The Selukwe Subchamber (SSC) of Great Dyke is the only subchamber that is bounded extensively by a greenstone belt (Shurugwi greenstone belt (SGB)) on the western side for approximately 25 km and Archean granitoids on the eastern side. The other subchambers of the Great Dyke are bounded on both sides by entirely granitoids. It is also the narrowest section of the entire Great Dyke (as narrow as 4 km). This study focuses on a borehole section (PAR11 borehole) that intersects anomalous stratigraphy of the upper Ultramafic Succession of the Great Dyke as well xenolithic fragments exposed on surface within the SSC. The extensive xenolith suite of mainly ultramafic fragments is found on the central western flank of the SSC. The stratigraphy of the PAR11 borehole comprises of peridotites overlain by pyroxenites with dominant mineralogy olivine and orthopyroxene and minor clinopyroxene, plagioclase and spinel. Comparison of the major and trace element geochemistry of PAR11 with the regular section of the sequence in close proximity reveals that the PAR11 sequence is more primitive with higher Mg# but similar REE patterns typical l of an enriched source or crustally contaminated source with LREE enrichment, HREE depletion and a slight negative Eu anomalies. The mineral assemblages and proportions of mineral phases in the PAR11 borehole indicates a similar composition to that which formed the regular sequence of the Great Dyke but stratigraphically displaced indicating crystallization of a distinctly separate entity interpreted as feeder conduit. This anomalous occurrence on the east side contrasts with the extensive xenolith suite on the west side which also disrupts the normal layered sequence. The main rock types in the ultramafic-mafic xenolith suite are peridotite, pyroxenite and gabbro. The origin of some of these enclaves cannot be attributed to their derivation from the SGB because they are not present in the observed greenstone stratigraphy. Major and trace elements show a wide range of compositions which are dissimilar to both PAR11 and the general Great Dyke stratigraphy. REE patterns show depletion of LREE with relatively flat HREEs indicating a different magma to that which gave rise to the Great Dyke. These xenoliths do not have mineral compositions that are similar to the Great Dyke and therefore precludes them as having been derived from the Great Dyke Marginal Facies, a possible source of such rocks. This group of xenoliths were therefore inherited from a currently unknown source or reflect an unknown component of the SGB. Quartzites and banded iron formations (BIFs) that have also been observed in the xenolith suite but located at the top of the Great Dyke Mafic Sequence in this area and most likely reflect the roof lithologies to the SSC. In that case, the quartzites were derived from the Mont d’Or and Wanderer Formations while the BIFs are from the Upper Greenstones.