A standard QFL count and a special count of quartz grains indicate that the Dunkard sandstones are rich in quartz and sedimentary and metasedimentary lithic fragments, but poor in feldspar and igneous lithic fragments. Plots of the Dunkard detrital mode on provenance diagrams reveal a separation of samples into two groups: a geographically restricted “northern” group and a more extensive “southern” group. This discrimination is consistent with paleocurrent and facies distribution data, which delineate two sources of sediment to the Dunkard basin: a dominant southeastern source and a subordinate northern source.
Northern sandstones are rich in nonundulatory, monocrystalline quartz, “stable” polycrystalline quartz, and sedimentary lithic fragments. These sandstones largely reflect a stable cratonic source wherein rocks were formed from multicycle sediments, some of which were ultimately derived from a low-lying craton of granite and/or high-rank metamorphic Precambrian rocks. Southern sandstones are enriched in mud rock and foliated, quartz-mica rock fragments, “unstable” polycrystalline quartz, and polycyclic, monocrystalline quartz reflecting a southeastern source terrane of mixed low-rank metamorphic and sedimentary lithology.
Comparison of the Dunkard detrital mode with modern sands from tectonic settings capable of producing uplifted terranes of supracrustal source rocks reveals that the Dunkard basin was a foreland basin that received sediment from both the adjacent foreland fold-thrust upland and from positive areas on the craton. Low to medium-grade metamorphic and recycled sedimentary detritus, shed from an orogenic highland, diluted contributions of supermature sedimentary and magmatic detritus from the continental lowlands.