AN  INTEGRATED PETROLEUM  EVALUATION OF NORTHEASTERN  NEVADA


Introduction Evaluation Prospects


 

 

Up
 

 

 

 

 

 

 

EMIGRANT SPRINGS FORMATION

Type Section Information

The Emigrant Springs Formation was designated by Kellogg (1963) for exposures in Sec. 8, T. 9 N., R. 62 E. , in the southern Egan Range.

Geologic Age

The Emigrant Springs Formation is Late Cambrian in age. It overlies the Patterson Pass Shale and conformably underlies the Dunderberg Shale at its type locality in the southern Egan Range.

General Lithology

The Emigrant Springs Formation is composed of thin-bedded silty or oolitic limestone, and massive gray limestone and highly deformed varicolored mudstone with a basal intraformational limestone conglomerate. Fossils include echinoderm and crinoid debris, and agnostid trilobites (Kellogg, 1963).

A stratigraphically equivalent section in the northern Schell Creek Range was designated as Hamburg Dolomite by Dechert (1967) or Raiff Limestone (Young, 1960) and is here described as the Emigrant Springs Formation. The formation consists of a lower 1,100 feet of dark gray to black, fine to medium-grained, thick-bedded to massive limestone which is locally silty and dolomitic in the upper portion of the unit (Dechert, 1967). This is overlain by an upper unit of about 1,380 feet of dark gray dolomitic limestone, thin-bedded silty limestone, and oolitic limestone with rare dark chert nodules and lenses. The upper beds are commonly light blue-gray medium-grained, platy and silty limestone (Dechert, 1967).

Average Thickness

The Emigrant Springs Formation is 2,064 to 2,232 feet thick at its type locality in the southern Egan Range (Kellogg, 1963), and 2,540 feet in the northern Schell Creek Range (Dechert, 1967).

Areal Distribution

The Emigrant Springs Formation is exposed in the southern Egan Range and is present in the Schell Creek, Fairview and Bristol Ranges where it is not differentiated from other Late Cambrian units.

Depositional Setting

The presence of intraformational conglomerates, echinoid and crinoid debris, suggest that the Emigrant Springs Formation represents shallow marine shelf sedimentation.


Home Up In-Memoriam Contact
COPYRIGHT
ã 1986-2006
 
WESTERN CORDILLERA
Last modified: 09/12/06