DEPARTMENT OF THE INTERIOR MISCELLANEOUS FIELD STUDIES UNITED STATES GEOLOGICAL SURVEY MAP MF-165Z-A PAMPHLET

MINERAL RESOURCE POTENTIAL OF THE GLACIER PEAK WILDERNESS AND ADJACENT AREAS, CHELAN, SKAGIT, AND SNOHOMISH COUNTIES, WASHINGTON

By

S. E. Church, A. B. Ford, and V. J. Flanigan, U.S. Geological Survey, and R. B. Stotelmeyer, U.S. Bureau of Mines

STUDIES RELATED TO WILDERNESS

Under the provisions of the Wilderness Act (Public Law 88-577, September 3, 1964) and related acts, the U.S. Geological Survey and the U.S. Bureau of Mines have been conducting mineral surveys of wilderness and primitive areas. Areas officially designated as "wilderness," "wild," or "canoe" when the act was passed were incorporated into the National Wilderness Preservation System, and some of them are presently being studied. The act provided that areas under consideration for wilderness designation should be studied for suitability for incorporation into the Wilderness System. The mineral surveys constitute one aspect of the suitability studies. The act directs that the results of such surveys are to be made available to the public and be submitted to the President and the Congress. This report discusses the results of a mineral survey of the Glacier Peak Wilderness (NF031), Mount Baker-Snoqualmie and Wenatchee National Forests, Chelan, Skagit, and Snohomish Counties, Wash. The area was established as a wilderness by Public Law 88-577, September 3, 1964. The study area also includes eight areas classified as proposed wilderness (06031A, D, G) during the Second Roadless Area Review and Evaluation (RARE n) by the U.S. Forest Service, January 1979, and one area (06031C) proposed as an administrative addition.

MINERAL RESOURCE POTENTIAL SUMMARY

Geologic, geochemical, geophysical, and mine and prospect surveys were conducted in 1976-82 to evaluate the potential for mineral resources in the Glacier Peak Wilderness and proposed additions. Eleven areas, covering about 20 percent of the study area, have a moderate to high potential for the occurrence of base- and precious-metal resources. Six properties, two of which are in areas recommended for wilderness addition (06031D and G), contain demonstrated resources for copper, lead, zinc, gold, and silver. The most important demonstrated resource is the porphyry copper-molybdenum deposit at the Glacier Peak prospect, near the center of the wilderness, where drilling has delimited a deposit totaling 1.9 billion tons of mineralized rock. Although porphyry copper-molybdenum deposits are the primary type of deposit that occurs in the study area, areas of potential for the occurrence of precious-metal resources in hot-springs deposits, for the occurrence of base- and precious- metal resources in hydrothermal veins and limestone-replacement deposits, and for the occurrence of copper, zinc, gold, and silver resources in volcanogenic massive-sulfide deposits have also been identified. At 1983 metal prices, none of the mineral deposits in the study area would be mineable; however, at historically high metal prices, portions of the Glacier Peak prospect would be mineable by underground, bulk- mining methods. In addition, the Pioneer property would be mineable, if the inferred reserves are proven, even with dilution due to the narrow vein width. Metal prices substantially higher would be required to cause the Holden and Royal Development mines to be reopened, although additional exploration, particularly at the latter mine, could change the economics of the properties. A low potential for geothermal resources exists on the northeast side of the Glacier Peak volcano, and a cinder resource of 24 million cubic yards is identified at the White Chuck cinder cone, in the wilderness. Because both areas are remote, no reserves were identified. No fossil-fuel resources were identified in the study area.

INTRODUCTION the "study area." Access to the study area is provided by generally well-maintained trails from gravel or dirt Location, access, and geographic setting roads along major valleys above Darrington, Marblemount, Stehekin, Holden, Trinity, and Lake The Glacier Peak Wilderness encompasses Wenatchee. Other than the main access trails across a 464,741 acres, including 483 acres of patented mining few passes (Cloudy Pass, Buck Creek Pass, White Pass, and millsite claims. Also included in the present study and Indian Pass), trails are rough, infrequently are nine areas adjoining the wilderness (fig. 1) that maintained, or nonexistent. total 90,034 acres of recommended wilderness The Glacier Peak Wilderness extends southward additions. All these lands are here collectively called about 40 mi along the crest of the northern Cascade I22°00' I2I°00'

48°30' -

48°00' -

0 30 KILOMETERS

EXPLANATION

Boundary of wilderness

Areas recommended for addition to wilderness

Figure 1. Map showing location of the Glacier Peak Wilderness and adjacent areas, Chelan, Skagit, and Snohomish Counties, Wash. Areas recommended for addition to the Glacier Peak Wilderness are designated by letters: A, area 06031A; C, area 06031C; D, two areas making up addition 06031D; and G, five areas making up addition 06031G. Range, Wash., from the southern border of North intrusions of granitic, dioritic, and gabbroic rock were Cascades National Park. It consists of rugged, highly affected by the metamorphism; some had been varied, mostly alpine terrain cut by numerous deep emplaced prior to metamorphism but others probably river valleys and dominated by the volcanic cone of were intruded during metamorphism. Most of the Glacier Peak (10;541 ft), rising 3,000-4,000 ft above country rocks were intensely deformed during most nearby summits. Though now dormant, Glacier metamorphism. Following metamorphism, fault Peak has been one of the most active Cascade troughs (grabens) and basins developed and were filled volcanoes in the past few thousand years, with minor with sediments eroded from nearby highlands; the activity as recent as the 18th century. The Cascade Chiwaukum graben of early Tertiary age lies just south crest is the drainage divide for waters flowing of the eastern part of the Glacier Peak Wilderness, and westward into Puget Sound and eastward into the the eastern bounding fault (Entiat fault) of the graben Columbia River, and it also forms a climatic barrier. extends northwestward to form a major structural Dense fern, low deciduous brush, and forests of feature within the wilderness. Another of the Douglas fir, western hemlock, and red cedar dominate Cascades major faults, the Straight Creek fault, also the rain forests of the western valleys in sharp of early Tertiary(?) age but of transcurrent type, lies contrast with more open forests of larch and pine on along the west margin of the wilderness and separates eastern slopes. Small glaciers and permanent schist and gneiss of high metamorphic rank from snowfields cover extensive areas along and west of the metavolcanic and metasedimentary rocks of low crest but are rare to the east. The area west of the metamorphic rank to the west. Widespread granitic Cascade crest is in the Mount Baker-Snoqualmie intrusive activity continued through the early Tertiary National Forest, and the area to the east is in the to Miocene time. Miocene granitic magmas intruded Wenatchee National Forest. to very shallow crustal levels, and some may have reached the surface as lavas. The Cascades were Present and previous studies uplifted and deeply dissected by erosion prior to building of andesitic to dacitic volcanic cones, such as Evaluation of the potential for mineral resources Glacier Peak and Mount Baker, in Quaternary time. in the Glacier Peak Wilderness and adjoining areas of wilderness recommendation (fig. 1) was carried out by Mining activity the U.S. Bureau of Mines in 1976-79 and by the U.S. Geological Survey in 1979-82. Work by the U.S. All or parts of five mining districts are within Bureau of Mines consisted of sampling, mapping, and the study area (fig. 2). The Stehekin, Railroad Creek evaluating known mineral deposits and occurrences (Holden), and Chiwawa districts are on the east side of (Stotelmeyer and others, 1982) and reviewing county the wilderness; part of the Cascade mining district is and U.S. Bureau of Land Management mining-claim in the northern part of the study area; and the records. More than 1,300 lode claims and a few placer Sampson district is near the center of the wilderness. claims in the Glacier Peak Wilderness and more than Since 1891, about 1,600 lode claims have been located 300 lode claims in adjacent areas recommended for in the study area. Additional large claim blocks were wilderness addition have been located since staked periodically to cover the deposit at the Glacier prospecting of the region began in the late 1800's. Peak prospect. Work by the U.S. Geological Survey involved three The earliest known mining claims recorded in the separate, but coordinated, lines of investigation: study area apparently were located in 1891 at the head (1) geologic mapping and collection of bedrock samples of the South Fork of Agnes Creek and on the divide (Ford and others, in press); (2) stream-sediment between the Little Wenatchee River and the North geochemical surveys (Church and others, 1982); and Fork of the Sauk River. Surveyors searching for a (3) geophysical surveys using aeromagnetic methods railroad route over the Cascade Range noted (Flanigan and others, 1983) and gravity methods mineralized areas on Railroad Creek in 1887, and J. H. (Sherrard and Flanigan, 1983). Results of extensive Holden prospected the area in 1892. In 1896, he staked mineral exploration programs in and near the study what later became the Holden mine, Washington's area by Bear Creek Mining Co. (Spokane, Wash.) were largest copper mine, which operated from 1938 to made available for the present study (Grant, 1982). 1957. Farther up the canyon, the Crown Point Work by many others, obtained from the extensive molybdenum deposit was probably discovered in 1897 literature on the geology and mineral resources of the or 1898, and a mill and mine camp were constructed. area (Ford, 1983), was also incorporated in the study. Other early claim locations in the study area were made during 1892 on Flat Creek in the northwest Geologic setting corner of the wilderness and on a mineralized area, later to be patented, which was located on the Middle The study area, in the south-central part of the Fork of the Cascade River, in area 06031G. north Cascades, consists of a terrane of crystalline Discoveries were also made south of Trinity in the rocks of great variety and structural complexity Chiwawa River drainage basin, and the Royal (Misch, 1966) that extends from near Stevens Pass Development (Red Mountain) mine in area 0603ID was (U.S. Highway 2) northward into British Columbia and probably discovered after the turn of the century. from the western foothills of the Cascades eastward to The Glacier Peak prospect, the most significant near the Methow Valley and the Okanogan Range. mineral deposit in the study area, was first located as Within this terrane, sedimentary and igneous rocks of a vein occurrence about 1900 by Sampson Mining Co. early Paleozoic, or older, to Mesozoic age were Early exploration of the property was by short adits transformed into schists and gneisses during one or following copper-rich shear zones. Later exploration more phases of regional metamorphism, the latest utilized diamond drilling and revealed a huge occurring near the end of the Mesozoic Era. Many disseminated porphyry copper-molybdenum deposit. 48° 121°30' 121°00' 120°30' 30' j - SCADEST" JORDAN LAKES AND CYCLON LAKE PLUTONS

MAP LOCATION

Stehekin

RAILROAD CREEK MINING DISTRICT

Approxtrn of Glacier Peak Wilderness 48C 00' Approximate boundary of > areas of recommended /, wilderness addition \ V.A

10 MiLES

EXPLANATION

Volcanic and volcaniclastic rock (Quaternary) Axis of transverse structures (Grant, 1969) Granitic rock and porphyry (Miocene) Approximate boundary of mining district Granitic rock and granitic gneiss (Tertiary and ^ Mine Cretaceous) Foliated diorite and gabbro, schist and gneiss X Mineral prospect (Pre-Tertiary) >ntc Hot spring Fault Figure Z. Map showing location of mining districts and major mineral deposits and their relation to the regional structural belts defined by Grant (1969). 4 Bear Creek Mining Co., the exploration subsidiary of Stotelmeyer and others, 1982), the most important Kennecott, completed confirmation drilling in 1959, deposits are the porphyry-copper type accompanied by although additional exploration and patent application peripheral hydrothermal veins associated with granitic holes were drilled as late as 1970. rocks and porphyritic phases of shallow-level Miocene plutons. ACKNOWLEDGMENTS Two principal episodes of major, nedium- to high-rank regional metamorphism affected the The results of a large project such as this are sedimentary and igneous rocks of this part of the north never wholly the authors' alone. We wish to thank Cascades (Misch, 1966, 1977). One metamcrphic event many co-workers and assistants for their diligent occurred about 415 m.y. ago in the early Paleozoic, efforts in the sample collection and mapping and the other about 60-90 m.y. ago near the end of the completed during this study. We thank Peter Misch, Cretaceous (Mattinson, 1972). Original ages of pre- University of Washington, and A. R. Grant for office Upper Cretaceous rocks are, in general, poorly known and field consultations, and R. C. Babcock, Jr., vice- because of extensive resetting of mineral ages by the president, Bear Creek Mining Co., for permission to younger metamorphism. Mattinsor's (1972) use company data. In particular, the field studies of uranium-lead ages from zircons of about 220 m.y. for many previous workers (Ford, 1983) were invaluable in the Marblemount Meta-Quartz Diorite of Misch (1966) compiling the geologic data. Claude McLean and Fred and the Dumbell Mountain plutons of Cater and Schaub, Darrington Ranger District, and Glenn Crowder (1967) show that granitic intrusive activity Hoffman, Lake Wenatchee Ranger District, provided began at least as early as the Triassic. T ~se bodies U.S. Forest Service facilities and data for the study. form a northwest-trending central belt ir the study We also thank Keith Miller, Superintendent, for area (unit pTqd), extending from the Cascade River in permission for helicopter landing in the North Cascade the north to east of Trinity. Extensive intrusive National Park areas adjoining the Glacier Peak activity also occurred about 90 m.y. ago in the Late Wilderness and the U.S. National Park Service Cretaceous, according to Mattinson's (1972) uranium- personnel at Stehekin for their cooperation and use of lead ages for the Eldorado Orthogneiss of Misch (1966) their facilities. We thank R. B. Dickinson for access and potassium-argon and uranium-lead ages reported to the Royal Development mine and Charles Isreal, by Tabor and others (1980, 1982) for tl ? Tenpeak caretaker at Trinity, for the use of camp facilities. pluton and Sloan Creek plutons. Two largo plutons of Fieldwork could not have been completed in this dioritic, quartz dioritic, and tonalitic to gabbroic difficult alpine terrain without the skillful work of our composition (Chaval and Riddle Peaks plutons) are helicopter pilots, Anthony Reece, Gary Lot, LeRoy undated, but their involvement in regional Brown, Ben Van Etten, Michael Wood, and the late metamorphism also suggests a pre-Tertiary age. Jack Johnson. We are indebted to our co-workers, Numerous radiometric ages show that major granitic W. H. Nelson, R. A. Sonnevil, R. A. Loney, R. A. intrusive activity continued through the early Tertiary Haugerud, S. L. Garwin, and the late Carl Huie; (Railroad Creek and Duncan Hill plutons and other E. L. Mosier, J. M. Motooka, J. G. Frisken, smaller ones) and into the Miocene (Cloudy Pass and R. S. Werschky, R. C. Bigelow, George VanTrump, Jr., Buckindy plutons and related smaller bodies). Sulfide A. D. McCollaum, B. F. Arbogast, C. M. McDougal, mineralization is chiefly associated with the Miocene W. R. Willson, and J. G. Evans; the late Mark Sherrard; plutons and, to a lesser extent, with the Riddle Peaks and F. L. Johnson, E. L. McHugh, F. E. Federspiel, and possibly a few other plutons. Many large plutons, D. K. Denton, Jr., and S. A. Stebbins for their diligent including the Tenpeak, Sloan Creek, Sulphur Mountain, efforts to complete parts of the Glacier Peak folio High Pass, Jordan Lakes, Chaval, Cyclone Lake, (MF-1652), so necessary as the raw-data base for this Downey Creek, and Railroad Creek plutons, show little assessment of potential mineral resources. Finally, we or no evidence of associated hydrothermal thank our colleagues (Erickson, 1982; Cox, 1983) for mineralization. their open discussions of the geologic, geochemical, Numerous, mostly high-angle, faults cccur in the and geophysical characteristics and peculiarities of study area, but two of regional magnitude are mineral deposits. dominant: the Entiat fault in the interior and the Straight Creek fault near the west margin cf the study GEOLOGY, GEOCHEMISTRY, AND GEOPHYSICS area. The Entiat fault extends from the study area at PERTAINING TO least 30 mi southeastward to near Wenatchee, where it MINERAL RESOURCE ASSESSMENT forms the east-bounding fault of the Chiwaukum graben. To the north, in the study area, the Entiat Geology fault was intruded by the Cloudy Pass pluton. In pre-Miocene time, the Entiat fault probably continued The Glacier Peak study area transects the north of the Cloudy Pass pluton as th? LeConte crystalline core of the north Cascades, a structurally Mountain fault. The Straight Creek fault, which is a complex and highly varied metamorphic and plutonic probable strike-slip fault, is cut by a Miocene pluton terrane of Mesozoic and older units (Misch, 1966, (Grotto batholith) and extends northward and 1977). These units were extensively intruded by southward beyond the limits of the study a^ea (Misch, Tertiary granitic plutons, some as young as Miocene. 1966, 1977; Tabor and others, 1982). Many mineral The study area occupies a southward projection of the properties and occurrences are near the Entiat fault, area of copper-molybdenum porphyry deposits of but none occur near the Straight Creek fault within predominantly Tertiary age in the Canadian cordillera the study area. (Christopher and Carter, 1976). Among the numerous The distribution of prospects, deposits, and prospects, mineral occurrences, and deposits of varied known mineral occurrences described by Grant (1982) type known in the study area (Grant, 1982; and Stotelmeyer and others (1982) shows a marked concentration in the east-central part of the 1969). Distribution of these breccias and the 24.5 m.y. wilderness, northeastward from a line approximately age of granodiorite at Trinity (Engels and others, 1976) along the Chiwawa River, through Glacier Peak strongly suggest that the Cloudy Pass pluton underlies prospect to the Mount Buckindy area. In that sector, the Swakane Biotite Gneiss along Phelps Ridge. many mineral properties are in or near two of Grant's Pipelike bodies of intrusive breccia associated with (1969) mineralized "transverse structural" belts, or porphyry plugs cut biotite gneiss in the roof of the lineaments (see fig. 2). The belts trend northeastward Buckindy pluton at Mount Buckindy. Breccias of across the dominant northwest-trending structural probable explosive origin also occur near th,e roof of grain and are characterized by closely spaced the Cascade Pass dike, an apparent northeastward subvertical joints, en-echelon fractures, and shears extension of the Buckindy pluton. The sliphtly that Grant (1969) considered to be high-level different ages of the Cascade Pass pluton (18 rn.y., expressions of deep crustal movement. Engels and others, 1976) and the Buckindy plutor (15 Many mineral properties and prospects in the m.y., R. J. Fleck, written commun., 1982) indicate study area are in the Buckindy belt. These include the that they may be separate intrusions. Most areas of Mount Buckindy, Milt Creek, Michigan, Skagit, Pioneer significant mineralization, including the Glacier Peak (Epoch), and Grand Republic properties (Stotelmeyer deposit on Miners Ridge, properties on Phelps Ridge, and others, 1982), of which the most significant are and the Pioneer and Mount Buckindy properties, o~cur the Mount Buckindy and Pioneer. Mineral properties in granitic rock, porphyry, or country rock near the that are in the Glacier Peak belt include the Glacier roof of intrusive bodies. Deeply eroded parts of the Peak porphyry copper-molybdenum deposit along plutons generally appear barren of mineralization. Miners Ridge, the Deerfly, Fortress Mountain, Venting of the Miocene magma chambers may Esmeralda, and Copper Point prospects, and the Crown have included the eruption of magma forming the Point mine. These properties and prospects occur in or volcanic deposits of Gamma Ridge (Tabor and near the youngest dated (Miocene) plutons of calc- Crowder, 1969). Although they have not been dated, alkaline tonalite, granodiorite, and some granite; small bodies of volcanic rocks near Ross Pass, on properties in the Buckindy belt are associated with the northern Lyall Ridge, near Round Lake, and elsewhere Buckindy pluton and the Cascade Pass dike of Tabor may be of similar origin. (1963), and properties in the Glacier Peak belt are Although the dominant mineralization of associated with the Cloudy Pass pluton. Porphyry porphyry copper-molybdenum type known in the study copper-molybdenum deposits occur in hosts of similar area was clearly related to the Miocene plutorism, type in the Canadian cordillera, where metallogenic other types of mineral deposits may be related to epochs of the porphyry-ore formation are dated at earlier igneous or, possibly, metamorphic events. The 200-195 m.y., 185-175 m.y., 155-140 m.y., 80-65 m.y., deposit at the Holden mine, for example, occurs in a 50 m.y., 40-35 m.y., and 26-18 m.y. in age (Christopher belt of schist and gneiss that extends through the east- and Carter, 1976). Potassium-argon ages of the central part of the study area. The deposit shows no Buckindy pluton (R. J. Fleck, written commun., 1982), conclusive relation to plutons in the vicinity ard is Cascade Pass pluton (Engels and others, 1976; and considered by DuBois (1954) to be related to high-rank R. J. Fleck, written commun., 1982), Cloudy Pass regional metamorphism. A gangue mineral from the pluton (Tabor and Crowder, 1969), and of granodiorite mine, phlogopite, gave an age of 44.1 m.y. (Engels and from the Royal Development mine(?) (Engels and others, 1976), which is younger than the latest regional others, 1976) are within or near the youngest episode metamorphism in Cretaceous time, but older thar the of the Canadian mineralization. Other, generally Miocene plutonic events that formed the Glacier Peak undated, small bodies of porphyry occur widely through deposit. The deposit is near the north end of the mainly the eastern part of the study area. The plug at Duncan Hill pluton (Cater, 1982), which has yielded Old Gibb Mountain yielded an older age of 43.9 m.y. potassium-argon ages in the range of 46-43 m.y. (Cater and Crowder, 1967), indicating a considerable (Engels and others, 1976), spanning the age of the age span for intrusive activity. However, though Holden gangue. This age equivalence may reflect undated, many small bodies of porphyry are believed to thermal resetting of the phlogopite by contact be related to the larger plutons dated as Miocene, metamorphism rather than showing a direct relation of including many around the periphery of the Cloudy the Holden deposit to the Duncan Hill pluton. Pass pluton that are too small to delineate at The Riddle Peaks pluton is mostly hornblende- 1:100,000 scale. Some of these satellite plutons are, bearing, layered gabbro (Cater, 1982) and contains five or appear to be, related to known mineral occurrences small claims in oxidized and mineralized rock. in the wilderness between Phelps Creek and the Disseminated sulfide and iron-titanium oxide minerals Chiwawa River. are common in the gabbro, but concentrations of r^ore Large areas of both the Buckindy and Cloudy than a few modal percent have not been found. Bodies Pass plutons appear barren of significant sulfide of this type may contain inconspicuous but significant mineralization. Both are shallow-level intrusions amounts of platinum-group metals, commonly in small containing breccias that suggest explosive venting of segregations that are difficult or impossible to identify late-stage, volatile-rich fluids. Intrusive breccias are without more detailed geochemical and microscopic particularly common in and near the southern and studies. Chromite lenses, a common igneous eastern parts of the Cloudy Pass pluton (Cater, 1969); association in other layered gabbroic plutons, have not they also occur in the northern parts of the pluton been identified in this pluton. Finally, numerous, (Grant, 1966). Numerous masses of sulfide-bearing and mostly small, bodies of metaperidotite or other altered breccia on Phelps Ridge, located in the ultramafic rocks, some of which contain prospects, are wilderness between Phelps Creek and the Chiwawa widely scattered in a central schist belt in the study River, are closely associated with porphyry plugs that area. are probably related to the Cloudy Pass pluton.(Cater, Geochemistry coincident with the Glacier Peak transverse structural belt. Many local magnetic anomalies ranging from a A geochemical survey was made during the few tens to several hundred gammas can be spatially summers of 1979 and 1980. Collection of stream related to plutonic rocks mapped at the surface. sediments, supplemented by heavy-mineral- Known mineral deposits in the study area show concentrate samples panned from stream sediments, three types of spatial relationships with tl e magnetic constituted the reconnaissance phase of the anomalies. One group of prospects seems to be investigation. Samples were collected primarily from spatially related to northwest-trending magnetic first-order-stream drainage basins representing areas lineaments or linear zones of steep magnetic gradient; of 1-Z mi , although some represent larger drainage the Holden mine is a good example. A second group of basins. The minus-80-mesh fraction (<177 micro­ prospects seems to be spatially related to the outer meter) of the stream-sediment samples was separated perimeter, or flanks, of magnetic anomalies associated for analysis. with some of the Cretaceous and younger plutons such Emission spectrography was used for most of the as Riddle Peaks and Mount Buckindy plutons. The analytical work (Church and others, 198Z, 1983a), Mount Buckindy and Milt Creek prospects are typical although a new method, a partial digestion in aqua of this second class. The third group of prospects is regia followed by analysis using an Inductively Coupled along the east-west magnetic low that p=urallels the Plasma-Atomic Emission Spectrometry (ICP), was also axis of the Cloudy Pass pluton; the Glacier Peak, applied to the stream sediments (Church and others, Deer fly, and Fortress Mountain prospects are the most 1983c). Mineralogical studies (Church and others, significant of this group. 1982, 1983a) were made of the nonmagnetic heavy- mineral concentrates collected in 1980. Representa­ MINING DISTRICTS AND MINERALIZATION tive suites of rock samples were collected from each major formation and were analyzed to determine U.S. Bureau of Mines personnel examined mines, thresholds for each of the geologic terranes (S. E. prospects, and claims in and near the study area Church, unpub. data, 1983). Studies of altered zones (Stotelmeyer and others, 1982). More than 100 sites not previously defined (Grant, 1982), as well as were examined during the study, and 890 lode samples detailed sampling of mineralized areas, were used to were taken from mine and prospect workings, define elemental suites indicative of mineralization. outcrops, stockpiles, and dumps (data on file at the Anomalous elemental concentrations in stream U.S. Bureau of Mines, Western Field Operations sediments were defined from these data. The suite Center, Spokane, Wash.). Our investigations indicate comprising copper, molybdenum, tungsten, gold, that the study area is relatively une?~olored for cobalt, lead, zinc, and silver is associated with the minerals. Until recently, a combination of porphyry-copper mineralization at the Glacier Peak geographical and geological factors adversely affected deposit and is a common association for porphyry- prospecting and exploration: the harsh environment no copper systems in the Canadian cordillera (Pilcher and doubt was one of the factors, but tl ^ lack of McDougall, 1976). The suites comprising lead, silver, bonanza-type oxide and secondary mineralization, and zinc; lead, arsenic, and antimony; and lead, silver, resulting from recent glaciation and rapid erosion, and molybdenum are found in the northeastern part of discouraged early prospectors. In more recent years, the study area and represent base-metal and precious- large companies capable of financing exploration for metal hydrothermal systems. huge, low-grade primary deposits in the igneous rock, or of delineating the erratic occurrences of the rich, Geophysics pod-shaped sulfide deposits in the metamorphic rock requiring detailed geophysical studies, have been Data obtained from an aeromagnetic survey excluded from the area because of environmental flown specifically for this study were added to existing constraints. data (Flanigan and others, 1983); the magnetic data Results of our mine and prospect evaluation are were collected along northeast-southwest flight lines briefly summarized below for each mining district (fig. spaced 0.5 mi and 1.0 mi apart at 1,000 ft terrain 2). Properties having identified metallic resources are clearance. listed in table 1, and mines and prospects having Several of the magnetic features seen in the possible undiscovered metallic resources are described composite aeromagnetic data may be associated with in table 2. Numbered property locations are from the geologic features, some of which may be important mines and prospects report by Stotelmeyer and others indicators of mineralization. A regional belt of (in press), who also described other properties magnetic anomalies, both highs and lows, that trends examined during the study. There is no cur-ent mining north-northwest across the northeast part of the study activity in the study area. area is associated with a belt of plutonic and metamorphic rocks along the Entiat fault. Major Sampson district transverse structural zones trending N. 30°-90° E. are reflected by the northeast alinement of magnetic The Sampson district, in Snohomish County anomalies associated with the Mount Buckindy and immediately west of the Cascade Range crest, is the Cascade Pass plutons (Grant, 1969). These anomalies most important mining district in the study area. This define the Buckindy belt. An east-west magnetic low, small district in the center of the wilderness contains within the magnetic high defined by the Cloudy Pass only two properties; it is accessible only by trail or pluton, crosses the southern part of the pluton near the helicopter. In the early 1940's, the Glacier Peak Glacier Peak deposit and extends eastward beyond deposit was recognized as a low-grade, large-volume Holden. This magnetic signature characterizes porphyry-copper deposit. It is characterized by mineralization within the Cloudy Pass pluton and is disseminated and stockwork copper and irolybdenum mineralization. A smaller, but similar, deposit of this Stehekin district type may underlie Fortress Mountain about 2 mi southeast of the Glacier Peak prospect where granitic The Stehekin mining district lies principally rocks have also intruded gneiss host rock. The Deer fly northeast of the Glacier Peak Wilderness. Only the prospect, a peripheral precious-metal vein deposit, part southwest of the Stehekin River is in the sf-dy contains indicated and inferred resources of silver, area, and there has been no mining in this part of the gold, and copper (table 1). The district has had no district. This area has been little explored for mineral production and is currently inactive. Eighteen minerals despite the intensity of mineralization, patented claims, consisting of 360 acres in the Suiattle probably because of the difficult access. River drainage basin, cover the Glacier Peak deposit. Cascade district Chiwawa district About half the Cascade mining district is in the The Chiwawa district includes the Chiwawa, study area; the rest is in North Cascades National White, Napeequa, and Little Wenatchee River drainage Park. Only the section containing the Middle Fort of basins. Formerly, the districts were part of the much the Cascade River and the lower part of the South larger Leavenworth mining district. Access is by Fork of the Cascade River was studied. The district all-weather roads, and the main mining and contains the Pioneer patented claim group (9 claims, mineralized areas in the study area are relatively 179 acres). Indicated and inferred silver, lead, and accessible by trail. zinc resources occur in a hydrothermal vein deposit in The Royal Development, or Red Mountain, mine area 06031G. Also at the north end of the wilderness, is in area 0603ID. The ore occurs in a mineralized the patented claim group of the Johannasburg mine breccia pipe at or near the contact of granitic and extends into area 06031G. A small amount of metamorphic rocks. Copper, silver, and gold were high-grade lead-silver ore was produced in 1953 and produced between 1929 and 1940, and the total output 1955, most likely from that part of the claim group was about 18,000 tons of ore, from which about inside North Cascades National Park. 215,000 Ibs of copper, 17,000 oz of silver, and 29 oz of gold were recovered. Active exploration was under­ ASSESSMENT OF MINERAL RESOURCE POTENTIAL way in 1981 at this property. Seventy-four claims of the 142-claim group at the Royal Development mine Three types of commodities have been examined extend into the wilderness. Thirty-eight claims in the in the mineral resource evaluation of the study area: group are in area 0603ID, nine of which are patented metallic resources, nonmetallic resources, and energy (180 acres); the rest of the claims in this group are resources. adjacent to area 0603 ID. The classification of mineral resources for known Elsewhere in the district, there is evidence for a deposits found in the study area was made using the porphyry copper-molybdenum deposit or a breccia-pipe terminology of U.S. Geological Survey "Circular 831" deposit (Esmeralda property) to the north, along Phelps (U.S. Bureau of Mines and U.S. Geological Survey, Ridge within the wilderness. There are six patented 1980). The classification of the mineral potential of claims and one mill site in the wilderness along Phelps an area, however, represents an integration of Creek. measurable data and the subjective evaluation of the Production records also suggest that about 7,000 degree to which those data, and the interpretatior of tons of pumice may have been produced between 1943 the geologic conditions inferred, represent a known and 1947 from a small open pit southeast of the Royal mineral deposit type. We use three terms, "hiph," Development mine. "moderate," and "low," to describe the potential for mineral resources of certain areas within the study Railroad Creek district area. An area having a high potential for mineral resources is one in which most of the geologic criteria Railroad Creek drains part of the eastern portion outlined in applicable mineral-deposit models are of the Glacier Peak Wilderness and empties into Lake met. Furthermore, a deposit of that general type and Chelan. Between 1938 and 1957, the Holden mine pro­ age must exist in the western Cordillera. An area duced about 10 million tons of ore that yielded more having a moderate potential is one in which the than 212 million Ibs of copper, 40 million Ibs of zinc, 2 geologic criteria permit a particular deposit type, but million oz of silver, and 600,000 oz of gold. The in which the geochemical or geophysical evidence for wilderness boundary is at the western edge of the mineralization is less well defined; however, a Holden townsite. All material, supplies, and personnel reasonable chance for the occurrence of concerted for the Holden mine were brought 45 mi by barge from mineral deposits exists. An area having a low Chelan or flown in by float plane to Lucerne and then potential is one for which the data do not indicate trucked 12 mi to the mine site. A shuttle bus is geologic conditions favorable for ore accumulations. presently operated between Lucerne and Holden, which Some areas of low potential are tentatively classified is now a church camp. as such on the basis of limited data. An area of low Recorded mineral production from within the potential may include areas of concealed mineralised wilderness is molybdenum ore from the Crown Point rock as well as areas of dispersed mineral occurrences. mine on upper Railroad Creek. Output was reported to be 10-12 tons in 1901-02, and small amounts of ore Potential for metallic mineral resources were also produced between 1903 and 1917. Currently, there is one claim on a silver-bearing In the evaluation of metallic resources of the quartz vein (Ideal prospect, fig. 2) in the wilderness, on study area, we draw heavily on previous studies of the east side of Bonanza Peak. mineralization and on our collective experience and Table 1. Mines and prospects with estimated metallic resources in the Glacier Peak Wilderness and adjacent areas, Chelan. Skaglt. and Snohomish Counties", Washington [Underlined names refer to properties having a high probability for undiscovered resources]

No. Tonnage Resource on Property Type (except where classification' Commodity r-rade map noted) Sampson mining district

48 Glacier Peak Disseminated copper- 1.9 billion Total identified Copper 0.334 percent molybdenum. resource. Molybdenum disulfide 0.15-0.02 percent

41.3 million Measured restricted Copper 0.71 percent reserve. Molybdenum disulfide 0.046 percent Gold 0.015 oz/ton Silver 0.25 oz/ton Tungsten trioxide 0.03 percent

46 Deerfly (probable Disseminated silver- 174,000 Indicated and Silver- 0.75 oz/ton extension of inferred; Gold 0.005 oz/ton Glacier Peak subeconomic. Copper- 0.05 percent prospect).

Railroad Creek mining district

38 Ideal Fissure vein- 34,000 Indicated and Silver- 1.42 oz/ton inferred; marginal reserve.

43 Crown Point mine Shear zones- 1,300 Measured and Gold trace Indicated; Silver 2.92 oz/ton subeconomic. Copper 2.6 percent Lead 0.39 percent Zinc 0.72 percent Molybdenum disulfide 0.06 percent

23 Hoi den mine A. Shear zones 3 million Measured; indicated Copper- 1.1 percent (adjoins (underground). and inferred; Gold 0.06 oz/ton Wilderness). marginal reserve. Silver- 0.2 oz/ton Zinc 0.3 percent

B. Tailings pile 9 million Measured; marginal Gold 0.048 oz/ton reserve. Silver 0.1 oz/ton Copper 0.07 percent Zinc 0.3 percent Pyrite (recoverable) 5.0 percent Silica (free SiOg) unavailable

Cascade mining district

7 Pioneer (area Fissure vein 734,000 Indicated and Silver 6.46 oz/ton 06031G). (1.5 ft wide). inferred; Lead 6.4 percent restricted reserve. Zinc 6.5 percent Copper 0.52 percent Gold 0.015 oz/ton

5 Silver Queen Sulfide (limestone- 60 (first pod) Occurrence Silver 5.35 oz/ton (adjoins replacement forming Lead 5.0 percent Wilderness). two pod-shaped ore Zinc 2.0 percent bodies). Copper 0.40 percent Gold 0.01 oz/ton Cadmium 0.01 percent

9 (second pod) do Zinc 12.0 percent Cadmium 0.18 percent Silver 0.95 oz/ton Copper 0.17 percent Lead 0.65 percent

Chiwawa mining district

64 Royal Development Breccia pipe- 8.5 million Inferred; marginal Copper 0.4 percent mine (area reserve. Silver 0.9 oz/ton 060310). Tungsten unavailable

^Numbers correspond to locations shown on accompanying map, MF-1652-A. 2U.S. Bureau of Mines and U.S. Geological Survey (1980). Table 2. Mines and prospects with possible undiscoveredSkag1- t> an() metallicsnohomlsh resources Counties, In Washingtonthe Glacier Peak~~ Wilderness and adjacent areas, Chelan,

[Properties are not sufficiently exposed or studied to enable estimate of tonnage and grade] No. Sampl 1 ng on . Property Type Commodities Description and remarks (sample lengths are map In parentheses) Stehekln mining district Sulflde Lead On mineral belt extending to Nineteen samples: ten ranged from 0.74 to 6.9 percent (limestone- Zinc Hoi den mine. May Intersect lead (5.0 and 4.0 ft, respectively) and averaged 2.0 replacement). Silver Copper King structure. Several percent; twelve ranged from 0.81 to 7.0 percent zinc Copper shallow prospect pits. (4.0 and 2.0 ft, respectively) and averaged 3.0 percent; Cadmium byproduct nine ranged from 0.9 to 3.7 oz silver per ton (2.0 and 15.0 ft, respectively) and averaged 2.1 oz; six ranged from 0.10 to 0.53 percent copper (2.0 ft) and averaged 0.29 percent. 36- Copper King Shear zone Copper Two adits, 5 ft and 14 ft long. Seven samples: one assayed 0.34 percent cobalt, 0.11 per­ Cobal t Possible ore shoot may occur at cent copper, and 0.5 oz silver per ton (1.2 ft); one Silver byproduct Intersection of this zone with assayed 0.36 percent copper and 0.3 oz silver per ton trend of Carmen deposit. Cobalt (0.8 ft); one grab sample assayed 0.26 percent cobalt. may be only localized. 32 GoeHcke Porphyry copper Copper Rugged terrain Inhibits prospect- Fifteen samples: one sample of float assayed 4.4 percent Silver 1ng; on Hoi den trend. copper and 1.0 oz silver per ton; another sample of float assayed 0.9 percent copper; one chip sample assayed 1.2 oz silver per ton (2.0 ft); twelve samples of accessible parts of numerous pyrltized areas on ridge crests were essentially barren. Railroad Creek mining district 29 Mary Green-- Shear zones Copper Copper-rich pockets. Potential for Twenty-five samples: two of nine samples at workings near Silver byproduct limestone replacement; on Hoi den the ridge crest contained 1.5 percent copper (3.0 and trend. Three adits as much as 3.2 ft), another contained 0.14 percent copper (4.0 ft), 370 ft long and several prospect and all ranged from 0.1^to 0.5 oz silver per ton. Six­ pits. teen samples from across isolated patches of pyrltized rock along the canyon slope Indicated no other anomalous mineral concentrations. 44 Victor Fissure vein Silver Sulflde velnlets. Possible exten- Five samples: one assayed 1.5 oz silver per ton, 1.4 per­ Lead slon of Crown Point mine. A cent lead, 4.0 percent zinc, 0.04 percent cadmium and Z1nc 92-ft adit. 0.25 percent copper (0.2 ft); another assayed 1.4 oz silver per ton, 1.9 percent lead, and 0.60 percent zinc (0.2 ft). 24 Sevenmlle- Vein- Antimony Exploration target only. Also Seven samples: one of three samples from the 1953 exami­ Antlmony Gold byproduct examined by U.S. Bureau of Mines nation contained 2.72 percent antimony, and one sample (adjoins Silver byproduct 1n 1953. Caved adit 50 ft long. assayed 1.0 percent nickel (no widths given); two of w11der- four samples from the 1977 examination assayed 0.48 and ness). 0.31 percent antimony (select and grab samples, respec­ tively); gold assayed from a trace to 0.01 oz per ton, and silver assayed from 0.2 to 0.4 oz per ton in those four samples. Chiwawa mining district

53 Copper Point Shear zones and Gold Patented claims. About 14 short Eighty samples: fifteen assayed significant silver, possible breccia Silver adits and numerous prospect pits. ranging from 0.4 oz per ton (0.5 ft) to 5.1 oz per pipe. Copper Shear zones are very narrow. ton (0.6 ft) in chip samples, and 8.8 oz per ton in Lead Contact of Entiat fault and ^ select sample; ten chip samples assayed from 0.10 Zinc Cloudy Pass pluton. to 0.47 percent copper (0.6 to 1.0 ft, respectively), and eight select or grab samples assayed from 0.15 to 5.3 percent copper; six samples contained greater than 0.75 percent lead, ranging from 0.76 to 3.9 percent (0.5 and 0.6 ft, respectively); five con­ tained greater than 0.75 percent zinc, ranging from 0.83 to 2.0 percent (0.6 and 0.3 ft, respectively); eighteen samples contained measurable gold, assaying from 0.01 to 0.05 oz per ton (1.0 ft). 56 Esmeralda Porphyry copper Copper Widespread hydrothermal-alteration Forty-two samples: nine assayed 0.1 percent or more or breccia Gold area containing disseminated of copper, ranging from 0.16 to 2.2 percent (2.0 and pipe. Silver sulfides, and locally containing 1.2 ft, respectively); fifteen samples contained high grade gold and silver measurable gold seven chip samples assayed from 0.01 deposits at possible ancient to 0.15 oz per ton (1.1 and 1.2 ft, respectively), three fumaroles or boiling centers. select samples assayed 0.04 oz, 0.14 oz, and 0.37 oz per Workings consist of five adits, ton, and five grab samples assayed from 0.01 to 0.04 oz two shafts, and at least six per ton; nine samples had assays ranging from 0.5 to 4.8 prospect pits. oz silver per ton (1.0 and 1.2 ft, respectively); six samples had an arsenic content greater than 1.0 percent, assaying as high as 29.0 percent in a select sample and 24.0 percent in a chip sample (1.2 ft). 57 Peacock- Epithermal Silver Small deposits. Possible exten­ Four samples: one select sample assayed 5.3 oz silver per deposit. Gold sions of Esmeralda deposit. ton, 0.07 oz gold per ton, 0.51 percent copper, and 27.0 Copper Several prospect pits. percent arsenic; another sample assayed 1.4 oz silver Arsenic per ton.

Sampson mining district 51 Fortress Porphyry copper Copper May be extension of Glacier Peak Five grab samples of talus: one assayed 0.15 percent Mountain. prospect. copper. Of more than 150 company surface samples, 25 assayed greater than 0.2 percent copper. Several shallow drill holes; the best averages 0.34 percent copper (87 ft). unrecognized mining districts

21 Cougar- Disseminated Gold Pyritized rhyodacite plug at least Eight samples: four chip samples assayed from 0.01 to Mountain Copper 750 ft in diameter. Probably 0.03 oz gold per ton; (0.1 and 3.3 ft); one assayed 0.14 Lion. Zinc extends into wilderness, 1,000 ft percent copper (3.3 ft); a select sample assayed 0.17 to the west. Two adits 30 and 41 percent zinc. ft long. 92 Goff (area Unknown Copper Altered area of several square Twenty-nine samples: four samples at the 5-ft adit 06031A). Silver miles, containing small, local- assayed as much as 2.5 oz silver per ton, 0.01 oz gold Gold ized, sulfide-bearing shear zones. per ton, and 0.05 percent copper in veinlets as much as Four adits: 105 ft, 80 ft, 10 ft, 0.3 ft wide. Company reported 2 ft assaying 13.85 oz and 5 ft long; a 62-ft trench; at silver per ton, and 8.3 percent copper. Their location least four p-ospect pits. is "vj-se. 2 Mount Porphyry copper Copper Remote, glacier-covered area. The best hole averaged 0.337 percent copper and 0.13 Buckindy. Molybdenum Company drilled five holes. percent MoS2 over 425 ft. Two intervals, 9 and 10 ft Silver byproduct long, assayed more than 1 percent copper.

^Numbers correspond to locations shown on accompanying map, MF-1652-A. that of our colleagues. The following summary is silicification, and brecciation. Deposits are generally based on the recognition of specific geologic, associated with caldera margins, normal faulting, or geochemical, geophysical, and mines and prospects complex volcanic centers characterized by presence of criteria characteristic of a distinct deposit type small intrusive plugs. Disseminated pyrite is (Erickson, 1982; Cox, 1983). In evaluating areas of common. Altered rocks and stream sediments have mineral potential, we have developed recognition moderate to high levels of arsenic, antimony, mercury, criteria as defined by a mineral-deposit model, gold, and silver. Barite is common in the formulated those criteria in definable terms, and heavy-mineral concentrates. The type area for the~e summarized our observations for mineralized areas in deposit is in the Great Basin. Similar deposits have the study area. This approach is model dependent; recently been found in the Eocene Chumstick should new mineral deposit models become more formation along the extension of the Entiat fault south appropriate based on future study, the Glacier Peak of the study area, near Wenatchee, Wash. folio (MF-1652) should provide the basic observational Five areas (A-l to A-5, fig. 3) may possibly have data for new resource assessments. hot-springs-type deposits: Gamma Ridge-Gamma Hot The models for deposit types used in this Springs, Goff (06031 A), the Round Lake volcanics area evaluation are presented in tables 3-6 using the (06031G), Kennedy Hot Springs, and Sulphur Hot following general recognition criteria: Springs. The data for each area are summarized in table 3. Four of the five areas considered do not 1. Regional geologic setting and structure. sufficiently satisfy the deposit criteria to consider 2. Local geologic environment, including rock them as having a moderate potential for the type, structural relationships, alteration, occurrence of precious-metal resources. Although the and observed mineralized rock. Goff prospect (A-l) has anomalous concentrations of 3. Geochemistry of rocks, stream sediments, the precious metals, it lacks many of the essential heavy-mineral concentrates panned from features of the hot-springs-deposit model, including stream sediments, and mineralogy of the evidence of extensive silicification or the presence of heavy-mineral concentrates. a venting hydrothermal system. Likewise, the Rou^d 4. Geophysical expressions indicated by the Lake volcanics area (A-2) lacks many essential aeromagnetic and gravity surveys. features. Both areas are classified as having a low 5. Evidence of mining activity, known deposits, potential for the occurrence of precious-metal and exploration and claim activity. resources in this type of deposit. Two of the thr^e active hot-springs areas, Kennedy (A-4) and Sulphur Detailed descriptions of the specific recognition Hot Springs (A-5), also lack essential features of the criteria used for each model type are given below, model, primarily the close spatial association with along with specific references to geologic descriptions contemporaneous volcanic-vent areas. These tvo or summaries of features of that deposit type. areas also have a low potential for the occurrence of The principal types of mineral deposits that precious-metal resources in a hot-springs deposit. T"«» occur, or may be expected to occur, in the study area Gamma Ridge-Gamma Hot Springs area (A-3) probal *y are (A) hot-springs deposits (Au and Ag); (B) base- and represents a hot-springs system related to recent precious-metal hydrothermal-vein deposits and volcanic activity at Glacier Peak that vented through limestone-replacement deposits associated with the older volcanic rocks (Tabor and Crowder, 1969, igneous intrusive rocks (Au, Ag, Pb, Zn, Cu, and As); p. 22-23). The presence of silicified rock, lar^e (C) disseminated porphyry deposits of both the copper- altered areas, and favorable geochemical anomalies rich and molybdenum-rich type (Cu, Mo, W, and Au); suggests that area A-3 has a moderate potential for (D) volcanogenic massive-sulfide deposits in the the occurrence of precious-metal resources in a metamorphic Holden schist and gneiss belt (Cu, Zn, low-grade, disseminated hot-springs deposit. Au, and Ag); (E) gold-bearing quartz veins resulting from regional metamorphism; (F) zoned ultramafic B. Hydrothermal-vein and limestone-replacement rocks containing pod-shaped deposits of chromium and deposits associated with igneous rocks platinum-group metals, or ultramafic rocks containing magmatic concentrations of nickel, cobalt, chromium, and platinum-group metals; and (G) placer-gold Base- and precious-metal hydrothermal veins tire deposits. Each of these deposit types is briefly common peripheral features associated with discussed below, and the field observations, porphyry-type deposits. They occur in thick volcanic interpretation of the geologic setting, geochemistry, piles of andesitic to rhyolitic composition associated mineralogy, gravity, magnetics, and mining activity with tensional or extensional regional tectonic stress data leading to the resource assessment are patterns. They generally form within several thousrnd summarized in the accompanying tables (3-6). feet of the surface and are spatially associated with centers of volcanic activity. Geochemical anomal'^s A. Hot-springs deposits commonly observed in stream sediments may inchMe arsenic, antimony, silver, gold, tellurium, lead, zr>c, Hot-springs deposits, noted primarily for their and copper. Heavy-mineral concentrates may contain large-volume, low-grade gold potential (Radtke and arsenopyrite, chalcopyrite, pyrite, galena, sphalerite, others. 1980; Silberman, 1982) occur in young, scheelite, cinnabar, native gold, and various sulfosalt uneroded belts of volcanic rocks that are dominantly minerals, such as tetrahedrite and tennantite. dacite and andesite, with lesser amounts of rhyodacite Widespread evidence of sericitic, kaolinitic, and rhyolite. Shallow felsic intrusions appear to carbonatic, and propylitic alteration may be present. provide the heat, and the vent areas are characterized Thin envelopes of potassic alteration in wall rock n^ay by extensive hydrothermal alteration, particularly also occur along veins where chalcopyrite is 12 121°30' 121°00' 120°30' NORTH CASCADES \ JORDAN LAKES AND NATIONAL CYCLON LAKE PLUTONS

BUCKINDY IPLUTON Mount Buckindy

Su/phur Hot Springs

SULPHUR MTN LUTO v ijflBimXN A^ \Springsv A-

Approximate boundary of Giacier Peak Wilderness

Approximate boundary of areas of recommended 06031A wilderness addition \

10 MILES _J

EXPLANATION

Volcanic and volcaniclastic rock (Quaternary) Geologic terrane having moderate mineral resource potential Granitic rock and porphyry (Miocene) Geologic terrane having low mineral resource potential Granitic rock and granitic gneiss (Tertiary and Cretaceous)

Foliated diorite and gabbro, schist and gneiss (Pre-Tertiary)

Figure 3. Map showing locations and mineral resource assessment of areas discussed under the hot-springs model (see table 3). 13 Table 3. Summary of data for the hot-springs-deposit model [Field observations: + 4 feature observed; -, feature not present; ?, field'observations not fliade or inconclusive. Geophysical anomalies: H, high; L, low; ?, no indication. Potential for occurrence of mineral resources: L, low; M, moderate. Minerals: Py, pyrite; Sch, scheelite; Ti-m, titanium minerals; Bar, barite. NA, not available!

Round Lake Gamma Ridge- Kennedy Sulphur Recognition Goff Prospect volcanics rocks Gamma Hot Springs Hot Springs Hot Springs criteria (area A-l) (area A-2) (area A-3) (area A-4) (area A-5)

1. Regional geologic setting A. Intermediate to felsic volcanic rocks B. Presence of caldera or volcanic center containing intrusive phases C. Presence of high-angle normal faulting 2. Geologic environment A. Dacitic to rhyolitic volcanics and volcaniclastic rocks B. Shallow level of erosion C. Local structural fracturing D. Primary porosity/ permeability in rocks E. Hydrothermal fracturing/ brecciation F. Alteration Limonite Limonite Propylitic argillic G. Silicification H. Stockworks/veinlets I. Presence of active hot springs J. Presence of travertine 3. Geochemistry NA' i . A. Anomalous anions or NA NA , Zn, Mo NA cations in hot- NA2 NA2 2CT springs waters HC03-, CT , S0d= , C NA NA 3H2s, cr HC03", CT, H?S Zn, Hg B. Anomalous elements in Mo, Cu, Pb, Au, Pb Au, Ag None Mo, Ni stream sediments Co, Mn, Zn, Ag, Au

C. Anomalous acid-soluble As, Cu, Pb, Cu, Co, Ni, Mo, Mn, Ni , None Cu, Zn, Co, elements in stream Zn, Ag, P, Co, Mn, Ba, W, Zn, Co, W, As, Ni , Mn, Ba, sediments Ni, Mn, Ba As, Ti, Nb Sr, Ti , Nb Sr, Cr

D. Anomalous elements in Mo, Cu, Pb, Cu, Pb, Hg, Cu, Pb, Hg, Mn, Cu, Co Mn, Co, Ba panned concentrates Hg, Ag, Co, Ag, As, Co, As, Ag, Co, W, Sn, Bi, Ra, B, Bi, W Ba Ba, B

E. Mineralogy of heavy- Py, Sch Py, Ti-m Py, Bar NA NA mineral concentrates

F. Anomalous halo elements Ba, Ni(?) Ba Mn, Ba in rocks

G. Anomalous commodity Ag, Cu, Mo, Cu, Ag Mo, Ag elements in rocks Pb, Sn, Zn

4. Geophysics

A. Magnetic indication H H ? H ?

B. Gravity indication ? ? L ? ?

5. Mining activity summary

A. Known deposits None None None None None

B. Mineral occurrences or Goff("#92, SG-33), None None None None zones containing Cu , Ag , Au possible undiscovered resources

C. Number of prospects, 9 0 000 workings, and the like (not including 5A)

6. Resource assessment L L MIL

Data this study. 2 Data from Tabor and Crowder (1969). Mariner and others (1982). if Stotelmeyer and others (in press). 5Grant (1982). abundant. Brecciation is a common feature. Ore Carmen deposit, which is either a tactite or minerals may be either disseminated or vein deposits limestone-replacement deposit, and the Copper King in vugs, fractures, and open spaces (Barton, 198 Z; properties are along the same structure and have Berger, 198Z; Berger and Eimon, 1983). The ores of possible undiscovered base- and precious-metal the Monte Cristo district southwest of the study area resources. The Goericke property on Company Creek are an excellent example of this type of hydrothermal has possible undiscovered resources. vein deposit (Spurr, 1901; Church and others, 1983c). Area B-4 has a high potential for the occurrence High-grade, localized deposits may also result of base- and precious-metal resources. A major when hydrothermal solutions react with limestone or sulfide vein at the Pioneer patented claims is in 'area marble to form replacement deposits. Although no 06031G. Demonstrated and inferred resources are mappable limestone units (1:100,000 scale) are present 734,000 tons of silver-lead-zinc ore containing 6.46 oz in the study area, local geology also makes this type of silver/ton, 6.4 percent lead, 6.5 percent zinc, 0.5Z deposit a feasible variant of the hydrothermal-vein percent copper, and 0.015 oz gold/ton. The deposit is deposit model; the Carmen property (table Z, no. 35) adjacent to a large breccia pipe at the Triplets (Tabor, is a possible example of a hydrothermal limestone- 1963). The Silver Queen prospect, just outside the replacement deposit. The data for areas having boundary of the recommended wilderness addition, is a potential for base- and precious-metal vein deposits limestone-replacement deposit in Cascade River Schist are summarized in table 4; areas are shown in figure 4 of Misch (1966). It has an estimated 69 tons of (areas B-l to B-8). mineralized rock in high-grade pods, containing 4.8 oz Area B-l has a high potential for the occurrence silver/ton, 5.0 percent lead, 2.0 percent zinc, and some of precious-metal resources and contains three copper, gold, and cadmium (see table 1). An adjacent deposits having identified resources. The Deerfly area, B-5, has similar geochemical, geophysical, and prospect, a disseminated-silver deposit probably geologic features (table 4) and has a moderate associated with the Glacier Peak hydrothermal system, potential for the occurrence of base- and has demonstrated resources of 174,000 tons containing precious-metal resources in hydrothermal veins. 0.75 oz silver/ton, with some gold and copper. The Area B-6 is on the Glacier Peak transverse shear deposit is in pervasively sheared granodiorite belt of Grant (1969) near a granitic plug. This system containing closely spaced quartz veins and showing has produced an intense red color anomaly, reflecting sericitic alteration. Pyrite, arsenopyrite, the surrounding pyritic shell, and is characterized by chalcopyrite, pyrrhotite, and tourmaline are abundant; isolated geochemical anomalies and a favorable the rock also contains minor galena and sphalerite. magnetic signature. No exploration work has been The Crown Point mine has demonstrated resources of done in the area. On the basis of this study, area B-6 1,300 tons containing 2.9 oz silver/ton, 2.6 percent is assigned a low potential for the occurrence of base- copper, 0.39 percent lead, and 0.7Z percent zinc. This metal resources in hydrothermal veins. deposit is in shears and small veins in a large quartz Area B-7, located mainly in area 06031A, south pod in weakly altered granodiorite of the Cloudy Pass of the wilderness, is defined largely by geochemical pluton. The mHe produced 10-12 tons of molybdenum anomalies associated with volcanic plugs. Company ore (1901-02), and some museum specimens of assay records from an adit in area B-7 indicate a silver molybdenite were removed, but the deposit is small. vein having 13.85 oz silver/ton and 8.3 percent copper The Victor prospect, 1,800 ft north of the Crown Point (Stotelmeyer and others, 1982), but there are no mine, is probably part of the same hydrothermal indications that this is anything other than a localized system. Stringers of sulfides occur in altered high-grade occurrence. Based on this study, area B-7 granodiorite; galena, sphalerite, chalcopyrite, and is also assigned a low potential for the occurrence of bornite were identified, and ruby silver may be precious-metal resources. present. The Ideal prospect has demonstrated The Cougar-Mountain Lion prospect (B-8), resources of 34,000 tons containing 1.42 oz silver/ southeast of, but immediately adjacent to, the study ton. It is on a quartz vein in orthogneiss cut by area, is associated with a rhyodacite plug containing numerous lamprophyre dikes containing pyrite. disseminated sulfides and is classified as having a low Geologic inference suggests that the area of the Ideal potential for the occurrence of base- and precious- prospect is underlain by the Cloudy Pass batholith. metal resources in hydrothermal veins. Area B-8 Area B-2, which includes the Esmeralda and extends into the wilderness. Peacock claims along Phelps Ridge, has a high potential for the occurrence of base- and C. Porphyry deposits precious-metal resources. The presence of scorodite (a hydrous iron arsenate) and abundant amorphous Porphyry deposits, that is, disseminated deposits silica suggests shallow deposition of ore. Area B-2, formed by convecting hydrothermal systems in the Red Mountain, consists of extensively pyritized and rocks surrounding an intrusive, are generally classified altered gneiss overlying the Cloudy Pass pluton (Grant, according to the geologic conditions of emplacement. 1982). It has a pronounced red color anomaly and Both the volcanic- and plutonic-type porphyry deposits widespread geochemical anomalies. are common in the Canadian cordillera (Brown, ed., Area B-3, north of area B-l, in the Stehekin 1976). Hollister (1979) has briefly summarized the mining district, has a high potential for the occurrence distribution of known porphyry-type deposits from the of base- and precious-metal resources in hydrothermal Canadian cordillera south into the Cascade Range of veins and in limestone-replacement deposits in Washington and Oregon. Both copper- and pre-Tertiary gneisses. Widespread geochemical molybdenum-rich systems occur in the study area. anomalies reflect the distribution of sulfides along Porphyry deposits are associated with tensional shears in the roof rocks over the Cloudy Pass calc-alkaline igneous intrusive belts that passively pluton or along nearby structural features. The intrude regional zones of structural Weakness caused 16 121°30' 121°00' 120°30' (NORTH CASCADES \ JORDAN LAKES neer AND Triplets NATIONAL CYCLON LAKE {Silver Queen. CAS6A&E PLUTONS

CHAVAL PLUTON

BUCKINDY MAP LOCATION ^PLUTON Mount Buckindy

SULPHUR MTN PLUTON

Monte Cristo area Approximate boundary of Glacier Peak Wilderness

Approximate boundary of areas of recommended

10 MILES I

EXPLANATION

Geologic terrane having high mineral Volcanic and volcaniclastic rock (Quaternary) resource potential Granitic rock and porphyry (Miocene) Geologic terrane having moderate mineral resource potential Granitic rock and granitic gneiss (Tertiary and Geologic terrane having low mineral Cretaceous) resource potential X Mineral prospect Foliated diorite and gabbro, schist and gneiss 5? Mine (Pre-Tertiary)

Figure 4. Map showing locations and mineral resource assessment of areas discussed under the base- and precious-metal-vein model (see table 4). 17 Table 4. Summary of data for base- and precious-metal hydrpthermal-vein-deposit model [Field observations: + , feature observed; -, feature not present; ?, field observations not made or inconclusive. Geophysical anomalies: H, high; L, low; RLG, regional linear gradient; ?, no indication. Potential for occurrence of mineral resources: L, low; M, moderate; H, high. Minerals: Sch, scheelite; Tour, tourmaline; Py, pyrite; Ti-m, titanium minerals; Cpy, chalcopyrlte; Bar, barite; Gal, galena]

Recognition criteria Area B-l Area B-2 Area B-3 Area B-4 Area B-5 Area B-6 Area B-7 Area B-8

1. Regional geologic setting

A. Calc-alkaline igneous belt* + + + - + + +

2. Geologic environment A. Oacitic/calc-alkaline - + + _ _ + + + volcanics

B. Associated with intrusive + + + + _ + + + center

C. Presence of dike swarms * + ?++?+-

D. Shallow-level intrusion + + + + ? + + " +

E. Tensional fracturing + + +++++-

F, Primary porosity/permeability - - - -- _.+

G. Presence of intrusive breccia - + +++.-+ (breccia pipe or explosion breccia)

H. Alteration Phyllic, Phyllic, Limonite Quartz veining Pyrite/ Propylitic Limonite Pyrite/ sericitic sericitic limonite limonite

I, Disseminated pyrite * + *

J. Vein filling + + + , ,

3. Geochemistry

A. Anomalous elements in Mo, Pb, Zn, Mo, Cu, Pb, Mo, Zn, Au, Co Mo, Cu, Pb, Cu, Zn, Au, Au, Cu, Pb, Mo Mo, Cu, Pb, Pb, Zn, Ag, stream sediments Ag, Au, Co, Ag, As, Co, Zn, Ag, Au Ag, Co, Mn Co, Mn, Ag, An, Mn, Mo Mn, Ni Au, Sb Au, Zn

B. Anomalous acid-soluble Mo, Cu, Pb, Mo, Cu, Pb, Mo, Cu, Zn Cr, Cu, Pb, P, Mo, Cu, Cu, Zn, Nb, Co, Cu, Pb, Zn, Mo, Cu, Pb, elements in stream Zn, Co, Mn, Zn, Co, Mn, Co, Mn Zn, Co, P, Sr, Zn, Co, Ba, As, Ni, W, Ba, Ag, Co, Ni, Zn, Mn sediments As, Ti As Ni, Mn, Ba Sr, Ni, Mn, Mo, Mn Mn Pb, As

C. Anomalous elements in panned Mo, Cu, Pb, Cu, Pb, Hg, Cu, Mo, Pb, Cu, Pb, Hg, Cu, Pb, Hg, Cu, Pb, Hg, Ag, Mo, Cu, Pb, Cu, Pb, Hg, concentrates Ag, As, Co, Sn, Nb, Ba, Hg, Co, W, Ag, As, Co, Ag, As, Co, As, W, Nb, Hg, Ag, Co, Ag, Co, Mo, Hg, W, Sn, B Bi, Ba, B W, Ba, B, Ba, B, W, Sn B W, Sn, Bi, Bi, Sn Bi , B, Ba Sn, Bi Ba, B

D. Mineralogy of heavy-mineral Sch, Tour, Sch, Py, Cpy, Py, Bar, Py, Gal, Py, Sch, Py, Ti-m Py, Sch Py, Ti-m concentrates Py, Ti-m Ti-m Sch, Ti-m, Sch, Ti-m Bar, Ti-m Tour

E. Anomalous halo elements Mn, B, Ba, B, Mn, As, Mn, Sb Ba, As, Sb, Mn, B, Ni , None Ba, Ni(?) None in rocks Bi, Cd, Zn, Sb Sb, Bi, Ba Mn, Cd As, Sb

F. Anomalous commodity elements Ag, Pb, Ag, Au, Pb, As, Ag, Au, Pb, Zn, Ag, Ag, Pb, Cu, Ag, As Ag, Cu, Mo, None in rocks As, Mo Zn, Cu, Mo, W Cu, Pb, W, Zn Cu, Mo Mo, Zn Pb, Sn, Zn 4. Geophysics

A. Magnetic indication L ? RLG H H L H H

B. Gravity indication L ? ? L ? L ? ? 5. Mining activity

A. Known deposits Ideal (^SS), Ag None None Pioneer ( #7, None None None None Deerfly ( 1 *46, Vl5), 2G-3Z), Pb, Ag, Ag Zn, Cu, Au Crown Pt. mine Silver Queen ( «5), ('#43, 2 G-6), Pb , Ag , Zn , Cu , Au, Ag, Cu, Mo Au, Cd

B. Mineral occurrences or Victor {'#44, 2 G-29), Peacock ('#57), Goericke ( 1 #32, Cascade ( 2G-30), None None Goff ( 1 #92, 2G-33), Cougar zones with possible . . , ... . -,, Ar r ,,, -,, . undiscovered resources Ag ' "* Zn Au, Ag, Cu, As G-ll),Cu,Ag Pb, Ag Cu, Ag, Au ( 1 #21), Esmeralda ( #56, Carmen ( #35), Epoch ( 2 G-31), Au, Zn, Cu G-5), Au, Ag, tactite-Cu, Pb, Pb, Ag Cu, As Zn, Ag Copper King ( #36 Cu, Co, Ag C. Number of prospects, 8 20 7 40096 workings, and the like (not including 5A)

6. Resource assessment H H H H M L L L

Stotelmeyer and others (in press).

2 Grant (1982). by crustal extension or strike-slip faulting. The minerals and sulfides. Poorly developed lead, zinc, igneous rocks of the volcanic-porphyry deposits have silver, and gold geochemical halos are evident. There generally intruded slightly older volcanic rocks is extensive metasomatic alteration adjacent to whereas the plutonic-porphyry deposits are found in veinlets, and pod-like, pegmatitic masses of quartz and complex batholithic terranes. Commonly, porphyry potassium feldspar accompany magnetite and sulfides, deposits are associated with breccia pipes and (or) dike analogous to the barren quartz core found in the swarms. Evidence of hydrothermal alteration is Glacier Peak deposit (Grant, 1969). Zoning patterns of widespread. The porphyry deposits may be associated alteration are not well defined. with a local gravity high. The principal mineral resources of thq study area The volcanic-porphyry deposit is generally are in porphyry-type deposits. The resources and characterized by argillic, phyllic, and propylitic reserves defined by subsurface drilling at the Glacier alteration halos; the potassic alteration is rarely Peak deposit (see tables 1 and 5; fig. 5, area C-l) exposed. Alteration of mafic minerals to magnetite constitute the most important known deposit. The may produce a magnetic high associated with the area around the Glacier Peak prospect has 1.9 billion deposit. Base- and precious-metal hydrothermal-vein tons of demonstrated resources containing 0.334 deposits are common peripheral associations. percent copper and O.OZ percent molybdenum; Stockwork may have developed in the volcanic edifice tungsten, gold, and some silver are probable or autobrecciation may indicate a shallow igneous coproducts. The area contains 17 patented claims. cupola. Good circulation in permeable rocks is needed The deposit is a late intrusive phase of the Cloudy Pass to form a deposit. Geochemical anomalies commonly pluton that has disseminations and veinlets of sulfide observed in stream sediments may include manganese, minerals. Many of the features described by Grant copper, molybdenum, lead, zinc, silver, and gold. (1969) as important elements in the plutonic-porphyry Heavy-mineral concentrates may contain tourmaline, deposit were intersected by Bear Creek Mining Co. gold, barite, molybdenite, galena, chalcopyrite, pyrite, drilling at the site of the main ore body. The bornite, scheelite, and sphalerite. Geochemical precious-metal deposit at the Deerfly prospect (B-l, anomalies from this medium may contain barium, tin, fig.4) and the geochemical anomalies in area C-Z tungsten, bismuth, and mercury, in addition to those constitute the precious-metal halo surrounding this elements anomalous in stream sediments. (See Grant, porphyry deposit. The potassic, sericitic, and chloritic 1969; Lowell and Guilbert, 1970; Brown, ed., 1976; (propylitic) zones, as mapped by Bear Creek Mining Pilcher and McDougall, 1976; Colley and Greenbaum, Co., close within the boundaries of area C-l. The axis 1980; Beane and Titley, 1981; Titley and Beane, 1981; of the deposit trends east-west and is marked by a Chaffee, 198Za, b; Cox, 198Z; Moss, 198Z; Cox, 1983). linear magnetic low within the Cloudy Pass magnetic The plutonic-porphyry deposits are characterized anomaly (Flanigan and others, 1983). The Fortress by propylitic and phyllic alteration peripheral to a Mountain, Copper Point, and Esmeralda properties also weakly developed potassic alteration zone surrounding have possible undiscovered resources (see table Z). the central, copper-rich ore zone. Veins of quartz, Area C-l (table 5) has a high potential for the sericite, and pyrite form an intensely developed occurrence of base-metal resources of copper, Stockwork; deposits formed in rock fractured solely by molybdenum, tungsten, and gold, and possible lead, regional tectonic stresses are generally low grade. zinc, and silver byproducts in porphyry deposits. Geochemical halos of base and precious metals are Area C-2, immediately west of C-l, has base- common, and evidence of a contact-hornfels zone may and precious-metal geochemical anomalies, but erosion be difficult to distinguish in a complex batholithic has cut deeply into the interior of the Cloudy Pass intrusion. Geochemical anomalies found in stream pluton, and no indications of mineralization were sediments may include manganese, copper, observed in the rocks. This area is analogous to the molybdenum, cobalt, lead, zinc, silver, gold, and barren metal halos surrounding the root zones of boron. Heavy-mineral concentrates commonly contain porphyries as discussed above (Burning and Bavis, chalcopyrite, pyrite, tourmaline, galena, sphalerite, 1978, p. 88) and has a low potential for the occurrence scheelite, and gold. Geochemical anomalies from of base- and precious-metal resources in porphyry concentrates may include tungsten, tin, arsenic, and deposits. barium in addition to those elements anomalous in the Area C-3 marks the axis of intrusion of the stream sediments. Hydrothermal alteration may cause Cloudy Pass pluton along the Entiat fault. At the replacement of magnetite by pyrite, resulting in the south end of area C-3, in area 06031B, the Royal association of a magnetic low with the deposit (see Bevelopment mine, a breccia pipe, has inferred Grant, 1969; Brown, 1976; Brown, ed., 1976; Pilcher resources of 8.5 million tons containing 0.4 percent and McDougall, 1976; Chaffee, 198Za, b; Cox, 198Z; copper and 0.9 oz silver/ton. Similar breccia pipes are Moss, 198Z). present at the north end of area C-3 at the Esmeralda One of the more important questions in and Peacock prospects (C-l). Area C-3 has a high evaluating the plutonic-porphyry deposits is the depth potential for the occurrence of base-metal resources of erosion. Burning and Davis (1978) examined the in breccia pipes or disseminated porphyry deposits. geological and geochemical expressions of the exposed Area C-4 is largely unexplored, but contains root zones of porphyry deposits and concluded that three deposits discussed earlier as having possible important characteristics of root zones are general undiscovered resources (see tables Z and 5). Only the absence of porphyritic texture in the intrusion, Goericke prospect has altered and mineralized rock absence of breccia pipes, lack of closely spaced typically associated with porphyry-copper deposits. fractures, absence of vugs in veinlets, and sparsity of Plugs and dikes of porphyritic quartz diorite and dikes. Chalcopyrite, pyrite, and molybdenite are granodiorite intrude the schist and gneiss (Grant, 198Z, present, but the chalcopyrite content decreases with p. 28). The regional linear gradient of the magnetic depth. Secondary magnetite commonly replaces mafic data suggests that the contact with the Cloudy Pass 20 121°30' 121°00' 120°30' iNORTH CASCADES \ JORDAN LAKES AND NATIONAL CYCLON LAKE PLUTONS

^BUCKINDY IPLUTON Mount Buckindy

31D I Development mine

Approximate boundary of Glacier Peak Wilderness

Approximate boundary of *' C-71

10 MILES I

EXPLANATION C-1 Geologic terrane having high mineral Volcanic and volcaniclastic rock (Quaternary) resource potential C-7 Granitic rock and porphyry (Miocene) Geologic terrane having moderate mineral o resource potential Granitic rock and granitic gneiss (tertiary and Geologic terrane having low mineral Cretaceous) resource potential X Mineral prospect Foliated diprite and gabbro, schist and gneiss (Pre-Tertiary) Mine Contact Fault Figure 5. Map showing locations and mineral resource assessment of areas discussed under the porphyry model (see table 5). 21 Table S.--Summary of data for the porphyry copper-molybdenum-deposit model [Field observations: +, feature observed; -, feature not present; ?, field observations not made or Inconclusive. Geophysical anomalies: H, high; L, low; RLG, regional linear gradient; ?, no Indication. Potential for occurrence of mineral resources: L, low, M, moderate; H, high. Minerals: Moly, molybdenum; Py, pyrlte; Seh, scheellte; Bar, berlte; Cpy, chalcopyrlte; T1-m, titanium minerals; Tour, tourmaline; Gal, galena. NA, not available]

Plutonic porphyry type Volcanic- porphyry type Area C-l Area C-2 Area C-3 Area C-4 Area C-5 Area C-fi Area C-7 Recognition Glacier Peak Fortress Mtn. Esmeral da- Royal Development Mount Bucklndy Milt Creek Triplets West Red Mtn. Goff Prospect crlterta deposit Copper Pt. mine

1. Regional geologic setting A. Calc-alkaline * * * igneous belt Q features 2. Geologic environment

A. Quartz-dlorite/grano- t + t dlorlte or inter­ mediate volcanic rocks B. Level of erosion intermediate intermediate shallow deep shallow shallow Intermediate shallow shallow shallow shallow C. Age of Igneous event 20 m.y.(?) M1ocene(?) 20 m.y.(?) 20 m.y.(?) 20m.y.(?) 20 m.y.(?) 14 m.y.(?) M1ocene(?) 18 m.y.(?) 'M1ocene(7) Miocenef?)

D. Porphyrltic texture + - + 7 + + + + + E. Dike swarms + + + + + + + ? 7 F. Igneous cupola + + + 7 * ro H> Primary permeability/ - - - porosity

breccia (breccia pipe or explosion breccia)

K,. Alteration Propylitic/ Propylitic/ Phyllic/ none Propylitic/ Chlorlte/ Phyllic/ Propylitic/ Limonite Propylitic Limonlte sericitic/ sericitic/ sericitic observed phyllic seridte sericitic phyllic/ potassic potassic sericitic

L,. Pyrite envelope + 7 - M,. Barren quartz core + 7 ? 7777 7 7 ? ?

3. Geochemistry

stream sediments Ag, Zn, Au Au Au Au Ag, Au, Co Pb, Ag, Au Zn, Ag, Au Mo Zn, Ag, Au, Co, Mn

B . Anomalous acid-soluble As, Mo, Cu, Mo, Cu, As Mo, Cu, Pb, Mo, Cu, Pb, Cu, Zn, As, Mo, Cu, Zn, Mo, Cu, Zn, As, Mo, Cu, P, Mo, Cu, Nb, Cu, Zn, Cu, Pb, Zn, metals in stream Zn, TI, Pb, Co, As, Nb, Zn, Ag, T1 , Sr Co, Mn Co, Pb, As, Pb, Zn, Ba , Pb, Zn, As, Co, Ni , W, Ag, Co, Ni , sediments Mn, Ba, Nb T1 As, Sr, T1 Ti, Nb Co, Ni, Mn, Ba, Ni, Co, Mo, Mn, As, Ba Mn Sr, Cr Mn, Sr

C . Anomalous metals in Mo, Cu, Pb, Cu, As, Co, Cu, Pb, Ag, Mo, Cu, Pb, Co, Mn, Cu, Cu, Co, Mn, Mo, Cu, Pb, Mo, Cu, Pb, Mo, Cu, Pb, Cu, Pb, Hg, Mo, Cu, Pb, W, Sn, Bi, B1, Ra, B B, W Co, W, Sn, B, BI Ag, W, Sn, W, Sn, B1 , Co, W, Sn, Nb, B W, Sn, B1 , Hg, B, Ba Nb, Ba, B1 Bi, Nb Nb, Ba, B Bi , Ba Ba ,. B D,. Mineralogy of heavy- Moly, Py, Sch, Sch, Tour, Ti-m Sch, Py, T1-m Py, Ti-m NA Cpy, Py, Bar, Moly, Py, Sch, Py, Sch, T1-m Moly, Cpy, Py, T1-m Py, Sch mineral Bar, Cpy, Ti-m, Sch, T1-m Ti-m, Tour Gal, Py, concentrates Tour Sch, T1-m E. Anomalous halo As, Ag, B, As, Hn, Ag, B, Hn. As, None As, Ba, B1 , As. B, Ba, B, Hn, As, Hn, As, Ba, Mn, As, B, Ag, As Ba , Pb, Zn, elements in rocks Ba, Pb, Sb, B Sb, B1, Ba Cd, Pb, Sb, Sb, Zn B1, Zn Pb Ba, 81 , Sb Ag Hn, Zn Zn F. Anomalous commodity Cu, Co, B1, Cu, Mo, Pb Cu, Mo, Pb, None Ag, Au, Cu, Au, Cu, Pb, Cu, Mo, Pb, Sn Ag, Cu, Mo, Ag, Co, Cu, None Cu, Mo, Sn elements In rocks Au, Ag, Mo, Ag, Au, Zn, H Mo, Sn, H Zn Zn Mo, Pb, Zn Sn, W, Pb 4. Geophysics A. Magnetic indication local L on H H H local L on H ? RLG H H H L H

B. Gravity indication L L L L T H ? L L L ? 5. Mining activity summary A. Known deposits and Glacier Peak (V4B. 2G-1), Cu, Mo, Ag, Au, W . None Royal Development None Pioneer ('*7, 2G-32), Pb, Ag, Zn, Cu, Au None None None commodities Deerfly ('146, 2 G-15 mine ('164), Silver Oueen ( 1 I5), Pb, Ag, Zn, Cu, Au, Co Crown Pt. mine (**43 , z G-6), Au, Ag, Cu, Pb, Zn, Mo Cu, Ag, W

B. Mineral occurrences or Fortress Mtn. ( 1 K1, 2 G-3). Cu- None Peacock (*#57), Goericke( 1 l32, Mount Buckindy ( 1 I2, 2 G-2), Cu, Mo.Ag--- - None None Goff zones containing Ag, Pb, Zn Cascade ( Z G-30) , Pb, Ag - - ( l *92, possible widespread Victor ( l !44,2G-29), Ag, Au, Cu, As ZG-]1), Cu. Ag resources Copper Pt. ('fSS^G- 24), Au, Ag, Cu, Pb, Zn .... Carmen ( 1 I35), Epoch ( Z G-31), Pb, Ag- 2 G-33), Esmeralda ('ise.'G-S ), Cu, Au. Ag, As Pb, Zn, Ag, Cu, Cd Cu, Ag, Au Copper King ( 1 I216), Cu, Co, Ag C. Number of prospects, 25 25 25 0 6 6 55 509 workings, and the like (not including 6A) D. Drilling activity At least 75 drill Three drill holes, None None Many drill holes, None Five drill holes. None None None None holes with more 363 ft of core more than 10,000 ft 2,280 ft of core ro than 50,000 ft of (Grant, 1982) of core (Grant, 19B2) U) core (Grant, 19B2) E. Resource assessment H H H L H M MM M L M

'stotelmeyer and others (in press). z Grant (19B2). pluton is nearby (Flanigan and others, 1983). This area by Kinkel and others, 1956, of the stockwork exposed has a moderate potential for the occurrence of at the Mammoth mine in the West Shasta district of base-metal resources in disseminated porphyry northern California). Chlorite and silica and sericitic deposits. alteration zones may surround massive-sulfide Area C-5, in the vicinity of Mount Buckindy, has deposits, and then a larger, more easily detected, a moderate potential for the occurrence of copper and geochemical anomaly may result (Sangster, 1972; Doe, molybdenum resources in porphyry deposits. Wide­ 1982). Geochemical anomalies, however, are generally spread geochemical anomalies and locally altered rock subtle; zinc, barium, and either copper or silver may are present; two breccia pipes are exposed on Mount be found in the stream sediments. Heavy-mineral Buckindy. The best intercepts from five drill holes in concentrates may contain barite, pyrite, pyrrhotite an area near the summit of Mount Buckindy averaged (found in the magnetic separate), and, rarely, chalco- 0.34 percent copper and 0.13 percent molybdenum. pyrite and sphalerite. Geochemical anomalies Widespread geochemical anomalies along strike to the detected in heavy-mineral concentrates may include northeast in Milt Creek are described by Grant (1982, cobalt, mercury, and gold in addition to those elements p. Z4-Z5) as fracture-controlled mineralization. anomalous in stream sediments. Generally, geophysi­ Propylitic alteration is widespread, numerous porphy- cal methods are useful in prospecting for massive- ritic dikes containing sulfides occur throughout the sulfide deposits because they are characterized by area outlined, as well as to the south of it, and vugs of both a magnetic and a gravity contrast; electromag­ quartz crystals occur in hydrothermal veins in the netic methods have also been successful. schist. This area has a moderate potential for the The pre-Tertiary metamorphic rocks in the east- occurrence of base-metal resources in disseminated central part of the study area are part of a belt of late porphyry deposits. The Triplets, a large breccia pipe Paleozoic oceanic sediments and island-arc volcanic structure located along strike just northeast of the rocks that are now preserved in thrust sheets north of study area, may also contain resources of base metals the study area (Misch, 1966, pi. 1). This series of rocks in a deposit analogous to that found at the Royal was mapped by Cater and Crowder (1967) and Cater Development mine (see area C-3, fig. 5). and Wright (1967) as the younger gneissic rocks of the Area C-6 contains a granitic plug that intruded Holden area. Detailed mapping (DuBois, 1954) of the gneiss. A pyritic halo weathers to form a pronounced area near the Holden mine, done in conjunction with red color anomaly. Geochemical anomalies surround­ company geologists, indicated abundant amphibolite ing the plug indicate possible base-metal mineraliza­ and calc-silicate lenses. A brief summary of the tion (see discussion of area B-6). A weak propylitic- geology of the Holden mine was presented by alteration halo is present. Little exploration work has Youngberg and Wilson (1952). Amphibolites and meta- been done. We have classified the area as one of low volcanic rocks are more abundant in the geologic potential for the occurrence of base-metal resources section near the Holden mine than to the north. in a porphyry deposit, although further work may prove ' Mattinson (1972, p. 3773) gave a late Paleozoic age of that the area warrants a higher resource classification. 265±15 m.y. for the metavolcanic rocks. Area C-7, the Goff prospect, surrounds a Ter­ Ores of the Holden mine are stratabound and tiary plug of dacitic rock having a strong gravity zoned; gold values parallel copper (chalcopyrite) high. Geochemical anomalies are widespread, but they content, and silver values peripheral to the chalco­ are particularity strong along an east-west fracture pyrite zones show a crude correlation with zones of zone near the wilderness boundary. This area has a iron-rich sphalerite and minor galena (Frank Ebbutt, moderate potential for the occurrence of base-metal unpub. data, 1938; Youngberg and Wilson, 1952). resources in a disseminated porphyry deposit. Magnetite is common; molybdenite and radioactive Many less well defined geochemical anomalies of minerals are rare. DuBois (1954) described a base metals occur throughout the study area, but conformable lens of anhydrite and numerous lime- existing data are not sufficient to warrant discussion silicate lenses that parallel the layering of the of the mineral potential of these areas (see Church and amphibolite in the Holden mine. We interpret these others, 1982; Grant, 1982; Stotelmeyer and others, in lenses as volcanic-exhalite layers intercalated with press). carbonate sediments deposited on the flanks of a submarine volcanic center. These characteristics (see D. Volcanogenic massive-sulfide deposits table 6) suggest that the deposit at the Holden mine is a massive sulfide of late Paleozoic age that was sub­ Volcanogenic massive sulfides, predominately sequently metamorphosed to amphibolite grade (Nold, pyrite or pyrrhotite deposits with associated chalco- 1981). Sulfide stringers indicative of Volcanogenic pyrite, sphalerite, and galena, form in belts of massive-sulfide deposits also occur to the north at the submarine volcanic rocks. Gold and silver are Mary Green deposit (see table 2), where workings commonly substantial coproducts (Singer and others, expose a small pyrrhotite-rich zone. Grant (1982) 1982). Features of Volcanogenic massive-sulfide states that these rocks can also be traced northwest deposits are described by Franklin and others (1981). into the Company Creek drainage basin (see the In the geologic environment where island arcs occur discussion of the Goericke prospect in the previous along continental margins, basalt and lesser amounts section). Studies of the Holden mine and tailings of andesite and dacite are interbedded with clastic indicate resources in both (see table 1). Exploratory deposits, tuffs, ferruginous cherts, and carbonate drilling during the late 1950's failed to prove additional sediments. The sulfide deposits are stratabound, and ore reserves at depth. Recovery of precious metals mineralogical banding results from primary deposition and zinc from the mill tailings is not cost effective at of sulfides on the sea floor. Hydrothermal alteration this time. is largely confined to the small feeder zone, resembl­ The Holden belt (area D-l, fig. 6) is defined ing a stockwork, below the deposit (see the description largely on the basis of geochemical anomalies and 24 Table 6. Summary of data for the volcanogenlc masslve-sulfide-deposit model [Field observations: +, feature observed; ?, field observations not made or Inconclusive. Geophysical anomalies: K, high; ?, no Indication. Potential for occurrence of mineral resources: M, moderate. Minerals: Py, pyrlte; Sen, scheelite; T1-m, titanium minerals; Tour, tourmaline]

Recognition Hoi den belt criteria (area D-l)

1. Regional geologic setting A. Island-arc setting

2. Geologic environment

A. Basalt>fel site

B. Calcarous sediments C. Ultramaflc associations

D. Exhalative layers

E. Iron-rich chert layers F. Conformable, tabular sulfide strata

G. Gossans

H. Alteration (sericite schist)

3. Geochemistry

A. Anomalous metals In stream Zn, Mo, Au, N1 sediments

B. Anomalous acid-soluble Nb, Mo, Cu, Zn, Co, metals 1n stream sediments Sr, Ni, Mn, T1

C. Anomalous metals In panned Cu, Mo, Mn, Ba, Sn, concentrates W, B

D. Mineralogy of heavy-mineral Py, Sch, T1-m, Tour concentrates

E. Anomalous halo elements Ba, Zn, Co, Cu in rocks

F. Anomalous commodity Ag, Au, Zn, Pb, elements 1n rocks Mo, Cu

4. Geophysics A. Magnetic Indication

B. Gravity Indication

5. Mining activity summary

A. Known deposits Holden mine ( l#23,2G-Holden mine zone), Cu, Au, Ag, Zn

B. Mineral occurrences or Mary Green ( l#29,2G-16), zones containing possible Cu, Ag undiscovered resources

C. Number of prospects, workings, and the like (excluding 5A)

D. Resource assessment

Stotelmeyer and others (in press).

Grant (1982). 25 geologic evidence. The outcrop pattern of the Holden F. Igneous cumulate deposits schist and gneiss belt is roughly coincident with a regional zinc anomaly and sporadic gold, nickel, and Layered ultramafic complexes are sources of molybdenum anomalies. However, these geochemical nickel, cobalt, chromium, and platinum-group metals. signatures may reflect, in part, Tertiary events along Nickel sulfides may be deposited near the base of the Glacier Peak transverse structure of Grant layered mafic bodies (Foose, 1982). Stratiform (1969). Dikes of Tertiary(?) granodiorite porphyry chromite lenses also are common, for example, in the occur in the Holden mine and on the ridge near the Stillwater Complex in Montana, where chromite pods Mary Green prospect. A strong geochemical anomaly occur in the lower third of layered igneous complexes occurs immediately south of the Holden mine in the (Jackson, 1968; Lipin and Page, 1982). Platinum-group headwaters of the Entiat River (Church and others, metals may occur with chromite (McLaren and 1983a, b) and is associated with Tertiary igneous DeVilliers, 1982), or platinum-rich zones may also activity. More detailed studies are needed to locate accumulate in the upper part of layered igneous concealed deposits in the belt and to map the felsic complexes (Todd and others, 1982). and mafic volcanic units in the younger gneisses of the Two mafic igneous rock units occur in the study Holden belt. Area D-l has a moderate potential for area. The Riddle Peaks pluton (F-l, fig. 6), north of the occurrence of copper, zinc, gold, and silver Holden, is a hornblende gabbro. No ultramafic resources in volcanogenic massive-sulfide deposits, on sequences are exposed. Reconnaissance geochemical the basis of our current geologic data. studies of samples from this body (R. R. Carlson and E. F. Cooley, unpub. data, 1982) indicated no E. Gold-bearing quartz-vein deposits in metamorphic detectable platinum-group metals. Detailed mapping host rocks and geochemical studies necessary to delineate possible platinum-group metal deposits in the pluton Gold-bearing quartz veins are a common occur­ are outside the scope of this study. The body is rence in greenstone belts of folded and metamorphosed associated with a pronounced magnetic anomaly continental margins such as the Abitibi belt of Canada (Flanigan and others, 1983). Assessment of possible (Boyle, 1979; Fryer and others, 1979) and the mother mineralized rock at depth by drilling was beyond the lode of the Sierra Nevada (Knopf, 1929). Quartz veins scope of this study. The area F-l is assigned a low are associated with fractures or faults in the rocks. potential for the occurrence of nickel, cobalt, These deposits have anomalous gold, silver, arsenic, chromium, and platinum-group metal resources in antimony, copper, and, locally, chromium signatures in magmatic segregations of mafic layered complexes. stream sediments (Bohlke, 1982). Heavy-mineral con­ Small bodies of ultramafic rocks are found in the centrates may include gold, cinnabar, arsenopyrite, central schist belt; geochemical studies indicate galena, sphalerite, stibnite, and sulfosalts. The anomalous chromium, cobalt, and nickel in drainage chromium-rich micas occur in association with carbon­ basins confined either to the schist belt or in drainage ates, commonly with dolomite, in this environment. basins along the Straight Creek fault west of the study Mercury, lead, zinc, and copper may occur as geo­ area. Most of the ultramafic bodies are only tens to chemical anomalies in the heavy-mineral concentrates hundreds of feet long; the largest bodies of ultramafic as well as those elements anomalous in the stream rock found in the area are on Spire Point (Grant, 1966), sediments. north of Glacier Peak (F-2, fig. 6), and along the White The general geologic indications for the presence River, south of the study area (Ford and others, in of gold-bearing quartz veins have not been observed in press). Because of the small size of the ultramafic the study area. However, area E-l (see fig. 6), defined bodies and their discontinuous nature, the area of the by the Chaval pluton in the northwestern part of the central schist belt has a low potential for the occur­ study area, contains the correct geochemical signature rence of nickel, cobalt, chromium, and platinum-group for this type of deposit. Alternatively, it also may be metal resources in pod-shaped deposits. classified as a hydro thermal-vein deposit that should be considered under section B. The pluton is dioritic G. Placer deposits to tonalitic in composition (A. B. Ford, unpub. data, 1982; Ford and others, 1983) and has been meta­ Placer deposits are possible where gold, morphosed. Gold anomalies occur in stream basins platinum, or heavy minerals such as garnet can be containing large quartz clasts, but the source veins concentrated by hydraulic means in streams. No were not found in outcrop. We have classified the evidence for gold placers was found in the study area outcrop area of the Chaval pluton as an area of low during either the geochemical reconnaissance or during potential for the occurrence of gold resources in specific studies for gold placers (Stotelmeyer and hydrothermal quartz veins. others, in press). The Railroad Creek drainage basin, Other areas of metamorphosed mafic volcanic below the Holden mine (see fig. 6), empties into Lake rocks in the study area, namely the Holden area Chelan before any suitable change of stream gradient discussed in the previous section, are not probable is encountered, and the area near the Glacier Peak areas where this model would be applicable because of deposit drains directly into the Suiattle River where a the high metamorphic rank. Free gold, however, was placer deposit would be difficult to find and work. separated from quartz-rich pods in the migmatitic Therefore, the study area has a low potential for the Skagit Gneiss east of the Holden mine (see fig. 6), occurrence of placer-gold resources. indicating that metamorphic concentration of gold may make this terrane a good source for gold in placer Potential for nonmetallic resources deposits. Nonmetallic commodities examined during this study include pumice and cinder, marble, garnet, and, 26 121°30' 121°00' 120°30' [NORTH CASCADES \ JORDAN LAKES AND

UCKINDY PLUTON Mount Buck!

Approximate boundary of Glacier Peak Wilderness

Approximate boundary of areas... of recommended. .v v 06031A wilderness addition V

10 MILES

EXPLANATION D-1 Geologic terrane having moderate mineral Volcanic and volcaniclastic rock (Quaternary) resource potential E-1 Granitic rock and porphyry (Miocene) jic terrane having low mineral resource potential Granitic rock and granitic gneiss (Tertiary and K Mine Cretaceous) X Mineral prospect Foliated diorite and gabbro, schist and gneiss (Pre-Tertiary)

Fault Figure 6. Map showing locations and mineral resource assessment of areas discussed under the volcanogenic massive-sulfide model (D, see table 6), the met am orphic-hosted, gold-bearing quartz -vein model (E), the igneous- cumulate model (F), and the placer model (G). 27 Table 7. Locations of nonmetalllc resources 1n and near the Glacier Peak Wilderness and adjacent areas, Chelan, Skaglt, and Snohomlsh Counties, Washington [Leaders ( ) Indicate that deposit is too widespread to be shown on map by number]

o No. Tonnage Resource on Property Type (except where classification Commodi ty Area map noted)

94 White Chuck cinder Pyroclastic 24 million Indicated; subecononric Volcanic Wilderness cone (cubic yards) cinders

Pumice deposits Py roc las tic Not available Numerous deposits, some Pumice Wilderness accumulations of which have had production, in upper Chiwawa and Entiat River basins 67 Chiwawa River pumice Pyroclastic 5.2 million Inferred; marginal Pumice 06031D (study area only) (cu yd) reserve 99 Circle Peak - Marblelzed 100 million Inferred; subeconomic Limestone adjoins area Meadow Mountain limestone 06031G 98 Lime Mountain Marble 400 million Inferred; subeconomic Limestone adjoins area 06031G 96 Garnet Creek - Garnet 2,000 Inferred; marginal Garnet adjoins area Ruby Creek (two pi acer reserve 06031G adjacent deposits)

^Numbers correspond to locations on accompanying map, MF-1652-A. 'U.S. Bureau of Mines and U.S. Geological Survey (1980).

28 121°30' 121°00' 120°30' NORTH CASCADES \ JORDAN LAKES AND NATIONAL CYCLON LAKE PLUTONS

Marble X 06031G

Kennedy Hot Springs

Approximate boundary of Glacier Peak Wilderness

Approximate boundary of--y areas of recommended '/, wilderness addition

10 MILES _J

EXPLANATION

X Mineral prospect Volcanic and volcaniclastic rock (Quaternary)

X Quarry Granitic rock and porphyry (Miocene) Hot Springs Granitic rock and granitic gneiss (Tertiary and Cretaceous)

Foliated diorite and gabbro, schist and gneiss (Pre-Tertiary)

Figure 7. Map showing locations of nonmetallic commodities (see table 7). 29 as possible byproducts of the mill tailings at the hot-spring activity. A low potential for geothermal Holden mine, pyrite and silica. Other nonmetallic resources exists near the north and west sides of resources not examined might include sand and gravel, Glacier Peak in the Gamma Hot Springs area. talc, soapstone, kyanite, and feldspar. Identified Detailed hydrologic and heat-flow investigations and resources for several of these commodities are given drilling would be required for a comprehensive in table 7. Nonmetallic resources in the study area evaluation of the geothermal potential. The rugged include volcanic cinders at the White Chuck cinder terrain, lack of roads, and remote location would cone and pumice from widespread deposits in the upper hinder possible development of such resources. Chiwawa and Entiat River basins in the Glacier Peak No source beds for oil and gas occur within the Wilderness. A large pumice deposit also occurs just study area, which is almost entirely underlain by south of, but extends into, area 0603ID; there has been igneous and metamorphic rocks and by volcaniclastic minor production from this deposit (see fig. 7; table 7, sediments (Ford and others, in press). Furthermore, no no. 67). No production of pumice can be expected structural traps have been identified in rocks that have from other remote deposits within the study area. not been heated above the breakdown temperature of Nonmetallic commodities occurring adjacent to area hydrocarbons. We consider the study area to have a 06031G consist of subeconomic deposits of marble and low potential for the occurrence of oil and gas placer deposits of garnet. resources. Sand and gravel are abundant, but adequate resources exist outside the study area. Although some REFERENCES CITED talc is produced just northwest of the study area, talc production from the small metaperidotite bodies in the Barton, Paul, 1982, Silver/base metal epithermal central schist belt is not considered practical because deposits, in Erickson, R. L., ed., Characteristics of the sparse distribution and low grade of the of mineral deposit Occurrences: U.S. Geological occurrences. A feldspar deposit is under development Survey Open-File Report 82-795, p. 127-130. near the southern border of the study area; an Beane, R. E., and Titley, S. R., 1981, Porphyry copper evaluation of feldspar potential was not made since no deposits Part II, Hydrothermal alteration and large pegmatitic bodies were found in the igneous or mineralization, in Skinner, B. J., ed., Economic metamorphic terranes. A low potential for Geology, Seventy-fifth anniversary volume: nonmetallic resources is indicated for the study area. Lancaster, Penn., Economic Geology Publishing Co., p. 235-269. Potential for energy resources Beget, J. E., 1982, Recent volcanic activity at Glacier Peak: Science, v. 215, p. 1389-1390. The potential for the occurrence of geothermal Berger, B. R., 1982, The geological attributes of resources must be considered in an area containing a Au-Ag-base metal epithermal deposits, in dormant volcano such as Glacier Peak. Obvious Erickson, R. L., ed., Characteristics of mineral indications of present and recent thermal activity in deposit occurrences: U.S. Geological Survey the wilderness are the three hot springs (fig. 7) and Open-File Report 82-795, p. 119-126. 17th- or 18th-century ash deposits from the Glacier Berger, B. R., and Eimon, P. L, 1983, Comparative Peak volcano (Beget, 1982). No fumarolic activity at models of epithermal silver-gold deposits, in Glacier Peak has been recorded since about 1900. Shanks, W. C., m, ed., Cameron volume on Thermal-spring temperatures are: Kennedy Hot unconventional mineral deposits: American Springs, 35°C (95°F); Sulphur Hot Springs, 37°C Institute of Mining Engineers, p. 191-205. (99°F); and Gamma Hot Springs, 65°C (149°F) (Mariner Bohlke, J. K., 1982, Orogenic (metamorphic-hosted) and others, 1982), Chemical geothermometers gold-quartz veins, in Erickson, R. L. , ed., (Mariner and others, 1982) suggest the following Characteristics of mineral deposit occurrences: aquifer temperatures: Sulphur, 110-117°C U.S. Geological Survey Open-File Report 82-795, (230-243°F); Kennedy, 145-189°C (293-372°F); and p. 70-76. Gamma, 178-216°C (352-421°F). Such temperatures, Boyle, R. W., 1979, The geochemistry of gold and its particularly that of Gamma Hot Springs, suggest a deposits: Canada Geological Survey Bulletin potential for the occurrence of a geothermal resource; 280, 584 p. however, these are indirect estimates, and none of the Brook, C. A., Mariner, R. H., Mabey, D. R., Swanson, springs are associated with siliceous sinter, a general J. R., Guffanti, Marianne, and Muffler, L. J. P., indicator of high subsurface temperature (Mariner and 1979, Hydrothermal convection systems with others, 1982). Gamma Hot Springs has been evaluated reservoir temperatures ^90°C, ir± Muffler, L. J. P., as a small hot-water convection system having ed., Assessment of geothermal resources of the reservoir temperatures greater than 150°C (302°F) United States 1978: U.S. Geological Survey (Brook and others, 1979, p. 56-57). Discharges from at Circular 790, p. 18-85. least six small orifices in and near Gamma Creek, near Brown, A. S., 1976, Morphology and classification, in a small but presently inactive travertine deposit, are Brown, A. 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Washington: U.S. Geological Survey Geologic Durning, W. P., and Davis, J. D., 1978, The root-zone Quadrangle Map GQ-647, scale 1:6Z,500. characteristics of porphyry copper deposits: Chaffee, M. A., 198Za, A generalized empirical model Arizona Geological Society Digest, vol. XI, for porphyry copper deposits geochemical p. 81-89. expression, in Erickson, R. L., ed., Characteristics Engels, J. C., Tabor, R. W., Miller, F. K., and of mineral deposit occurrences: U.S. Geological Obradovich, J. D., 1976, Summary of K-Ar, Rb-Sr, Survey Open-File Report 8Z-795, p. 33-34. U-Pb, Pb, and fission-track ages of rocks from ____198Zb, A geochemical study of the Kalamazoo Washington State prior to 1975 (exclusive of porphyry copper deposit, Final County, Arizona, in Columbia Plateau basalts): U.S. Geological Titley, S. R., ed., Advances in geology of the Survey Miscellaneous Field Studies Map MF-710. porphyry copper deposits Southwestern North Erickson, R. 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L., in press, Preliminary geologic rnap of the collected from the Glacier Peak Wilderness and Glacier Peak Wilderness and adjacent areas, adjacent areas, Washington: U.S. Geological Chelan, Skagit, and Snohomish Counties, Survey Open-File Report 8Z-780, ZZ7 p. Washington: U.S. Geological Survey Miscellaneous Church, S. E., Motooka, J. M., Werschky, R. S., Field Studies Map, scale 1:100,000. Bigelow, R. C., and VanTrump, George, Jr., 1983b, Franklin, J. M., Sangster, D. M., and LyDome Peak Roadless Area, Snohomish County, mine, Abitibi greenstone belt I. Patterns of Washington: U.S. Geological Survey Miscellaneous alteration and metal distribution: Canadian Field Studies Map MF-1380-C, scale 1:50,000. Journal of Earth Science, v. 16, p. 4Z1-439* Colley, Howard, and Greenbaum, David, 1980, The Grant, A. R., 1966, Bedrock geology of the Dome Peak mineral deposits and metallogenesis of the Fiji area, Chelan, Skagit, and Snohomish Counties, Platform: Economic Geology, vol. 75, no. 6, northern Cascades, Washington: Seattle, p. 807-8Z9. University of Washington, Ph.D. thesis, 164 p. Cox, D. P., 198Z, A generalized empirical model for _____1969, Chemical and physical controls for ore porphyry copper deposits, in Erickson, R. L., ed., deposits in the Cascade Range of Washington: Characteristics of mineral deposit occurrences: Washington Division of Mines and GeoloTy Bulletin U.S. Geological Survey Open-File Report 8Z-795, 58, 107 p. p. Z7-3Z. ___198Z, Summary of economic geology data for the Glacier Peak Wilderness, Chelan, Snohnmish, and 31 Skagit Counties, Washington: U.S. Geological Sangster, S. F., 197Z, Pre-Cambrian volcanogenic Survey Open-File Report 8Z-408, 37 p. massive sulfide deposits in Canada A review: Hollister, V. F., 1979, Porphyry copper-type deposits Canada Department of Energy, Mines, and of the Cascade volcanic arc, Washington: Resources Paper 7Z-ZZ, 4Z p. Minerals Science Engineering, v. 11, no. 1, Sherrard, Mark, and Flanigan, V. J., 1983, Bou^uer p. 22-3-5. gravity anomaly map of the Glacier Peak Jackson, E. D., 1968, The chromite deposits of the Wilderness and vicinity, Chelan, Skagit, and Stillwater Complex, Montana, in Ridge, J. D., Snohomish Counties, Washington: U.S. Geological ed., Ore deposits of the United States, Survey Open-File Report 83-595, 6 p. 1933-1967: American Institute of Mining Silberman, M. L., 198Z, Hot-spring type, large tonnage, Engineers, v. 2, p. 1495-1510. low-grade gold deposits, in Erickson, R. L., ed., Kinkel, A. R., Jr., Hall, W. E., and Albers, J. P., 1956, Characteristics of mineral deposit occurrerces: Geology and base-metal deposits of the West U.S. Geological Survey Open-File Report 82-795, Shasta Cu-Zn district, Shasta County, California: p. 131-143. U.S. Geological Survey Professional Paper Z85, Singer, D. A., Page, N. J., Smith, J. G., Blakely, R. J., 156 p. and Johnson, M. G., 1982, Mineral resource Knopf, Adolph, 1929, The mother lode system of assessment of the Medford 1° x 2° quadrar^le, California: U.S. Geological Survey Professional Oregon: U.S. Geological Survey Open-File Report Paper 157, 88 p. 82-1057, 28 p. Lipin, B. R., and Page, N. J., 198Z, Stratiform Spurr, J. E., 1901, The ore deposits of Monte Cristo, chromite, in Erickson, R. L., ed., Characteristics Washington: U.S. Geological Survey Annual of mineral deposit occurrences: U.S. Geological Report 22, pt. 2, p. 777-865. Survey Open-File Report 8Z-795, p. 18-ZO. Stotelmeyer, R. B., Johnson, F. L., McHugh, E. L., Lowell, J. D., and Guilbert, J. M., 1970, Lateral and Federspiel, F. E., Denton, D. K., Jr., and Stebbins, vertical alteration-mineralization zoning in S. 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R., 198Z, The associated explosion breccia, northern Cascade platinum-group chemistry and mineralogy of the Mountains, Washington: Geological Society of UG-2 chromite layer of the Bushveld Complex: America Bulletin, v. 74, p. 1203-1208. Economic Geology, v. 77, p. 1348-1366. Tabor, R. W., and Crowder, D. F., 1969, On batholiths Misch, Peter, 1966, Tectonic evolution of the northern and volcanoes intrusion and eruption of late Cascades of Washington State a west-cordilleran Cenozoic magmas in the Glacier Peak area, nnrth case history: Canadian Institute of Mining and Cascades, Washington: U.S. Geological Survey Metallurgy Special Volume 8, p. 101-148. Professional Paper 604, 67 p. ___1977, Bedrock geology of the north Cascades, in Tabor, R. W., Frizzell, V. A., Jr., Booth, D. B., Brown, E. H., and Ellis, R. C., eds., Geological Whetten, J. T., Waitt, R. B., Jr., and Zartman, excursions in the Pacific Northwest: Geological R. E., 1982, Preliminary geologic map of the Society of America Annual Meeting, Seattle, Skykomish River 1:100,000 quadrargle, 1977, Guidebook, p. 1-62. Washington: U.S. Geological Survey Open-File Moss, C. K., 198Z, Geophysical expressions of porphyry Report 82-747, 31 p. copper deposits, southwest United States, in Tabor, R. W., Frizzell, V. A., Jr., Whetten, J. T., Erickson, R. L., ed., Characteristics of mineral Swanson, D. A., Byerly, G. R., Booth, D. B., deposit occurrences: U.S. Geological Survey Hatherington, M. J., and Waitt, R. B., Jr., 1980, Open-File Report 8Z-795, p. 31-3Z. Preliminary geologic map of the Chelan 1:100>000 Nold, J. L., 1981, The Holden mine, Washington A quadrangle, Washington: U.S. Geological Su-vey metamorphosed volcanogenic deposit [abs.]: Open-File Report 80-841, 46 p. Geological Society of America Abstracts with Titley, S. R., and Beane, R. 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33