Geology of the Northwest Territories province from dikes and mafic lava flows, overlain by deep ocean turbidite deposits. These rocks are believed to be the remains of oceanic crust that ended up preserved, surrounded on all sides by felsic volcanic rocks and granitoid plutons. In the area of Snofleld Lake in the northern part of the Slave Province, the remains of Archean stromatolites are preserved in a dolomite unit between felsic volcanic and greywacke-mudstone turbidites, some of the earliest evidence of life, forming in the shallows around volcanic islands. Around 1.27 billion years ago in the Proterozoic, a series of major magmatic events affected the
Ringing rocks of symmetry. The overall geometry is cylindrical, with an average diameter of one kilometer. The pluton consists of two major units: an inner core of quartz-bearing felsic units with a diameter of 600 meters and an outer mafic unit composed of coaxial concentric layers. In map view, the complex has a bulls-eye configuration. The outer zone of the pluton consists of two alternating mafic hybrid rock types. In chemical analysis the rocks are nearly identical; however, the early stage minerals, olivine and pyroxene, were preserved in one and not the other, giving the rocks sharply different weathering properties. The rock