WICHITA AND ANCESTRAL ROCKIES SYSTEMS AND THE TEXAS FORELAND 



243 



of subsidence, defined by the pre-Mississippian strata, the Oklahoma 

 basin, extended west-northwesterly toward the Colorado sag in central 

 Colorado. The core area of the Ouachitas received about 3000 feet of 

 sediments during this time, so the axis of the Oklahoma basin appears 

 to have lain in the northern part of the Ouachitas and under the 

 Arkansas Valley, and to have extended eastward to a connection with 

 the Appalachian geosyncline. See Plates 2, 3, and 4. 



In Late Mississippian time and during the Pennsylvanian a new 

 regimen of sedimentation dominated the region, and over the carbonates 

 and cherts great volumes of shales and sandstones were deposited. The 

 basin of sharp subsidence and accumulation followed mainly the belt of 

 later orogeny of the Ouachita system. The site of the present Ouachita 

 Mountains, the Arkansas Valley and the Wort Worth basin marked the 

 region of heavy deposition, but a spur of this arcuate basin projected off 

 to the west through the Ardmore and Anadarko basins where at least 

 10,000 feet of clastic sediments accumulated. See Plate 8 of the Early 

 Pennsylvanian. The history of Pennsylvanian sedimentation is complex 

 because of deformational impulses from time to time and place to place. 

 These will be discussed under the next heading. 



Phases of Orogeny 



Late Mississippian Phase. The great flood of Stanley, Jackfork, and 

 Johns Valley elastics in the Ouachitas and the equivalent Springer group 

 in the Ardmore basin reflect major uplift and associated deformation. 

 This was a belt in the hinterland, toward the Gulf of Mexico, most prob- 

 ably, because there is no plausible source area to the north. 



Early Pennsylvanian Phase. The first disturbance within the basin of 

 accumulation is detected in a post-Springer and pre-Dornick Hills or 

 Deese unconformity, in the Criner Hills-Ardmore basin area. See Fig. 

 15.6. This probably marked the beginning of rise of the entire Amarillo- 

 Wichita element (Swesnik and Green, 1950). See tectonic correlation 

 chart, Fig. 15.8. 



The Ardmore basin then proceeded to sink and received an addi- 

 tional 17,000 feet of sediments making up the Dornik Hills, Deese, and 

 Hoxbar groups. 



Late Pennsylvanian Phase. By McAlester time (late Lampasas), 

 the crest of the Hunton-Tishomingo uplift had been eroded to the 

 Hunton limestone, while the northeastern flank was being submerged by 

 encroaching seas. Erosion of the crest, due to intermittent uplifts, had 

 exposed the Viola limestone. Then followed a rather extensive sub- 

 mergence, and by Missouri time the entire northwest end of the Hunton- 

 Tishomingo landmass had been covered. The Ardmore basin, received 

 sediments from the Hunton-Tishomingo and Wichita land areas as well 

 as the previously elevated Ouachita Mountains. The basin spread over 

 the site of the present Arbuckle Mountains. A series of rocks was de- 

 posited in this basin that differs in fades and sequence from the material 

 that was being laid down simultaneously in the McAlester basin north- 

 east of the Hunton-Tishomingo land mass. The two basins were probably 

 never connected. 



Late in Hoxbar time, compressive forces from the southwest re- 

 juvenated the older folds of the Wichita uplift, and the entire element 

 was moved northward toward the Hunton-Tishomingo buttress. The 

 Amarillo Mountains were also rejuvenated, and the erosional detritus of 

 the "granite wash," was formed. The sediments of the Ardmore-Arbuckle 

 basin were greatly compressed, and the Arbuckle anticline originated. 

 As the forces continued to move the southern elements northward, the 

 eastern part of the Wichita system was thrust still farther north, ap- 

 parently moving as a pivot, with the west end of the Amarillo Mountains 

 remaining about stationary. The thrusting at the eastern end resulted in 

 minor folds, first in the Arbuckle anticline and later in the Hunton- 

 Tishomingo arch. Most of these minor folds became asymmetrical, and 

 many were finally overturned toward the northeast. In the final stages 

 of the movement, the major anticlines broke on their overturned axes, 

 finally developing into thrusts and overriding the adjacent synclines. 



Thirteen small erratic masses have been found toward the west 

 extension of the Mill Creek syncline (Lehman, 1945). The erratics are 

 remnants of an extensive thrust sheet which overrode at this place the 

 truncated edges of the Simpson group in post-Hoxbar and pre-Pontotoc 

 time. 



In a detailed study of a small area in the Arbuckle anticline Dun- 



