PERMIAN STRATIGRAPHY IN THE HEAD OF LORAY WASH, NORTHEASTERN NEVADA

The head of Loray Wash, located in a Southern Pacific Railroad excavation in the southern Leach Mountains, immediately north of State Hwy 30, NE Nevada, contains a structurally deformed succession of Permian marine sedimentary rocks. A previous worker named an undesignated thickness of these rocks the Loray Fm. This was reported as the type locality for the Loray Fm - a succession of yellow-tan gypsiferous silts and thin bioclastic limestones in the head of Loray Wash, in conformable contact with the underlying Fm.

Subsequent stratigraphic correlations into this area and detailed geologic mapping show the Permian stratigraphy here as including the upper approximately 30 m of the Grandeur Fm (Leonardian) of the Park City Group, overlain by approximately 33 m of the Meade Peak Tongue of the Phosphoria Fm (Leonardian), in turn overlain nearby by the lower approximately 300 m of the Murdock Mountain Fm (Leonardian? to Guadalupian). The Loray Fm of the previous worker at this locality is considered by this author to be the Grandeur Fm.

The Grandeur Fm in Loray Wash consists of dolomitic sandstone, less calcareous sandstone and minor bioclastic limestone. Gypsiferous silts and a conformable contact with the underlying formation noted by the previous worker for the type section for the Loray Fm are absent in Loray Wash. The contact between the base of the Loray Fm, or the Grandeur Fm of this author, and the underlying formation is actually located 3.2 km to the NW. Due to discrepancies between the discription of the type section and the actual lithologies exposed there, and due to the absence of the base of the Loray Fm of the previous worker, or Grandeur Fm of this author, and also considering the stratigraphic correlations presented here, Loray Wash is considered as an inappropriate locality for the type section of the Loray Fm. Although a type section cannot be changed, future work on location and description of an appropriate typical section for the Loray Fm would be helpful for support of usage of the name by others in NE Nevada and NW Utah.