M. Khanna et al., PETROGRAPHIC STUDY OF MARGINAL SEDIMENTS FROM THE ELK POINT GROUP OF NORTHWESTERN ALBERTA, CANADA, Bulletin of Canadian petroleum geology, 41(3), 1993, pp. 307-324
Primary mineralogy of the sandstones in the Devonian Elk Point Group w
as dictated by a predominantly granitic source area with minor metamor
phic and volcanic components. Extensive diagenesis involved dissolutio
n of feldspars and lithoclasts, precipitation of quartz, and a second
phase of dissolution of feldspar, lithoclasts and quartz. Analysis of
the clay fraction shows an absence of significant amounts of kaolinite
but an abundance of illite and chlorite. Later, authigenic calcite an
d dolomite precipitated in Elk Point sandstones, which were subsequent
ly further cemented by anhydrite. Cementation, especially by quartz, h
as considerably reduced the porosity in many places. Regional variatio
n in porosity is marked by high variability on meso- and micro-scales.
Authigenic calcite and dolomite are significant components but were s
ubjected to dissolution before a phase of anhydrite growth. Partial di
ssolution of anhydrite is evidence of the last event. Periods of flush
ing by meteoric-water affected early stages of diagensis with evaporit
ic brines prominent in mesogenesis.