Fluid flow, solution collapse, and massive dissolution at detachment faults, Mormon Mountains, Nevada

By: , and 
Edited by: Paul J. UmhoeferL. Sue Beard, and Melissa Lamb



Dissolution has removed large volumes of rock at low-angle normal faults, i.e., detachment faults, in the Mormon Mountains and the Tule Springs Hills in the eastern Basin and Range Province, southeastern Nevada. Evidence for major dissolution includes widespread solution-collapse breccias, meter-scale stylolite structures, and high-angle accommodation faults that terminate at or merge with dissolution seams. Chemically reactive fluids moving along the fault zones led to a strong depletion of 18O in the detachment fault breccias (e.g., a δ18O decrease of 8‰ relative to the unaltered rocks). These strong chemical shifts, demonstrated by (1) negative oxygen isotope values and (2) steep compositional gradients marked by metal enrichment in elements such as Au, Ag, Ti, Pb, Zn, and Cu, are generally restricted to the narrow (<1 m to 8 m) microbreccia zones.

Extensional faulting and fracturing, accompanying regional uplift, opened conduits for the influx of meteoric waters from above and hydrothermal fluids from below. As the largest, most permeable structures that formed during uplift, detachment faults focused the fluid flow. In this deformation and hydrogeologic model, dissolution-caused stratal thinning is a major complement to detachment faulting and is an important process that resolves void space issues in the reconstruction of cross section.

Study Area

Publication type Book chapter
Publication Subtype Book Chapter
Title Fluid flow, solution collapse, and massive dissolution at detachment faults, Mormon Mountains, Nevada
DOI 10.1130/2010.2463(19)
Volume 463
Year Published 2010
Language English
Publisher Geological Society of America
Contributing office(s) Geology, Minerals, Energy, and Geophysics Science Center
Description 15 p.
Larger Work Type Book
Larger Work Subtype Monograph
Larger Work Title Miocene tectonics of the Lake Mead Region, central basin and range
First page 427
Last page 441
Country United States
State Nevada
Other Geospatial Mormon Mountains
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