The Picuris-Pecos fault--Repeatedly reactivated, from Proterozoic (?) to Neogene
Paul W. Bauer and Steven Ralser

Abstract:

The Picuris-Pecos fault is arguably the largest-displacement, strike-slip fault exposed in the state, yet its kinematic history is poorly constrained. Although if clearly displays 37 km of dextral strike-slip, the slip is determined by offset of Proterozoic-age piercing lines, and therefore only yields a net slip since 1.4 Ga The original Picuris-Pecos fault mappers concluded that major strike-slip faulting occurred in Proterozoic time and lesser dip-slip movement occurred in Pennsylvanian and Laramide time, but recent investigators have speculated that most or all a the 37 km of strike-slip separation is actually Laramide in age. We conclude that some component of pre-Pennsylvanian (Grenville age?) slip on the Picuris-Pecos fault is a reasonable interpretation based on deflection and attenuation of Proterozoic strata along the fault, geometries and kinematics of Paleozoic and Laramide fault structures, the relative Fracturing of Proterozoic versus Paleozoic strata, and the presence of other high-angle, reactivated, pre-Pennsylvanian faults. New data from faults parallel to the Picuris-Pecos fault indicate that Laramide deformation produced concurrent strike-slip and dip-slip movements, and we speculate that the Picaris-Pecos fault and adjacent sub-parallel structures represent a positive flower structure of Laramide age. Although new apatite fission-track data permit Neogene vertical movement along the southernmost Picuris-Pecos fault, cross-cutting field relationships the northern fault exposure demonstrate tilde or no post -26 Ma throw. This along-strike variation may have resulted from different amounts of Neogene extension in the southern and northern parts of the Española Basin.


Citation:

  1. Bauer, Paul W.; Ralser, Steven, 1995, The Picuris-Pecos fault--Repeatedly reactivated, from Proterozoic (?) to Neogene, in: Geology of the Santa Fe Region, Bauer, Paul W.; Kues, Barry S.; Dunbar, Nelia W.; Karlstrom, K. E.; Harrison, Bruce, New Mexico Geological Society, Guidebook, 46th Field Conference, pp. 111-115.

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