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| Author(s): |
Eduardo Augusto Campos Curvo
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Física Gleb Wataghin |
| Defense date: | 2005-12-13 |
| Examining board members: |
Julio Cesar Hadler Neto;
Koji Kawasjita;
Sérgio Roberto de Paulo;
Ernesto Kemp;
José Augusto Chinellato
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| Advisor: | Julio Cesar Hadler Neto |
| Abstract | |
Epidote fission-track ages for samples from the Serra da Mantiqueira were obtaine via both Population an External Detector Methods (EDM) an the mean value was (201 ± 15) Ma. The ages showe internal consistency an are place between those obtained through apatite, (127 ± 10) Ma, and the zircon fission-track dating, (369 ± 15) Ma. Studies concerning the epidote fission track annealing were also performed. The annealing curves were obtaine for annealing times of 10, 100, 100 hours an temperatures ranging from 340 to 850 ºC. The curve of reduce ensity is closest to that proposed by Naeser et al.(1970), which has estimate a closure temperature of 630 ºC (1 Ma). The curve of reduce length,also measured, is the first of this kin obtaine for epidote. The fitting of the length ata, performe by using the model propose by our Group, conducted to a partial annealing zone (PAZ) with borders at 411 an 544 ºC for 1 Ma. These values place epidote PAZ above the estimate PAZ for apatite an zircon. Three measurements of the efficiency factor (g), necessary to perform EDM, were carrie out. Those measurements conducted to the value 1.06 ± 0.08 (1s), which differs from those found for others minerals (0.684 ± 0.012 for zircon; 0.601 ± 0.023 for titanite an 0.549 ± 0.015 for apatite). The value of g obtained to epidote means that even in 4 p geometry the mineral registers two times less tracks than the muscovite mica (2 p geometry) (AU) | |