Conglomerate, limestone, and quartz sandstone

The Boyer Ranch Formation in the Clan Alpine and Stillwater Ranges in Pershing and Churchill Counties consists of a basal conglomerate overlain by partly silicified limestone that is overlain by quartz sandstone. In places it rests unconformably over Upper Triassic or younger rocks (Speed and Jones, 1969) of the Jungo terrane (JO), constraining its maximum age, and elsewhere it is faulted over Late Triassic and Early Jurassic rocks (Speed and Jones, 1969). The occurrence of conglomerate-bearing clasts of underlying units at the base of the formation supports the interpretation of unconformable basal contacts even though the unit is strongly folded (Speed and Jones, 1969). It is overlain by volcanic rocks that are comagmatic with the adjacent Middle Jurassic gabbro. In the Pamlico-Lodi (WPL) and Luning-Berlin (WLB) assemblages of the Walker Lake terrane and the Gold Range assemblage (JTRgor), a coarse clastic and shallow marine unit of Jurassic age has been mapped as the Dunlap Formation (Stewart and Carlson, 1978). It lies unconformably over both Permian and Triassic rocks (Oldow, 1981), and disconformably over other Triassic and Lower Jurassic rocks (Oldow and Bartel, 1987). Some of the rocks mapped as Dunlap likely belong in unit Jcg, however, it is not consistently defined on the Nye, Mineral, and Esmeralda County maps, and in many places rocks originally mapped as Dunlap have turned out to be a variety of other units. The Dunlap Formation therefore has not been separated from the other Mesozoic rocks on this map at this time, but it may belong with a more regional Jcg unit that defines an important mid-Mesozoic tectonic constraint.
State Nevada
Name Conglomerate, limestone, and quartz sandstone
Geologic age Middle and Lower Jurassic
Lithologic constituents
Sedimentary > Clastic > Conglomerate (Bed)
Sedimentary > Clastic > Sandstone (Bed)quartz sandstone
Sedimentary > Carbonate > Limestone (Bed)partly silicified limestone
NGMDB product
Counties Churchill - Pershing