Lamprophyres, gold and orogenies: a mineral systems perspective

Abstract

The common spatial and temporal association of calk alkaline lamprophyres with orogenic gold deposits has been recognized for more than a century, although interpretations regarding the significance of this association have varied greatly. A persistent lack of consensus on Archean geodynamics and the deposits themselves presented a challenge to the use of a Mineral Systems approach, given that models should strive to encompass a source to sink understanding of deposit generation. Lamprophyres helped to resolve these issues because the compositions of the most primitive examples establish firm constraints on deep crustal and upper mantle regimes at the time of deposit formation, despite not being directly related to mineralization. Following the initial contribution of lamprophyres toward a coherent model of mineralization, numerous workers provided the important observations and refinements that have resulted in a robust Mineral Systems model for the deposit type. The discovery of diamonds in gold-associated lamprophyres, and circumstantial evidence that this association has been long-lived and widespread, presents opportunities to further refine orogenic gold models.