Experimental evidence regarding the pressure dependence of fission track annealing in apatite

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• 作者：J.S. Schmidt^a ; ^{jaques.schmidt@ufrgs.br" class="auth_mail} ; M.L.M.V. Lelarge^a ; R.V. Conceicao^a ; N.M. Balzaretti^b
• 关键词：fission track ; annealing kinetics ; pressure ; apatite ; temperature ; thermochronology
• 刊名：Earth and Planetary Science Letters
• 出版年：15 March, 2014
• 年：2014
• 卷：390
• 期：Complete
• 页码：1-7
• 全文大小：793 K

文摘

The main purposes of fission track thermochronology are unravelling the thermal histories of sedimentary basins, determining uplift and denudation rates, identifying the structural evolution of orogenic belts, determining sedimentary provenance, and dating volcanic rocks. The effect of temperature on fission tracks is well known and is used to determine the thermal history; however, the effect of pressure on the stability of tracks is still under debate. The present work aims to understand the role of pressure on the annealing kinetics of apatite fission tracks. The samples of Durango apatite used in our experiments were chosen for their international recognition as a calibration standard for geological dating. Neutron irradiation of the samples, after total annealing of their spontaneous tracks, produced induced tracks with homogeneous densities and lengths. The effect of pressure associated with temperature on fission track annealing was verified by experimental procedures using a hydraulic press of with a toroidal chamber profile. The experiments consisted of a combination of applying with for . The annealing rate was analysed by measuring the lengths of the fission tracks after each experiment using optical microscopy. The results demonstrate that the annealing of apatite fission tracks has a pressure dependence for samples subjected to . However, when extrapolated to pressures of , compatible with the normal geological context in which apatite fission track methodology is broadly used, this dependence becomes insignificant compared to the temperature effect.