Zircon and titanite geochronology of the F(u|¨)rstenstein granite massif,Bavarian Forest,NW Bohemian Massif:Pulses of the late Variscan magmatic activity
作者单位：Institut fr Geowissenschaften
会议名称：《中国科学院地质与地球物理研究所2004学术年会》
会议日期：2004年
学科分类：070902[理学-地球化学] 0709[理学-地质学] 07[理学]
基 金：supported by the Deutsche Forschungsgemeinschaft(Si718/2-1)
关 键 词：Bavarian Forest Fiirstenstein Variscan granite zircon age
摘 要：The F(u|¨)rstenstein granite massif is the largest late Variscan granitoid body exposed in the Moldanubian basement of the Bavarian *** granite massif comprises different rock types,ranging from diorite to granite in *** study provides precise zircon and titanite ages,obtained by the U-Pb isotopic dilution and Pb-Pb evaporation methods,and Nd-Sr isotopic data on this *** dating constrains an intrusive sequence as following:Dioritic rocks crystallised about 334 to 332 Ma ago, earlier than the high-temperature peak stage of the Variscan metamorphism of the Moldanubian basement(325 to 320 Ma) in the Bavarian *** medium- to coarse-grained Tittling granite was emplaced about 10 Ma later,between 324 and 321 Ma,while the medium-grained Eberhardsreuth granite crystallised between 316 and 312 Ma,contemporaneously with the coarse-grained porphyritic Saldenburg *** from the dioritic rocks give U-Pb ages of about 321±4 Ma,indicating thermal resetting or crystallisation due to the intrusion of the Tittling *** diorites have initialε values of -1.3 to -2.9 and relatively low initial Sr/Sr ratios of 0.7056 to 0.7067,which suggest mantle contribution to melts or melting of young mafic lower *** granites have similar initialε values of -3.6 to -4.1 but show some variation in their Sr isotopic composition(initial Sr/Sr ratios of 0.7063 to 0.7074),probably indicating the involvement of crustal material in their genesis.