2004 Vol. 37 No. 3
Abstract：
The north area of Weihe River is located in the joint of the Qilian-North Qinling orogenic belt.Based on studying in detail of the petrology,contact relation,deformation,metamorphism and so on,the metamorphic granitoids can be recognized and brokenup from metamorphic terrane.The main diagenetic stage and relevant rock types are the Middle Proterozoic assemblage of gneissoid granodiorite-adamellite and the Sinian schistosity diorates.The important information about the tectonic environments was obtained obtained from the discrimination diagram.The Middle Proterozoic granitoids was an intraplate type producted in transitinal crystalline basement before plate collision.The Sinian granitoids are immediately related the plate collision,they were formed int he plate collision mounain-building period-post collision elevation period.The import ant evidence of plates collision of the granitoids are recorded between Qilian and North Qinlingin.
The north area of Weihe River is located in the joint of the Qilian-North Qinling orogenic belt.Based on studying in detail of the petrology,contact relation,deformation,metamorphism and so on,the metamorphic granitoids can be recognized and brokenup from metamorphic terrane.The main diagenetic stage and relevant rock types are the Middle Proterozoic assemblage of gneissoid granodiorite-adamellite and the Sinian schistosity diorates.The important information about the tectonic environments was obtained obtained from the discrimination diagram.The Middle Proterozoic granitoids was an intraplate type producted in transitinal crystalline basement before plate collision.The Sinian granitoids are immediately related the plate collision,they were formed int he plate collision mounain-building period-post collision elevation period.The import ant evidence of plates collision of the granitoids are recorded between Qilian and North Qinlingin.
Abstract：
Intrusive rocks of Longjishan-Shensheling,which distributed in Tianshuijing region in west of Inner Mongolia,have an elliptic shape toward northwest.Its area is more than 100 km2.They were named Longjishan Series,and included three units.The first unit is phenocryst bearing fine-grained biotite adamellite,the second is phenocryst bearing middle-fine grained biotite adamellite and the third is middle-fine grained granit.Granitoids enrich in SiO2 and Alk,contents of Alk vary between 7.23% and 8.37%,AKI are less than 1,ratios of A/CNK range from 1.01 to 1.07,and OX values vary betw een 0.47 and 0.83.The rocks enrich in LIL E and L REE,and deplete Ba,Nb,Sr,Zr and Ti relatively.REE patterns have distinct "V" type.Accessory mineral assem blages are Mt-Ap-Zi.Granit oids evolve twoard acidity and alkalinity from early unit to late unit,display the charact eristics of aluminous A-type granite(A2-type) and have the characteristic of post-orogeny in some tectonic setting distinguish diagram.U-Pbage of Zircon is 267.1 Ma.All of those indicated that the orog enic process occurred in Middle Permian,might end in late of Middle Permian and the tectonic setting might be shifted to the setting of interior plate in Late Permian.
Intrusive rocks of Longjishan-Shensheling,which distributed in Tianshuijing region in west of Inner Mongolia,have an elliptic shape toward northwest.Its area is more than 100 km2.They were named Longjishan Series,and included three units.The first unit is phenocryst bearing fine-grained biotite adamellite,the second is phenocryst bearing middle-fine grained biotite adamellite and the third is middle-fine grained granit.Granitoids enrich in SiO2 and Alk,contents of Alk vary between 7.23% and 8.37%,AKI are less than 1,ratios of A/CNK range from 1.01 to 1.07,and OX values vary betw een 0.47 and 0.83.The rocks enrich in LIL E and L REE,and deplete Ba,Nb,Sr,Zr and Ti relatively.REE patterns have distinct "V" type.Accessory mineral assem blages are Mt-Ap-Zi.Granit oids evolve twoard acidity and alkalinity from early unit to late unit,display the charact eristics of aluminous A-type granite(A2-type) and have the characteristic of post-orogeny in some tectonic setting distinguish diagram.U-Pbage of Zircon is 267.1 Ma.All of those indicated that the orog enic process occurred in Middle Permian,might end in late of Middle Permian and the tectonic setting might be shifted to the setting of interior plate in Late Permian.
2004, 37(3): 15-20.
Abstract：
The Xijir Ulan tectonic melange belt is the western part of Xijr Ulan-Jinshajiang sutural zone,because study in low degree in the past,it is still indefinite.After 1:250 000 regional surveys,study shows that the belt is comlex.It consists of basement,seabeach-sandstone,gabbro(diabase)dike swarm wall group,ophilite,silicalite,limestone(kop),flysch,and molasses.The ophiolite partly formed ocean ridge,mainly formed in an ocean island.Confined the Xijir Ulan tectonic melange belt consists of a sierise blocks seprated by thrust towards south.The evolution progress of the The Xijir Ulan tectonic melange belt is summarized primarily.
The Xijir Ulan tectonic melange belt is the western part of Xijr Ulan-Jinshajiang sutural zone,because study in low degree in the past,it is still indefinite.After 1:250 000 regional surveys,study shows that the belt is comlex.It consists of basement,seabeach-sandstone,gabbro(diabase)dike swarm wall group,ophilite,silicalite,limestone(kop),flysch,and molasses.The ophiolite partly formed ocean ridge,mainly formed in an ocean island.Confined the Xijir Ulan tectonic melange belt consists of a sierise blocks seprated by thrust towards south.The evolution progress of the The Xijir Ulan tectonic melange belt is summarized primarily.
Abstract：
The triphibian chipping-rock sedimentary formation in Early Cenozoic in Adatan basin in western segment of east Kunlun Mt.was formerly considered to belong to "Low Tertiary".In the 1:25 ten thousands Kelangmiqiti sheet of regional geology survey for the first time in the chipping-rock construct,the freshwater Gastropoda fossils were found:Australorbis pseudoammonius huanghoensis Yu,Lymnea sp.According to the stratum contained fossils lithofacies characteristics and the breatheable epoch of the Gastropoda fo ssils,someone considered that the"Low Tertiary" in Adatan basin should belong to the Low Ganchaigou Group of Oligocene in Ancient Neoteric period.According to the analysis of the presence of that stratum and the Early Pleistocene Qigequan Formation unconformably covered,the once stronger scale apophysis was oncluded in Adatanba sin in Oligocene.
The triphibian chipping-rock sedimentary formation in Early Cenozoic in Adatan basin in western segment of east Kunlun Mt.was formerly considered to belong to "Low Tertiary".In the 1:25 ten thousands Kelangmiqiti sheet of regional geology survey for the first time in the chipping-rock construct,the freshwater Gastropoda fossils were found:Australorbis pseudoammonius huanghoensis Yu,Lymnea sp.According to the stratum contained fossils lithofacies characteristics and the breatheable epoch of the Gastropoda fo ssils,someone considered that the"Low Tertiary" in Adatan basin should belong to the Low Ganchaigou Group of Oligocene in Ancient Neoteric period.According to the analysis of the presence of that stratum and the Early Pleistocene Qigequan Formation unconformably covered,the once stronger scale apophysis was oncluded in Adatanba sin in Oligocene.
2004, 37(3): 24-28.
Abstract：
The Radiolaria fossils are collected from siliceous gravel in conglomerate of Middle Devonian Sangejing Group in Dundunshan of Beishan area,Gansu province.The Radiolarians are identified primarily to be Inaniguttids,including two genus,the Inanigutta sp.and Inanibigutta sp.,which are primarily found in the strata of Ordovician-Silurian systems in the world,and Ordovician in North China.This discovery suggests silicalite containing Radiolaria of Lower Ordovician Shajing Group was been denuded,southward stransported and finally deposited in Dundun shan mola sses basin d ring the collision-orogenic period of Devonian in Beishan.Accordingly there existed collision-orogeney and amolasses basinin Devonian in Beishan area.
The Radiolaria fossils are collected from siliceous gravel in conglomerate of Middle Devonian Sangejing Group in Dundunshan of Beishan area,Gansu province.The Radiolarians are identified primarily to be Inaniguttids,including two genus,the Inanigutta sp.and Inanibigutta sp.,which are primarily found in the strata of Ordovician-Silurian systems in the world,and Ordovician in North China.This discovery suggests silicalite containing Radiolaria of Lower Ordovician Shajing Group was been denuded,southward stransported and finally deposited in Dundun shan mola sses basin d ring the collision-orogenic period of Devonian in Beishan.Accordingly there existed collision-orogeney and amolasses basinin Devonian in Beishan area.
Abstract：
Based on system study,Shaanxi matellogenic province can be divided into four belts belonging to I degree,four belts belonging to II degree,seven belts belonging to III degree,19 sub-belts belonging to IV degree and 44 sub-belts belong to V degree.
Based on system study,Shaanxi matellogenic province can be divided into four belts belonging to I degree,four belts belonging to II degree,seven belts belonging to III degree,19 sub-belts belonging to IV degree and 44 sub-belts belong to V degree.
2004, 37(3): 43-50.
Abstract：
Recent years,with prospecting for Cu deposit has got great success in the area adjacent of Inner Mongolia,as well as a series of important new evolvers in Cu ore prospects have got in Inner Mongolia,to prospect Cu deposit in Inner Mongolia has bringed the attentions of the geologists at home and abroad.The geological structure and Cu deposit explored and new information of geochemistry related to Cu deposit show that there are huge potentials for prospecting Cu deposit in this region.Analyzing and summ arizing the cha racteristics of distribution of Cu deposit and Cu abnorml,the authors make off three Cu ore-forming zones,circled Cu deposit or abnorml forestation furthe,and put forward the direction for prospecting large and ultralarge-scale Cudeposit.
Recent years,with prospecting for Cu deposit has got great success in the area adjacent of Inner Mongolia,as well as a series of important new evolvers in Cu ore prospects have got in Inner Mongolia,to prospect Cu deposit in Inner Mongolia has bringed the attentions of the geologists at home and abroad.The geological structure and Cu deposit explored and new information of geochemistry related to Cu deposit show that there are huge potentials for prospecting Cu deposit in this region.Analyzing and summ arizing the cha racteristics of distribution of Cu deposit and Cu abnorml,the authors make off three Cu ore-forming zones,circled Cu deposit or abnorml forestation furthe,and put forward the direction for prospecting large and ultralarge-scale Cudeposit.
Abstract：
By research of volcanic rock and mineralization,authous consider that the Cu,Ag deposits were related to felsic volcanic rock,quartz albitophyre immediately.The mineral deposit models of Cu,Ag in felsic volcanic rock of Permian continental facies have been summarized in times of ore-forming structural setting,ore-hosted environment,geological characteristics of the deposits and so on.
By research of volcanic rock and mineralization,authous consider that the Cu,Ag deposits were related to felsic volcanic rock,quartz albitophyre immediately.The mineral deposit models of Cu,Ag in felsic volcanic rock of Permian continental facies have been summarized in times of ore-forming structural setting,ore-hosted environment,geological characteristics of the deposits and so on.
Abstract：
On the basis of comprehensive analyzing metallogenic geological condition of explored mineral deposits in Fengxian-Taibai lead and zinc ore filed,it is considered that Qinjialiang and Guziliang two exploration target regions are very prospective to find new large-scale lead and zinc deposits,combined with exploration practice.However,Qinjialiang region have favorable ore-forming condition to prospect hydrothermal sedimentary typed lead and zinc deposits controlled by localized fault basin,and could find new new lead and zinc o re bod ies in the ta rget region by m ean s of lithofacies-geology mapping in 1:10000 scales and other survey work,and so on.But Guziliang region ha s the sam e m ineraliztion geological structure setting as Xicheng ore field,and should make geology mapping in 1:10000 scales to reduce region for prospcting and verifying.
On the basis of comprehensive analyzing metallogenic geological condition of explored mineral deposits in Fengxian-Taibai lead and zinc ore filed,it is considered that Qinjialiang and Guziliang two exploration target regions are very prospective to find new large-scale lead and zinc deposits,combined with exploration practice.However,Qinjialiang region have favorable ore-forming condition to prospect hydrothermal sedimentary typed lead and zinc deposits controlled by localized fault basin,and could find new new lead and zinc o re bod ies in the ta rget region by m ean s of lithofacies-geology mapping in 1:10000 scales and other survey work,and so on.But Guziliang region ha s the sam e m ineraliztion geological structure setting as Xicheng ore field,and should make geology mapping in 1:10000 scales to reduce region for prospcting and verifying.
2004, 37(3): 61-66.
Abstract：
Based on study of geological setting,ore-controlling tectonic,the paper probes into the geological characteristics and metallogenic mechanism of Xiajiadian gold deposit.The deposit occurs in the carbargillite-siliceous rock and ferroan carbonate rock of the Sinian-Cambrian system on the border of the Douling doming paleostructure in South Qinling.The tectonic system is become ore-control leading factor,this is manifold type and shape,varied nature,pulsution of many time of the tectonic activity.By study of relationship of structural analysis and mineralization-alteration has been set up remould met allogenic system of strat a control-shear and tension struct ure-hydr othermal convection.Xiajiadian gold deposit of like Carlin type is subjected to control of manifold control and reform of geological condition.
Based on study of geological setting,ore-controlling tectonic,the paper probes into the geological characteristics and metallogenic mechanism of Xiajiadian gold deposit.The deposit occurs in the carbargillite-siliceous rock and ferroan carbonate rock of the Sinian-Cambrian system on the border of the Douling doming paleostructure in South Qinling.The tectonic system is become ore-control leading factor,this is manifold type and shape,varied nature,pulsution of many time of the tectonic activity.By study of relationship of structural analysis and mineralization-alteration has been set up remould met allogenic system of strat a control-shear and tension struct ure-hydr othermal convection.Xiajiadian gold deposit of like Carlin type is subjected to control of manifold control and reform of geological condition.
Abstract：
The Southwest depression is a secondary structure in the Tarim basin,with an area of 1.225×105 square kilometers,and the main reservoir and production layer within Permo-Carboniferous strata.The major diagenesis of Carboniferous clastic rocks is mechanical compaction,cementation,replacement,dissolution and fracturing.Compaction and cementation resulted in poor reserveoir properties,but dissolution,particularly dissolution during deep burial,improved reservoir properties of clastic reservoirs.Crevice caused by fracturing lead to physical property better in reservoir to a certain extent.
The Southwest depression is a secondary structure in the Tarim basin,with an area of 1.225×105 square kilometers,and the main reservoir and production layer within Permo-Carboniferous strata.The major diagenesis of Carboniferous clastic rocks is mechanical compaction,cementation,replacement,dissolution and fracturing.Compaction and cementation resulted in poor reserveoir properties,but dissolution,particularly dissolution during deep burial,improved reservoir properties of clastic reservoirs.Crevice caused by fracturing lead to physical property better in reservoir to a certain extent.
2004, 37(3): 73-76.
Abstract：
In order to find industrial oil output standard to fit for the geology and reservoir engineering in Nanniwan oilfield.Based on the analogy and numerical value simulation,the results show that a well output still fit for the double decline curves after being fractured.To get an industrial oil output value,you must know the investment of a well,oil interest,the output value of reclaim a well etc.This value can fit for the production,calculate the reservoir,and roll development and the manager to make a strategic decision as well.
In order to find industrial oil output standard to fit for the geology and reservoir engineering in Nanniwan oilfield.Based on the analogy and numerical value simulation,the results show that a well output still fit for the double decline curves after being fractured.To get an industrial oil output value,you must know the investment of a well,oil interest,the output value of reclaim a well etc.This value can fit for the production,calculate the reservoir,and roll development and the manager to make a strategic decision as well.
2004, 37(3): 77-82.
Abstract：
On account of the complexities of mineralogical composition,structure and bond,the factors of leading to the variation of color are complicate.The color of a mineral is often the effect of many factors.Turquoise is a kind of jade that shows its own color,that is to say,the color of turquoise is determined by its own components and structures.Through microprobe analysis,the turquoise's components of distinct color are studied,and the result shows that turquoise's color is decided by Cu2+ ions and Fe3+ ions,the basic color of turquo ise is related tothe existence of Cu2+ octahed ron,whhis beneficia leffect,but Fe3+ ions lead to the reverse.The cry stal field and the spectrum experiment analysis getthe coincident conclu sion.The differential thermal analysis(DTA) and thermal analysis get the conclusion that some effects on the color of turquoise a recome in to being because of absorped water and cry stalline water:the more the absorped water contains,the deeper the color is.When it is heated to 300℃(turquoise loses a part of or the whole crysta lline),turquoise's color is changed obviou sly from blue to green.
On account of the complexities of mineralogical composition,structure and bond,the factors of leading to the variation of color are complicate.The color of a mineral is often the effect of many factors.Turquoise is a kind of jade that shows its own color,that is to say,the color of turquoise is determined by its own components and structures.Through microprobe analysis,the turquoise's components of distinct color are studied,and the result shows that turquoise's color is decided by Cu2+ ions and Fe3+ ions,the basic color of turquo ise is related tothe existence of Cu2+ octahed ron,whhis beneficia leffect,but Fe3+ ions lead to the reverse.The cry stal field and the spectrum experiment analysis getthe coincident conclu sion.The differential thermal analysis(DTA) and thermal analysis get the conclusion that some effects on the color of turquoise a recome in to being because of absorped water and cry stalline water:the more the absorped water contains,the deeper the color is.When it is heated to 300℃(turquoise loses a part of or the whole crysta lline),turquoise's color is changed obviou sly from blue to green.
2004, 37(3): 83-90.
Abstract：
After researches and analysis on status and trend of sandy desertification in Bashang area,the authors found that sandy desertification took a turn for the better in some areas,but it took a turn for the worse in overall situation.The degree of sandy desertification will be exacerbating unless some combating measures are put in effect; Through surveying the causes of sandy desertification and its development,we think that the natural basis of sandy desertification is climate changes,landforms,features of sediment and the condition of hydrology,and it simmediate cause is the unreasonable activities of human being.The harms of sandy desert ification in farming,stock raising,traffic,communication,water conserv ancy facilities and the health of human have been summ arized in this paper,and some measures and proposal on combating sandy desert ification have been put forward.
After researches and analysis on status and trend of sandy desertification in Bashang area,the authors found that sandy desertification took a turn for the better in some areas,but it took a turn for the worse in overall situation.The degree of sandy desertification will be exacerbating unless some combating measures are put in effect; Through surveying the causes of sandy desertification and its development,we think that the natural basis of sandy desertification is climate changes,landforms,features of sediment and the condition of hydrology,and it simmediate cause is the unreasonable activities of human being.The harms of sandy desert ification in farming,stock raising,traffic,communication,water conserv ancy facilities and the health of human have been summ arized in this paper,and some measures and proposal on combating sandy desert ification have been put forward.
Abstract：
As viewed from the hydrogeochemistry of Cretaceous groundwater in the south of Baiyu mountain of the Ordos basin,the article is focus on the groundwater horizontal distribution and the water chemistry about surface water base-flow.By combined with the geology structure frame and lithofacies paleo-geography,the authors study the recharge,runoff and discharge of the region.By analysis them,the authors can draw conclusions:the region has horizontal distribution of Cretaceous groundwater hydrogeochemistry from east and north and southwest to center.And the more complex the water quality is and the higher the TDS istoward the center of basin; the change of water quality in the Malian riverindicate that groundwater of the east and west side recharges the river.The authors consider that the east and the southwest area in the southern parts of Ordos basin is groundw ter recharge range,the center is discharge,the Tianhuan syncline and the Malian river valley is discharge passage.
As viewed from the hydrogeochemistry of Cretaceous groundwater in the south of Baiyu mountain of the Ordos basin,the article is focus on the groundwater horizontal distribution and the water chemistry about surface water base-flow.By combined with the geology structure frame and lithofacies paleo-geography,the authors study the recharge,runoff and discharge of the region.By analysis them,the authors can draw conclusions:the region has horizontal distribution of Cretaceous groundwater hydrogeochemistry from east and north and southwest to center.And the more complex the water quality is and the higher the TDS istoward the center of basin; the change of water quality in the Malian riverindicate that groundwater of the east and west side recharges the river.The authors consider that the east and the southwest area in the southern parts of Ordos basin is groundw ter recharge range,the center is discharge,the Tianhuan syncline and the Malian river valley is discharge passage.
2004, 37(3): 96-102.
Abstract：
The author presents the definition of the torrential floods,analyses on forming condition and influential factors of torrential floods hazards for Shaanxi province.From the temporal aspect of view,the torrential flood is of multiple terms and multiple occurring in the same term.It coincides with mud flows and land slides.Most torrential floods occur from July to September in every year and a few from April to June in every year.From the spatial aspect of view,it is characterized by concentration,controlling by rain storm centers and topography.Finally,the author presents the high-potential occurring zones of the to rrential floods and its precautions.
The author presents the definition of the torrential floods,analyses on forming condition and influential factors of torrential floods hazards for Shaanxi province.From the temporal aspect of view,the torrential flood is of multiple terms and multiple occurring in the same term.It coincides with mud flows and land slides.Most torrential floods occur from July to September in every year and a few from April to June in every year.From the spatial aspect of view,it is characterized by concentration,controlling by rain storm centers and topography.Finally,the author presents the high-potential occurring zones of the to rrential floods and its precautions.
2004, 37(3): 103-108.
Abstract：
The ophiolite geochronology is very important for the study of tectonic evolution of orogenic belt and the reconstruction of the ancient ocean-land and plate tectonic framework.The isotopic dating and fossil geochronometry are the basic methods of ophiolite geochronometry.U-Pb isotopic dating including single zircon U-Pb dating and SHRIMP zircon U-Pb dating is the first to be selected for the high precise isotopic dating.And Sm-Nd and Rb-Sr isochronal dating can be used to be assistant for it.The result of all these da ing methods and fossil geochronometry should be contrased each other.The sequence of some geological events related to the formation and evolution of ophiolite can give the rest riction on its geologic ages.This paper points that we must study the charact eristics of the dating objects in detail before daing of the ophiolite,and simult aneously know the applicability of various of dating methods and problems which should be at tended,thus we can draw the reasonable and scientific explanation to the signification and accuracy of dating results.
The ophiolite geochronology is very important for the study of tectonic evolution of orogenic belt and the reconstruction of the ancient ocean-land and plate tectonic framework.The isotopic dating and fossil geochronometry are the basic methods of ophiolite geochronometry.U-Pb isotopic dating including single zircon U-Pb dating and SHRIMP zircon U-Pb dating is the first to be selected for the high precise isotopic dating.And Sm-Nd and Rb-Sr isochronal dating can be used to be assistant for it.The result of all these da ing methods and fossil geochronometry should be contrased each other.The sequence of some geological events related to the formation and evolution of ophiolite can give the rest riction on its geologic ages.This paper points that we must study the charact eristics of the dating objects in detail before daing of the ophiolite,and simult aneously know the applicability of various of dating methods and problems which should be at tended,thus we can draw the reasonable and scientific explanation to the signification and accuracy of dating results.
