Re-examination of three specimens from the Kanchenjunga Himal of Nepal via in situ Lu-Hf garnet geochronology yields evidence of multiple garnet growth events.Spot analyses from grain cores in two specimens define Pal...Re-examination of three specimens from the Kanchenjunga Himal of Nepal via in situ Lu-Hf garnet geochronology yields evidence of multiple garnet growth events.Spot analyses from grain cores in two specimens define Paleozoic regressions whereas analyses from grain rims in the same specimens define low-precision regressions consistent with the timing of Himalayan orogenesis.These dates contrast with previously published low dispersion,ca.290 Ma isotope dissolution(ID)Lu-Hf garnet dates for the same rocks.Modelling of Lu and spot age distribution in representative grains from the specimens examined yields calculated dates that approximate the Permian-age regressions through the original ID data.These findings demonstrate that it is possible to generate low dispersion ID Lu-Hf data from multigenerational garnet with significantly different-age growth events when approximately equal proportions of the different age reservoirs are included in multi-component aliquots.展开更多
文摘Re-examination of three specimens from the Kanchenjunga Himal of Nepal via in situ Lu-Hf garnet geochronology yields evidence of multiple garnet growth events.Spot analyses from grain cores in two specimens define Paleozoic regressions whereas analyses from grain rims in the same specimens define low-precision regressions consistent with the timing of Himalayan orogenesis.These dates contrast with previously published low dispersion,ca.290 Ma isotope dissolution(ID)Lu-Hf garnet dates for the same rocks.Modelling of Lu and spot age distribution in representative grains from the specimens examined yields calculated dates that approximate the Permian-age regressions through the original ID data.These findings demonstrate that it is possible to generate low dispersion ID Lu-Hf data from multigenerational garnet with significantly different-age growth events when approximately equal proportions of the different age reservoirs are included in multi-component aliquots.
