کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5788810 | 1414272 | 2017 | 10 صفحه PDF | دانلود رایگان |
Geochronological investigation on gneisses of granitic to leucogranitic compositions in Cuona, south Tibet, reveal that their protoliths formed at 808.8 ± 7.9-816.4 ± 3.4 Ma and 855.8 ± 7.0 Ma, respectively. Zircon rims from the granitic gneiss record a metamorphic age of 739.4 ± 4.3 Ma. Lu-Hf isotopic analyses on zircon grains with Neoproterozoic ages yield negative εHf(t) values from â9.0 to â4.2, and the corresponding two-stage Hf model ages are 1965-2228 Ma. Whole-rock geochemical data indicate that all granitic gneisses are K-riched calc-alkali series. These new data together with literature data show that (1) the Himalayan terrane experienced an episode of Neoproterozoic magmatism at 850-800 Ma; (2) the Neoproterozoic magma of granitic compositions were derived from partial melting of ancient crusts, possibly due to the thermal perturbation related with the breakup of the Rodinia supercontinent.
Journal: Science Bulletin - Volume 62, Issue 6, 30 March 2017, Pages 415-424