Fourty-four isotopic ages have been determined by K-Ar and U-Th-Pb methods for late Palaeozoic granites in Nan Ling Region,South China.All dating values variate within the ranges of 231-348 m.y.From the obtained dates...Fourty-four isotopic ages have been determined by K-Ar and U-Th-Pb methods for late Palaeozoic granites in Nan Ling Region,South China.All dating values variate within the ranges of 231-348 m.y.From the obtained dates,further evidence has been found that there do exist late Palaeozoic granites, which can be subdivided into late Devonian and Permian granites. Within the late Devonian terrain, there is a granitic intrusive, namely granodiorite with zircon U-Th-Pb age of 348 m.y.,while ten granitic intrusives have been recognized within the Permian terrain where granites are predominant, yielding biotite K-Ar age of 236-289 m.y. (λβ= 4.72 ×10^-10y.^-1,λR=5.57×10^-11y.^-2) and zireon U-Th-Pb age ranging from 231--280 m.y.respeetively. It is obvious from the dates that intrusive activities if granitic magma extensively took place in Nan Ling re,on during the late Palaeozoic, although no records of orogenic movements have been found, indicating that the faulta are the main factor controlling the activities of granitic magma, whereas the orogenic movements are not the only prerequisite to the formation of granitic magma, and the intrusive activities.展开更多
109 isotopic ages have been determined and collected in the recentten years, Most of them belong to Yenshanian, within which an early period (140--180m.y.) and a mid.late period (120-130m.y.) are distinguished. Granod...109 isotopic ages have been determined and collected in the recentten years, Most of them belong to Yenshanian, within which an early period (140--180m.y.) and a mid.late period (120-130m.y.) are distinguished. Granodiorite is predominant in early Yenshanian, and the related ore deposits are mainly of skarn character with mesothermal vein fillings being secondary in importance. During the mid-late Yenshanian, granite prevails and are accompanied by iron mineralization. From early to mid-late Yenshanian, the magmatie activity exhibites a striking regularity of variation in composition from intermediateacid servations, indicate that pegmatites in the Tanba region are related to Caledonian migmatization and have been reworked by two separated events at 120--130 m.y. (northern zone) and 70--80m.y. (southern zone) respectively. The migmatization progress has resulted in the formation of muscovite and biotite, thus offering an important eluc to the genesis of industrial muscovite. Three episodes of magmatic emplacement (590--720 m.y., 800-900 m.y., and more than 960 m.y.) in late Proterozoic times are also reeognized in this region.展开更多
文摘Fourty-four isotopic ages have been determined by K-Ar and U-Th-Pb methods for late Palaeozoic granites in Nan Ling Region,South China.All dating values variate within the ranges of 231-348 m.y.From the obtained dates,further evidence has been found that there do exist late Palaeozoic granites, which can be subdivided into late Devonian and Permian granites. Within the late Devonian terrain, there is a granitic intrusive, namely granodiorite with zircon U-Th-Pb age of 348 m.y.,while ten granitic intrusives have been recognized within the Permian terrain where granites are predominant, yielding biotite K-Ar age of 236-289 m.y. (λβ= 4.72 ×10^-10y.^-1,λR=5.57×10^-11y.^-2) and zireon U-Th-Pb age ranging from 231--280 m.y.respeetively. It is obvious from the dates that intrusive activities if granitic magma extensively took place in Nan Ling re,on during the late Palaeozoic, although no records of orogenic movements have been found, indicating that the faulta are the main factor controlling the activities of granitic magma, whereas the orogenic movements are not the only prerequisite to the formation of granitic magma, and the intrusive activities.
文摘109 isotopic ages have been determined and collected in the recentten years, Most of them belong to Yenshanian, within which an early period (140--180m.y.) and a mid.late period (120-130m.y.) are distinguished. Granodiorite is predominant in early Yenshanian, and the related ore deposits are mainly of skarn character with mesothermal vein fillings being secondary in importance. During the mid-late Yenshanian, granite prevails and are accompanied by iron mineralization. From early to mid-late Yenshanian, the magmatie activity exhibites a striking regularity of variation in composition from intermediateacid servations, indicate that pegmatites in the Tanba region are related to Caledonian migmatization and have been reworked by two separated events at 120--130 m.y. (northern zone) and 70--80m.y. (southern zone) respectively. The migmatization progress has resulted in the formation of muscovite and biotite, thus offering an important eluc to the genesis of industrial muscovite. Three episodes of magmatic emplacement (590--720 m.y., 800-900 m.y., and more than 960 m.y.) in late Proterozoic times are also reeognized in this region.
