Aptian-Albian extensional faulting and subsequent Laramide inversion, central Peloncillo Mountains, southwestern NM
German Bayona and Timothy F. Lawton
In southern New Mexico and Arizona, sedimentation patterns of Cretaceous and Paleogene deposits have been related to normal faulting and subsequent reverse faulting on the same structures, but specific inversion faults have not been identified. In the central Peloncillo Mountains, dramatic thickness changes in the Lower Cretaceous Bisbee Group and the Upper Cretaceous–middle Paleogene Bobcat Hill Formation between blocks bounded by high-angle, northwest-striking reverse faults suggest local control on deposition. Stratigraphic correlations of those deposits between blocks document at least three episodes of fault activity. The first episode of normal faulting in late Aptian–middle Albian time is recorded by fan-delta deposits restricted to the hanging-wall block and strata! thickening toward the hanging-wall block of the three lower formations of the Bisbee Group. The second episode of fault activity is documented by abrupt thickening on the hanging-wall block of the upper unit of the Bisbee Group. The third episode of fault activity, reverse movement along former normal faults, is recorded by elastic and tuffaceous deposits of the Upper Cretaceous?–Eocene Bobcat Hill Formation, which are restricted to the footwall block.
- Bayona, German; Lawton, Timothy F., 2000, Aptian-Albian extensional faulting and subsequent Laramide inversion, central Peloncillo Mountains, southwestern NM, in: Southwest passage. A trip through the Phanerozoic, Lawton, Timothy F.; McMillan, Nancy J.; McLemore, Virginia T., New Mexico Geological Society, Guidebook, 51st Field Conference, pp. 85-94.