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Regional Geology


The Rottenstone Property lies within the Rottenstone domain of the Proterozoic Trans-Hudson orogenic belt. The Rottenstone domain is described as a northeast trending arcuate tonalite-migmatite belt. This belt lies between the plutonic rocks of the Wathaman batholith (1855±6 Ma) to the northwest and the metavolcanic-metasediment rocks and granitoid plutons of the La Ronge domain to the southeast.

The Property bedrock geology is dominated by northeast striking, northwest dipping meta-tonalite-trondjhemite-pelitic migmatite complex of Paleoproterozoic age. The metamorphic grade of the Rottenstone domain is mid-upper amphibolite. Petrographic analysis of drill core (Uravan 1999) concurs with this observation and also suggests that metamorphic conditions may have reached lower granulite facies.

Stratigraphy


The local geology / stratigraphy as defined by available drill logs, property scale mapping and most recent 2003 – 2005 government of Saskatchewan mapping at Rottenstone, is complex. MacLachlan (2003-2005) divided the immediate Rottenstone property area into 2-phase granitoids and supracrustal rocks. The granitoids are mapped as pre strong foliation (Smain) and post strong foliation and comprise granitoid pre Smain dominated by granodiorite to monzogranite with minor diorite, tonalite and quartz monzonite. Post Smain granitoids consist of white to pink tonalite to monzogranite that contain abundant metasedimentary xenoliths and schlieren. The supracrustal rocks, the oldest rocks, include pelitic to psammopelitic migmatites with in situ leucosome, biotite-hornblende-plagioclase, melanocratic metasedimentary / metavolcanic rocks and amphibolite. The ultramafic intrusions; host to the Rottenstone deposit and the Tremblay-Olson showing, occur within metasedimentary rocks (the supracrustal rocks).

Structure


Structurally, the history of the Rottenstone Domain is complex and the particulars of the structural events have been masked by the formation of the migmatite complex. MacLachlan (2003-2005) discusses various fold types with northeast-striking axial planes. Also, it is very obvious from LandSat images and from available regional geophysical data (MAG) the property area is cut by several northwest – southeast structural lineaments suggestive of deep rooted multi-phase faults and shears. A very significant fault (Fraser Fault) striking northeast and dipping 15° to the northwest was recognized by drilling in the Rottenstone deposit area. The Rottenstone deposit sits in the immediate hanging wall of the fault; the fault could be the conduit for the ultramafic host; or, possibly truncates the deposit suggesting there should be more Rottenstone-type mineralization in the footwall of the fault. The fault has been interpreted as a reverse fault hence the continuation of Rottenstone, if it is in the footwall, should be at depth.