The Shaxi porphyry copper (gold) deposits are a typical example of porphyry copper deposits associated with diorite in eastern China. Quartz diorite, which hosts the deposits, has a Rb-Sr isochron age of 127.9 ± ...The Shaxi porphyry copper (gold) deposits are a typical example of porphyry copper deposits associated with diorite in eastern China. Quartz diorite, which hosts the deposits, has a Rb-Sr isochron age of 127.9 ± 1.6 Ma. Geochemically, the rock is rich in alkalis (especially sodium), light rare earth elements (LREE) and large-ion lithophile elements (LILE), and has a relatively low initial strontium isotopic ratio (Isr=0.7058); thus it is the product of differentiation of crust-mantle mixing source magma. The model of alteration and mineralization zoning is similar to the Hollister (1974) diorite model. The ore fluids have a relatively high salinity and contain significant amounts of CO2, Ca2+, Na+ and ***CI?. The homogenization temperatures of fluid inclusions for the main mineralization stage range from 280 to 420°C, the δ18O values of the ore fluids vary from 3.51 to 5.52 %, the δD values are in the range between ?82.4 and ?59.8 %, the δ34S values of sulphides vary from ?0.3 to 2.49 %, and the δ13C values of CO2 in inclusions range between ?2.66 and ?6.53 %. Isotope data indicate that the hydrothermal ore fluids and ore substances of the Shaxi porphyry copper (gold) deposits were mainly derived from magmatic systems.展开更多
1 Introduction The early formation and evolution of the North China craton has been widely concerned by scientists.The Bengbu uplift belt is located in the southeast of the craton,theresearch degree of the belt is rel...1 Introduction The early formation and evolution of the North China craton has been widely concerned by scientists.The Bengbu uplift belt is located in the southeast of the craton,theresearch degree of the belt is relatively low and received increasing attention from many scholars in recent years.Through the author’s practical work and combined with展开更多
1 Introduction Santanghu Basin is located between the Armantai and Karamaili suture zone,at the junction of the Siberia,Kazakhstan and Tarim plates(Chen and Jahn,2004;Xiao et al.,2008).As an important part of the Cent...1 Introduction Santanghu Basin is located between the Armantai and Karamaili suture zone,at the junction of the Siberia,Kazakhstan and Tarim plates(Chen and Jahn,2004;Xiao et al.,2008).As an important part of the Central Asian展开更多
The Wenquan molybdenum deposit is a kind of large-sized porphyry molybdenum deposit found in re-cent years.In this paper,on the basis of deposit geology,geochemistry and isotope geochronology data,the metal-logenic mo...The Wenquan molybdenum deposit is a kind of large-sized porphyry molybdenum deposit found in re-cent years.In this paper,on the basis of deposit geology,geochemistry and isotope geochronology data,the metal-logenic model of this deposit was established.The Wenquan granitic batholith belongs to the K-rich(alkali-rich) calc-alkaline rock series,which is the mineralization parent rock.The rock massif shows the characteristics of both crust-remelting granite and mantle-source granite.At the same time,the data of REE contents,hydrogen and oxygen isotopes and inclusion temperatures showed that the metallogenic hydrothermal solution is a mixed mesothermal solution of magmato-hydrothermal fluid and meteoric water.Mineralization was dated at 214±7.1 Ma,basically identical with the parent rock's age(207-226 Ma).This reflects that molybdenum mineralization has a close relation to tectonic magmatism evoked by orogenic processes,and molybdenum mineralization occurred mainly at the petrogenesis stage at the late stage of magma emplacement.Mixing with meteoric water led to a decrease in the sa-linity of magmato-hydrothermal solution and changes in other physical and chemical properties.During the tectonic process,ore-bearing hydrothermal solution ascended along favorable fault structure channels.With physicochemical changes,it filled in the surrounding rock joints on both sides of faults,forming ore deposits.展开更多
Jiaojiang sag in the East China Sea Basin is at the earlier exploration stage,where characterizing hydrocarbon generation of source rocks is important to understand oil-gas exploration potential.Utilizing geochemical ...Jiaojiang sag in the East China Sea Basin is at the earlier exploration stage,where characterizing hydrocarbon generation of source rocks is important to understand oil-gas exploration potential.Utilizing geochemical and basin modeling analysis,hydrocarbon generation capacity and process of the Paleocene E_(1)y,E_(1)l and E_(1)m formations were investigated.Results show that E_(1)y and E_(1)l mudstones are high-quality source rocks with Type Ⅱ kerogen,which is dominated by both aquatic organisms and terrestrial higher plants deposited in sub-reduced environment.E_(1)m mudstone interbedded with thin carbonaceous mudstone and coal is poor-quality source rock with Type Ⅲ kerogen,whose organic matter was originated from terrestrial higher plants under oxidized environment.Controlled by burial and maturity histories,E_(1)y and E_(1)l source rocks experienced two hydrocarbon generation stages,which took place in the Late Paleocene and in the Middle to Late Eocene,respectively,and had high hydrocarbon generation capacity with cumulative hydrocarbon volume of 363 and 328 mg/g,respectively.E_(1)m source rock only had one hydrocarbon generation process in the Late Eocene,which had low hydrocarbon generation capacity with cumulative hydrocarbon volume of only 24 mg/g.The future oil-gas exploration in the Jiaojiang sag should focus on hydrocarbon generation center and select targets in the central uplift formed before the Miocene with high-quality traps.展开更多
Tanzania is located in eastern Africa with a predominantly agricultural ecomomy,the potential for developing and utilizing cultivated land are promising,but scientific guidance is required.B,Zn and Se are essential mi...Tanzania is located in eastern Africa with a predominantly agricultural ecomomy,the potential for developing and utilizing cultivated land are promising,but scientific guidance is required.B,Zn and Se are essential micronutrients for plants and human body with crucial biological functions,in particular,Se is significant for human health and considered as“the king of anti-cancer”.As these elements required by human or plants are mainly absorbed from soil directly or indirectly,therefore,it is important to understand the contents and distributions of them in the soil of cultivated land for guiding agricultural production.In this work,low-density geochemical survey at the scale of 1∶1000000 was carried out in Tanzania,and the results show that the concentrations of B,Zn and Se in stream sediments are low and their distributions are heterogeneous.According to the distributions of geological units,the existing cultivated land resources can be divided into five regions in Tanzania.Compared with the national background values,the concentrations of B,Zn and Se are insufficient overall but enriched locally in these regions.In general,element concentrations in stream sediments and soil have a positive correlation because of their similar sources,which is essential in agriculture application.Based on the information provided by low-density geochemical data and maps,the Se-sufficient and Se-rich regions were delineated in Tanzania,where can be used to develop Se-rich industries.Finally,this paper believes that geochemical survey is a powerful tool for cultivated land evaluation,agriculture management and land development.展开更多
Due to limited data on the geochemical properties of natural gas,estimations are needed for the effective gas source rock in evaluating gas potential.However,the pronounced heterogeneity of mudstones in lacustrine suc...Due to limited data on the geochemical properties of natural gas,estimations are needed for the effective gas source rock in evaluating gas potential.However,the pronounced heterogeneity of mudstones in lacustrine successions complicates the prediction of the presence and geochemical characteristics of gas source rocks.In this paper,the Liaohe Subbasin of Northeast China is used as an example to construct a practical methodology for locating effective gas source rocks in typical lacustrine basins.Three types of gas source rocks,microbial,oil-type,and coal-type,were distinguished according to the different genetic types of their natural gas.A practical three-dimensional geological model was developed,refined,and applied to determine the spatial distribution of the mudstones in the Western Depression of the Liaohe Subbasin and to describe the geochemical characteristics(the abundance,type,and maturation levels of the organic matter).Application of the model in the subbasin indicates that the sedimentary facies have led to heterogeneity in the mudstones,particularly with respect to organic matter types.The effective gas source rock model constructed for the Western Depression shows that the upper sequence(SQ2)of the Fourth member(Mbr 4)of the Eocene Shahejie Formation(Fm)and the lower and middle sequences(SQ3 and SQ4)of the Third member(Mbr 3)form the principal gas-generating interval.The total volume of effective gas source rocks is estimated to be 586 km^(3).The effective microbial,oil-type,and coal-type gas source rocks are primarily found in the shallow western slope,the central sags,and the eastern slope of the Western Depression,respectively.This study provides a practical approach for more accurately identifying the occurrence and geochemical characteristics of effective natural gas source rocks,enabling a precise quantitative estimation of natural gas reserves.展开更多
Coal seams can enrich a variety of harmful trace elements under specific geological conditions.The spatial distribution of harmful trace elements in coal is extremely uneven,and the distribution characteristics of eac...Coal seams can enrich a variety of harmful trace elements under specific geological conditions.The spatial distribution of harmful trace elements in coal is extremely uneven,and the distribution characteristics of each element content are different.The harmful elements released in the process of coal mining and utilization will cause serious harm to the environment and the human body.It is of great resource significance to study the geochemistry of coal that affects the enrichment and distribution characteristics of harmful trace elements.Based on the domestic and foreign literature on coal geochemistry in Guizhou published by previous investigators,this study counted 1097 sample data from 23 major coal-producing counties in Guizhou Province,systematically summarized the relevant research results of harmful trace elements in the coal of Guizhou,and revealed the overall distribution and enrichment characteristics of harmful trace elements in the coal of Guizhou.The results show that the average contents of Cd,Pb,Se,Cu,Mo,U,V,As,Hg,and Cr in coal of Guizhou are higher than those in Chinese coal and world coal.A variety of harmful trace elements in the coal of Guizhou have high background values,especially in Liupanshui,Xingyi and Qianbei coalfield.The enrichment of various harmful trace elements in the Late Permian coal in Guizhou is mainly related to the combined action of various geological and geochemical factors.The supply of terrigenous debris and sedimentary environment may be the basic background of the enrichment of harmful elements in western Guizhou,while low-temperature hydrothermal activity and volcanic ash deposition may be the main reasons for the enrichment of harmful elements in southwestern Guizhou.展开更多
文摘The Shaxi porphyry copper (gold) deposits are a typical example of porphyry copper deposits associated with diorite in eastern China. Quartz diorite, which hosts the deposits, has a Rb-Sr isochron age of 127.9 ± 1.6 Ma. Geochemically, the rock is rich in alkalis (especially sodium), light rare earth elements (LREE) and large-ion lithophile elements (LILE), and has a relatively low initial strontium isotopic ratio (Isr=0.7058); thus it is the product of differentiation of crust-mantle mixing source magma. The model of alteration and mineralization zoning is similar to the Hollister (1974) diorite model. The ore fluids have a relatively high salinity and contain significant amounts of CO2, Ca2+, Na+ and ***CI?. The homogenization temperatures of fluid inclusions for the main mineralization stage range from 280 to 420°C, the δ18O values of the ore fluids vary from 3.51 to 5.52 %, the δD values are in the range between ?82.4 and ?59.8 %, the δ34S values of sulphides vary from ?0.3 to 2.49 %, and the δ13C values of CO2 in inclusions range between ?2.66 and ?6.53 %. Isotope data indicate that the hydrothermal ore fluids and ore substances of the Shaxi porphyry copper (gold) deposits were mainly derived from magmatic systems.
基金the project "A study on gold mineralization and prospecting direction in east Anhui province" (item code: 2014-K-5)
文摘1 Introduction The early formation and evolution of the North China craton has been widely concerned by scientists.The Bengbu uplift belt is located in the southeast of the craton,theresearch degree of the belt is relatively low and received increasing attention from many scholars in recent years.Through the author’s practical work and combined with
文摘1 Introduction Santanghu Basin is located between the Armantai and Karamaili suture zone,at the junction of the Siberia,Kazakhstan and Tarim plates(Chen and Jahn,2004;Xiao et al.,2008).As an important part of the Central Asian
文摘The Wenquan molybdenum deposit is a kind of large-sized porphyry molybdenum deposit found in re-cent years.In this paper,on the basis of deposit geology,geochemistry and isotope geochronology data,the metal-logenic model of this deposit was established.The Wenquan granitic batholith belongs to the K-rich(alkali-rich) calc-alkaline rock series,which is the mineralization parent rock.The rock massif shows the characteristics of both crust-remelting granite and mantle-source granite.At the same time,the data of REE contents,hydrogen and oxygen isotopes and inclusion temperatures showed that the metallogenic hydrothermal solution is a mixed mesothermal solution of magmato-hydrothermal fluid and meteoric water.Mineralization was dated at 214±7.1 Ma,basically identical with the parent rock's age(207-226 Ma).This reflects that molybdenum mineralization has a close relation to tectonic magmatism evoked by orogenic processes,and molybdenum mineralization occurred mainly at the petrogenesis stage at the late stage of magma emplacement.Mixing with meteoric water led to a decrease in the sa-linity of magmato-hydrothermal solution and changes in other physical and chemical properties.During the tectonic process,ore-bearing hydrothermal solution ascended along favorable fault structure channels.With physicochemical changes,it filled in the surrounding rock joints on both sides of faults,forming ore deposits.
基金supported by the China National Science and Technology Major Project(Nos.2016ZX05024-002-003,2017ZX05032-001-004)the Foundation of Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education(China University of Geosciences),China(Nos.TPR-2022-11,TPR-2022-24)the Science and Technology Planning Project of Tangshan City,China(Nos.22130213H).
文摘Jiaojiang sag in the East China Sea Basin is at the earlier exploration stage,where characterizing hydrocarbon generation of source rocks is important to understand oil-gas exploration potential.Utilizing geochemical and basin modeling analysis,hydrocarbon generation capacity and process of the Paleocene E_(1)y,E_(1)l and E_(1)m formations were investigated.Results show that E_(1)y and E_(1)l mudstones are high-quality source rocks with Type Ⅱ kerogen,which is dominated by both aquatic organisms and terrestrial higher plants deposited in sub-reduced environment.E_(1)m mudstone interbedded with thin carbonaceous mudstone and coal is poor-quality source rock with Type Ⅲ kerogen,whose organic matter was originated from terrestrial higher plants under oxidized environment.Controlled by burial and maturity histories,E_(1)y and E_(1)l source rocks experienced two hydrocarbon generation stages,which took place in the Late Paleocene and in the Middle to Late Eocene,respectively,and had high hydrocarbon generation capacity with cumulative hydrocarbon volume of 363 and 328 mg/g,respectively.E_(1)m source rock only had one hydrocarbon generation process in the Late Eocene,which had low hydrocarbon generation capacity with cumulative hydrocarbon volume of only 24 mg/g.The future oil-gas exploration in the Jiaojiang sag should focus on hydrocarbon generation center and select targets in the central uplift formed before the Miocene with high-quality traps.
基金the cooperation projects between China Geological Survey and geological survey institutions of Africa(DD20190439,DD20160108,DD20221801)。
文摘Tanzania is located in eastern Africa with a predominantly agricultural ecomomy,the potential for developing and utilizing cultivated land are promising,but scientific guidance is required.B,Zn and Se are essential micronutrients for plants and human body with crucial biological functions,in particular,Se is significant for human health and considered as“the king of anti-cancer”.As these elements required by human or plants are mainly absorbed from soil directly or indirectly,therefore,it is important to understand the contents and distributions of them in the soil of cultivated land for guiding agricultural production.In this work,low-density geochemical survey at the scale of 1∶1000000 was carried out in Tanzania,and the results show that the concentrations of B,Zn and Se in stream sediments are low and their distributions are heterogeneous.According to the distributions of geological units,the existing cultivated land resources can be divided into five regions in Tanzania.Compared with the national background values,the concentrations of B,Zn and Se are insufficient overall but enriched locally in these regions.In general,element concentrations in stream sediments and soil have a positive correlation because of their similar sources,which is essential in agriculture application.Based on the information provided by low-density geochemical data and maps,the Se-sufficient and Se-rich regions were delineated in Tanzania,where can be used to develop Se-rich industries.Finally,this paper believes that geochemical survey is a powerful tool for cultivated land evaluation,agriculture management and land development.
文摘Due to limited data on the geochemical properties of natural gas,estimations are needed for the effective gas source rock in evaluating gas potential.However,the pronounced heterogeneity of mudstones in lacustrine successions complicates the prediction of the presence and geochemical characteristics of gas source rocks.In this paper,the Liaohe Subbasin of Northeast China is used as an example to construct a practical methodology for locating effective gas source rocks in typical lacustrine basins.Three types of gas source rocks,microbial,oil-type,and coal-type,were distinguished according to the different genetic types of their natural gas.A practical three-dimensional geological model was developed,refined,and applied to determine the spatial distribution of the mudstones in the Western Depression of the Liaohe Subbasin and to describe the geochemical characteristics(the abundance,type,and maturation levels of the organic matter).Application of the model in the subbasin indicates that the sedimentary facies have led to heterogeneity in the mudstones,particularly with respect to organic matter types.The effective gas source rock model constructed for the Western Depression shows that the upper sequence(SQ2)of the Fourth member(Mbr 4)of the Eocene Shahejie Formation(Fm)and the lower and middle sequences(SQ3 and SQ4)of the Third member(Mbr 3)form the principal gas-generating interval.The total volume of effective gas source rocks is estimated to be 586 km^(3).The effective microbial,oil-type,and coal-type gas source rocks are primarily found in the shallow western slope,the central sags,and the eastern slope of the Western Depression,respectively.This study provides a practical approach for more accurately identifying the occurrence and geochemical characteristics of effective natural gas source rocks,enabling a precise quantitative estimation of natural gas reserves.
基金supported by National Natural Science Foundation of China(No.51964009)。
文摘Coal seams can enrich a variety of harmful trace elements under specific geological conditions.The spatial distribution of harmful trace elements in coal is extremely uneven,and the distribution characteristics of each element content are different.The harmful elements released in the process of coal mining and utilization will cause serious harm to the environment and the human body.It is of great resource significance to study the geochemistry of coal that affects the enrichment and distribution characteristics of harmful trace elements.Based on the domestic and foreign literature on coal geochemistry in Guizhou published by previous investigators,this study counted 1097 sample data from 23 major coal-producing counties in Guizhou Province,systematically summarized the relevant research results of harmful trace elements in the coal of Guizhou,and revealed the overall distribution and enrichment characteristics of harmful trace elements in the coal of Guizhou.The results show that the average contents of Cd,Pb,Se,Cu,Mo,U,V,As,Hg,and Cr in coal of Guizhou are higher than those in Chinese coal and world coal.A variety of harmful trace elements in the coal of Guizhou have high background values,especially in Liupanshui,Xingyi and Qianbei coalfield.The enrichment of various harmful trace elements in the Late Permian coal in Guizhou is mainly related to the combined action of various geological and geochemical factors.The supply of terrigenous debris and sedimentary environment may be the basic background of the enrichment of harmful elements in western Guizhou,while low-temperature hydrothermal activity and volcanic ash deposition may be the main reasons for the enrichment of harmful elements in southwestern Guizhou.
