Thin section photomicrograph (plane-polarized light) of calcite (stained pink with Alizarin Red S)
after an evaporite nodule in the Yates Fm.. Evaporites were completely leached, oil (brown) entered
secondary pores, and calcite precipitated in contact with oil (note curve meniscus surfaces on
crystals). This calcite precipitation is considered to have occurred during late-stage uplift.
Sample is from far back-reef facies of Yates Fm. in outcrops along an ephemeral
stream bank just north of Dark Canyon road, approximately 10 km west of
canyon mouth, Eddy Co., New Mexico. Long axis of photo = 2.4 mm.

© Peter A. Scholle, 1999

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