Tectonics of the Chupadera Mesa region, central New Mexico
Steven M. Cather
The Chupadera Mesa region contains structures related to the Ancestral Rocky Mountain orogeny, the Laramide orogeny, late Eocene–Oligocene magmatism, and the Rio Grande rift. Major faults generally strike north, ranging from northnorthwest to north-northeast. These include (from west to east) the Hot Springs, Hubbell Springs, and Montosa faults (probable Laramide dextral-oblique reverse faults, the first two of which were reactivated as normal faults during rifting), an unnamed major arcuate normal fault and the Oscura fault, both of which separate the Neogene Trinity Basin (new name) from its footwall uplift in the Oscura Mountains, the Chupadera fault (a probable southward extension of the Picuris–Pecos strike-slip fault of northern New Mexico), and buried faults that bound the western margin of the late Paleozoic Pedernal uplift.
Large north-trending folds include the Prairie Spring anticline, the Torres syncline, the Chupadera anticline, and the Carrizozo anticline. The Prairie Spring, Chupadera, and Carrizozo anticlines owe much of their structural relief to intraformational tectonic thickening of the Yeso Formation, which caused broad arching of overlying strata. This thickening may result from contractile deformation where thrust-sense detachment faults within Permian gypsum and halite beds ramped up-section. It is possible that contractional ramps beneath these anticlines were linked kinematically to extensional, top-east detachment faults exposed east of the Socorro Basin, but this linkage has not been demonstrated. More speculatively, much of the western part of the study area may be allochthonous, with a few kilometers of top-east slip on Permian evaporite successions. Detachment faulting was polygenetic and may have been driven by: (1) gravity-driven gliding during rise of the Laramide Sierra uplift or footwall uplifts of the Rio Grande rift; (2) tectonic end-loading by crustal contraction in the Sierra uplift; or possibly (3) late Eocene–Oligocene volcanism, which (a) caused loading of allochthons by extensive volcanic fields, and (b) increased geothermal gradients that may have weakened potential detachment horizons by dewatering and volume changes during the gypsum–anhydrite transition.
Intrusion of stocks and laccoliths of the Lincoln County porphyry belt caused doming of adjacent strata, and lateral intrusion of mafic dikes into the Yeso Formation caused the development of narrow anticlines in overlying beds. These dike-related anticlines can often be traced for tens of kilometers. Dikes exposed in anticlines are typically tens of meters wide and generally do not cut strata above or below the Yeso Formation. The Oligocene Jones Camp dike may be confined to the Yeso Formation, and thus does not necessarily mark a basement fracture zone in the western part of the Capitan lineament as has been previously suggested. The Capitan lineament, which is marked by an east-trending zone of Cenozoic magmatism and late Paleozoic uplifts in eastern New Mexico and Texas, may terminate westward at the Chupadera fault.
- Cather, Steven M., 2009, Tectonics of the Chupadera Mesa region, central New Mexico, in: Geology of the Chupadera Mesa, Lueth, Virgil W.; Lucas, Spencer G.; Chamberlin, Richard M., New Mexico Geological Society, Guidebook, 60th Field Conference, pp. 127-138.