By Philip H. Heckel
Originally published in 1975 as Kansas Geological Survey Bulletin 210. This is, in general, the original text as published. The information has not been updated.
All five members of the Stanton Formation extend southward across east-central Kansas into northern Montgomery County, where the three limestone members are developed as phylloid-algal mound complexes. South of the Elk River Valley, the Stanton Formation grades from predominantly limestone to predominantly terrigenous detrital rocks, as the mound complexes thin and disappear, and the two intervening shale members thicken substantially. The Stoner Limestone Member in the middle pinches out into shale just south of the Elk River, the Captain Creek Limestone Member at the base is traced definitely about 8 miles farther south, and the South Bend Limestone Member at the top is traced 18 miles southward to the Oklahoma border. The Eudora and Rock Lake Shale Members are defined as far south as the southernmost intervening limestone bed (Bolton) is traced; southward, a Eudora-Rock Lake interval is defined between the basal bed (Tyro) below and the South Bend Member above. Within the Stanton, south of the disappearance of the Stoner Member, three distinctive newly named limestone beds and one quartz siltstone bed lie at different stratigraphic horizons, none definitely equivalent to the Stoner Member. They are, from north to south, 1) the Timber Hill siltstone bed, 2) the Rutland limestone bed, an algal-invertebrate calcarenite, 3) the Bolton limestone bed, an invertebrate calcarenite, and 4) the Tyro oolite bed. The Timber Hill, Rutland, and Bolton beds arbitrarily separate the Eudora and Rock Lake Members; the Tyro bed marks the base of the Stanton south of the disappearance of definite Captain Creek, to which it is probably equivalent. Substantial thicknesses of quartz sandstone dominate the Rock Lake Member and the Eudora-Rock Lake interval where they constitute most of the Stanton Formation in southern Montgomery County.
The South Bend Member and Tyro oolite bed have been traced across the state border into Washington County, Oklahoma, where both had been mapped as Birch Creek Limestone by Oakes (1940a); probably only the South Bend is correlative with type Birch Creek, and the post-"Birch Creek" (= post-Tyro) detrital beds of northeastern Washington County belong to the Eudora-Rock Lake interval within the Stanton. The stratigraphy of this region seems best delineated by including the Birch Creek Limestone and Torpedo Sandstone as members of the Wann Formation, which then can be recognized as the Oklahoma equivalent of the Lane through the Stanton Formations in Kansas. In addition, the Tyro bed divides the Wann into upper and lower portions in the Kansas-Oklahoma border region.
Algal-mound complexes characterizing all three limestone members in northern Montgomery County represent a broad carbonate shoal where proliferation of calcareous algae produced enough sediment to compensate for subsidence and maintain very shallow water depths. Southward, the terrigenous detrital regime included a marine environment in which the turbid mud influx restricted the biota somewhat in the Eudora; this was succeeded by quartz sand influx in nearshore, shoreline, and probably deltaic environments of the Rock Lake. Carbonate environments that periodically became established within this dominantly detrital regime included 1) agitated open shoals where the Captain Creek and Tyro oolites formed, 2) organism-rich shoals to open lagoons where the Rutland and Bolton beds were deposited, 3) quiet open lagoons where sponge-rich calcilutite formed in the upper Captain Creek and top of the South Bend, and 4) shoreline complexes where stromatolites and oolitic to shelly quartz sandstones, locally with shale pebbles, formed at certain horizons in the Rock Lake. Following regressive sand deposition in the Rock Lake, a transgression of the sea is recorded in the fossiliferous, polymictic conglomeratic, coarse quartz sandstone that marks the base of the South Bend throughout this region.
Kansas Geological Survey, Geology
Placed on web Jan. 20, 2009; originally published May 1975.
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