Mississippian through Permian Orogenesis in Eastern Nevada: Post-Antler, Pre-Sonoma Tectonics of the Western Cordillera
TREXLER, JAMES, University of Nevada, Reno, NV, W. SNYDER, Boise State University, Boise, ID, P. CASHMAN, University of Nevada, Reno, NV, C. SPINOZA and D. GALLEGOS, Boise State University, Boise, ID
Mississippian through Permian strata in eastern Nevada document a series of tectonic events that are either generally unrecognized, or assigned to the Antler or Sonoma orogenies. Some of these events were local and some were regional in scale; none fit either the Antler or Sonoma events as normally defined:
Antler orogeny (ends Late Devonian or earliest Mississippian)--emplacement of accretionary wedge on the passive margin;
Wendover phase (Early Mississippian)--regional uplift, erosion;
Diamond Range phase (Middle Mississippian)--folding, uplift, and erosion;
Humboldt orogeny (Pennsylvanian)--uplift, tilting and erosion;
Dry Mountain event (Late Pennsylvanian-Early Permian)--uplift, tilting and erosion, and basin segmentation;
Sonoma orogeny (Permian-Triassic)--allochthon emplacement.
Each event is documented by deformation and erosional truncation of older strata, and by clastic sequences that fill newly formed basins.
These tectonic events have mostly escaped notice until now for two reasons: (1) established cratonal stratigraphy, when applied to highly variable craton-edge sequences, tends to obscure important local perturbations, and (2) the assumption of only two Paleozoic orogenies leaves little room for more complexity, and inevitably leads to unresolvable arguments about timing and style. Little-used older terminology (e.g., "Wendover phase") is available to describe these events in some cases; refinement or abandonment of existing terminology may be necessary in others. Careful, objective stratigraphic studies will result in a more accurate, and complex, regional history.
AAPG Search and Discovery Article #91009©1991 AAPG-SEPM-SEG-SPWLA Pacific Section Annual Meeting, Bakersfield, California, March 6-8, 1991 (2009)