Qualitative comparison of airborne resistivity with the geology of the Kiglapatt intrusion, Labrador

Abstract

The Kiglapait inlrusion is a Precambrian lopolithic layered igneous intrusion located on the Labrador coast. The intrusion is composed of five major rock types, delineated as zones: (1) Outer Border Zone (fine-grained ultramafic to anorthositic gabbros); (2) Inner Border Zone (coarse-grained olivine gabbro); (3) Lower Zone (troctolite); (4) Upper Zone (olivine gabbro to ferrosyenite); (5) Upper Border Zone (troctolite to ferrodiorite, with inverted stratigraphy). Both the Upper Zone and Upper Border Zone display relatively low resistivities in comparison with the remainder of the intrusion, these low values being due to the appearance of magnetite and pyrrhotite respectively in these areas. An examination of Upper Border Zone resistivities helps to confim1 the lopolithic shape of the intrusion. An arc of relatively low resistivity in the western portion of the Lower Zone also aids in this respect. However, the source of the anomalously low resistivity in this arc is not known. It may be speculated that the troctolite of the Lower Zone, which is of the same age as the troctol ite host of the nickel-copper-cobalt deposit at Yoisey Bay to the south, may also contain material of economic interest.