کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
8911606 | 1638619 | 2018 | 71 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Pyrite deformation and connections to gold mobility: Insight from micro-structural analysis and trace element mapping
ترجمه فارسی عنوان
تغییر شکل پریت و اتصالات به تحرک طلا: بینش از تجزیه و تحلیل میکرو ساختاری و نقشه برداری عنصر
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
ژئوشیمی و پترولوژی
چکیده انگلیسی
The metamorphic transition of pyrite to pyrrhotite results in the liberation of lattice-bound and nano-particulate metals initially hosted within early sulphide minerals. This process forms the basis for the metamorphic-driven Au-upgrading model applied to many orogenic Au deposits, however the role of syn-metamorphic pyrite deformation in controlling the retention and release of Au and related pathfinder elements is poorly understood. The lower amphibolite facies metamorphic mineral assemblage (Act-Bt-Pl-Ep-Almâ¯Â±â¯Calâ¯Â±â¯Qzâ¯Â±â¯Ilm; 550â¯Â°C) of Canada's giant Detour Lake deposit falls within the range of pressure-temperature conditions (450â¯Â°C) for crystal plastic deformation of pyrite. We have applied a complementary approach of electron backscatter diffraction (EBSD) mapping and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) 2D element mapping on pyrite from the Detour Lake deposit. Chemical element maps document an early generation of Au-rich sieve textured pyrite domains and a later stage of syn-metamorphic oscillatory-zoned Au-poor pyrite. Both pyrite types are cut by Au-rich fractures as a consequence of remobilization of Au with trace element enrichment of first-row transition elements, post-transition metals, chalcogens and metalloids during a late brittle deformation stage. However, similar enrichment in trace elements and Au can be observed along low-angle grain boundaries within otherwise Au-poor pyrite, indicating that heterogeneous microstructural misorientation patterns and higher strain domains are also relatively Au-rich. We therefore propose that the close spatial relationship between pyrite and Au at the microscale, features typical of orogenic Au deposits, reflects the entrapment of Au within deformation-induced microstructures in pyrite rather than the release of Au during the metamorphic transition from pyrite to pyrrhotite. Moreover, mass balance calculations at the deposit scale suggest that only a small percentage of Au could have been sourced from pyrite and instead point to the role of substructures in pyrite as depositional traps for Au during syn-metamorphic deformation- and fluid-assisted diffusion Au-upgrading.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Lithos - Volumes 310â311, June 2018, Pages 86-104
Journal: Lithos - Volumes 310â311, June 2018, Pages 86-104
نویسندگان
R. Dubosq, C.J.M. Lawley, A. Rogowitz, D.A. Schneider, S. Jackson,