1993 Vol. 11, No. 1
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Display Method:
1993, 11(1): 1-11.
Abstract:
Everyone of the ordinary functional groups in the organic compound approximates to a constant respectively. The topological volume of common functional groups themselves or between themselves are of harmonious and unified additivity. The authors have given a series of universal topological volume values of the common functional groups in the organic compound (see table)
Everyone of the ordinary functional groups in the organic compound approximates to a constant respectively. The topological volume of common functional groups themselves or between themselves are of harmonious and unified additivity. The authors have given a series of universal topological volume values of the common functional groups in the organic compound (see table)
1993, 11(1): 23-31.
Abstract:
Bogda Mountain in Xinjiang is composed of Carboniferous and Permain, but mainly the former. Permain only distributes at the foot of the mountain. The lower to middle part of Lower Permain is deep water beds made up of turbidity flow and other gravity flow deposites, under or above which large amounts of volcanic clastic tempestites have been found. They can be divided into seven types and further attributed to proximal and distal tempestites. Although Carboniferous and Permain systems of the south and north sides of Bogda Mountain have similar environment variations, i. e., from littoral zone and neritic shelf to bathyal slope, turning back to neritic shelf and littoral zone and then to continental enviroments, but the sedimentary features of of two sides, especially those of shallow water beds overlying deep water ones, are quite different. The north side consists of a sedimentary sequence developing dark fine-grained laminations, in which existed no large sedimentary textures occuring in tempestites and strong hydrodynamic environments, but those often found in a tidal flat, i. e., herringbone cross-beddings, lenticular beddings, vein beddings, wave beddings, which indcates that the beds were formed in a tidal flat that was obstacled and weaky hydrodynamic. In the similar beds on the south side frequently occurs not only proximal tempestites but also wave ripples, wave cross beddings, and reworked wave ripples formed in a wave-controlled environment, washing beddings, composed of coarse sandstones with high structure maturity, and oolite limestones further indicate that the environments were controlled by high-energy wave. As mentioned above, the palaeohydrodynamic environments of the two sides were quite different, so it is impossible for them to be formed in an united water body, which provides sedimentological evidences for Late Paleozoic Bogda islands arc. Because oceanic plate continuously subducted from north to south and volcanic products were formed, the two sides of Bogda Mountain finally were dissected into two different sedimentary basins with differend sedimentary characteristics.
Bogda Mountain in Xinjiang is composed of Carboniferous and Permain, but mainly the former. Permain only distributes at the foot of the mountain. The lower to middle part of Lower Permain is deep water beds made up of turbidity flow and other gravity flow deposites, under or above which large amounts of volcanic clastic tempestites have been found. They can be divided into seven types and further attributed to proximal and distal tempestites. Although Carboniferous and Permain systems of the south and north sides of Bogda Mountain have similar environment variations, i. e., from littoral zone and neritic shelf to bathyal slope, turning back to neritic shelf and littoral zone and then to continental enviroments, but the sedimentary features of of two sides, especially those of shallow water beds overlying deep water ones, are quite different. The north side consists of a sedimentary sequence developing dark fine-grained laminations, in which existed no large sedimentary textures occuring in tempestites and strong hydrodynamic environments, but those often found in a tidal flat, i. e., herringbone cross-beddings, lenticular beddings, vein beddings, wave beddings, which indcates that the beds were formed in a tidal flat that was obstacled and weaky hydrodynamic. In the similar beds on the south side frequently occurs not only proximal tempestites but also wave ripples, wave cross beddings, and reworked wave ripples formed in a wave-controlled environment, washing beddings, composed of coarse sandstones with high structure maturity, and oolite limestones further indicate that the environments were controlled by high-energy wave. As mentioned above, the palaeohydrodynamic environments of the two sides were quite different, so it is impossible for them to be formed in an united water body, which provides sedimentological evidences for Late Paleozoic Bogda islands arc. Because oceanic plate continuously subducted from north to south and volcanic products were formed, the two sides of Bogda Mountain finally were dissected into two different sedimentary basins with differend sedimentary characteristics.
1993, 11(1): 41-46.
Abstract:
The present paper discusses the features of mountain glacier sediment of Late Sinian in Beishan area that located in the west end of Inner Mongolia and northwest border of Gansu Province. The mountain glacier uplift belt, as an island-chain in Baihu-Mazongshan region, extends several handreds kilometers, its southern side is fault marine basin in Changheishan-Shuangyingshan-Wutongjing area, and the northern one is slope belt of sea basin, Pochengshan-Heidashan-Xichangjing, joint with the ocean area. The whole area appear'two depressions and one unlift"deposited basin framework. Tarim palacontinent, which located in the southern margin of the basin, was not covered with continental glacier by then. The central island chain uplift belt, consists of Middle Late Proterozoic Qingbaikou System, Jixian System and Changcheng System, was the source region of the palaeo-tillite. The authors found that the Xichangjing profile, as a representive one, is mostly developed. It shows that the Upper Sinian Xichangjing Group contains two sets i.e., the upper and the lower, of the paleoglacigenous rock, between them are the carbonate rock and terrigeneoussclastic sediments, which represent the warm climate condition at interglacial stage. It is suggested that there were two paleoglacial stage developed. In Beishan area, Xichangjing Group of Upper Sinian contacts with the underlying Dahuoluoshan Group, Qingbaikou Systam, and Pingtoushan Group, Jixian System with angular unconformity, and graduauly transited to the overlying Shuangyingshan formation of Cambrian System. The Pochengshan profile clearly indicated that the silicic rock of top of upper palaeo-tillite of Xichangjing Group showed gradual transitional contact with calcarenite containing Eoredlichia sp. fossil pieces, relevantly, the glacial pelitic conglomerate of transition bed from the upper glacigenous rock to Cambrian System contained sponge spicules and micropaleoflora fossils in Xichangjing region, some of which are correspond to that of upper Luoquan formation in Shaanxi and Henan Province. Therefore, it is proved that the upper glacigenous rock of Xichangjing Group belongs to Luoquan Ice Age, the paleoglaoigenous rocks under the interglacial deposits are the products of Nantuo Ice Age. In the area, tills from the mountain glacier were frequently carried away by ice rafting toward both side and droped in the distant places of the basins. As a result, the various environment marine deposit associations that containing tillites were formed.
The present paper discusses the features of mountain glacier sediment of Late Sinian in Beishan area that located in the west end of Inner Mongolia and northwest border of Gansu Province. The mountain glacier uplift belt, as an island-chain in Baihu-Mazongshan region, extends several handreds kilometers, its southern side is fault marine basin in Changheishan-Shuangyingshan-Wutongjing area, and the northern one is slope belt of sea basin, Pochengshan-Heidashan-Xichangjing, joint with the ocean area. The whole area appear'two depressions and one unlift"deposited basin framework. Tarim palacontinent, which located in the southern margin of the basin, was not covered with continental glacier by then. The central island chain uplift belt, consists of Middle Late Proterozoic Qingbaikou System, Jixian System and Changcheng System, was the source region of the palaeo-tillite. The authors found that the Xichangjing profile, as a representive one, is mostly developed. It shows that the Upper Sinian Xichangjing Group contains two sets i.e., the upper and the lower, of the paleoglacigenous rock, between them are the carbonate rock and terrigeneoussclastic sediments, which represent the warm climate condition at interglacial stage. It is suggested that there were two paleoglacial stage developed. In Beishan area, Xichangjing Group of Upper Sinian contacts with the underlying Dahuoluoshan Group, Qingbaikou Systam, and Pingtoushan Group, Jixian System with angular unconformity, and graduauly transited to the overlying Shuangyingshan formation of Cambrian System. The Pochengshan profile clearly indicated that the silicic rock of top of upper palaeo-tillite of Xichangjing Group showed gradual transitional contact with calcarenite containing Eoredlichia sp. fossil pieces, relevantly, the glacial pelitic conglomerate of transition bed from the upper glacigenous rock to Cambrian System contained sponge spicules and micropaleoflora fossils in Xichangjing region, some of which are correspond to that of upper Luoquan formation in Shaanxi and Henan Province. Therefore, it is proved that the upper glacigenous rock of Xichangjing Group belongs to Luoquan Ice Age, the paleoglaoigenous rocks under the interglacial deposits are the products of Nantuo Ice Age. In the area, tills from the mountain glacier were frequently carried away by ice rafting toward both side and droped in the distant places of the basins. As a result, the various environment marine deposit associations that containing tillites were formed.
1993, 11(1): 56-64.
Abstract:
Lunnan region locates in the southern part of Luntai County, belongs to the first class tectonic unit-Tabei rise belt in Tarim Basin. The top of the deep burial Ordovician carbonate rocks occurs in a NE- SW large burial hill. Ordovician System region only remained Upper Qiulitake Group of Lower Ordovician as a result of long-time surface exposition and intense weathering-denudation in Palaeozoic Era. Therock types are mainly the limestones formed in shallow water carbonite platform, which is one of the important oil-gas layers in this region. Many of the exploration wells have revealed that all of the oil-gas layers are distributed at 0-200m interval of the top of Upper Qiulitake Group. The rock cores of about 2000m long show that the palaeokarst is one of the important factors in controlling the development of reservoir. The palaeokarst is well-developed and characteried by clear vertical zonation at the top of Ordovician. From unconformity interface downward, the palaeokarst is divided into the following three zones: 1) surface karst zone, 2) transitional zone and 3) horizontal underground flow zone. Dissolved furrows, cracks and dolines are developed in zone 1; dissolution is not obvious in zone 2; large horizontal caves with the diameter up to 100m vertically, are developed in zone 3. The third zone feature is the most striking within this region. The overwhelming majority of the caves are filled. According to their features, four types of cave-fill deposits are identified: 1) debris flow, 2) underground river, 3) cave roof collapse and 4) gravitational sliding-dilapidation. The deposits in the horizontal caves are composed by the alternated sediments of debris flow, underground river and cave roof collapse. The filling deposits in the surface dissolved cracks and dolines are resulted from the sediments of debris flow and gravitational sliding-dilapidation. Sporo-pollen analysis in the cave-fill deposits shows that all of the sporoes are formed in Early Carboniferous. It can also be deduced from the analysis of the developing history of the tectonic and sediment of Tarim Basin that the tow- period horizontal caves are formed during the phasic rise of sea level in Early Carboniferous. Along-time stable underground water level is the necessity to the forming of horizontal caves. The destruction and reformation of palaeokarst can improve the porosity and permeability of original limestones. Three karst facies can be divided, which are, in descending order, 1) palaeosurface breccia, 2)cracked cave roof brecoia and facies 3)cave-fill. The breccias and associated deposits are arranged in two common association: lateral restricted (facies l)and lateral persistent(facies 2 and 3). In addition, facies 2, with the porosity of up to 13%, good permeability and the thickness of 5-30m, has the best reservoir property. It represents a cracked cave roof preserved and is the chief oil-gas layer. The reservoirs controlled by palaeokarst reflect intense heterogeneity both laterally and vertically, which is relative to the distribution of the karst breccia facies and associated deposits, and also to the faults as in the region well as their latger on activities.
Lunnan region locates in the southern part of Luntai County, belongs to the first class tectonic unit-Tabei rise belt in Tarim Basin. The top of the deep burial Ordovician carbonate rocks occurs in a NE- SW large burial hill. Ordovician System region only remained Upper Qiulitake Group of Lower Ordovician as a result of long-time surface exposition and intense weathering-denudation in Palaeozoic Era. Therock types are mainly the limestones formed in shallow water carbonite platform, which is one of the important oil-gas layers in this region. Many of the exploration wells have revealed that all of the oil-gas layers are distributed at 0-200m interval of the top of Upper Qiulitake Group. The rock cores of about 2000m long show that the palaeokarst is one of the important factors in controlling the development of reservoir. The palaeokarst is well-developed and characteried by clear vertical zonation at the top of Ordovician. From unconformity interface downward, the palaeokarst is divided into the following three zones: 1) surface karst zone, 2) transitional zone and 3) horizontal underground flow zone. Dissolved furrows, cracks and dolines are developed in zone 1; dissolution is not obvious in zone 2; large horizontal caves with the diameter up to 100m vertically, are developed in zone 3. The third zone feature is the most striking within this region. The overwhelming majority of the caves are filled. According to their features, four types of cave-fill deposits are identified: 1) debris flow, 2) underground river, 3) cave roof collapse and 4) gravitational sliding-dilapidation. The deposits in the horizontal caves are composed by the alternated sediments of debris flow, underground river and cave roof collapse. The filling deposits in the surface dissolved cracks and dolines are resulted from the sediments of debris flow and gravitational sliding-dilapidation. Sporo-pollen analysis in the cave-fill deposits shows that all of the sporoes are formed in Early Carboniferous. It can also be deduced from the analysis of the developing history of the tectonic and sediment of Tarim Basin that the tow- period horizontal caves are formed during the phasic rise of sea level in Early Carboniferous. Along-time stable underground water level is the necessity to the forming of horizontal caves. The destruction and reformation of palaeokarst can improve the porosity and permeability of original limestones. Three karst facies can be divided, which are, in descending order, 1) palaeosurface breccia, 2)cracked cave roof brecoia and facies 3)cave-fill. The breccias and associated deposits are arranged in two common association: lateral restricted (facies l)and lateral persistent(facies 2 and 3). In addition, facies 2, with the porosity of up to 13%, good permeability and the thickness of 5-30m, has the best reservoir property. It represents a cracked cave roof preserved and is the chief oil-gas layer. The reservoirs controlled by palaeokarst reflect intense heterogeneity both laterally and vertically, which is relative to the distribution of the karst breccia facies and associated deposits, and also to the faults as in the region well as their latger on activities.
1993, 11(1): 75-83.
Abstract:
Longtan coal series of Baohetang, Middle Hunan, has been investigated in detail by means of sedimentalogy, coal petrology and geochemistry. It is suggested that Baohetang coal was formed in delta environment. Most of coal seam I and n was formed in water-covered swamp that developed from distributary bay. The swamp was often influenced by river and tide. Boron contents of 17 coal samples range from 10 to 500ppm, concentrated in 50- 500ppm ( 15 samples) with an average of 152ppm. Comparition Baohetang coal with those deposited in fresh-water environment shows that the former is more boron-riched and which indicates brakish to semi-brakish water environment, moreover, their rations B / Ga, V / Zr, V / Ni. V / Zn and Sr / Ba are also different obviously. Fe2O3 contents of the 17 coal samples fall in the range of 4.54-20.07% with an average of 9.7%. and SO3 contents from 0.48-10. 85% ( average 5. 85% ) , ratio of ( Fe2O3+CaO+MgO) / (Sio2+Al2O3)from 0.08-0.78 with the mean of 0.34. Baohetang coal has striking features, mainly in coal petrology and Rock- Eval. The coal is characterised by low vitrinite content (from 30% to 52% ) , high sapropel groundmass and transitional macerals content 10%-21% and 25-49%. respectively) . Sapropel groundmass and some hydrogen-rich vitrinites exhausted a great deal of exudatinite, as a result, this makes the coal series contain a little oil. The coal has a higher production of S2, ranging from 198.40-212.40 ( mg / g) , suggests its oil forming potential. The aboundant transitional macerals must have been carried into the water-covered swamp from the oxidized zone of bank-back swamp by flood or tide. The paleocurrent analysis reveals that the sediments came mainly from the east (Shuangfeng-Guandimiao ancient land ?) and the north (Longshan uplift). but not from Xuefeng ancient land. Otherwise, three kinds of sedimental structures (bunch cross-bedding, derived ripple and washing-filling structure) have been discribed in detail, A coal-forming modle of Baohetang coal has been established.
Longtan coal series of Baohetang, Middle Hunan, has been investigated in detail by means of sedimentalogy, coal petrology and geochemistry. It is suggested that Baohetang coal was formed in delta environment. Most of coal seam I and n was formed in water-covered swamp that developed from distributary bay. The swamp was often influenced by river and tide. Boron contents of 17 coal samples range from 10 to 500ppm, concentrated in 50- 500ppm ( 15 samples) with an average of 152ppm. Comparition Baohetang coal with those deposited in fresh-water environment shows that the former is more boron-riched and which indicates brakish to semi-brakish water environment, moreover, their rations B / Ga, V / Zr, V / Ni. V / Zn and Sr / Ba are also different obviously. Fe2O3 contents of the 17 coal samples fall in the range of 4.54-20.07% with an average of 9.7%. and SO3 contents from 0.48-10. 85% ( average 5. 85% ) , ratio of ( Fe2O3+CaO+MgO) / (Sio2+Al2O3)from 0.08-0.78 with the mean of 0.34. Baohetang coal has striking features, mainly in coal petrology and Rock- Eval. The coal is characterised by low vitrinite content (from 30% to 52% ) , high sapropel groundmass and transitional macerals content 10%-21% and 25-49%. respectively) . Sapropel groundmass and some hydrogen-rich vitrinites exhausted a great deal of exudatinite, as a result, this makes the coal series contain a little oil. The coal has a higher production of S2, ranging from 198.40-212.40 ( mg / g) , suggests its oil forming potential. The aboundant transitional macerals must have been carried into the water-covered swamp from the oxidized zone of bank-back swamp by flood or tide. The paleocurrent analysis reveals that the sediments came mainly from the east (Shuangfeng-Guandimiao ancient land ?) and the north (Longshan uplift). but not from Xuefeng ancient land. Otherwise, three kinds of sedimental structures (bunch cross-bedding, derived ripple and washing-filling structure) have been discribed in detail, A coal-forming modle of Baohetang coal has been established.
1993, 11(1): 93-102.
Abstract:
There are 7 minerogenetic districts of middle Devonian, the important ones are the I ,II , III and IV .. and of late Devonian, V, VI, and VII. Generally, there are 2-3 girdles in one oolite, but sometimes the number can as large as 20 and as small as one , the later may be called the pseudoolites. Sometimes an oolite is a gel cumularspharolith without girdles and without nucleus and sometimes there are many girdles in oolites but without nucleus. Composition of the girdles of oolites and gel cumularspharolithes are automorphic crystals of micrograined hematite, chlorites, siderites or the mixture of the three minerals with some clay minerals (mainly is illite) , minute collphane. The nuclei are made of quartz debris in general. The matrix between oolites are made of automorphic crystal micrograined ferruginous minerals, clay minerals, minute collphane or their clastes and quartz clastes. Oolites, pseudoolites, cumularspharolithes are round, ellipsoidal in shape, 0.2-0.8mm in diameter, and all of them are in the same size. The content of oolitic ironstone TFe is 30-40% generally with the range of 27-28% to 40-46%. In China, the best sedimentary environment of Devonian oolitic ironstone is the region nearby the closed shallow water lagoon , where reserved 60% of total Devonian ollitic ironstone, the worst is the river mouth delta sand shoal, in which the ore reserve is small (only 4.2%) and ore is poor (TFe27-28) . The precursor of the oolites girdles is colloid deposits in sea water, under the condition of high energy water, the ferrugenous materials around the debris or the former colloid segration of micrograined authigenous ferro-minerals will rotate and deposite and form the girdles of ironstone oolites. Under this condition there are muclei girdles in ironstone oolites, but some oolites without nuclei only with girdles. When the sea water only with a lower energy, the gel cumularspharolith without nucleus and without girdles may be deposited.
There are 7 minerogenetic districts of middle Devonian, the important ones are the I ,II , III and IV .. and of late Devonian, V, VI, and VII. Generally, there are 2-3 girdles in one oolite, but sometimes the number can as large as 20 and as small as one , the later may be called the pseudoolites. Sometimes an oolite is a gel cumularspharolith without girdles and without nucleus and sometimes there are many girdles in oolites but without nucleus. Composition of the girdles of oolites and gel cumularspharolithes are automorphic crystals of micrograined hematite, chlorites, siderites or the mixture of the three minerals with some clay minerals (mainly is illite) , minute collphane. The nuclei are made of quartz debris in general. The matrix between oolites are made of automorphic crystal micrograined ferruginous minerals, clay minerals, minute collphane or their clastes and quartz clastes. Oolites, pseudoolites, cumularspharolithes are round, ellipsoidal in shape, 0.2-0.8mm in diameter, and all of them are in the same size. The content of oolitic ironstone TFe is 30-40% generally with the range of 27-28% to 40-46%. In China, the best sedimentary environment of Devonian oolitic ironstone is the region nearby the closed shallow water lagoon , where reserved 60% of total Devonian ollitic ironstone, the worst is the river mouth delta sand shoal, in which the ore reserve is small (only 4.2%) and ore is poor (TFe27-28) . The precursor of the oolites girdles is colloid deposits in sea water, under the condition of high energy water, the ferrugenous materials around the debris or the former colloid segration of micrograined authigenous ferro-minerals will rotate and deposite and form the girdles of ironstone oolites. Under this condition there are muclei girdles in ironstone oolites, but some oolites without nuclei only with girdles. When the sea water only with a lower energy, the gel cumularspharolith without nucleus and without girdles may be deposited.
1993, 11(1): 111-120.
Abstract:
Clay mineralogy of the sediments deposited since the Pleistocene in the Mariana Trough and the West Philippine Basin was investigated by means of X-ray diffractometry and chemical analysis, based on three sediment cores (61KL, 57KL, 85KL) collected during the "SONNE"Cruise 57 in 1988. Predominant, well-cyrstallized smectite, with certain amount of Fe Mg chlorite, small amount of illite and no kaolinite, were identified in the sediments of the Mariana Trough (61KL, 57KL). Smectite and Fe Mg chlorite are authigenic in origin and were mainly formed by submarine alteration of basic volcanic material in the Trough, whereas illite is detriral in origin and was mainly derived from the continents west of the Philippine Sea. In the sediments of the West Philippine Basin (85KL), however, illite is predominant, followed by certain amount of poorly-crystallized smectite, small amount of normal chlorite and kaolinite. These minerals are chiefly detrital in origin and were mostly derived from the continents west and northwest of the Philippine Sea, except for smectite which may be mostly derived from the alteration of basic volcanic material on the Palau-Kyushu Ridge east of the basin, but at least small part of the smectite may probably be derived from the nonvolcanic rocks on the land. The main factors affecting the associations and distributions of clay minerals in the Mariana Trough and the West Philippine Basin were discussed. The volcanic activity is the most important factor controlling the clay mineral associations and distributions of the two basins. Material sources also play an important roll. The variations in chemical characteristics of clay minerals found in the Mariana Trough may reflect the influence of submarine hydrothermal activities possibly present in this basin. The changes in paleoclimate is an important factor controlling the clay mineral distributions, but in the Mariana Trough such an influence is seriously masked by the frequent volcanic activities.
Clay mineralogy of the sediments deposited since the Pleistocene in the Mariana Trough and the West Philippine Basin was investigated by means of X-ray diffractometry and chemical analysis, based on three sediment cores (61KL, 57KL, 85KL) collected during the "SONNE"Cruise 57 in 1988. Predominant, well-cyrstallized smectite, with certain amount of Fe Mg chlorite, small amount of illite and no kaolinite, were identified in the sediments of the Mariana Trough (61KL, 57KL). Smectite and Fe Mg chlorite are authigenic in origin and were mainly formed by submarine alteration of basic volcanic material in the Trough, whereas illite is detriral in origin and was mainly derived from the continents west of the Philippine Sea. In the sediments of the West Philippine Basin (85KL), however, illite is predominant, followed by certain amount of poorly-crystallized smectite, small amount of normal chlorite and kaolinite. These minerals are chiefly detrital in origin and were mostly derived from the continents west and northwest of the Philippine Sea, except for smectite which may be mostly derived from the alteration of basic volcanic material on the Palau-Kyushu Ridge east of the basin, but at least small part of the smectite may probably be derived from the nonvolcanic rocks on the land. The main factors affecting the associations and distributions of clay minerals in the Mariana Trough and the West Philippine Basin were discussed. The volcanic activity is the most important factor controlling the clay mineral associations and distributions of the two basins. Material sources also play an important roll. The variations in chemical characteristics of clay minerals found in the Mariana Trough may reflect the influence of submarine hydrothermal activities possibly present in this basin. The changes in paleoclimate is an important factor controlling the clay mineral distributions, but in the Mariana Trough such an influence is seriously masked by the frequent volcanic activities.
1993, 11(1): 128-135.
Abstract:
This paper reports the sedimentation rate determined by the 210Pb age dating based on the cores sampled from 10 stations in Liaodong Bay. Sampling was taken by using of core sampler in the central area and heavy-bore gravity core sampler and natural profile sampling in shallow water area and tideflat. More samples of upper part and less of the lower were analysed and determined, variation of 210Pb activity with depth, sedimentation rates and sedimentation flux of every station were listed, the result shows that except B841 station, the distribution of 210Pb activity decrease exponentially with depth, indicating that both of the sedimentation rate and processe were in relative stable period in recent 100 years. The distribution of sedimentation rate and flux reveals that the highest value of sedimentation rate is in the bay tip and decrease with increasing water depth southwestward, reaches its lowest value in B73 area and then get a slightly rebound. This pattern is contributed to the marine dynamics, geomorphological form, especially the difference of sediment input. The water-sand of Liaodong Bay tip stream system mainly deposited in the north area of B73 stati n. But in the south area of B73 station, water-sand is multiplly controlled by Luanhe River, Haihe River, especially the Yellow River, except for the water-sand that flows along the coast of Liaohe River. In the B386 station outside of Liaohe estuary, the distribution of 210Pb shows two decrease periods, the first is from the depth of 0-29cm and the second is under 29cm. Mereover, the sedimentation rate of the early period (0.71cm/ a) is greater than that of modern (0.54cm/ a), indicating that a sedimentation event had been taken place in this area. Based on the sedimentation flux analysis of the first line segment of 210Pb decay curve, it is calculated out that the first turn point, i.e., when the sedimentation event took place, was occurred during the years 1900-1910. This time period is conincided with one of the history case of Liaohe River. In the Shuangtaizihe Riverthat situates in the lower part of Liaohe River, there had been done artificial branch stream in late nineteenth century, let to the cut down of runoff and sand input to sea of Liaohe river mouth at Yingkou. The reducing of material sources of Liaohe river resulted in the decrease of modern sedimentation rate of Liaohe Bay. The 210Pb distribution curve of B386 proved the influence on the modern sedimentation rate by human activityes. The above mentioned study are rather important to the research of marine sedimentology, shallow sea exploitation, environmental background and pollution history.
This paper reports the sedimentation rate determined by the 210Pb age dating based on the cores sampled from 10 stations in Liaodong Bay. Sampling was taken by using of core sampler in the central area and heavy-bore gravity core sampler and natural profile sampling in shallow water area and tideflat. More samples of upper part and less of the lower were analysed and determined, variation of 210Pb activity with depth, sedimentation rates and sedimentation flux of every station were listed, the result shows that except B841 station, the distribution of 210Pb activity decrease exponentially with depth, indicating that both of the sedimentation rate and processe were in relative stable period in recent 100 years. The distribution of sedimentation rate and flux reveals that the highest value of sedimentation rate is in the bay tip and decrease with increasing water depth southwestward, reaches its lowest value in B73 area and then get a slightly rebound. This pattern is contributed to the marine dynamics, geomorphological form, especially the difference of sediment input. The water-sand of Liaodong Bay tip stream system mainly deposited in the north area of B73 stati n. But in the south area of B73 station, water-sand is multiplly controlled by Luanhe River, Haihe River, especially the Yellow River, except for the water-sand that flows along the coast of Liaohe River. In the B386 station outside of Liaohe estuary, the distribution of 210Pb shows two decrease periods, the first is from the depth of 0-29cm and the second is under 29cm. Mereover, the sedimentation rate of the early period (0.71cm/ a) is greater than that of modern (0.54cm/ a), indicating that a sedimentation event had been taken place in this area. Based on the sedimentation flux analysis of the first line segment of 210Pb decay curve, it is calculated out that the first turn point, i.e., when the sedimentation event took place, was occurred during the years 1900-1910. This time period is conincided with one of the history case of Liaohe River. In the Shuangtaizihe Riverthat situates in the lower part of Liaohe River, there had been done artificial branch stream in late nineteenth century, let to the cut down of runoff and sand input to sea of Liaohe river mouth at Yingkou. The reducing of material sources of Liaohe river resulted in the decrease of modern sedimentation rate of Liaohe Bay. The 210Pb distribution curve of B386 proved the influence on the modern sedimentation rate by human activityes. The above mentioned study are rather important to the research of marine sedimentology, shallow sea exploitation, environmental background and pollution history.
1993, 11(1): 12-22.
Abstract:
Current- meter data collected over the past 20 years has revealed the existence of currents flowing alternatively up and down most submarine canyons and other submarine valleys. These currents are attributed to internal weaves that are subsurface waves between layers of different density or within layers where vertical density gradients are present. An important kind of internal wave is that which has a period equal to the semidiurnal or diurnal tide and referred to as an internal tied. Velocities of bidirectional deep-water currents range from 20-50 cm / sec. Such currents can move sediment up to fine sand and form a lot of ripples at depths of several thousand meters. Nevertheless, internal-tied deposits have not been recognized in the ancient rock record. Recently, the authors identified evidence for internal tides in an upped Middle Ordovician deep-water, submarine channel-fill deposit in Fincastle area, Virginia Appalachians, USA. During late Middle Ordovician time, the Fincastle area was located on the southeastern slope of a foreland basin. There was a series of submarine channels that were oriented southeast-northwest in the paleoslope. The channel-fill deposits are dominantly various kind of gravity flow deposits, showing an up- ward fining and thinning trend. The internal-tide deposits cap the up-fining sequence. Flute casts on the bottom turbidite beds and ripple cross laminations defining the C- division of Bouma sequences yield paleocurrent directions towards NW325-330. A calculated paleowater depth are more than 204m. Two internal-tide facies are recoginzed. 1. Bidirectionnal, cross-laminated, very fine-grained sandstone facies. This facies is composed mainly of very fine-grained, sublithic wackes and locally siltstones. Interbed-ded with this facies are dark shales and thin turbidite beds. This facies is characterized by well-developed, bidirectional ripple cross laminations that display high-frequency alternations of paleocurret azimuths, the paleocurrent directions are towards SSE and NNW and these directions are parallel to the submarine channel axes and correspond with up-and down-channel directions. A single bed of internal-tide deposit displays symmetrical or normal grading. The characteristics described above indicate that this facies cannot represent either turbidty-current or contour-current deposits. This facies is attributed instead to internal tides. Opposing paleocurrent modes may reflect either diurnal or semidiurnal tides. Grain-size variations with the layers of this facies record different maximum current velocities possibly related to Neap-Spring tidal cycles. 2. Unidireetiuual, Cross-bedded and eross-laminated medium- to fine-grained sandstone facies. This facies is composed of medium- to fine-grained lithic wacke and displays symmetrical grading. Two types of cross stratification were indentified. The first consists of tabular cross bedding and is developed in the middle of a bed. Its grain size is mainly medium-grained sandstone. The second stratification type consists of climbing ripple laminations and lies under or upon the tabular Cross bedding. It is developed in mainly fine-to very fine-grained sandstone. The foresets of two types of cross stratification trend towards the SSE. Obviously, this facies resulted from currents directed up the channel axes. Under conditions in which a high-energy- long-period internal wave is superimposed on an internal tied, a dominant up-channel and a subordinate down-channel current are produced. This facies is attributed to such a superimposed current.
Current- meter data collected over the past 20 years has revealed the existence of currents flowing alternatively up and down most submarine canyons and other submarine valleys. These currents are attributed to internal weaves that are subsurface waves between layers of different density or within layers where vertical density gradients are present. An important kind of internal wave is that which has a period equal to the semidiurnal or diurnal tide and referred to as an internal tied. Velocities of bidirectional deep-water currents range from 20-50 cm / sec. Such currents can move sediment up to fine sand and form a lot of ripples at depths of several thousand meters. Nevertheless, internal-tied deposits have not been recognized in the ancient rock record. Recently, the authors identified evidence for internal tides in an upped Middle Ordovician deep-water, submarine channel-fill deposit in Fincastle area, Virginia Appalachians, USA. During late Middle Ordovician time, the Fincastle area was located on the southeastern slope of a foreland basin. There was a series of submarine channels that were oriented southeast-northwest in the paleoslope. The channel-fill deposits are dominantly various kind of gravity flow deposits, showing an up- ward fining and thinning trend. The internal-tide deposits cap the up-fining sequence. Flute casts on the bottom turbidite beds and ripple cross laminations defining the C- division of Bouma sequences yield paleocurrent directions towards NW325-330. A calculated paleowater depth are more than 204m. Two internal-tide facies are recoginzed. 1. Bidirectionnal, cross-laminated, very fine-grained sandstone facies. This facies is composed mainly of very fine-grained, sublithic wackes and locally siltstones. Interbed-ded with this facies are dark shales and thin turbidite beds. This facies is characterized by well-developed, bidirectional ripple cross laminations that display high-frequency alternations of paleocurret azimuths, the paleocurrent directions are towards SSE and NNW and these directions are parallel to the submarine channel axes and correspond with up-and down-channel directions. A single bed of internal-tide deposit displays symmetrical or normal grading. The characteristics described above indicate that this facies cannot represent either turbidty-current or contour-current deposits. This facies is attributed instead to internal tides. Opposing paleocurrent modes may reflect either diurnal or semidiurnal tides. Grain-size variations with the layers of this facies record different maximum current velocities possibly related to Neap-Spring tidal cycles. 2. Unidireetiuual, Cross-bedded and eross-laminated medium- to fine-grained sandstone facies. This facies is composed of medium- to fine-grained lithic wacke and displays symmetrical grading. Two types of cross stratification were indentified. The first consists of tabular cross bedding and is developed in the middle of a bed. Its grain size is mainly medium-grained sandstone. The second stratification type consists of climbing ripple laminations and lies under or upon the tabular Cross bedding. It is developed in mainly fine-to very fine-grained sandstone. The foresets of two types of cross stratification trend towards the SSE. Obviously, this facies resulted from currents directed up the channel axes. Under conditions in which a high-energy- long-period internal wave is superimposed on an internal tied, a dominant up-channel and a subordinate down-channel current are produced. This facies is attributed to such a superimposed current.
1993, 11(1): 32-40.
Abstract:
The Yinmin Formation is a unit of the Middle Proterozoic Kunyang Group distributed in Yunnan and Sichuan provinces, and is considered to be the as source bed of the wellknown Dongchuan type copper deposits. It is lithologically composed of breccia and or conglomerate, sandstone, siltstone, slate, and some dolomite at the upper part. The well-developed arkose and the distinctive purple colour reveals that the Yinmin Formation is a continental red bed which was formed in rift environment, and was the lowest unit of a transgressive series of rift sedimentation. Different kinds of breccia (and conglomerate) are developed in the Yinmin Formation which is. a special feature reflecting the rift background and later structural deformation. The present paper gives a preliminary classification of these breccia and describes some of them, with an emphasis on the process of formation of the syngenetic breccia. It is concluded that the Yinmin Formation as a whole is of terrestrial facies but not a marine facies nor a flysch.
The Yinmin Formation is a unit of the Middle Proterozoic Kunyang Group distributed in Yunnan and Sichuan provinces, and is considered to be the as source bed of the wellknown Dongchuan type copper deposits. It is lithologically composed of breccia and or conglomerate, sandstone, siltstone, slate, and some dolomite at the upper part. The well-developed arkose and the distinctive purple colour reveals that the Yinmin Formation is a continental red bed which was formed in rift environment, and was the lowest unit of a transgressive series of rift sedimentation. Different kinds of breccia (and conglomerate) are developed in the Yinmin Formation which is. a special feature reflecting the rift background and later structural deformation. The present paper gives a preliminary classification of these breccia and describes some of them, with an emphasis on the process of formation of the syngenetic breccia. It is concluded that the Yinmin Formation as a whole is of terrestrial facies but not a marine facies nor a flysch.
1993, 11(1): 47-55.
Abstract:
Diagenesis in the lower Triassic Qinglong formation of Southern Jiangsu are very complex and can be divived into nine kinds: micritization, deep- water cementation in the sea floor, shallow-water comentation, dolomitization, compaction and pressolution, dissolution, neomorphism, pyritization and silicification, structural fissure. Among those, micritization often formed micrite envelope on grain surface in shallow-water areas, which can prevent early-stage dissolution and protect casting pores formed by the dissolution. Deep-water submarine cementation occurred in the slope-basin areas and generally formed nodules or hard ground during no sedimentation. Shallow-water cementation can be clearly distinguished into three periods: 1 .Forming of fibrous, dog-toothed, or foliaceous cements, which reduced 5-10% of original pores; 2.Forming of equigranular cements decresed about 20-30% original pores; 3.The Forming of grain mosaic-like sparry cements, which were clearly uncomformable with the first and the second cements and reduced pores about 5%. Four kinds of the dolomitization are recognised: 1.Dolomites formed by penecontemporaneous dolomitization are usually intergrowthed with gypsum; 2.Mixed water dolomitization occured in the shallow- water areas, its result are euhedral to hemieuhedral dolomite rhombsthat distribute in dissolved pores of intraclast ooide coments, or matrix of lime wackestone and packstone; 3.Dolomites caused by deeply buried pressolution occurred in microstylolitic groups and clay bands or nearby stylolites; 4.Epigenetic dolomitization controlled by the structure commonly distribute along faults and the contact of dolomite surface with wall rocks is transitional or abrupt. Compaction and pressolution ordinaryly made rock porosity reduce greatly, but accompanying pressolved dolomilization and late dissolution, porosity and permeability could be increased. There are mainly three periods of dissolution in the areas discussed, the first occurred in platform shoal beach facies and created a lot of dissolved pores in the intergrains and intragrains; the second formed in buried diagenetic stages and were effective reservior spaces for the most part and were frequently filled with oil, gas and asphalt; the third dissolution happened in supergene stages and was majorly on recent or ancient erosional surfaces. Crystal Overgrowth that caused by neomorphism generally reduce a great deal of pores. The silicification was formed in supergene stages and occurred universally, especially in the slope-basin facies. Besides the increasing of porosity, more importantly, structural fissures raised permeability. Studying results showed: orginal pores influenced by the diagenesis changed greatly, in the shallow-water areas rapid drop of original pores was principally influenced by the cementation, but in the deep-water slope and basin the decrease of pores was chiefly affected by the compaction and pressolution. Besides, according to test data two potential reservior rocks in carbonate rocks of Qinglong formation are discoverd: one is lime grainstone of shoal beach facies in southeast districts and its porosity is 0.27 to 4.30% and permeability is 0.01 to 0.51 × 10-3μm2; another is nodular limestone and calcirudites of slope-basin facies in the western district and its porrosity is 1.31 to 1.98% and permeability 0.41 to 0.53 × 10-3μm2.
Diagenesis in the lower Triassic Qinglong formation of Southern Jiangsu are very complex and can be divived into nine kinds: micritization, deep- water cementation in the sea floor, shallow-water comentation, dolomitization, compaction and pressolution, dissolution, neomorphism, pyritization and silicification, structural fissure. Among those, micritization often formed micrite envelope on grain surface in shallow-water areas, which can prevent early-stage dissolution and protect casting pores formed by the dissolution. Deep-water submarine cementation occurred in the slope-basin areas and generally formed nodules or hard ground during no sedimentation. Shallow-water cementation can be clearly distinguished into three periods: 1 .Forming of fibrous, dog-toothed, or foliaceous cements, which reduced 5-10% of original pores; 2.Forming of equigranular cements decresed about 20-30% original pores; 3.The Forming of grain mosaic-like sparry cements, which were clearly uncomformable with the first and the second cements and reduced pores about 5%. Four kinds of the dolomitization are recognised: 1.Dolomites formed by penecontemporaneous dolomitization are usually intergrowthed with gypsum; 2.Mixed water dolomitization occured in the shallow- water areas, its result are euhedral to hemieuhedral dolomite rhombsthat distribute in dissolved pores of intraclast ooide coments, or matrix of lime wackestone and packstone; 3.Dolomites caused by deeply buried pressolution occurred in microstylolitic groups and clay bands or nearby stylolites; 4.Epigenetic dolomitization controlled by the structure commonly distribute along faults and the contact of dolomite surface with wall rocks is transitional or abrupt. Compaction and pressolution ordinaryly made rock porosity reduce greatly, but accompanying pressolved dolomilization and late dissolution, porosity and permeability could be increased. There are mainly three periods of dissolution in the areas discussed, the first occurred in platform shoal beach facies and created a lot of dissolved pores in the intergrains and intragrains; the second formed in buried diagenetic stages and were effective reservior spaces for the most part and were frequently filled with oil, gas and asphalt; the third dissolution happened in supergene stages and was majorly on recent or ancient erosional surfaces. Crystal Overgrowth that caused by neomorphism generally reduce a great deal of pores. The silicification was formed in supergene stages and occurred universally, especially in the slope-basin facies. Besides the increasing of porosity, more importantly, structural fissures raised permeability. Studying results showed: orginal pores influenced by the diagenesis changed greatly, in the shallow-water areas rapid drop of original pores was principally influenced by the cementation, but in the deep-water slope and basin the decrease of pores was chiefly affected by the compaction and pressolution. Besides, according to test data two potential reservior rocks in carbonate rocks of Qinglong formation are discoverd: one is lime grainstone of shoal beach facies in southeast districts and its porosity is 0.27 to 4.30% and permeability is 0.01 to 0.51 × 10-3μm2; another is nodular limestone and calcirudites of slope-basin facies in the western district and its porrosity is 1.31 to 1.98% and permeability 0.41 to 0.53 × 10-3μm2.
1993, 11(1): 65-74.
Abstract:
The Late Palaeozoic coalfield of Jiyu, Chezhoushan and Kaiping areas of eastern Hebei, situates in the east of North- China Platform. In recent years, the authors have discovered 3- 7 layers of pyroclastic intercalations at the bottom of coal seam No 12, the top and the bottom of coal seam No.9 and No.8 and the bottom of coal seam No.6. These rocks mainly consist of breccia- bearing andesitic ignimbrite, breccia-bearing andesitic debris tuff, andesitic crystal-debris tuff, crystal tuff, tuffite, tuffaceous sandstone, tuffaceous siltstone and tuffaceous limestone etc. By analyzing grain-size and projecting the grain-size parameters into Fisher's (1982) δp-Mdp dispersed diagrams and Passaga's (1957) C-M diagram, we found two samples fell into volcanic-ash flow area, the rest samples all fell into volcanic-ash descesion area and the grain- sizes getting finer and finer from northwest (Jiyu coalfield) to southeast (Kaiping coalfield) . By the petrochemical analysis and conversion of petrochemical parameters, it is found that all of these pyroclastic rock samples fell into igneous rock area of Niggli's diagram and and esite area of Church's diagram. The determine result of oxygen isotope of the pyroclastic samples is basically similar to the study result made by Faure ( 1983) and the determination data made by Morrison ( 1985) on British Triassic volcanic rocks, it shows that the original materials came from eruption of andesite. K-Ar age dating of volcanic breccia and tuffaceous interstitial materials suggest that both of them were not formed by denudation, transportation and re-precipitation of ancient andesite, but formed in Permian period. According to the grain-size distribution feature and vertical as well as herizontal correltion of strata profile of these three coalfields, the volcanic activities can be divided into three eruption stages including seven eruption times, the transportation direction of the volcanic materials (ashes) was from northwest to southeast. In the first stage, the effusive eruption may be taken as the dominant form, the scattered area of volcanic ashes was small and merely covered Jiyu and Chezhoushan coal fields; In the second and the third stages, the explosive eruption may be taken as the dominat form, the covered area of volcanic ashes was wider and transported far to Kaiping coalfield. This study also provided an important basis for the division and correlation of strata and coal seams of this area as well as for the study of tectonic activity and volcano-catatrophic events of plate inner basin of North China in Late Palaeozoic era.
The Late Palaeozoic coalfield of Jiyu, Chezhoushan and Kaiping areas of eastern Hebei, situates in the east of North- China Platform. In recent years, the authors have discovered 3- 7 layers of pyroclastic intercalations at the bottom of coal seam No 12, the top and the bottom of coal seam No.9 and No.8 and the bottom of coal seam No.6. These rocks mainly consist of breccia- bearing andesitic ignimbrite, breccia-bearing andesitic debris tuff, andesitic crystal-debris tuff, crystal tuff, tuffite, tuffaceous sandstone, tuffaceous siltstone and tuffaceous limestone etc. By analyzing grain-size and projecting the grain-size parameters into Fisher's (1982) δp-Mdp dispersed diagrams and Passaga's (1957) C-M diagram, we found two samples fell into volcanic-ash flow area, the rest samples all fell into volcanic-ash descesion area and the grain- sizes getting finer and finer from northwest (Jiyu coalfield) to southeast (Kaiping coalfield) . By the petrochemical analysis and conversion of petrochemical parameters, it is found that all of these pyroclastic rock samples fell into igneous rock area of Niggli's diagram and and esite area of Church's diagram. The determine result of oxygen isotope of the pyroclastic samples is basically similar to the study result made by Faure ( 1983) and the determination data made by Morrison ( 1985) on British Triassic volcanic rocks, it shows that the original materials came from eruption of andesite. K-Ar age dating of volcanic breccia and tuffaceous interstitial materials suggest that both of them were not formed by denudation, transportation and re-precipitation of ancient andesite, but formed in Permian period. According to the grain-size distribution feature and vertical as well as herizontal correltion of strata profile of these three coalfields, the volcanic activities can be divided into three eruption stages including seven eruption times, the transportation direction of the volcanic materials (ashes) was from northwest to southeast. In the first stage, the effusive eruption may be taken as the dominant form, the scattered area of volcanic ashes was small and merely covered Jiyu and Chezhoushan coal fields; In the second and the third stages, the explosive eruption may be taken as the dominat form, the covered area of volcanic ashes was wider and transported far to Kaiping coalfield. This study also provided an important basis for the division and correlation of strata and coal seams of this area as well as for the study of tectonic activity and volcano-catatrophic events of plate inner basin of North China in Late Palaeozoic era.
1993, 11(1): 84-92.
Abstract:
The phosphorites of Doushantuo Formation of Sinian System are mainly distributed in the Xingshenbao, Jinxiang and Yichang prefectures of Western Hubei Province. There are two main industrial ore beds, i. e., Ph1 and Ph2. According to the characteristics of texture and structure as well as material components of phosphorites, on the sedimentary section we've divided the ore bed into argillaceous striped phosphorite ( I ), argillacecus onyx one (II). dolomitic striped one (III) and compact block one (IV) from the bottom to the top. They are naturally piled up together and form the I - II -III-IV sequences in macro-structure and the different textures of phosphorites are also regularly and naturally piled up in the microcosmic sequences, gel-phosphorite (A), cumularspharolith one (B) and shelly granular one (C) from lower to upper and they form an A-B-C microcosmic sequence. We've sumed up characteristics about the macroscopic and microcosmic sequences and researched the inner link among them in the paper and there is also a inner link between the phosphorus granule type and matrix or cement in the microcosmic sequence. On the basis of the developmental degree of the sedimentary sequence of phosphorite we've divided 3 sequential types of integrated and incomplete as well as no-order ones and sumed up the relationship between the sequential type and industrial tenor of the phosphorous. The characteristed sedimentary sequence of phosphorite exists universally but owing to the influence of many factors such as palaeogeography. sedimentary circumstance and microorganism activity etc. , the integrity and developmental degree of phosphorite is different from each other in different mineral areas. The researchs indicate that the macroscopic sequences are obviously controlled by the sedimentary circumstance and palaeogeography, for example, in the palaeogeographic unit of shelf back-ground from the Western Hubei to the Middle Guizhou provinces the incomplete- type sequence has been formed in the deeper water basin facies, but no-order-type formed in the shallow water higher energy zone of upwarded district, the intergraded-type did in the clinoform zone between the above two and it is the best district to pile up the main industrial mineral body. The microcosmic sequence is controlled by the microorganism activities and is a product of the microorganism periodical activities in the same circumstance. The phosphorite sequence not only has a theoretical significance to research mineralization, enrich regular patterns of mineral and cause of formation of mineral deposit of phosphorite, but also has a directive one to prospect and explore mineral as well as evaluate mineral deposits of phosphorits.
The phosphorites of Doushantuo Formation of Sinian System are mainly distributed in the Xingshenbao, Jinxiang and Yichang prefectures of Western Hubei Province. There are two main industrial ore beds, i. e., Ph1 and Ph2. According to the characteristics of texture and structure as well as material components of phosphorites, on the sedimentary section we've divided the ore bed into argillaceous striped phosphorite ( I ), argillacecus onyx one (II). dolomitic striped one (III) and compact block one (IV) from the bottom to the top. They are naturally piled up together and form the I - II -III-IV sequences in macro-structure and the different textures of phosphorites are also regularly and naturally piled up in the microcosmic sequences, gel-phosphorite (A), cumularspharolith one (B) and shelly granular one (C) from lower to upper and they form an A-B-C microcosmic sequence. We've sumed up characteristics about the macroscopic and microcosmic sequences and researched the inner link among them in the paper and there is also a inner link between the phosphorus granule type and matrix or cement in the microcosmic sequence. On the basis of the developmental degree of the sedimentary sequence of phosphorite we've divided 3 sequential types of integrated and incomplete as well as no-order ones and sumed up the relationship between the sequential type and industrial tenor of the phosphorous. The characteristed sedimentary sequence of phosphorite exists universally but owing to the influence of many factors such as palaeogeography. sedimentary circumstance and microorganism activity etc. , the integrity and developmental degree of phosphorite is different from each other in different mineral areas. The researchs indicate that the macroscopic sequences are obviously controlled by the sedimentary circumstance and palaeogeography, for example, in the palaeogeographic unit of shelf back-ground from the Western Hubei to the Middle Guizhou provinces the incomplete- type sequence has been formed in the deeper water basin facies, but no-order-type formed in the shallow water higher energy zone of upwarded district, the intergraded-type did in the clinoform zone between the above two and it is the best district to pile up the main industrial mineral body. The microcosmic sequence is controlled by the microorganism activities and is a product of the microorganism periodical activities in the same circumstance. The phosphorite sequence not only has a theoretical significance to research mineralization, enrich regular patterns of mineral and cause of formation of mineral deposit of phosphorite, but also has a directive one to prospect and explore mineral as well as evaluate mineral deposits of phosphorits.
1993, 11(1): 103-110.
Abstract:
The small outcrop, a part of Guilin Formation, is about 30m thick and represents a deposits from subtidal lagoon to tidal flat in the carbonate platform. Its fossils are characterized by Amphipora sp. (or Paramphipora sp.), Tenticospirifer and the fossils of its equivalent beds are marked by Ozarkodina poster, Icrious alternants alternatus, 1. a. helmsi , indicating a late Frasnian age. Microfacies analysis revealed that limestone bearing Amphipora sp. in the upper member of Guilin Formation forms the cyclic deposits. These cycles are mainly composed of three microfacies. 1. Gastropod wackestone 2. Twing-like Amphipora and spherical stromatoporoid packstone 3. Spherical, hemispherical and irregular stromatoporoid packstone. Biofacies characteristics of the outcrop show three main fossil assemblages in each cycle: 1. Gastropod fossil assemblage 2. Amphipora, gastropod and brachiopod fossil assemblage 3. Spherical, hemispherical and irregular stromatoporoid assemblage. According to the observation in the field and under the microscope, Amphipora taphocoenosis in the study outcrop exhibit many allochthonos characters. The conclusion is that the subtide with slightly fluctuated water is best suited for Amphipora growth, and the completely restricted and euxinic lagoon is not beneficial to their growth and only fit to be accumulated instead.
The small outcrop, a part of Guilin Formation, is about 30m thick and represents a deposits from subtidal lagoon to tidal flat in the carbonate platform. Its fossils are characterized by Amphipora sp. (or Paramphipora sp.), Tenticospirifer and the fossils of its equivalent beds are marked by Ozarkodina poster, Icrious alternants alternatus, 1. a. helmsi , indicating a late Frasnian age. Microfacies analysis revealed that limestone bearing Amphipora sp. in the upper member of Guilin Formation forms the cyclic deposits. These cycles are mainly composed of three microfacies. 1. Gastropod wackestone 2. Twing-like Amphipora and spherical stromatoporoid packstone 3. Spherical, hemispherical and irregular stromatoporoid packstone. Biofacies characteristics of the outcrop show three main fossil assemblages in each cycle: 1. Gastropod fossil assemblage 2. Amphipora, gastropod and brachiopod fossil assemblage 3. Spherical, hemispherical and irregular stromatoporoid assemblage. According to the observation in the field and under the microscope, Amphipora taphocoenosis in the study outcrop exhibit many allochthonos characters. The conclusion is that the subtide with slightly fluctuated water is best suited for Amphipora growth, and the completely restricted and euxinic lagoon is not beneficial to their growth and only fit to be accumulated instead.
1993, 11(1): 121-127.
Abstract:
The study area is located at 7° -15 ° N, 13 ° 845 ' -153 ° 30 ' W, that is , at the northern edge of the radiolaria-rich zone in the Eastern Pacific Basin. To the east, it bordered with the Eastern Pacific Seamounts; to west, with the Clarion Transform Fault, and to South, with the Clipperton Transform Fault. Seafloor topography in this region mainly strikes NEE-SWW and is distributed in zonation. The relief appears high on the east and low on the west, steep on the north and gentle on the south. Seafloor sediments there chiefly include deep-sea siliceous clay, siliceous ooze, Si-bearing calcareous ooze, calcareous ooze and Ca-bearing sililceous ooze, among which siliceous ooze is most widely distributed, covering about 50% of the area. Based on fossil identification, palaeomagnetic measurement and 10Be determination of seafloor sediments in the Eastern Pacific Ocean, we come to conclude that these sediments are mainly of Quartemary age. Lower Miocene of the upper Tertiary is only locally exposed in southwestern part of the study area, whilst Oligocene is only sparsely seen at the northwestern sector. The identification of calcareous nanofossils and foraminifera in the seafloor sediments suggests a carbonate compensation depth (CCD) of 4, 800-4, 900m. Through studies of seafloor sediments in the Eastern Pacific Ocean, the author found that: 1) These sediments are mainly composed of minerals less than 0.063mm in grain size, such as illite, montmorillonite+mixed mineral layers, kaolinite, clayey green earth minerals, radiolaria and diatoms etc.. Their average grain size ( M1) ranges between 7. 49- 12. 21p and medial grain size (p50) between 7.11-9.44p, which indicates a fine silt and clay grade. The dispersion degree (δ1) is between 1.27-16.67. 2) Chemical composition of these sediments mainly include SiO2 , A12O3, Na2O, K2O, CaO and MgO among which SiO2 (48.55%) and A12O3(11.69%) are dominant, totalling up above 60%. The content and composition of dissoluble salts in the seafloor sediment of the study area is not only dependent on the composition of sediments but also closely related to CCD in the region. 3) pH values of the seafloor sediments in the area all exceed 7, thus indicating an alkaline nature. A diffusive double-electric films are usually developed on the soil-grain surface of sediments with such a feature, that turns those sediments into a dispersive state. 4) As seafloor sediments in the study area are characterized by such a -lay mineral assemblage with dominant illite and montmorillonite+mixed mineral layers and some kaolinte and green earth, their ion exchange volume is generally between 45.98-65.09me / 100g, which is larger than 10-40me / 100g of the illite and smaller than 80-150me /100g of the montmorillonite. Same as those of other marine sediments, these ions include Ca2+, Mg2+, K+ and Na+. 5) Because of their above-mentioned features, seafloor sediments in the study area hold a relatively high and changeable surface ratio values ranging between 93.81-157.48m2 / g, which again run intermediate compared with the surface ratio of montmorillonite clay ( 810m2/ g) and that of illite clay (67-100m2/g)
The study area is located at 7° -15 ° N, 13 ° 845 ' -153 ° 30 ' W, that is , at the northern edge of the radiolaria-rich zone in the Eastern Pacific Basin. To the east, it bordered with the Eastern Pacific Seamounts; to west, with the Clarion Transform Fault, and to South, with the Clipperton Transform Fault. Seafloor topography in this region mainly strikes NEE-SWW and is distributed in zonation. The relief appears high on the east and low on the west, steep on the north and gentle on the south. Seafloor sediments there chiefly include deep-sea siliceous clay, siliceous ooze, Si-bearing calcareous ooze, calcareous ooze and Ca-bearing sililceous ooze, among which siliceous ooze is most widely distributed, covering about 50% of the area. Based on fossil identification, palaeomagnetic measurement and 10Be determination of seafloor sediments in the Eastern Pacific Ocean, we come to conclude that these sediments are mainly of Quartemary age. Lower Miocene of the upper Tertiary is only locally exposed in southwestern part of the study area, whilst Oligocene is only sparsely seen at the northwestern sector. The identification of calcareous nanofossils and foraminifera in the seafloor sediments suggests a carbonate compensation depth (CCD) of 4, 800-4, 900m. Through studies of seafloor sediments in the Eastern Pacific Ocean, the author found that: 1) These sediments are mainly composed of minerals less than 0.063mm in grain size, such as illite, montmorillonite+mixed mineral layers, kaolinite, clayey green earth minerals, radiolaria and diatoms etc.. Their average grain size ( M1) ranges between 7. 49- 12. 21p and medial grain size (p50) between 7.11-9.44p, which indicates a fine silt and clay grade. The dispersion degree (δ1) is between 1.27-16.67. 2) Chemical composition of these sediments mainly include SiO2 , A12O3, Na2O, K2O, CaO and MgO among which SiO2 (48.55%) and A12O3(11.69%) are dominant, totalling up above 60%. The content and composition of dissoluble salts in the seafloor sediment of the study area is not only dependent on the composition of sediments but also closely related to CCD in the region. 3) pH values of the seafloor sediments in the area all exceed 7, thus indicating an alkaline nature. A diffusive double-electric films are usually developed on the soil-grain surface of sediments with such a feature, that turns those sediments into a dispersive state. 4) As seafloor sediments in the study area are characterized by such a -lay mineral assemblage with dominant illite and montmorillonite+mixed mineral layers and some kaolinte and green earth, their ion exchange volume is generally between 45.98-65.09me / 100g, which is larger than 10-40me / 100g of the illite and smaller than 80-150me /100g of the montmorillonite. Same as those of other marine sediments, these ions include Ca2+, Mg2+, K+ and Na+. 5) Because of their above-mentioned features, seafloor sediments in the study area hold a relatively high and changeable surface ratio values ranging between 93.81-157.48m2 / g, which again run intermediate compared with the surface ratio of montmorillonite clay ( 810m2/ g) and that of illite clay (67-100m2/g)
1993, 11(1): 136-146.
Abstract:
CaC03 content. existing form and iUuvial depth in loess strata are studied in this paper. In order tomake clear the relation between CaC03 content and climate, the author firstly classify CaC03 into fivetypes and their relation with climate are discussed as follows. (1) High fragmental CaC03 content indi-cater weak leaching and arid climate, low content indicates intense leaching and humid climaie. (2) IlluvialCaC03 is secondary CaC03that formed by leaching and illuviating, and the content of secondary CaC03 ishigher than 5%. The illuvial GaC03 is riot realiable for reconstructing the climate, but generally, low con-tent represents humid climate and high content arid climate. However, dense accumulation of CaC03 mayindicates humid climate. (3) ,Contemporaneous remnant CaC03 is the residu al of leaching that occuredduring the development of soil, the content of CaC03 is less than 5% and the less the content is，the moreliumid the climate. (4) Deuterogenic residual CaC03 (with the content less than 5%)is the remant ofleaching that look place during the development of the overlying soil, the abandance of CaC03 is low andcan not reflect the climate of the soil strata growth. (S) Evaporated CaC03 was the precipitates that desertposited at the top layer of soil during the intensive evaporate process, and its content represented the desertclimate with a mean annual rainfall less than 100mm. Loess and palaeosoil containing thin film and. stain but not concretions was developed under the climate。with mean annual rainfall less than 450mm, (continued on page 54)
CaC03 content. existing form and iUuvial depth in loess strata are studied in this paper. In order tomake clear the relation between CaC03 content and climate, the author firstly classify CaC03 into fivetypes and their relation with climate are discussed as follows. (1) High fragmental CaC03 content indi-cater weak leaching and arid climate, low content indicates intense leaching and humid climaie. (2) IlluvialCaC03 is secondary CaC03that formed by leaching and illuviating, and the content of secondary CaC03 ishigher than 5%. The illuvial GaC03 is riot realiable for reconstructing the climate, but generally, low con-tent represents humid climate and high content arid climate. However, dense accumulation of CaC03 mayindicates humid climate. (3) ,Contemporaneous remnant CaC03 is the residu al of leaching that occuredduring the development of soil, the content of CaC03 is less than 5% and the less the content is，the moreliumid the climate. (4) Deuterogenic residual CaC03 (with the content less than 5%)is the remant ofleaching that look place during the development of the overlying soil, the abandance of CaC03 is low andcan not reflect the climate of the soil strata growth. (S) Evaporated CaC03 was the precipitates that desertposited at the top layer of soil during the intensive evaporate process, and its content represented the desertclimate with a mean annual rainfall less than 100mm. Loess and palaeosoil containing thin film and. stain but not concretions was developed under the climate。with mean annual rainfall less than 450mm, (continued on page 54)
