, all the above-mentioned suggests that the deposits of Shanxi Formation are not "pure continental" as considered by most geologists in the past.
The Yangquan coal distrct is located in the eastern part of Shanxi. It's area is about 275 km2 and coal resources are rich there. It is one of the main coal bases in China. The main coal-bearing formations in this area——Taiyuan Group and Shanxi Formation are of Permo-Carboniferous in age. The Carboniferous Taiyuan Group which consists mainly of grey and dark-grey limestones, argillites, sandy-argillites, sandstones, tuffs, tuffites and coal seams, is about 120m in thickness. It contains 4 -9 coal seams, and the Coal Seam No. 15 at the bottom of this group is the main mai-nable one. The Permian Shanxi formation overlaying Taiyuan Group in succession is about 65 meters in thickness and is composed mainly of grey sandstones, dark-grey sandy-argillites, argillites, carbonaceous shales and coal seams. There are some lens of limestones in the lower part of the formarion. Shanxi Formation contains 6 coal seams, the No. 3 of which in the main minable one. The present study shows that the coal-bearing series at the Permo-carboniferous in this district mainly consists of coastal plain, delta and interdelta deposits. The Lowe- Upper Carboniferous in this district like the Upper-Middle Carboniferous is also characterized by gulf depositions. The coal district is located at the northern margin of the gulf. The foreshore spread toward south as sea water regressed southward, and the kj sheet sandstone body deposited, above which siltstones deposited succesively at tidal flat and the Coal Seam No.15 was formed in the peat swamp. Since the Coal Seam No.15 was formed in the brackish-water swamp at the coastal plain, the swamp for the accumulation of coal materials was spacious and stable for a long time, thus the thick and stable coal seam was formed in extensive area. As the environment, in which the coal was formed, was influenced largely by sea water or brackish water, the ash content of the Coal Seam No. 15 is low and the sulphur content is high. After the Coal Seam No.15 had been formed, this region was transgressed by the sea and the "Sijieshi" limestone deposited, above which subsequently, an up- ward coarser deltaic deposition sequence was formed, and there occurred a sea invasion afterward, thus the "Qianshi" limestonewas deposited. Between "Qianshi" and "Houshi" limestones are interdelta deposits. The deposits between the top of "Houshi" limestone and the Coal Seam No. 8 are formed in the shallow water delta. The section from the Coal Seam No. 8 to the bottom of Shanxi Formation is represented by an intact series of delta deposits. Shanxi Formation is composed of delta deposits developed succesively from the top of Taiyuan Group, which is represented by the prodelta and delta-front deposits. The deltaic depositional series also underwent a process of construction-destruction-construction. The section from the roof sandstone of the Coal Seam No. 6 to the Coal Seam No. 3 is made up of destructional delta deposits. After the accumulation of the roof sandstone of the Coal Seam No. 3 , the delta was under the constructional stage and accumulated deposits of distributary river channel, natural levee, burst-fan, valley flat and flood lake. The Coal Seam No. 3 of Shanxi Formation was formed at an abandoned delta flower which is a main minable seam. The stable environment continued to exist for a long time, thus providing an ideal space for accumulation of the Coal Seam No. 3, which was formed in an extensive area. To sum up, all the above-mentioned suggests that the deposits of Shanxi Formation are not "pure continental" as considered by most geologists in the past.
1985, 3(3): 51-64.
Abstract:
Different clay mineral assemblages and their replacement have been formed in different sedimentary and diagenetic environments in the western depression ( Huan-xiling, Xinglongtai and Maquanzhi ): 1.Montmorillonite-I/M-illite-kaolinite mineral assemblage 2.1/M-authigenic illite-atlthigenic chiorite mineral assemblage The weak acidic and weak alkaline environments were transformed into slight alkaine-weak reductive ones with the increase of depth and geothermal and mont-morillonite and I/M turned into illite and trioctahedron chlorite. In the north region of the western depression ( Gaosheng and the local area of Shuguang)t 1. I/M-illie mineral assemblage 2. Glauconite-trioctahedron smectite mineral assemblage 3. Fe-saponite mineral The Sha-4 stage in the area was a slight alkaline-weak reductive sedimentary environment without kaolinite mineral and Ca, Fe3 + Fe2+and Mg were rich in the environment due to the degeneration of the secondary saponite from basalt into trio-dioctahedron smectite. Together with Fe and Mg, K and Al supplied by solubilized K and Al-bearing terrigenous minerals under the higher geothermal moved into I/M crystal lattices and thus forming glauconite. The evidence of mineralogy has shown that the geochemical properties of the sedimentary and diagenetic environments are the principal factors which control low-temperature geochemial behaviors of clay minerals during the diagenesis, and secondly, the temperature also plays an important part during the diagenesis of clay minerals.
Different clay mineral assemblages and their replacement have been formed in different sedimentary and diagenetic environments in the western depression ( Huan-xiling, Xinglongtai and Maquanzhi ): 1.Montmorillonite-I/M-illite-kaolinite mineral assemblage 2.1/M-authigenic illite-atlthigenic chiorite mineral assemblage The weak acidic and weak alkaline environments were transformed into slight alkaine-weak reductive ones with the increase of depth and geothermal and mont-morillonite and I/M turned into illite and trioctahedron chlorite. In the north region of the western depression ( Gaosheng and the local area of Shuguang)t 1. I/M-illie mineral assemblage 2. Glauconite-trioctahedron smectite mineral assemblage 3. Fe-saponite mineral The Sha-4 stage in the area was a slight alkaline-weak reductive sedimentary environment without kaolinite mineral and Ca, Fe3 + Fe2+and Mg were rich in the environment due to the degeneration of the secondary saponite from basalt into trio-dioctahedron smectite. Together with Fe and Mg, K and Al supplied by solubilized K and Al-bearing terrigenous minerals under the higher geothermal moved into I/M crystal lattices and thus forming glauconite. The evidence of mineralogy has shown that the geochemical properties of the sedimentary and diagenetic environments are the principal factors which control low-temperature geochemial behaviors of clay minerals during the diagenesis, and secondly, the temperature also plays an important part during the diagenesis of clay minerals.
1985, 3(3): 74-85.
Abstract:
Four depositional characteristics of coarse clastic alluvial fans have been recognized in the investigations performed on recent and ancient fans in Xinjiang.Such features have not ,been paid attention to,or even never been described in previous literatures.These depositional characteristics arc of significance for identification of coarse clastic fans,especially the ancient one and that duried in subground sediments. Therefore, such uniQue characteristics can be used as depositional facies indicators. 1 ) Alluvial sidiment bedding: Stratified structure formed from thin to moderate thick, aggradated and overlapped alluvial sediments.Vertically, such stratified structure appears as a number of sand and gravel or pebble strata occur alternatively, while no distinct, regular bedding plane can be observed. 2 ) Propping conglomerate; It is a loose packed gravel or pebble bed occurring in alluvial fan sediments and characterized by the mutual prop of pebbles with rather good sorting, it can not be consolideted by cementation, due to rare or absent sandy/ argillaceous infilling matericals in pore spaces. 3 ) Funnel-like electrolog response. 4 ) Normal probability cumulative curves of grain size characterized by wide range of grain size distribution and gentle slope of curve. The origin, property and distribution of these characteristics mentioned above have been stated in this paper. Furthermore,the differences between the propping conglomerate and sieve sediments, alluvial bedding and parallel stratification, as well as that between the type "A"electrolog curve of coarce clastic alluvial fan and that of the frontal fringe facies of delta have been described. Due to the different conditions of topography and hydrokinetic, the sediments located in different parts of the coarse clastic alluvial fan are different, unique features, which will affect the development of hydrocarbon reservoir and aquifer of the alluvial fan. The second part of this paper presents a microfacies subdivision system of alluvial fan,based on investigation made on recent alluial fan and that of the Middle Triassic in Karamay oilfield. The alluvial fan may be divided into three subfacies and subdivided into several microfacies as follows: 1 ) Fan top subfacies zone including four microfacies, namely the main ravine, lateral margin ravine, flood zone and ravine bank. 2 ) Mid-fan subfacies zone including three microfacies, namely the braided stream, braided sand island and flood flow zone. 3 ) Fan margin subfacies zone. Again, the inter-fan zone between two adjacent fans may be subdivided into two microfacies, namely the inter-fan bank and the inter-fan depression. All the involved depositional features have been described in this paper respectively. The investigations have proved that the application of such subdivision and delineation system of coarse clastic alluvial fan may be to development studies on such reservoirs h籿e obtained better results.
Four depositional characteristics of coarse clastic alluvial fans have been recognized in the investigations performed on recent and ancient fans in Xinjiang.Such features have not ,been paid attention to,or even never been described in previous literatures.These depositional characteristics arc of significance for identification of coarse clastic fans,especially the ancient one and that duried in subground sediments. Therefore, such uniQue characteristics can be used as depositional facies indicators. 1 ) Alluvial sidiment bedding: Stratified structure formed from thin to moderate thick, aggradated and overlapped alluvial sediments.Vertically, such stratified structure appears as a number of sand and gravel or pebble strata occur alternatively, while no distinct, regular bedding plane can be observed. 2 ) Propping conglomerate; It is a loose packed gravel or pebble bed occurring in alluvial fan sediments and characterized by the mutual prop of pebbles with rather good sorting, it can not be consolideted by cementation, due to rare or absent sandy/ argillaceous infilling matericals in pore spaces. 3 ) Funnel-like electrolog response. 4 ) Normal probability cumulative curves of grain size characterized by wide range of grain size distribution and gentle slope of curve. The origin, property and distribution of these characteristics mentioned above have been stated in this paper. Furthermore,the differences between the propping conglomerate and sieve sediments, alluvial bedding and parallel stratification, as well as that between the type "A"electrolog curve of coarce clastic alluvial fan and that of the frontal fringe facies of delta have been described. Due to the different conditions of topography and hydrokinetic, the sediments located in different parts of the coarse clastic alluvial fan are different, unique features, which will affect the development of hydrocarbon reservoir and aquifer of the alluvial fan. The second part of this paper presents a microfacies subdivision system of alluvial fan,based on investigation made on recent alluial fan and that of the Middle Triassic in Karamay oilfield. The alluvial fan may be divided into three subfacies and subdivided into several microfacies as follows: 1 ) Fan top subfacies zone including four microfacies, namely the main ravine, lateral margin ravine, flood zone and ravine bank. 2 ) Mid-fan subfacies zone including three microfacies, namely the braided stream, braided sand island and flood flow zone. 3 ) Fan margin subfacies zone. Again, the inter-fan zone between two adjacent fans may be subdivided into two microfacies, namely the inter-fan bank and the inter-fan depression. All the involved depositional features have been described in this paper respectively. The investigations have proved that the application of such subdivision and delineation system of coarse clastic alluvial fan may be to development studies on such reservoirs h籿e obtained better results.
1985, 3(3): 95-104.
Abstract:
The Quaternary red clays which may probably belong to respective sedimentary facies are widely dispersed in South China. The period of the Quaternary red clays has been divided in middle Pleistocene ( Q 2 ) . They are charecterized by red color, clayey texture, mottling in the bottom layer and boulder in the lower part. According to the geomorphology, the genesis and origin of materials, the Quaternary red clay sediments in the Taihe region,Jiangxi Province, may be divided into two types; one ( profile 1 , 2 ) is dark red material of residual and slope deposits of early middle Pleistocene which sedimented earlierj the other ( profile 3,4) is light red alluvial material,which sedimented later, Both of them have undergone-a soil-forming process since middle Pleistocene until now. It can be seen from the composition of heavy minerals in-the 10-50 μm fractions that the dark red clay sediments contain 7 -10% hornblende and 17-20% tourmaline, while the contents of the two minerals in light red ones are 17-22% and 9-14% respectively. It can also be seen from the composition of the minerals of the2μm fractions that the dark red sediments have little more kaolinite and free iron oxides, less 14λ transitional minerals and noncrystalline materials than the light red ones.The activity of free iron oxide, the dispersity and specific surface area are greater in 'light red sediments than those in dark red ones. The X-ray diffraction patterns of the clay particles in mottling layer ofter the treatment of removing iron indicate that the mineral composition in mottling layer ( 2μ) is similar to the soil in the upper layer and that the difference in the colour of the mottles only reflects the various contents of free iron oxide. According to the study of mineralogy, there is a difference in the degree of weathering and soil forming between the two sediments of Quaternary red clays,the weathering degree of dark red sediments is greater than that in the other. The red clay must be compared with the soils which were developed from igneous rock, when a thorough investigation is made,
The Quaternary red clays which may probably belong to respective sedimentary facies are widely dispersed in South China. The period of the Quaternary red clays has been divided in middle Pleistocene ( Q 2 ) . They are charecterized by red color, clayey texture, mottling in the bottom layer and boulder in the lower part. According to the geomorphology, the genesis and origin of materials, the Quaternary red clay sediments in the Taihe region,Jiangxi Province, may be divided into two types; one ( profile 1 , 2 ) is dark red material of residual and slope deposits of early middle Pleistocene which sedimented earlierj the other ( profile 3,4) is light red alluvial material,which sedimented later, Both of them have undergone-a soil-forming process since middle Pleistocene until now. It can be seen from the composition of heavy minerals in-the 10-50 μm fractions that the dark red clay sediments contain 7 -10% hornblende and 17-20% tourmaline, while the contents of the two minerals in light red ones are 17-22% and 9-14% respectively. It can also be seen from the composition of the minerals of the2μm fractions that the dark red sediments have little more kaolinite and free iron oxides, less 14λ transitional minerals and noncrystalline materials than the light red ones.The activity of free iron oxide, the dispersity and specific surface area are greater in 'light red sediments than those in dark red ones. The X-ray diffraction patterns of the clay particles in mottling layer ofter the treatment of removing iron indicate that the mineral composition in mottling layer ( 2μ) is similar to the soil in the upper layer and that the difference in the colour of the mottles only reflects the various contents of free iron oxide. According to the study of mineralogy, there is a difference in the degree of weathering and soil forming between the two sediments of Quaternary red clays,the weathering degree of dark red sediments is greater than that in the other. The red clay must be compared with the soils which were developed from igneous rock, when a thorough investigation is made,
1985, 3(3): 115-124.
Abstract:
In this paper, the types, composition, distribution and origin of the main clay minerals of sadiments in the middle of the Pleific Oeean are initially analysed and studied, -which offers an important insight into the understanding of the sediments in respect to their origin, transport, environment and history. The clay minerals are mainly dioctahedral Fe-Al montmorillonite characterized by its broad crystalliaityj trioctahedral Fe-Mg chlorite,some of which are good in their crystallinity, but some poor; dioctahedral Fe-Al hydromica ( illite ) of muscovite type, having the stable properties of crystallo-chemistrys kaolinite with a property of chanegeable order,including the highly-ordered and double-layer dickite and poorly-ordered kaolinite as well as some mixed-layer ones, such as illite-montmoril-lonite, illite-chlorite and kaolinite-montmorillonite and palygorskite in small amount. Among clay minerals, the montmorillonite and chlorite are mainly authigenic, and the muscovite and kaolinite are mainly terrigenous origin from Australia. During the chilly glacial epoch, the sea level fell and the tein perature of the sea water reduced.Meanwhile the dissolution of the carbonate decreased, and the carbonate in the sediments was rich, while the total amount of the clay minerals was poor. In addition,the volcanic activites were quite violent and the sources of the basic volca-aic material were abundant, Therefore, the relative amount of the authigenic montmorillonite was bigger than that of the other clay minerals, and the ratio of montmorillonite to illite was relatively bigger. The situation of the interglacial anci the post-glacial ages was contrary to that of the glacial age.
In this paper, the types, composition, distribution and origin of the main clay minerals of sadiments in the middle of the Pleific Oeean are initially analysed and studied, -which offers an important insight into the understanding of the sediments in respect to their origin, transport, environment and history. The clay minerals are mainly dioctahedral Fe-Al montmorillonite characterized by its broad crystalliaityj trioctahedral Fe-Mg chlorite,some of which are good in their crystallinity, but some poor; dioctahedral Fe-Al hydromica ( illite ) of muscovite type, having the stable properties of crystallo-chemistrys kaolinite with a property of chanegeable order,including the highly-ordered and double-layer dickite and poorly-ordered kaolinite as well as some mixed-layer ones, such as illite-montmoril-lonite, illite-chlorite and kaolinite-montmorillonite and palygorskite in small amount. Among clay minerals, the montmorillonite and chlorite are mainly authigenic, and the muscovite and kaolinite are mainly terrigenous origin from Australia. During the chilly glacial epoch, the sea level fell and the tein perature of the sea water reduced.Meanwhile the dissolution of the carbonate decreased, and the carbonate in the sediments was rich, while the total amount of the clay minerals was poor. In addition,the volcanic activites were quite violent and the sources of the basic volca-aic material were abundant, Therefore, the relative amount of the authigenic montmorillonite was bigger than that of the other clay minerals, and the ratio of montmorillonite to illite was relatively bigger. The situation of the interglacial anci the post-glacial ages was contrary to that of the glacial age.
