Abstract

The northern Death Valley-Furnace Creek fault zone is a major northwest-trending fault system in the Death Valley region, but the magnitude of offset and its significance to extensional tectonism in the region are controversial. Stratigraphic data have provided first-order constraints on offset across the fault zone but offer limited resolution. Previous correlations of Mesozoic thrust faults across the fault zone have relied on regional stratigraphic trends to fingerprint structurally similar thrust plates. We show that a northeast-trending Mesozoic backfold within the predominantly east-directed fold and thrust belt was probably continuous from the southern Panamint Range, California, to the Belted Range, Nevada. The relative position of this antithetic structure allows uniquely compatible correlations of three Mesozoic structures between two range blocks across the northern Death Valley-Furnace Creek fault zone independent of stratigraphic arguments. The offset structures have geometric properties of size, vergence, order, and spacing that indicate a probability less than 10-4 of the Mesozoic orogen identically repeating this structural suite in two unrelated places. Reconstruction of these correlative structures indicates 68 ± 4 km N48°W ± 6°W of apparent dextral offset between the Cottonwood and Funeral Mountains, in general agreement with previous estimates based on stratigraphic observations but of substantially higher precision. This reconstruction, and the restoration of a 30-km separation between the Funeral and Grapevine Mountains indicated by offset segments of the backfold, suggest a simple pre-extensional geometry for the Mesozoic orogen in the Death Valley region consistent with observations from unextended blocks and analogous to that of the Cordilleran orogen at the latitude of Calgary, Alberta.

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