Abstract:
Integrated petrographic studies entailing quartz‐type analysis and zircon typologic
studies were carried out on sandstones of the Lower Devonian Accraian Formation
of southern Ghana to constrain their provenance and tectonic setting. The stratigraphic
succession of the Devonian Accraian Group consists mainly of sandstones in the Lower
Accraian Formation, shales in the Middle Accraian Formation, and sandstone–shale
intercalations in the Upper Accraian Formation. Systematic sampling of sandstones
was conducted in the Lower Devonian Accraian Formation. Modal petrographic analysis
indicates that the sandstones are quartz arenites with their framework grains
consisting on average of, 99.8% quartz, 0.14% lithics with little or no feldspars. They
are subangular to subrounded in shape. Modal mineralogy of the sandstones suggests
that they are of craton interior origin with an affinity to recycled orogenic provenance.
Quartz‐type analysis was used to unravel distinct characteristic features of the quartz
grain, namely its polycrystallinity, nonundulose, and undulose nature to constrain the
source rock. This pointed to multiple sediment supply from both a plutonic origin and
a medium‐ to high‐grade metamorphic terrain. Furthermore, a comprehensive zircon
typology study on 298 zircon grains indicate multiple provenances of calc‐alkaline
affinity. This study revealed that the Lower Accraian Formation sandstones probably
received sediment input from the Paleoproterozoic Birimian Basin granitoids and their
associated metasedimentary rocks and some additional supply from the
Neoproterozoic sedimentary rocks from the Volta Basin which are inclusive of sediments
derived from the Dahomeyide Belt of the Pan‐African Orogeny.
