Significance of Deformational Features in Gold Exploration: A Case Study from Paramanahalli, Karnataka
摘要
Paramanahalli gold deposit is located approximately 7 km west of the Chitradurga Shear Zone (CSZ) within the Chitradurga Greenstone Belt (CGB) in Karnataka. CGB has undergone three major deformation phases. The first phase (D1) is characterized by isoclinal folding and the development of foliations within the meta sedimentary rocks. The regional “Chitradurga Fold” and N-S trending CSZ are the outcome of D2 deformation. During the third phase (D3) of deformation, the D1 and D2 structures were refolded into E-W trending warps and kink folds. Gold mineralization at Paramanahalli is confined within the altered, deformed metabasalt, Banded Iron Formation (BIF), and quartz veins. Folds and faults are the major deformational features, which are observed during fieldwork and within the megascopic samples. Microstructures such as strain fringes, rotation of foliation, mica fish, kink bands, micro folds, quartz pods, and pinching/swelling of veinlets infer ductile deformation. Brecciation of quartz and displacement of quartz-magnetite bands within the BIF are evidence of brittle deformation. Gold mineralization in Paramanahalli is associated with D2 deformation, where CSZ played an important role as a conduit for ore-bearing hydrothermal fluids. The detailed understanding of such types of deformational features can be useful to understand gold metallogeny within the CGB and provide valuable inputs for future exploration and resource discovery.