@article{oai:nagoya.repo.nii.ac.jp:00001411, author = {Suzuki, Kazuhiro and Adachi, Mamoru and Kajizuka, Izumi}, journal = {The Journal of earth and planetary sciences, Nagoya University}, month = {Dec}, note = {This is a data-set paper, listing a total of 1052 electron microprobe ThO_2,UO_2 and PbO analyses of monazites from gneiss and granitoid samples in the Ryoke metamorphic belt, Southwest Japan (Table 1). On the basis of these data, we have estimated the duration for the peak stage of the Ryoke metamorphism and evaluated diffusion parameters for Pb in monazite (Suzuki et al., 1994). The principal results are : (1) Two samples of psammitic gneiss contain detrital monazites whose CHIME ages date back to the Precambrian as old as 1700 Ma. Several detrital grains are immune from overgrowth during the Ryoke metamorphism, and show marginal Pb-loss by diffusion from the surface. The width of the diffusion rims range 18-22μm for grains in the sample of the andalusite-sillimanite transition zone (620℃) and 48-58μm for those in the sample of the sillimanite-orthoclase zone (680℃).(2) The temperature-time relation of the Ryoke gneiss are (a) first attainment of the amphibolite facies conditions (525±25℃) at 98.8-98.0 Ma, (b) peak metamorphism at 95.2±3.9 Ma, and (c) subsequent retrogression to 500° at 90 Ma and to 300℃ at 84 Ma.(3) The Pb diffusion coefficients, calculated from the observed Pb profiles on the assumption of an isothermal step of 5 Ma duration, are 1.9(±0.3)×10^<-21>cm^2/sec for 620℃ and 1.5(±0.3)×10 ^<-20>cm^2/sec for 680℃. These data yielded an activation energy of 2.44(+2.85/-1.26)×10^5 J/mol and a frequency factor of 3.4×10^<-7>(8.5×10^<-12>-2.2×10^7)cm^2/sec for Pb diffusion in monazite., 国立情報学研究所で電子化したコンテンツを使用している。}, pages = {75--81}, title = {Th, U and Pb analytical data of monazites used in the paper ”Electron microprobe observations of Pb diffusion in metamorphosed detrital monazite”}, volume = {41}, year = {1994} }