Commodities
PrimaryGold
TertiaryAntimony, Arsenic
Commodity typeM
Deposit
Deposit typeEpithermal Vein
Model150: Epithermal vein, Comstock
Deposit sizeN
Orebody formtabular; disseminated
Ore controlOre mineralization is associated with brecciated shear zones.
Materials
Ore mineralsGold
GangueMarcasite, Pyrite, Realgar, Stibnite, Sericite, Limonite, Quartz
Geology
Host rockFelsic Volcanic Rock,Rhyolite,Porphyry,Mixed Clastic/Volcanic Rock
StructurePinyon Range Anticline and Pinyon Graben, The Pony Creek/Elliot Dome Project lies within the southern extension of the Carlin Trend, along the axis of Pinyon Range Anticline, paralleling the crest of the Pinyon Range. The Project area lies within a zone of convergence of two major structural trends which are the boundaries of a north-south series of grabens and half-grabens collectively referred to as the Pinyon Graben. Both the Pinyon Range Anticline and Pinyon Graben are estimated to be of late Mesozoic age.
Tectonic settingThe Paleozoic geology is dominated by the Antler Orogeny. Mountain building during this period resulted in the formation of a high mountain range to the west of central and eastern Nevada. Erosion of the mountains resulted in the covering of most of central and eastern Nevada with a large clastic wedge composed of conglomerate and coarse sandstone to the northwest and fine sandstone, siltstone and shale to the southeast. , In addition to the folding and low-angle faulting commonly associated with orogenic compression and mountain building, high-angle reverse fault and strike-slip faulting were widespread in response to the Antler and later orogenies in central and eastern Nevada. Important wrench fault systems were formed sometime during this period. The gold deposits found along the Carlin Trend are believed to be related to a northwest trending wrench fault that was active as early as the Jurassic era, moving at the time in a left-lateral sense. These high-angle faults are critical to localizing the fluid flow responsible for the deposition of gold deposits in central and eastern Nevada.
AlterationAlteration within the rhyolite intrusive is characterized by quartz-sericite-pyrite mineralization associated with north and north-east-trending faults. The shear zones are fragmental and/or brecciated, containing very fine-grained quartz, sericite, and pyrite or limonite. Pyrite occurs secondary in fractures. Away from the shear zones the rhyolite gradually becomes fresher, grading outward from a rock with relict feldspar ghosts to one with a distinct porphyritic texture. In the center of the intrusion the rocks have a granular texture in which the feldspars have been altered, leaving open, clay-filled vugs. ?Sanded rhyolite? and ?rhyolite sand? are terms used by Newmont to describe a unique texture of the rhyolite often occurring in mineralized areas. The sanded rhyolite consists of medium-grained rounded clasts of glassy rhyolite breccia occurring near the margins and at the base of the intrusive. Sediments along the margins of the rhyolite intrusive and immediately beneath it have been silicified, decalcified and sulfidized. In and around the mineralized cells, the sediments have been extensively oxidized (hypogene).
Economic & production
Development statusProducer
Identification
Deposit ID10310335
Alternate namesPony Creek/Elliot Dome Project, North Pony Creek
RegionNA
Data scoreB
Coordinates40.35955, -115.99609
References
LaPointe and others, 1991, NBMG Bull 106Long, K.R., DeYoung, J.H., Jr., and Ludington, S.D., 1998, Significant deposits of gold, silver, copper, lead, and zinc in the United States: U.S. Geological Survey Open-File Report 90-206A, 33 p.; 98-206B. one 3.5 inch diskette.NBMG MI-96 through NBMG MI-02Coats, NBMG Bull 101Quest International 1996 SEC Form 20-F; 1998Ruby Lake Land Status, 1978www.millcityinternational.comNBMG Pony Creek Mining District file # 74, Item 31.Amer. Mines 1996-2000http://www.standardmining.com