Open AccessStructural Control on Banded Iron Formation (BIF) and Gold Mineralization at Abu Marawat Area, Central Eastern Desert, Egypt
Author(s) -
Mohamed K. El-Shafei
Publication year - 2011
Publication title -
journal of king abdulaziz university-earth sciences
Language(s) - English
Resource type - Journals
eISSN - 1658-4317
pISSN - 1012-8832
DOI - 10.4197/ear.22-2.7
Subject(s) - sinistral and dextral , geology , shear zone , clockwise , fold (higher order function) , geochemistry , mineralization (soil science) , greenstone belt , shear (geology) , quartz , thrust fault , slip (aerodynamics) , seismology , fault (geology) , petrology , paleontology , tectonics , archean , mechanical engineering , soil water , soil science , engineering , physics , thermodynamics
Abu Marawat area is considered as a promising site forexploration of gold mineralization, where many ancient gold mines,hydrothermal alteration zones, and intervening quartz veins arepresent. This study is a field-based structural analysis that aims atrevealing the relationship between mineral occurrences and localstructural setting. The area is a part of a back-arc volcanosedimentarysequence associated with banded iron formation (BIF) that hasundergone extensive ductile and brittle deformation history. Thismultiple deformation is manifested by four phases. D1 and D2 are theproduct of compressional stresses and are expressed by F1, F2 and F3folds in low-grade regionally metamorphosed rocks. D1 was aprogressive deformational phase started with F1 folds, which in a laterstage were overprinted by F2 folds. It resulted from NW-SE-orientedpure shear and is associated with imbricate thrust stacks, whichcontrol the locations of listwanite bearing gold. NE-SW-orientedcompressive stress during D2 is displayed by F3-slip folds at the earlystage followed by N-S- to NW-trending dip-slip normal faults andrelated shear zones. Mineralized quartz veins (MQV) were developedpost-D2 and pre-D3. Folding and refolding in addition to thrustmovement play a significant role in shortening and thickening of theiron formation bands located at the summit of Gebel Abu Marawat. D3and D4 are expressed by brittle deformation. D3 is displayed byconjugate shear planes represented by sinistral-NW-oriented anddextral-NE–oriented strike-slip faults that led to the dislocation andredistribution of gold mineraliztion associated with both MQV andlistwanite. Barren quartz veins trending E-W were also developedalong gash fractures formed during this phase of deformation.