A thick sequence of Late Precambrian metasedimentary strata exposed in central Idaho represents part of a submarine-fan complex deposited in the Yellowjacket basin where important strata-bound cobalt deposits have been found. Three distinct sedimentary lithofacies are recognized within the Yellowjacket Formation on the basis of bedding style and sedimentary structures. These facies represent the laterally extensive and progradational sequence of basin-plain, outer-fan, and mid-fan environments.

The basal member of the sequence is a graded argillite, deposited in a basin plain as hemipelagic mud, and as very thin, graded couplets of silt and clay. This facies was succeeded by a ripped quartzite, deposited as thin layers of sand and silt in the outer-fan environment. As the top of the sequence is a laminated quartzite, deposited as beds of fine sand in a mid-fan environment by nonchannelized turbidity flows and possibly reworked by bottom currents. The vertical sequence of facies is gradational and indicates a progressive shift toward higher energy conditions with time.

A comprehensive basin analysis is not possible because adequate paleodepth and paleocurrent indicators are lacking. However, several important features of the Yellowjacket basin can be determined. Turbidite deposition was continuous and began in deep quiet water and was accompanied by the slumping and sliding of waterlogged sediment. Continued progradation had a subsiding effect on the basin. The basin was part of a passive craton margin, receiving sediment from a mountainous area in gneissic or crystalline terrane located to the east or northeast.

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