STRUCTURAL ANALYSIS OF THE FOXE FOLD BELT, MELVILLE PENINSULA, NUNAVUT, CANADA

The nature and vergence of folds of the Paleoproterozoic Foxe Fold Belt (FFB) of Melville Peninsula was investigated. Preliminary structural data, based on field mapping in the summer of 2009, are presented. The FFB is exposed in Melville Peninsula and Baffin Island. In Melville Peninsula, the FFB interfolds Paleoproterozoic Penrhyn Group metasedimentary rocks with their underlying Archean basement gneisses of the Prince Albert Group. A separate, older Archean terrane, the Repulse Bay Block, is exposed immediately south of the FFB and ~10-15 km south of the southernmost exposures of the Penrhyn Group. The Penrhyn Group may have been extruded to the north during collision between the Repulse Bay Block and the Prince Albert Group that was responsible for the formation of the FFB. The Penrhyn Group is a passive margin sequence and consists of amphibolite-facies pelitic and psammitic gneiss, calc-silicate gneiss interbedded with marble, massive marble, and minor amphibolite. The Prince Albert Group consists of ~2.76-2.70 Ga supracrustal rocks and associated granitoids. Henderson (1983) interpreted transport within the FFB as top-to-the-WSW, parallel to the trend of the orogen, based on the orientations of sheath folds. However, transport in the FFB of Baffin Island is interpreted as top-to-the-north, based on north-verging folds and the geometry of thrust faults. We conducted detailed structural analysis of folds in the FFB in Melville Peninsula to investigate the transport direction and kinematics of the fold belt.

In general, the structure is dominated by large-scale, shallowly plunging, NNW-verging folds that trend ~250° and tighten toward the WSW. Small-scale isoclinal folds are typically parallel or sub-parallel to the orientation of these larger scale folds. Rare evidence exists of earlier isoclinal folds with hinge lines trending ~260°, or ~10° north of the ~250° trend of the NNW-verging folds. The obliquity between the two fold hinge line orientations is visible in the hinge areas of the NNW-verging folds. The results suggest the general transport direction in the FFB of Melville Peninsula was toward ~340° with possible earlier transport toward ~350°. These results are generally consistent with the interpreted northerly transport direction in the FFB of Baffin Island.