1989 Vol. 7, No. 3
column
Display Method:
1989, 7(3): 11-20.
Abstract:
Yangzi Platform was a relatively active platform- It includes deposits of both the stable areas and the transition areas. Laterally, there are two different sedimentary formation areas in eastern and the western parts. The paragenetic bodies of rocks, which were formed in different type of sedimentary areas of in different stages of same area, can be divided into four major sub-formation; phosphorite-bearing carbonate, phosphorite-bearing elastic rock, salt-gupsum一bearing carbonate (or carbonate) and phosphoritebearing silica-mudstone sub-formation. The distribution of Cambrian sedimentary formation in Yangzi Platform u as closely related to crust movement, tectonic settings and paleogeography. Sedimentary formation consisted of more than two types of rocks has occurred in western part of West Yangzi Platform; sedimentary formation consistd of only two types of rocks has been fo :nd in Zunyi, Meitan, liangkou and Xiushan, without phosphorite- bearing carbonate sub一formation; flysh formation has occurred in Zhixing and Youxian. Different petrological formation may be found in a same formation but、;:reed arcaa Carbonate sub-formatin in East Yangzi Platform, e.g., is apparently diloerent trom the west plan-o: m This was controlled by local geological settings. There is no evident reguilarity for the evlution of sedimentary formation. On the contary, it was varied from time to time. The thickness of Cambrian sediments m Yangzi platform varies in different places.It is thicker in the west platform than in the east which is an uncompensate basin. Lapping sedimentary centres of different stages of the platform together, we can see that they migrated in different ways according to different areas. Sedimentary centre in the West Yangzi Platform jumped from one plac to another through time. While the centre in the east platform lapped together during two sedimentary stages, showing that it is an inhernt depressing basin. In brief, the sdimentary formation types and the different development stage were association with crustal activity of the Cambrian in the Yangzi Platform. The formation and development of the sedimentary formation were influenced by paleoclimate, as well. The phosphorite-bearing carbonate sub-formation with higher economic value are always losated at the eastern and the western coast of paleocontinents, around ancient island and offshore riese with low paleolatitudes 3“一42“.As the ocean current carried the phosphorus-rich cold water to rise from depth, the warm and hot climate was favorable to the Separation and concentration of phosphatic materials. Large phosphorite deposits at home and abroad are mostly associated with very thick dolomite. thus far, it may be concluded that phosphorite-bearing carbonate sub-fromation were mostly formed under the paleoclimate condition of the transition period from cold to hot and from moist to dry, at low latitude (paleolatitude or modern latitude).
Yangzi Platform was a relatively active platform- It includes deposits of both the stable areas and the transition areas. Laterally, there are two different sedimentary formation areas in eastern and the western parts. The paragenetic bodies of rocks, which were formed in different type of sedimentary areas of in different stages of same area, can be divided into four major sub-formation; phosphorite-bearing carbonate, phosphorite-bearing elastic rock, salt-gupsum一bearing carbonate (or carbonate) and phosphoritebearing silica-mudstone sub-formation. The distribution of Cambrian sedimentary formation in Yangzi Platform u as closely related to crust movement, tectonic settings and paleogeography. Sedimentary formation consisted of more than two types of rocks has occurred in western part of West Yangzi Platform; sedimentary formation consistd of only two types of rocks has been fo :nd in Zunyi, Meitan, liangkou and Xiushan, without phosphorite- bearing carbonate sub一formation; flysh formation has occurred in Zhixing and Youxian. Different petrological formation may be found in a same formation but、;:reed arcaa Carbonate sub-formatin in East Yangzi Platform, e.g., is apparently diloerent trom the west plan-o: m This was controlled by local geological settings. There is no evident reguilarity for the evlution of sedimentary formation. On the contary, it was varied from time to time. The thickness of Cambrian sediments m Yangzi platform varies in different places.It is thicker in the west platform than in the east which is an uncompensate basin. Lapping sedimentary centres of different stages of the platform together, we can see that they migrated in different ways according to different areas. Sedimentary centre in the West Yangzi Platform jumped from one plac to another through time. While the centre in the east platform lapped together during two sedimentary stages, showing that it is an inhernt depressing basin. In brief, the sdimentary formation types and the different development stage were association with crustal activity of the Cambrian in the Yangzi Platform. The formation and development of the sedimentary formation were influenced by paleoclimate, as well. The phosphorite-bearing carbonate sub-formation with higher economic value are always losated at the eastern and the western coast of paleocontinents, around ancient island and offshore riese with low paleolatitudes 3“一42“.As the ocean current carried the phosphorus-rich cold water to rise from depth, the warm and hot climate was favorable to the Separation and concentration of phosphatic materials. Large phosphorite deposits at home and abroad are mostly associated with very thick dolomite. thus far, it may be concluded that phosphorite-bearing carbonate sub-fromation were mostly formed under the paleoclimate condition of the transition period from cold to hot and from moist to dry, at low latitude (paleolatitude or modern latitude).
1989, 7(3): 39-51.
Abstract:
The Lower Dainan Formation, Early Tertiary，of the Gaoyou Sub- Depression in the north Jiangsu Basin is a main oi-lbearing reservoirs, with the maximum thickness of more 800m in the central part of the basin. Core sample was systematically made from 22 wells in different depths from the west margin accross the studies area eastwards. Eased on detailed analysis of minerology, geochemistry, and rock physical properties. using the methods of thin section. SEM, pore casts, kerogen. and vitrinite retlectane, etc，the burial diagenetic chacteristics of sandstones are discussed. With burial deeping, the grains of quartz and feldspar and minor heavy minerals were dissolved, overgrown, pressuredissolved and replaced or altered. Carbonate cements occurred dissolution and replacment, and formed two different diagenctic mineral sertes in the shallower and deeper depths. According to constituent, aggregation, series of minerals in grain and cement. and properties and types of porosity, four distinct diagenetic zones can be divided:immature, low mature, mature I and mature II. Sandstone reservoirs have primary and secondary porosities, which control the distribution of physical parameters in the shallower and deeper reservoirs. respectively. In the shallower reservoir predomnantes primary porosity where occurred less dissolved secondary porosity relatively. With the increase of machanical compaction and chemical precipitation, the total porosity decrease gradually. The peak of carbonate precipitation occurred at 2800 m and form a high carbonatizicd sandstone zone and sametime the porosity tended to diminish. Helow the carbonatizied sandstone zone the secondary porosity became predominance with total porosity increase. The dissolution of silicates, carbonates and other salts is a major factor in generation of secondary porosity. Two important conditions of mineral dissolution are pIi of pore water and temperature. Twenty patterns of secondary porosity show aregular evolution of dissolution in various diagenetic environments. In the different depths two intensive secondary porosity zouec occurred caused by different origins.The first intensive secondary porosity gone ranges from 2950 to 3150 m in depth. and the face pore dcnsity can reach about 14%，which just coincides with the high vale ranges of radio of pristane over phy tape. hydrocarbon over organic carbon. It suggests that occurrence and development of the first intensive secon dary porosity zone is related to dcearboxylation and organic acids ieicase of kerogcn Crom associated mudstones during the early organic mature stage. Hy theoretical calculation, about 1.7-4.6% of new porosity could form by the dissolution of feldspar and carbonate resulting only from decarboxylation. This zone is a principal place of hydrocarbon primary migration and accumulates mainly low mature oil. The second intensive secondary porosity zone occurred from 3300 to 3650 m, with face pore density reaching about 16%.Its origin is closely related to the specific replacement reaction between feldspars,silica and dolomites. By theoretical calculation, These two reactions could produced C0168034g and 544278 and caused new dissolved porosity about 7.7% by dissolution of feldspars and calcites. The second intensive secondary porosity zone caused by inorganic reactions within the sandstoncs could accumulate high mature oil or condensates. which should be a potential site for oil and gas exploration in the deep depth.
The Lower Dainan Formation, Early Tertiary，of the Gaoyou Sub- Depression in the north Jiangsu Basin is a main oi-lbearing reservoirs, with the maximum thickness of more 800m in the central part of the basin. Core sample was systematically made from 22 wells in different depths from the west margin accross the studies area eastwards. Eased on detailed analysis of minerology, geochemistry, and rock physical properties. using the methods of thin section. SEM, pore casts, kerogen. and vitrinite retlectane, etc，the burial diagenetic chacteristics of sandstones are discussed. With burial deeping, the grains of quartz and feldspar and minor heavy minerals were dissolved, overgrown, pressuredissolved and replaced or altered. Carbonate cements occurred dissolution and replacment, and formed two different diagenctic mineral sertes in the shallower and deeper depths. According to constituent, aggregation, series of minerals in grain and cement. and properties and types of porosity, four distinct diagenetic zones can be divided:immature, low mature, mature I and mature II. Sandstone reservoirs have primary and secondary porosities, which control the distribution of physical parameters in the shallower and deeper reservoirs. respectively. In the shallower reservoir predomnantes primary porosity where occurred less dissolved secondary porosity relatively. With the increase of machanical compaction and chemical precipitation, the total porosity decrease gradually. The peak of carbonate precipitation occurred at 2800 m and form a high carbonatizicd sandstone zone and sametime the porosity tended to diminish. Helow the carbonatizied sandstone zone the secondary porosity became predominance with total porosity increase. The dissolution of silicates, carbonates and other salts is a major factor in generation of secondary porosity. Two important conditions of mineral dissolution are pIi of pore water and temperature. Twenty patterns of secondary porosity show aregular evolution of dissolution in various diagenetic environments. In the different depths two intensive secondary porosity zouec occurred caused by different origins.The first intensive secondary porosity gone ranges from 2950 to 3150 m in depth. and the face pore dcnsity can reach about 14%，which just coincides with the high vale ranges of radio of pristane over phy tape. hydrocarbon over organic carbon. It suggests that occurrence and development of the first intensive secon dary porosity zone is related to dcearboxylation and organic acids ieicase of kerogcn Crom associated mudstones during the early organic mature stage. Hy theoretical calculation, about 1.7-4.6% of new porosity could form by the dissolution of feldspar and carbonate resulting only from decarboxylation. This zone is a principal place of hydrocarbon primary migration and accumulates mainly low mature oil. The second intensive secondary porosity zone occurred from 3300 to 3650 m, with face pore density reaching about 16%.Its origin is closely related to the specific replacement reaction between feldspars,silica and dolomites. By theoretical calculation, These two reactions could produced C0168034g and 544278 and caused new dissolved porosity about 7.7% by dissolution of feldspars and calcites. The second intensive secondary porosity zone caused by inorganic reactions within the sandstoncs could accumulate high mature oil or condensates. which should be a potential site for oil and gas exploration in the deep depth.
1989, 7(3): 63-72.
Abstract:
River system such as Liaohe River, Hunhe River. Taizi River Dating River ctc.cntcrsinto Lower Liaohe Graben Basin form moutains, modeling the mst Lower Liaohe Plain and forming a series of buricdQuatcrnary alluvial fans on periphery area of the plain which arc perfect resources of supplyiyg water for Shcnyang, Anshan, Jinhou and othetr cities. Lower Liaohe Plain is a rift basi in Middle Cenozoic. Since Quaternary neotectonic movement is inhericed settle,The piedmont on periphery of the plain is strong place of tectonization. So the structural slope belt on the piedmont is the premise condition which buried alluvial tan is formed.The plain area not only has huge terrihenous elastic sediment(6000m一8000m) but also is the centre of Quaternary sediment in Liaoning province (more than 400m). Flowing out of mountain gaps, rivers form a series of large Quternary alluvial fans, there are Liaohc Fan. Hunhe Fan, Taizihe Fan, Dalinghe Fan. The area of only one fan is IOOOto 1500 spuare kilornctres, belong to large or middle-type.The shape and plane distribution of the fans are controlled by landform conditions which rivetrs flow out of mountain gaps.They usually distribute in the form of regular fan of tongue.The vertical shape of the alluvial fans is controlled by structure of basement.If the moutain gap has deep Fracture or step Fracture, the form of alluvial Fans is sphenoid or step; if the mountain gap is sagged slowly, the form is lens. The lithofacics structure of the alluvial fans have obvious horizontal banding.The body of fans can be further divided into sedimentary subfacies of top, middle and edge of fans according to the lithological characters, thickness and its space position.The study on grain size of sediment and electron microscope scanning of quart grain shows that dynamic mechanism of coarse elastic sediment on the top of Cans is strong hydrodynamism of rapids-type.The lithological characters of the top are gravel, grouan and sand which content is about 60-80 percent. the greatest thicknees is 100m, it is major place which water re- sources in city ezploitcd recently.The edge of fan is clay which content is 60-90 pocrcnt.Water in it is very little, so it has no meanihg of supplying water. These superposed alluvial fans formed from Late Middle Plcistoene of Late Pleistocene. The vertical variations of grain size data of the fans body reflects thqt dynamic state and sedimentary environment change with time,Φvalues of grain in Late Middle and Late Pleistocene is more coarse than in middle.lt shows that the climate was warm and the 17ow of river is large, it is the characters of flood pcriod, identical with the climate characters represntcd by data of sporo-pollen and panning.
River system such as Liaohe River, Hunhe River. Taizi River Dating River ctc.cntcrsinto Lower Liaohe Graben Basin form moutains, modeling the mst Lower Liaohe Plain and forming a series of buricdQuatcrnary alluvial fans on periphery area of the plain which arc perfect resources of supplyiyg water for Shcnyang, Anshan, Jinhou and othetr cities. Lower Liaohe Plain is a rift basi in Middle Cenozoic. Since Quaternary neotectonic movement is inhericed settle,The piedmont on periphery of the plain is strong place of tectonization. So the structural slope belt on the piedmont is the premise condition which buried alluvial tan is formed.The plain area not only has huge terrihenous elastic sediment(6000m一8000m) but also is the centre of Quaternary sediment in Liaoning province (more than 400m). Flowing out of mountain gaps, rivers form a series of large Quternary alluvial fans, there are Liaohc Fan. Hunhe Fan, Taizihe Fan, Dalinghe Fan. The area of only one fan is IOOOto 1500 spuare kilornctres, belong to large or middle-type.The shape and plane distribution of the fans are controlled by landform conditions which rivetrs flow out of mountain gaps.They usually distribute in the form of regular fan of tongue.The vertical shape of the alluvial fans is controlled by structure of basement.If the moutain gap has deep Fracture or step Fracture, the form of alluvial Fans is sphenoid or step; if the mountain gap is sagged slowly, the form is lens. The lithofacics structure of the alluvial fans have obvious horizontal banding.The body of fans can be further divided into sedimentary subfacies of top, middle and edge of fans according to the lithological characters, thickness and its space position.The study on grain size of sediment and electron microscope scanning of quart grain shows that dynamic mechanism of coarse elastic sediment on the top of Cans is strong hydrodynamism of rapids-type.The lithological characters of the top are gravel, grouan and sand which content is about 60-80 percent. the greatest thicknees is 100m, it is major place which water re- sources in city ezploitcd recently.The edge of fan is clay which content is 60-90 pocrcnt.Water in it is very little, so it has no meanihg of supplying water. These superposed alluvial fans formed from Late Middle Plcistoene of Late Pleistocene. The vertical variations of grain size data of the fans body reflects thqt dynamic state and sedimentary environment change with time,Φvalues of grain in Late Middle and Late Pleistocene is more coarse than in middle.lt shows that the climate was warm and the 17ow of river is large, it is the characters of flood pcriod, identical with the climate characters represntcd by data of sporo-pollen and panning.
1989, 7(3): 83-89.
Abstract:
In order to forecast, explore and cxplmt relative high quality coals,it is necessary to understand the law of sulphur and ash contents and the factor controlline the chanemg law.For this reason the study on the coal qualUy of coal scams No:I4.IV4 and V2,were formed in different accumulationg enviromcnts and is located to Yuxtan coal district, Hcnan, have been taken b> the auther. The rsuit shows that the range of the sulphur content of the coal Seam formed in salt water is>3%,in cxist as straw berry pynite.The sulphur content of the coal Seam formed in salt water is<0.6% and this sulphur mainly exists as crgan sulphur. As content is coals is bound up with coal一accumulation cwiroment and disturbing degree of swamp water.The coal seams formed in the cabonatous shore with clear water and sight disturbance usually contain clow ash content.The coal scams developed In the scawardarea of abandoned delta with the dlsturbing water and detrital supplement frequently contain the relative high ash content; and in the landward area of abandoned delta, the relative low ash content. The ash component in coal reflects the character of swamp water. With increasing the water salinty in swamp, ash component specific value(K=(SiO2+Al203)/(Fe2O3+Ca0+Mg0+SO3))gradually dc- creases. The coal seams formed in fresh water swamp, K=10-3.5; in salt water swamp, K<3.5- In same coal seam the change of sulphur content is responsible for the depth of water in swamp. The depth was mainly controlled by the ancient topographical feat ures which were efTected by the thickness of underlying sandstone. Where the underlying sandstone is relative thick, the defferent compact is smaller, generally formed higher landforms, therefor the coal seams formed under the shallow water usully contain lower sulphur. These character is opposite from the places where under lying sandstone thickness is small. The higher landform in swamp catches the deposits carried by wind casyly，then the coal scams contain higer ash content. Whether depositional enviromcnt of coal roof will effect the sulphur content and sulphur type in underlying coal scams is determined by the lasting tirvc of the environment of coal roof. The longer the lasting time, the more marked efTect. Combining the change features of sulphur and ash contents with the study of depositional and coal-acumulating enviroments, it is posible to forecast, explore and exploit the coal with lower sulphur and ash contents in where coal seams is consided containing high sulphur and ash contents.
In order to forecast, explore and cxplmt relative high quality coals,it is necessary to understand the law of sulphur and ash contents and the factor controlline the chanemg law.For this reason the study on the coal qualUy of coal scams No:I4.IV4 and V2,were formed in different accumulationg enviromcnts and is located to Yuxtan coal district, Hcnan, have been taken b> the auther. The rsuit shows that the range of the sulphur content of the coal Seam formed in salt water is>3%,in cxist as straw berry pynite.The sulphur content of the coal Seam formed in salt water is<0.6% and this sulphur mainly exists as crgan sulphur. As content is coals is bound up with coal一accumulation cwiroment and disturbing degree of swamp water.The coal seams formed in the cabonatous shore with clear water and sight disturbance usually contain clow ash content.The coal scams developed In the scawardarea of abandoned delta with the dlsturbing water and detrital supplement frequently contain the relative high ash content; and in the landward area of abandoned delta, the relative low ash content. The ash component in coal reflects the character of swamp water. With increasing the water salinty in swamp, ash component specific value(K=(SiO2+Al203)/(Fe2O3+Ca0+Mg0+SO3))gradually dc- creases. The coal seams formed in fresh water swamp, K=10-3.5; in salt water swamp, K<3.5- In same coal seam the change of sulphur content is responsible for the depth of water in swamp. The depth was mainly controlled by the ancient topographical feat ures which were efTected by the thickness of underlying sandstone. Where the underlying sandstone is relative thick, the defferent compact is smaller, generally formed higher landforms, therefor the coal seams formed under the shallow water usully contain lower sulphur. These character is opposite from the places where under lying sandstone thickness is small. The higher landform in swamp catches the deposits carried by wind casyly，then the coal scams contain higer ash content. Whether depositional enviromcnt of coal roof will effect the sulphur content and sulphur type in underlying coal scams is determined by the lasting tirvc of the environment of coal roof. The longer the lasting time, the more marked efTect. Combining the change features of sulphur and ash contents with the study of depositional and coal-acumulating enviroments, it is posible to forecast, explore and exploit the coal with lower sulphur and ash contents in where coal seams is consided containing high sulphur and ash contents.
1989, 7(3): 105-111.
Abstract:
The thickness of Jiouzhoutai loess section of Lanzhou is 318.2m which is the thickest loess section in China and in the world.The upsand loss and low-sand loess marker beds are respectively at 103.5 to 127.0meters and at 45.0 to 52.5 meters high, which shows that the loess section was formed at 1.35 Ma ago and aeolian-loess began to deposit at about 140 Ma ago.The B/M boundary and Jaramiuo normal event are located at 135.0m and at 75.5-92.Om high, which means that the loess scetion should be formed at 1.30 Ma. Also there are thirty-four palaeosols among which the first eight layers of palaeosols are so called the first Wucheng palaeosol.group formed at 1.48 Ma So the profile was formed at 1.40-150 Ma.The fission tract age of gypsum samples collected at profile bottom and at S.Om high are respectively at 1.48Ma and 1.45 Ma. Therefore. the caolianloess of Jiouzhoutai loess profile began to deposit at about 1.30 Ma and Alluvial-loess began to deposit at about 1.40-1.50 Ma.
The thickness of Jiouzhoutai loess section of Lanzhou is 318.2m which is the thickest loess section in China and in the world.The upsand loss and low-sand loess marker beds are respectively at 103.5 to 127.0meters and at 45.0 to 52.5 meters high, which shows that the loess section was formed at 1.35 Ma ago and aeolian-loess began to deposit at about 140 Ma ago.The B/M boundary and Jaramiuo normal event are located at 135.0m and at 75.5-92.Om high, which means that the loess scetion should be formed at 1.30 Ma. Also there are thirty-four palaeosols among which the first eight layers of palaeosols are so called the first Wucheng palaeosol.group formed at 1.48 Ma So the profile was formed at 1.40-150 Ma.The fission tract age of gypsum samples collected at profile bottom and at S.Om high are respectively at 1.48Ma and 1.45 Ma. Therefore. the caolianloess of Jiouzhoutai loess profile began to deposit at about 1.30 Ma and Alluvial-loess began to deposit at about 1.40-1.50 Ma.
1989, 7(3): 121-128.
Abstract:
It is well know that clay minerals such as montmorillonite or interstratified montmorillonite strongly absorb dissolved uranyl species. 'This paper presents that halloysite could also absorb more uranium and is main uraniferous mineral in some economic uranium deposits. By use of electron microscope. X-ray ditTraction，and infrared spectroscopy, characteristics of uraniferous halloysite is described and recogsized. The results showed that the structural layers of halloysite were changed because of the penetrating and uptaking of uranyl species. The conclusion is that uranly species not only be absorbed by the surface of halloysite but penetrated into structrual layers of halloysite.Under the different geological conditions, The various clay minerals with high .uranium could be formed: montmorillonite or interstratified montmorillonite formed in the alkaline environment, while halloysite formed in the neutro-acid environment.
It is well know that clay minerals such as montmorillonite or interstratified montmorillonite strongly absorb dissolved uranyl species. 'This paper presents that halloysite could also absorb more uranium and is main uraniferous mineral in some economic uranium deposits. By use of electron microscope. X-ray ditTraction，and infrared spectroscopy, characteristics of uraniferous halloysite is described and recogsized. The results showed that the structural layers of halloysite were changed because of the penetrating and uptaking of uranyl species. The conclusion is that uranly species not only be absorbed by the surface of halloysite but penetrated into structrual layers of halloysite.Under the different geological conditions, The various clay minerals with high .uranium could be formed: montmorillonite or interstratified montmorillonite formed in the alkaline environment, while halloysite formed in the neutro-acid environment.
1989, 7(3): 21-30.
Abstract:
Qinzhou Basin is located in Guangxi Province, South China, extending in NE-SW direction,200km long and 50-70km widc.Its southwest part passes through the Tonkin Gulf then ended in Vitnam.It is bounded on the east and west by two deep faults. This basin had had a continuous history from Silurianor earlier J to Permian during which the Silurian-Middle Devonian ilyschoid formation and Upper Devonian-Lower Permian siliceous-muddy formation formed.The basin is a particuliar tectonic unit in South China because of no uncomformity between the Silurian and Devonian Systcm.Its teesonic feature is very different from adjacent rrgions’in tithcr geological history or rock formation. The Silurian-Middle Devonian flyschoid formation here, about 9500m thick, is composed of sandstone, siltstone and mudstone of which make up rhythmic succcsions with thickness of about SOcm per unit.Conglomcrate can only be seen on sonic part of the bottom of the Silurian.Many kinds of fossil such as graptolite, tentaculitid and trilobite contained. most of them arc planktonic (few nectonic) and cosmopolitan taza.Inferably, scawater circulation and animal exchange;neat between this basin and outer oceans may have taken place during that period Onthc studies of field occurcncc, sedimentary structure and texture, and grmn一sift anallyscs ace., it is proposed the origin and tec:onic setting of the formation.It has a that h:ghcr malurl;y of borher;,incral and texture than typical turbidite. The average sandstone/m udstunc value(in thicknca) is about 2.Framcwork minerals are chiefly quartzcs.Thcre arc graded bcddings, lead srueture and cther charactcristics of turbidite on one hand, and little crossbcddings,flow marks,imbricated texture of mineral grains or faecle pellets,and other diagnostics of traction flow dcposis on the olhcr hand. Sedimentary structure and grain-size analyses show a transitional feature betwecn turbidcte and flvial (nr tractne cur-rent) deposit, only possibly the latter rcprescnecd a s mariac river一一a contour currcnt.lt Is important that there arc a kind of very L'1in (0.5 - cm) mudstunc。fairly sorted sandstone) lntcrclatcd into much thicker sandstone(or mudstonc).Such rocks arc very much liketos the muddy contourite(or sandstone) described by Stow&Lovc&Lovell (1979) Especially，the presence of pirnodal directions c.g.downslopc and alongslopc at about 90` is a key indreater in determintion of conearite. Furthermore, the sandstone here are chichy graywacke, most of tnem are quarly一nch，type one.and very similar to those of passive cononantal margin type sandstone in prochercal The featre of the contouritc can also be contrasted with those in the word. Summing up the above mcntiomd, it is concluded that the Silurion-Middle Devosion fiyschoid formation of the Qinzhoa Basin is a low dcnsy turbidce which obvioncy were rewerked or vuperimposed by paleocontcur current.Thcy formed on a continenyisl rise rechting the tectone setuag of the tectonie setuag of the ,Atlantic type of cast continental margin.
Qinzhou Basin is located in Guangxi Province, South China, extending in NE-SW direction,200km long and 50-70km widc.Its southwest part passes through the Tonkin Gulf then ended in Vitnam.It is bounded on the east and west by two deep faults. This basin had had a continuous history from Silurianor earlier J to Permian during which the Silurian-Middle Devonian ilyschoid formation and Upper Devonian-Lower Permian siliceous-muddy formation formed.The basin is a particuliar tectonic unit in South China because of no uncomformity between the Silurian and Devonian Systcm.Its teesonic feature is very different from adjacent rrgions’in tithcr geological history or rock formation. The Silurian-Middle Devonian flyschoid formation here, about 9500m thick, is composed of sandstone, siltstone and mudstone of which make up rhythmic succcsions with thickness of about SOcm per unit.Conglomcrate can only be seen on sonic part of the bottom of the Silurian.Many kinds of fossil such as graptolite, tentaculitid and trilobite contained. most of them arc planktonic (few nectonic) and cosmopolitan taza.Inferably, scawater circulation and animal exchange;neat between this basin and outer oceans may have taken place during that period Onthc studies of field occurcncc, sedimentary structure and texture, and grmn一sift anallyscs ace., it is proposed the origin and tec:onic setting of the formation.It has a that h:ghcr malurl;y of borher;,incral and texture than typical turbidite. The average sandstone/m udstunc value(in thicknca) is about 2.Framcwork minerals are chiefly quartzcs.Thcre arc graded bcddings, lead srueture and cther charactcristics of turbidite on one hand, and little crossbcddings,flow marks,imbricated texture of mineral grains or faecle pellets,and other diagnostics of traction flow dcposis on the olhcr hand. Sedimentary structure and grain-size analyses show a transitional feature betwecn turbidcte and flvial (nr tractne cur-rent) deposit, only possibly the latter rcprescnecd a s mariac river一一a contour currcnt.lt Is important that there arc a kind of very L'1in (0.5 - cm) mudstunc。fairly sorted sandstone) lntcrclatcd into much thicker sandstone(or mudstonc).Such rocks arc very much liketos the muddy contourite(or sandstone) described by Stow&Lovc&Lovell (1979) Especially，the presence of pirnodal directions c.g.downslopc and alongslopc at about 90` is a key indreater in determintion of conearite. Furthermore, the sandstone here are chichy graywacke, most of tnem are quarly一nch，type one.and very similar to those of passive cononantal margin type sandstone in prochercal The featre of the contouritc can also be contrasted with those in the word. Summing up the above mcntiomd, it is concluded that the Silurion-Middle Devosion fiyschoid formation of the Qinzhoa Basin is a low dcnsy turbidce which obvioncy were rewerked or vuperimposed by paleocontcur current.Thcy formed on a continenyisl rise rechting the tectone setuag of the tectonie setuag of the ,Atlantic type of cast continental margin.
1989, 7(3): 53-62.
Abstract:
The sedimentary environments of Early- Middle Carboniferous period in the northwest region of Tarim Basin, the sequence is(From bottom to top) river, shore to shallow sea environments. Late Carboniferous period in the district stepped to a model near shore carbonate flat. The author is the first one who studied the diagenesis of Carboniferous sandstone in the northwest region of the Tarim Basin. Based on the microxopic analysis, cathodoluminesceae. SEM, X-diffraction oxygen and carbon isotopes are adopted on the research of major aspects of diagenesis such as compaction. presolution. cementation. In addition, nemorous approaches on features, content, sequence and environment of forming and their impacts on the pores in sandstone have been made to the aspects of siliceous dioxide, carbonate minerals and caly minerals cement which were drawn from the sandstone of the Carboniferous. Depend on the analysis results of reflectance of vitrinite (Ro)，spore-pollen colour and illite opening index, it is deduced that the bight diagenetic temperature of the sandstone. The purpose of this paper is to determine the diagenetic stage of the sandstone and to analyze its diagenetic history and the charateristic of pore evolution. Through research. the following main conclusions are proposed in the present paper: 1 .Carbonifbrous is in the middle-late postdiagenetic stage, have undergone deep compaction and presolution, quartz overgrowth is wide-spread, illite bas high crystallinity, ferrocalcite, dolomite and ferrodolomite often appear sandstone cements. Diagenetic temperature is 120D to 2001r. 2. During the long term diagenesis. the primary pores of Carboniferous sandstone nearly disappeared because of compaction. presolution. cementation of silica. self-precipitation and recrystallization of clay minerals. replacement of carbonate; the most effective in fluence factor of proposity is the cementation of silica represented by quartz overgrowth. which filled up more than 50 percent of residual pruaary pores. 3. During the postdiagenetic stage few secondary pores can be formed in siliceous cemented sandstone, so it can not be a valuable reservoir. But for calcareous cemented sandstone. under the reaction of acidic pore water with soluble components such as carbonate minerals. some secondary pores can be formed. promoted the quality of servoir bed.
The sedimentary environments of Early- Middle Carboniferous period in the northwest region of Tarim Basin, the sequence is(From bottom to top) river, shore to shallow sea environments. Late Carboniferous period in the district stepped to a model near shore carbonate flat. The author is the first one who studied the diagenesis of Carboniferous sandstone in the northwest region of the Tarim Basin. Based on the microxopic analysis, cathodoluminesceae. SEM, X-diffraction oxygen and carbon isotopes are adopted on the research of major aspects of diagenesis such as compaction. presolution. cementation. In addition, nemorous approaches on features, content, sequence and environment of forming and their impacts on the pores in sandstone have been made to the aspects of siliceous dioxide, carbonate minerals and caly minerals cement which were drawn from the sandstone of the Carboniferous. Depend on the analysis results of reflectance of vitrinite (Ro)，spore-pollen colour and illite opening index, it is deduced that the bight diagenetic temperature of the sandstone. The purpose of this paper is to determine the diagenetic stage of the sandstone and to analyze its diagenetic history and the charateristic of pore evolution. Through research. the following main conclusions are proposed in the present paper: 1 .Carbonifbrous is in the middle-late postdiagenetic stage, have undergone deep compaction and presolution, quartz overgrowth is wide-spread, illite bas high crystallinity, ferrocalcite, dolomite and ferrodolomite often appear sandstone cements. Diagenetic temperature is 120D to 2001r. 2. During the long term diagenesis. the primary pores of Carboniferous sandstone nearly disappeared because of compaction. presolution. cementation of silica. self-precipitation and recrystallization of clay minerals. replacement of carbonate; the most effective in fluence factor of proposity is the cementation of silica represented by quartz overgrowth. which filled up more than 50 percent of residual pruaary pores. 3. During the postdiagenetic stage few secondary pores can be formed in siliceous cemented sandstone, so it can not be a valuable reservoir. But for calcareous cemented sandstone. under the reaction of acidic pore water with soluble components such as carbonate minerals. some secondary pores can be formed. promoted the quality of servoir bed.
1989, 7(3): 73-81.
Abstract:
The Tengchong Basin, located in the Western Yunnan, China, is a long and narrow intermountainous basin and about 35kmZin area.The mikkle and laid Pleistocene coal (peat)一bearing strata, made up of two terrigenous sedimentary cycles interbeding extructive rocks, was deposited on the Cretaceous granite base of the basin. Peat of soft brown coal seams occur in the upper section of each cycle. The soft brown coal in the lower cycle was formed about 600, 000 B. P. and the peat in the upper about 75, 000 to 100, 000 B.P., part of which had also been transformed into soft brown coal.Tengchong region lies in the intermediatary zone between Euroasia plate and Indian plate, in which there exsit the remarkable phenomena of geothermal anomaly, the violent and frequet volcanic activities and the frequent tectonic movements of earthquacks during the Quaternary.These poarticular geloogical processes led to the anomalous coaliCication transforming the Quaternary peat into soft brown coal in Tengchong Basin. The evidences in both coal petrology and organic geochemistry show that, in the process of the early coalification in the basin，the physical characteristics and the chemical composition and structure of the organic matter evolvod in certain regularity.With the burial depth increasing and toward the central part of the basin, the compacted degree of peat or brown coal is strengthened; the random reflectance Rr°of euulminites become increasing, ranging from 0.12% of the samples near the groundsurface to 0.33% of those at the depth of about 170 meters; the wavelength .λmax at the maximum intensity of the tluorescent spectrum under ultraviolet一ligt irradition gradually shifts to the longer wavelengrh, and it should be es pecially noted that there is a distinct turning point between 0. 16% Rr°and 0.22% Rr°，near which the evolving direction of the red/green quotation Q of sporinites changes from decending tendency to astending one with the Rr° iacreasing.As the Rr° of euulrninites rises, there are the increasing tendencies in the calorific value/vumicacid matter ratio, the aromaticity, the fulvic acid/humicacid ratio, the temperature Tmax the maximum rate of generation of trotting compounds, the ratio CH4/nC2-4and the yield of binocycloaromatic hydrocarbon in cracking compounds and the ratio of aromatic hydrocarbon to heteroaromatic compounds in free compounds, the optical densities E750, E800, E1600and E1375/E2920ratio, and the concentration Ng of the free radicals in the organic matter, but there exist also the decreasing tendency in the H/C atomic ratio, the S,implying the yield of free hydrocarbon and the Szshowing that of cracking compounds, the yield of monocycloarmatic hyerocarvbon and the carbon pre ference index CPI of n一alkane in cracking hydrocarbon as well as E1375, E720, E1465, E2890and E1265, Additionally the absorbed peaks with wave numter 1500-15110cm>in FTIR spectra change from marking to almost disapperring with the Rr rising, and the latter is the typical characteristic of brown coal. It should be yet pointed out that there is a varying rate of evoluation in both geochemical and pitysica: properties.In the burial peat with R°less than 0.16-0.18%and Tmax less than of equal to 400℃，the various geochernical properties developed very slowly and dispersed much.In the soft brown coal with R°morc than.0.22%or so and Tmaxmore than or equal to 410，they developed at a relatively greater rate and the dispersion became little. These characteristics display that there are still the distinct substages even in the brief early gcochemical coalification from peat to soft brown coal in Tengchong Basin.Basing on these,the authors divide the stage of the early coalitication of the basin into three substages, i.c., those of soft peat, hard peat and Tmax，arc used as the principal pa:amcters and the fluorescen: parameters Q and A243which arc wonhy to be nurthcr studied, are used as the suppicmcntary those.In addiuon，tthere are also the rcmarkabie differences m the macruscopom physteal properucs amongst the sabstagcp. Through comparing with the Quat nary peat prolilc m Drama Basin. Greece, and the Phccene sost brown coal proflc in Zhcnaa Basin, the Western Yunnan, China, the authors gencralmc the anomaluous characteristics of the early coalification in Tcngchong Basin: 1) the substagc of soft pent.that of normal biogeochcmical coalification, in which there is almost no difference between Tcngchunb Basin and Drama Basin; 2) in the substagc of hard peat, there arc stronger dccompusition, synthctization一condensation polymerization, gclir cation and compaction in Tengchong Basin than to Drama Basin; 3) in the substagc of soft brown coal, there arc the greater rate and the hiahcr dcgrcv o: coalification山Tcngchong Basin than in Zhcnan Bastn.Thus, it can be known that the rate and lhc degree of the early coalification in Tengchong Basin arc much greater than those to the normal casts and the I'au.at there wasa nomalous coalification in Tengchong Basin has been undoubted. The cross places of both NE and N'JV trend faults in the base, naer which the local hight empefra;urc"anomaly occurred, made up the passageways through which the powerful geothermal 11uw、 with the highest degree of coalificauon to the asin tics just in such an anomalous place.Therc exit som; vocauie constituents such as CO2, F, B and S m the groundu titer in the basin、so it could be dedacel teat the heat given off by the shallow magma bodies be ever the powerful heat of the paiacogeothcrmal field.The anomalous coahncation might be also innmatcly assuctatcd with the and wolcnt actiwnes of earthquakes occurred within and around the basin since the late Pleistocene. 0a the one hand, the impoact wave caused ty the carthauacks frequently compressed the peat or brown coal scams so that the seams occured at the lesser depth display the compacted degree that cou;d be reached lust at the greater depth in the normal cases, and on the other hand, it might also accelerate the coa;tlicatiu, only under the palacogcothermal temperature much lower than that which would be just needed to the normal coalificatiln.Thcrrefore, the authors suggest the concept“anomalous coahlication"，which ineludes the following two aspects: 1) t!ic anomalous rate and degree of coali:ication; 2) the anomaloJs factors of coalilication. So far as Tengchong Basin goes, the factors arc the anomaluosly powerful paiaco-geothermal flows and the violent and frequent tcctomc movements derived from carthquakcs.
The Tengchong Basin, located in the Western Yunnan, China, is a long and narrow intermountainous basin and about 35kmZin area.The mikkle and laid Pleistocene coal (peat)一bearing strata, made up of two terrigenous sedimentary cycles interbeding extructive rocks, was deposited on the Cretaceous granite base of the basin. Peat of soft brown coal seams occur in the upper section of each cycle. The soft brown coal in the lower cycle was formed about 600, 000 B. P. and the peat in the upper about 75, 000 to 100, 000 B.P., part of which had also been transformed into soft brown coal.Tengchong region lies in the intermediatary zone between Euroasia plate and Indian plate, in which there exsit the remarkable phenomena of geothermal anomaly, the violent and frequet volcanic activities and the frequent tectonic movements of earthquacks during the Quaternary.These poarticular geloogical processes led to the anomalous coaliCication transforming the Quaternary peat into soft brown coal in Tengchong Basin. The evidences in both coal petrology and organic geochemistry show that, in the process of the early coalification in the basin，the physical characteristics and the chemical composition and structure of the organic matter evolvod in certain regularity.With the burial depth increasing and toward the central part of the basin, the compacted degree of peat or brown coal is strengthened; the random reflectance Rr°of euulminites become increasing, ranging from 0.12% of the samples near the groundsurface to 0.33% of those at the depth of about 170 meters; the wavelength .λmax at the maximum intensity of the tluorescent spectrum under ultraviolet一ligt irradition gradually shifts to the longer wavelengrh, and it should be es pecially noted that there is a distinct turning point between 0. 16% Rr°and 0.22% Rr°，near which the evolving direction of the red/green quotation Q of sporinites changes from decending tendency to astending one with the Rr° iacreasing.As the Rr° of euulrninites rises, there are the increasing tendencies in the calorific value/vumicacid matter ratio, the aromaticity, the fulvic acid/humicacid ratio, the temperature Tmax the maximum rate of generation of trotting compounds, the ratio CH4/nC2-4and the yield of binocycloaromatic hydrocarbon in cracking compounds and the ratio of aromatic hydrocarbon to heteroaromatic compounds in free compounds, the optical densities E750, E800, E1600and E1375/E2920ratio, and the concentration Ng of the free radicals in the organic matter, but there exist also the decreasing tendency in the H/C atomic ratio, the S,implying the yield of free hydrocarbon and the Szshowing that of cracking compounds, the yield of monocycloarmatic hyerocarvbon and the carbon pre ference index CPI of n一alkane in cracking hydrocarbon as well as E1375, E720, E1465, E2890and E1265, Additionally the absorbed peaks with wave numter 1500-15110cm>in FTIR spectra change from marking to almost disapperring with the Rr rising, and the latter is the typical characteristic of brown coal. It should be yet pointed out that there is a varying rate of evoluation in both geochemical and pitysica: properties.In the burial peat with R°less than 0.16-0.18%and Tmax less than of equal to 400℃，the various geochernical properties developed very slowly and dispersed much.In the soft brown coal with R°morc than.0.22%or so and Tmaxmore than or equal to 410，they developed at a relatively greater rate and the dispersion became little. These characteristics display that there are still the distinct substages even in the brief early gcochemical coalification from peat to soft brown coal in Tengchong Basin.Basing on these,the authors divide the stage of the early coalitication of the basin into three substages, i.c., those of soft peat, hard peat and Tmax，arc used as the principal pa:amcters and the fluorescen: parameters Q and A243which arc wonhy to be nurthcr studied, are used as the suppicmcntary those.In addiuon，tthere are also the rcmarkabie differences m the macruscopom physteal properucs amongst the sabstagcp. Through comparing with the Quat nary peat prolilc m Drama Basin. Greece, and the Phccene sost brown coal proflc in Zhcnaa Basin, the Western Yunnan, China, the authors gencralmc the anomaluous characteristics of the early coalification in Tcngchong Basin: 1) the substagc of soft pent.that of normal biogeochcmical coalification, in which there is almost no difference between Tcngchunb Basin and Drama Basin; 2) in the substagc of hard peat, there arc stronger dccompusition, synthctization一condensation polymerization, gclir cation and compaction in Tengchong Basin than to Drama Basin; 3) in the substagc of soft brown coal, there arc the greater rate and the hiahcr dcgrcv o: coalification山Tcngchong Basin than in Zhcnan Bastn.Thus, it can be known that the rate and lhc degree of the early coalification in Tengchong Basin arc much greater than those to the normal casts and the I'au.at there wasa nomalous coalification in Tengchong Basin has been undoubted. The cross places of both NE and N'JV trend faults in the base, naer which the local hight empefra;urc"anomaly occurred, made up the passageways through which the powerful geothermal 11uw、 with the highest degree of coalificauon to the asin tics just in such an anomalous place.Therc exit som; vocauie constituents such as CO2, F, B and S m the groundu titer in the basin、so it could be dedacel teat the heat given off by the shallow magma bodies be ever the powerful heat of the paiacogeothcrmal field.The anomalous coahncation might be also innmatcly assuctatcd with the and wolcnt actiwnes of earthquakes occurred within and around the basin since the late Pleistocene. 0a the one hand, the impoact wave caused ty the carthauacks frequently compressed the peat or brown coal scams so that the seams occured at the lesser depth display the compacted degree that cou;d be reached lust at the greater depth in the normal cases, and on the other hand, it might also accelerate the coa;tlicatiu, only under the palacogcothermal temperature much lower than that which would be just needed to the normal coalificatiln.Thcrrefore, the authors suggest the concept“anomalous coahlication"，which ineludes the following two aspects: 1) t!ic anomalous rate and degree of coali:ication; 2) the anomaloJs factors of coalilication. So far as Tengchong Basin goes, the factors arc the anomaluosly powerful paiaco-geothermal flows and the violent and frequent tcctomc movements derived from carthquakcs.
1989, 7(3): 91-92.
Abstract:
Occupied by "biological configuration' steranes first, then down to a certain depth, the relative richness of "geological configuration' increases obviously, its C29ааа一20S/ааа一(20S+20R) and авв- (20R+20S)-C29/∑C29will be as high as 24.6-47.7% and 23,0-51.1。respectively. But beyond a cerlain depth, again the "biological configuration' steranes occupy the absolute majority. It causes the "geo- logical configuration' steranes showing the distribution feature of "from low to high to low’in whole immatured source rocks. It is more interesting that above mentioned distribution feature has an obvious change law in various sections which could not be explained by "reworking': (1) The depth where high "geological configuration" steranes appeared is closely related with the geological age. The older the age is，the shallower the maturity threshold is and the later the high value appears cnamely, much shallower buried depth;in the other hand, the younger the age is，the deeper the maturity threshold is and the later the high value appears correspondingly (namely, much deeper buried depth.For instance, in Erlian Basin, the maturity threshold of the Bazhong group (K1b2) and the Bashang group K1b3 in Mesozoic is 1500m and 1800m, respectively, their high value appears in 285-530m and 635-1260m, respectively; while the maturity threshold is in the range of 2500-3100m For several sedimentary sections 1n the Palaeogene Shahcjie group 3 Formation (Es3) of the Bohai Bay Basin the high value appears laterly m 1215-1908m. as for Neogene (N2) of Qinghai Qaidam Basin with maturity threshold of 3300m, the high value appears much laterly about 2600m. (2) The low value after the high value of "geological configuration' steranes always corresponds to signiricant deoxidation of kerogen. That is，the high value always appears baCore significant deoxidation of kerogen. Once kerogen enters the significant dcoxidation period, the relative richness of“geological configuration" sterane is obviously decreased correspondingly, then causing another low ratio region appears between C29ааа一20S/ааа一(20S+20R) and авв- (20R+20S)-C29/∑C29.
Occupied by "biological configuration' steranes first, then down to a certain depth, the relative richness of "geological configuration' increases obviously, its C29ааа一20S/ааа一(20S+20R) and авв- (20R+20S)-C29/∑C29will be as high as 24.6-47.7% and 23,0-51.1。respectively. But beyond a cerlain depth, again the "biological configuration' steranes occupy the absolute majority. It causes the "geo- logical configuration' steranes showing the distribution feature of "from low to high to low’in whole immatured source rocks. It is more interesting that above mentioned distribution feature has an obvious change law in various sections which could not be explained by "reworking': (1) The depth where high "geological configuration" steranes appeared is closely related with the geological age. The older the age is，the shallower the maturity threshold is and the later the high value appears cnamely, much shallower buried depth;in the other hand, the younger the age is，the deeper the maturity threshold is and the later the high value appears correspondingly (namely, much deeper buried depth.For instance, in Erlian Basin, the maturity threshold of the Bazhong group (K1b2) and the Bashang group K1b3 in Mesozoic is 1500m and 1800m, respectively, their high value appears in 285-530m and 635-1260m, respectively; while the maturity threshold is in the range of 2500-3100m For several sedimentary sections 1n the Palaeogene Shahcjie group 3 Formation (Es3) of the Bohai Bay Basin the high value appears laterly m 1215-1908m. as for Neogene (N2) of Qinghai Qaidam Basin with maturity threshold of 3300m, the high value appears much laterly about 2600m. (2) The low value after the high value of "geological configuration' steranes always corresponds to signiricant deoxidation of kerogen. That is，the high value always appears baCore significant deoxidation of kerogen. Once kerogen enters the significant dcoxidation period, the relative richness of“geological configuration" sterane is obviously decreased correspondingly, then causing another low ratio region appears between C29ааа一20S/ааа一(20S+20R) and авв- (20R+20S)-C29/∑C29.
1989, 7(3): 113-120.
Abstract:
This paper deals with the red soil of Neogene based on the data collected by field survey, chemical test and microtezture. The red soil is red and homogeneous in grain size, but it is not of stratil3cation and grains larger than sand generally. The black-brown clay film and calcareous conccretion or conccretion layers can be seen often in the red soil. According to the characteristics of the red soil being of homogeneous grain size and not being of stratification, the origin of the red soil difTers from that of normal aqueous deposit. Through miscroscopc observation, we found a considerable amount of optically oriented clay film that mainly occurs as Mowing colloid in cracks. According to the studing results in pedology. optically oriented clay film is formed by soil-forming process and，if it developed well，is the characteristic of the soils of forest more intensely leached. Consequently it can be determined that the red soil is a kind of paleosoil that underwent morestrong soil和rmation. The part of the red soil rich in black-brown clay film and optically oriented clay film is a clay horizon of the soil and the calcareous concretion layer beneath the clay horizon is a illuvial horizon. Because the development of soil is in surficial condition. the author inter that the red soil under study is mainly formed in subaerial environment and is of eolian origin. In the light of the developed degree of the optically oriented clay film and the illuvium. It is considered that there were both the forest and the forest-steppe during the formation. the CaCOlcontent is 3-S% generally and the CaCOjoccurs in the form of elastic grains or cementing material in the deposit of river-lacustrine facics. Though the CaCO3takes much amount(10- 20)in the loess，the CaC03content in recent windblown dust is only 3%.Hence a part of the CaCO3jia Quaternary loess was formed after the loess was deposited. The CaCO3content in the red soil of Ncogene is much more than that in the loess in Xian suburs. Why does the CaCO3occur in the form of concretion or concretion layers? These are the problems puzzled people. In the northwest China and the Hubci plain, the CaCO3takes 20% or so in recent soil，which indicates that a good deal of CaCO3can be produi in soil- forming process. There is a lot of calcareous concretion or concretion layer beneath the palcosol in the loess，whick demonstrates that soil-forming process is very favourable to producing calcareous concretion or concretion layers. For this reason, it can be deduced that besides a part of CaCO3transported by wind considerable and even most part of CaCO3was produced after the red soil deposited. Biology, rainwater and minerals weathered to release calcium resulted in CaCO3produced and concentrated. The deduction is consistent with the optically brentied clay film found in the red soil. By chemicial examination of the soil，it is known that SiO2s prominent, about 60%.Al203the second，generally 15-16% or so, and thenFe2O3, 6-7%.The chemical composition of the red soil is stmt lar to that of the loess，but there is a little defference in Al203that is more amount in the red soil than in the loess. The reason of why the contents of Al203and Fe2O3have more amount in the red soil than in the loess is that the accumulation of A12O3Fe203removing much slowly weathering and soil- forming process. In the granulometric composition of the red soil, the grains from O.OS to O.OOSmm take 40一4S% in most of the samples. the grade more than O.OSmmis about 20%，and finer than O.OSmm takes 35-SO% in most samples. There is the similarity between the red soil and the loess in the grain size, but the fine grains obviously relaled to clayization in soil-forming process are more in the red soil than in the loess. Although 0. OS- 0. OOSmm grains of the loess are over 50%，this grade size is changeable in component. It can be changed into very fine grains under warm and moist climate to bring about a dorm. nant grade size less山as O.OSmm instead of 0.05-O.OOSmm. By present observation and measurement. the suspended grains transported by wind are the ones less than 0.2mm, which is unchangeable character- istic of windblown dust.Consequently the grains less than O.OSmm is dominant, does not contain grains less than O.OSmm is dominant, does not contain grains larger than 0.2mm generally and is of extreme sorting. By miscroscope observation. It was known that the red soil does not contain grains larger than 0.2mm. According to mentioned above, the red soil is of the outstanding characteristics of winddrift dust. it should be eolian deposit. Most geologists hold that loess .which was deposited in 2.4Ma ago and in cold-dry climate，is a sort of mark that a great deal of the eoliaa deposit of Cainozoic era began to deposite，but on the basis of the study in this paper, as early as before the loess began to deposit，a vast amount of deposit existed, There were possibly two kinds of form of climate that is as follows during the formation of the red soil.
This paper deals with the red soil of Neogene based on the data collected by field survey, chemical test and microtezture. The red soil is red and homogeneous in grain size, but it is not of stratil3cation and grains larger than sand generally. The black-brown clay film and calcareous conccretion or conccretion layers can be seen often in the red soil. According to the characteristics of the red soil being of homogeneous grain size and not being of stratification, the origin of the red soil difTers from that of normal aqueous deposit. Through miscroscopc observation, we found a considerable amount of optically oriented clay film that mainly occurs as Mowing colloid in cracks. According to the studing results in pedology. optically oriented clay film is formed by soil-forming process and，if it developed well，is the characteristic of the soils of forest more intensely leached. Consequently it can be determined that the red soil is a kind of paleosoil that underwent morestrong soil和rmation. The part of the red soil rich in black-brown clay film and optically oriented clay film is a clay horizon of the soil and the calcareous concretion layer beneath the clay horizon is a illuvial horizon. Because the development of soil is in surficial condition. the author inter that the red soil under study is mainly formed in subaerial environment and is of eolian origin. In the light of the developed degree of the optically oriented clay film and the illuvium. It is considered that there were both the forest and the forest-steppe during the formation. the CaCOlcontent is 3-S% generally and the CaCOjoccurs in the form of elastic grains or cementing material in the deposit of river-lacustrine facics. Though the CaCO3takes much amount(10- 20)in the loess，the CaC03content in recent windblown dust is only 3%.Hence a part of the CaCO3jia Quaternary loess was formed after the loess was deposited. The CaCO3content in the red soil of Ncogene is much more than that in the loess in Xian suburs. Why does the CaCO3occur in the form of concretion or concretion layers? These are the problems puzzled people. In the northwest China and the Hubci plain, the CaCO3takes 20% or so in recent soil，which indicates that a good deal of CaCO3can be produi in soil- forming process. There is a lot of calcareous concretion or concretion layer beneath the palcosol in the loess，whick demonstrates that soil-forming process is very favourable to producing calcareous concretion or concretion layers. For this reason, it can be deduced that besides a part of CaCO3transported by wind considerable and even most part of CaCO3was produced after the red soil deposited. Biology, rainwater and minerals weathered to release calcium resulted in CaCO3produced and concentrated. The deduction is consistent with the optically brentied clay film found in the red soil. By chemicial examination of the soil，it is known that SiO2s prominent, about 60%.Al203the second，generally 15-16% or so, and thenFe2O3, 6-7%.The chemical composition of the red soil is stmt lar to that of the loess，but there is a little defference in Al203that is more amount in the red soil than in the loess. The reason of why the contents of Al203and Fe2O3have more amount in the red soil than in the loess is that the accumulation of A12O3Fe203removing much slowly weathering and soil- forming process. In the granulometric composition of the red soil, the grains from O.OS to O.OOSmm take 40一4S% in most of the samples. the grade more than O.OSmmis about 20%，and finer than O.OSmm takes 35-SO% in most samples. There is the similarity between the red soil and the loess in the grain size, but the fine grains obviously relaled to clayization in soil-forming process are more in the red soil than in the loess. Although 0. OS- 0. OOSmm grains of the loess are over 50%，this grade size is changeable in component. It can be changed into very fine grains under warm and moist climate to bring about a dorm. nant grade size less山as O.OSmm instead of 0.05-O.OOSmm. By present observation and measurement. the suspended grains transported by wind are the ones less than 0.2mm, which is unchangeable character- istic of windblown dust.Consequently the grains less than O.OSmm is dominant, does not contain grains less than O.OSmm is dominant, does not contain grains larger than 0.2mm generally and is of extreme sorting. By miscroscope observation. It was known that the red soil does not contain grains larger than 0.2mm. According to mentioned above, the red soil is of the outstanding characteristics of winddrift dust. it should be eolian deposit. Most geologists hold that loess .which was deposited in 2.4Ma ago and in cold-dry climate，is a sort of mark that a great deal of the eoliaa deposit of Cainozoic era began to deposite，but on the basis of the study in this paper, as early as before the loess began to deposit，a vast amount of deposit existed, There were possibly two kinds of form of climate that is as follows during the formation of the red soil.
1989, 7(3): 129-136.
Abstract:
44 sediment samples were collected from northeastern part of Cenual Pacific Ocean basin during 1985- 1986 cruise. These sediments were classified into six types: calcareous ooze, calcareous clay,siliceous clay, deep-sea clay, zeolite clay and zcolite rich clay. The distribution, characteristics and controlling factors of these sediments, as well as some relationship between the surface sediments and manganese nodules are discussed in this paper. Deep-sea clay which appears brown or dark brown is distributed widely on the sea Moor at below 5200m water depth. The contents of the coarse fractions in the deep-sea clay is Icss than 15%。and these arc composed dominantly of radiolarian remain and zeolite. The contents of clay is more than 85%. Calcareous sediments(calcareous ooze and calcareous clay) were distributed in the surround of hills. in where water depth is above CCD(5200m ).Its coarse fraction of which consists almost exclusively of the foraminifera shells, of which the contents range between 11%and 90% or so. Zcolite clay is dark brown. The contents of zcolite(phillipsite) in the zcolite clay.
44 sediment samples were collected from northeastern part of Cenual Pacific Ocean basin during 1985- 1986 cruise. These sediments were classified into six types: calcareous ooze, calcareous clay,siliceous clay, deep-sea clay, zeolite clay and zcolite rich clay. The distribution, characteristics and controlling factors of these sediments, as well as some relationship between the surface sediments and manganese nodules are discussed in this paper. Deep-sea clay which appears brown or dark brown is distributed widely on the sea Moor at below 5200m water depth. The contents of the coarse fractions in the deep-sea clay is Icss than 15%。and these arc composed dominantly of radiolarian remain and zeolite. The contents of clay is more than 85%. Calcareous sediments(calcareous ooze and calcareous clay) were distributed in the surround of hills. in where water depth is above CCD(5200m ).Its coarse fraction of which consists almost exclusively of the foraminifera shells, of which the contents range between 11%and 90% or so. Zcolite clay is dark brown. The contents of zcolite(phillipsite) in the zcolite clay.
