Rocky Mountain (56th Annual) and Cordilleran (100th Annual) Joint Meeting (May 3–5, 2004)

Paper No. 6
Presentation Time: 8:00 AM-5:00 PM

THE GEOLOGY, ALTERATION AND MINERALIZATION OF THE TRUE NORTH GOLD DEPOSIT, FAIRBANKS DISTRICT, ALASKA


CAMPBELL, Keith B., Center for Research in Economic Geology, Univ of Nevada, Reno, Mail Stop 169, Reno, NV 89557-0232, kbc@unr.edu

Kinross Gold Corporation’s True North Mine is located in the Fairbanks District, central Alaska approximately 18 kilometers northwest of the Fort Knox Mine and about 30 kilometers northeast of Fairbanks, Alaska. The True North deposit is hosted by the Chatinika sub-terrrane of the Yukon-Tanana Terrane. The Chatinika sub-terrane at the True North deposit consists of generally high-grade metamorphic rocks that include eclogite, biotite schist, biotite-quartz schist, amphibolite, quartzite, and marble. These high grade rocks were thrust over the lower grade Fairbanks Schist that makes up of bulk of the Yukon-Tanana terrane in the Fairbanks district. The Chatinika sub-terrane has undergone several regional deformational events resulting in a complexly folded and re-folded section that was mineralized along high and low-angle faults. The low angle faults appear to be sub-parallel to and related to the thrust fault that emplaced the Chatinika sub-terrane over the Fairbanks Schist. High angle faults in the True North mine appear to be sub-parallel to a series of NE-striking left lateral to left lateral oblique faults that offset lithologic units in the Fairbanks District, including the Chatinika sub-terrane. A later set of high angle faults of variable orientation offset the mineralization. Veins of quartz, quartz-stibnite, ± arsenopyrite and pyrite, and several generations of carbonate are found within the mineralized zones. Alteration consists of a halos of silica-carbonate (fuchsite-ankerite ± arsenopyrite) around veins and a broader area of graphite introduction along foliation in biotite schists and along faults.