THE TRUNCATION OF WESTERN NORTH AMERICA AND ITS CORRELATION TO ACTIVE, LARGE-SCALE, STRIKE-SLIP FAULTS: NEW OBSERVATIONS FROM THE KENNEDY MEADOWS PENDANT, KERN COUNTY, CALIFORNIA

An adequate explanation for the southward translation of the Kennedy Meadows Pendant (KMP) over 350 km from its northern origin is not provided by current geologic maps or interpretations of the Sierra Nevada. This study provides additional evidence for the role of sinistral strike-slip faulting in the emplacement of the KMP, as proposed by Dunne and Suczek (1991). The metamorphic sedimentary rocks within the KMP have been characterized as deep water, eugeoclinal strata of Paleozoic age, consistent with the hypothesis that these rocks have been translated southward from matching facies to the north during an episode of “continental truncation”. A northwest-trending ductile shear zone (Kern Shear Zone) has been identified along the southwest margin of the KMP and geologists have speculated that it was a strand of the truncation fault system. However, left-lateral slip along this zone cannot by itself explain how these eugeoclinal rocks arrived at their present location. An additional left-lateral fault must be present to the northeast of the KMP to explain this southward translation. Exposed a few kilometers to the northeast of the KMP is a small “northeastern arm” (NEA) of poorly studied pendant rock. This study of the NEA demonstrates that the NEA differs from the KMP in terms of metamorphic grade, protolith, and intensity of deformation. These dissimilarities, in addition to previous work in the region by geologists for decades, support the hypothesis that there is another discontinuity to the northeast of the KMP. This structural discontinuity might be the primary fault, in a system of faults, that translated the eugeoclinal rocks of the KMP approximately 350 km southward during late Paleozoic time. We believe this fault system may have behaved as: 1) anastomosing fault splays, 2) multiple fault surfaces at considerable depths (~8-12km), and 3) coeval or non-coeval fault splays. In addition to helping explain the late Paleozoic evolution of the KMP, this fault system provides insights with the evolution of modern, large-scale, strike-slip faults.