کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
9522678 1634961 2005 15 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Kinetics of antigorite dehydration: A real-time X-ray diffraction study
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات علوم زمین و سیاره ای (عمومی)
پیش نمایش صفحه اول مقاله
Kinetics of antigorite dehydration: A real-time X-ray diffraction study
چکیده انگلیسی
Antigorite dehydration has been studied in situ using time-resolved X-ray diffraction (XRD) in the 1.1-5.5 GPa pressure range. The sequence of XRD spectra reveals that the high-temperature stability limit of antigorite is decreased by 50-100 °C under H2O-unsaturated conditions. The decomposition of antigorite into the high-temperature products, forsterite + enstatite, proceeds via an intermediate assemblage of forsterite and a “talc-like” phase, observed within a temperature interval of 130 ± 20 °C. The analysis of the transformation-time data using the Avrami model suggests that the breakdown of antigorite and the “talc-like” phase is kinetically controlled by surface growth processes at the edges of grains. The overall transformation rates are 10 to 100 times faster than those observed in water-saturated experiments, and show that the H2O activity is a strong driving force for dehydration. The breakdown of antigorite in subducting oceanic mantle with such kinetics would result in a fluid discharge rate of the order of 10− 6 to 10− 8 s− 1. This is faster than the viscous relaxation of serpentinites, and could lead to brittle failure or weakening of pre-existing faults. This provides an explanation for the seismicity in the lower plane of double seismic zones.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Earth and Planetary Science Letters - Volume 236, Issues 3–4, 15 August 2005, Pages 899-913
نویسندگان
, , , , , ,