Based upon a comprehensive study of 123 copper deposits in China. this paper reaches the following conclusions: 1. The crust in China was solidified pretty late; with the accretion of the plate, the copper mineralizat...Based upon a comprehensive study of 123 copper deposits in China. this paper reaches the following conclusions: 1. The crust in China was solidified pretty late; with the accretion of the plate, the copper mineralization moved towards its margin in space and became successively younger in age. 2. The major copper ore types ever found in the world have mostly been discovered in China, in which the porphyry type seems to be the most important and the massive sulfide type in the transitional bed between marine clastic and carbonate rocks is clearly defined. 3. Carbonate strata are widespread in China and their deposition lasted for a long geological period, so the proportion of copper deposits occurring in them is large as compared with other parts of the world. 4. Seven metallogenic epochs can be recognized, in which the Mesozoic one plays the leading role and the middle(late) Palaeozoic and Cenozoic ones are next in importance. Mineralization was comparatively simple in the early geological period. and became diversified later on. In the early epochs copper deposits related to basaltic magmatism and metamorphosed marine sediments predominated, whereas in the later epochs those related to granitic magmatism and continental sedimentation were dominant. 5. There exist in China thirteen metallogenic provinces, of which the Lower Yangtze downwarping belt, Sanjiang fold system, Jiangnan axis and Xikang-Yunnan axis are of greater significance. 6. The crustal mobility in China was rather pronounced, the polycyclic evolution of the crust has resulted in such obvious phenomena as the inheritance of mineralization, the coexistence of various types and the superposition of different genetic types.展开更多
In recent years,several large and medium-sized ore deposits have been discovered in the shallow cover of Xuancheng,Anhui Province,indicating that this area has a productive metallogenic geological background and may b...In recent years,several large and medium-sized ore deposits have been discovered in the shallow cover of Xuancheng,Anhui Province,indicating that this area has a productive metallogenic geological background and may be a potential prospecting region.Based on systematic investigation,the geological and mineralization characteristics of porphyry Cu-Au deposits and skarn Cu-Mo-W deposits in this region have been summarized.Zircon U-Pb dating(LA-ICPMS)of the Chating quartz-diorite porphyry and the Kunshan biotite pyroxene diorite yield concordia ages of 145.5±2.1 Ma and 131.8±2.1 Ma,respectively.Meanwhile,the Re-Os dating analyses for molybdenite from the Shizishan and Magushan skarn Cu-Mo deposits yielded 133.81±0.86 Ma and 143.8±1.4 Ma ages,respectively.When viewed in conjunction with previous studies,it is suggested that twostage(the early stage of 145-135 Ma and the late stage of 134-125 Ma)magmatism may have occurred during the Mesozoic in Xuancheng region.Early stage intrusive rocks are distributed along both sides of the Jiangnan deep fault(JDF).The intrusive rocks to the north of the JDF are mainly quartzdiorite porphyry and granodiorite(porphyry)rocks,related to porphyry Cu-Au deposits and skarn-type Cu-Mo-W deposits.These deposits belong to the first stage of the porphyry-skarn copper gold metallogenic belt of the Middle-Lower Yangtze Metallogenic Belt(MLYB),associated with the high potassium calc-alkaline intermediate-acid intrusions.The magmatic and ore-forming materials are mainly derived from the enriched lithospheric mantle.South of the JDF,the Magushan granodiorite is a representative intrusive rock of the first stage I-type granite,which hosts the Magushan Cu-Mo skarn deposit,similar to the W-Mo-Cu skarn deposits in the Eastern Segment of the Jiangnan Uplift Metallogenic Belt(ESJUB).The magmatic and metallogenic materials mainly came from the Neoproterozoic basement,with the possible participation of a small amount of mantle components.The late stage magmatism was dominated by volcanic rocks with a small amount of intrusive rocks,which were consistent with the limited volcanic-intrusive activities in the second stage of the MLYB.The H-O stable isotopes of ore deposits in the region indicate that the ore-forming hydrothermal fluids of the porphyry and skarn deposits were mostly of magmatic water for the ore-forming stage,the percentage of meteoric water obviously increasing during the late ore-forming stage.The ore-forming materials of the deposits are mainly from the deep magma with a few sedimentary wall rocks,according to the stable carbon isotopes of the carbonates in the ore deposits.Additionally,according to previous research,the molybdenite from the MLYB has a higher Re content than that of the ESJUB.The higher content of Re in the molybdenite from the Shizishan deposit is identical to that of MLYB rather than ESJUB,whereas Re characteristics in molybdenite of Magushan deposit are similar to that of ESJUB.The differences in Re characteristics indicate the different deep processes and ore-forming material sources(mainly mantle composition for the former and crustal materials for the latter)of these ore deposits on opposite sides of the JDF.展开更多
The relics of ancient rice have been regarded as the most important objective evidence of the origina- tion and spread of rice cultivation.Based on the records of 280 rice relics sites and the rice cropping regionaliz...The relics of ancient rice have been regarded as the most important objective evidence of the origina- tion and spread of rice cultivation.Based on the records of 280 rice relics sites and the rice cropping regionalization as well as the distribution map of paddy soils,the current study compiled the temporal and spatial distribution map of ancient rice distribution in China.The map shows that the distribution of ancient rice is spatially extensive and meantime comparatively concentrated,temporarily covering a long and relatively continuous time-span.The rice relics in the Central China double and single rice cropping regions are among the earliest and the most abundant ones,possessing continuity in time sequence.Combined with the discovery of ancient rice and paddy filed relics,soil micromorphology, pollen combination and element geochemistry,it is suggested that Central China was the origin center of rice cultivation in China.Rice had been spread to the rest part of China in three major waves,also to the East Asian part like Korea and Japan.The temporal and spatial distribution of ancient rice reflects the past environmental change,which is also meaningful to the current rice regionalization and plan- ning as well as food security in China.展开更多
Degradation in visibility occurs extensively across China,creating the urgent need to better understand visibility patterns and characteristics in China.Using daily observation data from the U.S.National Climatic Data...Degradation in visibility occurs extensively across China,creating the urgent need to better understand visibility patterns and characteristics in China.Using daily observation data from the U.S.National Climatic Data Center(NCDC)during 1976–2010,the spatial distribution and temporal trends of visibility in China,as well as seasonal and regional characteristics,were determined.The distribution of visibility was characterized by a longitudinal gradient between west and east China.The northwest of China generally experienced consistent high visibility of[20 km,while central and eastern China experienced visibility degradation and increase in haziness.The 133stations with significant downward trends in visibility were clustered around central-east China and the average reduction rate was-1.65 km/decade(from 18.5 km).The96 stations with increasing trends of visibility were mostly on the Qinghai–Tibet Plateau and Xinjiang and were closely related to a reduction in local sand storms.The average visibility in 12 key regions in China varied between9.9–17.8 km(except for 23.9 km in Urumqi),which was lower than the national average of 18.7 km.The Taiyuan–Hohhot,Guanzhong,Yangtze River Delta,Pearl River Delta and Fuzhou–Xiamen areas all encountered significant decreases in visibility,while minor increases were observed in Beijing–Tianjin–Hebei and the Cheng-Yu region.At most stations,the worst visibility was measured in winter,but the season with best visibility varied between regions.A comparison of visibility trends with the emission trends of various pollutants revealed that SO2emissions dominated the visibility degradation in eastern Chinawith NOxand volatile organic compounds playing ascending roles during the 2000s.展开更多
相较于暴雨这种日尺度强降水,短时强降水(≥20 mm h^(−1))是造成山洪滑坡与城市内涝等灾害更为直接的因素。本文利用地面气象观测站和ERA5再分析数据,重点研究南海季风爆发前后珠江三角洲地区(简称珠三角)短时强降水的时空演变特征,并...相较于暴雨这种日尺度强降水,短时强降水(≥20 mm h^(−1))是造成山洪滑坡与城市内涝等灾害更为直接的因素。本文利用地面气象观测站和ERA5再分析数据,重点研究南海季风爆发前后珠江三角洲地区(简称珠三角)短时强降水的时空演变特征,并探索了短时强降水在季风爆发前后特征差异的可能成因。研究表明:(1)相较于季风爆发前,珠三角地区季风爆发后的降水明显增多,其中短时强降水贡献的比例显著增加。对短时强降水本身而言,区域平均强度以及极端性在季风爆发前后差异总体较小,但短时强降水频率在季风爆发后增加70%。(2)短时强降水高发区主要集中在珠三角东北部和珠江口西侧沿海,季风爆发后上述两个地区的频次增多最明显。短时强降水频率由季风爆发前的单峰型(下午)转为季风爆发后的双峰型(早晨与下午)。(3)短时强降水具有明显的区域性变化特征,短时强降水在季风爆发后的平均雨强和极端性在珠江口西侧沿海较内陆地区明显增强,其频次峰值时间在沿海地区从季风爆发前的午后转为季风爆发后的早晨,内陆地区在季风爆发前后均集中在下午。(4)季风爆发后,短时强降水期间的低层环境水汽超过同期气候态水平的16%。充沛的水汽在夜间在季风加速作用下被输送至沿海,并与陆风作用增强了辐合,这解释了沿海短时强降水的在季风爆发前后频次峰值时间转换现象。(5)相较于季风爆发前,季风爆发后珠三角短时强降水频率与低层水汽通量的相关性明显升高。珠三角沿海地区夜间—早晨短时强降水的增多与中低层风场结构改变造成的动力强迫有关。内陆地区季风爆发前后短时强降水与环境热力和不稳定条件关系更大。这些结果有助于我们更好地了解珠三角地区在季风爆发前后短时强降水的时空分布特征和理解其产生机制。展开更多
文摘Based upon a comprehensive study of 123 copper deposits in China. this paper reaches the following conclusions: 1. The crust in China was solidified pretty late; with the accretion of the plate, the copper mineralization moved towards its margin in space and became successively younger in age. 2. The major copper ore types ever found in the world have mostly been discovered in China, in which the porphyry type seems to be the most important and the massive sulfide type in the transitional bed between marine clastic and carbonate rocks is clearly defined. 3. Carbonate strata are widespread in China and their deposition lasted for a long geological period, so the proportion of copper deposits occurring in them is large as compared with other parts of the world. 4. Seven metallogenic epochs can be recognized, in which the Mesozoic one plays the leading role and the middle(late) Palaeozoic and Cenozoic ones are next in importance. Mineralization was comparatively simple in the early geological period. and became diversified later on. In the early epochs copper deposits related to basaltic magmatism and metamorphosed marine sediments predominated, whereas in the later epochs those related to granitic magmatism and continental sedimentation were dominant. 5. There exist in China thirteen metallogenic provinces, of which the Lower Yangtze downwarping belt, Sanjiang fold system, Jiangnan axis and Xikang-Yunnan axis are of greater significance. 6. The crustal mobility in China was rather pronounced, the polycyclic evolution of the crust has resulted in such obvious phenomena as the inheritance of mineralization, the coexistence of various types and the superposition of different genetic types.
基金supported by the National Key Research and Development Program of China(2016YFC0600209)。
文摘In recent years,several large and medium-sized ore deposits have been discovered in the shallow cover of Xuancheng,Anhui Province,indicating that this area has a productive metallogenic geological background and may be a potential prospecting region.Based on systematic investigation,the geological and mineralization characteristics of porphyry Cu-Au deposits and skarn Cu-Mo-W deposits in this region have been summarized.Zircon U-Pb dating(LA-ICPMS)of the Chating quartz-diorite porphyry and the Kunshan biotite pyroxene diorite yield concordia ages of 145.5±2.1 Ma and 131.8±2.1 Ma,respectively.Meanwhile,the Re-Os dating analyses for molybdenite from the Shizishan and Magushan skarn Cu-Mo deposits yielded 133.81±0.86 Ma and 143.8±1.4 Ma ages,respectively.When viewed in conjunction with previous studies,it is suggested that twostage(the early stage of 145-135 Ma and the late stage of 134-125 Ma)magmatism may have occurred during the Mesozoic in Xuancheng region.Early stage intrusive rocks are distributed along both sides of the Jiangnan deep fault(JDF).The intrusive rocks to the north of the JDF are mainly quartzdiorite porphyry and granodiorite(porphyry)rocks,related to porphyry Cu-Au deposits and skarn-type Cu-Mo-W deposits.These deposits belong to the first stage of the porphyry-skarn copper gold metallogenic belt of the Middle-Lower Yangtze Metallogenic Belt(MLYB),associated with the high potassium calc-alkaline intermediate-acid intrusions.The magmatic and ore-forming materials are mainly derived from the enriched lithospheric mantle.South of the JDF,the Magushan granodiorite is a representative intrusive rock of the first stage I-type granite,which hosts the Magushan Cu-Mo skarn deposit,similar to the W-Mo-Cu skarn deposits in the Eastern Segment of the Jiangnan Uplift Metallogenic Belt(ESJUB).The magmatic and metallogenic materials mainly came from the Neoproterozoic basement,with the possible participation of a small amount of mantle components.The late stage magmatism was dominated by volcanic rocks with a small amount of intrusive rocks,which were consistent with the limited volcanic-intrusive activities in the second stage of the MLYB.The H-O stable isotopes of ore deposits in the region indicate that the ore-forming hydrothermal fluids of the porphyry and skarn deposits were mostly of magmatic water for the ore-forming stage,the percentage of meteoric water obviously increasing during the late ore-forming stage.The ore-forming materials of the deposits are mainly from the deep magma with a few sedimentary wall rocks,according to the stable carbon isotopes of the carbonates in the ore deposits.Additionally,according to previous research,the molybdenite from the MLYB has a higher Re content than that of the ESJUB.The higher content of Re in the molybdenite from the Shizishan deposit is identical to that of MLYB rather than ESJUB,whereas Re characteristics in molybdenite of Magushan deposit are similar to that of ESJUB.The differences in Re characteristics indicate the different deep processes and ore-forming material sources(mainly mantle composition for the former and crustal materials for the latter)of these ore deposits on opposite sides of the JDF.
基金Supported by the National Natural Science Foundation of China(Grant Nos.40625001 and 40235054)
文摘The relics of ancient rice have been regarded as the most important objective evidence of the origina- tion and spread of rice cultivation.Based on the records of 280 rice relics sites and the rice cropping regionalization as well as the distribution map of paddy soils,the current study compiled the temporal and spatial distribution map of ancient rice distribution in China.The map shows that the distribution of ancient rice is spatially extensive and meantime comparatively concentrated,temporarily covering a long and relatively continuous time-span.The rice relics in the Central China double and single rice cropping regions are among the earliest and the most abundant ones,possessing continuity in time sequence.Combined with the discovery of ancient rice and paddy filed relics,soil micromorphology, pollen combination and element geochemistry,it is suggested that Central China was the origin center of rice cultivation in China.Rice had been spread to the rest part of China in three major waves,also to the East Asian part like Korea and Japan.The temporal and spatial distribution of ancient rice reflects the past environmental change,which is also meaningful to the current rice regionalization and plan- ning as well as food security in China.
基金the financial support from the Ministry of Environmental Protection in China (201009001)the Energy Foundation (US) for the scholarship to this study
文摘Degradation in visibility occurs extensively across China,creating the urgent need to better understand visibility patterns and characteristics in China.Using daily observation data from the U.S.National Climatic Data Center(NCDC)during 1976–2010,the spatial distribution and temporal trends of visibility in China,as well as seasonal and regional characteristics,were determined.The distribution of visibility was characterized by a longitudinal gradient between west and east China.The northwest of China generally experienced consistent high visibility of[20 km,while central and eastern China experienced visibility degradation and increase in haziness.The 133stations with significant downward trends in visibility were clustered around central-east China and the average reduction rate was-1.65 km/decade(from 18.5 km).The96 stations with increasing trends of visibility were mostly on the Qinghai–Tibet Plateau and Xinjiang and were closely related to a reduction in local sand storms.The average visibility in 12 key regions in China varied between9.9–17.8 km(except for 23.9 km in Urumqi),which was lower than the national average of 18.7 km.The Taiyuan–Hohhot,Guanzhong,Yangtze River Delta,Pearl River Delta and Fuzhou–Xiamen areas all encountered significant decreases in visibility,while minor increases were observed in Beijing–Tianjin–Hebei and the Cheng-Yu region.At most stations,the worst visibility was measured in winter,but the season with best visibility varied between regions.A comparison of visibility trends with the emission trends of various pollutants revealed that SO2emissions dominated the visibility degradation in eastern Chinawith NOxand volatile organic compounds playing ascending roles during the 2000s.
文摘相较于暴雨这种日尺度强降水,短时强降水(≥20 mm h^(−1))是造成山洪滑坡与城市内涝等灾害更为直接的因素。本文利用地面气象观测站和ERA5再分析数据,重点研究南海季风爆发前后珠江三角洲地区(简称珠三角)短时强降水的时空演变特征,并探索了短时强降水在季风爆发前后特征差异的可能成因。研究表明:(1)相较于季风爆发前,珠三角地区季风爆发后的降水明显增多,其中短时强降水贡献的比例显著增加。对短时强降水本身而言,区域平均强度以及极端性在季风爆发前后差异总体较小,但短时强降水频率在季风爆发后增加70%。(2)短时强降水高发区主要集中在珠三角东北部和珠江口西侧沿海,季风爆发后上述两个地区的频次增多最明显。短时强降水频率由季风爆发前的单峰型(下午)转为季风爆发后的双峰型(早晨与下午)。(3)短时强降水具有明显的区域性变化特征,短时强降水在季风爆发后的平均雨强和极端性在珠江口西侧沿海较内陆地区明显增强,其频次峰值时间在沿海地区从季风爆发前的午后转为季风爆发后的早晨,内陆地区在季风爆发前后均集中在下午。(4)季风爆发后,短时强降水期间的低层环境水汽超过同期气候态水平的16%。充沛的水汽在夜间在季风加速作用下被输送至沿海,并与陆风作用增强了辐合,这解释了沿海短时强降水的在季风爆发前后频次峰值时间转换现象。(5)相较于季风爆发前,季风爆发后珠三角短时强降水频率与低层水汽通量的相关性明显升高。珠三角沿海地区夜间—早晨短时强降水的增多与中低层风场结构改变造成的动力强迫有关。内陆地区季风爆发前后短时强降水与环境热力和不稳定条件关系更大。这些结果有助于我们更好地了解珠三角地区在季风爆发前后短时强降水的时空分布特征和理解其产生机制。
