Silica Diagenesis in the Marcellus Shale: A Trace Element and Hyperspectral Cathodoluminescence Study
C. Delle Piane, C. MacRae, N. Wilson, A. Torpy and D.N. Dewhurst
Event name: Sixth EAGE Shale Workshop
Session: Poster Session 1
Publication date: 28 April 2019
Info: Extended abstract, PDF ( 1.61Mb )
Price: € 20
Quartz is one of the major constitutive minerals of sedimentary rocks and its abundance in shales is thought to have a significant control on their mechanical properties as well as on the efficiency of hydraulic fracturing stimulation. While mineralogy based estimations of the strength and deformation behaviour (brittle or ductile) of shales are commonly used in practical applications, it should be noted that they do not account for parameters like phase distribution and cementation that also affect mechanical and elastic properties. Quartz in shales and can occur in at least two forms: i) as a detrital component and ii) as an authigenic mineral precipitated during diagenesis. In this study, we present high resolution scanning electron microscopy (SEM)-cathodo-luminescence (CL) imaging of authigenic quartz combined with Electron Probe Micro-Analysis (EPMA) trace-element quantification at sub-micron spatial resolution in samples from the Marcellus Shale of NE Pennsylvania, USA. For the first time the geochemistry of authigenic quartz in shales is presented and discussed in relation to the silica source and conditions of precipitation.