This study examines the rare earth elements and yttrium(REY)concentrations of twenty-five samples from the reef outcrop exposed along the Lianglitage Mountain in the Ordovician,Tarim Basin in China.The concentration a...This study examines the rare earth elements and yttrium(REY)concentrations of twenty-five samples from the reef outcrop exposed along the Lianglitage Mountain in the Ordovician,Tarim Basin in China.The concentration analysis provides constraints on the paleoenvironment during reef deposition.Based on the detailed sedimentology and petrographic work,we divide the reef facies into four sub-facies:the base facies,reef-core facies,reef-flank facies,and sealing facies.The geochemical data(such as major and trace elements,carbon and oxygen isotopes,and REYs)are further used to study the coeval seawater characteristics as well as potential diagenesis overprints.The result indicated that the diagenesis has little effect on the REY patterns of the reefal limestones.The REY concentrations of the reefal limestones are overall low(ranging from 3.69 to 19.60 ppm,arithmetic mean=10.22 ppm,SD=5.4).The PAAS-normalized REY patterns are consistently flat compared to the typical well-oxidized,shallow marine water patterns.However,the light REE(LREE)depletions,positive La anomalies,negative Ce anomalies and positive Y anomalies,suggest that these reefal limestones are likely an indicative of contemporaneous seawater REY signals.The seawater-like Y/Ho ratios(average at 37.51)further support that REY signals in these limestones are likely a reflection of seawater with little diagenetic modifications.The low Y/Ho ratios presented only in the reef-flank facies and sealing facies are likely a suggestion of detrital contamination.Hence,this study confirms that REY patterns of the limestones at the base facies and reef-core facies can record ancient seawater information,and reefs can be used as a potential geochemical proxy for paleoenvironment studies throughout the Earth’s history.展开更多
Objective Time-specific litho- and biofacies often holds important information about unique ancient ecosystems that no longer exist on Earth today. This report summarizes one of such time-specific facies--the 3-D net...Objective Time-specific litho- and biofacies often holds important information about unique ancient ecosystems that no longer exist on Earth today. This report summarizes one of such time-specific facies--the 3-D network structure of the Upper Ordovician Pagoda Formation in South China, as investigated by Zhan et al. （Palaeogeography, Palaeocli-matology, Palaeoecology, DOI： 10.1016/j.palaeo.2015.07.039）.展开更多
This research aimed to investigate the changing mechanism of hydro-geochemistry in Ordovician limestone karst(OL) water induced by mountainous coal mining activities. Thus, the hydrogeochemistry evolution of OL water ...This research aimed to investigate the changing mechanism of hydro-geochemistry in Ordovician limestone karst(OL) water induced by mountainous coal mining activities. Thus, the hydrogeochemistry evolution of OL water over 40 years within a typical northern mountainous coal mine named Fengfeng Mine was studied by using Piper diagram, Gibbs scheme, ions correlation and Principal component analysis(PCA) methods. Results showed that, except for HCO3^-, the ions of Ca^2+, Mg^2+, SO4^2-,Na^++K^+, Cl^- and total dissolution solids(TDS) values all increased by years as mining continues. Different hydro-geochemical characteristics in different periods can reflect different water-rock interactions.Accordingly, sulfates dissolution gradually took place of carbonates in water-rock interaction. Especially,OL water-rock interactions in different periods were all affected by rock weathering and evaporationconcentration together. At last, evaporationconcentration co-effect dominated the hydrogeochemistry evolution slowly, along with significant cations exchange over years.展开更多
Mosul and Haditha dams are two large earthfill dams in Iraq constructed on the Tigris and Euphrates rivers, respectively. The two dams were constructed almost at the same period in the mid-eighties of the last century...Mosul and Haditha dams are two large earthfill dams in Iraq constructed on the Tigris and Euphrates rivers, respectively. The two dams were constructed almost at the same period in the mid-eighties of the last century. Both dams suffer from karstification within their foundations. In the former, however, the problem is more severe than the latter. Mosul Dam was constructed on karstified gypsum and limestone beds;different grouting techniques were used, but the works in grouting are still going on to keep the dam as safe as possible as the sealing of the foundation is hampered by the type of geology. Haditha Dam was constructed on karstified limestone and gypsum rocks also. To avoid the effect of the karstification on the safety of this dam, an exceptionally long grout curtain was constructed as foundation treatment work. The length of the grout curtain extended under the earthfill dam and the concrete structures in the river channel and extended beyond the abutments forming left and right sides extensions to cut off water percolation around the dam which could cause the formation of sinkholes. The depths of all parts of the curtain varied following the karstification zones and intensities. The details of both dams are discussed using updated data and relying on the experience of the authors. The current status of both dams is also discussed with some recommendations to keep both dams as safe as possible.展开更多
奥灰岩溶裂隙含水层是影响华北型煤矿深部开采的重要水害,在水-岩相互作用下奥灰含水层易导致煤层底板突水。为进一步认识奥灰岩溶突水问题,文章以新集矿区深部1煤层开采为例,利用矿区近些年最新积累的奥灰钻孔资料,选取断层强度指数、...奥灰岩溶裂隙含水层是影响华北型煤矿深部开采的重要水害,在水-岩相互作用下奥灰含水层易导致煤层底板突水。为进一步认识奥灰岩溶突水问题,文章以新集矿区深部1煤层开采为例,利用矿区近些年最新积累的奥灰钻孔资料,选取断层强度指数、断层交叉点与尖灭点、含水层水压、富水性、隔水层等效厚度、脆塑比7个因素作为奥灰岩溶突水的主控因素,并结合层次分析法(analytic hierarchy process,AHP)确定各主控因素影响权重。运用地理信息系统(geographic information system,GIS)空间分析功能建立各主控因素专题图,通过对专题栅格图归一化处理,将各主控因素按照权重进行空间复合叠加,最终获得1煤层底板奥灰岩溶突水危险性评价分区结果。将评价结果与突水系数法计算结果对比分析可知,基于GIS的煤层底板突水危险性评价方法更符合矿区实际地质情况,可以为矿区深部煤层开采与水害防治工作提供参考依据。展开更多
基金supported by the National Natural Science Foundation of China(grant number 51574208)the National 973 Program of China(grant number 2012CB214802)+1 种基金the China Geological Survery Project(grant number DD20190217)the China Scholar Council(grant number 201606400023)for providing the financial support
文摘This study examines the rare earth elements and yttrium(REY)concentrations of twenty-five samples from the reef outcrop exposed along the Lianglitage Mountain in the Ordovician,Tarim Basin in China.The concentration analysis provides constraints on the paleoenvironment during reef deposition.Based on the detailed sedimentology and petrographic work,we divide the reef facies into four sub-facies:the base facies,reef-core facies,reef-flank facies,and sealing facies.The geochemical data(such as major and trace elements,carbon and oxygen isotopes,and REYs)are further used to study the coeval seawater characteristics as well as potential diagenesis overprints.The result indicated that the diagenesis has little effect on the REY patterns of the reefal limestones.The REY concentrations of the reefal limestones are overall low(ranging from 3.69 to 19.60 ppm,arithmetic mean=10.22 ppm,SD=5.4).The PAAS-normalized REY patterns are consistently flat compared to the typical well-oxidized,shallow marine water patterns.However,the light REE(LREE)depletions,positive La anomalies,negative Ce anomalies and positive Y anomalies,suggest that these reefal limestones are likely an indicative of contemporaneous seawater REY signals.The seawater-like Y/Ho ratios(average at 37.51)further support that REY signals in these limestones are likely a reflection of seawater with little diagenetic modifications.The low Y/Ho ratios presented only in the reef-flank facies and sealing facies are likely a suggestion of detrital contamination.Hence,this study confirms that REY patterns of the limestones at the base facies and reef-core facies can record ancient seawater information,and reefs can be used as a potential geochemical proxy for paleoenvironment studies throughout the Earth’s history.
基金supported by the National Natural Science Foundation of China(grant No.41521061, 41290260)the State Key Laboratory of Paleobiology and Stratigraphy(LPS)
文摘Objective Time-specific litho- and biofacies often holds important information about unique ancient ecosystems that no longer exist on Earth today. This report summarizes one of such time-specific facies--the 3-D network structure of the Upper Ordovician Pagoda Formation in South China, as investigated by Zhan et al. （Palaeogeography, Palaeocli-matology, Palaeoecology, DOI： 10.1016/j.palaeo.2015.07.039）.
基金Key Laboratory of Water Resource Protection and Utilization in Coal Mining(Grant No.SHJT-17-42.17)Fundamental Research Funds for the Central Universities of China(Grant Nos.3142018009,3142017100)Key Laboratory of Mine Geological Hazards Mechanism and Control Project(KF2017-13).Figure 7 PCA plot of hydro-chemistry of Ordovician limestone karst(OL)water samples from different years.
文摘This research aimed to investigate the changing mechanism of hydro-geochemistry in Ordovician limestone karst(OL) water induced by mountainous coal mining activities. Thus, the hydrogeochemistry evolution of OL water over 40 years within a typical northern mountainous coal mine named Fengfeng Mine was studied by using Piper diagram, Gibbs scheme, ions correlation and Principal component analysis(PCA) methods. Results showed that, except for HCO3^-, the ions of Ca^2+, Mg^2+, SO4^2-,Na^++K^+, Cl^- and total dissolution solids(TDS) values all increased by years as mining continues. Different hydro-geochemical characteristics in different periods can reflect different water-rock interactions.Accordingly, sulfates dissolution gradually took place of carbonates in water-rock interaction. Especially,OL water-rock interactions in different periods were all affected by rock weathering and evaporationconcentration together. At last, evaporationconcentration co-effect dominated the hydrogeochemistry evolution slowly, along with significant cations exchange over years.
文摘Mosul and Haditha dams are two large earthfill dams in Iraq constructed on the Tigris and Euphrates rivers, respectively. The two dams were constructed almost at the same period in the mid-eighties of the last century. Both dams suffer from karstification within their foundations. In the former, however, the problem is more severe than the latter. Mosul Dam was constructed on karstified gypsum and limestone beds;different grouting techniques were used, but the works in grouting are still going on to keep the dam as safe as possible as the sealing of the foundation is hampered by the type of geology. Haditha Dam was constructed on karstified limestone and gypsum rocks also. To avoid the effect of the karstification on the safety of this dam, an exceptionally long grout curtain was constructed as foundation treatment work. The length of the grout curtain extended under the earthfill dam and the concrete structures in the river channel and extended beyond the abutments forming left and right sides extensions to cut off water percolation around the dam which could cause the formation of sinkholes. The depths of all parts of the curtain varied following the karstification zones and intensities. The details of both dams are discussed using updated data and relying on the experience of the authors. The current status of both dams is also discussed with some recommendations to keep both dams as safe as possible.
文摘奥灰岩溶裂隙含水层是影响华北型煤矿深部开采的重要水害,在水-岩相互作用下奥灰含水层易导致煤层底板突水。为进一步认识奥灰岩溶突水问题,文章以新集矿区深部1煤层开采为例,利用矿区近些年最新积累的奥灰钻孔资料,选取断层强度指数、断层交叉点与尖灭点、含水层水压、富水性、隔水层等效厚度、脆塑比7个因素作为奥灰岩溶突水的主控因素,并结合层次分析法(analytic hierarchy process,AHP)确定各主控因素影响权重。运用地理信息系统(geographic information system,GIS)空间分析功能建立各主控因素专题图,通过对专题栅格图归一化处理,将各主控因素按照权重进行空间复合叠加,最终获得1煤层底板奥灰岩溶突水危险性评价分区结果。将评价结果与突水系数法计算结果对比分析可知,基于GIS的煤层底板突水危险性评价方法更符合矿区实际地质情况,可以为矿区深部煤层开采与水害防治工作提供参考依据。
