Kinematic analysis of the southern Funeral Mountains: implications for Cenozoic extensional tectonics

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Map-view area balance of extensional strain in the west-central Basin and Range indicates that the area has undergone 250-300 km of upper crustal extension. Consistent 25-30 km moho depth across the area suggests that the ductile lower crust has uniformly thinned in response to the extension. These strain estimates are based on the palinspastic realignment of various compressional structures developed within the Late Proterozoic to Mesozoic passive margin and foreland basin rocks of the North American Cordillera. The type example of correlations used to reconstruct the west-central Basin and Range lay in Death Valley. The magnitude, order, spacing, and vergence pattern of compressional structures in the Cottonwood and Funeral Mountains indicates that the two range blocks, now separated by ~70 km along the Death Valley-Furnace Creek fault zone, were once adjoined. However, the original structural architecture in the Funeral Mountains has been aliased by extensional faulting. Thus, the correlation of the Cottonwood and Funeral Mountains is contingent on determining the true pre-extensional spacing between the compressional structures. I reconstruct one NW-SE cross section through the Funeral Mountains to determine the pre-extensional geometry of the fold-thrust belt and compare the geometry to the Cottonwood Mountains. The reconstruction indicates that the interior of the Funeral Mountains has been extended by 8 km (40%) of its pre-Miocene length. The derived pre-extensional spacing between compressional structures within the range matches that previously determined for structures in the Cottonwood Mountains. Thus, these results support reconstructions that indicate ~ 70 km across the Death Valley-Furnace Creek fault zone. Finally, the Funeral and Cottonwood Mountains are interpreted to be correlative range blocks.

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