--> ABSTRACT: Evidence for Existence of Sabkhalike Conditions in Upper Arbuckle Group, Slick Hills, Southwestern Oklahoma, by D. A. Ragland, R. N. Donovan; #90996 (1990).

Datapages, Inc.Print this page

ABSTRACT: Evidence for Existence of Sabkhalike Conditions in Upper Arbuckle Group, Slick Hills, Southwestern Oklahoma

D. A. Ragland, R. N. Donovan

In the Slick Hills of southwestern Oklahoma, the Ordovician upper Arbuckle Group carries a cryptic record of evaporite precipitation. This record is particularly well developed in the Cool Creek and, to a lesser extent, the West Spring Creek formations. Principal lines of evidence supporting this conclusion are (1) salt pseudomorphs [after gypsum(?)] preserved in chert and, less commonly, in limestone (principal pseudomorphing minerals are calcite and dolomite), (2) molds of salts in cherts, (3) traces of anhydrite and celestite within chert nodules, (4) collapse breccias we interpret as resulting from the solution of sulfate deposits, (5) dolomite beds that have appropriate isotope values, and (6) length-slow and other varieties of chert indicative of waters of high ioni strength, some of which are the distinctive "cauliflower" variety. In addition, a number of features suggest that waters of unusual composition (i.e., "modified" seawater) were present on the Arbuckle platform from time to time. These features include rare bedded [primary(?)] cherts, subaqueous shrinkage cracks, and ooids of unusual and variable textures.

Our conclusion is that during upper Arbuckle Group deposition, particularly Cool Creek deposition, the vast Arbuckle platform was periodically exposed and a sabkhalike environment developed in which dolomitization and gypsum/anhydrite precipitation took place. Subsequent reestablishment of fully marine conditions resulted in the early removal of

the sulfates, leaving only a cryptic evaporite signature.

Our interpretation can be supported in a general sense by the fact that (1) the fauna of the Cool Creek Formation is impoverished by comparison with adjacent formations, (2) the area was in a suitable climatic zone, and (3) the widespread occurrence of detrital quartz in the Cool Creek is compatible with exposure of the platform and consequent movement of clastics into the area. However, we do not wish to push the uniformitarian analogy with the modern sabkha environment too far. The enormous Arbuckle carbonate platform was an order of magnitude greater than anything existing at present, and it is unlikely that the regular shoreline paralleling and vectored facies belts seen, for example, in the Persian Gulf, could have developed on the Arbuckle platform during low-amplitude sea level fluctuations. Rather, we envisage the development of an archipelago of sabkha islands, where high points on the platform, marking sediment buildup nodes, emerged many miles from the landward margin of the craton. We have found several such islands and have been able to document their geometry in a fair degree of detail.

AAPG Search and Discovery Article #90096©1990 AAPG Southwest Section Meeting, Wichita Falls, Texas, March 11-13, 1990