Abstract: Origin, Development, and Distribution of `Plains-Type Folds' (Compactional Features) in the Cherokee Basin of the American Midcontinent

MERRIAM, D.F and ANDREA FÖRSTER

`Plains-type folds' occur in cratonic basin environments worldwide. They are small in size, increase in definition with depth, and occur in elongated trends in the sedimentary package overlying a crystalline basement. They are important structural features because they can control the location of mineral resources. In the Cherokee Basin in southeastern Kansas, the `plains-type folds,' formed in Paleozoic sediments overlying a crystalline Precambrian basement, locally contain oil and gas. The folds were developed during the Ouachita Orogeny in the late Mississippian-early Pennsylvanian when fractured/faulted basement blocks moved differentially in response to outside stresses. Upper Pennsylvanian/Lower Permian sediments were deposited over these tilted fault blocks and differentially compacted as the overburden increased and the fault blocks continued to readjust to regional tectonic forces. The differential fault-block movement is recorded by computing a structural interval gradient for each block which can be interpreted to indicate reactivation time during the late Paleozoic. Mesozoic and Tertiary events are inferred from adjacent areas to be mainly regional tilting with reactivation locally of some `plains-type folds.' The neotectonics of the region as recorded by historical earthquakes and recent microseisms indicate adjustment is continuing, at least locally, until the present. A major uplift, the Nemaha Anticline and associated Humboldt Fault, is active today as are several major northwest-trending faults in eastern Kansas. What effect this continued movement has on the `plains-type folds' in the Cherokee Basin has yet to be determined because the basin itself seemingly is tectonically inactive at present.

AAPG Search and Discovery Article #90944©1997 AAPG Mid-Continent Section Meeting, Oklahoma City, Oklahoma