The Permian basin of Texas and New Mexico is primarily a depositional feature. It occupies the site of a structural depression in the relatively stable continental interior of North America. All tectonic events that created the Permian basin and its internal elements took place during the Paleozoic.

The Central Basin platform is the most prominent tectonic element within the basin. Smaller uplifts associated with the Central Basin platform cluster on and around it. They include most of the oil-and gas-producing anticlines of this prolific province.

The Central Basin platform and many of its satellite anticlines are bounded by faults along their steeper flanks. Some of the faults are "normal," where categorized by the absence of expected strata in a well bore; others are categorized as "reverse" where a stratigraphic section is repeated in a boring. All known faults in the province are vertical or nearly so. There is no evidence of low-angle thrust faults north of the Ouachita-Marathon tectonic belt. There is no evidence that vertical movements on the faults were caused by lateral compressive forces of regional scope.

Evidence of strike-slip movement is inconclusive

End_Page 195------------------------------

because it is difficult to detect and document. The presence of a cover of Mesozoic and Cenozoic strata in much of the Permian basin obscures many of the diagnostic phenomena that might otherwise be evident. Observations in other parts of the stable interior of the North American continent suggest that transcurrent movement probably occurred along some, if not many, of the faults in the Permian basin. Such movements presumably should be looked for especially in proximity to the Ouachita-Marathon belt where the tectonic patterns indicate the influence of strong compressive stresses.

The geometry of faulted anticlines in the Permian basin, and their similarity to mapped structures in outcrop areas where underlying concordant Precambrian basement structures can be observed, suggest strongly that they originated from stresses that were directed vertically upward in the basement complex. The folding in overlying strata, therefore, is related directly to basement faulting. No lateral compressive stresses can have created anticlines that are characterized by vertical faults. The concept of folding by compressive stress, followed by normal faulting as a result of "relaxation," is not acceptable because the angles of the fault planes more closely approximate 90° than 60°. The same origin for most of the faulted anticlinal uplifts, large and small, throughout th Mid-Continent region is suggested by similarity of shapes and geologic history.

End_of_Article - Last_Page 196------------