Calcareous algae and associated microfossils from Mid-Carboniferous rocks in east-central Idaho

Abstract

Mid-Carboniferous (upper Chesterian–lower Atokan) rocks exposed north of the Snake River Plain in east-central Idaho are assigned to the Arco Hills, Bluebird Mountain and lower Snaky Canyon formations (ascending order). In the southern Lemhi Range, calcareous algae and associated microproblematica from these rocks include representatives of at least 13 genera and genus-level taxa within the Dasycladaceae, Aoujgaliaceae, Ungdarellaceae, and incertae familiae. Local appearances of Masloviporidium delicata and Donezella lutugini are early Morrowan or younger as determined independently by studies of associated foraminifers and conodonts. Beresella polyramosa and Komia abundans are locally restricted to Atokan rocks. These findings are consistent with compiled data on worldwide stratigraphic distributions of these taxa, and suggest that certain Upper Paleozoic calcareous algae may be of limited value in biostratigraphic correlation.