The Central Mineral Belt of Labrador consists of a belt of supracrustal rocks that occupies the northern foreland region of the Grenville Province of the Canadian Shield. Recent mapping in this belt has shown that the Proterozoic Croteau Group consists of two distinct sequences separated by an observed angular unconformity. It is therefore proposed that the name Croteau Group be abandoned and that the lower, Aphebian, marine sequence of sandstone, dolostone, slate, argillite, and mafic volcanic rocks be named the Moran Lake Group and that the upper, Helikian, continental sequence of conglomerate, tuffaceous sandstone, and a calc-alkalic volcanic assemblage be named the Bruce River Group.The Moran Lake Group underwent polyphase deformation, which has been assigned to the Hudsonian Orogeny, prior to deposition of the Bruce River Group around 1474 Ma. The Bruce River Group was intruded by a large granitic batholith, the Otter Lake Granite, for which a preliminary Rb–Sr isochron age of 1445 Ma has been obtained; this age correlates with the Elsonian magmatic event, an event well documented in northern Labrador. The Seal Lake Group, a Neohelikian (1278 Ma) sequence of quartzites, conglomerates, and intercalated mafic lava flows, was unconformably deposited upon the Bruce River Group and the Otter Lake Granite. During the Grenvillian Orogeny, the Bruce River and Seal Lake Groups were deformed together into a major easterly trending syncline. Deformation and metamorphism decrease across these groups to the north.The Bruce River Group forms part of the Labrador uranium area and hosts 14 known uranium occurrences. Occurrences are concentrated in the basal sandstones and conglomerates of the group, above the Aphebian–Helikian unconformity, and in ignimbrites and acid tuffs near the top of the group. No uranium occurrences are known from the Moran Lake Group except in fault-related fractures below the unconformity.

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The Murowa kimberlite field includes three diamondiferous kimberlite pipes (K1, K2, and K3) and multiple kimberlite dikes that have been emplaced into the Archean Chibi granite batholith north of the Limpopo belt in south-central Zimbabwe. Here we summarize the key aspects of the geology of the Murowa kimberlites from previous studies and integrate these findings with new structural data to interpret a structural model governing the locations, relative positions, and orientations of emplaced kimberlite. Key observations of drill core, thin section petrography, geochemistry, and mapping of exposed rocks at the Murowa diamond mine are summarized from previous work, and these data collectively form the basis for emplacement interpretations and threedimensional (3-D) geologic models of each body. Structural observations are used to interpret the presence of a km-scale tensile bridge hosting the Murowa kimberlites and suggest Murowa is an example of kimberlite emplacement into multiple, reactivated, preexisting near-surface structures at different orientations. We propose that the physical state of the ascending magma (% of gas, extent of phase separation) can dictate whether kimberlite is emplaced along preexisting structures or creates and intrudes new fracture networks in planes of weak horizontal stress. A reproducible age of ~526 Ma is determined for two coherent kimberlite dikes at K1, while an older Rb-Sr model age of ~543 Ma is calculated for a single dike from K2, though this result is of limited reliability due to potential disturbance of the Rb-Sr system due to phlogopite alteration. These results highlight potential problems with reported ages from kimberlite pipes.