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Florida Canyon is a large, disseminated epithermal Au-Ag deposit localized along and in the footwall of the similar to N-S range-bounding fault zone on the western margin of the Humboldt Range in north-central Nevada. Mineralization was primarily controlled by range-front faults, a NE-trending shear zone and subsidiary structures. Vein and alteration mineralogy at Florida Canyon suggest an affinity with low-sulfidation epithermal deposits. However, it is hosted by weakly metamorphosed siliciclastic sedimentary rocks of Triassic age and apparently lacks igneous rocks that are coeval with mineralization. Valley-fill sediments adjacent to the deposit host the shallow portion of the Humboldt House geothermal system, which has a reservoir temperature of 219-252 degrees C and is associated with auriferous quartz veins, sinter and travertine.

Adularia in quartz-adularia-sulfide +/- gold veins at Florida Canyon yield Ar-40/Ar-39 dates of 5.14 +/- 0.14 and 4.64 +/- 0.24 Ma. Veins of this stage are consistently crosscut by colloform banded pyrite+marcasite +/- quartz veins that are locally enriched in Au, Ag, As, Hg, and Se. Stockwork zones of both the quartz- and sulfide-dominant veins are associated with silicification that grades outward through an extensive zone of kaolinite-illite-pyrite to peripheral zones of illite-chlorite-pyrite and montmorillonite +/- chlorite alteration. These assemblages were overprinted at shallow depths by steam-heated alteration consisting of alunite-kaolinite +/- sulfur cinnabar that occurs as white, powdery to friable masses along faults and quartz veins and as replacement zones in the upper part of the deposit. Viable 40Ar/39Ar dates for steam-heated alunite are 2.24 +/- 0.06, 2.08 +/- 0.14 and 1.84 +/- 0.18 Ma. The oxidation of pyritic rocks during this event and subsequent weathering generated a pervasive hematite-goethite cap to the deposit. Porcelaneous K-Na alunite that formed during weathering yielded a plateau date of 0.87 +/- 0.23 Ma and an isochron date of 0.36 +/- 0.07 Ma.

The ages and geologic data for Florida Canyon deposit are consistent with its classification as a young (< 7 Ma) amagmatic epithermal Au-Ag deposit. Assuming significant fluid flow was related to periods of major displacement on the range front fault, then faulting was particularly active at similar to 4.8 +/- 0.5 Ma, similar to 2.0 +/- 0.3 Ma and younger periods, ultimately offsetting the deposit and basin fill gravels that are < 2.6 Ma in age. Uplift of the deposit and a change to a more arid paleoclimate around 2.5 to 2.0 Ma produced a drop in the water table and the overprinting of mineralized rock by steam-heated alteration. A steam-heated lithocap was also generated at the Hycroft amagmatic deposit during this time interval, suggesting a paleoclimate or regional tectonic control on this process. By similar to 0.9 to 0.4 Ma the Florida Canyon deposit was undergoing weathering and the focus of faulting and hydrothermal activity had shifted westward to the current site of the Humboldt House geothermal system. Thus, the Florida Canyon deposit and Humboldt House field likely are manifestations of a hydrothermal system that has been episodically active for similar to 5 Ma and precipitated in excess of 7.6 Moz of gold.