ABSTRACT: Tectonic Mechanisms for Formation of the Central Basin Platform and Adjacent Basinal Areas, Permian Basin, Texas and New Mexico

YANG, KENN-MING, and STEVEN L. DOROBEK, Texas A&M University, College Station, TX

Formation of the Central Basin platform (CBP), with the Delaware basin to its west and the Midland basin to its east, has been attributed to the crustal deformation in the foreland area of the Marathon Orogen during the late Paleozoic. Because of complexities in the areal distribution and magnitudes of uplift along the length of the CBP, its formative mechanisms are still controversial. Previous interpretations about the mechanisms for uplift of the CBP are based on the characteristics of the boundary faults between the CBP and adjacent basinal areas. Here, an integrated tectonic model is proposed for formation of the uplift and adjacent basins based on studies of the structure of sedimentary layers overlying Precambrian basement rocks of the uplift and restoration of the lower Paleoz ic strata in the Delaware basin.

The CBP is composed of two to three segmented blocks arranged in a dextral en echelon pattern. Uplift of each block is greatest at its southwest and northeast corners. Seismic sections across the southwest and northeast corners of the Fort Stockton block are characterized by overthrust faults that dip toward the interior of the block. In contrast, normal faults at the northwest corner dip westward toward the Delaware basin. At the southwest and northeast corners, lower Paleozoic strata within the fault zone dip toward the basins at a high angle. Dip angles of these strata and the overthrust faults were used to calculate the displacement along the fault planes and the shortening of the basement. The calculated shortening of basement decreases along the boundaries away from the southwes and northeast corners; the southwest corner is more shortened than the northeast corner, suggesting that substantial differential relief developed between the southwest and northeast corners of individual blocks of the CBP during Late Pennsylvanian to Early Permian deformation.

Restored east-west profiles across the basin also reflect the nature of deformation along the western boundary of the CBP. East-west profiles are asymmetric (i.e., deeper) toward the CBP at the southwest corner of the Fort Stockton block, suggesting some lithospheric flexure due to tectonic loading by overthrusts. At the extensional northwest corner of the Fort Stockton block, the east-west profile is nearly symmetrical. East-west profiles across the shallower Midland basin and the northeast corner of the Fort Stockton block do not indicate any obvious lithospheric flexure, suggesting less shortening there.

AAPG Search and Discovery Article #91018©1992 AAPG Southwest Section Meeting, Midland, Texas, April 21-24, 1992 (2009)