Chemical composition of rock-forming minerals in gold-related granitoid intrusions,southwestern New Brunswick,Canada: implications for crystallization conditions,volatile exsolution,and fluorine-chlorine activity |
| |
Authors: | Email author" target="_blank">Xue-Ming?YangEmail author David?R?Lentz |
| |
Institution: | (1) Department of Geology, University of New Brunswick, PO Box 4400, Fredericton, NB, Canada, E3B 5A3;(2) Present address: INCO Technical Service Ltd., Exploration, Highway 17 West, Copper Cliff, ON, Canada, P0M 1N0 |
| |
Abstract: | Chemical composition of rock-forming minerals in Appalachian Siluro-Devonian granitoid intrusions, southwestern New Brunswick,
was systematically determined by electron microprobe. The mineral chemical data together with petrographic examination was
used to test magmatic equilibration and to constrain crystallization conditions, volatile exsolution, and fluorine-chlorine
activity of fluids associated with these intrusions. Mineralogical distinction between Late Silurian to Early Devonian granodioritic
to monzogranitic series (GMS) and Late Devonian granitic series (GS) rocks is evident, although both are subsolvus I-type
to evolved I-type granitoids. Oxidized to reduced GMS rocks consist of quartz, plagioclase (An>10), K-feldspar, biotite, apatite,
titanite, zircon, monazite, ± hornblende, ± pyroxene, ± magnetite, ± ilmenite, and ± sulfide. GS rocks comprise quartz, K-feldspar,
plagioclase (An<10), mica group minerals, zircon, monazite, apatite, sulfide, ± ilmente, ± magnetite, ± topaz, ± columbite,
and ± xenotime. Inter-intrusion and intra-intrusion variations in mineral chemistry are interpreted to reflect petrogenetic
processes (e.g., assimilation and fractional crystallization) during granitoid evolution. Although magmatic equilibration
among rock-forming minerals are disturbed by subsolidus hydrothermal processes, GMS rocks appear to have higher magmatic temperatures,
variable levels of emplacement, a range of
(i.e., reduced intrusions 10−16.7∼10−13.4 and oxidized intrusions 10−14.0∼10−10.5 bars), and relatively low f
HF/f
HCl ratios (10−3.0∼10−1.0) in exsolved fluids, compared to GS rocks. Reduced GMS intrusions bear higher gold potential and thus may be prospective
targets for intrusion-related gold systems.
Electronic Supplementary Material Supplementary material is available for this article at |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|