Mammoth

Past Producer in Shasta county in California, United States with commodities Copper, Zinc, Silver, Sulfur, Gold, Lead, Cadmium, Iron

Sections on this page

Identification information
Geographic coordinates
Site location context
Geographic areas
Public Land Survey System information
Commodities
Materials information
Alteration
Mineral occurrence model information
Host and associated rocks
Nearby scientific data
Geologic structures
Ore body information
Controls for ore emplacement
Economic information about the deposit and operations
Mining district
Land status
Ownership information
Bibliographic references
General comments
Reporter information

Geologic information

Identification information

Deposit ID	10310642
Record type	Site
Current site name	Mammoth
Alternate or previous names	Anderson, Mayflower, Sheridan, Gillespie

Comments on the site identification

Early reports of the California State Mineralogist make unclear reference to a Mammoth Mine about 6 miles to the south in the Old Diggings District. The 29th Report of the State Mineralogist contains a map of the Old Diggings District, which shows that the Mammoth Mine there is distinct from the Mammoth Mine in the West Shasta District. U.S. Smelting, Refining and Mining Company also owned patented claims in the Old Diggings District.

Geographic coordinates

Geographic coordinates:	-122.45363, 40.76113 (WGS84)
Elevation	914
Location accuracy	100(meters)
Relative position	13 miles north-northwest of Redding.

Site location context

Political divisions (FIPS codes)

Shasta(county)

California(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Bohemotash Mountain(quadrangle 1:24,000 scale)

Redding(quadrangle 1:100,000 scale)

Redding(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Sacramento Headwaters(hydrologic unit)

Upper Sacramento(hydrologic accounting unit)

Sacramento(hydrologic subregion)

California(hydrologic region)

Federal lands

Shasta-Trinity National Forest(National Forest)

National Forest FS(Type of land area)

FS(Federal land areas administered by FS)

Geographic areas

Country	State	County
United States	California	Shasta

Public Land Survey System information

Meridian	Township	Range	Section	Fraction	State
Mount Diablo	34N	005W	32	E2	California

Comments on the location information

Location point selected as adit symbol on USGS 7.5-minute quadrangle map, which represents 470-level adit (main haulage level for mine). Access route to mine not determined at this time. Quadrangle map shows unpaved road to mine.

Commodities

Commodity	Importance
Copper	Primary
Zinc Critical	Primary
Silver	Primary
Sulfur	Primary
Gold	Secondary
Lead	Secondary
Cadmium	Secondary
Iron	Tertiary

Comments on the commodity information

Commodity Info: At Mammoth Mine, the ore consisted of copper ore and zinc ore. Between 1905-1925, 3,311,145 tons of copper ore and 84,000 tons of zinc ore were mined. Lydon and O?Brien (1974) reported the copper ore averaged 3.99% Cu, 4.20% Zn, 2.24 oz/ton Ag, and 0.038 oz/ton Au. The zinc ore averaged 21.1% Zn, 2.40% Cu, 5.79 oz/ton Ag, and 0.078 oz/ton Au. Similarly, Kinkel and Hall (1952) reported the copper ore averaged 4-5% Cu, 2-3 oz/ton Ag, and 0.03-0.04 oz/ton Au. The zinc ore consisted of 27-37% Zn, 1-2% Cu, 1.4-6.5 oz/ton Ag, and 0.02-0.4 oz/ton Au.

Howe (1985) divided the mineralization into six stages, as follows:
1) Precipitation of framboidal and colloform pyrite and sphalerite;
2) Deposition of fine-grained arsenopyrite and coarse-grained pyrite; the latter encloses tiny inclusions of pyrrhotite;
3) Precipitation of chalcopyrite, sphalerite, galena, tennantite, pyrrhotite, bornite, and idaite; and replacement of stage 2 minerals;
4) Recystallization and remobilization of previous stage minerals;
5) Deposition of quartz, sericite, and calcite;
6) Supergene enrichment.
Ore Materials: Pyrite, chalcopyrite, sphalerite, galena, tetrahedrite-tenantite, arsenopyrite, bornite, idaite, digenite, bornite, covellite, chalcocite, unknown gold, unknown silver
Gangue Materials: Quartz, sericite, calcite, chlorite

Materials information

Materials	Type of material
Pyrite	Ore
Chalcopyrite	Ore
Sphalerite	Ore
Galena	Ore
Tetrahedrite	Ore
Tennantite	Ore
Arsenopyrite	Ore
Bornite	Ore
Idaite	Ore
Digenite	Ore
Bornite	Ore
Covellite	Ore
Chalcocite	Ore
Quartz	Ore
Sericite	Ore
Calcite	Ore
Chlorite	Ore

Alteration

(Local) Sericitic; quartz, sericite, pyrite, chlorite
Hematitic (gossan); hematite

Gossan and minor supergene enrichment are present locally. Oxidation is known to extend up to 150 feet in from the present erosion surface. Throughout the district, hydrothermal alteration, pervasive below the ore zone and absent above, developed a quartz-sericite-pyrite+/-chlorite assemblage (Kistler and others, 1985 and Reed, 1984).

Mineral occurrence model information

Model code	184
USGS model code	28a
Deposit model name	Massive sulfide, kuroko
Mark3 model number	93

Host and associated rocks

Host or associated

Host

Rock type

Volcanic Rock (Aphanitic)

Rock type qualifier

Rhyolite lava

Rock unit name

Balaklala Rhyolite

Stratigraphic age (youngest)	Middle Devonian
Stratigraphic age (oldest)	Early Devonian

Host or associated

Host

Rock type

Volcanic Rock (Aphanitic) > Felsic Volcanic Rock > Rhyolite

Rock type qualifier

lava

Rock unit name

Balaklala Rhyolite

Stratigraphic age (youngest)	Middle Devonian
Stratigraphic age (oldest)	Early Devonian

Host or associated

Host

Rock type

Volcanic Rock (Aphanitic) > Pyroclastic Rock > Volcanic Breccia (Agglomerate)

Rock type qualifier

rhyolite

Rock unit name

Balaklala Rhyolite

Stratigraphic age (youngest)	Middle Devonian
Stratigraphic age (oldest)	Early Devonian

Host or associated

Host

Rock type

Volcanic Rock (Aphanitic) > Pyroclastic Rock > Tuff

Rock type qualifier

rhyolite

Rock unit name

Balaklala Rhyolite

Stratigraphic age (youngest)	Middle Devonian
Stratigraphic age (oldest)	Early Devonian

Host or associated

Associated

Rock type

Plutonic Rock > Granitoid > Tonalite > Trondhjemite

Rock unit name

Mule Mountain stock

Stratigraphic age (youngest)	Early Devonian
Chronological age	400
Dating method	K-Ar

Host or associated

Associated

Rock type

Volcanic Rock (Aphanitic) > Mafic Volcanic Rock > Basalt

Rock unit name

Copley Greenstone

Stratigraphic age (youngest)	Early Devonian

Host or associated

Associated

Rock type

Volcanic Rock (Aphanitic) > Intermediate Volcanic Rock > Andesite

Rock unit name

Copley Greenstone

Stratigraphic age (youngest)	Early Devonian

Nearby scientific data

(1)	-122.45363, 40.76113	ListMap

Economic information

Geologic structures

Type of structure	Local
Structure description	California Fault, Eureka Fault, Yolo Fault, 313 Fault, 12 Drift Fault, and Gossan Fault. All are post-ore normal faults that offset the orebodies.
Type of structure	Regional
Structure description	None identified

Ore body information

General form Lens

General form	Lens

Controls for ore emplacement

Kinkel and Hall (1952) believed the ore bodies occur along the crest of a broad arch marked by steep cleavage, which is absent elsewhere. District-wide, Albers and Bain (1985) identified three main linear trends, N23?E, N37?E, and N60?E defined by faults, clusters of ore bodies and the long axes of ore bodies. Furthermore they noted that most of the large ore bodies occur at the intersections of these trends and surmised that the faults, especially at the intersections, provided conduits for emanating ore fluids. Post-mineral normal faults disrupt the lateral continuity of the ore.

The massive sulfide occurs with sharp contact within the upper unit of the Balaklala Rhyolite. The coarse phenocryst unit of the Balaklala Rhyolite consistently overlies the ore.

Comments on the geologic information

INTRODUCTION AND TECTONIC SETTING

The Mammoth Mine is one several copper-zinc mines in the eastern Klamath Mountains. The two copper-zinc districts of Shasta County are the East Shasta and West Shasta Districts. Mammoth Mine is in the West Shasta District. The Klamath Mountains geomorphic province consists of four imbricate, fault-bounded, east-dipping plates of oceanic affinity, which have been further subdivided into several terranes (Irwin, 1994; Irwin and Mankinen, 1998). Lithologies include variably metamorphosed volcanic and sedimentary rocks and ultramafic masses, intruded locally by post-amalgamation plutons. Volcanic rocks range in composition from mafic through silicic. Sedimentary rocks are chiefly pyroclastic beds, graywacke, and shales with minor cherty and calcareous layers. The plates, from west to east, are the Western Jurassic, Western Paleozoic and Jurassic, Central Metamorphic, and Eastern Klamath (Irwin, 1981). Both the West Shasta and East Shasta Districts are within the Eastern Klamath plate. On a regional scale, the terranes are progressively younger to the west. Within individual plates, however, the east-dipping stratigraphy places stratigraphically higher units east of older units. Consequently, Permian to Triassic rocks of East Shasta District rocks lie east of the Devonian rocks of the West Shasta District.

Origin of the massive sulfide ore of the West Shasta District has been the subject of geologic debate for years. The most comprehensive and recent evaluation of the deposits is found in a special issue of Economic Geology and the Bulletin of the Society of Economic Geologists, volume 80, number 8. As presented in this volume, the West Shasta Copper-Zinc district is now generally considered to represent stratabound Kuroko-type volcanogenic massive sulfide deposits. The deposits developed during the Early Devonian within a very depleted (exceedingly more depleted in light rare earth elements than in heavy rare earth elements), ensimatic island-arc regime. The arc formed a submarine volcanic pile consisting of a bimodal suite of low-potassium volcanic rocks, represented by the Copley Greenstone and the overlying Balaklala Rhyolite (Bence and Taylor, 1985). Interpretations of trace-element geochemistry of these rocks vary. Bence and Taylor (1985) infer a calc-alkaline trend, whereas Lapierre and others, (1985) infer a tholeiitic trend. Further explanation of this tectonic model is offered below.

PRINCIPLE FORMATIONS

The original fabrics and petrography of the two main rock units of the Mammoth area have been obscured by regional greenschist-facies metamorphism (probably during the Mesozoic) and hydrothermal alteration associated with mineralization. Some sedimentary structures are preserved in the pyroclastic units. Primary fabrics or structures within the massive sulfide unit are lost, however. Both units display large lateral variation in thickness and an abundance of breccia and conglomerate indicating that the depositional environment was topographically irregular.

The oldest unit, the Copley Greenstone, is a 1,800-meter thick sequence of pillow basalts, andesites, and pyroclastic flows with high-Mg andesites near the top. It underlies the Balaklala Rhyolite. The high-Mg andesites compare favorably to boninites recovered from the Marianas arc. Boninites, found in present-day arcs, represent the first stages of back-arc development. Therefore, the high-Mg andesites of the upper Copley Greenstone probably represent the development of an extensional regime and progression to silicic volcanism represented by the Balakala Rhyolite (Lapierre and others, 1985; and references therein).
The contact between the Balaklala Rhyolite and the Copley Greenstone is locally gradational; in places, rounded clasts of Balaklala-like rhyolite are found in a tuffaceous, andesitic matrix. A few thin flows of Copley-like greenstone are interlayered with the lower part of the Balaklala rhyolite suggesting that the Copley Greenstone and the Balaklala Rhyolite are roughly coeval. Additionally, Copley-like pillow basalts occur within the Balaklala Rhyolite (Albers and Bain, 1985).

The 1,000-meter thick Balaklala Rhyolite hosts the massive sulfide ores and consists of siliceous flows, conglomerates, and tuffs (Lapierre and others, 1985). Discontinuous lenses of water-laid tuff overlie nearly all the ore bodies. Some of the tuff beds are ripple-marked, and one contained a fish plate of Devonian age. The lack of intercalated sediments within the volcanic pile suggests a deeply submerged arc (Doe and others, 1985, Lapierre and others, 1985), although apparent contamination of Pb (Lapierre and others, 1985) and Sm-Nd (Kistler and others, 1985) indicates some pelagic input. The Balaklala Rhyolite and the nearby Mule Mountain trondhjemite stock are remarkably similar in petrologic and rare-earth element characteristics, and isotopic age. These similarities and corroborative field relationships imply that stock and rhyolite are probably comagmatic (Albers and Bain, 1985). The Mule Mountain stock has been dated at 400 Ma (K-Ar, hornblende and U-Pb, zircon).

The Balaklala Rhyolite is subdivided into three units. The upper unit, distinguished by the presence of dark quartz phenocrysts in excess of 4mm in diameter, consists of massive volcanic flows overlying pyroclastic material. The middle unit consists of rhyolite flows, containing quartz phenocrysts 1-4 mm in size, and a complex assortment of tuffs, breccias, and pyritic massive sulfide bodies. The sulfide ore bodies are stratabound and restricted to the upper part of the middle unit. The lowermost unit consists of non-porphyritic to slightly porphyritic tuffs and breccias (Kinkel and others, 1956).

EXTENSION AND VOLCANISM

Extension (perhaps back-arc spreading) and coeval Balaklala volcanism, resulted in a half dozen silicic eruptive centers (Kinkel, 1966; Albers and Bain, 1985), a series of NW-NE-dipping extensional faults, and abundant NE-trending rhyolitic dikes that intrude the Copley Greenstone. Lindberg (1985) postulated that the extensional faults represent graben-like structures that both localized hydrothermal activity and captured volcanic flows and sediments. Field evidence of graben formation is sparse. The proliferation of breccia and conglomerates in the volcanic units and the extreme variation in unit thickness suggests irregular topography, however. Albers and Bain (1985) identified three main linear trends, N23?E, N37?E, and N60?E defined by faults, clusters of ore bodies, and the long axes of ore bodies. Furthermore, they noted that most of the large ore bodies occur at the intersections of these trends and surmised that the faults, especially at the intersections, provided conduits for emanating ore fluids. Apparently, submarine fumaroles exhaled the ore fluids, which upon mixing with seawater precipitated sulfide minerals. During either a lull in volcanism or a brief interval of radically accelerated ore formation, sulfide precipitation dominated over volcanic sedimentation. The sulfide minerals accumulated as a conformable massive sulfide horizon within the strata of the contemporaneous Balaklala Rhyolite. Earlier interpretations of the deposits described them as a nearly thorough replacement of a highly favorable stratum of unknown original composition (Kinkel and Hall, 1952).
Kinkel and others (1956) identified two probable volcanic centers and estimated the location of several others. The best-defined center, interpreted to represent a cumulo-dome, is just west of Mammoth Mine. Its roughly oval-shaped body is about 425 meters thick and 2.5 kilometers across. It consists of a body of coarse-phenocryst rhyolite porphyry intruded as vertical dikes, lenses, and a stockwork into shattered wall rocks of non-porphyritic rhyolite. The intrusion contains xenoliths of the non-porphyritic rock. This center probably was a major source of all three units of the Balaklala Rhyolite because, adjacent to the dome, they form thick arcuate belts that contain large amounts of coarse- and fine-grained pyroclastic rocks (Albers and Bain, 1985).

The second volcanic center is submerged beneath Shasta Lake, except on the south, where it is characterized by a jumble of rhyolitic breccia. The fragment size in the breccia decreases to the south for a mile where sparse, small fragments are found in greenstone tuff (Kinkel and others, 1956). Four other probable centers have been identified, but are poorly defined (Albers and Bain, 1985).

This volcanic pile formed over oceanic lithosphere that by mid-Devonian began subducting under the North American continent. The progressive subduction of the oceanic plate lead to the arc's eventual convergence with the continent and ultimate accretion. As noted above, the younger (Pennsylvanian-Permian) arc of the East Shasta District lies east of the Devonian arc. Hutchinson and Albers (1992) suggested that the Pennsylvanian-Permian island arc formed in a back-arc basin between the continent and the Devonian arc. In this case, the younger arc would have accreted first. This implies that either prior to or after its accretion, the Permian arc was underthrusted by the Devonian arc. This suggests that stratigraphic superposition of the Permian strata is structural not depositional. Available geologic maps of this region do not show a tectonic boundary between these arcs (Fraticelli and others, 1987; Strand, 1962). Whether the two arcs accreted independently or as one package, the accretion occurred after Pennsylvanian-Permian time.

The validity of a back-arc basin model is challenged by regional biostratigraphy that suggests prohibitively large distances between the Eastern Klamath plate and North American craton in the Permian. The eastern Klamath area is crossed by a side-by-side pair of N-S trending biostratigraphic belts, defined by the unique McCloud fauna and Tethyan fauna. Both faunal assemblages are Pennsylvanian-Permian in age and distinct from contemporaneous North American fauna. The western belt is defined by the McCloud fauna, which is found in the McCloud Limestone. Stratigraphically, the McCloud Limestone occurs between the Devonian and Permian volcanic arc sequences. Tethyan fauna defines the eastern belt. These distinct faunas suggest that their host rocks are far traveled (5,000 km or more) (Stevens and others, 1990), an interpretation that is incompatible with a simple back-arc basin model. The origin of these faunal assemblages is controversial, however. Opponents to an exotic origin of these terranes suggest that the fauna developed in an offshore arc close to (within 1,000 km) but biologically isolated from North America. Similarities between Middle Ordovician to Middle Devonian faunas of the Eastern Klamath Terrane and cratonal North America suggest relative proximity (< 1,000 km) (Potter and others, 1990). Furthermore, the presence of continentally derived sediments in related formations supports that suggestion (Miller and others, 1992; and references therein).
HYDROTHERMAL SYSTEM

During deposition of the middle unit of the Balaklala Rhyolite, rifting formed submarine basins or grabens (Lindberg, 1985) concomitant with the development of a hydrothermal system. This system circulated heated (100- 425?C; Taylor and South, 1985), acidified (pH 3-5; Reed, 1984) seawater through the volcanic pile. The hydrothermal fluids leached sulfur and base metals from the surrounding rocks. The metals eventually were discharged at hot springs and precipitated on the seafloor, accumulating in the downfaulted basins. Mass balance considerations and isotopic analysis suggest that greater than 95% of the sulfur in the ore deposits could have been leached from the Copley Greenstone during hydrothermal alteration (Taylor and South 1985).

MASSIVE SULFIDE ORE

The best description of the ore throughout the district is found in Kinkel and others (1956) from which the following is derived. The massive sulfide occurs with sharp contact within the upper unit of the Balaklala Rhyolite. The coarse-phenocryst unit consistently overlies the ore. Deformation and recystallization of the ore has erased primary textures or sedimentary structures. The ore consists of a chaotic mixture of breccia, crystal aggregates, and minor crosscutting veins. The ore is generally localized along fold axes, but it also occurs along the flanks. It is most common in synformal basins, but also occurs along anitformal structures. Pre-mineral and post-mineral faults are common. Some pre-mineral faults served as feeder channels, some of which show wallrock alteration. Others show only localized mineralization within the fault plane. Post-mineral normal faults offset the orebodies from several centimeters to 90 meters (Kinkel and others, 1956).

At Mammoth Mine, the orebodies form large lenses of copper- and zinc-bearing pyrite ore within a diffuse, widespread ore zone. The ore zone is elongate NE-SW, plunges slightly to the south, and is 1,280 meters long. It crops out on the northeast in a canyon wall, where it projects into the sky. It is thickest (up to 300 meters) in the central portion. The orebodies occurred along the crest of a broad upright arch. The crest is marked by steep foliation that is absent elsewhere. The zone is moderately disrupted by a series of NE-NW dipping normal faults. Ore was mined down to 213 meters, although the workings reached 243 meters. The largest stopes observed by Kinkel and Hall (1952) measured 274 meters by 152 meters horizontally and 33.5 meters vertically (Kinkel and Hall, 1952).

At Mammoth Mine, thin (less than 3 meters) gossan formed in three locations. In other parts of the district, large and well-developed gossan formed. These were oxidized and enriched. A comparison of the production figures from one of the gossan, the Gossan Orebody, and average grades of the primary ore showed a two-fold enrichment of gold and silver. Covellite and chalcocite were reported present in the gossan (Kinkel and Hall, 1952).

Economic information about the deposit and operations

Operation type	Underground
Development status	Past Producer
Commodity type	Both
Deposit size	Medium
Significant	Yes
Discovery year	1880

Mining district

District name	West Shasta District
District name	Iron Mountain District

Land status

Ownership category	Private
Area name	Shasta County Planning Department

Ownership information

Type Owner-Operator

Owner U.S. Smelting, Refining and Mining Company

Type	Owner-Operator
Owner	U.S. Smelting, Refining and Mining Company

Comments on the workings information

Several levels of tunnels with raises and winzes amounted to at least 60,000 feet of development. Nine principle adits were driven at altitudes between 2,426 and 3,096 feet. A few short, unconnected adits were driven at altitudes up to 3,250 feet. Depth was principally gained by tunneling lower on the hillsides. Maximum vertical depth was 800 feet. The main haulage level was the 470-foot-level adit, at an elevation of 2,820 feet, driven a little north of west for about 3,500 feet. Plan view of the workings displays a dominant E-NE trend following the orebodies. Only the Gossan orebody deviates from this trend.

Comments on other economic factors

Between 1905-1925, 3,311,145 tons of copper ore and 84,000 tons of zinc ore were mined at Mammoth Mine.

Lydon and O?Brien (1974) reported the copper ore averaged 3.99% Cu, 4.20% Zn, 2.24 oz/ton Ag, and 0.038 oz/ton Au. The zinc ore averaged 21.1% Zn, 2.40% Cu, 5.79 oz/ton Ag, and 0.078 oz/ton Au. Total silver production was 7,416,965 ounces. Total zinc production was about 313,711,000 pounds, including 84,000 tons of ore mined 1914-1915 that averaged 21.10% zinc. Several thousand pounds of cadmium were recovered at the electrolytic zinc plant in Kennett.

Kinkel and Hall (1952) reported the copper ore averaged 4-5% Cu, 2-3 oz/ton Ag, and 0.03-0.04 oz/ton Au. The zinc ore consisted of 27-37% Zn, 1-2% Cu, 1.4-6.5 oz/ton Ag, and 0.02-0.4 oz/ton Au.

Comments on development

Presumably, the deposit was discovered before 1890. No significant mining had occurred prior to 1904 when U.S. Smelting, Refining and Mining Company purchased the property. Large-scale production began in 1905 and continued until 1919, when operations ceased until 1923. Operations resumed in 1923 and ultimately ceased in 1925. Between 1905-1925, 3,311,145 tons of copper ore and 84,000 tons of zinc ore were mined. Ore was transported to the smelter in Kennett. Some exploration has occurred since, but no mining.

Hassemer (1983) presented preliminary findings of a reconnaissance geochemistry study of the West Shasta District. The report evaluated various media and the effectiveness of various techniques. Water samples and stream-sediment samples (pan-concentrated and bulk) were collected. Pan concentrates were divided into three fractions (one non-magnetic and two magnetic fractions) by heavy liquid separation and electromagnetic separation. The bulk stream-sediment samples were divided into three fractions based on sieve size. Various analytical methods were employed. The results of the water analysis show that that copper and sulfate concentrations and specific conductance were useful values for reconnaissance. The coarse fraction of the stream sediments (-20 to +80 mesh) proved to be the best fraction for reconnaissance work. Lastly, the non-magnetic fraction proved to have the most intense values with the greatest contrast.

The U.S. Geological Survey also tested the use of near-infrared spectroscopy (Raines and others, 1985) and electrical geophysical exploration methods (Horton and others, 1985) in the West Shasta District. Near-infrared spectra (800-2,500 nm) proved to define gossans within the district. The gossans showed distinctive spectral characteristics of goethite (~900 nm) and diaspore (1,400-2,500 nm). Furthermore, spectral differences between gossans correlated with the size of the massive sulfide deposits. The shape and depth of conductive bodies were defined by the application of combined induction techniques. The conductive Hornet orebody was successfully detected within resistive rhyolite by each of the induction surveys employed. However, shale units and various fault zones in the vicinity are also conductive, which confounds interpretation. Differentiation of various conductors required the integrated use of several conduction methods.

Comments on the environmental information

Mammoth Mine is in the rugged headwaters area of the Sacramento River in the eastern Klamath Mountains. The area consists of an uplifted, dissected surface into which a dendritic pattern of streams is incised. Strath terraces along the Sacramento River reveal 200 feet of incision. Ridgelines in the vicinity are relatively level with consistent elevations between about 3,500-4,000 feet. It is thought that these ridges represent monadnocks. Some streams are perennial, although the smallest tributaries are dry in the summer and early fall. Precipitation is seasonal, with most of it occurring during the winter. Stream downcutting and headward erosion cause the mass wasting of oversteepened and undercut slopes. This has resulted in steep V-shaped canyons mantled with slide material. Land use, such as mining and the clearing of timber for use in the mines and smelters, accelerated the rate of erosion in the district. Steep, deep gullies are prevalent. The main vegetation in the vicinity is a mix of pine and oak at lower elevations, with pine dominant at higher elevations. At the deposit, vegetation is a sparse mixture of conifer and scrub brush. The presence of sulfides in the rock has caused widespread discoloration of the rock.

Reference information

Bibliographic references

Deposit

Albers, J.P. and Bain, J.H.C., 1985, Regional setting and new information on some critical geologic features of the West Shasta District, California: Economic Geology, v. 80, p. 2072-2091.
Deposit

Averill, C.V., 1939, Mineral resources of Shasta County: California Journal of Mines and Geology, v. 35, no. 2, p. 108-191.
Deposit

Bence, A.E. and Taylor, B.E., 1985, Rare earth element systematics of West Shasta metavolcanics rocks: petrogenesis and hydrothermal alteration: Economic Geology, v. 80, p. 2164-2176.
Deposit

Brown, G.C., 1915, The counties of Shasta, Siskiyou, Trinity: California State Mining Bureau 14th Report of the State Mineralogist, p. 767-769.
Deposit

Doe, B.R. and others, 1985, The plumbotectonics of the West Shasta Mining District, California: Economic Geology, v. 80, p. 2136-2148.
Deposit

Fraticelli, L.A. and others, 1987, Geologic map of the Redding 1 x 2 degree quadrangle: Shasta, Tehama, Humboldt, and Trinity counties, California: U.S. Geological Survey Open-File Report 87-257, scale 1:250,000.
Deposit

Guilbert, J.M. and Park, C.F., Jr., 1986, The geology of ore deposits: W.H. Freeman and Company, New York, p. 589-595.
Deposit

Hassemer, J.R., 1983, Some preliminary findings of a reconnaissance geochemistry study, West Shasta District, California: U.S. Geological Survey Open-File Report 83-57, 16 p.
Deposit

Horton, R.J. and others, 1985, Electrical geophysical investigations of massive sulfide deposits and their host rocks, West Shasta Copper-Zinc District: Economic Geology, v. 80, p. 2213-2229.
Deposit

Howe, S.S., 1985, Mineralogy, textures, and relative age relationships of massive sulfide ore in the West Shasta District, California: Economic Geology, v. 80, p 2114-2127.
Deposit

Huston, D.L., and others, 1996, Productivity of volcanic-hosted massive sulfide districts: New constraints from the d18O of quartz phenocrysts in cogenetic felsic rocks: Geology, v. 24, P. 459-462.
Deposit

Hutchinson, R.W. and Albers, J.P., 1992, Metallogenic evolution of the Cordilleran region of the western United States, in Burchfiel, B.C. and others, editors, The Cordilleran Orogen: Conterminous U.S.: Geological Society of America, The Geology of North America, v. G-3. p. 629-652.
Deposit

Irwin, W.P., 1981, Tectonic accretion of the Klamath Mountains, in Ernst, W.G., editor, The geotectonic development of California: Prentice-Hall, Englewood Cliffs, New Jersey, p. 29-49.
Deposit

Irwin, W.P., 1994, Geologic map of the Klamath Mountains, California and Oregon: U.S. Geological Survey MIS Map I-2148, scale 1:500,000.
Deposit

Irwin, W.P. and Mankinen, E.A., 1998, Rotational and accretionary evolution of the Klamath Mountains, California and Oregon, from Devonian to present time: U.S. Geological Survey Open-File Report 98-114.
Deposit

Jenkins, O.P., 1948, Copper in California: California Division of Mines Bulletin 144, p. 334.
Deposit

Kinkel, A.R., Jr. and Hall, W.E., 1952, Geology of the Mammoth Mine, Shasta County, California: California Division of Mines Special Report 28, 16 p.
Deposit

Kinkel, A.R., Jr. and others, 1956, Geology and base-metal deposits of West Shasta Copper-Zinc District, Shasta County, California: U.S. Geological Survey Professional Paper 285, 156 p.
Deposit

Kinkel, A.R. and Kinkel, A.R., Jr., 1966, Copper, in Albers, J.P., editor, Mineral resources of California: California Division of Mines and Geology Bulletin 191, p.141-150.
Deposit

Kistler, R.W. and others, 1985, A reconnaissance Rb-Sr, Sm-Nb, U-Pb, and K-Ar study of some host rocks and ore minerals in the West Shasta Cu-Zn District, California: Economic Geology, v. 80, p. 2128-2135.
Deposit

Lapierre, H. and others, 1985, Geodynamic setting of early Devonian Kuroko-type sulfide deposits in the eastern Klamath Mountains (Northern California) inferred by the petrological and geochemical characteristics of the associated island-arc volcanic rocks: Economic Geology, v. 80, p. 2100-2113.
Deposit

Lindberg, P.A., 1985, A volcanogenic interpretation for massive sulfide origin, West Shasta District, California: Economic Geology, v. 80, p. 2240-2254.
Deposit

Lydon, P.A. and O?Brien, J.C., 1974, Mines and mineral resources of Shasta County, California: California Division of Mines and Geology County Report 6, 154 p.
Deposit

Miller, E.L. and others, 1992, Late Paleozoic paleogeographic and tectonic evolution of the western U.S. Cordillera, in Burchfiel, B.C. and others, editors, The Cordilleran Orogen: Conterminous U.S.: Geological Society of America, The Geology of North America, v. G-3. p. 57-106.
Deposit

O?Brien, J.C., 1957, Copper, in Wright, L.A., editor, Mineral commodities of California: California Division of Mines Bulletin 176, p.169-182.
Deposit

Poole, F.G. and others, 1992, Latest Precambrian to latest Devonian time; Development of a continental margin, in Burchfiel, B.C. and others, editors, The Cordilleran Orogen: Conterminous U.S.: Geological Society of America, The Geology of North America, v. G-3. p. 9-56.
Deposit

Potter, A.W. and others, 1990, Early Paleozoic stratigraphic, paleogeographic, and biogeographic relations of the eastern Klamath belt, northern California, in Harwood, D.S. and Miller, M.M., editors, Paleozoic and early Mesozoic paleogeographic relations; Sierra Nevada, Klamath Mountains, and related terranes: Geological Society of America Special Paper 255, p. 57-74.
Deposit

Raines, G.L. and others, 1985, Near-infrared spectra of West Shasta gossans compared with true and false gossans from Australia and Saudi Arabia: Economic Geology, v. 80, p. 2230-2239.
Deposit

Reed, M.H., 1984, Geology, wall-rock alteration, and massive sulfide mineralization in a portion of the West Shasta District, California: Economic Geology, v. 79, p. 1299-1318.
Deposit

Saleeby, J.B., 1992, Petrotectonic and paleogeographic settings of U.S. Cordilleran ophiolites, in Burchfiel, B. C. and others, editors, The Cordilleran Orogen: Conterminous U.S.: Geological Society of America, The Geology of North America, v. G-3. p. 653-682.
Deposit

Singer, D.A., 1986, Descriptive model of Kuroko massive sulfide, in Cox, D.P. and Singer, D.A., editors, Mineral deposit models: U.S. Geological Survey Bulletin 1693, p. 189-190.
Deposit

Stevens, C.H. and others, 1990, Significance of the provincial signature of Early Permian fauna of the eastern Klamath terrane, in Harwood, D.S. and Miller, M.M., editors, Paleozoic and early Mesozoic paleogeographic relations; Sierra Nevada, Klamath Mountains, and related terranes: Geological Society of America Special Paper 255, p. 201-218.
Deposit

Strand, R.G., 1962, Geologic atlas of California: Redding Sheet: California Division of Mines and Geology GAM 011, scale 1:250,000.
Deposit

Taylor, B.E. and South, B.C., 1985, Regional stable isotope systematics of hydrothermal alteration and massive sulfide deposition in the West Shasta District, California: Economic Geology, v. 80, p. 2149-2163.
Deposit

Tucker, W.B., 1926, Shasta County: California State Mining Bureau 22nd Report of the State Mineralogist, p. 121-216.
Deposit

Watkins, R. and Stensrud, H.L., 1983, Age of sulfide ores in the West Shasta and East Shasta Districts, Klamath Mountains, California: Economic Geology, v. 78, p. 340-343.
Deposit

Brown, G.C., 1913, Field report on Mammoth Mine (File Number 322-5690, CDMG Mineral Resources Files, Sacramento).

General comments

Subject category	Comment text
Deposit	The West Shasta Copper-Zinc District is generally considered to represent stratabound Kuroko-type volcanogenic massive sulfide deposits. The deposits developed, during the Early Devonian within a very depleted (exceedingly more depleted in light rare-earth elements than in heavy rare-earth elements) ensimatic, island-arc regime. The arc formed a submarine volcanic pile consisting of a bimodal suite of low-potassium volcanic rocks, represented by the Copley Greenstone and the overlying Balaklala Rhyolite (Bence and Taylor, 1985). Submarine fumaroles exhaled the ore fluids, which upon mixing with seawater precipitated sulfide minerals. During either a lull in volcanism or a brief interval of radically accelerated ore formation, sulfide precipitation dominated over volcanic sedimentation. The sulfide minerals accumulated in basins as a conformable massive sulfide horizon within the strata of the contemporaneous Balaklala Rhyolite.

Subject category

Comment text

Deposit

The West Shasta Copper-Zinc District is generally considered to represent stratabound Kuroko-type volcanogenic massive sulfide deposits. The deposits developed, during the Early Devonian within a very depleted (exceedingly more depleted in light rare-earth elements than in heavy rare-earth elements) ensimatic, island-arc regime. The arc formed a submarine volcanic pile consisting of a bimodal suite of low-potassium volcanic rocks, represented by the Copley Greenstone and the overlying Balaklala Rhyolite (Bence and Taylor, 1985).

Submarine fumaroles exhaled the ore fluids, which upon mixing with seawater precipitated sulfide minerals. During either a lull in volcanism or a brief interval of radically accelerated ore formation, sulfide precipitation dominated over volcanic sedimentation. The sulfide minerals accumulated in basins as a conformable massive sulfide horizon within the strata of the contemporaneous Balaklala Rhyolite.

Reporter information

Type	Date	Name	Affiliation	Comment
Reporter	04-MAY-2000	Fuller, Michael S. (Higgins, Chris T.)	California Division of Mines and Geology
Editor	01-SEP-2007	Schruben, Paul G.	U.S. Geological Survey	Converted from S&A FileMaker format to Oracle. Edit checks on rocks, units, and ages with Geolex search, and other fields.

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

External references

Wikidata: Q49429310 (Mammoth Mine)

Maps centered on this site

Authoritative California resources

These are landing pages for further research — the state agencies don't currently expose per-mine deep links.