Textural mapping and building a paragenetic interpretation of hydrothermal veins

Abstract

Paragenetic interpretation, defined as the process of constraining the order in which the phases (minerals) comprising a rock formed, are fundamental in all disciplines requiring a detailed mapping of the genetic relationships between the investigated crystal(s) and their surrounding phases. Ore geology, geochronology, petrological and fluid inclusion studies are underpinned by a robust interpretation of the paragenesis. Without this understanding, the interpretation of the analytical data will be greatly restricted and potentially wrong. Textural mapping is particularly useful for studying phases precipitated into hydrothermal veins because the host many metallic ore deposits. Understanding the paragenesis and the association of ore minerals feeds directly into the approach taken towards exploration, mining operation and ore processing. Apart from ore deposits, precipitation of hydrothermal phases occurs in any setting where hot fluids interact with rock or sediment (e.g. CCS storage; geothermal facilities). This paper summarises the principles for developing a robust paragenetic interpretation, including demonstrating the practical workflow via a case study from a sulphide-bearing vein near Loch Tay, Scotland. The principles and the workflow outlined in this paper are applicable to any discipline and route of investigation that necessitates a robust understanding of the relationships of the phases in a rock.