Bryantsville Breccia Bed
  

(DDC)

Ste. Genevieve Limestone,

Mississippian System


Type and reference sections: Although first used by Patton (1949, p.8), the name Bryantsville Breccia is usually attributed to Malott (1952, p. 9, 95-97), who wrote of three specific typical exposures near Bryantsville, Lawrence County, Ind.: (1) on the north side of US. Highway 50 in the NW¼NW¼ sec. 25, T. 4 N., R. 2 W., 1 mile (1.6 km) southwest of Bryantsville, and (2 and 3) in two quarries in the SW¼NW¼ and the SE¼NE¼ sec. 20, T. 4 N., R. 1 W., 1 ¼ and 2 miles (2.0 and 3.2 km) east of Bryantsville. The breccia was designated as a bed at the top of the Levias Member of the Ste. Genevieve Limestone by Gray, Jenkins, and Weidman (1960, p. 50).

Description: The breccia fragments of the Bryantsville Breccia Bed are angular to subangular consist of dense micritic limestone and partly to wholly oolitic limestone and are bound together by a matrix consisting of calcite, finely divided limestone fragments, oolitic limestone, and, less commonly, chert. The fragments range from 0.01 to 0.4 foot (0.3 to 12.2 cm) in breadth and are commonly dark gray to dark blue gray. The binding material, possibly of algal origin and in sinuous subparallel laminae, ranges in color from lighter to darker than the fragments. A zone of color-banded and wavy-laminated cherty or siliceous limestone or of noncalcarceous limestone is found in many exposures of the Bryantsville and in places is its only expression.

The breccia occurs in one or more beds and is as much as 12 feet (3.7 m) thick, although in places it is only a few inches thick. Other less persistent breccias and other lithologies similar to the Bryantsville are found in the overlying Paoli Limestone and at other horizons in the Ste. Genevieve Limestone (Perry and Smith, 1958, p. 35). These are difficult to distinguish from the Bryantsville unless enough thickness of section is available to place the breccia with respect to other identifiable stratigraphic units. A similar breccia at the top of the Ste. Genevieve of subsurface usage (see fig. 2) was noted by Zinn (1983, p. 61), who stated that "this breccia occurs stratigraphically lower than the Bryantsville because it underlies the Aux Vases Formation.

Distribution and correlation: The Bryantsville Breccia Bed marks the top of the Levias Member and the Ste. Genevieve Limestone throughout the outcrop belt in Indiana. According to Malott (1952, p. 9-10) and McFarlan and others (1955), the Bryantsville also extends into western Kentucky in the southern part of the Illinois Basin. There it is placed in the Ste. Genevieve partly on the basis of the presence of the crinoid Platycrinites penicillus (Malott, 1952, p. 9), and on the same basis it is assigned to Swann's (1963, p. 20-21) Genevievian Stage, Valmeyeran Series (Willman and others, 1975, p. 141-142).






 
 
 
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