Anomalous Base and Precious Metals at Oil-Water Contact in #1 Teague Well, Smackover Formation, Southwest Arkansas: ABSTRACT

Abstract

A core sample containing visible sulfide concentrations in an ooid grainstone unit of the Smackover Formation was collected from 8373 ft in the 1 Teague well, outpost McKamie field, Lafayette County, Arkansas. The sulfides are concentrated beneath a well-developed, high-amplitude stylolite that appears to have acted as a permeability barrier limiting sulfide development in the upper carbonate. Examination of the electric and descriptive log information for the interval revealed that: (1) the top of the sulfide zone corresponds to the existing oil-water contact, (2) scattered sulfides occur over an 84-ft interval beginning at 8373 ft, (3) an interval of greater than 10% porosity roughly coincides with the sulfide interval, and (4) an interval of hydrogen sulfide begins about 30 ft below the top of the sulfide interval and extends well below the last described sulfides. Assay results from a 1-ft composite sample showed that the core contains 36% zinc, 12% lead, and 888 ppm silver. The silver value equals about 26 oz/ton which is a high-grade ore in a mineable setting. The Zn/(Zn + Pb) ratio of 0.75 is typical of Gulf Coast salt dome hosted mineralization with ratios of 0.68 to 0.90. The Fe/(Fe + Zn) ratio on themore » other hand is 0.02 which is far below the 0.87 to 0.97 range of salt dome hosted sulfides. Petrographic examination indicates complex replacement and pore-filling mineralization. Minerals forming the late-stage mineralization assemblage include fine-grained replacement sphalerite-galena-acanthite-chalcopyrite-pyrite/marcasite-dolomite-coarse-grained sphalerite-calcite.« less