The regional stratigraphy of lower Missourian rocks from eastern Kansas to central Iowa

Lamerson, Paul Richard

Publication

The regional stratigraphy of lower Missourian rocks from eastern Kansas to central Iowa

Lamerson, Paul Richard

Abstract

Recent studies of the fusulinid faunas of upper Desmoinesian and lower Missourian rocks in Iowa, Kansas, Oklahoma, and New Mexico show that many of the faunal elements formerly considered so highly characteristic of the Desmoinesian are also persistent into the Bethany Falls limestone member of the Swope formation of 'Iowa and Kansas and in rocks of similar age in Oklahoma and New Mexico. Fusulinid faunas present in the Winterset limestone of the Dennis formation and equivalent rooks from Iowa to New Mexico are comprised of rather advanced forms which would suggest a considerable time break between the Bethany Falls and Winterset limestones. These limestones are separated by the Galesburg shale formation and 'the lower members of the Dennis formation in the northern midcontinent region, and equivalent rocks are separated ·by an unconformity in the New Mexico region. On the basis of the foregoing evidence I it seemed desirable that the physical characteristics in that part of the section from Missouri to Iowa be examined. Forty- sections of rocks of the Bronson subgroup, Kansas City group, Missourian Series were investigated in an area from northern Linn County, Kansas, to northern Madison County, Iowa. Physical evidence does not indicate a break in sedimentation between the Bethany Falls limestone and the Winterset limestone. Fusulinids of the genera Oketaella, Pseudostaffellia, Millerella and Fusiella were found in the Sniabar limestone member of the Hertha formation at Section 10, Kansas City, Missouri. The Sniabar limestone becomes thinner, sandy, and oolitic in northern Missouri and Iowa. Shales of the Ladore formation were found to thicken to the north and to become sandy along the easternmost portion of the outcrop in the thesis area., No fusulinids were found in the Middle Creek limestone member of the Swope formation, which thins to the north and is locally absent in north-central Missouri. The Bethany Falls limestone is uniform and changes relatively little lithologically throughout the thesis area. The Galesburg shale formation thickens and becomes of a more calcareous nature to the north. The Canville limestone of the Dennis formation is found in only the most northerly and southerly parts of the thesis area. The Stark shale member is the most persistent member present in the thesis area.