Page 202 - Carbonate Facies in Geologic History

Platy Algal Mounds in Basins and on Shelves 189

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o ;1
... .... ;1 <J;'
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................ r
......... .... ,. ....
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Calcarenite - filled
Channel

Fig. VI -17. General facies map of portion of Stanton Limestone outcrop in southwestern
Kansas showing algal lime mud area and lime sand filled channels and western rim of low
bank. From Heckel (1972c, Fig. 2)

as 35 km. They are characteristically filled with coated, skeletal grainstone
(Fig. VI -17).
Regional relationships are indicated on Fig.VI-18. The mounds appear to be
stacked, i.e., repeated vertically at the southern end of the outcrops along the
Kansas-Oklahoma state line. Here the section changes mainly to shale southward
into the clastic-filled Anadarko and Arkoma basins. To the east lay the low land
of the present Ozark dome. The mound accumulations probably grew westward
off the shoulder of this feature. The channels cut through the complex were also
directed westward toward the open sea shelf. An apt analogy is made by Heckel
(1972c) with modern geography along the Trucial Coast. Heckel also offers evi-
dence that the banks represent a transgressive condition followed by a still-stand
or slight regression. The mud mounds developed atop algal stromatolite heads
surrounded by oolite. They seem to represent mud banks developed in very
shallow protected marine water. Following development, a rim of bioclastic
grainstone formed at their outer, shelfward edge. The grains are abraded, indicat-