ABSTRACT

Paleozoic sedimentary rocks in the subsurface of the Black Mesa basin of northeastern Arizona include: 0–800 feet of Cambrian dolomite, sandstone, shale, and minor limestone; 0–300 feet of Devonian dolomite and sandstone; 0–500 feet of Mississippian dolomite and limestone; 0–500 feet of Pennsylvanian redbeds and limestone; and about 2,000 feet of Permian redbeds and eolian sandstone capped by 0–400 feet of dolomite near the western edge of the basin. These rocks do not crop out, and only a few wells have penetrated them to date.

Isopach and lithofacies maps show that in all Paleozoic systems the thick marine carbonate sections of northwestern Arizona and southwestern Utah pinch out, become more clastic, or interfinger with continental sedimentary rocks southeast in the direction of the Black Mesa. At no time during the Paleozoic or Mesozoic era was the Black Mesa area a basin in the sense that it was the site of deposition of marine sediments significantly thicker than in surrounding areas. The Black Mesa structural basin was formed by differential uplift in Cenozoic time. When the Colorado Plateau was uplifted the Black Mesa rose 3,500–7,000 feet less than surrounding areas.

Possibilities for oil and gas discoveries in stratigraphic traps seem best in the northern and western parts of the Black Mesa basin, where several permeable formations appear to pinch out.

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