AMARGOSA CHAOS: A PRODUCT OF MULTIPHASE DEFORMATION

Wright and Troxel 1984 illuminated the meaning of “Chaos” as Noble (1941) may have intended. Particularly, they show the Virgin Spring phase in great detail with innumerable faults in what appears to be a chaotic arrangement. This depiction, however, makes cross-cutting relationships difficult to derive, which led to the false-interpretation that the Virgin Spring phase formed contemporaneously in the hanging wall of a major detachment fault. A review of the literature shows the varying interpretations proclaimed from these exposures and demonstrates the influence that extra-regional paradigm shifts have had on interpretation. This study shows the formation of the Chaos was not synchronous throughout and that any models using the Amargosa Chaos as an example should be re-evaluated to include these results.

Our map of the section spanning from Rhodes Wash to Ashford Mill focuses on cross-cutting relationships. The area provides a review of textbook-like features: from intrusions to flows, faults and folds, sediments young and old, hydrothermal alteration, mass movements, and mining activity-- all together resulting in the chaotic nature. One set of major structures (D2) seem to be most responsible for the “whale shaped lozenges” and “scooped shape faults” observed by earlier mappers, upon which several other phases of deformation have been superimposed. These structures are presently low-angle and folded, but measurements suggest these faults collectively accommodate 4-5 km of slip and are best described as extensional nappes.

Mathematicians emphasize, in Chaos Theory, that small differences in initial conditions within a dynamical system may lead to deterministic chaos. While the Jubilee and Calico Chaos formations described by Noble have no such relationship, the cross-cutting relationships here reveal this ironic relationship. In other words, the modern “chaotic” appearance of the geology is the result of sequential multiphase deformation which has regional implications for distributed-faulting between the Kingston and Panamint Mountains.

Our mapping is surely not the final word on the Chaos, but is yet another phase in its understanding. We are grateful to the work of Lauren Wright and Bennie Troxel--and Levi Noble before them--for setting us on this path.