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Timing of Paleozoic-Cenozoic Tectonic Events in the Permian Basin, West Texas, From Integrated Subsidence and Structural Studies


We have generated 25 subsidence curves from widely distributed wells in the Delaware Basin, Central Basin Platform (CBP), and the Midland Basin that collectively comprise the Permian Basin of west Texas and eastern New Mexico. The subsidence curves define five separate tectonic events that controlled the patterns of sedimentation into the basin:1) Pre-collisional, passive margin phase from the Late Precambrian to Mississippian (850-355 Ma) with deposition of shallow-marine facies at average subsidence rate of 8 m/my; 2) North-south-directed, early collisional phase from the Mississippian to Early Pennsylvanian (355-323 Ma) with deposition of deep-marine shale at average subsidence rate of 6 m/my; 3) North-south-directed, main collisional phase from Early Pennsylvanian to Late Permian (323-252 Ma) with deposition of mixed, siliciclastic-carbonate deep-marine facies at average sedimentation rate of 42 m/my; 4) Post-collisional, stable platform phase from Late Permian to Late Cretaceous (252-80 Ma) with deposition of shallow-marine, carbonate facies at average sedimentation rate of 4 m/my; and 5) Laramide, east-west-directed, collisional phase from Late Cretaceous to Eocene (80-40 Ma). In the Permian basin, the post-Paleozoic sedimentary record is absent; the timing of post-Paleozoic tectonic events is inferred from adjacent areas that contain a post-Paleozoic sedimentary record. The pattern and rate of Late Paleozoic, collision-related subsidence vary across the Permian basin with the area of maximum subsidence (50-70m/my) in the south and closest to the east-west-trending thrust front of the Marathon orogenic belt supportive of a foreland flexural origin for this area of the basin. However, structural restoration of a 100-km-long, east-west regional cross-section across the CBP and western Midland Basin revealed that faults bounding the eastern edge of the structural high of the CBP originally formed as west-dipping, normal faults with a 1.3 km-thick clastic wedge deposited during the third tectonic phase listed above. We propose that the observed east-west extension of the Permian Basin occurred as the result of extensional reactivation of north-south-striking basement faults within an overall zone of north-south-directed convergence during the second and third, Paleozoic collisional phases listed above. These normal faults were inverted about 170 million years during the late Cretaceous-Eocene Laramide orogeny to form the observed west-dipping thrusts along the CBP.