Saindak is one of the typical porphyry Cu deposits(PCDs)in the Chagai magmatic arc in Pakistan.Ore-forming porphyries at Saindak PCD are mainly composed of tonalite.Here,we use geochemistry of apatite enclosed in plag...Saindak is one of the typical porphyry Cu deposits(PCDs)in the Chagai magmatic arc in Pakistan.Ore-forming porphyries at Saindak PCD are mainly composed of tonalite.Here,we use geochemistry of apatite enclosed in plagioclase phenocrysts from the ore-forming tonalite to constrain the releasing and recharging processes of S and Cl in the underlying parental magma chamber during PCD mineralization.Although apatite inclusions have homogeneous intra-grain S and Cl compositions,there is significant inter-grain S and Cl variations in apatite inclusions located from core to rim in the hosting plagioclase.Such inter-grain S and Cl variation in apatites are coupled with the core-to-rim trends of An,FeO and Mg contents of the hosting plagioclase phenocryst.It indicates that the Saindak PCD likely formed by episodic injection of primitive magmas during the growth of an underlying magma chamber,rather than by one major injection or by addition of mafic melt derived from different source region.Each primitive melt injection introduced essential ore-forming materials such as S and Cl,which were rapidly and effectively released to the coexisting fluids,causing mineralization.Once primitive melt injection stops,signaling the end of growth of underlying magma chamber,mineralization will cease quickly although the hydrothermal system can still survive for a long time.However,the later released fluids are relatively depleted in ore-forming materials,and thus have lower capability to generate mineralization.Accordingly,predominant porphyry-type mineralizations occurred during the growth rather than waning stage of a magmatic system.展开更多
China’s urban expansion,food security,and energy transition are in a critical situation.One solution is to tap into the green production potential of the built urban environment and explore new ways to save land spac...China’s urban expansion,food security,and energy transition are in a critical situation.One solution is to tap into the green production potential of the built urban environment and explore new ways to save land space and alleviate ecological pressure through food and solar energy production.This paper differs from previous ecological compensation studies,which mostly focus on key ecological functional areas or fiscal compensation mechanisms,in that it innovatively establishes an ecological compensation mechanism within the urban space.In this paper,we propose the"green productive area"of cities as a way to measure the ecological carrying capacity improvement potential of cities from the perspective of urban ecology,and it is based on converting the green resource income of cities into the ecological footprint area they could save under the same conditions.First,a typological approach was used to establish a compensation strategy for green production.Second,a spatial inventory was taken of all elements of the built environment and an analysis of their green production potential was carried out.Finally,it was necessary to establish a unified accounting standard for the ecological land saving benefits of different green production options,which could be converted into green productive land area indicators.In the case of Xuefu Street in Nankai District,Tianjin,the available rooftops and idle land were used for green production,which supplemented the ecological carrying capacity provided by the natural land occupied by 12%of the buildings in the district.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2016YFC0600310)the National Natural Science Foundation of China(Grant Nos.41872083 and 41702091)+2 种基金the Program of the China Geological Survey(Grant No.DD20160024-07)the China Fundamental Research Funds for the Central Universities(Grant No.2652018133)the 111 Project of the Ministry of Science and Technology(Grant No.BP0719021)。
文摘Saindak is one of the typical porphyry Cu deposits(PCDs)in the Chagai magmatic arc in Pakistan.Ore-forming porphyries at Saindak PCD are mainly composed of tonalite.Here,we use geochemistry of apatite enclosed in plagioclase phenocrysts from the ore-forming tonalite to constrain the releasing and recharging processes of S and Cl in the underlying parental magma chamber during PCD mineralization.Although apatite inclusions have homogeneous intra-grain S and Cl compositions,there is significant inter-grain S and Cl variations in apatite inclusions located from core to rim in the hosting plagioclase.Such inter-grain S and Cl variation in apatites are coupled with the core-to-rim trends of An,FeO and Mg contents of the hosting plagioclase phenocryst.It indicates that the Saindak PCD likely formed by episodic injection of primitive magmas during the growth of an underlying magma chamber,rather than by one major injection or by addition of mafic melt derived from different source region.Each primitive melt injection introduced essential ore-forming materials such as S and Cl,which were rapidly and effectively released to the coexisting fluids,causing mineralization.Once primitive melt injection stops,signaling the end of growth of underlying magma chamber,mineralization will cease quickly although the hydrothermal system can still survive for a long time.However,the later released fluids are relatively depleted in ore-forming materials,and thus have lower capability to generate mineralization.Accordingly,predominant porphyry-type mineralizations occurred during the growth rather than waning stage of a magmatic system.
基金The National Natural Science Foundation of China(51978443,52078322)The Youth Program of National Natural Science Foundation ofChina(51708395)The Tianjin Graduate Research and Innovation Project in 2009(2019YJSB175).
文摘China’s urban expansion,food security,and energy transition are in a critical situation.One solution is to tap into the green production potential of the built urban environment and explore new ways to save land space and alleviate ecological pressure through food and solar energy production.This paper differs from previous ecological compensation studies,which mostly focus on key ecological functional areas or fiscal compensation mechanisms,in that it innovatively establishes an ecological compensation mechanism within the urban space.In this paper,we propose the"green productive area"of cities as a way to measure the ecological carrying capacity improvement potential of cities from the perspective of urban ecology,and it is based on converting the green resource income of cities into the ecological footprint area they could save under the same conditions.First,a typological approach was used to establish a compensation strategy for green production.Second,a spatial inventory was taken of all elements of the built environment and an analysis of their green production potential was carried out.Finally,it was necessary to establish a unified accounting standard for the ecological land saving benefits of different green production options,which could be converted into green productive land area indicators.In the case of Xuefu Street in Nankai District,Tianjin,the available rooftops and idle land were used for green production,which supplemented the ecological carrying capacity provided by the natural land occupied by 12%of the buildings in the district.
