The Ottawan-Aged Carthage-Colton Shear Zone: An Ancient Analog for Death Valley?

Working models for poorly exposed and highly complicated structures by necessity evolve from initially simple to increasingly complex as more complete data become available. The Carthage-Colton Shear Zone in the northwestern Adirondack Mountains of upstate New York provides an excellent example of this evolutionary process. This major Ottawan-aged crustal shear zone has been described as the base of a SE-directed nappe, an extensional syn-orogenic collapse fault, a transtensional right lateral shear zone, and as a bounding shear for a core complex. Geochronological studies across the CCSZ clearly show that the zone juxtaposes terranes with differing tectonothermal histories requiring significant vertical/horizontal offsets during Ottawan time. Detailed mapping of the CCSZ elucidates a complex history of syn-deformational folding, syn-deformational intrusion of Ottawan-aged granite bodies and syn- to post-ductile shear offsets by multiple brittle and ductile faults. In addition, kinematic indicators show that the CCSZ preserves both oblique normal and thrust movements. While the nature and interpretation of this large structure has become more complicated, the evolving picture appears increasingly similar to several modern shear zones that provide potential analogs for the CCSZ. These emerging analogs provide opportunities to propose and test models that hold promise for the development of a more complete tectonic understanding of CCSZ during the Ottawan Orogeny. A comparison between the CCSZ and tectonic development of Death Valley/Owens Valley region shows some remarkable similarities that will be discussed.