2010 Vol. 43 No. 1
2010, 43(1): 1-25.
Abstract：
Cenowic volcanign on the Tibetan plateau, which shows systematic variations in space and tine, is the volcanic response to the India-A sia continental collision. The volcanign gradually changed from Na-rich+K-rich to potassic-ultrapotassic+adakitic compo sitions along with the India-A sia collision shifting from contact-collisionof 65Ma (i. e,"soft collision") to all-sided collision of 45Ma (i. e,"hard collision". The sodium-rich and potassium-rich lavas with ages of 65~40 Ma distribute mainly in the Lhasa terrane of southern Tibet and subordinately in the Qiangtang terrane of central Tibet. The widespread potassic-ultrapotassic lavas and subordinate adakites were generated from~45 to 26 Ma in the Qiangtang terrane of central Tibet.
Cenowic volcanign on the Tibetan plateau, which shows systematic variations in space and tine, is the volcanic response to the India-A sia continental collision. The volcanign gradually changed from Na-rich+K-rich to potassic-ultrapotassic+adakitic compo sitions along with the India-A sia collision shifting from contact-collisionof 65Ma (i. e,"soft collision") to all-sided collision of 45Ma (i. e,"hard collision". The sodium-rich and potassium-rich lavas with ages of 65~40 Ma distribute mainly in the Lhasa terrane of southern Tibet and subordinately in the Qiangtang terrane of central Tibet. The widespread potassic-ultrapotassic lavas and subordinate adakites were generated from~45 to 26 Ma in the Qiangtang terrane of central Tibet.
2010, 43(1): 26-36.
Abstract：
This paper summarizes the assemblege of rock types and geochemical characteristics of four ophiolite belts in Beishan region, and analyzes the the regional geological background conditions. The result shows that the Hongliuhe-Niujuanzi-Xichangjing ophiolite belt was foamed in Early Palaeozoic and is part of the oceanic basin type and quite similar to the present oceanic ophiolite in characteristic. This ophiolite belt indicates the sutureline of the north-south plates because the Gongpoquan-dongqiyishan volcanic rocks in the north belongs to the inland volcanic rock series with active continental margin environment and the shallow sub-sea P-V-Mn-U-bearing sedinentary strata of the Cambrian in the south representing the extended tectonic before the plate becoming divergent.
This paper summarizes the assemblege of rock types and geochemical characteristics of four ophiolite belts in Beishan region, and analyzes the the regional geological background conditions. The result shows that the Hongliuhe-Niujuanzi-Xichangjing ophiolite belt was foamed in Early Palaeozoic and is part of the oceanic basin type and quite similar to the present oceanic ophiolite in characteristic. This ophiolite belt indicates the sutureline of the north-south plates because the Gongpoquan-dongqiyishan volcanic rocks in the north belongs to the inland volcanic rock series with active continental margin environment and the shallow sub-sea P-V-Mn-U-bearing sedinentary strata of the Cambrian in the south representing the extended tectonic before the plate becoming divergent.
Abstract：
The Xingditage Group in the Quruqtagh region of Xinjiang is considered as the Late Paleoproterozoic stratigrap by whose age is 2063.28Ma to 2321.4Ma from Pb isotopic dating. The carbon isotopic composition of marble of the Xinge'er Formation of Xingditage Group shows that its carbon iso topic composition ranges from 5.15‰ PDB to-0.79‰ PDB,and most carbon isotopic data distribute In 2‰ PDB,much different from δ13C carb composition (0‰~1‰ PDB)in early Middle Proterozoic(1 600 ~1 400Ma).
The Xingditage Group in the Quruqtagh region of Xinjiang is considered as the Late Paleoproterozoic stratigrap by whose age is 2063.28Ma to 2321.4Ma from Pb isotopic dating. The carbon isotopic composition of marble of the Xinge'er Formation of Xingditage Group shows that its carbon iso topic composition ranges from 5.15‰ PDB to-0.79‰ PDB,and most carbon isotopic data distribute In 2‰ PDB,much different from δ13C carb composition (0‰~1‰ PDB)in early Middle Proterozoic(1 600 ~1 400Ma).
2010, 43(1): 44-53.
Abstract：
The Supute gneiss complex is composed of andalusite,sillimanite,and cord ierite.It contains SiO2 ranging from 63.1% to 68.3%,Al2O3 from 13.64% to 15.91%,TiO2 from 0.53% to 0.77%,and relatively high MgO(mostly～3%).In line with their geochemical composition,they are metamorphized products of greywackes.For the trace elements,their total REE ranges from 155ppm to 272ppm and the LREE are enriched relative to the HREE with middle Eu negative anomalies.NASC normalized REE patterns of the Supute gneiss are coherently flat with insignificant Ce and Eu anomalies.Their geochemistry suggests that they are formed a long an active continental margin.Zircons from Supute gneiss show typical characteristics crystallized from magma and a SHR MIPU-Pb age of 282 Ma.Thus,the Supute gneiss represents an early Permian tectonomagmatic event.
The Supute gneiss complex is composed of andalusite,sillimanite,and cord ierite.It contains SiO2 ranging from 63.1% to 68.3%,Al2O3 from 13.64% to 15.91%,TiO2 from 0.53% to 0.77%,and relatively high MgO(mostly～3%).In line with their geochemical composition,they are metamorphized products of greywackes.For the trace elements,their total REE ranges from 155ppm to 272ppm and the LREE are enriched relative to the HREE with middle Eu negative anomalies.NASC normalized REE patterns of the Supute gneiss are coherently flat with insignificant Ce and Eu anomalies.Their geochemistry suggests that they are formed a long an active continental margin.Zircons from Supute gneiss show typical characteristics crystallized from magma and a SHR MIPU-Pb age of 282 Ma.Thus,the Supute gneiss represents an early Permian tectonomagmatic event.
Abstract：
The Xiang shan Group distributed in the middle part of the Ning xia Hui Autonomous Region has been divided into four unnamed subgroups.The occurrence of the trilobites Holocephalites punctatus Zhou, Olenoides ningxiacus Zhou,Peronopsis ovalis Zhou and conodonts Furnishina asymmetrica Müller,F. furnishi Müller from the thin-bedded limest one in its first subgroup suggests that the first subgroup of the Xiangshan Group ranges in age from the Middle to Late Cambrian.The conodonts Cordylodus proavus Müller and Oistodiform element recorded from the upper part of its second subgroup suggests that the subgroup is most likely of Late Cambrian to early Ordovician.However,the precise age of the whole Xiangshan Group is uncertain because its third and fourth subgroups are either poorly fossiliferous or no fossil srespectively.
The Xiang shan Group distributed in the middle part of the Ning xia Hui Autonomous Region has been divided into four unnamed subgroups.The occurrence of the trilobites Holocephalites punctatus Zhou, Olenoides ningxiacus Zhou,Peronopsis ovalis Zhou and conodonts Furnishina asymmetrica Müller,F. furnishi Müller from the thin-bedded limest one in its first subgroup suggests that the first subgroup of the Xiangshan Group ranges in age from the Middle to Late Cambrian.The conodonts Cordylodus proavus Müller and Oistodiform element recorded from the upper part of its second subgroup suggests that the subgroup is most likely of Late Cambrian to early Ordovician.However,the precise age of the whole Xiangshan Group is uncertain because its third and fourth subgroups are either poorly fossiliferous or no fossil srespectively.
2010, 43(1): 60-65.
Abstract：
Based on numerous actual data collected from long-time field investigation in source region of the Yangtze River and refering to the former research achievement,we analyzed the neotectonics movement characters in source region of the Yangtze River using the structural analysis.The results show that the tectonic motion has been very intensive in source region of the Yangtze River since the Quaternary period. Except for the vertical movement with integrity,differences,and periodical uplift,the Neotectonics Movement also shows a horizontal movement which experienced a period like Crustal shortening-nappe fold and fracture-block sliding.The whole tectonic movements shows both the successive revival and a certain reconstruction and regeneration.Overall,the Neotectonics Movement shaped the landform and Drainage pattern of source region of the Yangtze River.
Based on numerous actual data collected from long-time field investigation in source region of the Yangtze River and refering to the former research achievement,we analyzed the neotectonics movement characters in source region of the Yangtze River using the structural analysis.The results show that the tectonic motion has been very intensive in source region of the Yangtze River since the Quaternary period. Except for the vertical movement with integrity,differences,and periodical uplift,the Neotectonics Movement also shows a horizontal movement which experienced a period like Crustal shortening-nappe fold and fracture-block sliding.The whole tectonic movements shows both the successive revival and a certain reconstruction and regeneration.Overall,the Neotectonics Movement shaped the landform and Drainage pattern of source region of the Yangtze River.
Abstract：
The variation of geochemical element in section can reflect the paleoclimate circum stance in the course of sedimentary.Through systematically analyzing 30 pieces of samples collected from Duan jiapo section,we conclude that there is an obvious catastrophe point for every kinds of elements.Content of element has a great change from 0.57Ma to 0.37MaB.P,but keep unchanged around 0.37Ma. Paleoclimate have changed from the cold-warm fluctuation and total warmand moist to dry-cold climate from 0.57Ma to 0.37Ma B.P and from 0.37 Ma to 0.13Ma B.P and 0.13 Ma to 0.01Ma B.P,the change suggests that the variation trend of paleoclimate is from one geologicera to another. The result from element is not only identical to those from deep sea oxygen isotope,ancient vegetation,and paleoclimate but also consistent with MILAN KOV ITCH period.
The variation of geochemical element in section can reflect the paleoclimate circum stance in the course of sedimentary.Through systematically analyzing 30 pieces of samples collected from Duan jiapo section,we conclude that there is an obvious catastrophe point for every kinds of elements.Content of element has a great change from 0.57Ma to 0.37MaB.P,but keep unchanged around 0.37Ma. Paleoclimate have changed from the cold-warm fluctuation and total warmand moist to dry-cold climate from 0.57Ma to 0.37Ma B.P and from 0.37 Ma to 0.13Ma B.P and 0.13 Ma to 0.01Ma B.P,the change suggests that the variation trend of paleoclimate is from one geologicera to another. The result from element is not only identical to those from deep sea oxygen isotope,ancient vegetation,and paleoclimate but also consistent with MILAN KOV ITCH period.
Abstract：
In the southern margin Taibai rock-mass,the copper(molybdenum)ore has been found.There are 2 copper ore bodies,one copper-based body and 5 molybdenum mineralized bodies.The length of the Copper ore body is 245～445 m,with an average thickness of 2.03～2.81 m and an average grade of 1.57% to 1.67%.The length of molybdenum mineralized body is 50m,with a thickness of 2.03～2.81 and a grade of 0.01%～0.54%.The mineralizattion of copper-molybdenum is controlled by three factors: rock,structure,and alteration.We use the mining ore molybdenite Re-Os method to testiso topic age and obtain the age of 119.3～123.7 Ma for the copper-molybdenum mineralization in this area formed in the late Yanshan. In the southern margin Taibai rock-mass,the copper(molybdenum)ore has been found.There are 2 copper ore bodies,one copper-based body and 5 molybdenum mineralized bodies.The length of the Copper ore body is 245～445 m,with an average thickness of 2103～2181 mand an average grade of 1.57% to 1.67%.The length of molybdenum mineralized body is 50m,with a thickness of 2.03～2.81m and a grade of 0.01%～0.54%.The mineralizattion of copper-molybdenum is controlled by three factors: rock,structure,and alteration.We use the mining ore molybdenite Re-Os method to test isotopic age and obtain the age of 119.3～123.7 Ma for the copper-molybdenum mineralization in this area formed in the late Yanshan.
In the southern margin Taibai rock-mass,the copper(molybdenum)ore has been found.There are 2 copper ore bodies,one copper-based body and 5 molybdenum mineralized bodies.The length of the Copper ore body is 245～445 m,with an average thickness of 2.03～2.81 m and an average grade of 1.57% to 1.67%.The length of molybdenum mineralized body is 50m,with a thickness of 2.03～2.81 and a grade of 0.01%～0.54%.The mineralizattion of copper-molybdenum is controlled by three factors: rock,structure,and alteration.We use the mining ore molybdenite Re-Os method to testiso topic age and obtain the age of 119.3～123.7 Ma for the copper-molybdenum mineralization in this area formed in the late Yanshan. In the southern margin Taibai rock-mass,the copper(molybdenum)ore has been found.There are 2 copper ore bodies,one copper-based body and 5 molybdenum mineralized bodies.The length of the Copper ore body is 245～445 m,with an average thickness of 2103～2181 mand an average grade of 1.57% to 1.67%.The length of molybdenum mineralized body is 50m,with a thickness of 2.03～2.81m and a grade of 0.01%～0.54%.The mineralizattion of copper-molybdenum is controlled by three factors: rock,structure,and alteration.We use the mining ore molybdenite Re-Os method to test isotopic age and obtain the age of 119.3～123.7 Ma for the copper-molybdenum mineralization in this area formed in the late Yanshan.
Abstract：
Tungsten-tin deposits in Guposhan region is located in the southwest edge of Nanling metallogenic belt where is an important tungsten-tin producing area.There are three tungsten-tin ore fields:Xinlu,Shuiyanba,and Shanhu.the deposits are numerous in genetic type,of which the typical ones are tin-zincsul fide type,quartz veined tungsten type,and tungsten-tin quartz vein type.The researchers have done lots of researches on the diagenesis and mineralization in this region and believe that the W-Sn mineralization has a close relation with the fracture and the crust-mantle mixed granite in Guposhan region.
Tungsten-tin deposits in Guposhan region is located in the southwest edge of Nanling metallogenic belt where is an important tungsten-tin producing area.There are three tungsten-tin ore fields:Xinlu,Shuiyanba,and Shanhu.the deposits are numerous in genetic type,of which the typical ones are tin-zincsul fide type,quartz veined tungsten type,and tungsten-tin quartz vein type.The researchers have done lots of researches on the diagenesis and mineralization in this region and believe that the W-Sn mineralization has a close relation with the fracture and the crust-mantle mixed granite in Guposhan region.
Abstract：
Based on analyzing the combination of geochemical indicators,the affecting degree of factors,the regional geochemical change,and the relationship between oil and gas,we establish the methods and effective combination of indica to rseries to search on natural gas exploration in Hang jinqi area of Ordos basin so as to analyze the region background and the preference of anomalies.The analysis of regional geochemical backg round,geochemical indicators high lighted in the law of space distribution reveals the abnormal and the intrinsic link between oil and gas,pointing out that the geochemical indicators of oil and gas abundance and low variability of the background belongs to the scope of non-uniform field;for the differentiation characteristics of hydrocarbons,the geochemical fieldin this area has the characteristics of the North-South Division:The hydrocarbons mainly come by the way of micro leakage in the south areas, in the north areas,the hydrocarbons gradually transit to the macro leakage.This indicates that the geochemical fieldis closely related to migration and accumulation of oil and also confirms that there is a more adequate gas source in this area.
Based on analyzing the combination of geochemical indicators,the affecting degree of factors,the regional geochemical change,and the relationship between oil and gas,we establish the methods and effective combination of indica to rseries to search on natural gas exploration in Hang jinqi area of Ordos basin so as to analyze the region background and the preference of anomalies.The analysis of regional geochemical backg round,geochemical indicators high lighted in the law of space distribution reveals the abnormal and the intrinsic link between oil and gas,pointing out that the geochemical indicators of oil and gas abundance and low variability of the background belongs to the scope of non-uniform field;for the differentiation characteristics of hydrocarbons,the geochemical fieldin this area has the characteristics of the North-South Division:The hydrocarbons mainly come by the way of micro leakage in the south areas, in the north areas,the hydrocarbons gradually transit to the macro leakage.This indicates that the geochemical fieldis closely related to migration and accumulation of oil and also confirms that there is a more adequate gas source in this area.
Abstract：
Lower Ordo vician Majiagou formation Ma-6 section distributes abroadly along the southern margin of Ordos Basin,its thichness increases gradually from north to south,mainly consists of algal limest one,patchy limest one,powder crystal dolomite,and grained dolomite.Based on the geotectonic background of the southern margin of the North China plat form of the lower Ordovician,the sedimentary environments and sedimentary patterns of Majiagou Formation are analyzed and the reservoir-forming factors and their space arrangement researched according to out crop section,downhole core data,and lithologic combination features.The result shows that the reef flat facies deposition is developed in some parts of the Majiagou Formation and form dolomite reservoirs through later diagenesis and dolomitisation. These dolomite reservoirs and neighboring muddy intervals form reservoir-forming combination of up generation and down reservoirs,and have a good exploration potential.
Lower Ordo vician Majiagou formation Ma-6 section distributes abroadly along the southern margin of Ordos Basin,its thichness increases gradually from north to south,mainly consists of algal limest one,patchy limest one,powder crystal dolomite,and grained dolomite.Based on the geotectonic background of the southern margin of the North China plat form of the lower Ordovician,the sedimentary environments and sedimentary patterns of Majiagou Formation are analyzed and the reservoir-forming factors and their space arrangement researched according to out crop section,downhole core data,and lithologic combination features.The result shows that the reef flat facies deposition is developed in some parts of the Majiagou Formation and form dolomite reservoirs through later diagenesis and dolomitisation. These dolomite reservoirs and neighboring muddy intervals form reservoir-forming combination of up generation and down reservoirs,and have a good exploration potential.
2010, 43(1): 115-123.
Abstract：
Yuejin No.2 oil reservoir includes three main oil groups:Xiayou shashan Formation(N21), Shangganchaigou Formation(N1),and the lower part of Xiaganchaigou Formation(E31)For a long period of time,it has been considered to be a general braided river delta,with the main types of sand stone being distributary channel,mouth bar,and sand sheet.In our study,through the core observation,log-phase analysis,and in accordance with the sediment grain size,sand body,and the spatial distribution patterns of modern riversediment type,the deposition background of the districtis still braided river delta,but the sedimentary microfacies types and causes of sand body model are different from the general braided river delta,which is that the skeleton of sand body is characterized by diversion dams,diverting rivers,and estuaries due to dam development.
Yuejin No.2 oil reservoir includes three main oil groups:Xiayou shashan Formation(N21), Shangganchaigou Formation(N1),and the lower part of Xiaganchaigou Formation(E31)For a long period of time,it has been considered to be a general braided river delta,with the main types of sand stone being distributary channel,mouth bar,and sand sheet.In our study,through the core observation,log-phase analysis,and in accordance with the sediment grain size,sand body,and the spatial distribution patterns of modern riversediment type,the deposition background of the districtis still braided river delta,but the sedimentary microfacies types and causes of sand body model are different from the general braided river delta,which is that the skeleton of sand body is characterized by diversion dams,diverting rivers,and estuaries due to dam development.
Abstract：
The main body of Chang-6 reservoir in Huaqing region is delta deposition,with the lithology being mainly the fine sand stone.Four-property relation of target section in the region were studied by thin section,mercury penetration,logging,showing that①Chang-6 reservoir in the region belongs to typical low-porosity and low-permeanbility oil interval,②diversity between lithology and physical property controls the enrichment of the reservoir,and ③cut-off properties standard are thus determined with a porosity of 8% and a permeanbiliy of 0.08×10-3μm2,and ③the lower limit of electrical property is determined to be 16Ω·m and the acoustic time to be 215μs/m.
The main body of Chang-6 reservoir in Huaqing region is delta deposition,with the lithology being mainly the fine sand stone.Four-property relation of target section in the region were studied by thin section,mercury penetration,logging,showing that①Chang-6 reservoir in the region belongs to typical low-porosity and low-permeanbility oil interval,②diversity between lithology and physical property controls the enrichment of the reservoir,and ③cut-off properties standard are thus determined with a porosity of 8% and a permeanbiliy of 0.08×10-3μm2,and ③the lower limit of electrical property is determined to be 16Ω·m and the acoustic time to be 215μs/m.
2010, 43(1): 130-136.
Abstract：
In this paper,we study and analyzethe characteristics of debris flow in Dongchuan copper mining area by field survey and discuss the cause of debris flow from landform,geological structure,climate, hydrology,vegetation,and human factors such as a long-time exploiting,engineering activities, unrea sonable engineering activities so as to understand the mechanism of forminig debris flow,raise people's awareness of preventing and harnessing the debris flow,and achieve the purpose of preventing and reducing the disaster of debris flow.
In this paper,we study and analyzethe characteristics of debris flow in Dongchuan copper mining area by field survey and discuss the cause of debris flow from landform,geological structure,climate, hydrology,vegetation,and human factors such as a long-time exploiting,engineering activities, unrea sonable engineering activities so as to understand the mechanism of forminig debris flow,raise people's awareness of preventing and harnessing the debris flow,and achieve the purpose of preventing and reducing the disaster of debris flow.
Abstract：
Using the opportunity of basic eco-geological environment survey data from the source region of Yangtze River,we propose an index system of eco-geological environment for this region by adopting the analytic hierarchy process(AHP)model and finally delineates the regional eco-geo-environmental quality indexes.These make a quantitative analysis of eco-geological environmental changes of this source region area from a brand new point on the qualita tive basis,indicating that the main factor affecting the ecological environment in this area is the change in environment of animals and plants,further more,this fact reveals the future development trend of the eco-geological environment of this area,resulting in a more objective and more accurate evaluation about environmental quality and rational development of the region.
Using the opportunity of basic eco-geological environment survey data from the source region of Yangtze River,we propose an index system of eco-geological environment for this region by adopting the analytic hierarchy process(AHP)model and finally delineates the regional eco-geo-environmental quality indexes.These make a quantitative analysis of eco-geological environmental changes of this source region area from a brand new point on the qualita tive basis,indicating that the main factor affecting the ecological environment in this area is the change in environment of animals and plants,further more,this fact reveals the future development trend of the eco-geological environment of this area,resulting in a more objective and more accurate evaluation about environmental quality and rational development of the region.
