Fig. 2: Photomicrographs of representative lithologies and sulfide minerals in the upper Espanola and Serpent formations. | Communications Earth & Environment

Fig. 2: Photomicrographs of representative lithologies and sulfide minerals in the upper Espanola and Serpent formations.

From: Incomplete oxidative sulfide weathering and low atmospheric oxygen levels during the Great Oxidation Event

Fig. 2: Photomicrographs of representative lithologies and sulfide minerals in the upper Espanola and Serpent formations.

Polished sections of a laminated mudstone in the upper Espanola Formation at 860.62 m, b poorly sorted sandstone in the Serpent Formation at 795.93 m, and c granule-rich sandstone in the Serpent Formation at 762.23 m. Reflected light photomicrographs of d disseminated pyrrhotite at 860.62 m, e disseminated pyrite at 817.96 m, f subangular to rounded pyrite grains interspersed in sandstones at 795.93 m, g, h subangular to rounded pyrite grains concentrated in discrete layers at 762.23 m, and i a euhedral pyrite grain at 690.98 m. Scanning electron microscope images showing subangular to rounded pyrite grains at j, k 795.93 m, l, m 762.23 m, n, o 690.98 m. Rounded zircon and apatite grains are also shown in panels (l), (m) and (o).

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