Central Slave basement complex The Central Slave basement complex (CSBC) is the
basement under the central and western part of the craton. The CSBC's eastern extent is unknown, as its disappearance is marked by Nd and Pb isotopic boundaries. The Acasta gneisses are geochemically similar to other Archaean complexes but, four billion years old, they contain even older zircon cores. These cores indicate that the parental magmas of such complexes formed by interaction between the zircon-bearing crust and mantle-derived melts. No such older Acasta gneisses have been discovered yet, but the zircon cores indicate they could exist.
Back River volcanic complex The
Back River volcanic complex is an Archaean
stratovolcano preserved in an upright position surrounded by four sedimentary sequences reflecting the volcano's magmatic history. An exposed dome in the southern half of the complex is interpreted to be the eroded portion of the volcano. In contrast to the remaining craton, the complex has only undergone a low degree of deformation.
Yellowknife Supergroup The Yellowknife Supergroup, also known as the Yellowknife
greenstone belt, was deposited over 300 million years from ca. 2.9-2.6 Ga, and directly overlies the CSBC including much of the Eastern Slave Province. The CSBC and the Yellowknife greenstone belt are separated by a distinct unconformity that is laterally continuous over hundreds of kilometres. The Yellowknife Supergroup has been exposed to major metamorphism around 2605 Ma resulting in a range of
greenschist to lower
amphibolite facies. The Supergroup contains at least four distinct sequences representing different tectonic environments, deposited in separate intervals. The four main sequences include from oldest to youngest, the Central Slaver Cover Group, Kam Group, Banting Group, and Jackson Lake Formation. The Yellowknife Supergroup has been used to represent the general stratigraphy of the greenstone belts in the Slave Craton, including belts in the Eastern Slave, in order to interpret the processes involved in the evolution of the Slave Craton.
Central Slave Cover Group The Neoarchean supracrustal sequence known as the Central Slave Cover Group (informally Dwyer Group) is a 2.9–2.8 Ga package of
fuchsitic quartzites overlain by
banded iron formations. This fuchisitic quartziite sequence seems to be characteristic of many other cratons between about 3.1 and 2.8 Ga and marks a global peak in quartzite production. The Central Slave Cover Group is typically 100 to 200 meters thick. A quartz pebble conglomerate found at the base of the Central Slave Cover Group marks a distinct unconformity that is laterally continuous over much of the CSBC. This quartz pebble conglomerate layer has been found as far northwest as the 4.03 Ga Acasta Gneiss Complex. The Central Slave Cover Group is autochthonous and represents a single continuous cover sequence, that links the basement complex in the northwest with the basement in the south-central Slave Province. Uniform, laterally continuous deposition implies that the CSBC was previously a part of a single ancient craton that existed as early as 2.85 Ga.
Kam Group The Kam Group is a 0.3–6 kilometre thick sequence that overlies banded iron formations of the Central Slave Cover Group. The contact between these two groups is not well preserved due to the intrusion of gabbro sills and moderate shearing. The Kam group is separated into a lower and upper group based on the existence of a thin felsic volcaniclastic layer (Ranney Chert) dated at 2722 Ma. The lower Kam group consists of the Chan Formation which contains flows of pillowed basalts intruded by a series of gabbroic sills and dikes that were produced in an extensional back-arc basin setting. Sedimentary rocks exposed in the northern part of the formation are between 2.84 and 2.80 Ga. The Upper Kam Group contains three formations deposited between 2772 and 2701 Ma. It is composed mainly of intermediate and basaltic volcanic rocks with thin intercalated rhyolite tuff layers and minor
komatiite flows. Rocks in this formation were seemingly formed in an arc environment and may be a result of rifting of basement rocks due to increased mantle plume activity.
Banting Group The Banting group is a north-striking sequence that is faulted overtop of the older Kam Group and younger Jackson Lake Formation. The contact between the lower units and the Banting Group is a disconformity that represents a ~40 million year gap in deposition. The Banting Group contains siliceous to intermediate volcanic rocks that are typically calk-alkalic. The Banting Group formation is largely a result of post 2.7 Ga volcanism and sub-volcanic activity. A series of 2658 Ma quartz-feldspar intrusions are found throughout the underlying Kam group that are related to the post 2.7 Ga volcanism found in the Banting Group.
Jackson Lake Formation Deposition of the Jackson Lake Formation began at 2605 Ma. The formation is a high energy sedimentary deposit that overlies the volcanic rocks of the Kam Group. The deposit consists of polymict conglomerates and fluvial sandstones that have been subjected to a major metamorphic event as evident by similarly oriented vertical dips and lineations found in older groups. == Evolution of Slave Craton ==