The Tripon Pass Limestone was named by Oversby (1973) for limestones exposed 1.25 miles south of Tripon Pass in Sec. 22, T. 39 N., R. 64 E., in the Windermere Hills.

Based on conodont faunas, the Tripon Pass Limestone is Early Mississippian (latest Kinderhookian) in age (Oversby, 1973). The Tripon Pass disconformably overlies the Devonian Guilmette Formation and is conformably and gradationally overlain by the Diamond Peak Formation (Oversby, 1973). It is time equivalent, but lithologically unique from, the Joana Limestone, and is also correlatable with the Webb Formation (Coats, 1985).

At the type locality in the Windermere Hills, the Tripon Pass is composed of three informal units (Oversby, 1973). The basal 550 feet are thin to medium-bedded, slabby, dark-gray argillaceous calcisiltite and calcarenite with clastic quartz grains. These limestones weather pale gray, pink and brown. Above this are 250 feet of medium to thick-bedded, slabby and blocky calcirudite with platy interbeds of calcisiltite and calcarenite. The calcirudite contains rounded to subangular limestone clasts from 5 cm to 30 cm across, with large clasts showing laminae contorted during soft sediment deformation concentrated near the base in graded beds (Oversby, 1973). Sole marks, flutes and grooves are also present in the basal beds of the calcirudite. The upper member is about 750 feet of limestone, similar to the lower member with more argillaceous interbeds and beds of quartz siltite and arenite and quartz-chert arenite, which increases near the contact with the overlying Diamond Peak Formation. Limestones in the upper member also show obvious sole markings (Oversby, 1973).

In the southern Snake Mountains, 10 miles west of the type section, lithologically similar Kinderhookian limestones have been mapped by R. Hope (Oversby, 1973). The Tripon Pass Limestone unconformably overlies the Devonian Guilmette and is conformably overlain by the Diamond Peak Formation.

The upper member of the Joana Formation in the Pequop Mountains as mapped by Thorman (1970), may represent the Tripon Pass as suggested by Coats (1985). This member is about 1,400 feet of platy, fine-grained argillaceous limestone with a Kinderhookian fauna (Thorman, 1970).

In the southern Independence Mountains at Swales Mountain, the informally named Camp Creek Sequence gradationally overlies the Roberts Mountains Formation and is correlative with the Tripon Pass Limestone (Ketner, 1970, 1975). The sequence here is composed of repeated graded cycles 1 to 5 feet thick, of quartz-rich sandy bioclastic calcarenite, and argillaceous calcisiltite and calcilutite. The basal beds of some cycles include rip up clasts of earlier formed cycles and in some cases edgewise conglomerates. Convolute lamination and cross-bedding are common in the coarser portions of the unit while the fine-grained upper portions of cycles often contain flute marks and worm trails (Ketner, 1970; Evans and Ketner, 1971).

In the northern Hot Creek Range, Potter (1976) reported exposures of pale brown to grayish-yellow weathering limestone with abundant .5 to 2 foot thick graded beds that locally contain 2 to 4 inch lime mud interclasts. These silty and bioclastic limestones contain crinoids, ostracodes, brachiopods, echinoid spine fragments, foraminifera, and conodonts (Potter, 1976). These Osagean to Kinderhookian limestone turbidites may correlate with the Camp Creek Sequence to the north.

To the north in the Dobbin Summit area of the Monitor Range, Wise (1977) also reported limestones which may correlate with the Camp Creek Sequence. This interval is represented by regularly repeated cycles of graded and non-graded, laminated, 2 to 4 foot thick beds of brown-gray, sandy lime wackestones and mudstones separated by 2 to 6 inch layers of thin-bedded, black, calcareous mudstones. Elongate and rounded clasts of 1 to 10 mm fragments of lime mudstone, wackestone, and argillite are present throughout the graded beds (Wise, 1977). Small-scale ripple marks, burrows, soft-sediment slumps, load casts, and flute markings indicate a southwest flow direction. Fossils include tentaculites, brachiopods, crinoids, bryozoans, and sponge spicules (Wise, 1977).

The Tripon Pass is about 1,500 feet thick in the Windermere Hills (Oversby, 1973), 1,200 to 1,800 feet thick in the southern Snake Mountains (Oversby, 1973), and 650 feet thick in the Swales Mountain Quadrangle where it is referred to as the Camp Creek Sequence (Evans and Ketner, 1971; Ketner, 1975). Coats (1985) has suggested that the upper 1,400 foot thick member of the Joana described in the Pequop Mountains by Thorman (1970) may be Tripon Pass Limestone. Potter (1976) measured 300 to 400 feet of Kinderhookian limestone turbidites in the northern Hot Creek Range, and Wise (1977) measured about 350 feet in the Dobbin Summit area of the Monitor Range.

The Tripon Pass Limestone and probable equivalents are exposed in the Windermere Hills, Pequop and southern Snake Mountains, the southern Independence Mountains at Swales Mountain, and in the Peko Hills area.

The Tripon Pass-Camp Creek sequence is considered a bathyal limestone turbidite deposited before emergence and erosional removal of western assemblage siliceous and volcanic rocks, yet early in the development of the Antler foreland (Ketner, 1970; Oversby, 1973). A northeast provenance is indicated for the turbidite (Ketner, 1970b) by flute casts, suggesting southeast flowing currents. The gradationally overlying Diamond Peak Formation as well as the uppermost part of the Tripon Pass in the Windermere Hills, record the first arrival of terriginous clastic material from the exposed and eroding western assemblage siliceous and volcanic rocks.

The presence of coarse-grained limestone turbidites provide an attractive possibility for a reservoir target. It is this writer’s opinion that much of what is now mapped as the upper portion of the Joana Limestone in several ranges, including the Cherry Creek Range, may well prove to be limestone turbidites similar to the Tripon Pass. If such a facies can be mapped on a regional or prospect scale, these units may indeed provide excellent reservoirs with indigenous porosity and permeability.