1989 Vol. 7, No. 1
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Display Method:
1989, 7(1): 1-10.
Abstract:
The bauxite deposits in China can be divided into palaeoresidiuum bauxite deposits type (type Ⅰ) and laterite deposits type (type Ⅱ ) . The former can be diviede into six subtypes: Ia, alumina silicates rock palaeoresidiuum autochthonous residure bauxite deposit subtype; I b, carbonates rock palaeoresidiuum autochthonous accumulated bauxite deposit subtype; I c, the one of carbonate rock palacordsidiuum allogenically accumulate; I d, the one of carbonate rock palaeoresidiuum allogcnically sedimentary (lacustrine; I e, the one of palaeoresidiuum allogenically sedimentary (marine); I e, the one ofcarbonatcs rock palaeoresidiuum autochthonous accumulate (or sedimented) -the one or modern karst accumulate. 2. The minerals association of palaeoresidiuum bauxite deposit and laterite bauxite deposit of China are all the same, they are: alumina mincral+clay mincral+iron mineral+a small quantity titanic mineral and heavy mineral. The alumina mineral in type II is gibbsite, and in type I is diaspore, because the type I was prod-ucted in paloeozoic. and was dehydrated easy. The texture and structure of bauxite ores in type I . and type II such as clastic, pisolitic, oolitie, nodules (concretions) are the very same, therefore the type I and type n are all the product of latcritization in the palaeoresidiuum. According to the oxygen and hydrogen isotope constitute of the mineral composition in type I and type II and the mineral composition in the textures such as clastic, oolitic, pisolitic of the type I and type II, the δ18O‰ (SMOW) range from +5 to +20, δD‰ from -50 to -100.The data indicate that the clastic, oolitic, pisolitic bauxite ores are the product of weathering as well. 3. The laterite bauxite deposit (type II) and 60% of palaeoresidiuum bauxite deposit such as subtype I a, I b. I c are the lateritization weathering alumina material autochthonous residue. accumulated or allogencally accumulated occured under the atmosphere condition. 40% of palaeoresidiuum bauxite deposit such as subtype I d. Ic is the aluminal materials allogenically sedimented in lacustrine or marine which are the product of lateritization. Subtype I e is the karst accumulated under modern atmosphere condition which is from the subtype I bor I d.
The bauxite deposits in China can be divided into palaeoresidiuum bauxite deposits type (type Ⅰ) and laterite deposits type (type Ⅱ ) . The former can be diviede into six subtypes: Ia, alumina silicates rock palaeoresidiuum autochthonous residure bauxite deposit subtype; I b, carbonates rock palaeoresidiuum autochthonous accumulated bauxite deposit subtype; I c, the one of carbonate rock palacordsidiuum allogenically accumulate; I d, the one of carbonate rock palaeoresidiuum allogcnically sedimentary (lacustrine; I e, the one of palaeoresidiuum allogenically sedimentary (marine); I e, the one ofcarbonatcs rock palaeoresidiuum autochthonous accumulate (or sedimented) -the one or modern karst accumulate. 2. The minerals association of palaeoresidiuum bauxite deposit and laterite bauxite deposit of China are all the same, they are: alumina mincral+clay mincral+iron mineral+a small quantity titanic mineral and heavy mineral. The alumina mineral in type II is gibbsite, and in type I is diaspore, because the type I was prod-ucted in paloeozoic. and was dehydrated easy. The texture and structure of bauxite ores in type I . and type II such as clastic, pisolitic, oolitie, nodules (concretions) are the very same, therefore the type I and type n are all the product of latcritization in the palaeoresidiuum. According to the oxygen and hydrogen isotope constitute of the mineral composition in type I and type II and the mineral composition in the textures such as clastic, oolitic, pisolitic of the type I and type II, the δ18O‰ (SMOW) range from +5 to +20, δD‰ from -50 to -100.The data indicate that the clastic, oolitic, pisolitic bauxite ores are the product of weathering as well. 3. The laterite bauxite deposit (type II) and 60% of palaeoresidiuum bauxite deposit such as subtype I a, I b. I c are the lateritization weathering alumina material autochthonous residue. accumulated or allogencally accumulated occured under the atmosphere condition. 40% of palaeoresidiuum bauxite deposit such as subtype I d. Ic is the aluminal materials allogenically sedimented in lacustrine or marine which are the product of lateritization. Subtype I e is the karst accumulated under modern atmosphere condition which is from the subtype I bor I d.
1989, 7(1): 29-37.
Abstract:
The terrestrial oils of the Cretaceous and Tertiary from New Zealand have the special geochcmical characteristics, and the Quaternary oil is of unique singificance in the study of oil generation. Fifteen samples were collected from the Western Basin Province and Waiotapu high geothermal area in New Zealand, and the samples can be divided into three types: crude oils and condersates from producing oilfields; crude oils from non-commercial wells or coal exploration holes; and oil seepages. By the analysis of GC, carbon isotopes. GC-MS of saturates, it showed that the fifteen oils were formed in three types of conditions: 1. Oils formed in terrestrial marsh and shore-swamp environments, with great amount of plant input; the oils had the C29sterane predominance, the high pristane to phytane ratio and relatively light carbon isotopic composition. 2. Oils apparently biodegredated or water bleached, although the n-alkanes were destroyed, iso alkane are obvious and primarane is high; the characters of type 1 still remain. 3. Oils formed from the lacustrine sediments interlayered by volcanic ashes, with high thermal gradient and the anaerobic conditions, sulphur abundant medium. The oils are characteredc by C27+28sterane predominance, evennumbered carbon predominance and the groupes of double peaks. The content of Gammarane is relatively high and the composition of carbon isotope is light. The maturity of New Zealand oils is not high, especially the oil from the Quaternary high thermal area is low mature.
The terrestrial oils of the Cretaceous and Tertiary from New Zealand have the special geochcmical characteristics, and the Quaternary oil is of unique singificance in the study of oil generation. Fifteen samples were collected from the Western Basin Province and Waiotapu high geothermal area in New Zealand, and the samples can be divided into three types: crude oils and condersates from producing oilfields; crude oils from non-commercial wells or coal exploration holes; and oil seepages. By the analysis of GC, carbon isotopes. GC-MS of saturates, it showed that the fifteen oils were formed in three types of conditions: 1. Oils formed in terrestrial marsh and shore-swamp environments, with great amount of plant input; the oils had the C29sterane predominance, the high pristane to phytane ratio and relatively light carbon isotopic composition. 2. Oils apparently biodegredated or water bleached, although the n-alkanes were destroyed, iso alkane are obvious and primarane is high; the characters of type 1 still remain. 3. Oils formed from the lacustrine sediments interlayered by volcanic ashes, with high thermal gradient and the anaerobic conditions, sulphur abundant medium. The oils are characteredc by C27+28sterane predominance, evennumbered carbon predominance and the groupes of double peaks. The content of Gammarane is relatively high and the composition of carbon isotope is light. The maturity of New Zealand oils is not high, especially the oil from the Quaternary high thermal area is low mature.
1989, 7(1): 49-59.
Abstract:
The zonal trench of the Northern Tianshan was formed in the middle Devonian and devcioped into the one of the late Carboniferous. The middle Carboniferous filled in thcarcnch outcrops compictcly and ivpical's along the Duku highway, south of Dushanzi, Wusu. The lower pan is ophiolitc suite and the upper part is the Pvsch series of more than 2000 meters. The present paper laid the stress on the dcmonstratior of the cha-acterstics of the flysch suit in the section. The Flysch facics is composed of the rhythimitcs or dark grey green- grey black volcaniclastic rock of turbidity current origin, as well as contourites. The vertical sequence can be seperated into two part. The lower part is composed of the turbidite A, E sequence. A section, the middle to fine particles mainly, is 10-30cm thick, but E section is only several centimeters. The thickness and size of lower part have no obvious variation vernation; and its sedimentary environment can be attributed to the smooth portion of suprafan lobe in turbidite fan . The upper pan, except two successions of sequence which is thin-and fine upward, show the trend that thickcning- and coarsening - upward. This sequence represented the progradation forward of the mid-fan. As for the chemical composition of volcaniclastic turbidites SiO2amounts to 60-65%, K2O to 1.91-2.50%, Na2O to 2.65-3.84%, δ 3.3. So it can be assigned to the basalt-andesites. Eight ichnogenus were found in flysch facies: Chondrites furcatus; Cosmorhaphe sp.; phycosiphon incertum Fischer-Ooster; Hclminthopsis sp.; Zoophycos sp.; Nereites sp.; Neonereites uniserialis Seilachcr; Lophoctenium sp.; They are all attributed to Nereites ichnofacies relevent to the deep-sea turbidites.
The zonal trench of the Northern Tianshan was formed in the middle Devonian and devcioped into the one of the late Carboniferous. The middle Carboniferous filled in thcarcnch outcrops compictcly and ivpical's along the Duku highway, south of Dushanzi, Wusu. The lower pan is ophiolitc suite and the upper part is the Pvsch series of more than 2000 meters. The present paper laid the stress on the dcmonstratior of the cha-acterstics of the flysch suit in the section. The Flysch facics is composed of the rhythimitcs or dark grey green- grey black volcaniclastic rock of turbidity current origin, as well as contourites. The vertical sequence can be seperated into two part. The lower part is composed of the turbidite A, E sequence. A section, the middle to fine particles mainly, is 10-30cm thick, but E section is only several centimeters. The thickness and size of lower part have no obvious variation vernation; and its sedimentary environment can be attributed to the smooth portion of suprafan lobe in turbidite fan . The upper pan, except two successions of sequence which is thin-and fine upward, show the trend that thickcning- and coarsening - upward. This sequence represented the progradation forward of the mid-fan. As for the chemical composition of volcaniclastic turbidites SiO2amounts to 60-65%, K2O to 1.91-2.50%, Na2O to 2.65-3.84%, δ 3.3. So it can be assigned to the basalt-andesites. Eight ichnogenus were found in flysch facies: Chondrites furcatus; Cosmorhaphe sp.; phycosiphon incertum Fischer-Ooster; Hclminthopsis sp.; Zoophycos sp.; Nereites sp.; Neonereites uniserialis Seilachcr; Lophoctenium sp.; They are all attributed to Nereites ichnofacies relevent to the deep-sea turbidites.
1989, 7(1): 81-89.
Abstract:
The ore deposit occured in carbonate rocks located in an exocontact belt (O- 120m) of the L granite batholith (Fig. 1) .The deposit was hosted by argillaceous limestone of the Yingtang Formation, Middle Devonian.The L granite body with an area of 238km2has K-Ar age of 202-318Ma. U-Pb ages of pitchblende from the deposit are 65.0±0.6Ma, 59.2 ± 0.6Ma, 30.7 ± 0.6Ma.The time-gap between the age of granite and the time of ore deposition is large, which indicates there is not a direct relationship between the mineralization and intrusive activity of the L granite body. Sulfur isotopic compositions of 30 pyrites from the ores range from δ34S values of+0.8 to -39.81 per mil which are approximately similar to those of the host rocks (ranging from -8.05 to -20.49 per mil for pyrites (Table 2) . The 4 analyzed calcites from ores have δ13C values between -0.23 and -1.53 per mil (Table 4) . The 4 analyzed host rocks have δ13C values between +1.004 and -0.965 per mil.These data are very similar. U-Pb isotopic compositions of 3 K-feldspars from the granite, 3 galenas associated with pitchblende and 7 granitic rocks have been determined (Table 3, 5) .The calculative results suggest: (1) .All leads belong to an anomalous type low in radiogcnctic lcad. These data possess a good linear relation in 207Pb/ 204Pb-206Pb /204Pb plots (Fig.4), implying a genetic connection between the granite and the ore. (2) .Average loss of uranium in granitc has been 59.51% since the granite is formed, while average addition of uranium in granite near limestone has been 49.56%.It is an important uranium source for the mineralization. The δ18O values ( SMOW, 6 samples) of ore-forming fluid at 120°-281℃ in equilibrum with microcrystallinc quartzs and calcitcs range from -3.14 to+13.92 per mil (Table 6), which are higher than those of ancient meteoric water in the area.It may be due to the oxygen isotopic exchange between the meteoric water (δ13OH2o = -9~-10pcr mil) and limestone (δ18OH2o ≠ +12.68~+26.15 per mil) . There arc reasons to believe that in the ore constituents S, C were mainly derived from the host rocks (argillaceous limestone), and U, Pb mainly from the granite.The ore-forming fluid was dominated by meteoric water. It can be imagined that the surface water in the period of continental weathering and oxidation (Cretaceous) infiltrated downwards, leaching out large amounts of uranium from the granitic rocks to form infiltration solution. A part of uranium in solution was adsorpted by argillaceous limestones. The solution was heated at large depth and then moved upwards, during which it dissolved constantly uranium from the host rocks to form the deposit. Therefore, the 3701 uranium deposit is a stratabound one of the multi-source and later multi-superimposition of hydrothermal transformation.
The ore deposit occured in carbonate rocks located in an exocontact belt (O- 120m) of the L granite batholith (Fig. 1) .The deposit was hosted by argillaceous limestone of the Yingtang Formation, Middle Devonian.The L granite body with an area of 238km2has K-Ar age of 202-318Ma. U-Pb ages of pitchblende from the deposit are 65.0±0.6Ma, 59.2 ± 0.6Ma, 30.7 ± 0.6Ma.The time-gap between the age of granite and the time of ore deposition is large, which indicates there is not a direct relationship between the mineralization and intrusive activity of the L granite body. Sulfur isotopic compositions of 30 pyrites from the ores range from δ34S values of+0.8 to -39.81 per mil which are approximately similar to those of the host rocks (ranging from -8.05 to -20.49 per mil for pyrites (Table 2) . The 4 analyzed calcites from ores have δ13C values between -0.23 and -1.53 per mil (Table 4) . The 4 analyzed host rocks have δ13C values between +1.004 and -0.965 per mil.These data are very similar. U-Pb isotopic compositions of 3 K-feldspars from the granite, 3 galenas associated with pitchblende and 7 granitic rocks have been determined (Table 3, 5) .The calculative results suggest: (1) .All leads belong to an anomalous type low in radiogcnctic lcad. These data possess a good linear relation in 207Pb/ 204Pb-206Pb /204Pb plots (Fig.4), implying a genetic connection between the granite and the ore. (2) .Average loss of uranium in granitc has been 59.51% since the granite is formed, while average addition of uranium in granite near limestone has been 49.56%.It is an important uranium source for the mineralization. The δ18O values ( SMOW, 6 samples) of ore-forming fluid at 120°-281℃ in equilibrum with microcrystallinc quartzs and calcitcs range from -3.14 to+13.92 per mil (Table 6), which are higher than those of ancient meteoric water in the area.It may be due to the oxygen isotopic exchange between the meteoric water (δ13OH2o = -9~-10pcr mil) and limestone (δ18OH2o ≠ +12.68~+26.15 per mil) . There arc reasons to believe that in the ore constituents S, C were mainly derived from the host rocks (argillaceous limestone), and U, Pb mainly from the granite.The ore-forming fluid was dominated by meteoric water. It can be imagined that the surface water in the period of continental weathering and oxidation (Cretaceous) infiltrated downwards, leaching out large amounts of uranium from the granitic rocks to form infiltration solution. A part of uranium in solution was adsorpted by argillaceous limestones. The solution was heated at large depth and then moved upwards, during which it dissolved constantly uranium from the host rocks to form the deposit. Therefore, the 3701 uranium deposit is a stratabound one of the multi-source and later multi-superimposition of hydrothermal transformation.
1989, 7(1): 101-108.
Abstract:
This paper deals with the material source and process of formation of tonsteins mainly on the basis of distribution, occurrence, texture, structure, and material composition. Tonsteins of volcanic origin arc exceedingly widely distributed in our country. They were found in the Inner Mongolia, Shaanxi, Shanxi, Hcbei, Shandong in Northern China and wide areas of coal fields in Southwest China.Tonsteins are commonly developed in coal measures of Carboniferous-Permian and stable in horizon.They occur as thin beds less than 1m (some only 0.02 ± m.) in thickness but their thickness keep constant in thousands of km2, so they may be used as isochronous correlative horizons. The contact between the top and bottom surfaces of tonstein bed and coal is generally distinct and even, and has no indication of current scour.The bedding is not developed, and generally has massive structure.Tonstcins arc usually drak-brown in coal bed, because they contain organic carbon, but arc greyish white in coal-free bed. The mineral compositions are very simple.They are mainly composed of kaolinite and kalolinite-dickitc. Their textures are very complex and diverse, from cryptocrystalline to macrocrystalline vermicular crystals of kaolinite, and some intact pseudocrystals of feldspar are composed of microcrystalline kaolinite. The degree of order of kaolinites differs by X-ray diffraction analysis, and is generally proportional to the size of crystal. The degree of order of macrocrystal of kaolinite is high. The degree of order of cryprocrystalline kaolinite is low. The macrocrystalline kaolinite contains usually minor dickite. There are two cndothcrmic peaks at 590 and 670 on differential thermal curve. After heat treatment(550℃)the samples have still (00l)and (002)pcaks on X-ray diffraction spectrum, so the presence of dickite may be confirmed further. The content of crystal fragment of primary mineral is low, but is the main basis to analysis the source of material. The chemical compositions of tonsteins are quite simple too. They are mostly silica (45% ± ), alumina (35%± ), and water (13% ± ), total is 95% ± . The molecular ratio SiO2/ Al2O3of monomineralic tonstein is close to near 2. The contents of K2O, Na2O, CaO and MgO are lower.The trace elements more than 30 were determined by emission spectroscopy using an inductive coupled plasma (ICP). According to this result the contents of iron family elements (Fe, Ti, Mn, V, Cr, Ni, Co)are lower, but those of Th, U, B and Zr are higher. The ratio of Ti to Th is near to acid magmtic rock. Based on colour and textural features three typical tonsteins are common: 1. Light coloured crystallinoclast-bearing macrocrystalline tonstein. 2. Dark-bropwm, macrocrystallin tonstein 3. Brown-grey microcrystalline tonstein. The difference of tonstein from common shale and mudstone lies in that the former is widely distributed, thin, stable in horizon, and not developed in bedding. The main difference is that tonstein is exceedingly simple in material composition, the kaolinite contained absolutely predominates and contains a little dickite, the crystallinoclasts of primary mineral include hypothermal mineral assemblages, the Al2O3content is higher, the contents of K2O, Na2O, CaO and MgO are lower, the iron family elements contents are lower, and radioactive element content is higher. According to the above mentioned distribution, occurrence, texture, structure, particularly mineral and chemical compositions of tonsteins. the material originated from acid volcanic ashes. The tonsteins have important significance in event stratigraphy and greater economic value. However, at present for the tonstein there are little expoundings in sedimentary petrology, and almost no proper position, these deserving extra attention also.
This paper deals with the material source and process of formation of tonsteins mainly on the basis of distribution, occurrence, texture, structure, and material composition. Tonsteins of volcanic origin arc exceedingly widely distributed in our country. They were found in the Inner Mongolia, Shaanxi, Shanxi, Hcbei, Shandong in Northern China and wide areas of coal fields in Southwest China.Tonsteins are commonly developed in coal measures of Carboniferous-Permian and stable in horizon.They occur as thin beds less than 1m (some only 0.02 ± m.) in thickness but their thickness keep constant in thousands of km2, so they may be used as isochronous correlative horizons. The contact between the top and bottom surfaces of tonstein bed and coal is generally distinct and even, and has no indication of current scour.The bedding is not developed, and generally has massive structure.Tonstcins arc usually drak-brown in coal bed, because they contain organic carbon, but arc greyish white in coal-free bed. The mineral compositions are very simple.They are mainly composed of kaolinite and kalolinite-dickitc. Their textures are very complex and diverse, from cryptocrystalline to macrocrystalline vermicular crystals of kaolinite, and some intact pseudocrystals of feldspar are composed of microcrystalline kaolinite. The degree of order of kaolinites differs by X-ray diffraction analysis, and is generally proportional to the size of crystal. The degree of order of macrocrystal of kaolinite is high. The degree of order of cryprocrystalline kaolinite is low. The macrocrystalline kaolinite contains usually minor dickite. There are two cndothcrmic peaks at 590 and 670 on differential thermal curve. After heat treatment(550℃)the samples have still (00l)and (002)pcaks on X-ray diffraction spectrum, so the presence of dickite may be confirmed further. The content of crystal fragment of primary mineral is low, but is the main basis to analysis the source of material. The chemical compositions of tonsteins are quite simple too. They are mostly silica (45% ± ), alumina (35%± ), and water (13% ± ), total is 95% ± . The molecular ratio SiO2/ Al2O3of monomineralic tonstein is close to near 2. The contents of K2O, Na2O, CaO and MgO are lower.The trace elements more than 30 were determined by emission spectroscopy using an inductive coupled plasma (ICP). According to this result the contents of iron family elements (Fe, Ti, Mn, V, Cr, Ni, Co)are lower, but those of Th, U, B and Zr are higher. The ratio of Ti to Th is near to acid magmtic rock. Based on colour and textural features three typical tonsteins are common: 1. Light coloured crystallinoclast-bearing macrocrystalline tonstein. 2. Dark-bropwm, macrocrystallin tonstein 3. Brown-grey microcrystalline tonstein. The difference of tonstein from common shale and mudstone lies in that the former is widely distributed, thin, stable in horizon, and not developed in bedding. The main difference is that tonstein is exceedingly simple in material composition, the kaolinite contained absolutely predominates and contains a little dickite, the crystallinoclasts of primary mineral include hypothermal mineral assemblages, the Al2O3content is higher, the contents of K2O, Na2O, CaO and MgO are lower, the iron family elements contents are lower, and radioactive element content is higher. According to the above mentioned distribution, occurrence, texture, structure, particularly mineral and chemical compositions of tonsteins. the material originated from acid volcanic ashes. The tonsteins have important significance in event stratigraphy and greater economic value. However, at present for the tonstein there are little expoundings in sedimentary petrology, and almost no proper position, these deserving extra attention also.
1989, 7(1): 117-125.
Abstract:
Fluorescence spectroscopy is a useful technique for the characteristion of hydrocarbons mixture in the marine enviornment and panicularly useful for the detection and measurement of organic compounds with one to four or more aromatic ring.However, by using fixed wavelength and synchronous scanning fluorescence, spectra of complex mixture can not be satisfactory resolved. A newly developed three dimensional total scanning fluorescence by Brooks and Kennicutt can overcome these disadvantages above mention, and it can combine with computer to process all datum acquied rapidly and accurately. This paper is to demonatrate polynuclear aromatic hydrocarbons in surface sediments which were semi- quantitatively determined by three dimensional total scanning fluorescence for nine stations on a transect of the Changjiang estuary and adjacent continental shelf (30 ° 16 ' to 31°30 ' N and 123 ° 30 ' to 124°30 ' E) . These samples were taken from the top 10cm section of each core, The percent content of total organic carbons (0. 39 to 0. 13% ) and extractable lipids( 63 to 20ppm) were also determined. Both of which decreased dramatically for these stations within the east of 123 ° E. The fluorescence measurement was conducted on a perkin - Elmer (PE) 650-40UV spectrofluorometer controlled by PE-3600 data station with special " SCANR" program by Brooks . Both the hexane and methylene dichloidc sediment extracts were scanned directly, after concentration by Rotovaparation, within a 200to 600nm for both emission and excitation wavelength to acquired a three dimensional total scanning fluorescence spectrum of emission wavelength, excitation wavelenegth and intensity, and contour presentations, the fluorescence results acquired were very similar to those of recent marine sediments from other continental shelf areas. Perylene was detected in sediment for all stations. Become well known, perylene is one of characteristic organic compounds of typical terrigenous higher plant, Therefore, it might be thought that organic matter presented in sediment came from river load. Both concentration of total aromatic hydrocarbons and perylene decreased generally with distance from shore. Their average fluorescence intensity ( 154542 and 1678 respectively )for the first five stations of the west of 123 ?E were markedly higher more than for the second four stations at the east of 123 ° E (62216 for PAHs and 371 for perylene respectively ) . By comparing three dimensional total scanning fluorescence presentation of authantic standards, it showed that fluorescence results acquired for less than 370nm of excitation wavelength belonged to non - perylene aromatic mixture with two to four rings. The non - perylene fluorescence intergrated intensity was found to be more than 80 percent for both hexane and methylene dichloride extracts for the first three stations at nearshore, and more than 60% for most of stations. And decreased generally with distance offshore. The more intense the non - perylene fluorescence the greater the amount of migrated hydrocarbons in the sediment samples. On the basis of the fact that the non - perylene aromatic hydrocarbons concentration is heigher at near Changjiang mouth and lower seaward . It is must likely that the migrated hydrocarbons in sediments primarilly came from Changjiang river loads. Most of them were first deposited into seabottom. By comprehension studying these data acquired and their variance trends in amount for hydrocarbons, it might be thought that organic matter in sediment mainly comes form Changjinag river terrigenous suspended matter and also decreased with distance from river mounth. Most of them were deposited to the west of 123 ° E in Changjiang estuary. It is in agreement those of other methods by authors of this paper and of other marine geologists for the same study area.
Fluorescence spectroscopy is a useful technique for the characteristion of hydrocarbons mixture in the marine enviornment and panicularly useful for the detection and measurement of organic compounds with one to four or more aromatic ring.However, by using fixed wavelength and synchronous scanning fluorescence, spectra of complex mixture can not be satisfactory resolved. A newly developed three dimensional total scanning fluorescence by Brooks and Kennicutt can overcome these disadvantages above mention, and it can combine with computer to process all datum acquied rapidly and accurately. This paper is to demonatrate polynuclear aromatic hydrocarbons in surface sediments which were semi- quantitatively determined by three dimensional total scanning fluorescence for nine stations on a transect of the Changjiang estuary and adjacent continental shelf (30 ° 16 ' to 31°30 ' N and 123 ° 30 ' to 124°30 ' E) . These samples were taken from the top 10cm section of each core, The percent content of total organic carbons (0. 39 to 0. 13% ) and extractable lipids( 63 to 20ppm) were also determined. Both of which decreased dramatically for these stations within the east of 123 ° E. The fluorescence measurement was conducted on a perkin - Elmer (PE) 650-40UV spectrofluorometer controlled by PE-3600 data station with special " SCANR" program by Brooks . Both the hexane and methylene dichloidc sediment extracts were scanned directly, after concentration by Rotovaparation, within a 200to 600nm for both emission and excitation wavelength to acquired a three dimensional total scanning fluorescence spectrum of emission wavelength, excitation wavelenegth and intensity, and contour presentations, the fluorescence results acquired were very similar to those of recent marine sediments from other continental shelf areas. Perylene was detected in sediment for all stations. Become well known, perylene is one of characteristic organic compounds of typical terrigenous higher plant, Therefore, it might be thought that organic matter presented in sediment came from river load. Both concentration of total aromatic hydrocarbons and perylene decreased generally with distance from shore. Their average fluorescence intensity ( 154542 and 1678 respectively )for the first five stations of the west of 123 ?E were markedly higher more than for the second four stations at the east of 123 ° E (62216 for PAHs and 371 for perylene respectively ) . By comparing three dimensional total scanning fluorescence presentation of authantic standards, it showed that fluorescence results acquired for less than 370nm of excitation wavelength belonged to non - perylene aromatic mixture with two to four rings. The non - perylene fluorescence intergrated intensity was found to be more than 80 percent for both hexane and methylene dichloride extracts for the first three stations at nearshore, and more than 60% for most of stations. And decreased generally with distance offshore. The more intense the non - perylene fluorescence the greater the amount of migrated hydrocarbons in the sediment samples. On the basis of the fact that the non - perylene aromatic hydrocarbons concentration is heigher at near Changjiang mouth and lower seaward . It is must likely that the migrated hydrocarbons in sediments primarilly came from Changjiang river loads. Most of them were first deposited into seabottom. By comprehension studying these data acquired and their variance trends in amount for hydrocarbons, it might be thought that organic matter in sediment mainly comes form Changjinag river terrigenous suspended matter and also decreased with distance from river mounth. Most of them were deposited to the west of 123 ° E in Changjiang estuary. It is in agreement those of other methods by authors of this paper and of other marine geologists for the same study area.
1989, 7(1): 135-142.
Abstract:
Tidal action was extremely strong in semi-enclosed epeiric sea connecting with wide sea, the epeiric sea was named Tidal Sea.Near the narrow tidal passageway, there was a fine environment to create subaqueous tidal delta.Because zhujiangkou Basin was provided with above natural geographic condition during early deposition in the lower Miocene, a large suite of subaqueous tidal delta sand body was developed.It became one of the most important sedimentary face in that period. In Zhujiangkou Basin, the first widely transgression took place in the late of the South China Sea formed.The transgression passageway was a long and narrow area between the south of the basin and wide sea, the west boundary of "passageway" was formed by a NW trend boundary fundamental fault.The fault was a long growth fault with 140km, and was occurcd during the basin rifted in Eogene.Its south part was an o val igneous body (granitic intrusion in the Yanshan movement) and cut off the edge of the north convex oceanic crust.Because of the defence action of igneous body, the transgression had not taken place in Eogenc.Thc strong tcctogcncsis in the late Otigocenc ended sealed state of the basin before. As the whole of shelf area subsiding in the late of tectonic movement, the projecting igneous body gradually sank under water and the basin finaly integrated with wide sea. Analyseing the passageway of transgression the authors considered that it showed a funnclshapcd and the narrowest part is about 30 km and equate to that of igneous body. The strong tidal action altered normal sedimentary differentiation of the basin and sandstones were commonly developed during the period.The sandstone was charactered "divagated sand", the thickness was more than 65 percent of that of stratum in the south of the basin (inside of the strait) where was far from main source area, and was considered as developed area of subaqueous tidal delta. Tidal delta of Zhujiangkou Basin covered the superposed distribution area of about 10000 km2, the thickness was about several hundred meters. Single layer sandbody often occured with lens- shaped, the thickest part was about 60m. Here, and was called as tidal sandstone bar in this paper.In the cross section, the tidal delta consisted of multiserial reversed rhythmic sand which changed from fine to coarse upward by superposition. The sandstones were cleaner, lower argillaceous content, and middle to poorly sorted. It reflected the high energy environment and fast buried history when tidal flowed in or out basin. Nonsequence current bedding, veined bedding and cross- stratification were common stratification in tidal sand bar. Slump (mix) structure developed at top of sand bed, and indicated that the structure sometimes emerged water surface and formed littoral island land form in the late of tidal sand bar. The collapse in the edge was the reason of causing mixed and disorderly accumulation. The tidal delta sandstone was high mature degree, and was feldsparthic quartz sandstone without debris.Thc most steady heavy mineral content was twice to four times as much as that in source area. It showed that the sandstone was deposited after long distance moving, and further proved the inference that material source of the northern palaeo Zhujiang enriches nearby the tidal passageway by both moving of river and tidal race. Tidal race was also a kind of tractive current the same as river, but the tidal race was a estuarine flow which flow area was wide and flow rate altered regularly, that is, the rate decreased when flowed in the basin, and the rate increased when flowed out the basin. It caused obvious zonal phenomenon of different grained sands. The river was often limited in a narrow channel, its deposition characteristic was changeable flow rate and widely dispersed area of grained- degree.Therefore. grain-size structural paramerters of both appeared obviously difference. In the declination and standard deviation (σI - SKI ) divergent map of grain sample, the dots of sand of tidal sand bar were within a elliptic area, SK I value was 0.35-0.65. and showed very positive skew. σ I was 1.0-185.But SK I of Feilideman modern river and other fossil river sands were mainly -0.4-0.3 and showed positiveskew, approximately symmetry and negative skew, no very positive skew.In CM map. the sands of tidal sand barwere short of rolling and homogeneous suspended components which were common in the river sand.This was possibly concerned with lacking very coarse and very fine grain sand in the sample (mainly middle sand. lessfine-middle sand and coarse-middle).It was also short of rolling component is the curie of probability distribu-don.
Tidal action was extremely strong in semi-enclosed epeiric sea connecting with wide sea, the epeiric sea was named Tidal Sea.Near the narrow tidal passageway, there was a fine environment to create subaqueous tidal delta.Because zhujiangkou Basin was provided with above natural geographic condition during early deposition in the lower Miocene, a large suite of subaqueous tidal delta sand body was developed.It became one of the most important sedimentary face in that period. In Zhujiangkou Basin, the first widely transgression took place in the late of the South China Sea formed.The transgression passageway was a long and narrow area between the south of the basin and wide sea, the west boundary of "passageway" was formed by a NW trend boundary fundamental fault.The fault was a long growth fault with 140km, and was occurcd during the basin rifted in Eogene.Its south part was an o val igneous body (granitic intrusion in the Yanshan movement) and cut off the edge of the north convex oceanic crust.Because of the defence action of igneous body, the transgression had not taken place in Eogenc.Thc strong tcctogcncsis in the late Otigocenc ended sealed state of the basin before. As the whole of shelf area subsiding in the late of tectonic movement, the projecting igneous body gradually sank under water and the basin finaly integrated with wide sea. Analyseing the passageway of transgression the authors considered that it showed a funnclshapcd and the narrowest part is about 30 km and equate to that of igneous body. The strong tidal action altered normal sedimentary differentiation of the basin and sandstones were commonly developed during the period.The sandstone was charactered "divagated sand", the thickness was more than 65 percent of that of stratum in the south of the basin (inside of the strait) where was far from main source area, and was considered as developed area of subaqueous tidal delta. Tidal delta of Zhujiangkou Basin covered the superposed distribution area of about 10000 km2, the thickness was about several hundred meters. Single layer sandbody often occured with lens- shaped, the thickest part was about 60m. Here, and was called as tidal sandstone bar in this paper.In the cross section, the tidal delta consisted of multiserial reversed rhythmic sand which changed from fine to coarse upward by superposition. The sandstones were cleaner, lower argillaceous content, and middle to poorly sorted. It reflected the high energy environment and fast buried history when tidal flowed in or out basin. Nonsequence current bedding, veined bedding and cross- stratification were common stratification in tidal sand bar. Slump (mix) structure developed at top of sand bed, and indicated that the structure sometimes emerged water surface and formed littoral island land form in the late of tidal sand bar. The collapse in the edge was the reason of causing mixed and disorderly accumulation. The tidal delta sandstone was high mature degree, and was feldsparthic quartz sandstone without debris.Thc most steady heavy mineral content was twice to four times as much as that in source area. It showed that the sandstone was deposited after long distance moving, and further proved the inference that material source of the northern palaeo Zhujiang enriches nearby the tidal passageway by both moving of river and tidal race. Tidal race was also a kind of tractive current the same as river, but the tidal race was a estuarine flow which flow area was wide and flow rate altered regularly, that is, the rate decreased when flowed in the basin, and the rate increased when flowed out the basin. It caused obvious zonal phenomenon of different grained sands. The river was often limited in a narrow channel, its deposition characteristic was changeable flow rate and widely dispersed area of grained- degree.Therefore. grain-size structural paramerters of both appeared obviously difference. In the declination and standard deviation (σI - SKI ) divergent map of grain sample, the dots of sand of tidal sand bar were within a elliptic area, SK I value was 0.35-0.65. and showed very positive skew. σ I was 1.0-185.But SK I of Feilideman modern river and other fossil river sands were mainly -0.4-0.3 and showed positiveskew, approximately symmetry and negative skew, no very positive skew.In CM map. the sands of tidal sand barwere short of rolling and homogeneous suspended components which were common in the river sand.This was possibly concerned with lacking very coarse and very fine grain sand in the sample (mainly middle sand. lessfine-middle sand and coarse-middle).It was also short of rolling component is the curie of probability distribu-don.
1989, 7(1): 11-28.
Abstract:
Petrographic studies of Cretaceous-Tertiary red-beds in the Xiyaer Gang region of Northern Tibet indicate diagenetic alteration of the minerology and texture of the clastic sedimentary rocks, and suggest a diagenetic origin for their red-purple colour. The rocks were deposited in alluvial fan and upper fan delta environments. The mineralogy has been altered by addition of mechanically infiltrated clays (detrital in or-rgin), by dissolution of unstable minerals and rock fragments, and precipitation of authigenic minerals. The textures show alteration by the processes of: (i) infiltration of detrital clay and formation of authigenic clay minerals which form an interstitial clay matrix not present in the original sediment, (ii) dissolution of framework grains, (iii) replacement and recrystallisation. Two principal diagenetic environments are recognized: (1) the early shallow burial diagenetic environment which is controlled by depositional environment, sedimentation and climate. It is comparable to near-surface carbonate diagenetic environments; (2) deep burial environment of the later stages of diagenesis which is controlled by the gcochemical conditions of pore water, and pressure-temperature regimes.
Petrographic studies of Cretaceous-Tertiary red-beds in the Xiyaer Gang region of Northern Tibet indicate diagenetic alteration of the minerology and texture of the clastic sedimentary rocks, and suggest a diagenetic origin for their red-purple colour. The rocks were deposited in alluvial fan and upper fan delta environments. The mineralogy has been altered by addition of mechanically infiltrated clays (detrital in or-rgin), by dissolution of unstable minerals and rock fragments, and precipitation of authigenic minerals. The textures show alteration by the processes of: (i) infiltration of detrital clay and formation of authigenic clay minerals which form an interstitial clay matrix not present in the original sediment, (ii) dissolution of framework grains, (iii) replacement and recrystallisation. Two principal diagenetic environments are recognized: (1) the early shallow burial diagenetic environment which is controlled by depositional environment, sedimentation and climate. It is comparable to near-surface carbonate diagenetic environments; (2) deep burial environment of the later stages of diagenesis which is controlled by the gcochemical conditions of pore water, and pressure-temperature regimes.
1989, 7(1): 39-47.
Abstract:
Based on the regional observations of the undercompaction and the abnormal formation pressure occurring in the source rocks of Late Jurassic and Early Cretaceous layers and of other data in Jiuxi Basin, the authors suggest that the undercompaction and abnormal pressure of argillaceous of this area is mainly caused by compaction unequilibrium and by hydrocarbon generation, while the dehydration of clay mineral and aquathermal pressuring effects are not important. The abnormal pressure with pressure coefficients about 1.2-1.3 of this area can be the driving forces of oil primary migration. The combined effect of abnormal pressure plus tectonic stress can creat microfracture. After analysis the diameters not only of the source rock' s pore and of hydrocarbon molccullar's but also of the pollen's and spore's from crude oil, the authors suggest that the pore of the source rock can allow hydrocarbon migration. Because the diameters of the pollen and spore from oil are much larger than the pore size of the source rock's, the microfracture should be the important passage of oil primary migration. This paper also deals with the problem of the phases in primary migration of petroleum. The composition comparison between the extracts of the rocks and the cruds oils shows that the saturated hydrocarbons which arc among the least water-soluble, are enriched in cruid oils. At the same time, the estimation of the hydrocarbon abundance in the pore fluid from the pyrolysis data and the porosity decrease through oil window supports that the solubility of the hydrocarbon in the solution would reach 7188-82250ppm if the migration phase were molecular solution. This ideal solubility is obviously much higher than the actual solubilty, so it is impossible that the molecular solution is the principle mode of primary migrarion of pertoleum. At the end of this paper, from the comparison of the critical heights of different oil traps, secondary migration conditions of this area are discussed. The importance of hydrodynamic action in the Baidong- Danbei hydrodynamic trap is also analysed.
Based on the regional observations of the undercompaction and the abnormal formation pressure occurring in the source rocks of Late Jurassic and Early Cretaceous layers and of other data in Jiuxi Basin, the authors suggest that the undercompaction and abnormal pressure of argillaceous of this area is mainly caused by compaction unequilibrium and by hydrocarbon generation, while the dehydration of clay mineral and aquathermal pressuring effects are not important. The abnormal pressure with pressure coefficients about 1.2-1.3 of this area can be the driving forces of oil primary migration. The combined effect of abnormal pressure plus tectonic stress can creat microfracture. After analysis the diameters not only of the source rock' s pore and of hydrocarbon molccullar's but also of the pollen's and spore's from crude oil, the authors suggest that the pore of the source rock can allow hydrocarbon migration. Because the diameters of the pollen and spore from oil are much larger than the pore size of the source rock's, the microfracture should be the important passage of oil primary migration. This paper also deals with the problem of the phases in primary migration of petroleum. The composition comparison between the extracts of the rocks and the cruds oils shows that the saturated hydrocarbons which arc among the least water-soluble, are enriched in cruid oils. At the same time, the estimation of the hydrocarbon abundance in the pore fluid from the pyrolysis data and the porosity decrease through oil window supports that the solubility of the hydrocarbon in the solution would reach 7188-82250ppm if the migration phase were molecular solution. This ideal solubility is obviously much higher than the actual solubilty, so it is impossible that the molecular solution is the principle mode of primary migrarion of pertoleum. At the end of this paper, from the comparison of the critical heights of different oil traps, secondary migration conditions of this area are discussed. The importance of hydrodynamic action in the Baidong- Danbei hydrodynamic trap is also analysed.
1989, 7(1): 71-80.
Abstract:
To coordinate the exploration of oil-gas traps in nonanticline. this paper studies the reservoir in the lower part of the third member of Shahejie Formation in Neogene. Zangxi depression. Through observation of cores, electric logging, lithoiogy and useing of over 10 laboratory test data and studies of samaple data more than 2700 in 24 wells, this paper gives details or the distributions, forming conditions, sedimentary features, genesis. sedinentary microfacics, influnce factors of ability for reservoir, and evaluation of bearing oil- gas for the sandbodies. Authors consider that the sandbody type belongs to the submarine fan which comes from the deposition of gravity current. The sandbodies develop in the center of the depression. Those can be classified into 6 fans which occur in the same region. The area of the sixth fan is the largest one. The major part of sandbodies is the thickest in the deepest place of the depression. From the bottom to the top of the formation, the distributions of the sandbodies become little and thin. During the formation of sandbodies, the paleoclimate wsa warm and humid, the paleotopography steep on the eastern and western coastline of the lake. The center of the lake was underground paleouplift. Its east and west pans were depression favorable to the sedimentation of subaqueous fan. The lake filled fresh water with a little salinity. During the drop of the crust continuously, the water became larger, from semi-deep lake to deep lake, with plenty of algae. The lake became a good source area. Gravity clastic sediment, which genesis was mainly mixed with type of grain- fragment current, derived from mesozoic, paleozoic group of the east and west area of the lake, and from the shore and sallow lake. The subaqueous fan can be classified into 5 microfacies, i.e. main channel, subaqueous levee, braided channle, and interchannel. Evaluation of reservoir in studying area is following. There are the best reservoirs in the center of the eastern depression; The fourth, fifth, sixth fans are the most favorable reservoirs; the second and third rather good, the first bad; Braided channle is the best and main channel is good for reservoir. The lower part of the third member of Shahejie is in the middle age of late diagenesis. The primary porosity or the sandstone has decreased, but the secondary interparticle porosity well developed in the lower than the upper of the sandstone. The control factors of rich oil-gas in studying area are followings: 1. Havine plenty source rock with large distribution, the source rock has matured in the depression, which produced a lot of oil-gas; 2. Having good associations of source rock, reservoir, and cover, the numerous grav ci rent subaqeous fan has been separated by the mature source rock, contituting combination of self-genents of oil self-reservoir, and self-cover; 3. the braided channel of the middle fan is a favorable facieszonc for reservoir, with a large thickness and area; 4. The depositional mechcnism and diagenesis are major factors controlling oil-gas. The sandbodies formed from mechanism of grain-fragment current have the texture of grain supported, bearing oil-gas high level in the place of strong secondary solution, but bearing oil-gas is low level in the sandbodies of matrix supported producing from the low density flow; 5. Having favorable lithological oil-gas traps. The fourth member of Shanhcjie Formation-Kongdian-Formation, and mesozoic group have been deduced to be benefical to exploration. The west of the depression and Gunan depression may have the same depositional condition as the east of the depression. It is possible to find a oilfield like, Wuhuazhuang oilfield.
To coordinate the exploration of oil-gas traps in nonanticline. this paper studies the reservoir in the lower part of the third member of Shahejie Formation in Neogene. Zangxi depression. Through observation of cores, electric logging, lithoiogy and useing of over 10 laboratory test data and studies of samaple data more than 2700 in 24 wells, this paper gives details or the distributions, forming conditions, sedimentary features, genesis. sedinentary microfacics, influnce factors of ability for reservoir, and evaluation of bearing oil- gas for the sandbodies. Authors consider that the sandbody type belongs to the submarine fan which comes from the deposition of gravity current. The sandbodies develop in the center of the depression. Those can be classified into 6 fans which occur in the same region. The area of the sixth fan is the largest one. The major part of sandbodies is the thickest in the deepest place of the depression. From the bottom to the top of the formation, the distributions of the sandbodies become little and thin. During the formation of sandbodies, the paleoclimate wsa warm and humid, the paleotopography steep on the eastern and western coastline of the lake. The center of the lake was underground paleouplift. Its east and west pans were depression favorable to the sedimentation of subaqueous fan. The lake filled fresh water with a little salinity. During the drop of the crust continuously, the water became larger, from semi-deep lake to deep lake, with plenty of algae. The lake became a good source area. Gravity clastic sediment, which genesis was mainly mixed with type of grain- fragment current, derived from mesozoic, paleozoic group of the east and west area of the lake, and from the shore and sallow lake. The subaqueous fan can be classified into 5 microfacies, i.e. main channel, subaqueous levee, braided channle, and interchannel. Evaluation of reservoir in studying area is following. There are the best reservoirs in the center of the eastern depression; The fourth, fifth, sixth fans are the most favorable reservoirs; the second and third rather good, the first bad; Braided channle is the best and main channel is good for reservoir. The lower part of the third member of Shahejie is in the middle age of late diagenesis. The primary porosity or the sandstone has decreased, but the secondary interparticle porosity well developed in the lower than the upper of the sandstone. The control factors of rich oil-gas in studying area are followings: 1. Havine plenty source rock with large distribution, the source rock has matured in the depression, which produced a lot of oil-gas; 2. Having good associations of source rock, reservoir, and cover, the numerous grav ci rent subaqeous fan has been separated by the mature source rock, contituting combination of self-genents of oil self-reservoir, and self-cover; 3. the braided channel of the middle fan is a favorable facieszonc for reservoir, with a large thickness and area; 4. The depositional mechcnism and diagenesis are major factors controlling oil-gas. The sandbodies formed from mechanism of grain-fragment current have the texture of grain supported, bearing oil-gas high level in the place of strong secondary solution, but bearing oil-gas is low level in the sandbodies of matrix supported producing from the low density flow; 5. Having favorable lithological oil-gas traps. The fourth member of Shanhcjie Formation-Kongdian-Formation, and mesozoic group have been deduced to be benefical to exploration. The west of the depression and Gunan depression may have the same depositional condition as the east of the depression. It is possible to find a oilfield like, Wuhuazhuang oilfield.
1989, 7(1): 91-99.
Abstract:
The coal bed in Shouyang coal field was composed mainly of Taiyuan Group(C3t) and Shanxi Group(Pls) containing 9 to 14 seams. The abounded coal reserve of this region made itself one of the important bases of en- ergy. The Taiyuan Group in this district can be divided into five complete cycles of sequence. containing 6-8 coal seams, and was made up of light gray, dark gray and grayish black mudstone. siltpelite, carbonaceous mudstone. silt-stone. sandstone, limestone and coal seams. Aaording to the sedimentogaghy, the authors con- sidered environment that Taiyuan goup of this area belonged to the transitional environment deposite. The lower three cycles i.e.the 1st, 2nd. 3rd were built up of continental elastic debris tidal Ilat deposition under marine regression and lower intertidal carbonate under marine inundation, while the upper two cycles (the 4th and 5th) belonged to deltaic deposition. The Shanzi Group in this district containing 3-6 coal seams, consisted of gray and black mudstone, sandy mudstone, carbonaceous mudstone, ailtstone, sandstone and coal seams. On studying its sedimentation mechanism in detail. the authors proposed that the formation of Shanxi Group is not “purely continental”as been known before, but as deltaic deposition. It can also be divided into five cycles (the 6th. 7th, 8th, 9th and 10th) most of them represent developing deltaic deposition ezcept the cycle 6 which showed complete sequence of delta deposition The relationship between the depositional environment and the property of coal seams are as follows: The 15th. 13th, 12th and 11th coal seams. located at the lower three cycles of the Taiyuan Group, were deposited under tidal flat environment. The characteristics of this sequence can be described in following words; the formations below each coal seam belonged to sea ebb sequence its continental clastic debris represent tidal flat
The coal bed in Shouyang coal field was composed mainly of Taiyuan Group(C3t) and Shanxi Group(Pls) containing 9 to 14 seams. The abounded coal reserve of this region made itself one of the important bases of en- ergy. The Taiyuan Group in this district can be divided into five complete cycles of sequence. containing 6-8 coal seams, and was made up of light gray, dark gray and grayish black mudstone. siltpelite, carbonaceous mudstone. silt-stone. sandstone, limestone and coal seams. Aaording to the sedimentogaghy, the authors con- sidered environment that Taiyuan goup of this area belonged to the transitional environment deposite. The lower three cycles i.e.the 1st, 2nd. 3rd were built up of continental elastic debris tidal Ilat deposition under marine regression and lower intertidal carbonate under marine inundation, while the upper two cycles (the 4th and 5th) belonged to deltaic deposition. The Shanzi Group in this district containing 3-6 coal seams, consisted of gray and black mudstone, sandy mudstone, carbonaceous mudstone, ailtstone, sandstone and coal seams. On studying its sedimentation mechanism in detail. the authors proposed that the formation of Shanxi Group is not “purely continental”as been known before, but as deltaic deposition. It can also be divided into five cycles (the 6th. 7th, 8th, 9th and 10th) most of them represent developing deltaic deposition ezcept the cycle 6 which showed complete sequence of delta deposition The relationship between the depositional environment and the property of coal seams are as follows: The 15th. 13th, 12th and 11th coal seams. located at the lower three cycles of the Taiyuan Group, were deposited under tidal flat environment. The characteristics of this sequence can be described in following words; the formations below each coal seam belonged to sea ebb sequence its continental clastic debris represent tidal flat
1989, 7(1): 109-116.
Abstract:
Malan loess section in Heimugou location of Luochuan County, Shaanxi Province, has been studied. From the top of the section at 2.56m to the end at 10.36m, we collected samples by intervals of 20cm, total 40 samples were collected. The samples were dated by thermoluminescent(TL) method. Depositional rate of the Malan loess and the regularity of its variation as well as its geological significance are discussed in the paper. Average depositional rate of the Malan loess for whole section is 0.078mm/ a. According to the variation in the depositional rate, the section can be divided into three horizons. Horizon 1 is in interval 2.56-3.56m, with its average dipositional rate of 0.091mm/ a. Horizon 2 is in interval 3.56-7.76m with average depositional rate of 0.35mm / a. Horizon 3 is in interval 7.76-10.36m, with average depositional rate 0.058mm / a. The variation of dcpositional rate has following geological significance. (1) Depositional rate of the Malan loess is closely related to the grain size. The grain of the lower part is coarse, well graded the depositional rate is least. The grain of middle part is fine, not well graded, the dcpositional rate is higher.The upper part is similar to the lower part. (2) The depositional rate of the Malan loess is somewhat correlated to the distrbution and character of10Be concentration along the cross section. The average 10Be precipitation rate in the middle part is highest. The dcpositional rate or loess in this layer is also highest. But the average depositional rate of loess in the upper and lower parts is lowest, the average10Be precipitaion rate is also lowest. 10Be camefrom the atmosphere and absorbed by aerosol, and then reached the earth's surface by rainfall and dustfalls. Finegrained aerosol probable more absorbed 10Be and its precipitation rate is higher than the coarse grains, so the 10Be concentration in fine grains is higher than in coares. (3) The variation of the depositional rate of the loess depends on the climatic evolution. from Zhang Deer, the more dry and arid the climate, the more frequent the precipitation of the loess. The loess has also deposited during cold climate. On the contrary, the warm and humid climate did not favorable to loess dcposite. The locss-palcosoil sequence reflects climatic cycle in that time. Cold-warm and dry -humid climates alternated frequently. The climatic change reflected by loess-palcosoil sequence was in large scale and long inter time. Authors call it the first-ordcd indicator of paleoclimatic change. The paleoclimatic change reflected by depositional rate is called second-order indicator of the paleoclimatic change, because it is a change in the loess of sub-order stratigraphic unit. The high depositional rate was during the dry-cold climate and deositional rate is lower during the warm-humid climate.
Malan loess section in Heimugou location of Luochuan County, Shaanxi Province, has been studied. From the top of the section at 2.56m to the end at 10.36m, we collected samples by intervals of 20cm, total 40 samples were collected. The samples were dated by thermoluminescent(TL) method. Depositional rate of the Malan loess and the regularity of its variation as well as its geological significance are discussed in the paper. Average depositional rate of the Malan loess for whole section is 0.078mm/ a. According to the variation in the depositional rate, the section can be divided into three horizons. Horizon 1 is in interval 2.56-3.56m, with its average dipositional rate of 0.091mm/ a. Horizon 2 is in interval 3.56-7.76m with average depositional rate of 0.35mm / a. Horizon 3 is in interval 7.76-10.36m, with average depositional rate 0.058mm / a. The variation of dcpositional rate has following geological significance. (1) Depositional rate of the Malan loess is closely related to the grain size. The grain of the lower part is coarse, well graded the depositional rate is least. The grain of middle part is fine, not well graded, the dcpositional rate is higher.The upper part is similar to the lower part. (2) The depositional rate of the Malan loess is somewhat correlated to the distrbution and character of10Be concentration along the cross section. The average 10Be precipitation rate in the middle part is highest. The dcpositional rate or loess in this layer is also highest. But the average depositional rate of loess in the upper and lower parts is lowest, the average10Be precipitaion rate is also lowest. 10Be camefrom the atmosphere and absorbed by aerosol, and then reached the earth's surface by rainfall and dustfalls. Finegrained aerosol probable more absorbed 10Be and its precipitation rate is higher than the coarse grains, so the 10Be concentration in fine grains is higher than in coares. (3) The variation of the depositional rate of the loess depends on the climatic evolution. from Zhang Deer, the more dry and arid the climate, the more frequent the precipitation of the loess. The loess has also deposited during cold climate. On the contrary, the warm and humid climate did not favorable to loess dcposite. The locss-palcosoil sequence reflects climatic cycle in that time. Cold-warm and dry -humid climates alternated frequently. The climatic change reflected by loess-palcosoil sequence was in large scale and long inter time. Authors call it the first-ordcd indicator of paleoclimatic change. The paleoclimatic change reflected by depositional rate is called second-order indicator of the paleoclimatic change, because it is a change in the loess of sub-order stratigraphic unit. The high depositional rate was during the dry-cold climate and deositional rate is lower during the warm-humid climate.
1989, 7(1): 127-134.
Abstract:
In the low mountain and hill area on the east and the west coast of the Liaodong Bay. owing to long period of slow crustal uplifting, the Quaternary loose sediment is very thin or even absent; in coastal plains near river mouths, Quaternary system, generally speaking, is 20- 50 metres thick. But in the top of Liaodong Bay, the depth of Quaternary sediment in the lower Liaohe River plain whose foundation has been continuelly descending can reach 359 metres.Lower Liaohe River plain was the centre of Quaternary sedimentation in the province of Liaoning.Inthe plain, from north to south, from the two sides to the centre line, the depth of Quaternary sediments gradually accreted, the grain size changed from coarse to fine and the number of lithological units accreted also. In the vertical sections, the grain size of Quaternary sediments changed from pebble and cobble mingled with clay in the bottom to pebble, coarse sand find sand in the middle part, and silt on the top. The evolution of sedimentary environment along the Liaodong Bay was controlled by the changes of paleoclimate, sea level changes, neotectonic movement and geomorphologic condition.The developing process of the fans of the Dalinhe River and the Xiaolinhe River, formed in middle and late pleistocene, could reflected the evolution trend of sedimentary environment of the studied area. In glacial period the product of mechanical weathering in the low mountain and hill area was mainly coarse-grained and owing to the descending of sea level, the increase of hydraulic gradient and surface water transportation, a large quantity of fragments by mechanical weathering were transported to the plain area in which a series of coarse grained sediments were formed.In western Liaoning, diluvial fan in pediment area stretched to the plain area in glacial period and retread to the mountain area in intergracial period, In intergracial period, besides mechanical weathering, chemical and biological weathering increased in this period produced a large quantity of fine- grained material and a series of fine-grained sediments were formed in the plain area.The descending scale of the lower Liaohe River plain after late pleistocene was smaller than before and the master rivers of the Dalinhe River and the Xiaolinhe River transferred to west, so that the fan of the Dalinhe River and the Xiaolinhe River moved and incressed.Three times of transgression which were different in their extent occurred in the coastal area of the Liaodong Bay in Quaternary and marine formation and marine-continental formation devclopped in the area.The alternation of transgression and regression resulted in the changes of sedimentary environments and sedimentary facies.
In the low mountain and hill area on the east and the west coast of the Liaodong Bay. owing to long period of slow crustal uplifting, the Quaternary loose sediment is very thin or even absent; in coastal plains near river mouths, Quaternary system, generally speaking, is 20- 50 metres thick. But in the top of Liaodong Bay, the depth of Quaternary sediment in the lower Liaohe River plain whose foundation has been continuelly descending can reach 359 metres.Lower Liaohe River plain was the centre of Quaternary sedimentation in the province of Liaoning.Inthe plain, from north to south, from the two sides to the centre line, the depth of Quaternary sediments gradually accreted, the grain size changed from coarse to fine and the number of lithological units accreted also. In the vertical sections, the grain size of Quaternary sediments changed from pebble and cobble mingled with clay in the bottom to pebble, coarse sand find sand in the middle part, and silt on the top. The evolution of sedimentary environment along the Liaodong Bay was controlled by the changes of paleoclimate, sea level changes, neotectonic movement and geomorphologic condition.The developing process of the fans of the Dalinhe River and the Xiaolinhe River, formed in middle and late pleistocene, could reflected the evolution trend of sedimentary environment of the studied area. In glacial period the product of mechanical weathering in the low mountain and hill area was mainly coarse-grained and owing to the descending of sea level, the increase of hydraulic gradient and surface water transportation, a large quantity of fragments by mechanical weathering were transported to the plain area in which a series of coarse grained sediments were formed.In western Liaoning, diluvial fan in pediment area stretched to the plain area in glacial period and retread to the mountain area in intergracial period, In intergracial period, besides mechanical weathering, chemical and biological weathering increased in this period produced a large quantity of fine- grained material and a series of fine-grained sediments were formed in the plain area.The descending scale of the lower Liaohe River plain after late pleistocene was smaller than before and the master rivers of the Dalinhe River and the Xiaolinhe River transferred to west, so that the fan of the Dalinhe River and the Xiaolinhe River moved and incressed.Three times of transgression which were different in their extent occurred in the coastal area of the Liaodong Bay in Quaternary and marine formation and marine-continental formation devclopped in the area.The alternation of transgression and regression resulted in the changes of sedimentary environments and sedimentary facies.
