Benxi area, Northeastern China, is the main distribution area of Archean BIF-hosted iron deposits in China. In this area, Nanfen iron deposit is well known as the largest open-pit iron deposit not only in China but al...Benxi area, Northeastern China, is the main distribution area of Archean BIF-hosted iron deposits in China. In this area, Nanfen iron deposit is well known as the largest open-pit iron deposit not only in China but also in Asia. So far, the tectonic nature during Archean BIF formation period in Benxi area has been long disputed and the tectonic setting of Nanfen BIF had not been found. In this study, the geochemical characters of chlorite amphibolites closely associated with BIF have been investigated for the tectonic environment of Nanfen BIF. Chlortie amphibolites show the geochemical affinity to the back-arc basin basalt (BABB), indicating that the tectonic environment of Nanfen BIF is the back-arc basin. In conjunction with geological evidence of other BIFs at Benxi area, it is identified that BIF in Benxi area might be formed in the subduction-related back-arc basin, which provides a favorable sedimentary environment of Algoma-type BIF.展开更多
In order to reveal the sedimentary environment of carbonate rocks in Nanfen Formation of Qingbaikou System in Tonghua,Jilin Province,the mineral composition and petrochemistry of carbonate rocks in Nanfen Formation we...In order to reveal the sedimentary environment of carbonate rocks in Nanfen Formation of Qingbaikou System in Tonghua,Jilin Province,the mineral composition and petrochemistry of carbonate rocks in Nanfen Formation were analyzed.The mineral compositions of five carbonate rock samples in Nanfen Formation mainly consist of calcite,with minor clay minerals and quartz,and the rock type is siliceous marlite.The Mn/Sr va-lues range from 1.52 to 4.08,with an average of 2.64,indicating that the carbonate rocks experienced weak diagenesis;the Sr/Ba values range from 1.26 to 2.51,with an average of 1.93,indicating marine environment;the ratio of Mg/Al ranges from 35.33 to 86.34,with an average of 62.95,indicating the seawater environment,which is consistent with the result from Sr/Ba;the MgO/CaO values range from 0.01 to 0.04,with an average of 0.02,indicating humid environment;the values of V/(V+Ni)range from 0.63 to 0.73,with an average of 0.70,indicating anoxic environment.In summary,geochemical analyses show that the Nanfen Formation carbonate rocks are marine deposits,in a warm,humid,anoxic environment with poor flow of seawater,and subsequently underwent weak diagenetic alteration.展开更多
县(市)地质灾害调查与区划空间数据库的建设是“全国县市地质灾害调查”专项项目的重要组成部分,本文阐述了以“县(市)地质灾害调查与区划信息系统”为基本建库工具,以M apG IS和FoxPro等软件为辅助工具,建立本溪市南芬区地质灾害调查...县(市)地质灾害调查与区划空间数据库的建设是“全国县市地质灾害调查”专项项目的重要组成部分,本文阐述了以“县(市)地质灾害调查与区划信息系统”为基本建库工具,以M apG IS和FoxPro等软件为辅助工具,建立本溪市南芬区地质灾害调查与区划空间数据库的过程.展开更多
文摘Benxi area, Northeastern China, is the main distribution area of Archean BIF-hosted iron deposits in China. In this area, Nanfen iron deposit is well known as the largest open-pit iron deposit not only in China but also in Asia. So far, the tectonic nature during Archean BIF formation period in Benxi area has been long disputed and the tectonic setting of Nanfen BIF had not been found. In this study, the geochemical characters of chlorite amphibolites closely associated with BIF have been investigated for the tectonic environment of Nanfen BIF. Chlortie amphibolites show the geochemical affinity to the back-arc basin basalt (BABB), indicating that the tectonic environment of Nanfen BIF is the back-arc basin. In conjunction with geological evidence of other BIFs at Benxi area, it is identified that BIF in Benxi area might be formed in the subduction-related back-arc basin, which provides a favorable sedimentary environment of Algoma-type BIF.
文摘In order to reveal the sedimentary environment of carbonate rocks in Nanfen Formation of Qingbaikou System in Tonghua,Jilin Province,the mineral composition and petrochemistry of carbonate rocks in Nanfen Formation were analyzed.The mineral compositions of five carbonate rock samples in Nanfen Formation mainly consist of calcite,with minor clay minerals and quartz,and the rock type is siliceous marlite.The Mn/Sr va-lues range from 1.52 to 4.08,with an average of 2.64,indicating that the carbonate rocks experienced weak diagenesis;the Sr/Ba values range from 1.26 to 2.51,with an average of 1.93,indicating marine environment;the ratio of Mg/Al ranges from 35.33 to 86.34,with an average of 62.95,indicating the seawater environment,which is consistent with the result from Sr/Ba;the MgO/CaO values range from 0.01 to 0.04,with an average of 0.02,indicating humid environment;the values of V/(V+Ni)range from 0.63 to 0.73,with an average of 0.70,indicating anoxic environment.In summary,geochemical analyses show that the Nanfen Formation carbonate rocks are marine deposits,in a warm,humid,anoxic environment with poor flow of seawater,and subsequently underwent weak diagenetic alteration.
