Quartz is a major constituent of crustal rocks occurring as a mineral of primary or secondary origin in both sedimentary and crystalline rock types. In sedimentary rocks quartz be distinguished into i) extrabasinal quartz derived from weathering of continental crust and ii) intrabasinal authigenic quartz precipitated in-situ, post deposition. In crystalline rocks, quartz occurs as a primary component following crystallization from a melt or as fracture cement associated with dilatant, brittle deformation of the rock mass.
These different quartz types can be identified from their petrographic and geochemical characteristics and the continuous progress of in-situ micro-analyses and mapping allows integration of mineralogical, elemental and isotopic correlative analysis at the sub-micron level. This enables interpretation of the physico-chemical environment leading to quartz precipitation and crystallization providing data to build models of past geological events of local as well as global significance.
This presentation will provide examples of two case studies integrating cathodoluminescence and trace element mapping with spatially resolved stable isotope analyses in quartz that revealed geochemical information relevant for advancing the geological understanding of 1) silicon cycling in Proterozoic oceans and 2) conditions of advective fluid flow facilitating transport of molecular hydrogen through the upper crust.
