1.Objective Because of the characteristics of multistage mineralization,long duration,relatively new age,and complicated occurrence of ore minerals,dating of sandstone-type uranium deposits has been a challenging prob...1.Objective Because of the characteristics of multistage mineralization,long duration,relatively new age,and complicated occurrence of ore minerals,dating of sandstone-type uranium deposits has been a challenging problem.For a long time,the whole-rock U-Pb isochronal method has been used in the dating of sandstone-type uranium deposits,but its accuracy has been questioned by experts.展开更多
The newly discovered medium-scale Huangling uranium deposit is located in the Shuanlong area of the southeast Ordos Basin.This paper presents the systematic geochemical and zircon U-Pb studies on the Zhiluo Formation ...The newly discovered medium-scale Huangling uranium deposit is located in the Shuanlong area of the southeast Ordos Basin.This paper presents the systematic geochemical and zircon U-Pb studies on the Zhiluo Formation sandstones in the Huanling area.The data obtained play an important role in deducing the provenance and tectonic setting of the source rocks.The results show that the lower part of the Zhiluo Formation is mainly composed of felsic sedimentary rocks.The source rocks originated from a continental island arc environment in terms of tectonic setting.U-Pb ages of detrital zircons obtained can be roughly divided into three groups:170‒500 Ma,1600‒2050 Ma,and 2100‒2650 Ma.Based on the characteristics of trace elements and rare earth elements(REE)and the zircon U-Pb dating results,it is considered that the Cryptozoic Edo provenance of the Zhiluo Formation mainly includes magmatic rocks(such as granodioritic intrusions)and metamorphic rocks(such as gneiss and granulite)in the orogenic belts on the northern margin of the North China Plate and in the Alxa Block.Based on sedimentological and petrological results,it can be concluded that the provenance of clastic sediments in the Zhiluo Formation was in north-south direction.The preconcentration of uranium is relatively low in the Lower Zhiluo Formation in the Huangling area.Meanwhile,the paleocurrent system in the sedimentary period is inconsistent with the ore-bearing flow field in the mineralization period,which restricts the formation of large-scale and super-large-scale uranium deposits and ore zones in the southeast Ordos Basin.The understanding of provenance directions will provide crucial references for the Jurassic prototype recovery and paleo-geomorphology of the Ordos Basin and the prediction of potential uranium reservoirs of the basin.展开更多
基金This study is supported by the National Key Research and Development Project(2018YFC0604200)the International Geoscience Programme(IGCP 675)the project of Geological Survey China(DD20190119).
文摘1.Objective Because of the characteristics of multistage mineralization,long duration,relatively new age,and complicated occurrence of ore minerals,dating of sandstone-type uranium deposits has been a challenging problem.For a long time,the whole-rock U-Pb isochronal method has been used in the dating of sandstone-type uranium deposits,but its accuracy has been questioned by experts.
基金This study was funded by the project initiated by the China Geological Survey“Investigation of sandstone-type uranium deposits in the Ordos and Qaidam Basins”(DD20190119)the National Key Research and Development Project(2018YFC0604200)the Ministry of Science and Technology of the the International Geoscience Programme(IGCP675),which is a joint endeavor of UNESCO and IUGS.
文摘The newly discovered medium-scale Huangling uranium deposit is located in the Shuanlong area of the southeast Ordos Basin.This paper presents the systematic geochemical and zircon U-Pb studies on the Zhiluo Formation sandstones in the Huanling area.The data obtained play an important role in deducing the provenance and tectonic setting of the source rocks.The results show that the lower part of the Zhiluo Formation is mainly composed of felsic sedimentary rocks.The source rocks originated from a continental island arc environment in terms of tectonic setting.U-Pb ages of detrital zircons obtained can be roughly divided into three groups:170‒500 Ma,1600‒2050 Ma,and 2100‒2650 Ma.Based on the characteristics of trace elements and rare earth elements(REE)and the zircon U-Pb dating results,it is considered that the Cryptozoic Edo provenance of the Zhiluo Formation mainly includes magmatic rocks(such as granodioritic intrusions)and metamorphic rocks(such as gneiss and granulite)in the orogenic belts on the northern margin of the North China Plate and in the Alxa Block.Based on sedimentological and petrological results,it can be concluded that the provenance of clastic sediments in the Zhiluo Formation was in north-south direction.The preconcentration of uranium is relatively low in the Lower Zhiluo Formation in the Huangling area.Meanwhile,the paleocurrent system in the sedimentary period is inconsistent with the ore-bearing flow field in the mineralization period,which restricts the formation of large-scale and super-large-scale uranium deposits and ore zones in the southeast Ordos Basin.The understanding of provenance directions will provide crucial references for the Jurassic prototype recovery and paleo-geomorphology of the Ordos Basin and the prediction of potential uranium reservoirs of the basin.
