Mobily

Prospect, Active

Commodities and mineralogy

Main commodities Ag; As; Au; Cu; Pb; Sb; Zn
Ore minerals arsenopyrite; chalcopyrite; galena; gold; pyrite; sphalerite; stibnite
Gangue minerals carbonates; quartz

Geographic location

Quadrangle map, 1:250,000-scale TC
Quadrangle map, 1:63,360-scale B-6
Latitude 63.2693
Longitude -143.8125
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Mobily prospect is about 2.5 miles north-northeast of the junction of the Tok River and Stibnite Creek. It is at an elevation of about 4,300 feet, about 0.5 mile east-northeast of the center of section 11, T. 17 N., R. 8 E., of the Copper River Meridian. The location is accurate.

Geologic setting

Geologic description

The Mobily prospect prospect is one of several similar deposits in a mineral belt about 4 miles long that is called the Tushtena project by the current (2010) operator, Triton Gold Ltd. (Newkirk and others, 1986; DiMarchi and others, 1987; Fonseca, 2009. Work along the belt began in 1976 when Resource Associates of Alaska began geochemical sampling in the area. They soon staked claims over the Discovery Zone prospect (TC034) what then was considered massive-sulfide mineralization. Their work continued through 1987 in conjunction with several partners and consisted of geologic mapping, rock and soil sampling, and geophysical surveys along what became a belt of deposits. They drilled 17 holes along the belt in 1986 and 8 holes in 1987, totaling 3,390 meters. From 1998 to 2001, Inmet Mining Corporation and Pacific Northwest Resources Company did addition mapping, and rock and soil surveys; They drilled 8 more diamond drill holes totaling 1,489 meters. None of the holes were at the Mobily prospect. The property was idle until 2007 when James DeMarchi staked 40 claims over the belt and transferred them to Tushtena Resources Ltd. In 2008, they entered into a joint agreement with Triton Gold.
The rocks along the belt consist of two main units: the Devonian to Precambrian, Macomb Belt unit to the east and the Devonian Tushtena Pass unit to the west. They are separated by the Itra Fault, a regional scale, shallowly to moderately dipping thrust fault (Newkirk and others, 1986; DiMarchi and others, 1987; Fonseca, 2009). The Macomb Belt rocks consist mainly of felsic metatuff and volcaniclastic rocks, and sericite-carbonate-quartz phyllonite. The Tushtena Pass unit consists of schist and phyllite, metadiorite, and lithic tuff.
There are two main styles of mineralization along the belt: 1) hanging-wall, bonanza-style vein systems; and 2) footwall, sulfide stockwork and breccia vein systems. The hanging-wall, vein-type mineralization has an arsenic-lead-zinc association with narrow or no alteration envelopes and is characterized by quartz-carbonate-sulfide-gold-mica veins. The footwall, stockwork-breccia zones have a gold-rich core and peripheral antimony-rich mineralization. The deposits are correlative with others along the Tintina gold belt; the key characteristics are the low angle faults that trap the mineralization and the carbonaceous rocks that provide the right chemistry for deposition.
The rocks at the Mobily prospect are gneiss of the Macomb Belt (Newkirk and others, 1986; DiMarchi and others, 1987; Fonseca, 2009). The mineralization consists of northeast-trending arsenopyrite-quartz stockworks, veins, and breccia that cut silicified gneiss. The rocks show a strong east to west alteration zonation from Fe-carbonate alteration in the east, a central zone of sericite-ankerite+/-quartz+/-pyrite alteration, and a high silica outer zones with clay in the west. Grab and chip samples of stringer veins contained up to 920 parts per billion gold.
Geologic map unit (-143.814743784032, 63.2689325976944)
Mineral deposit model Tintina Belt-style, gold-arsenopyrite-quartz vein.
Age of mineralization About 70 to 105 Ma by analogy, if Tintina Belt-style mineralization.
Alteration of deposit The rocks show a strong east to west alteration zonation from Fe-carbonate alteration in the east, to a central zone of sericite-ankerite+/-quartz+/-pyrite alteration, to high silica zones with clay in the west.

Production and reserves

Workings or exploration The Mobily prospect prospect is one of several similar deposits in a mineral belt about 4 miles long that is called the Tushtena project by the current (2010) operator, Triton Gold Ltd. (Newkirk and others, 1986; DiMarchi and others, 1987; Fonseca, 2009. Work along the belt began in 1976 when Resource Associates of Alaska began geochemical sampling in the area. They soon staked claims over the Discovery Zone prospect (TC034) what then was considered massive-sulfide mineralization. Their work continued through 1987 in conjunction with several partners and consisted of geologic mapping, rock and soil sampling, and geophysical surveys along what became a belt of deposits. They drilled 17 holes along the belt in 1986 and 8 holes in 1987, totaling 3,390 meters. From 1998 to 2001, Inmet Mining Corporation and Pacific Northwest Resources Company did addition mapping, and rock and soil surveys; They drilled 8 more diamond drill holes totaling 1,489 meters. The property was idle until 2007 when James DeMarchi staked 40 claims over the belt and transferred them to Tushtena Resources Ltd. In 2008, they entered into a joint agreement with Triton Gold. There has been no drilling on the Mobily prospect and the work has only been geologic mapping, geophysical and geochemical surveys, and surface sampling.
Indication of production None
Reserve estimates None.
Production notes None.

References

References

1986 Annual Report - Volume 1. Resource Associates of Alaska Inc. Internal Report, 141 p
DiMarchi, J.J., Oreskes, N., Newkirk, S.R. and Hanneman, N.L., 1987. AR/TRIO 1987 Annual Report.
Fonseca, Anna, 2009, Technical report on the Tushtena gold property, Delta Mineral District, Alaska: Technical Report for Triton Gold Limited, 67 p. (as of Feb 1, 2010, posted on the Internet at: http://www.tritongold.com.au/docs/Alaskan_Project_Independent_Geologists_Report.pdf).
Newkirk, S. R., Muntzert, J. K., Puchner, C. C., Hanneman, N. L., and Flanders, R. W., 1986, AR JV
Resource Associates of Alaska Inc. Internal Report, 111 p.
Reporters D.J. Grybeck (Contractor, U.S. Geological Survey)
Last report date 4/2/2010