The Yingshan Formation of the Lower-Middle Ordovician in the Tarim Basin(NW China)was mainly deposited in a shallow platform,which was intensely bioturbated with burrows filled with both dolomites and calcites.This st...The Yingshan Formation of the Lower-Middle Ordovician in the Tarim Basin(NW China)was mainly deposited in a shallow platform,which was intensely bioturbated with burrows filled with both dolomites and calcites.This study aims to figure out the controls on the dolomitization of burrow infills and the effects on petroleum reservoir quality based on petrographic examination,fluid inclusion microthermometry,and isotopic(C-O-Sr)geochemical analyses.The differentiation of burrow-associated carbonates(dolomites and calcites)was likely controlled by the interactions of sea-level oscillations of variable orders and depositional environments.The burrow-associated dolomites(BADs)were precipitated in a relatively restricted(i.e.,lagoon)depositional environment during the lowstand of long-term sea level.In contrast,the burrow-associated calcites(BACs)were formed in a water circulation-improved lagoonal environment during the transgression of long-term sea level.Isotopic geochemical data indicate that the BADs in the Yingshan Formation were formed from slightly saline(i.e.,mesosaline to penesaline)seawater,whereas the BACs were precipitated from nearly normal seawater.In addition to the anoxic condition,the presence of marine-sourced organic matter and sulfate-reducing bacteria,and a sufficient supply of dolomitizing fluids enriched in magnesium ions(Mg^(2+))and their Mg^(2+)concentration may have played a critical role in the formation of BADs.In the more permeable and disturbed burrow sediments as a result of burrowing,penetrating fluids with higher salinities and higher Mg^(2+)concentration relative to seawater favored dolomite precipitation.The fluids with seawater-like Mg^(2+)concentration,however,would lead to calcite precipitation.The progressive dolomitization of these burrowed sediments could have propagated the dolomitizing fronts and extended into ambient limestones,leading to the development of extensive dolomites.This dolomitization process can improve the petrophysical properties(porosity and permeability)and the potential as hydrocarbon reservoirs during the emplacement of hydrocarbons from underlying source rocks of the Cambrian to Lower Ordovician.展开更多
The detrital modes of the sandstones from the south basin of Dabie（大别） orogenic belt during the Early-Middle Jurassic are complex due to multiple supplying.Detrital compositions of medium-coarse sandstones from th...The detrital modes of the sandstones from the south basin of Dabie（大别） orogenic belt during the Early-Middle Jurassic are complex due to multiple supplying.Detrital compositions of medium-coarse sandstones from the Lower-Middle Jurassic,Huangshi（黄石）,show three main provenances：recycled ororgen,volcanic arc（arc orogen）,and continental block on the bases of the Dickinson discriminating diagrams of modal composition and analysis of sandstone petrofacies.Combined with sparse published paleocurrent data,geotectonic setting of the study area,and the unpublished detrital zircon age data,the positions of the main provenances are inferred as follows：coastal orogenic belt（COB） in the East China provided detritus as the recycled orogen provenance;Dabie orogenic belt（DOB） to the north was the source of volcanic arc（arc orogen） materials;and the continental block clasts were likely from the uplift of the Yangtze basement（UYB）（Jiangnan（江南） uplift）.Six sedimentary cycles are recognized in the studied section,one in Wuchang（武昌） Formation,and five in Huajiahu（花家湖） Formation.During the deposition,the three main provenances play different roles.The quantitative petrofacies analysis revealed distinct changes of the effect from each source,that is,61.9%（Cycle Ⅰ）→54.5%（Cycle Ⅲ）→50%（Cycle Ⅳ）→57.9%（Cycle Ⅴ）→14.3%（Cycle Ⅵ）,14.3%（Cycle Ⅰ）→21.2%（ Cycle Ⅲ）→40%（Cycle Ⅳ）→36.8%（Cycle Ⅴ）→14.3%（Cycle Ⅵ）,and 23.8%（Cycle Ⅰ）→24.2%（Cycle Ⅲ）→10%（Cycle Ⅳ）→5.3%（Cycle Ⅴ）→71.4%（Cycle Ⅵ） from COB,DOB,and UYB,respectively.The results show that（1） COB behaved in considerable activation during the EarlyJurassic but weakened in the Middle Jurassic;（2） the vigorous tectonic uplift of DOB initiated in Middle Jurassic;and（3） UYB was in stabilization basically from the Early to Middle Jurassic.展开更多
BACKGROUND While Crohn’s disease has been studied extensively in high-income countries,its epidemiology and care in low and lower-middle income countries(LLMICs)is not well established due to a lack of disease regist...BACKGROUND While Crohn’s disease has been studied extensively in high-income countries,its epidemiology and care in low and lower-middle income countries(LLMICs)is not well established due to a lack of disease registries and diagnostic capacity.AIM To describe the published burden,diagnostic/treatment capacity,service utilization,challenges/barriers to individuals with Crohn’s in LLMICs and their providers.METHODS We conducted a scoping review utilizing a full search strategy was developed and conducted in PubMed,Embase and World Health Organization Global Index Medicus.Two independent reviewers screened the titles and abstracts of all of the publications found in this search,reviewed selected publications,and extracted relevant data,which underwent descriptive review and was analyzed in Excel.RESULTS The database search yielded 4486 publications,216 of which were determined to be relevant to the research questions.Of all 79 LLMICs,only 21(26.6%)have publications describing individuals with Crohn’s.Overall,the highest number of studies came from India,followed by Tunisia,and Egypt.The mean number of Crohn’s patients reported per study is 57.84 and the median is 22,with a wide range from one to 980.CONCLUSION This scoping review has shown that,although there is a severe lack of populationbased data about Crohn’s in LLMICs,there is a signal of Crohn’s in these settings around the world.展开更多
High-frequency metre-scale cycles are present within the Lower-Middle Ordovician carbonate successions in northern Tarim Basin, NW China. These metre-scale cycles were variably dolomitised from top to bottom. Three ty...High-frequency metre-scale cycles are present within the Lower-Middle Ordovician carbonate successions in northern Tarim Basin, NW China. These metre-scale cycles were variably dolomitised from top to bottom. Three types of replacive dolomites were recognised, including dololaminite(very finely to finely crystalline, planar-s to nonplanar-a dolomite;type-1), patterned dolomite(finely crystalline, planar-s dolomite; type-2), and mottled dolomite(finely to medium crystalline,nonplanar-a(s) dolomite; type-3). Petrographic evidence indicate these dolomites were primarily deposited in supratidal to restricted subtidal environments, and formed in near-surface to shallow burial realms. Geochemically, all types of dolomites have similar δ13C and 87Sr/86 Sr ratios comparable to calcite precipitated in equilibrium with the Early-Middle Ordovician seawater. These geochemical attributes indicate that these dolomites were genetically associated and likely formed from connate seawater-derived brines. Of these, type-1 dolomite has δ18O values(.4.97‰ to.4.04‰ VPDB) slightly higher than those of normal seawater dolomite of the Early-Middle Ordovician age. Considering the absence of associated evaporites within type-1 dolomite, its parental fluids were likely represented by slightly evaporated(i.e., mesosaline to penesaline) seawater with salinity below that of gypsum precipitation. More depleted δ18O values(.7.74‰ to.5.20‰ VPDB) of type-2 dolomite and its stratigraphic position below type-1 dolomite indicate the generation of this dolomite from mesosaline to penesaline brines at higher temperatures in near-surface to shallow burial domains. Type-3 dolomite yields the most depleted δ18O values(–9.30‰to –7.28‰ VPDB), pointing to that it was most likely formed from coeval seawater-derived brines at highest temperatures in a shallow burial setting. There is a downward decreasing trend in δ18O values from type-1 through type-2 to type-3 dolomites, and in abundance of dolomites, indicating that the dolomitising fluids probably migrated downward from above and persisted into shallow burial conditions.展开更多
The controversies on the division and correlation of the Devonian have never stopped since Lonsodale found and named the Devonian at Devonshire, Britain, especially on the determination and correlation of the Lower-Mi...The controversies on the division and correlation of the Devonian have never stopped since Lonsodale found and named the Devonian at Devonshire, Britain, especially on the determination and correlation of the Lower-Middle Devonian Boundary. The correlation between the different areas and sedimentary facies are still an international question although the international stratotype section has already been established. Recently,展开更多
As low and lower-middle social groups account for a great proportion of the total population in China and their status in society is special,it is of great social and practical significance to study their housing cond...As low and lower-middle social groups account for a great proportion of the total population in China and their status in society is special,it is of great social and practical significance to study their housing conditions and characteristics.Based on research at home and abroad,this paper defines the basic characteristics of low and lower-middle social groups in China,and elaborates the definition and connotation of housing marginalization,thereby proposing that these residents in the Chinese city are facing a problem of housing marginalization.According to data from the fifth and sixth population census and statistical yearbooks of Chengdu,it reveals changes in housing location,housing tenure structure,and housing quality of the study group between 2000 to 2010 by means of spatial and statistical analysis,which indicates that the low and lower-middle social groups are facing the three trends of"living in outskirts,""predicament in tenure selectivity of housing,"and"impoverishment of housing quality."In response to these trends,three planning suggestions are proposed:①to establish"housing policy areas"suitable for the group of residents to reside and work;②to innovate policy measures to support the low and lower-middle social groups to rent and purchase houses within these areas;③to guide the residents to integrate into the community life circle in these areas so as to avoid poverty concentration.展开更多
The paper deals with the background features, formation and distribution of the chemical el-ements K, Na, Ca, Mg, Si, Fe, Mn, Cr, Ni,V, Co, Ti, Mo, Cu, Pb, Zn, As, Hg, Cd, Be, Li, Sr, B,F, Cl, Br and I in the groundwa...The paper deals with the background features, formation and distribution of the chemical el-ements K, Na, Ca, Mg, Si, Fe, Mn, Cr, Ni,V, Co, Ti, Mo, Cu, Pb, Zn, As, Hg, Cd, Be, Li, Sr, B,F, Cl, Br and I in the groundwater in the region of the middle and lower reaches of the YangtzeRiver and their relations to the composition of the water-bearing media, properties of the overly-ing rocks and soils, redox environment, and groundwater flow condition, mineralization and pHof groundwater.展开更多
Multiple sets of thick coal beds characterized by simple structure and shallow burial depth were developed in the Early and Middle Jurassic strata of the Ordos Basin, northwestern China. The huge reserves of this high...Multiple sets of thick coal beds characterized by simple structure and shallow burial depth were developed in the Early and Middle Jurassic strata of the Ordos Basin, northwestern China. The huge reserves of this high quality coal have a high commercial value. We studied the coal＇s petrologic characteristics and its maceral distribution to determine the maceral＇s contribution to generation of oil and gas. The results show that the Jurassic coals in the Ordos Basin have special petrological features because of the Basin＇s unique depo- sitional environment which was mainly a series of high-stand swamps in the upper fluvial system. These petro- graphic features are a result of the development of typical inland lakes where some sand bodies were formed by migrating rivers. After burial, the peat continued to undergo oxidizing conditions, this process generated extensive higher inertinite contents in the coals and the vitrinite components were altered to semi-vitrinite. The macroscopic petrographic types of these Jurassic coals are mainly semi-dull coal, dull coal, semilustrous and lustrous coal. The proportions of semi-dull coal and dull coal are higher in the basin margins, especially in the area near the northern margin. The numbers of semilustrous and lustrous coals increase southwards and towards the central basin. This situation indicates that different coal-forming swamp environments have major controlling effects on the coal components. Another observation is that in the Ordos＇ coal sequences, especially in the lower part, some sandstone beds are thick, up to 20 m with a coarse grain size. The higher fusinite content in the macerals accompanies a higher semi-vitrinite content with more complete and regular plant cell structure. The fusinite structure is clear and well preserved. After burial, the lithology of the roof and floor rocks can continue to affect the evolution of coal petrology. The sand bodies in the roof and floor exhibit good physical conditions so that pore water can maintain a long-term state of oxidation, circulation and connection to the coal. So coal components remain in an oxidation environment for a long time. Conversely, in the basin center, lacustrine facies developed and peat was rapidly covered by mudstone after burial and subsequent coal beds rapidly entered a reducing environment. As a result, abundant gelatification occurred and the vitrinite content increased. E^inite often accumulated in a specific position in the coal bed. Although the average exinite content is not high on the whole, it does significantly contribute to the total hydrocarbon generation. The exinite content has been underestimated, especially the amorphous bituminous fluid and its importance is emphasized here. The reason is that the fluid flows easily into fusinite which has strong rigidity, or flows into some fissures, where it is commonly neglected.展开更多
The early Mesozoic granodiorites (ca.165 Ma) in the northeastern Hunan Province (NEH) have SiO2=65.4-69.65%, K2O/Na2O=0.95-1.38 and K2O+Na2O>6%, A/CNK=0.96-1.13 and belong to metaluminous high-K calc-alkaline serie...The early Mesozoic granodiorites (ca.165 Ma) in the northeastern Hunan Province (NEH) have SiO2=65.4-69.65%, K2O/Na2O=0.95-1.38 and K2O+Na2O>6%, A/CNK=0.96-1.13 and belong to metaluminous high-K calc-alkaline series. They are characterized by LREE and LILEs enrichment, and HFSE depletion with slightly negative Eu anomalies (Eu/Eu*=0.62-0.90). The initial 87Sr/86Sr ratios are in range from 0.711458 to 0.717461, and εNd values vary from -9.4 to -12.3, distinct from those of the contemporaneous granodiorites mantle-derived from the Southeastern Hunan Province (SEH) (87Sr/86Sr(i)=0.707962～0.710396, εNd(t)=-6.98～-2.30). By contrast, such signatures are roughly similar to those of the neighboring other Mesozoic granitic plutons (Eu/Eu*=0.30-0.70; 87Sr/86Sr >0.710; εNd = -12 to -16) in South China Block (SCB), which have been interpreted as the remelting products of Precambrian basement. The Proterozoic lower-middle crust is an important contributor to the petrogenesis of these early Mesozoic granodiorites in the NEH. An intracontinental extension setting is present in the northeastern Hunan Province at that time due to the demand of enough thermal transfer.展开更多
The Hefei Basin of eastern China developed in response to uplift of the Dabie Orogen,and zircon dating can be used to assess the exhumation history of the orogen.Zircons were collected from samples of the Lower Jurass...The Hefei Basin of eastern China developed in response to uplift of the Dabie Orogen,and zircon dating can be used to assess the exhumation history of the orogen.Zircons were collected from samples of the Lower Jurassic Fanghushan Formation and Middle Jurassic Sanjianpu Formation in the southern Hefei Basin,and mica-quartz schist and biotite granite gneiss from the Susong Complex of the Dabie Orogen.The zircon U-Pb dating was undertaken using laser ablation-inductively coupled plasma-mass spectrometry.The detrital zircons from conglomerates of the Fanghushan Formation and from clasts within the conglomerates have age-frequency distributions with the main clusters between 2.0 and 1.8 Ga,similar to age data of the Susong Complex.On the other hand,the zircons of the Fanghushan Formation do not show the age cluster at 1000–900 Ma that characterizes zircons in the underlying metasediments of the lower Paleozoic Foziling Group.A cluster of Triassic zircon ages also appears in the arkosic sandstones of the Fanghushan Formation.These data indicate that the provenance of the Fanghushan Formation was a mixture of high-pressure(HP)and ultrahigh-pressure(UHP)Triassic metamorphic rocks,Paleozoic magmatic rocks,and the Susong Complex,but not the lower Paleozoic Foziling Group even though it directly underlies the sediments of the Hefei Basin.Two samples from the Sanjianpu Formation show zircon age clusters at 797 and 791 Ma(middle Neoproterozoic)and 226 Ma(Triassic),and again,these are markedly different from the age clusters that characterize the Foziling Group.It seems,therefore,that despite the Foziling Group being at the surface in the underwater depositional area of the Hefei Basin,it was not exposed in the source area of the Hefei basinal sediments during the Jurassic,and there are two possible reasons for this.First,the exhumation of the Dabie Orogen was directed partly towards the north,in the process of which some of the Foziling Group was covered.Second,the Susong Complex rocks became involved in the development of an accretionary wedge,thus covering some of the Foziling Group during the process of subduction.展开更多
The banded or laminated exhalative hydrothermal chemical tourmalinite and mineralized tourmaline-rich sedimentary rocks were recognised for the first time in the stratabound and stratiform copper deposits in ghongtiao...The banded or laminated exhalative hydrothermal chemical tourmalinite and mineralized tourmaline-rich sedimentary rocks were recognised for the first time in the stratabound and stratiform copper deposits in ghongtiaoshan District in 1986, and further confirmed by the intensive investigations. The discovery can help better understand the geological environments and the origin of the stratabound and stratiform copper deposits.展开更多
基金supported by Guizhou Provincial Science and Technology Projects(No.ZK[2021]ordinary 199)the National Natural Science Foundation of China(Nos.42262019,92062221)the National Key R&D Program of China(No.2017YFC0603103)。
文摘The Yingshan Formation of the Lower-Middle Ordovician in the Tarim Basin(NW China)was mainly deposited in a shallow platform,which was intensely bioturbated with burrows filled with both dolomites and calcites.This study aims to figure out the controls on the dolomitization of burrow infills and the effects on petroleum reservoir quality based on petrographic examination,fluid inclusion microthermometry,and isotopic(C-O-Sr)geochemical analyses.The differentiation of burrow-associated carbonates(dolomites and calcites)was likely controlled by the interactions of sea-level oscillations of variable orders and depositional environments.The burrow-associated dolomites(BADs)were precipitated in a relatively restricted(i.e.,lagoon)depositional environment during the lowstand of long-term sea level.In contrast,the burrow-associated calcites(BACs)were formed in a water circulation-improved lagoonal environment during the transgression of long-term sea level.Isotopic geochemical data indicate that the BADs in the Yingshan Formation were formed from slightly saline(i.e.,mesosaline to penesaline)seawater,whereas the BACs were precipitated from nearly normal seawater.In addition to the anoxic condition,the presence of marine-sourced organic matter and sulfate-reducing bacteria,and a sufficient supply of dolomitizing fluids enriched in magnesium ions(Mg^(2+))and their Mg^(2+)concentration may have played a critical role in the formation of BADs.In the more permeable and disturbed burrow sediments as a result of burrowing,penetrating fluids with higher salinities and higher Mg^(2+)concentration relative to seawater favored dolomite precipitation.The fluids with seawater-like Mg^(2+)concentration,however,would lead to calcite precipitation.The progressive dolomitization of these burrowed sediments could have propagated the dolomitizing fronts and extended into ambient limestones,leading to the development of extensive dolomites.This dolomitization process can improve the petrophysical properties(porosity and permeability)and the potential as hydrocarbon reservoirs during the emplacement of hydrocarbons from underlying source rocks of the Cambrian to Lower Ordovician.
基金supported by the National Natural Science Foundation of China (Nos. 40672080, 40621002)the Program for Innovative Research Team in University of the Ministry of Education of China (No. IRT00546)
文摘The detrital modes of the sandstones from the south basin of Dabie（大别） orogenic belt during the Early-Middle Jurassic are complex due to multiple supplying.Detrital compositions of medium-coarse sandstones from the Lower-Middle Jurassic,Huangshi（黄石）,show three main provenances：recycled ororgen,volcanic arc（arc orogen）,and continental block on the bases of the Dickinson discriminating diagrams of modal composition and analysis of sandstone petrofacies.Combined with sparse published paleocurrent data,geotectonic setting of the study area,and the unpublished detrital zircon age data,the positions of the main provenances are inferred as follows：coastal orogenic belt（COB） in the East China provided detritus as the recycled orogen provenance;Dabie orogenic belt（DOB） to the north was the source of volcanic arc（arc orogen） materials;and the continental block clasts were likely from the uplift of the Yangtze basement（UYB）（Jiangnan（江南） uplift）.Six sedimentary cycles are recognized in the studied section,one in Wuchang（武昌） Formation,and five in Huajiahu（花家湖） Formation.During the deposition,the three main provenances play different roles.The quantitative petrofacies analysis revealed distinct changes of the effect from each source,that is,61.9%（Cycle Ⅰ）→54.5%（Cycle Ⅲ）→50%（Cycle Ⅳ）→57.9%（Cycle Ⅴ）→14.3%（Cycle Ⅵ）,14.3%（Cycle Ⅰ）→21.2%（ Cycle Ⅲ）→40%（Cycle Ⅳ）→36.8%（Cycle Ⅴ）→14.3%（Cycle Ⅵ）,and 23.8%（Cycle Ⅰ）→24.2%（Cycle Ⅲ）→10%（Cycle Ⅳ）→5.3%（Cycle Ⅴ）→71.4%（Cycle Ⅵ） from COB,DOB,and UYB,respectively.The results show that（1） COB behaved in considerable activation during the EarlyJurassic but weakened in the Middle Jurassic;（2） the vigorous tectonic uplift of DOB initiated in Middle Jurassic;and（3） UYB was in stabilization basically from the Early to Middle Jurassic.
文摘BACKGROUND While Crohn’s disease has been studied extensively in high-income countries,its epidemiology and care in low and lower-middle income countries(LLMICs)is not well established due to a lack of disease registries and diagnostic capacity.AIM To describe the published burden,diagnostic/treatment capacity,service utilization,challenges/barriers to individuals with Crohn’s in LLMICs and their providers.METHODS We conducted a scoping review utilizing a full search strategy was developed and conducted in PubMed,Embase and World Health Organization Global Index Medicus.Two independent reviewers screened the titles and abstracts of all of the publications found in this search,reviewed selected publications,and extracted relevant data,which underwent descriptive review and was analyzed in Excel.RESULTS The database search yielded 4486 publications,216 of which were determined to be relevant to the research questions.Of all 79 LLMICs,only 21(26.6%)have publications describing individuals with Crohn’s.Overall,the highest number of studies came from India,followed by Tunisia,and Egypt.The mean number of Crohn’s patients reported per study is 57.84 and the median is 22,with a wide range from one to 980.CONCLUSION This scoping review has shown that,although there is a severe lack of populationbased data about Crohn’s in LLMICs,there is a signal of Crohn’s in these settings around the world.
基金supported by Petrochemical Joint Foundation of China (Grant No. U1663209)National Natural Science Foundation of China (Grant No. 41502118)
文摘High-frequency metre-scale cycles are present within the Lower-Middle Ordovician carbonate successions in northern Tarim Basin, NW China. These metre-scale cycles were variably dolomitised from top to bottom. Three types of replacive dolomites were recognised, including dololaminite(very finely to finely crystalline, planar-s to nonplanar-a dolomite;type-1), patterned dolomite(finely crystalline, planar-s dolomite; type-2), and mottled dolomite(finely to medium crystalline,nonplanar-a(s) dolomite; type-3). Petrographic evidence indicate these dolomites were primarily deposited in supratidal to restricted subtidal environments, and formed in near-surface to shallow burial realms. Geochemically, all types of dolomites have similar δ13C and 87Sr/86 Sr ratios comparable to calcite precipitated in equilibrium with the Early-Middle Ordovician seawater. These geochemical attributes indicate that these dolomites were genetically associated and likely formed from connate seawater-derived brines. Of these, type-1 dolomite has δ18O values(.4.97‰ to.4.04‰ VPDB) slightly higher than those of normal seawater dolomite of the Early-Middle Ordovician age. Considering the absence of associated evaporites within type-1 dolomite, its parental fluids were likely represented by slightly evaporated(i.e., mesosaline to penesaline) seawater with salinity below that of gypsum precipitation. More depleted δ18O values(.7.74‰ to.5.20‰ VPDB) of type-2 dolomite and its stratigraphic position below type-1 dolomite indicate the generation of this dolomite from mesosaline to penesaline brines at higher temperatures in near-surface to shallow burial domains. Type-3 dolomite yields the most depleted δ18O values(–9.30‰to –7.28‰ VPDB), pointing to that it was most likely formed from coeval seawater-derived brines at highest temperatures in a shallow burial setting. There is a downward decreasing trend in δ18O values from type-1 through type-2 to type-3 dolomites, and in abundance of dolomites, indicating that the dolomitising fluids probably migrated downward from above and persisted into shallow burial conditions.
基金Project supported by the National Natural Science Foundation of China Doctoral Foundation of National Education Committee
文摘The controversies on the division and correlation of the Devonian have never stopped since Lonsodale found and named the Devonian at Devonshire, Britain, especially on the determination and correlation of the Lower-Middle Devonian Boundary. The correlation between the different areas and sedimentary facies are still an international question although the international stratotype section has already been established. Recently,
基金supported by the Youth Program of National Natural Science Foundation of China“Influencing Mechanism of Spatial Pattern of Resettlement Areas on the Reconstruction of Neighborhood Social Network of Relocated Residents:The Example of Caojiaxiang Project in Chengdu”(51808452)the Fundamental Research Funds for the Central Universities(2682019CX54)。
文摘As low and lower-middle social groups account for a great proportion of the total population in China and their status in society is special,it is of great social and practical significance to study their housing conditions and characteristics.Based on research at home and abroad,this paper defines the basic characteristics of low and lower-middle social groups in China,and elaborates the definition and connotation of housing marginalization,thereby proposing that these residents in the Chinese city are facing a problem of housing marginalization.According to data from the fifth and sixth population census and statistical yearbooks of Chengdu,it reveals changes in housing location,housing tenure structure,and housing quality of the study group between 2000 to 2010 by means of spatial and statistical analysis,which indicates that the low and lower-middle social groups are facing the three trends of"living in outskirts,""predicament in tenure selectivity of housing,"and"impoverishment of housing quality."In response to these trends,three planning suggestions are proposed:①to establish"housing policy areas"suitable for the group of residents to reside and work;②to innovate policy measures to support the low and lower-middle social groups to rent and purchase houses within these areas;③to guide the residents to integrate into the community life circle in these areas so as to avoid poverty concentration.
文摘The paper deals with the background features, formation and distribution of the chemical el-ements K, Na, Ca, Mg, Si, Fe, Mn, Cr, Ni,V, Co, Ti, Mo, Cu, Pb, Zn, As, Hg, Cd, Be, Li, Sr, B,F, Cl, Br and I in the groundwater in the region of the middle and lower reaches of the YangtzeRiver and their relations to the composition of the water-bearing media, properties of the overly-ing rocks and soils, redox environment, and groundwater flow condition, mineralization and pHof groundwater.
基金supported by Chinese Ministry of Science and Technology Project(No.2006CB202202)the National Natural Science Foundation of China(No.40972106 and No.40772095)
文摘Multiple sets of thick coal beds characterized by simple structure and shallow burial depth were developed in the Early and Middle Jurassic strata of the Ordos Basin, northwestern China. The huge reserves of this high quality coal have a high commercial value. We studied the coal＇s petrologic characteristics and its maceral distribution to determine the maceral＇s contribution to generation of oil and gas. The results show that the Jurassic coals in the Ordos Basin have special petrological features because of the Basin＇s unique depo- sitional environment which was mainly a series of high-stand swamps in the upper fluvial system. These petro- graphic features are a result of the development of typical inland lakes where some sand bodies were formed by migrating rivers. After burial, the peat continued to undergo oxidizing conditions, this process generated extensive higher inertinite contents in the coals and the vitrinite components were altered to semi-vitrinite. The macroscopic petrographic types of these Jurassic coals are mainly semi-dull coal, dull coal, semilustrous and lustrous coal. The proportions of semi-dull coal and dull coal are higher in the basin margins, especially in the area near the northern margin. The numbers of semilustrous and lustrous coals increase southwards and towards the central basin. This situation indicates that different coal-forming swamp environments have major controlling effects on the coal components. Another observation is that in the Ordos＇ coal sequences, especially in the lower part, some sandstone beds are thick, up to 20 m with a coarse grain size. The higher fusinite content in the macerals accompanies a higher semi-vitrinite content with more complete and regular plant cell structure. The fusinite structure is clear and well preserved. After burial, the lithology of the roof and floor rocks can continue to affect the evolution of coal petrology. The sand bodies in the roof and floor exhibit good physical conditions so that pore water can maintain a long-term state of oxidation, circulation and connection to the coal. So coal components remain in an oxidation environment for a long time. Conversely, in the basin center, lacustrine facies developed and peat was rapidly covered by mudstone after burial and subsequent coal beds rapidly entered a reducing environment. As a result, abundant gelatification occurred and the vitrinite content increased. E^inite often accumulated in a specific position in the coal bed. Although the average exinite content is not high on the whole, it does significantly contribute to the total hydrocarbon generation. The exinite content has been underestimated, especially the amorphous bituminous fluid and its importance is emphasized here. The reason is that the fluid flows easily into fusinite which has strong rigidity, or flows into some fissures, where it is commonly neglected.
基金This project was jointly supported by China National Natural Science Foundation(Grant No.40334039)CAS Knowledge Innovation Project(Grant No.KZCX1-102)CAS Key Laboratory ofIsotope Geochronology and Geochemistry(Grant No.GIGCX-03-01)
文摘The early Mesozoic granodiorites (ca.165 Ma) in the northeastern Hunan Province (NEH) have SiO2=65.4-69.65%, K2O/Na2O=0.95-1.38 and K2O+Na2O>6%, A/CNK=0.96-1.13 and belong to metaluminous high-K calc-alkaline series. They are characterized by LREE and LILEs enrichment, and HFSE depletion with slightly negative Eu anomalies (Eu/Eu*=0.62-0.90). The initial 87Sr/86Sr ratios are in range from 0.711458 to 0.717461, and εNd values vary from -9.4 to -12.3, distinct from those of the contemporaneous granodiorites mantle-derived from the Southeastern Hunan Province (SEH) (87Sr/86Sr(i)=0.707962～0.710396, εNd(t)=-6.98～-2.30). By contrast, such signatures are roughly similar to those of the neighboring other Mesozoic granitic plutons (Eu/Eu*=0.30-0.70; 87Sr/86Sr >0.710; εNd = -12 to -16) in South China Block (SCB), which have been interpreted as the remelting products of Precambrian basement. The Proterozoic lower-middle crust is an important contributor to the petrogenesis of these early Mesozoic granodiorites in the NEH. An intracontinental extension setting is present in the northeastern Hunan Province at that time due to the demand of enough thermal transfer.
基金supported by the National Natural Science Foundation of China(Grant Nos.41572186&41872216)。
文摘The Hefei Basin of eastern China developed in response to uplift of the Dabie Orogen,and zircon dating can be used to assess the exhumation history of the orogen.Zircons were collected from samples of the Lower Jurassic Fanghushan Formation and Middle Jurassic Sanjianpu Formation in the southern Hefei Basin,and mica-quartz schist and biotite granite gneiss from the Susong Complex of the Dabie Orogen.The zircon U-Pb dating was undertaken using laser ablation-inductively coupled plasma-mass spectrometry.The detrital zircons from conglomerates of the Fanghushan Formation and from clasts within the conglomerates have age-frequency distributions with the main clusters between 2.0 and 1.8 Ga,similar to age data of the Susong Complex.On the other hand,the zircons of the Fanghushan Formation do not show the age cluster at 1000–900 Ma that characterizes zircons in the underlying metasediments of the lower Paleozoic Foziling Group.A cluster of Triassic zircon ages also appears in the arkosic sandstones of the Fanghushan Formation.These data indicate that the provenance of the Fanghushan Formation was a mixture of high-pressure(HP)and ultrahigh-pressure(UHP)Triassic metamorphic rocks,Paleozoic magmatic rocks,and the Susong Complex,but not the lower Paleozoic Foziling Group even though it directly underlies the sediments of the Hefei Basin.Two samples from the Sanjianpu Formation show zircon age clusters at 797 and 791 Ma(middle Neoproterozoic)and 226 Ma(Triassic),and again,these are markedly different from the age clusters that characterize the Foziling Group.It seems,therefore,that despite the Foziling Group being at the surface in the underwater depositional area of the Hefei Basin,it was not exposed in the source area of the Hefei basinal sediments during the Jurassic,and there are two possible reasons for this.First,the exhumation of the Dabie Orogen was directed partly towards the north,in the process of which some of the Foziling Group was covered.Second,the Susong Complex rocks became involved in the development of an accretionary wedge,thus covering some of the Foziling Group during the process of subduction.
文摘The banded or laminated exhalative hydrothermal chemical tourmalinite and mineralized tourmaline-rich sedimentary rocks were recognised for the first time in the stratabound and stratiform copper deposits in ghongtiaoshan District in 1986, and further confirmed by the intensive investigations. The discovery can help better understand the geological environments and the origin of the stratabound and stratiform copper deposits.
