Depositional Environment of the Cambro-Ordovician Rose Run Formation in Northeastern Ohio, and Equivalent, Gatesburg Formation in Northwestern Pennsylvania

Abstract

An ideal sedimentary sequence from the Rose Run Formation consists of three facies in the following order: (1) algal laminated/stromatolite facies, (2) bioturbated dolomite facies, and (3) crossbedded sandstone facies. The algal laminated/stromatolite facies is composed of fine to very fine crystalline dolomite with laminations 2-4 cm thick. Also observed in this facies are mudcracks. The bioturbated dolomite facies is a fine to medium crystalline dolomite with an average of 10% clastic constituents such as quartz, orthoclase, microcline, and glauconite. Bioturbation in this facies ranges from slight to well with burrows 0.5-3 cm in diameter. Other structures observed include rip-up clasts, pelloids, and oncolites. The cross-bedded sandstone facies is characterized by low-angle crossbedded, fine- to coarse-grained sandstones. This sandstone has on the average 79% quartz, 12% orthoclase, 6% microcline, 1% detridal chert, and 1-2% glauconite. The heavy mineral fraction consists of tourmaline and zircon in {approximately}1% concentrations. The grains are subrounded to rounded with a size range of 0.15-0.30 mm. Sedimentary structures include rip-up clasts, current ripples, herringbone crossbedding, and herringbone imbricate rip-up clasts.