1983 Vol. 1, No. 4
column
Display Method:
1983, 1(4): 1-16.
Abstract:
Changguang coalfield is located in northwestern Zhejiang.The coal-bearing formations of the Late Permian are widely distributed in the lower Yangtze region and have long been known as the Longtan formation with depositional features and great amount of bark in coal seams.This paper deals mainly with the origin of bark liptobiolite and its depositional environment.As a result of the Permian tectonic movement,many large and small basins came into existence in South China where were deposited sandstone,siltstone,shale,thin一bedded limestone and coal seams.Most of the valuable coalfields were formed during this time.The coal-bearing formation in Changguang basin contains chiefly four coal groupsA.B,C and D,in which C coal seam is rather thick,its thickness may reach 1.3-2 m and especially its western part can be mined. C coal seam is usually interspersed with some lenses of skeletal limestone or shell limestone.Both these limestones consist of abundant marine fossils such as brachiopods, pelecypods,crinoids,etc.It is evident that these beds of skeletal limestone bearing marine fossils represent temporary inundatien of coastal swamp by the sea.Based on the sedimentary analysis,a set of sediments including C coal seam show the depositional features of the marine swamps lowlands.C coal seam is mainly dull bituminous coal whose structure is rather simple.It contains a large percentage of suberinite (average 67%)sometimes up to 80-95%,which indicates that there is a close relationship between the depositional environment and the Permian coal-forming plant communities.It is more important to note that the bark coals originate from the selective decomposition of plant materials,that other materials such as lignin,cellulose,protein and their diagenesis products are wholely decomposed and drifted by flowing water and that resistant materials become concentrated under a reducing condition.Hence the bark coal may also be called bark liptobiolite.The bark liptobiolite in this region can be grouped into two types:the first one which develops from plants after decomposition, forms coal in situ, and the second one is hypautochthonovs coal, which develops from plant remains transported not far fiom their original sites.These two types of coal occur more often in this coal basin than in other regions.Under the microscope, in reflected light is dark grey and usually shows orange-yellowish subcrinite fluorescence.Location:Niutoushan No.1 Vitrinite Romax0.77%,Suberinite Romax0.27%,Niu-toushan No. 6. Vitrinite Romax1.06%,Suberinite Romax0.67%,typical bark coal (suberinite above 80 %):Vr155.86%,Hr1 7.11%,SgQ 3.85%,Ag1 12.19%.Besides, pyrite and clay minerals are usually scattered in seams and these bituminous coals influenced by the sea are characterized by the presence of high sulphur (3.8-6.6%)The results suggest that these coal seams are formed in coastal marine swampy lowlands and the depositional environment is suitable for concentration of plant fragments.Obviously,the formation of bark coals may be affected generally by the following factors:depositional environment,the type of deposition and the coal-forming plant communities.
Changguang coalfield is located in northwestern Zhejiang.The coal-bearing formations of the Late Permian are widely distributed in the lower Yangtze region and have long been known as the Longtan formation with depositional features and great amount of bark in coal seams.This paper deals mainly with the origin of bark liptobiolite and its depositional environment.As a result of the Permian tectonic movement,many large and small basins came into existence in South China where were deposited sandstone,siltstone,shale,thin一bedded limestone and coal seams.Most of the valuable coalfields were formed during this time.The coal-bearing formation in Changguang basin contains chiefly four coal groupsA.B,C and D,in which C coal seam is rather thick,its thickness may reach 1.3-2 m and especially its western part can be mined. C coal seam is usually interspersed with some lenses of skeletal limestone or shell limestone.Both these limestones consist of abundant marine fossils such as brachiopods, pelecypods,crinoids,etc.It is evident that these beds of skeletal limestone bearing marine fossils represent temporary inundatien of coastal swamp by the sea.Based on the sedimentary analysis,a set of sediments including C coal seam show the depositional features of the marine swamps lowlands.C coal seam is mainly dull bituminous coal whose structure is rather simple.It contains a large percentage of suberinite (average 67%)sometimes up to 80-95%,which indicates that there is a close relationship between the depositional environment and the Permian coal-forming plant communities.It is more important to note that the bark coals originate from the selective decomposition of plant materials,that other materials such as lignin,cellulose,protein and their diagenesis products are wholely decomposed and drifted by flowing water and that resistant materials become concentrated under a reducing condition.Hence the bark coal may also be called bark liptobiolite.The bark liptobiolite in this region can be grouped into two types:the first one which develops from plants after decomposition, forms coal in situ, and the second one is hypautochthonovs coal, which develops from plant remains transported not far fiom their original sites.These two types of coal occur more often in this coal basin than in other regions.Under the microscope, in reflected light is dark grey and usually shows orange-yellowish subcrinite fluorescence.Location:Niutoushan No.1 Vitrinite Romax0.77%,Suberinite Romax0.27%,Niu-toushan No. 6. Vitrinite Romax1.06%,Suberinite Romax0.67%,typical bark coal (suberinite above 80 %):Vr155.86%,Hr1 7.11%,SgQ 3.85%,Ag1 12.19%.Besides, pyrite and clay minerals are usually scattered in seams and these bituminous coals influenced by the sea are characterized by the presence of high sulphur (3.8-6.6%)The results suggest that these coal seams are formed in coastal marine swampy lowlands and the depositional environment is suitable for concentration of plant fragments.Obviously,the formation of bark coals may be affected generally by the following factors:depositional environment,the type of deposition and the coal-forming plant communities.
1983, 1(4): 30-38.
Abstract:
The sponge reef exists in the second member of the Changxing formation,Upper Permian.M ost reef-building organisms consist of porataoidea and aporata-oidea of sphinctozoa and so me species of fibrous spongia,while stromatoporoids,bryozoa,coral colonies,hydrozoa and tubiphytes come second. Non-skeletal blue-algae have formed binding-coat or coat. Their abundance influences the reef-building mode.Reef-liked organisms are mostly composed of brachiopoda,gastropod,crinoidea,bryozoa of cryptomata and foraminiferas The reef develop went process can be divided into three stages: (1)Initial stage:Bafflestone is formed but algal-binding process is very weak。(2)Vigorous stage:Reef-building organisms are so abundant and vigorous that frameworkstone is constructed。Algal-bindsting process gradually becomes strong,and bindstone is formed at the late stage.(3)Decay stage:Algal-bindstone develops.The formation of the dolomite cap of 15 meterthick and the porphyritic dolomite of different sizes of the rest of the reef indicate that later on the top of the reefis exposed to the sea surface and dorag dolomitization takes place.Fram eworkporositp is successively filled by fibrous and bladed spar calcites.Silicifi cationdevelop later because silica is found to replace coarse spar calcite.It is very common in China that there are siliceous belts and large nodules in the carbonate rock of the Upper Permian. But such a silicified phenomenon has not been found in the Lichuan sponge reef. Silicification is so weak that there are only siliceous micro-nodules in the reef, ranging from 0.1 mm to 1 mm in size,the largest being 5mm and the smallest 0.01mm. Their section is nearly round or irregular. Silica mainly replaces carbonate organisms and minerals,silicification can not be found near and at the reef top of dolomite cap. Silica mostly replaces fibrous and bladed calcite cements,then grained spar calcite cements and partly the skeleton of bryozoa and sponge.The dimension and shape of nodules are often controlled by mineral fabric andthe growth of the nodules is usually restricted by the width of fibrous and bladed calcite cement belts. The crystal habit of nodules makes the section oblate-long or elongate. The nodules at the bend in a cement belt take flexural shape.The nodules are mainly composed of elongate quartz and a bit of lutecite and microlitic quartz,and they are arranged in a radiating or semi-radiating way except microlitic quartz. As there are residual crystal and insoluble impurites of calcite, the nodules are characterized by the incomplete replacement. When observed under a simple nicol,the remains of fibrous and bladed calcites in quartz-ferous nodule are dirty brown-grey in color and keep the optic character of calcite fib under crossed nicols. The nodule outer margin in a thin section takes clean and transparent hackle shape.In addition,a few nodules arc composed of microlitic quartz,too. The skeletal crusts of brachiopods,foraminiferas and ostracods are replaced by euhedral grained and microlitic quartz under silicfication but the replacements are eetremely incomplete.The spectral aaalysis shows that the silica content in the sponge reef is much lower (only 0.06-1%)than that in the carbonatite of the contemporaneous basin facies (6 %)and that in its underlying layey (10%).This results from abundant calcareous but few of siliceous organisms.The replacement relationship indicates that all siliceous nodules and authigenic quartz are formed by replacement and their formation is later than that of siliceous belt and large nodules of the carbonatite of non-reef facies. Perhaps the silica still results from the continuous dissolution of radiolarla and siliceous sponge spicules in the sediments of the contemporaneous basin and its underlying layer.As a result of the differential compaction,the silicic water flow into pore space of the reef. Later on,when the top of the reef is erposed to the sea surface,a gteat amount of fresh water begin to infiltrate and mix with silicic pore water.so the pH value becomes low.At the moment,the replacement of Si02 occur and mixed water gives rise to dolomitization.Because mixed water is unsaturated to calcite but is supersnturated to dolomite replacement does not take place in dolomite.It is obvious that the effect of silicification on the reservoir property of intercrystaline pore of dolomite is not important.
The sponge reef exists in the second member of the Changxing formation,Upper Permian.M ost reef-building organisms consist of porataoidea and aporata-oidea of sphinctozoa and so me species of fibrous spongia,while stromatoporoids,bryozoa,coral colonies,hydrozoa and tubiphytes come second. Non-skeletal blue-algae have formed binding-coat or coat. Their abundance influences the reef-building mode.Reef-liked organisms are mostly composed of brachiopoda,gastropod,crinoidea,bryozoa of cryptomata and foraminiferas The reef develop went process can be divided into three stages: (1)Initial stage:Bafflestone is formed but algal-binding process is very weak。(2)Vigorous stage:Reef-building organisms are so abundant and vigorous that frameworkstone is constructed。Algal-bindsting process gradually becomes strong,and bindstone is formed at the late stage.(3)Decay stage:Algal-bindstone develops.The formation of the dolomite cap of 15 meterthick and the porphyritic dolomite of different sizes of the rest of the reef indicate that later on the top of the reefis exposed to the sea surface and dorag dolomitization takes place.Fram eworkporositp is successively filled by fibrous and bladed spar calcites.Silicifi cationdevelop later because silica is found to replace coarse spar calcite.It is very common in China that there are siliceous belts and large nodules in the carbonate rock of the Upper Permian. But such a silicified phenomenon has not been found in the Lichuan sponge reef. Silicification is so weak that there are only siliceous micro-nodules in the reef, ranging from 0.1 mm to 1 mm in size,the largest being 5mm and the smallest 0.01mm. Their section is nearly round or irregular. Silica mainly replaces carbonate organisms and minerals,silicification can not be found near and at the reef top of dolomite cap. Silica mostly replaces fibrous and bladed calcite cements,then grained spar calcite cements and partly the skeleton of bryozoa and sponge.The dimension and shape of nodules are often controlled by mineral fabric andthe growth of the nodules is usually restricted by the width of fibrous and bladed calcite cement belts. The crystal habit of nodules makes the section oblate-long or elongate. The nodules at the bend in a cement belt take flexural shape.The nodules are mainly composed of elongate quartz and a bit of lutecite and microlitic quartz,and they are arranged in a radiating or semi-radiating way except microlitic quartz. As there are residual crystal and insoluble impurites of calcite, the nodules are characterized by the incomplete replacement. When observed under a simple nicol,the remains of fibrous and bladed calcites in quartz-ferous nodule are dirty brown-grey in color and keep the optic character of calcite fib under crossed nicols. The nodule outer margin in a thin section takes clean and transparent hackle shape.In addition,a few nodules arc composed of microlitic quartz,too. The skeletal crusts of brachiopods,foraminiferas and ostracods are replaced by euhedral grained and microlitic quartz under silicfication but the replacements are eetremely incomplete.The spectral aaalysis shows that the silica content in the sponge reef is much lower (only 0.06-1%)than that in the carbonatite of the contemporaneous basin facies (6 %)and that in its underlying layey (10%).This results from abundant calcareous but few of siliceous organisms.The replacement relationship indicates that all siliceous nodules and authigenic quartz are formed by replacement and their formation is later than that of siliceous belt and large nodules of the carbonatite of non-reef facies. Perhaps the silica still results from the continuous dissolution of radiolarla and siliceous sponge spicules in the sediments of the contemporaneous basin and its underlying layer.As a result of the differential compaction,the silicic water flow into pore space of the reef. Later on,when the top of the reef is erposed to the sea surface,a gteat amount of fresh water begin to infiltrate and mix with silicic pore water.so the pH value becomes low.At the moment,the replacement of Si02 occur and mixed water gives rise to dolomitization.Because mixed water is unsaturated to calcite but is supersnturated to dolomite replacement does not take place in dolomite.It is obvious that the effect of silicification on the reservoir property of intercrystaline pore of dolomite is not important.
1983, 1(4): 49-60.
Abstract:
In accordance with our study,the ugper part of the middle Jurassic, the Nanling Group, in Beipiao district of Liaoning, is apparently- of Aeloian feature,either on sedimentary structure or texture, and it is affirmed that the Group is formed under a desert environment, mainly of aeloian, and in addition, carrying-water deposition.The deposit assemblage that is a multiple terrestrial detritus formation, may be subdivided into three members--the lower one, the middle one and the upper one. The lower member and the upper member consist of sandstone and conglomerate of multiple composition, which are mainly wadi deposits with lower maturity and intercalated with Aeolian matters. The middle member is composed of well-sorted quartz sandstone of Aeolian dune deposit, locally intercalated mith mudstone of small oasis deposit. On sequent, these constitute a symmetrical texture with the middle member as its main part, On lithololy, this Group is composed primarily of purplish red, dark purple and grey-white quartz sandstone, and secondarily, the detritus arkose, arkose and conglomerate, involving a great quantity of ventifacts within it. The composition texture maturity of quartz sandstone is relatively high, often showing a mono-mode and a bi-mode distribution. In general, it consists of 3-4 grades, mainly the medium-fine ones. The surface of quartz sand graitt in smooth, coated with desert varnish, and the ventifaces is possessed of pitted surface. All results determined from the cumulative probability curve, the sorting coefficient, the grade analysis and the roundness and sphericity, show that the depositional character is identical with that of modern desert.Sandstone of middle member develops tabulate and trough-shaped cross-bedding of big size (thickness of a set may be of 10-30m), The fine beds dip gently(10-15° in general) and there are also steeper ones, but the direction of inclination is variable. The foresets are steep in the upper part and gentle in the lower part.They tend to be horizontal near the bottom of a set and some fine beds expand radially in bundle form. There is often lagging ventifact deposit in the bottom of a set.Then, this area is a small erg ettvironment and a good continental drainage area formed on active tectonic background of the Nantianmen fault. It is situated in the tropicsubtropic zone(the paleo-equator being situated in 45-50° of modern north latitude). Owing to the effect of northeastward monsoon, it has formed hot desert environment of frequent storm. According to the development character(i.e. the progressive decrease in thickness and scale of cross-bedding sets etc. )of each members of the upper \anling Group, it shows that the climate of this area approaches wet and the desert environment is progressively replaced by a lake condition at the end of middle Jurassic。
In accordance with our study,the ugper part of the middle Jurassic, the Nanling Group, in Beipiao district of Liaoning, is apparently- of Aeloian feature,either on sedimentary structure or texture, and it is affirmed that the Group is formed under a desert environment, mainly of aeloian, and in addition, carrying-water deposition.The deposit assemblage that is a multiple terrestrial detritus formation, may be subdivided into three members--the lower one, the middle one and the upper one. The lower member and the upper member consist of sandstone and conglomerate of multiple composition, which are mainly wadi deposits with lower maturity and intercalated with Aeolian matters. The middle member is composed of well-sorted quartz sandstone of Aeolian dune deposit, locally intercalated mith mudstone of small oasis deposit. On sequent, these constitute a symmetrical texture with the middle member as its main part, On lithololy, this Group is composed primarily of purplish red, dark purple and grey-white quartz sandstone, and secondarily, the detritus arkose, arkose and conglomerate, involving a great quantity of ventifacts within it. The composition texture maturity of quartz sandstone is relatively high, often showing a mono-mode and a bi-mode distribution. In general, it consists of 3-4 grades, mainly the medium-fine ones. The surface of quartz sand graitt in smooth, coated with desert varnish, and the ventifaces is possessed of pitted surface. All results determined from the cumulative probability curve, the sorting coefficient, the grade analysis and the roundness and sphericity, show that the depositional character is identical with that of modern desert.Sandstone of middle member develops tabulate and trough-shaped cross-bedding of big size (thickness of a set may be of 10-30m), The fine beds dip gently(10-15° in general) and there are also steeper ones, but the direction of inclination is variable. The foresets are steep in the upper part and gentle in the lower part.They tend to be horizontal near the bottom of a set and some fine beds expand radially in bundle form. There is often lagging ventifact deposit in the bottom of a set.Then, this area is a small erg ettvironment and a good continental drainage area formed on active tectonic background of the Nantianmen fault. It is situated in the tropicsubtropic zone(the paleo-equator being situated in 45-50° of modern north latitude). Owing to the effect of northeastward monsoon, it has formed hot desert environment of frequent storm. According to the development character(i.e. the progressive decrease in thickness and scale of cross-bedding sets etc. )of each members of the upper \anling Group, it shows that the climate of this area approaches wet and the desert environment is progressively replaced by a lake condition at the end of middle Jurassic。
1983, 1(4): 78-91.
Abstract:
The study of sedimentary facies and distribution of groundwater-bearing beds of modern alluvial fans may be applied to reconstruct the palaeogeographic environment and to estimate the rule of enrichment of oil-gas in a fanglomerate oil field.In elongated fault basins,the types of faults along the tR o sides of the basin often differ; one is a single deep-penetrating fault, the other is a series of step-faults.As a result ,the types of alluvial fans which are related to the activity of the faults also differ.They differ distinctively in the thickness and width of the accumulated beds, and in the texture and heterogeneity of the deposits.The alluvial fans related to single deep-penetrating fault are characterized by greater thickness which decre-ases from fanhead to the rim,and by smaller width,coarser pebbles and less heterogeneity of granulo m etry.In such alluvial fans,the difference in lithological cha- racters are mainly present a m ong the subfacies of fanhead,midfan and fanrim.The groundwater is well-distributed in the form of plane. The alluvial fans related to step faults are characterized by minor thickness,w hick increases from fanhead to the rim; by greater width, finer grain size and greater heterogeneity of granulo me- try. The lithology varies across the fan as along its axis.There are channel-flood subfacies and sheetflood subCacies.T he former consists of coarse-grains w hick con-tain little mud,thus presenting greater porosity and being more pervious,forming a belt of ground water-bearing beds. The latter is fine-grained, less pervious and groundwater-poor.It is present as wide slieets on both sides of the channelflood sub facies Through the trend-surface anaysis of the thickness,the clustered analysis of lithology,the size analysis of pebbles and the co m parison of different electro-lithologic profiles. The Third Member of the Upper Wuerhe Formation(Permian)of the No. 5 District of Klamaii Oil Field, }injiang, are considered as the type of alluvi-al fan deposits related to step-faults. The concentration of oil-gas in these fang-lomerates conforms quite well to the distribution of groundwater in modern alluvial fans of the same type.
The study of sedimentary facies and distribution of groundwater-bearing beds of modern alluvial fans may be applied to reconstruct the palaeogeographic environment and to estimate the rule of enrichment of oil-gas in a fanglomerate oil field.In elongated fault basins,the types of faults along the tR o sides of the basin often differ; one is a single deep-penetrating fault, the other is a series of step-faults.As a result ,the types of alluvial fans which are related to the activity of the faults also differ.They differ distinctively in the thickness and width of the accumulated beds, and in the texture and heterogeneity of the deposits.The alluvial fans related to single deep-penetrating fault are characterized by greater thickness which decre-ases from fanhead to the rim,and by smaller width,coarser pebbles and less heterogeneity of granulo m etry.In such alluvial fans,the difference in lithological cha- racters are mainly present a m ong the subfacies of fanhead,midfan and fanrim.The groundwater is well-distributed in the form of plane. The alluvial fans related to step faults are characterized by minor thickness,w hick increases from fanhead to the rim; by greater width, finer grain size and greater heterogeneity of granulo me- try. The lithology varies across the fan as along its axis.There are channel-flood subfacies and sheetflood subCacies.T he former consists of coarse-grains w hick con-tain little mud,thus presenting greater porosity and being more pervious,forming a belt of ground water-bearing beds. The latter is fine-grained, less pervious and groundwater-poor.It is present as wide slieets on both sides of the channelflood sub facies Through the trend-surface anaysis of the thickness,the clustered analysis of lithology,the size analysis of pebbles and the co m parison of different electro-lithologic profiles. The Third Member of the Upper Wuerhe Formation(Permian)of the No. 5 District of Klamaii Oil Field, }injiang, are considered as the type of alluvi-al fan deposits related to step-faults. The concentration of oil-gas in these fang-lomerates conforms quite well to the distribution of groundwater in modern alluvial fans of the same type.
1983, 1(4): 106-116.
Abstract:
Sinian sedimentary manganese carbonate deposits are a main type of manganese deposits in Guizhou.The deposits in stratoid and Ienticular form lie at the bottom of black carbon and silty claystones overlain by the lower Sinian Nantao formation.They are located at the same horizon as that of Xiangtan's manganese deposits. The manganeous horizon is widely distributed R-ith distinct boundary and stable form in the east of Guizhou,which may be compared with the same horizon of neighbouring provinces.It represents a specific geological environment in geological history.Therefore.it may be named" Datangpo Formation".The Datangpo Formation is a series of claystonc rich in organic carbon and fossil algae with distinct rhythmic laminae and tide-beddings.They belong to the sediments formed in the middle stage of the Early Sinian, i.e. sapropel—clay(algae-sheet fades and nearshore environment dominate)—silt. In the geological history there existed a process of development from Dawu glacial age to Datangpo interglacial age in the east of Guizhou during the middle stage of the Earl- Sinian epoch. The general configuration originated by the glacier in the Dawu glacial age,which hadn‘t undergone severe denudation.controls the distribution and character of sedimentary- facies of the Datangpo age.Then its paleogeographic environment may be divided into three facies zones and eight sedimentary facies,that is,continental,transitional and marine facies zones.The continental facies zone,composed of Sichuan一Guizhou old land and characterized by denudation,is mainly distributed in the centre of Guizhou.These sediments occur locally in the depressed basins and valleys and form the sediments of inland lake and alluvial facies.The alternating section of continent and sea with unstable environment forms a narrow transitional fades zone. They are mainly composed of river delta.shoreline sand flats—sand bar and Shoreline mud flats facies and develop in the areas such as Yinjiang. Jiangkou.Yubing. Sansui, Tai jiang and Sandu Counties.Marine widely distributed in the east of Guizhou.The major facies zone of rhodochrosite deposits.in particular the sapropelic algac-sheet facies is the direct sedimentary area of the rhodochrositc deposits.In addition,there are the sediments of shallow sea facies.which may be divided into two kinds restricted nearshore shallow sea facies and open shallow shelf sea facics.According to their characteristics and tectonics,the former occurs in the northeast of Guizhou and the latter the southeast of Guizhou.On the basis of texture and structure of the rhodochrosite ore and characters of associated mineral MnCO3,which may be considered as the immediate deposition of Mn(HCO3)2.Clay mineral associated with rhodochrosite is derived from the denuded areas of old land and is the result of the precipitation of suspended matter.Origin of rhodochrosite ore is w ith close relation to the activities of algae.Because of the specific geological condition in the late Precambrian,marine water rich in CO2 can mane a great deal of Mn2+ exist in it. In the sapropelic algae-sheet environment. a great amount of CO2 are absorbed by the algae photosynthesis.MnCO3 may immediately precipitate in the lower part of the sapropelic algae--sheet facies.After the diagenesis they become the present carbonaceous rhoclochrosite bed.The favourable facies of rhodoc:hrosite deposits is widespread at Xiushan,Songto,Wanshan,Tianzhu,Taijiang and Sandu Counties.
Sinian sedimentary manganese carbonate deposits are a main type of manganese deposits in Guizhou.The deposits in stratoid and Ienticular form lie at the bottom of black carbon and silty claystones overlain by the lower Sinian Nantao formation.They are located at the same horizon as that of Xiangtan's manganese deposits. The manganeous horizon is widely distributed R-ith distinct boundary and stable form in the east of Guizhou,which may be compared with the same horizon of neighbouring provinces.It represents a specific geological environment in geological history.Therefore.it may be named" Datangpo Formation".The Datangpo Formation is a series of claystonc rich in organic carbon and fossil algae with distinct rhythmic laminae and tide-beddings.They belong to the sediments formed in the middle stage of the Early Sinian, i.e. sapropel—clay(algae-sheet fades and nearshore environment dominate)—silt. In the geological history there existed a process of development from Dawu glacial age to Datangpo interglacial age in the east of Guizhou during the middle stage of the Earl- Sinian epoch. The general configuration originated by the glacier in the Dawu glacial age,which hadn‘t undergone severe denudation.controls the distribution and character of sedimentary- facies of the Datangpo age.Then its paleogeographic environment may be divided into three facies zones and eight sedimentary facies,that is,continental,transitional and marine facies zones.The continental facies zone,composed of Sichuan一Guizhou old land and characterized by denudation,is mainly distributed in the centre of Guizhou.These sediments occur locally in the depressed basins and valleys and form the sediments of inland lake and alluvial facies.The alternating section of continent and sea with unstable environment forms a narrow transitional fades zone. They are mainly composed of river delta.shoreline sand flats—sand bar and Shoreline mud flats facies and develop in the areas such as Yinjiang. Jiangkou.Yubing. Sansui, Tai jiang and Sandu Counties.Marine widely distributed in the east of Guizhou.The major facies zone of rhodochrosite deposits.in particular the sapropelic algac-sheet facies is the direct sedimentary area of the rhodochrositc deposits.In addition,there are the sediments of shallow sea facies.which may be divided into two kinds restricted nearshore shallow sea facies and open shallow shelf sea facics.According to their characteristics and tectonics,the former occurs in the northeast of Guizhou and the latter the southeast of Guizhou.On the basis of texture and structure of the rhodochrosite ore and characters of associated mineral MnCO3,which may be considered as the immediate deposition of Mn(HCO3)2.Clay mineral associated with rhodochrosite is derived from the denuded areas of old land and is the result of the precipitation of suspended matter.Origin of rhodochrosite ore is w ith close relation to the activities of algae.Because of the specific geological condition in the late Precambrian,marine water rich in CO2 can mane a great deal of Mn2+ exist in it. In the sapropelic algae-sheet environment. a great amount of CO2 are absorbed by the algae photosynthesis.MnCO3 may immediately precipitate in the lower part of the sapropelic algae--sheet facies.After the diagenesis they become the present carbonaceous rhoclochrosite bed.The favourable facies of rhodoc:hrosite deposits is widespread at Xiushan,Songto,Wanshan,Tianzhu,Taijiang and Sandu Counties.
1983, 1(4): 124-130.
Abstract:
According to the depositional conditions,the Weso一Cainozoic continental sedi-ments are suggested to be divided into three kinds of environment in 12 facics:(1)Underwater depositional environment including deeplake facies,semi-deep lake facies,shallow lake facies.near-lake facies,salt lake facies and turbiditc facies;(2)transitional depositional environmeat including deltaic facies and marsh facics;(3)Subaerial depositioaal environment including fluviatile facies,pluvial facies,piedmont facies and aeolian facies.A map of depositional pattern for some of the Meso-Cenozoic oil and gas basins in China is、worked out based on the distribution of sedimentary facies of their oil-bearing rock series.The study of the continental depositional patterns of any oil and gas basins is of great significance to their exploration.Oil pools in any basins occur mostly in the oil-generation depressions and their environs,while the deep-lake facies and the semi-deep lake facies are both the region of distribution of source rocks and the center of deposition.so the research work serves as a useful guide to the discover of oil.丁he author believes that climate and tectonic movements are the two factors controlling the distribution and development of sedimentary facies.As for the tectonic movement occurring in the Meso一Cenozoic time,the author tries to classify the basins into three types:compressive, tensile and transitional,and gives a brief description of the distributional characteristics of sedimentary- facies in various types of basin.
According to the depositional conditions,the Weso一Cainozoic continental sedi-ments are suggested to be divided into three kinds of environment in 12 facics:(1)Underwater depositional environment including deeplake facies,semi-deep lake facies,shallow lake facies.near-lake facies,salt lake facies and turbiditc facies;(2)transitional depositional environmeat including deltaic facies and marsh facics;(3)Subaerial depositioaal environment including fluviatile facies,pluvial facies,piedmont facies and aeolian facies.A map of depositional pattern for some of the Meso-Cenozoic oil and gas basins in China is、worked out based on the distribution of sedimentary facies of their oil-bearing rock series.The study of the continental depositional patterns of any oil and gas basins is of great significance to their exploration.Oil pools in any basins occur mostly in the oil-generation depressions and their environs,while the deep-lake facies and the semi-deep lake facies are both the region of distribution of source rocks and the center of deposition.so the research work serves as a useful guide to the discover of oil.丁he author believes that climate and tectonic movements are the two factors controlling the distribution and development of sedimentary facies.As for the tectonic movement occurring in the Meso一Cenozoic time,the author tries to classify the basins into three types:compressive, tensile and transitional,and gives a brief description of the distributional characteristics of sedimentary- facies in various types of basin.
1983, 1(4): 17-29.
Abstract:
According to the domestic and foreign data and experimental results obtained from analysis,brief discussion have been gir-en on the amount and characteristics of gas and liquid hydrocarbons produced by organic m atter of coal-bearing strata during the different stages of coal formation,as well as the effect of macerals upon nature and composition of the products.In differentiation from hydrocarbons produced by source rocks, the liquid hydrocarbons originating from coal are composed of special oils,such as high war oil and lour mature light oil, especially the Latter does not erist in hydrocarbon originating from oil.The oil formation threshuld depth of high war oil is usually deeper than,but the threshold depth of low mature oil is shallower than that of typical sapropelic source rocks. All these characters are controlled by the nature and composition of macerals.Large amount of light oil rich in terpanes is produced from Fushun resins of low maturity in heating eyperiments. A scheme diagram of evolutionary stages of coal gas has been proposed.The relationships between pairs as reformation process and evolution of petroleum,metallic source strata and source rocks, host rock strata and reservoir rocks,migration of metallic elements and that of petroleum have been discussed in terms of grimary study of organic matter and lots of asphalts associated with some strata-bound ore deposits, as well as two eacamples of strata-bound ores.Solid asphalts can be divided into syngenetic-diagenetic asphalts,epigenetic (reformational) asphalts and hypergenetic asphalts.Epigenetic asphalts are also called reservoir (thermal metamorphosed) asphalts,representing one of the two thermal metamorphosed end products of oils within reservoirs.The significance of the study on origin of paleo-oil traps (thermal cracking methane gas field)and certain strata-bound ores has been discussed briefly. It has been proposed to predict the intensity and history of reformation process of strata-bound ores by the study of nature,composition and evolutionary- stage of organic matter and different kinds of asphalt in the ore deposits.
According to the domestic and foreign data and experimental results obtained from analysis,brief discussion have been gir-en on the amount and characteristics of gas and liquid hydrocarbons produced by organic m atter of coal-bearing strata during the different stages of coal formation,as well as the effect of macerals upon nature and composition of the products.In differentiation from hydrocarbons produced by source rocks, the liquid hydrocarbons originating from coal are composed of special oils,such as high war oil and lour mature light oil, especially the Latter does not erist in hydrocarbon originating from oil.The oil formation threshuld depth of high war oil is usually deeper than,but the threshold depth of low mature oil is shallower than that of typical sapropelic source rocks. All these characters are controlled by the nature and composition of macerals.Large amount of light oil rich in terpanes is produced from Fushun resins of low maturity in heating eyperiments. A scheme diagram of evolutionary stages of coal gas has been proposed.The relationships between pairs as reformation process and evolution of petroleum,metallic source strata and source rocks, host rock strata and reservoir rocks,migration of metallic elements and that of petroleum have been discussed in terms of grimary study of organic matter and lots of asphalts associated with some strata-bound ore deposits, as well as two eacamples of strata-bound ores.Solid asphalts can be divided into syngenetic-diagenetic asphalts,epigenetic (reformational) asphalts and hypergenetic asphalts.Epigenetic asphalts are also called reservoir (thermal metamorphosed) asphalts,representing one of the two thermal metamorphosed end products of oils within reservoirs.The significance of the study on origin of paleo-oil traps (thermal cracking methane gas field)and certain strata-bound ores has been discussed briefly. It has been proposed to predict the intensity and history of reformation process of strata-bound ores by the study of nature,composition and evolutionary- stage of organic matter and different kinds of asphalt in the ore deposits.
1983, 1(4): 39-48.
Abstract:
Control-ore facies is the sedimentary facies of controlling ore deposit formation,The fades may be a single or a composition of facies. The control-ore facies in the Yicheng Lead-Zinc Ore-Field is a complicated composition,The Yicheng Lead-Zinc Ore-field lies in the southeast of Gansu Province, It is well known that the ore-field is a famou strata-bound lead-zinc deposit. There exists a close relationship between the deposit and sedimentary facies (especially carbonatite sedimentary facies) of the Mfiddle Lower Devonian.The relationship shows that the control-ore facies is characterized by a polyfacies in the Xicheng Lead-Zinc Ore-field.This paper preliminarily presents a synthetical model of control-ore facies for discussion and reference.On the basis of the facies analyses of carbonatite and their adjoining rocks related to the ore, the control-ore facies in the Xicheng Lead-Zinc Ore-field can be divided into two control-ore facies areas and again subdivided into siy control-ore.facies groups and some control-ore fades.1. The platform fades area lies in the east of the Xicheng Lead-Zinc Ore-field.It is made up of the widespread and very thick carbonatite of the Lower Devonian.It is subdivided into three sedim entary facies groups related to the ore.(1)The finger hill-beach facies group of platform edge is a“finger" of the carbonatite platform. There are two "fingers'(Changba and Bi jiashan)in the Xicheng Lead-Zinc Ore-field. The Changba finger hill-beach facies group is by far the most typical cxample. The facies group may be subdivided into four control-ore facies、biological hill(reef)facies(controlling ore-body No. I of Changba),back hill depression fades(controlling ore bodies No. I I and VIII of Changba), front hill depression facies(controlling.No. III of Lijiagou)and biological beach or sand facies(controlling No. I andII of Lijiagou).(2)The platform facies group is made up of tvco control-ore facies:intraplatform ridge facies (controlling Xiaowanli ore deposit).andplatform cvaporation facies(controlling Guanzigou ore doposit).(3)The intraplatform depression facies group consists of two control-ore facies:stagnant depression facies(controlling Heitangou copper deposit) and depre-ssion ridge fades (controlling Laodongshan manifestation etc.).2. The basin facies area is a widely distributed in the Xicheng Ore-field besides platform facics areas. It is:,set of basin facies sediments of shallow sea of the Rliddle Devonian, and can be subdivided into three sedimentary facies groups of control-ore.(1)The biological hill(reef)facies group is an isolated hill(reef)in the basin fades area, for example, Luoba ore deposit, It is made up of two control-ore facies:the biological hill(reef) facies and back hill fades in close connection with the ore.(2)The biostrome reef-beach facies is a thick carbonatite bed in argillaceous sediments of the basin facies area, hor example.Dengjiashan and Yeshuihe ore deposits occur in the thinning out part of the reef-beach facies or in the part near the contact zone with back beach facies.(3)The spot reef facies(group)is made up of some little coral reef bodies in the basin facies area, and these little reef bodies can be completely replaced by galenite and sphalerite,From what we have mentioned above, some regularities are suggested as follows.Both facies areas:the carbonatite platform facies of the Lower Devonian and the basin facies area of the Middle Devonian control all the Xicheng Lead-Zinc ore-feild.The facies group controls the ore zone. For eiample, the finger hill-beach facies group of the platform edge controls all the Changba ore-zone. However, the depression, the hill and the beach control individual ore deposits or ore-bodies.All the characteristics the synthetical model of of the control-ore facies are synthesized and simulated as control-ore facies as shown in Fig. 2.
Control-ore facies is the sedimentary facies of controlling ore deposit formation,The fades may be a single or a composition of facies. The control-ore facies in the Yicheng Lead-Zinc Ore-Field is a complicated composition,The Yicheng Lead-Zinc Ore-field lies in the southeast of Gansu Province, It is well known that the ore-field is a famou strata-bound lead-zinc deposit. There exists a close relationship between the deposit and sedimentary facies (especially carbonatite sedimentary facies) of the Mfiddle Lower Devonian.The relationship shows that the control-ore facies is characterized by a polyfacies in the Xicheng Lead-Zinc Ore-field.This paper preliminarily presents a synthetical model of control-ore facies for discussion and reference.On the basis of the facies analyses of carbonatite and their adjoining rocks related to the ore, the control-ore facies in the Xicheng Lead-Zinc Ore-field can be divided into two control-ore facies areas and again subdivided into siy control-ore.facies groups and some control-ore fades.1. The platform fades area lies in the east of the Xicheng Lead-Zinc Ore-field.It is made up of the widespread and very thick carbonatite of the Lower Devonian.It is subdivided into three sedim entary facies groups related to the ore.(1)The finger hill-beach facies group of platform edge is a“finger" of the carbonatite platform. There are two "fingers'(Changba and Bi jiashan)in the Xicheng Lead-Zinc Ore-field. The Changba finger hill-beach facies group is by far the most typical cxample. The facies group may be subdivided into four control-ore facies、biological hill(reef)facies(controlling ore-body No. I of Changba),back hill depression fades(controlling ore bodies No. I I and VIII of Changba), front hill depression facies(controlling.No. III of Lijiagou)and biological beach or sand facies(controlling No. I andII of Lijiagou).(2)The platform facies group is made up of tvco control-ore facies:intraplatform ridge facies (controlling Xiaowanli ore deposit).andplatform cvaporation facies(controlling Guanzigou ore doposit).(3)The intraplatform depression facies group consists of two control-ore facies:stagnant depression facies(controlling Heitangou copper deposit) and depre-ssion ridge fades (controlling Laodongshan manifestation etc.).2. The basin facies area is a widely distributed in the Xicheng Ore-field besides platform facics areas. It is:,set of basin facies sediments of shallow sea of the Rliddle Devonian, and can be subdivided into three sedimentary facies groups of control-ore.(1)The biological hill(reef)facies group is an isolated hill(reef)in the basin fades area, for example, Luoba ore deposit, It is made up of two control-ore facies:the biological hill(reef) facies and back hill fades in close connection with the ore.(2)The biostrome reef-beach facies is a thick carbonatite bed in argillaceous sediments of the basin facies area, hor example.Dengjiashan and Yeshuihe ore deposits occur in the thinning out part of the reef-beach facies or in the part near the contact zone with back beach facies.(3)The spot reef facies(group)is made up of some little coral reef bodies in the basin facies area, and these little reef bodies can be completely replaced by galenite and sphalerite,From what we have mentioned above, some regularities are suggested as follows.Both facies areas:the carbonatite platform facies of the Lower Devonian and the basin facies area of the Middle Devonian control all the Xicheng Lead-Zinc ore-feild.The facies group controls the ore zone. For eiample, the finger hill-beach facies group of the platform edge controls all the Changba ore-zone. However, the depression, the hill and the beach control individual ore deposits or ore-bodies.All the characteristics the synthetical model of of the control-ore facies are synthesized and simulated as control-ore facies as shown in Fig. 2.
1983, 1(4): 61-77.
Abstract:
Qaidam basin is the Mesozoic and Cenozoic inland basin, where the Tertiary strata of developing abnormal formation pressure is mainly a suit of lake facies deposits of semi-alkaline water-alkaline water under dry climate. During the Ter-tiary period, this basin was an area of continuous deposition in a wide range, in the center of which shore-deep lake facies was developed, and the maximum area of lake basin was 50000 km}. "1'he rate of deposition generally was about 0.1-0.2mm/yr, the maximum being 0.56mm/yr.The abnormal formation pressures are found in、arious areas of relatively depressed region, In these areas the Pressure gradient increases with the depth.Vertically the formation pressure may be divided into three zones the normal pressure zone, the transitional zone and the abnormal pressure zone.The abnormal pressure is found below 3200 m depth, and its pressure gradients are from 0.14 to 0.22atm/m. With regard to the cause of abnormal formation pressure of this region. the authors' ideas are as follows:(1)Compaction unequilibrium caused by lack of permeable bed and rapid loading:In the process of sedimentation, the gravity load causes sediments to compact and lose porosity. The porosity reduces rapidly with the depth during the early stage of compaction and then retards. Until the porosity of argillaceous or Shales reaches about 6%,the expulsion of the pore fluid is resisted and the sediments become overpressured.On lithology,abnormal pressure primarily occurs in the gone consisting chiefly of fine-grained rocks and its upper half part rich in marl in No. 1 Yuejin area.In the interbedded strata of sandstone and shale, the excess pressure may also occur as long as the overlying sediments have a low permeability and the rate of deposition is rapid enough when the abnormal pressure is produced.(2)The effect of temperature:Within this basin, the actual average rate of pore-pressure increase since isolation is 0.31 arm/m, significantly higher than 0.23 atm/m of the average overburden-pressure gradient. This shows obviously that there is the aquathermal pressure effect. Owing to the incompletion of the isolation,the escape of pore water may occur, and the actual amount of pressure increases since isolation is greatly lower than the value calculated according to the temperature pressure-density diagram by Barker.(3)The montmorillonite-illite conversion and dehydration are not the prerequisites for the cause of abnormal pressure:.}16normal pressure, even super pressure, occurs below the depth of 4000m of Han 2 Well, but in the sequence there is not any montmorillonite content from shallow to deep. In contrast with this,some montmorillonites occur above 2400 m depth of Yue 110 well, where the abnormal pressure can also be found. The most abundant content of montmorillonite in this sequence, however, is only 20%,so the volume increase and pressure increase of pore fluid caused by dehydration are limited. These facts have shown that the dehydration of montmorillonites is nei ther a prerequisite nor an important factor in the generation of abnormal pressure.(4)High pressure zone is not always characterized by undercompaction in the shales. This might be caused by the fact that the match relation of lithological characters of abnormal pressure zone and its overlying strata is different from that of the general case.(5)The comparison of depth and age of the strata with abnormal formation pressure between No. 1 Yuejin area and Han 2 Well indicates that the compaction degree of pelitic rocks is affected by the age. At the same depth, the older the strata age is, the greater the compaction will be.In addition, the possibility can not be ruled out that the growth fault may cause the isolation in lateral for abnormal pressure zone, and the volume expansion produced by thermal-degradation of organic matter after the source rock entering the threshold depth of oil may also enhance the formation pressure.
Qaidam basin is the Mesozoic and Cenozoic inland basin, where the Tertiary strata of developing abnormal formation pressure is mainly a suit of lake facies deposits of semi-alkaline water-alkaline water under dry climate. During the Ter-tiary period, this basin was an area of continuous deposition in a wide range, in the center of which shore-deep lake facies was developed, and the maximum area of lake basin was 50000 km}. "1'he rate of deposition generally was about 0.1-0.2mm/yr, the maximum being 0.56mm/yr.The abnormal formation pressures are found in、arious areas of relatively depressed region, In these areas the Pressure gradient increases with the depth.Vertically the formation pressure may be divided into three zones the normal pressure zone, the transitional zone and the abnormal pressure zone.The abnormal pressure is found below 3200 m depth, and its pressure gradients are from 0.14 to 0.22atm/m. With regard to the cause of abnormal formation pressure of this region. the authors' ideas are as follows:(1)Compaction unequilibrium caused by lack of permeable bed and rapid loading:In the process of sedimentation, the gravity load causes sediments to compact and lose porosity. The porosity reduces rapidly with the depth during the early stage of compaction and then retards. Until the porosity of argillaceous or Shales reaches about 6%,the expulsion of the pore fluid is resisted and the sediments become overpressured.On lithology,abnormal pressure primarily occurs in the gone consisting chiefly of fine-grained rocks and its upper half part rich in marl in No. 1 Yuejin area.In the interbedded strata of sandstone and shale, the excess pressure may also occur as long as the overlying sediments have a low permeability and the rate of deposition is rapid enough when the abnormal pressure is produced.(2)The effect of temperature:Within this basin, the actual average rate of pore-pressure increase since isolation is 0.31 arm/m, significantly higher than 0.23 atm/m of the average overburden-pressure gradient. This shows obviously that there is the aquathermal pressure effect. Owing to the incompletion of the isolation,the escape of pore water may occur, and the actual amount of pressure increases since isolation is greatly lower than the value calculated according to the temperature pressure-density diagram by Barker.(3)The montmorillonite-illite conversion and dehydration are not the prerequisites for the cause of abnormal pressure:.}16normal pressure, even super pressure, occurs below the depth of 4000m of Han 2 Well, but in the sequence there is not any montmorillonite content from shallow to deep. In contrast with this,some montmorillonites occur above 2400 m depth of Yue 110 well, where the abnormal pressure can also be found. The most abundant content of montmorillonite in this sequence, however, is only 20%,so the volume increase and pressure increase of pore fluid caused by dehydration are limited. These facts have shown that the dehydration of montmorillonites is nei ther a prerequisite nor an important factor in the generation of abnormal pressure.(4)High pressure zone is not always characterized by undercompaction in the shales. This might be caused by the fact that the match relation of lithological characters of abnormal pressure zone and its overlying strata is different from that of the general case.(5)The comparison of depth and age of the strata with abnormal formation pressure between No. 1 Yuejin area and Han 2 Well indicates that the compaction degree of pelitic rocks is affected by the age. At the same depth, the older the strata age is, the greater the compaction will be.In addition, the possibility can not be ruled out that the growth fault may cause the isolation in lateral for abnormal pressure zone, and the volume expansion produced by thermal-degradation of organic matter after the source rock entering the threshold depth of oil may also enhance the formation pressure.
1983, 1(4): 93-105.
Abstract:
The Permian carbonate rocks are widespread in western Hubei.Apart from some clastic rocks at the bottom of Qixia Formation or at the top of Maokou Formation.most of them are carbonate deposits in ichich abundant foraminifears can be found。According to the origin一textural types carbonate rocks.indee of cater energy,and other biological assemblages associated with benthos foraminifera.the carbonate rocks can be subdivided into the folloivind 6 types of fades as well as 10 types of microfacies(Fig. I):a.Deep shelf It includes 3 types of microfacies(Plate 1,2).This facies is rich in argillo-calcareous composition and small bioclasts kith pelagic fauna,e.g.ammonite,sponge-spiculite.Algae are scarce.Among foraminifersa.the type of deep vrater such as iguiella.Palaeofusulina. Codonofusiella(P2),and Schwagerina,Chusenlla,Rugos-oschwagerina(P21),are predominant.b.Near shore shelf It contains 3 types of microfacics(Plate. 3).Sedimentary property and fossil assemblage show a lowtide open sea area near shore. There appear abundant green algae(Dasycladaceae).Adaptable fusulina such as Nankinella, Pisolina,Splraeru-lina and Verbeekina, as well as non-fusuline foraminiferas such as Pachyphloia,Padangia, Cribrogenerina, Climaeammia and so on.c.Tide shoal The type of rock is pelsparite(Plate 4,5)with red algae and green algae.This facies is formed in a lowtide high-energy and shallow water belt with normal salinity Fusulina specially thrive on,such as Yabeina Neosrhwagerina, Colania,Sumatrina, Pseudoliolina,Yerbeekinaand so on.Non-fusuline foraminiferas,Pachy-phloia,Cribrogerrerirra. Clinracammina and Nodosario are the most.d.Algal mud mound Algal limestone and micrite algal limestone are common types of carbonate rocks(Plate 7).Red algal Gymnorodiareae is well developed,while foraminifera has seldom grown to a thrifty colony·in whick a few of.Nankinella of Staffellidae are representative in early Lower Permian,and the genus of Srhwagerina arc abun-dant in Late Permian.Codonojusiella flourish in the Upper Permian.e.Intertidal flat The phyloid algal limestone is a representative of this facie (Plate 6).Nankin-ella is an adaptable fusulina to ecologic environment and becomes more prevalent.Non-fusuline foraminiferas including Eolasiodiscus, Glomospira and Nodosaria are the most abundant,the nest is Padangia. f.Restricted lagoon The rock type is silty micrite(Plate,8).The fossils consist of fragmental and scattered ostracodes,brachiopodas,bryozoans as well as Tubiphyfes,Vermiporella and Osagia. The species of non-fusulina or fusulina is simple,in which Padangia Perforata Lange are specially abundant. Only few Nankinella can be formed,which belongs to fusulina.The ecologic environment of foraminiferas is interpreted bt- means of studying on Permian carbonate microfacies and analysing their own architecture and morphologic function in this area.It is suggested that the foraminifera of Permian has not only obvious succession on vertical section,but is sensitive to living environment as well.There appear different units of foraminifera to various environments.
The Permian carbonate rocks are widespread in western Hubei.Apart from some clastic rocks at the bottom of Qixia Formation or at the top of Maokou Formation.most of them are carbonate deposits in ichich abundant foraminifears can be found。According to the origin一textural types carbonate rocks.indee of cater energy,and other biological assemblages associated with benthos foraminifera.the carbonate rocks can be subdivided into the folloivind 6 types of fades as well as 10 types of microfacies(Fig. I):a.Deep shelf It includes 3 types of microfacies(Plate 1,2).This facies is rich in argillo-calcareous composition and small bioclasts kith pelagic fauna,e.g.ammonite,sponge-spiculite.Algae are scarce.Among foraminifersa.the type of deep vrater such as iguiella.Palaeofusulina. Codonofusiella(P2),and Schwagerina,Chusenlla,Rugos-oschwagerina(P21),are predominant.b.Near shore shelf It contains 3 types of microfacics(Plate. 3).Sedimentary property and fossil assemblage show a lowtide open sea area near shore. There appear abundant green algae(Dasycladaceae).Adaptable fusulina such as Nankinella, Pisolina,Splraeru-lina and Verbeekina, as well as non-fusuline foraminiferas such as Pachyphloia,Padangia, Cribrogenerina, Climaeammia and so on.c.Tide shoal The type of rock is pelsparite(Plate 4,5)with red algae and green algae.This facies is formed in a lowtide high-energy and shallow water belt with normal salinity Fusulina specially thrive on,such as Yabeina Neosrhwagerina, Colania,Sumatrina, Pseudoliolina,Yerbeekinaand so on.Non-fusuline foraminiferas,Pachy-phloia,Cribrogerrerirra. Clinracammina and Nodosario are the most.d.Algal mud mound Algal limestone and micrite algal limestone are common types of carbonate rocks(Plate 7).Red algal Gymnorodiareae is well developed,while foraminifera has seldom grown to a thrifty colony·in whick a few of.Nankinella of Staffellidae are representative in early Lower Permian,and the genus of Srhwagerina arc abun-dant in Late Permian.Codonojusiella flourish in the Upper Permian.e.Intertidal flat The phyloid algal limestone is a representative of this facie (Plate 6).Nankin-ella is an adaptable fusulina to ecologic environment and becomes more prevalent.Non-fusuline foraminiferas including Eolasiodiscus, Glomospira and Nodosaria are the most abundant,the nest is Padangia. f.Restricted lagoon The rock type is silty micrite(Plate,8).The fossils consist of fragmental and scattered ostracodes,brachiopodas,bryozoans as well as Tubiphyfes,Vermiporella and Osagia. The species of non-fusulina or fusulina is simple,in which Padangia Perforata Lange are specially abundant. Only few Nankinella can be formed,which belongs to fusulina.The ecologic environment of foraminiferas is interpreted bt- means of studying on Permian carbonate microfacies and analysing their own architecture and morphologic function in this area.It is suggested that the foraminifera of Permian has not only obvious succession on vertical section,but is sensitive to living environment as well.There appear different units of foraminifera to various environments.
1983, 1(4): 117-123.
Abstract:
1.Characteristics of the carbonate flysch form ation a. It is characterized by conspicuous rhythms and every single rhythm is several centimetres or dozens of centimetres thick. It has a series of crinkled beddings of penecontemporaneous deformation formed by submarine slumping.b. Sedimentary structures other than bioherm are well bedded.c. Rudaceous limestones and bioherms are common.d.The formation is dark or dark gray but the light gray is seldom found.e. It is of marine lithofacies and its thickness is more than 1288.6-1600 m。2.Changes of sedimentary environment Two lithofacies are differentiated。One is turbidite fades found in Dabatou area,Ningyuan;It is composed of thin layers of limestone and dark marl,chert beds or siliceous mudstone are also representative;fossils are scares.Floating organ-ism Tentaculites fossil can occasionally be found.Bouma sequence and cronkled beddings of slumping type develop well,the sedimentary environment is from bathy-al to deep sea.The other facies is found in the outer area of Dabatou. It consists of massive reef,colluvial deposit in front of the reef,bioclastic limestone and porous dolo mite etc.The benthonic organisms such as Stromatoporoids,Brachiopods,coral ect.1'he environment is mainly in shallow sea and subtidal belt.
1.Characteristics of the carbonate flysch form ation a. It is characterized by conspicuous rhythms and every single rhythm is several centimetres or dozens of centimetres thick. It has a series of crinkled beddings of penecontemporaneous deformation formed by submarine slumping.b. Sedimentary structures other than bioherm are well bedded.c. Rudaceous limestones and bioherms are common.d.The formation is dark or dark gray but the light gray is seldom found.e. It is of marine lithofacies and its thickness is more than 1288.6-1600 m。2.Changes of sedimentary environment Two lithofacies are differentiated。One is turbidite fades found in Dabatou area,Ningyuan;It is composed of thin layers of limestone and dark marl,chert beds or siliceous mudstone are also representative;fossils are scares.Floating organ-ism Tentaculites fossil can occasionally be found.Bouma sequence and cronkled beddings of slumping type develop well,the sedimentary environment is from bathy-al to deep sea.The other facies is found in the outer area of Dabatou. It consists of massive reef,colluvial deposit in front of the reef,bioclastic limestone and porous dolo mite etc.The benthonic organisms such as Stromatoporoids,Brachiopods,coral ect.1'he environment is mainly in shallow sea and subtidal belt.
