Geology of the Alaska-Juneau lode system, Alaska

Twenhofel, William Stephens

doi:10.3133/ofr52160

Cited by 10 publications

(30 citation statements)

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“…A Triassic age has been assigned to the Perseverance Slate based on Late Triassic fossils collected by Martin (1926) and Late Triassic conodonts recovered by Gehrels et al (1992). Volcanic strata of the Gastineau Volcanic Group structurally and stratigraphically underlie the Perseverance Slate (Martin 1926;Twenhofel 1960). Permian conodonts have been recovered from carbonate lenses within the volcanic rocks (Gehrels et al 1992) resulting in the assignment of these rocks to the Gastineau Group.…”

Section: Geology Of the Mine Areamentioning

confidence: 99%

“…The AJ orebody is mostly hosted by a black phyllite unit of Triassic age (Brew and Ford 1977), named the Perseverance Slate (Martin 1926;Twenhofel 1960) (Fig. 2).…”

Section: Geology Of the Mine Areamentioning

confidence: 99%

“…Total production from the AJ mine is 102.6 t Au, 62 t Ag, 14 928 t Pb, and 14 1 t Cu. Over 9 1 Mt of ore has been milled at an average gold grade of 1.5 g/mt (Twenhofel 1960;AJ Annual Report, unpublished data, 1943). Ore bodies consist of swarms of closely grouped, gold-sulfide quartz veins that extend for over 4.5 krn alongstrike and 1050 m downdip.…”

Section: Introductionmentioning

confidence: 98%

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Structural evolution of the Alaska Juneau lode gold deposit, southeastern Alaska

Miller¹,

Barton²,

Fredericksen³

et al. 1992

Can. J. Earth Sci.

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The Alaska Juneau lode gold deposit is hosted by a series of polydeformed Permian to Late Triassic volcanic, pelitic, volcaniclastic, and mafic intrusive rocks. Rocks in the mine area have been sheared and metamorphosed to greenschist grade. Interpretation of rock fabrics indicates several generations of ductile and brittle deformation. Prior to mineralization, reverse shear occurred along northwest-striking and northeast-dipping ductile shear zones. Mineralization consists of Eocene auriferous quartz–carbonate veins, which cut the regional metamorphic fabrics. Mineralization was followed by reverse right-lateral shear along northwest-trending ductile–brittle shear zones. Two northwest-striking and steeply dipping vein sets host the bulk of the ore. Orientation of carbonate fibers within the quartz veins were used to determine the deformation regime that existed during mineralization. Plunge of the fibers indicate that down-to-the-northeast extension occurred synchronous with mineralization. Structural data support a model whereby the Alaska Juneau deposit formed after the peak of ductile deformation during a period of local extension. Localization of veins to areas of infolded phyllite and gabbro suggests that competency contrasts within host rocks enhanced vein emplacement. Veining may have been facilitated by a change from a contractional to a transpressive deformational regime which may have led to local extension and fluid migration to favorable deposition sites.

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Section: Geology Of the Mine Areamentioning

confidence: 99%

“…The AJ orebody is mostly hosted by a black phyllite unit of Triassic age (Brew and Ford 1977), named the Perseverance Slate (Martin 1926;Twenhofel 1960) (Fig. 2).…”

Section: Geology Of the Mine Areamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

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Structural evolution of the Alaska Juneau lode gold deposit, southeastern Alaska

Miller¹,

Barton²,

Fredericksen³

et al. 1992

Can. J. Earth Sci.

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“…Production from about 1893 to 1944. SOURCES : Spencer, 1906;Twenhofel, 1952;Wayland, 1960;Herreid, 1962;Goldfarb and others, 1986. …”

Section: Se3 58 18 134 21mentioning

confidence: 99%

Significant metalliferous lode deposits and placer districts of Alaska

Nokleberg¹,

Bundtzen²,

Berg³

et al. 1987

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“…Origin of gold interpreted to be from deep-crustal metamorphic fluids, or possibly a remobilized strata-bound deposit. Spencer, 1906;Twenhofel, 1952;Wayland, 1960;Herreid, 1962;Goldfarb and others, 1986Goldfarb and others, , 1988Goldfarb and others, , 1991Newberry andBrew, 1987, 1988;Light and others, 1989;Brew and others, 1991;Alaska Mineral Industry, 1993, p. 13 Kennedy and Walton, 1946;Johnson and others, 1982;Himmelberg andothers, 1987, Still, 1988;Brew and others, 1991; Significant Lode Deposits of Russian Far East, Alaska, and Canadian Cordillera sulfide Consists of sphalerite, galena, chalcopyrite, and tetrahedrite in a pyrite-rich matrix in massive pods, bands, laminations, and disseminations, associated with pyrite-carbonate-chert exhalite. Hanging wall of chlorite and sericrte sedimentary rocks.…”

Section: Cu Fesmentioning

confidence: 99%

Significant metalliferous and selected non-metalliferous lode deposits and placer districts for the Russian Far East, Alaska, and the Canadian Cordillera

Nokleberg¹,

Bundtzen²,

Dawson³

et al. 1996

Open-File Report

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This report is a written tabular compilation of the significant metalliferous and selected non-metalliferous lode deposits and placer districts of the Russian Far East, Alaska, and the Canadian Cordillera. The report provides detailed summaries of the important features of the significant lode deposits and placer districts along with a summary of mineral deposit models, and a bibliography of cited references. Data are provided for 1,079 significant lode deposits and 158 significant placer districts of the region. This version of the report is issued on standard paper

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Geology of the Alaska-Juneau lode system, Alaska

Cited by 10 publications

References 0 publications

Structural evolution of the Alaska Juneau lode gold deposit, southeastern Alaska

Structural evolution of the Alaska Juneau lode gold deposit, southeastern Alaska

Significant metalliferous lode deposits and placer districts of Alaska

Significant metalliferous and selected non-metalliferous lode deposits and placer districts for the Russian Far East, Alaska, and the Canadian Cordillera

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