File(s) under permanent embargo
Chemical composition and evolution of the garnets in the Astamal Fe-LREE distal skarn deposit, Qara-Dagh-Sabalan metallogenic belt, Lesser Caucasus, NW Iran
Almost all three garnet types have been replaced by fine-grained, dark-brown allanite that is typically disseminated and has the same relief as andradite. The Cu content increases while Ni content decreases slightly towards the rim of garnet II and garnet III. Copper in garnet II is positively correlated with increasing almandine content and decreasing andradite content, indicating that the almandine structure, containing relatively more Fe2 +, is more suitable than andradite and grossular to host divalent cations such as Cu2 +. Nickel in garnet II is positively correlated with increasing andradite content, total Fe, and decreasing almandine content. This is because Ni2 + substitutes for Fe3 + in the Y (octahedral) position. There are unusual discrete grossular-almandine rich domains within andraditic garnet III, indicating the low diffusivity of Ca compared to Fe at high temperatures.
History
Publication title
Ore Geology ReviewsVolume
78Pagination
166-175ISSN
0169-1368Department/School
School of Natural SciencesPublisher
Elsevier BVPlace of publication
NetherlandsRights statement
Copyright 2016 Elsevier B.V.Repository Status
- Restricted