ABSTRACT

The De Queen Formation (Comanchean) in the main Highland Gypsum Quarry at Highland, Arkansas, consists of gypsum, limestone, and clastic sediments deposited along the landward margin of a broad, restricted, shallow lagoon. It grades downdip into the Ferry Lake Anhydrite. Gypsum as satin spar, selenite, and alabaster is abundant in the lower part of the section. Limestones ranging from lime mudstones to grainstones contain fossil mollusks, ostracods, serpulid worm tubes, and foraminifera. The gypsum and limestone lithologies are interbedded with claystones and shales.

Strontium concentration was determined on about 100 samples by X-ray fluorescence spectrometry (XRF) and was found to be controlled by diagenesis, not deposition. Strontium concentrations in the gypsum are likely controlled by the rate of recrystallization of secondary anhydrite. Levels of Sr in the limestones reflect the amount of celestite cement. The Sr content of the clastic beds correlates with the amount of Sr-rich microcrystals of strontianite, celestite, barite, and witherite.