نتایج جستجو برای: metamictization
تعداد نتایج: 23 فیلتر نتایج به سال:
X-ray measurements were carried out in order to study the spontaneous radiation effects of alianite, gadolinite and monazite on their structures. It was found that the first two gave the experimental evidences of either expan sions from or destruction of their normal lattice structures, while the last one showed lattice expansion only. Heat treatments of these minerals in the vacuum caused them...
thoritc and, from the results of infra-red absorption spectra, concluded that this material contained (oH) groups; however, Mumpton and Roy (1961) in their experiments found no evidence in support of this substitution. rn the course of an extensive study of granitic pegmatites in yugoslavia, M. Risti6 and s. Pavlovi6 found in a pegmatite from prokuplje area, Serbia, zircon crystals associated w...
We report a near-infrared Fourier-transform (FT) Raman spectroscopic method to characterize the electronic transitions of U ions and the alpha-decay damage in natural zircon. The application is demonstrated by analyzing metamict and annealed zircons from Sri Lanka. The data from crystalline zircon reveal a relatively sharp spectral feature appearing near 2733 cm in Stokes spectra with a laser e...
We have investigated U-Pb discordance and oxygen isotopic composition of zircon using high– spatial resolution !O measurement by ion microprobe. !O in both concordant and discordant zircon grains provides an indication of the relationship between fluid interaction and discordance. Our results suggest that three characteristics of zircon are interrelated: (1) U-Pb systematics and concomitant age...
Zircon (U-Th)/He thermochronometry is an established radiometric dating technique used to place temporal constraints on a range of thermally sensitive geological events, such as crustal exhumation, volcanism, meteorite impact, and ore genesis. Isotopic, crystallographic, and/or mineralogical heterogeneities within analyzed grains can result in dispersed or anomalous (U-Th)/He ages. Understandin...
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