The Coldwell alkaline complex was intruded into rocks of the Schreiber-White River belt, during the Neohelikian Subera. The complex was emplaced in three distinct magmatic episodes, magmatic centers were displaced to the west with time. Block Faulting has disturbed the geometry of the major rock units in the western and central regions of the complex.
Syenitic rocks in the vicinity of Craddock Cove were formed by albitization of a monzonitic parent. A basaltic xenolith, several square kilometers in area, was block faulted into the syenite. Fracturing of the xenolith during its emplacement allowed contact metasomatism of the basalt.
Lamprophyre dykes associated with Center II magmatism, intrude the syenite. These dykes show evidence that they formed as a result of magma maxing at depth. Intrusion of the syenite by these dykes and petrographic features of the syenite, indicate it to be a Center I rock type.