U.S. DEPARTMENT OF THE INTERIOR TO ACCOMPANY MAP 1-1867 U.S. GEOLOGICAL SURVEY

GEOLOGIC MAP OF SOUTHEASTERN ALASKA BY George E. Gehrels and Henry C. Berg*

INTRODUCTION age, stratigraphic or intpsive relations, and metamorphic Southeastern Alaska is underlain by Quaternary surficial and structural characteristics of the map units are described deposits and by sedimentary, volcanic, intrusive, and below in the Description of Map Units. The ages of map metamorphic rocks ranging in age from Quaternary to units axe shown on the Correlation of Map Units, and the Proterozoic(?). We have classified these rocks into map general lithic types of the units are listed in the Description units on the basis of their age and lithic type, rather than of Map Units (see map sheet). Table 1 references all their formally recognized names, in an effort to emphasize formally recognized geologic units in southeastern Alaska the regional distribution of lithically similar and generally to our map units and to the geographic regions in which coeval geologic units. The distribution, lithic components, they are found.

Table 1. Formally recognized lithic units, their map symbols, and the geographic regions of southeast Alaska in which they are found. - Formally recognized unit Map symbol Geographic region

Admiralty Island Volcanics Tv Admiralty Island Barlow Cove Formation 'ii Psv Northern Admiralty lsland Bay of Pillars Formation Ss, Sc, scg, sosv Kuiu lsland and nothern Prince or Wales lsland regions Black Cap Limestone Dc Glacier Bay region Bokan Mountain Granite Jgr Southern Prince of Wales Island Bowser Lake Group JMsv Coast Mountains Brothers Volcanics KJV Islands in southern Stephens Passage Burnt lsland Conglomerate Rs Keku Straits area and west of Etolin Island Cannery Formation Ps, MDsv Admiralty and Kupreanof Islands Cedar Cove Formation Ds, Dc, Dcg Eastern Chichagof Island Cenotaph Volcanics Tv West of Glacier Bay Chapin Peak Formation 1v Gravina Island Cornwallis Limestone lc Keku Straits area Coronados Volcanics Dsv Western Prince of Wales Island region Descon Formation sos, sov, sosv, sosvc Prince of Wales lsland region Douglas Island Volcanics KJV, KJsv Juneau area Edgecumbe Volcanics QTv Kruzof Island Freeburn assemblage Ksvm Western Chichagof Island Freshwater Bay Formation Dv Western Chichagof lsland Gambier Bay Formation xosv, xoc Admiralty Island Goon Dip Greenstone lb Western Chichagof lsland Gravina Island Formation KJs, KJV Gravina and Annette lslands Halleck Formation Ps, Pv Keku Straits area Hamilton lsland Limestone Rc Keku Straits area

*?resent addresses: Gehrels: Department of Geosciences University of Arizona Tucson, Arizona 85721 Berg: 115 Malvem Ave. Fullerton, California 92632 Table 1. Formally recognized lithic units, their map symbols, and the geographic regions of southeast Alaska in which they ore found ---Continued.

Formally recognized unit Map symbol Geographic region

Hazelton Group JMsv Coast Mountains Heceta Limestone Sc, scg Prince of Wales lsland region Hood Bay Formation sos Southern Admiralty Island Hound lsland Volcanics Rv Keku Straits area Hyd Formation xsv, x Psv Admiralty lsland Hyd Group lv, Rsv, xc Keku Straits and Annette and Gravina Islands Iyoukeen Formation Mc Eastern Chichagof Island Jualin Diorite Jld Along east shore of Lynn Canal Karheen Formation Ds, Dcg Annette and western Prince of Wales Islands Keku Volcanics R v Keku Straits area Kelp Bay Group Ksvrn Western Chichagof and Baranof Islands Kennel Creek Limestone sc, scg Eastern Chichagof Island Khaz Formation Ksvm Western Chichagof and Baranof Islands Klawak Formation ips Western Prince of Wales Island region Kootznahoo Formation Ts Admiralty, Kuiu, and Zarembo Islands Kuiu Limestone sc, Scg Kuiu and northern Prince of Wales Islands Ladrones Limestone PC Western Prince of Wales Islands region La Perouse gabbro T9b West of Glacier Bay Nehenta Formation + sv Gravina lsland Peratrovich Formation Mc Western Prince of Wales lsland region Pinnacle Peak Phyllite Ksvm Western Chichagof and Baranof Islands Point Augusta Formation Sc, Ss Eastern Chichagof lsland Port Refugio Formation Dv, Dsv Western Prince of Wales Island region Puppets Formation R v Gravina Island Pybus Formation PC Keku Straits area, Admiralty Island, and west of Etolin lsland Pyramid Peak Limestone sc Glacier Bay area Rendu Formation DSsc Glacier Bay area Retreat Group R osv Admiralty Island Saginaw Bay Formation PDsv Keku Straits area Seymour Canal Formation KJs, KJV Etolin-Kupreanof Islands, Admiralty Island, and on mainland near Juneau and Petersburg Shelter Formation KJs, KJsv Southern Lynn Canal Sitka Graywacke Ks Western Chichagof and Baranof lsland Sloko Group Tv Coast Mountains northeast of Juneau St. Joseph lsland Volcanics Dsv Western Prince of Wales Island region Stephens Passage Group KJs, KJV, KJsv Etolin-Kupreanof Islands, Admiralty Island, and on mainland near Juneau and Petersburg Texas Creek Granodiorite Fg Coast Mountains northeast of Ketchikan Tidal Formation Sc, Ss Glacier Bay area Topsy Formation Ts West of Glacier Bay Treadwell Slate KJs Near Juneau Valdez Group Ks, Kv, Ksv, West of Glacier Bay Wadleigh Limestone Dc Western Prince of Wales Island region Wales Group pOmsv, pOmc Southern Prince of Wales Island region Waterfall Greenstone Kvm Western Chichagof Island Whitestripe Marble Rc Western Chichagof Island Willoughby Limestone Sc Glacier Bay area Yakataga Formation QTs West of Glacier Bay The rocks of southeastern Alaska have been classified according to the probable age of formation of the into four principle categories: (1) stratified rocks; (2) melange, rather than the depositional age of the undivided stratified and (or) metamorphosed and (or) constituent strata, and to the principle lithic type of the deformed rocks; (3) highly metamorphosed and (or) strata. The nature and age of the melange and of the deformed rocks; and (4) intrusive rocks. The categories of rocks in each unit are discussed in the Description of units are defined as follows: Map Units. For example, unit Ksvm consists of Units of the stratified rocks category consist of sedimentay and volcanic rocks (and their deformed sedimentary and (or) volcanic rocks, and in some areas and metamorphosed equivalents) that belong to a their regionally metamorphosed and (or) deformed melange that formed during Cretaceous time. equivalents, that generally conform to the Law of The belt of regionally disrupted rocks has some Superposition (North American Commission on characteristics of a melange, but the stratigraphic and Stratigraphic Nomenclature, 1983). Strata that belong to a (or) structural relations between various lithic particular unit in this category are generally similar in lithic components of the belt are uncertain. Map units in this type, stratigraphic position, and age of deposition and are, belt are classified according to the main lithic type and unless otherwise noted, interpreted to be generally the probable age of deposition of the constituent correlative. Such strata generally constitute formations, strata. The nature and age of the belt and of the rocks lithic components of formations or groups, or unnamed in each unit are described in the Description of Map geologic units of formation rank. An example of a unit 03f Units. For example, unit KDsd consists of clastic this type is Sc, which includes Silurian carbonate rocks that sedimentay rocks of Cretaceous through Devonian (I) constitute the predominant rock type in the Heceta, age that belong to a belt of strongly disrupted and Kuiu, Willoughby, and Pyramid Peak Limestones, anci at deformed rocks. least part of the Kennel Creek Limestone, (2) are a (2) Metamorphic units, which comprise rocks in which subordinate component in units composed predominantly primary stratigraphic relations were obliterated during regional metamorphism. Metamorphic units are of Silurian clastic strata (Bay of Pillars, Point Augusta, and Tidal Formations), and (3) belong to unnamed geologic classified according to the probable lithic type and units of formation rank. depositional age of protoliths and are denoted by a Units of the undivided stratified and (or) lower case "m" preceding the lithic term in the unit metamorphosed and (or) deformed rocks category symbol. Their metamorphic rock types and the nature comprise stratified rocks and (or) their metamorphosed and age of metamorphism are discussed in the and (or) deformed equivalents that were not assigned to Description of Map Units. For example, unit pTrnsv other categories of units because (1) their degree of consists of metasedimentaw and metavolcanic rocks deformation and (or) metamorphism are poorly known, (2) (generally schist and gneiss) derived from pre-Tertiary sedimentary and volcanic rocks. they are found in geologic units that grade from relatively Units of the intrusive rocks category consist of intrusive intact stratigraphic sequences to metamorphic or structural rocks that are classified into map units according to their units, or (3) they are known or interpreted to include two age of emplacement (following the Decade of North or more geologic units of formation rank that are not American Geology Geologic Time Scale (Palmer, 1983)), generally coeval. Most units of this category probably and to their predominant rock types (following the consist of, or were derived from, several stratified units of International Union of Geological Sciences classification formation rank. These units are classified according to the scheme (Streckheisen, 1976)). probable minimum and maximum depositional age and Areas in which intrusive rocks contain a significant the main lithic type of their constituent strata. An example component of country rock are shown by a stipple pattern of this type of map unit is XOsv, which consists of poorly on the geologic map. These types of mixed rocks are known sedimentary and volcanic rocks of probable Triassic referred to as migmatites in some of the references cited to Ordovician age that are stratified in some areas and are below. Where country rock predominates over intrusive regionally metamorphosed and deformed in others. rock, the map unit corresponds to the country rock and the Units of the highly metamorphosed and (or) deformed stipple pattern indicates that a significant propottion of the rocks category comprise rocks that were regionally area is underlain by younger intrusive rock. For example, metamorphosed and (or) deformed to a degree that their Triassic to Ordovician sedimentary and volcanic rocks primay stratigraphic relations are not preserved (that is, (XOsv) on Admiralty Island are patterned where they the rocks do not conform to the Law of Superposition) contain a significant proportion of younger intrusive rock. (North American Commission on Stratigraphic Where younger intrusive rock predominates, the rocks are Nomenclature, 1983). We assigned such rocks of assigned to an intrusive unit and the stipple pattern southeastern Alaska to two types of units: indicates that a significant proportion of the area is (1) Structural units, which consist of rocks that are underlain by older country rock. Intrusive unit TKg, for deformed or disrupted to a degree that their primary example, is patterned where Paleocene and Cretaceous stratigraphic relations are no longer preserved, Such granodiorite bodies contain abundant unmapped inclusions units in southeastern Alaska constitute a melange or pendants of pre-Tertiary metasedimentay and (denoted by a lower case "mu at the end of the unit metavoicanic rocks elsewhere assigned to unit pTmsv. symbol) and a belt of regionally disrupted rocks Some stippled intrusive rocks contain unmapped inclusions (denoted by a lower-case "d" at the end of the unit of country rock and are also intruded by younger igneous symbol). Map units in the melange are classified rocks. ACKNOWLEDGMENTS and Ford, 1985); and andesitic to rhyolitic We thank George Plafker, Travis Hudson, Earl Redman, tuff and breccia (Sloko Group) of Eocene E.C. Robertson, Chris Dodds, and J.B. Saleeby for age northeast of Juneau (Brew and Ford, allowing us to use their unpublished data, and George 1985; Souther, 1971). Volcanic rocks Plafker and R.L. Elliott for helpful comments on the map northwest of Cross Sound are interbedded and text. with clastic strata belonging to the Topsy Formation (unit Ts) (Brew and others, DESCRIPTION OF MAP UNITS 1978), and the Admiralty lsland Volcanics contain clastic strata that may be in part [See footnotes in Correlation of Map Units for restrictions correlative with the Kootznahoo Formation on age designations] (unit Ts) (Lathram and others, 1965) Ts Sedimentary rocks (TertiarybNonmarine SURFlClAL DEPOSITS sandstone, shale, and conglomerate 0s Surficial sedimentary deposits (Quaternary)- (Kootznahoo Formation) in the Zarembo- Unnamed lacustrine, fluvial, colluvial, glacial, Kuiu lslands region (Brew and others, 1984) beach, and marine deposits that are found in and on Admiralty lsland (Lathram and many areas of southeastern Alaska others, 1965), and marine calcareous sandstone and siltstone (Topsy Formation) of STRATIFIED ROCKS Miocene age northwest of Cross Sound [May include metamorphosed and (or) deformed rocks] (Brew and others, 1978; Marincovich, 1979). Age of the Kootznahoo Formation is QTv Volcanic rocks (Quaternary and Tertiary)-- reported to be Eocene and Paleocene in the Edgecumbe Volcanics (basalt, andesite, and Zarembo-Kuiu lslands region and Miocene to dacite) on Kruzof lsland (Loney and others, Eocene on Admiralty Island (Brew and 1975) and unnamed basaltic to rhyolitic others, 1984) rocks on islands west of Prince of Wales Tsv Sedimentary and volcanic rocks, undivided lsland (Eberlein and others, 1983), on (TertiarybUnnamed carbonaceous shale, Revillagigedo Island and mainland to east sandstone, and conglomerate of probable (Berg and others, 1978, 1988), near Paleogene age and subordinate Oligocene Alaska-British Columbia border east of volcanic rocks near Haines (George Plafker, Wrangell Island (Elliott and Koch, 1981), written commun., 1984; E.C. Robertson, and on Zarembo, Kuiu, and Kupreanof written commun., 1984; Campbell and Islands (Brew and others, 1984). Rocks of Dodds, 1983) Holocene age were recognized east of Ks Sedimentary rocks (Cretaceouswandstone Wrangell lsland (Elliott and others, 1981) and mudstone turbidites and subordinate and on Kruzof lsland (Loney and others, conglomerate (Sitka Graywacke) on 1975), and basaltic rocks of Holocene and Baranof, Chichagof, Kruzof, and Yakobi (or) Pleistocene age are found on southern lslands (Loney and others, 1975; Johnson Kupreanof lsland (Brew and others, 1984, and Karl, 1985; Decker, 1980) and 1985) and perhaps at other localities, Most regionally metamorphosed carbonaceous volcanic rocks in this unit on Zarembo, siltstone, volcanogenic graywacke, mud- Kupreanof, and Kuiu lslands are probably stone, and minor conglomerate (Valdez correlative with rocks in the Tertiary volcanic Group) north of Cross Sound (Brew and rocks unit (Tv) others, 1978; George Plafker, written QTs Sedimentary rocks (Quaterna y and comrnun., 1984). Strata are interpreted to be TertiarybPleistocene to Miocene marine deep-water marine trench, slope-basin, and mudstone, siltstone, sandstone, and fan deposits. The Sitka Graywacke is conglomerate (Yakataga Formation) moderately deformed and disrupted, northwest of Cross Sound (Plafker and regionally metamorphosed as high as Addicott, 1976; George Plafker, written greenschist facies in some areas, and commun., 1984) thermally upgraded to hornblende-hornfels Tv Volcanic rocks (TertiarybOligocene and Eocene facies locally (Decker and others, 1979; basalt and andesite (Admiralty lsland Johnson and Karl, 1985). Common rock Volcanics) on Admiralty lsland (Lathram and types in metamorphosed regions south of others, 1965); unnamed Oligocene basaltic Cross Sound include metagraywacke and rocks on islands in Icy Strait (Hudson and argillite. Rocks north of Cross Sound are others, 1982); basaltic rocks (Cenotaph regionally metamorphosed from Volcanics) of Miocene and Oligocene age subgreenschist facies to as high as along coast northwest of Cross Sound (Brew amphibolite facies, producing graywacke and others, 1978); unnamed Pliocene(?) and semischist, phyllite, slate, and layered schist, Miocene(?) andesite in Glacier Bay (Brew semischist, and gneiss (Brew and others, 1978). These metasedimentary rocks are (unit Ts) of Miocene to Paleocene age correlated with strata in the Valdez Group to (Buddington and Chapin, 1929). Fossils northwest by lithic similarity (Brew and range in age from Cenomanian or Albian to Morrell, 1979) and by stratigraphic continuity Late and possibly Middle Jurassic (Berg and (Plafker and Campbell, 1979; Campbell and others, 1972; Brew and others, 1984). Unit Dodds, 1983). Early Cretaceous fossils were consists of (1)the Gravina lsland Formation found in the Sitka Graywacke on Kruzof and unnamed strata on Gravina lsland (Berg lsland (Reed and Coats, 1941); minimum and others, 1978, 1988); (2) unnamed age of these strata is constrained by Eocene strata on Annette Island, Revillagigedo granodiorite (Tgd) on Baranof lsland (Loney Island, southern Etolin Island, and adjacent and others, 1975). The Sitka Graywacke and parts of mainland (Berg and others, 1978, rocks north of Cross Sound are considered 1988; Eberlein and others, 1983); (3) the to be Cretaceous in age on the basis of these Seymour Canal Formation (part of the constraints and correlation with lithically Stephens Passage Group) and its similar rocks in the Yakutat Group and metamorphic equivalents near Etolin and Valdez Group (Plafker and others, 1977; Kupreanof Islands and adjacent areas of Brew and Morrell, 1979) mainland (Buddington and Chapin, 1929; Kv Volcanic rocks (Cretaceous)--Basalt and Brew and others, 1984): (4) an unnamed basaltic tuff north of Cross Sound that are unit of sandstone and mudstone in Keku deformed and regionally metamorphosed as Strait (Muffler, 1967); (5) the Seymour high as amphibolite facies (Brew and others, Canal Formation on Admiralty lsland 1978; George Plafker, written commun., (Lathram and others, 1965), northern 1984). Common rock types include schist, Kupreanof lsland (Brew and others, 1984), gneiss, and amphibolite (Brew and others, and perhaps near Cape Fanshaw (Muffler, 1978). Correlation with volcanic rocks in 1967; Buddington and Chapin, 1929); (6) Valdez Group to northwest indicates a the now-abandoned Symonds Formation Cretaceous age (Plafker and Campbell, (strata reassigned to the Seymour Canal 1979; Brew and Morrell, 1979) Formation) and the Shelter Formation on Ksv Sedimentary and volcanic rocks, undivided islands in southern Lynn Canal (Barker, (Cretaceous)-Interbedded sedimentary and 1957; Brew and Ford, 1985); (7) the volcanic rocks, and their metamorphosed Treadwell Slate and unnamed strata near equivalents, that are cotrelative and Juneau (Ford and Brew, 1973, 1977; Brew continuous with Cretaceous sedimentary (KS) and Ford, 1985); (8) part of the now- and volcanic (Kv) rocks. Found north of abandoned Berners Formation (strata Cross Sound (Brew and others, 1978; Brew reassigned, in part, to the Seymour Canal and Morrell, 1979; Plafker and Campbell, Formation) northwest of Juneau (Knopf, 1979), Age constraints, lithic types, 1911, 1912; Martin, 1926; Buddington and metamorphic characteristics, and regional Chapin, 1929; Redman, 1984a; Brew and correlations are similar to those described Ford, 1985); and (9) argillite, siltstone, and above for Cretaceous sedimentary (Ks) and sandstone of probable Cretaceous and volcanic (Kv) rocks. Jurassic age south of Haines (George KJs Sedimentary rocks (Cretaceous and Plafker, written commun., 1984) Jurassic)--Marine graywacke and KJsv Volcanic rocks (Cretaceous and Jurassic& mudstone, subordinate conglomerate and Andesitic to basaltic flows, flow breccia, andesitic to basaltic volcanic rocks, minor agglomerate, and tuff (generally containing limestone, and regionally metamorphosed conspicuous clinopyroxene phenocysts), and deformed equivalents of these strata. subordinate graywacke and mudstone, and Metamorphic grade generally increases from regionally metamorphosed and deformed subgreenschist facies or nonmetamorphosed equivalents of these strata. Greenschist-facies on southwest to greenschist and in some metamorphism in some areas yielded areas amphibolite facies to northeast. Rock common rock types of greenstone and types in higher grade parts of unit are greenschist. Age constrained by primarily phyllite, schist, and gneiss. Strata intertonguing stratigraphic relations with are queried on geologic map where Cretaceous and Jurassic sedimentay rocks metamorphism and deformation, or lack of (KJs). Geologic and geochemical stratigraphic information, make correlation considerations suggest that some volcanic with sedimentay rocks of known Cretaceous rocks in this unit are genetically related to and Jurassic age uncertain. Regional Early Cretaceous ultramafic bodies (unit metamorphism and deformation occurred Kurn) (Irvine, 1973, 1974) and possibly to after Early Cretaceous time and prior to Early Cretaceous and (or) Jurassic diorite deposition of the Kootznahoo Formation (KJd) and gabbro (KJgb) (Berg and others, 1978, 1988). Unit consists of (1) volcanic and basalt (Chapin Peak Formation; part of rocks (Gravina lsland Formation) on Gravina the Hyd Group) on Gravina Island (Berg, lsland (Berg and others, 1978, 1988); (2) 1982; Berg and others, 1978, 1988; unnamed rocks on Annette and Gehrels and others, 1986, 1987); and (3) Revillagigedo lslands and adjacent areas of rhyolite and subordinate basalt (Keku mainland (Berg and others, 1978, 1988; Volcanics) and basalt and andesite (Hound Eberlein and others, 1983); (3) unnamed Island Volcanics; part of the Hyd Group) in rocks in the Etolin-Kupreanof lslands region Keku Strait (Muffler, 1967; Brew and others, and adjacent areas of mainland (Brew and 1984) others, 1984; Buddington and Chapin, 'k sv Sedimentary and volcanic rocks, undivided 1929); (4) the Douglas Island Volcanics and (Triassic)-Black shale, shaly limestone, the Brothers Volcanics (part of Stephens siltstone, sandstone, conglomerate, and Passage Group) on and near Admiralty limestone; felsic, intermediate, and mafic Island (Lathram and others, 1965) and in flows; and minor black chert. Rocks vay the Juneau area (Ford and Brew, 1973, from relatively unmetamorphosed to as high 1977; Brew and Ford, 1985); and (5)part of as greenschist facies. Common rock types in the now-abandoned Berners Formation higher grade areas include phyllite, slate, (strata reassigned, in part, to the Douglas semischist, marble, greenschist, and Island Volcanics) northwest of Juneau greenstone. Unit consists of (1) the Nehenta (Knopf, 1912; Martin, 1926; Brew and Ford, Formation and other strata (parts of the Hyd 1985) Group) on Annette and Gravina lslands KJsv Sedimentary and volcanic rocks, undivided (Berg and others, 1978, 1988; Gehrels (Cretaceous and Jurassic&Moderately and others, 1987); (2) unnamed strata in the deformed and metamorphosed graywacke, belt of disrupted rocks (units KDsd and mudstone, sandstone, and andesitic to KDvd) on Kupreanof and Zarembo Islands basaltic rocks. Strata belong to the Shelter (Brew, 1982; Brew and others, 1984; Berg Formation in southern Lynn Canal (Barker, and Gybeck, 1980; McClelland and 1957) and are undifferentiated correlatives of Gehrels, 1987); and (3)the part of the Hyd the Treadwell Slate (unit KJs), the Seymour Formation (Hyd Group of Muffler, 1967, in Canal Formation (unit KJs), and the Douglas Keku Islet area) on Admiralty Island that was Island Volcanics (unit KJV) near Juneau reliably separated from the Cannery (Ford and Brew, 1973, 1977; Brew and Formation (unit Ps) (Lathram and others, Ford, 1985) 1965) Sedimentary rocks (TriassictUpper Triassic "kc Carbonate rocks (TriassictMassive to thick- conglomerate, limestone, and calcareous bedded limestone and minor dolomite in siltstone and sandstone (Burnt Island most areas, but in Keku Strait unit includes Conglomerate) west of Etolin Island (Karl, thin-bedded, dark-gray limestone, and on 1984) and on northwestern Kupreanof Chichagof Island unit consists of massive Island (Muffler, 1967); unnamed silty white to gray marble (Whitestripe Marble). limestone of Late Triassic age on small Diagnostic fossils from limestone and islands between Etolin lsland and northern dolomite are Late Triassic in age. Marble on Prince of Wales lsland (Brew and others, Chichagof lsland is assigned a Triassic(?)age 1984); and unnamed conglomerate and by Loney and others (1975), but is sedimentary breccia of probable Late Triassic interpreted by Plafker and others (1976) and age on east-central Prince of Wales lsland Jones and others (1977) to be Late Triassic (Buddington and Chapin, 1929; Eberlein by correlation with the Chitistone Limestone and others, 1983; Gehrels and others, 1987) in the Wrangell Mountains of southern 'A v Volcanic rocks (rhyolitic to basaltic) Alaska. Plafker and others (1976) and Jones (Triassic)-Basaltic pillow flows, pillow and others (1977) also suggest that the breccia, and breccia; rhyolitic tuff with Whitestripe Marble is not correlative with calcareous interbeds, flow breccia, and other carbonate rocks included in this unit. banded ash-flow tuff; and subordinate Unit consists of (1) limestone and marble andesitic breccia and aquagene tuff. Rocks in (parts of the Hyd Group) on Annette and most areas are moderately recrystallized and Gravina lslands (Berg and others, 1978, deformed. Fossils from interbedded rocks or 1988; Berg, 1982; Gehrels and others, from conformable adjacent strata indicate 1987); (2) the Cornwallis Limestone and deposition during Norian and Carnian time. Hamilton lsland Limestone (parts of the Hyd Unit consists of (1)rhyolite (part of the Hyd Group) on northern Kuiu and Kupreanof Group) on Annette Island (Berg, 1982; lslands (Muffler, 1967; Brew and others, Gehrels and others, 1987); (2) rhyolite 1984); and (3) the Whitestripe Marble on (Puppets Formation; part of the Hyd Group) Chichagof Island (Loney and others, 1975; Johnson and Karl, 1985) of Permian(?) age on mainland east of 7ib Basaltic rocks (Triassic&Basaltic flows and Admiralty Island (Brew and Gybeck, 1984); flow breccia (Goon Dip Greenstone) on (2) medium-bedded dolomite, limestone, Chichagof and Yakobi Islands that were and subordinate gray chert beds and nodules deposited, at least in part, in subaerial (Pybus Formation) on northern Kuiu and environments (Loney and others, 1975; Kupreanof Islands (Lower Permian) (Muffler, Johnson and Karl, 1985) and unnamed 1967; Brew and others, 1984), Admiralty basalt near Haines (Plafker and Hudson, Island (Permian) (Lathram and others, 1980; Redman and others, 1984; E.C. 1965), and a small island between northern Robertson, written commun., 1984; Davis Prince of Wales and Etolin Island (Lower and Plalker, 1985). The Goon Dip Permian) (Brew and others, 1984); and (3) Greenstone is assigned a Triassic(?) age by unnamed fossiliferous gray limestone, cherty Loney and others (1975), but Plafker and limestone, and limestone conglomerate oi others (1976) and Jones and others (1977) Permian age northeast of Glacier Bay (Brew suggest that the Goon Dip Greenstone is and others, 1978) and along west shore of probably correlative with the Upper and (or) Lynn Canal (Lathram and others, 1959; Middle Triassic Nikolai Greenstone in the Brew and Ford, 1985). Marble on Wrangell Mountains of southern Alaska. Revillagigedo Island and on mainland east of Basalt near Haines yields Carnian fossils and Admiralty Island may not be correlative with is also interpreted by Davis and Plafker Permian carbonate rocks elsewhere in map (1985) to be correlative with the Nikolai area (Silberling and others, 1982) Greenstone IPS Sedimentary rocks (PennsylvaniantMiddle Rsc Clastic sedimentary and carbonate rocks, and Lower Pennsylvanian sandstone and undivided (TriassickUnnamed, moderately siltstone containing minor limestone and deformed and metamorphosed graphitic chert-pebble conglomerate (Klawak limestone and slate of late Ladinian Formation). Unit found on west-central (latest Middle Triassic) age on Revillagigedo Prince of Wales Island (Eberlein and others, lsland (Silberling and others, 1982). On the 1983) basis of regional stratigraphic relations and PC Carbonate rocks (Pennsylvanian)--Massive slightly older age, Silberling and others limestone and minor dolomite containing (1982) and Berg and others (1972) suggest light-gray chert nodules (Ladrones that these strata are not correlative with Limestone) on west-central Prince of Wales strata assigned to other Triassic units lsland (Eberlein and others, 1983) and (unitsffs, ffc, and Rsv) unnamed, medium-bedded to massive Ps Sedimentary rocks (PermiantBlack argillite, crinoidal limestone on northern Kuiu Island graywacke, calcareous siltstone, chert, and (Brew and others, 1984). Fossils indic'ite minor basaltic rocks, limestone, and deposition during Middle and Early conglomerate. Unit consists of (1)part of the Pennsylvanian time Halleck Formation of Early Permian age near Mc Carbonate rocks (Mississippian)-Thin- to Keku Strait (Muffler,1967; Brew and others, thick-bedded, dark-gray limestone, 1984; Jones and others, 1981); (2) the subordinate beds and nodules of light-gray Canney Formation on southern Admiralty chert, and minor shale and gypsum. Unit Island (reported to be Early Permian in age, consists of the Peratrovich Formation on Lathram and others, 1965); and (3) western Prince of Wales Island (Eberlein and unnamed Permian strata northeast of Glacier others, 1983) and the lyoukeen Formation Bay (Brew and others, 1978). Strata locally on Chichagof Island (Loney and others, metamorphosed to slate and phyllite 1975). Strata deposited during Late and Pv Volcanic rocks (PermianbLower Permian Early Mississippian time basalt (part of the Halleck Formation) on MDsv Sedimentary and volcanic rocks, undivided northern Kuiu lsland (Muffler, 1967) and (Mississippian and DevoniantTuffaceous unnamed Permian basaltic(?) rocks northeast argillite and graywacke and subordinate of Glacier Bay (Brew and others, 1978). Age chert, limestone. and andesitic volcanic rocks constrained by interbedded Lower Permian (Canney Formation) on northern Kupreanof clastic strata (unit Ps) on Kuiu Island and lsland (Muffler, 1967; Brew and others, interbedded Permian carbonate rocks (PC)in 1984). Fossils are Late Devonian and Early Glacier Bay area and Late Mississippian in age (Jones and PC Carbonate rocks (Permian)-Consists of (1) others, 1981) greenschist-facies, massive to thin-bedded DS Sedimentary rocks (Devonian)-Siltstone, marble of Early Permian age on shale, sandstone, graywacke, and Revillagigedo Island (Silberling and others, subordinate limestone breccia, arkose, 1982; Berg and others, 1978, 1988) and conglomerate-, and volcanic rocks. Unit consists of (1)the Lower Devonian Karheen part of the Cedar Cove Formation (Upper Formation in the Annette-Gravina Islands and Middle Devonian) on Chichagof lsland area (Gehrels and others, 1987) and on (Loney and others, 1975); (5)the Black Cap southern Prince of Wales lsland (Herreid and Limestone (Middle Devonian) in Glacier Bay others, 1978; Gehrels and Saleeby, 1986, (Rossman, 1963; Brew and others, 1978); 1987a; Savage and Gehrels, 1984); (2) and (6) strata correlative with the Black Cap unnamed Lower Devonian strata on west- Limestone in Chilkat Range and along west central Prince of Wales Island and on smaller shore of Lynn Canal (Lathram and others, islands to west (Eberlein and others, 1983); 1959; Loney and others, 1975; Brew and (3) unnamed Devonian(?) graywacke, Ford, 1985) argillite, and arkose on northern Kuiu lsland DC~ Conglomeratic rocks (DevoniankCon- (Brew and others, 1984); and (4) undivided glomerate and sedimentary breccia part of the Devonian Cedar Cove Formation interbedded with sandstone, siltstone, shale, on northeastern Chichagof lsland (Loney and minor graywacke, limestone, and and others, 1975) volcanic rocks. Sedimentary structures and Volcanic rocks (DevoniantBasaltic and presence of red beds and thick sections of subordinate andesitic pillow flows, breccia, coarse conglomerate suggest that strata in aquagene tuff, and minor sedimentary Prince of Wales Island region were deposited interbeds, Unit consists of (1) unnamed in subaerial to shallow-water marine basaltic-andesitic pillow flows and breccia environments (Ovenshine, 1975; Gehrels (Lower Devonian) on small islands south of and Saleeby, 1987a). Strata on Chichagof Annette lsland (Gehrels and others, 1987) Island were probably also deposited in a and on southern Prince of Wales lsland shallow-water marine environment (Loney (Herreid and others, 1978; Gehrels and and others, 1975). Unit consists of the Saleeby, 1986, 1987a); (2) basaltic rocks in Lower Devonian Karheen Formation on the Port Refugio Formation (Upper southern Prince of Wales lsland (Gehrels and Devonian) on west-central Prince of Wales Saleeby, 1986, 1987a) and on central Prince Island (Eberlein and others, 1983); (3) of Wales Island (Eberlein and others, 1983), Lower Devonian rhyolite in Kasaan Bay on and conglomeratic rocks in the Cedar Cove east-central Prince of Wales lsland (Eberlein Formation on Chichagof Island (Loney and and others, 1983; Savage, 1981); and (4) others, 1975) that we interpret to be Upper Devonian andesite, basalt, and minor generally correlative with the Lower rhyolite (Freshwater Bay Formation) on Devonian Karheen Formation Chichagof Island (Loney and others, 1975) Sc Carbonate rocks (SiluriantMassive, thin- to Dsv Sedimentary and volcanic rocks, undivided thick-bedded, locally reefoidal, light-gray (Devonian)-Siltstone, shale, volcanogenic limestone and subordinate shale and graywacke, conglomerate, and minor polymictic conglomerate. Unit consists of (1) limestone that are interbedded with basaltic unnamed Silurian limestone and marble on pillow flows, breccia, and aquagene tuff. Unit Dall and Long Islands (Eberlein and others, consists of the Coronados Volcanics 1983; Gehrels and Saleeby, 1987b; G.E. (Devonian), the Devonian(?) St. Joseph Gehrels, unpub. data, 1984); (2) part of the Island Volcanics, and part of the Upper Upper and Lower Silurian Heceta Limestone Devonian Port Refugio Formation, all of on Prince of Wales Island (Eberlein and which are found on western Prince of Wales others, 1983; Brew and others, 1984); (3) Island and adjacent islands (Eberlein and the Upper Silurian Kuiu Limestone and others, 1983) limestone layers in the Upper and Lower Carbonate rocks (Devonian)-Thin-bedded to Silurian Bay of Pillars Formation on Kuiu massive, gray limestone and minor shale Island (Muffler, 1967; Brew and others, interbeds. Unit consists of (1)the Upper and 1984); (4) the Kennel Creek Limestone Middle (and probably upper Lower) (Devonian and (or) Silurian; the Silurian age Devonian Wadleigh Limestone in west- is favored by Loney and others, 1975) and central Prince of Wales lsland region limestone layers in the Upper(?) Silurian (Eberlein and others, 1983; Savage and Point Augusta Formation on Chichagof Gehrels, 1984); (2) unnamed Lower Island (Loney and others, 1975); (5) the Devonian limestone on east-central Prince of Willoughby Limestone, Pyramid Peak Wales lsland (Eberlein and others, 1983); (3) Limestone, and limestone layers in the Tidal unnamed Middle and Lower Devonian Formation (all considered to be Silurian by limestone and marble in belt of disrupted Rossman, 1963) in the Glacier Bay area rocks (units KDsd and ~Dvd)on Kupreanof (Rossman, 1963; Brew and others, 1978); Island (Brew, 1982; Brew and others, 1984; and (6) unnamed Devonian and Silurian(?) McClelland and Gehrels, 1987); (4) upper limestone in Chilkat Range (Lathram and others, 1959; Brew and Ford, 1985). Loney volcanic breccia, agglomerate, and flows and and others (1975) report that limestone in greenschist and greenstone derived from the Chilkat Range is lithically similar to the these rocks. Found with Silurian sedimentay Kennel Creek Limestone and contains (Ss) and carbonate rocks (Sc) belonging to similar fossils. On the basis of these the Bay of Pillars Formation on southern obsetvatiorls and apparent similarity in Kuiu lsland (Brew and others, 1984) stratigraphic position, we interpret limestone SOs Sedimentary rocks (Silurian and Ordoviciant in "limestone and marble" and "siliceous Mudstone and graywacke turbidites, argillite and volcanic" units of Lathram and subordinate conglomerate, sandstone, and others (1959) to be correlative with the shale, and minor limestone, chert, and basalt Kennel Creek Limestone and limestone flows and breccia. Unit consists of (1) layers in the Point Augusta Formation on unnamed strata of probable Early Silurian to Chichagof Island. Although stratigraphic Middle Ordovician age on Sukkwan and Dall relations and fossils indicate that most strata Islands (Eberlein and others, 1983; Gehrels in unit are Silurian in age, deposition of and Saleeby, 1987b; G.E. Gehrels, unpub. strata in some areas possibly continued into data, 1984); (2) unnamed strata of Silurian Early Devonian time and (or) Ordovician age on Forrester lsland Scg Conglomeratic rocks (SiluriantPolymictic (Clark and others, 1971); (3) Lower Silurian pebble and cobble conglomerate and to Lower Ordovician strata belonging to the subordinate sedimentay breccia, Descon Formation and unnamed units on olistostromal deposits, sandstone, graywacke, southern Prince of Wales Island (Eberlein mudstone, and limestone. Clasts consist of and others, 1983; Gehrels and Saleeby, porphyritic andesite, limestone, graywacke, 1987a, b; Herreid and others, 1978); (4) mudstone, granitic to gabbroic intrusive part of the Lower Silurian to Lower rocks, chert, and other rocks derived from Ordovician Descon Formation on central and various pre-Devonian units. Unit consists of northern Prince of Wales lsland (Eberlein layers and lenses of polymictic conglomerate and others, 1983; Brew and others, 1984); in (1) unnamed units on northern Prince of and (5) thin-bedded black argillite, black Wales lsland (Brew and others, 1984); (2) chert, and black impure limestone of the Heceta Limestone (unit Sc) and the Bay Ordovician age (Hood Bay Formation) on of Pillars Formation (unit Ss) on central and southern Admiralty lsland (Lathram and northern Prince of Wales lsland (Eberlein others, 1965; Carter, 1977) and others, 1983; Brew and others, 1984); SOv Volcanic rocks (Silurian and Ordovician)-- (3) the Kuiu Limestone (unit Sc) and the Basaltic pillow flows, pillow breccia, and Bay of Pillars Formation on Kuiu lsland aquagene tuff; massive andesitic pyroclastic (Brew and others, 1984); and (4) the Kennel breccia; felsic breccia and tuff; subordinate Creek Limestone (unit Sc) on Chichagof interbeds of mudstone and graywacke lsland (Loney and others, 1975) turbidites; and metamorphic equivalents of Ss Sedimentary rocks (SiluriantGraywacke and these strata. Unit consists of (1) mafic to mudstone turbidites and subordinate felsic rocks (part of the Descon Formation) olistostromal deposits, layers and lenses of an southern Prince of Wales Island (Gehrels limestone, and conglomerate. Unit consists and Saleeby, 1986, 1987a); (2) unnamed of (1) most of the Bay of Pillars Formation basalt and rnetabasalt on Long and southern (Upper and Lower Silurian) on northern Dall Islands (Gehrels and Saleeby, 1987b; Prince of Wales lsland and Kuiu Island G.E. Gehrels, unpub. data, 1984); and (3) (Brew and others, 1984); (2) the Upper(?) basaltic rocks (part of the Descon Formation) Silurian Point Augusta Formation on and unnamed andesitic breccia on central Chichagof lsland (Loney and others, 1975); Prince of Wales lsland (Eberlein and others, (3) the Upper Silurian Tidal Formation in 1983). Age constrained by stratigraphic Glacier Bay (Rossman, 1963; Brew and relations with Lower Silurian to Lower others, 1978); and (4) clastic sedimentary Ordovician sedimentary rocks (unit SOs), rocks belonging to the Devonian and intrusive relations with plutons of Early Silurian(?) units of Lathram and others Silurian and Late Ordovician age (unit SOq), (1959) in the Chilkat Range (interpreted to and Early Silurian and Late Ordovician be Upper Silurian by Loney and others, potassium-argon apparent ages of volcanic 1975, and Brew and Ford, 1985). Although rocks (Eberlein and others, 1983; Gehrels stratigraphic relations and fossils indicate that and Saleeby, 1987a) most strata in unit are Silurian in age, SOsv Sedimentary and volcanic rocks, undivided deposition of strata in some areas possibly (Silurian and OrdoviciantMudstone and continued into Early Devonian time graywacke turbidites, basaltic and andesitic Sv Volcanic rocks (Silurian)--Mafic to intermediate volcanic rocks, and metamorphic equivalents of these strata. Unit consists of (1)part of the recovered from carbonaceous slate and Descon Formation on Prince of wales Island limestone assigned to this map unit near (Eberlein and others, 1983); (2) Juneau (Ford and Brew, 1977; H.C. Berg, metasedimentary and metavolcanic rocks on unpub. data, 1981), and similar strata southeastern Prince of Wales Island that are (locally mapped as Triassic clastic assigned to the Descon Formation (Eberlein sedimentary and carbonate rocks (Xsc)) on and others, 1983) but may be part of the Revillagigedo Island yielded latest Middle Wales Group (called the Wales metamorphic Triassic fauna (Silberling and others, 1982). suite by Gehrels and Saleeby, 1987a) (units On Revillagigedo Island, phyllite and pOrnsv and p0mc) (Redman, 1981); (3) metagraywacke are locally in depositional moderately deformed and metamorphosed contact with crinoidal marble of known andesitic to dacitic volcanic rocks and Permian age (unit PC) and are interbedded subordinate clastic strata (part of the Descon with crinoidal marble of probable Permian Formation) on Annette and Duke Islands age (Berg and others, 1978, 1988; H.C. (Gehrels and others, 1987); (4) unnamed Berg, unpub. data, 1975). Some strata metasedimentay and rnetavolcanic rocks included in this unit are interpreted to be near Cape Fox (Berg and others, 1978, Cretaceous or Jurassic in age on the basis of 1988; G.E. Gehrels and J.B. Saleeby, the following observations: (1) Berg unpub. data, 1983); and (5) conglomerate, and others (1978, 1988) report that agglomerate, and volcanic breccia (part of metasedimentay rocks in this unit on the Bay of Pillars Formation) of probable Revillagigedo Island are locally identical in Early Silurian age on northern Prince of protolith to Cretaceous and Jurassic strata Wales Island (Brew and others, 1984) (unit KJs) on Annette and Gravina Islands; SOsvc Clastic sedimentary, volcanic, and carbonate (2) Brew and others (1984) suggest that rocks, undivided (Silurian and some rocks in this unit on mainland east of Ordovician)-Interbedded graywacke, Kupreanof Island may have Cretaceous or mudstone, mafic to felsic volcanic rocks, and Jurassic protolith ages; and (3) Buddington limestone that have been regionally and Chapin (1929, p. 74) report that metamorphosed as high as greenschiit facie; conglomerate and phyllite in this unit on (Gehrels and Saleeby, 1987b; G.E. Gehrels, mainland east of Adrniraltv Island are unpub. data, 1984). Found along west coast lithically similar to conglomerate and slate of of Dall lsland and on Long Island and Cretaceous and Jurassic age (unit KJs) on interpreted to be coeval with nearby Lower eastern Admiralty Island. Contact between Silurian to Lower Ordovician rocks of the rocks of Cretaceous and Jurassic age (units Descon Formation (units SOv, SOs, and KJs, KJV, and KJsv) and Cretaceous to SOsv) on the basis of similarities in Permian rocks in this and associated map stratigraphic position and lithic type (Gehrels units (units KPv and KPsv) is located along and Saleeby, 1987b; G.E. Gehrels, unpub. northeast margin of relatively homogeneous data, 1984) metagraywacke and phyllite. Intrusive bodies of Late Cretaceous age UNDIVIDED STRATIFIED AND (OR) (unit Kgt) place a younger limit on METAMORPHOSED AND (OR) depositional age of these strata. Age of DEFORMED ROCKS metamorphism and deformation has KPs Sedimentary rocks (Cretaceous to Permian& traditionally been interpreted to be Late Carbonaceous shale, mudstone, and Cretaceous and (or) early Tertiay graywacke; subordinate limestone, chert, (Buddington and Chapin, 1929). However, conglomerate, and mafic volcanic rocks; recognition of (1) an unconforrnity minor felsic volcanic rocks; and the separating metasedimenta y and metamorphosed and deformed equivalents metavolcanic rocks of probable Triassic or of these rocks. Regional metamorphic grade Permian age (unit KPsv) from less in these strata and in associated Cretaceous metamorphosed Cretaceous and Jurassic to Permian volcanic and sedimentary rocks strata (unit KJs) northwest of Juneau (units KPv and KPsv) generally increases (Redman, 1984a); and (2) a greater degree from subgreenschist or greenschist facies on of metamorphism and deformation in this southwest to amphibolite facies toward unit than in strata of probable Cretaceous northeast. There are also significant changes and Jurassic age on Revillagigedo Island in metamorphic grade along northwest trend (G.E. Gehrels, unpub. data, 1984) suggest of these map units. Common rock types in that some rocks in this unit may have been higher grade strata include phyllite, schist, metamorphosed and deformed prior to and gneiss. Late Triassic fossils were deposition of Cretaceous and Jurassic strata. Consists of unnamed rocks on Revillagigedo J.B. Saleeby, unpub. data, 1984). The Work Island (Berg and others, 1978. 1988) and Channel amphibolite to southeast in British on mainland east of Kupreanof Island (Brew Columbia (Hutchison, 1982) and some and others, 1984), east of Admiralty lsland amphibolite in Cretaceous to Permian map (Brew and Grybeck, 1984; Buddington and units to northwest may consist in part of Chapin, 1929), and east of Juneau (Ford correlative metagabbro. Unit found on (1) and Brew, 1973, 1977; Brew and Ford, Revillagigedo Island and adjacent areas of 1977, 1985) mainland to southeast (Berg and others, KPv Volcanic rocks (Cretaceous to Permiant 1978, 1988) and northwest (Elliott and Andesitic or basaltic flows and locally Koch, 1981); (2) mainland east of Admiralty fragmental rocks, subordinate clastic strata Island (Buddington and Chapin, 1929; Brew and carbonate, and the metamorphosed and and Grybeck, 1984; Brew and Ford 1977, deformed equivalents of these rocks. 1985; Ford and Brew, 1973, 1977); and (3) Regional metamorphism of these strata is east side of Lynn Canal (Buddington and similar to that described above for Chapin, 1929; Redman, 1984a) Cretaceous to Permian sedimentay rocks KPsvc Clastic sedimentary, volcanic, and carbonate (KPs). Common rock types in higher grade rocks (Cretaceous to Permiantunnamed regions include schist, gneiss, and fossiliferous argillite of Cretaceous age; amphibolite, although some of this variably metamorphosed chert, tuffaceous amphibolite may be metagabbro (see sandstone, felsic tuff, argillite, and light-gray, sedimentary and volcanic rock unit KPsv thin-bedded limestone of Mesozoic or described below). Graphitic slate assigned to Paleozoic age; highly sheared meta- unit contains Late Triassic fossils near sedimentay, metavolcanic, and granodioritic Juneau (Brew and Grybeck, 1984, p. 31), rocks of Mesozoic and Paleozoic(?) age; and and marble intercalated with metavolcanic amphibolite, gneiss, schist, and marble of rocks contains Permian and Permian(?) Mesozoic or Paleozoic age (Johnson and fossils near Juneau, along coast southeast of Karl, 1985; Loney and others, 1975). We Juneau, and in Endicott Arm (Buddington assign a maximum age of Permian on the and Chapin, 1929, p. 73, 119; Ford and basis of our interpretation that the oldest Brew, 1973; Brew and Gybeck, 1984, p. rocks in this unit are found beneath nearby 3031). Minimum depositional age Triassic basaltic rocks (Rb) and may be constrained by interbedded Cretaceous to equivalent to Permian strata that underlie Permian sedimentary rocks (KPs) and by correlative Triassic basaltic rocks in Wrangell crosscuttins- Late Cretaceous intrusive bodies Mountains of southern Alaska (Plafker and (unit Kgt). Consists of unnamed rocks on others, 1976; Jones and others, 1977). Revillagigedo Island (Berg and others, 1978, Found on Chichagof, Baranof, and Yakobi 1988) and on mainland east of Kupreanof Islands. Strata in this unit are probably not Island (Brew and others, 1984), east of correlative with rocks belonging to other Admiralty Island (Brew and Grybeck, 1984; Cretaceous to Permian units (units KPs, KPv, Buddington and Chapin, 19291, and east of and KPsv). Areas that may be underlain by Juneau (Ford and Brew, 1973, 1977; Brew a significant proportion of intrusive rock are and Ford, 1977, 1985) shown with a stipple pattern KPsv Sedimentary and volcanic rocks, undivided JMsv Sedimentary and volcanic rocks, undivided (Cretaceous to Permian)-Shale, mud- (Jurassic to Mississippiant-Diverse stone, graywacke, andesitic or basaltic rocks, assemblage of sedimentary and volcanic subordinate chert and carbonate rocks, and rocks and their metamorphic equivalents. the regionally metamorphosed equivalents of Found near British Columbia-Alaska border these strata. Nature and age of northeast of Revillagigedo lsland (Berg and metamorphism is similar to that described others, 1978, 1988; Elliott and Koch, above for Cretaceous to Permian 1981) and east of Juneau (Souther and sedimentay rocks (KPs). Protolith age others, 1979; Souther, 1971). Unit consists indicated by stratigraphic relations with of (1)unnamed Middle Jurassic rhyolite and sedimentary and volcanic rocks of andesite; (2) Lower Jurassic andesite, basalt, Cretaceous to Permian age (units KPs and conglomerate, and sandstone of the KPv). Stippled area in unit southeast of Hazelton Group; (3)Upper Triassic andesite Revillagigedo Island represents and clastic sedimentay rocks; (4) Permian metasedimentay and metavolcanic rocks limestone; and (5) Carboniferous intruded by deformed and metamorphosed greenstone, limestone, and clastic gabbro (recrystallized to amphibolite) that is sedimentary rocks (Hutchison and others, apparently related to foliated Paleocene and 1979; Berg and others, 1978, 1988; Cretaceous tonalite (TKt) (G.E. Gehrels and Souther and others, 1979; Souther, 1971). Rocks locally metamorphosed to semischist, the Ordovician Hood Bay Formation (unit phyllite, and schist. Nearby rnetasedimentay SOs), and various strata elsewhere assigned and metavolcanic rocks of pre-Tertiary age to Devonian, Silurian, or Ordovician units. (p~rnsv)probably consist in large part of Rocks in part of unit may also belong to belt higher grade equivalents of these strata of regionally disrupted rocks (units KDS~and *PC Carbonate rocks (Triassic and (or) Permian)- KDvd). Areas on Admiralty Island that may Unfossiliferous marble on mainland be underlain by a significant proportion of northwest of Revillagigedo Island (H.C. younger intrusive rock are shown with a Berg, unpub. data, 1975) and on and stipple pattern. northeast of Etolin Island (Brew and others, In the Chilkat Range west of Haines unit 1984). Age inferred from similarity with consists of unnamed metasedimentary and Triassic and Permian marble layers included metavolcanic rocks (MacKevett and others, in units of Cretaceous to Permian 1974; E.C. Robertson, written comrnun., sedimentary rocks (KPs) and of Permian 1984; Redman, 1984b) that are of known carbonate rocks (PC) Mississippian age (Redman and others, Si Psv Sedimentary and volcanic rocks, undivided 1985) and probable Triassic to middle (Triassic and Permian)--Andesitic to Paleozoic age (MacKevett and others, 1974; basaltic pillow flows, breccia, and tuff; felsic Berg and Gybeck, 1980; Redman, 1984b). tuff; graywacke, mudstone, shale, chert, These rocks are herein interpreted to be conglomerate, and carbonate; and the predominantly correlative with sedimentary metamorphic equivalents of these strata. Unit and volcanic rocks of Permian, Devonian, consists of the Barlow Cove Formation and Silurian age in Glacier Bay (Brew and (Barker, 1957) and strata belonging to the others, 1978) and in the Chilkat Range Hyd Formation (Upper Triassic) and the (Lathram and others, 1959; Brew and Ford, Cannery Formation (Lower Permian) 1985) and of Triassic to Ordovician age (Lathram and others, 1965). Phyllite, along British Columbia-Alaska border north greenstone, greenschist, and marble are of Glacier Bay (Campbell and Dodds, 1983) common rock types in this unit, but nature EOc Carbonate rocks (Triassic to Ordoviciant and age of metamorphism are poorly known Carbonate rocks regionally metamorphosed XOsv Sedimentary and volcanic rocks, undivided to gray marble (MacKevett and others, 1974; (Triassic to Ordovician~lastic sedi- Lathram and others, 1959; Brew and Ford, mentary rocks, subordinate mafic to felsic 1985; Redman and others, 1985). Fossils of volcanic rocks, thin- to thick-bedded gray Pennsylvanian(?) or Permian(?), carbonate, chert, and minor ultramafic rocks Paleozoic(?), and Devonian(?) or Silurian(?) that have been regionally metamorphosed to age were recovered from unit west of Haines slate, phyllite, greenschist, schist, gneiss, and (MacKevett and others, 1974) and fossils of marble in many areas. Age and grades of probable Mississippian age were recovered metamorphism have not been reliably from marble in associated Triassic to determined. Rocks assigned to unit on Ordovician strata (unit ROsv) (Redman and Admiralty Island belong to the Garnbier Bay others, 1985). Adjacent units in British Formation, the Retreat Group, and the Columbia consist of carbonate rocks of "undifferentiated metamorphic rocks" and Triassic, Devonian, Silurian, and Ordovician the "migmatite, gneiss, and feldspathic age (Campbell and Dodds, 1983). Age of schist" units of Lathram and others (1965). strata in unit on Admiralty Island (referred to Devonian fossils were recovered from marble as part of Gambier Bay Formation) is in the Gambier Bay Formation; the Retreat constrained by stratigraphic relations with Group is inferred to be Devonian in age on Triassic to Ordovician clastic strata (unit the basis of correlation with the Gambier ~Osv).Regional map patterns suggest that Bay Formation; and the undivided most carbonate rocks in this map unit are metamorphic rocks are undated (Lathram probably of Silurian age and correlative with and others, 1965). The Triassic to the Kennel Creek, Pyramid Peak, and Ordovician age assignment on Admiralty Willoughby Limestones (unit Sc) Island reflects our interpretation that this map PDsv Sedimentary and volcanic rocks, undivided unit consists primarily of regionally (Pennsylvanian to Devonianwaginaw metamorphosed and deformed strata Bay Formation on Kuiu Island. From correlative with the Upper Triassic Hyd youngest to oldest, unit consists of silty Formation (unit Xsv), the Permian Pybus limestone, calcareous chert and limestone, Formation (unit Pc) and Cannery Formation black chert, and massive aquagene tuff and (unit Ps on Admiralty Island), the pillow breccia (Muffler, 1967). Silty Mississippian and Devonian Cannery limestone and calcareous chert and Formation (unit MDsv on Kupreanof Island), limestone are known to be Middle and Lower Pennsylvanian; age of black chert is to thin- to thick-bedded, dark-gray to white not known directly; and volcanic rocks marble. Consists of unnamed rocks on yielded earliest Late to latest Early Devonian northeastern Chichagof Island and in Glacier conodonts (Dutro and others, 1981; Brew Bay area. Loney and others (1975) suggest and others, 1984) that marble on Chichagof lsland was derived DSV Volcanic rocks (Devonian and Siluriant primarily from limestone in the Point Unnamed Devonian or Silurian andesitic(?) Augusta Formation (unit Sc). Marble in volcanic rocks found in a fault slice on Glacier Bay area was derived in large part northern Kuiu lsland (Muffler, 1967; Brew from limestone of Devonian (unit Dc), and others, 1984); unnamed Devonian and Silurian (unit Sc), or Devonian and Silurian Silurian basaltic and (or) andesitic rocks in (DSC)age (Brew and others, 1978). Some Glacier Bay (Brew and others, 1978); and marble in unit may be correlative with unnamed Devonian(?) and Devonian to Ordovician limestone in map units along Silurian(?) basalt and andesite in the Chilkat Alaska-British Columbia border northwest of Range and along west shore of Lynn Canal Glacier Bay (Campbell and Dodds, 1983). (Lathram and others, 1959; Loney and Metamorphic relations are the same as for others, 1975; Brew and Ford, 1985), Devonian to Ordovician sedimentay and Volcanic rocks in Glacier Bay and in Chilkat volcanic rocks (DOsv) Range may be in part or entirely correlative DSC Carbonate rocks (Devonian and Silurian)-- with the Upper Devonian Freshwater Bay Thin, discontinuous, unfossiliferous limestone Formation (unit Dv) or volcanic rocks of layers associated with Devonian and Silurian Silurian age (units Sv or SOv), or, as volcanic rocks (DSv) in the Chilkat Range suggested by Brew and Ford (19851, they (Lathram and others, 1959; Brew and Ford, may range in age from Middle Devonian 1985) through Late Silurian DSsc Sedimentary rocks (Devonian and Siluriant DOsv Sedimentary and volcanic rocks, undivided On north-central Prince of Wales lsland unit (Devonian to Ordovician)-Graywacke, consists of unnamed limestone, sandstone, mudstone, shale, limestone, and subordinate calcareous mudstone, and polymictic mafic to intermediate volcanic rocks that conglomerate interpreted to be facies have been metamorphosed in most areas to equivalents of the Silurian Heceta Limestone hornfels, slate, phyllite, schist, amphibolite, (unit Sc), associated Silurian clastic strata marble, gneiss, and granofels. Unit consists (units Ss and Scg), and the Lower Devonian of unnamed rocks on northeastern Karheen Formation (unit Dcg) (Eberlein and Chichagof Island, in Glacier Bay area, and in others, 1983). In Glacier Bay, unit consists of the Chilkat Range. Loney and others (1975) unnamed clastic sedimentay and minor suggest that metamorphic rocks on carbonate and volcanic rocks and of Chichagof lsland were derived mainly from Devonian and (or) Silurian argillite and the Point Augusta Formation (unit Ss) and limestone (Rendu Formation) (Rossrnan, from Devonian volcanic rocks of the 1963; Brew and others, 1978; Brew and Freshwater Bay Formation (unit Dv). In Ford, 1985). Strata in Glacier Bay may be Glacier Bay area and the Chilkat Range lateral equivalents of the Tidal Formation rocks are probably the metamorphic (Upper Silurian) (units Ss and Sc), the Point equivalents of Devonian and Silurian strata Augusta Formation (Upper? Silurian) (unit found nearby (units Ds, Ov, Dcg, Ss, Sc, Ss and Sc) and lower part of the Devonian DSSC, DSc, and DSV) (Lathram and others, Cedar Cove Formation (units Dcg and Ds) 1959; Brew and others, 1978; Brew and Ford, 1985). We suggest that this unit also HIGHLY METAMORPHOSED AND (OR) includes rocks of Ordovician age because DEFORMED ROCKS Ordovician strata are found in contiguous Melange map units northwest of Glacier Bay in British Columbia (Campbell and Dodds, 1983). On Melange (CretaceoustMelange of regionally northeastern Chichagof Island, strata were disrupted, deformed, and metamorphosed metamomhosed to hornblende-homfels marine sedimentay and volcanic rocks. facies during emplacement of adjacent Divided into: Cretaceous intrusive rocks (Loney and Ksvm Sedimentary and volcanic rocks, others, 1975). Metamorphism in Glacier Bay undivided-Consists of (1) blocks as much area is also interpreted to have occurred as several kilometers in length of marine during Cretaceous time (Brew and others, sedimentay and volcanic rocks, and their 1978) metamorphic equivalents, that are bounded DOC Carbonate rocks (Devonian to Ordovician)- by faults or shear zones; and (2) blocks as Carbonate rocks that were metamorphosed much as several tens of meters in length of marine sedimentay and volcanic rocks, and gray quartzite, and graywacke semischist. their metamorphic equivalents, enclosed in a Age of formation of this melange unit is matrix of moderately metamorphosed and constrained by stratigraphic and structural penetratively sheared graywacke, argillite, similarities with rocks in associated tuff, and pillow breccia. Common lithic types Cretaceous melange units (units Ksvm and in blocks include tuffaceous argillite, tuff, Kvm). Fossils were not recovered from rocks greenstone, graywacke, chert, limestone, in this unit, Consists of unnamed rocks marble, phyllite, schist, and minor granitic mapped by Loney and others (1975) as rocks. Fossils from blocks are Early "phyllite" and "graywacke semischist" units Cretaceous, Late Jurassic, and Jurassic(?) or on Baranof Island Triassic(?) in age (Loney and others, 1975; Kvm Volcanic rocksIncludes mafic volcanic and Johnson and Karl, 1985). Minimum age of metavolcanic rocks that resemble rocks in unit is constrained by (1) mid-Cretaceous the Cretaceous sedimentary and volcanic potassium-argon apparent ages on rocks melange unit (Ksvm) in structural and metamorphic minerals in the melange on metamomhic characteristics. Common lithic Chichagof Island (Decker and others, 1980); types include greenstone, greenschist, and (2) Early Cretaceous fossils in sedimentay minor phyllite, graywacke semischist, marble, matrix material near Sitka on Baranof Island and rnetachert. Age of formation of this (Plafker and others, 1976); and (3) Early melange unit is constrained by stratigraphic Cretaceous fossils in matrix material near the and structural similarities with rocks in coast northwest of Cross Sound (Plafker and associated Cretaceous melange units (units others, 1977; George Plafker, written Ksvm and Ksm). Consists of the Waterfall commun., 1984). Cretaceous age assigned Greenstone on western Chichagof Island, to unit refers to time during which melange which yielded radiolaria of Early Cretaceous is interpreted to have formed. Metamorphic age (Johnson and Karl, 1985), and grade is primarily subgreenschist, unnamed metavolcanic rocks on Baranof greenschist, and, south of Cross Sound, Island that are referred to as "greenschist glaucophane-schist facies (Decker and and greenstone" unit by Loney and others others, 1980). On Chichagof Island, unit (1975) consists of the Khaz Formation, which is a melange of blocks enclosed in a sedimentary Disrupted rocks and volcanic matrix. and the Freeburn Disrupted rocks (Cretaceous to Devonian )- assemblage, which consists of fault-bounded Belt of regionally disrupted rocks that have blocks of sedimentay and volcanic rocks some characteristics of a melange, but (Decker, 1980; Karl and others, 1982; relations between blocks and matrix are Johnson and Karl. 1985). The Freeburn uncertain. Divided into: assemblage comprises rocks described by KDsd Sedimentary rocks-Deformed, disrupted, Loney and others (1975) as the Pinnacle and metamorphosed graywacke, siltstone, Peak Phyllite and an unnamed schist unit in mudstone, and subordinate chert, limestone, the Kelp Bay Group. On Baranof Island, unit and volcanic and intrusive rocks that belong consists of rocks described by Loney and to a belt of regionally disrupted rocks in the others (1975) as the Khaz Formation, part of Kupreanof-Etolin Islands area. Common the undivided Kelp Bay Group, and an metamorphic rock types include sub- unnamed "schist, gneiss, amphibolite, and greenschist- to greenschist-facies graywacke greenschist" unit (Karl and others, 1982). semischist, phyllite, argillite, slate, and Northwest of Cross Sound, unit consists of subordinate greenstone, greenschist, and melange between Brady Glacier and Border marble. Unit consists of blocks as much as Ranges faults (Tarr Inlet suture zone) that is several kilometers in length of Triassic continuous and probably correlative with sedimentay and volcanic rocks (isv), part of melange on Chichagof and Baranof Permian carbonate rocks (PC), and Devonian Islands (Decker and Plafker, 1982) and part carbonate rocks (Dc) enclosed in a matrix of of melange facies of the Yakutat Group west strata belonging to the Stephens Passage of the Fairweather fault (Plafker and others, Group (Lower Cretaceous and Jurassic, unit 1977; George Plafker, written commun., KJs) and perhaps the Canney Formation 1984) (Mississippian and Upper Devonian, unit Ksm Sedimentary rocks-Includes sedimentary MDsv) or other Mesozoic or Paleozoic units and metasedimentarv rocks that are similar (Brew, 1982; Brew and others, 1984; H.C. in structural and metamorphic characteristics Berg, unpub. data, 1978; McClelland and to rocks in the Cretaceous sedimentay and Gehrels, 1987) volcanic melange unit (Ksvm). Common KDvd Volcanic rocks-Deformed, disrupted, and lithic types include dark-gray phyllite, light- metamorphosed mafic to intermediate and minor felsic volcanic rocks that belong to a adjacent to, and perhaps overlie, high-grade belt of regionally disrupted rocks in the metamorphic rocks (Brew and others, 1985); Kupreanof-Zarembo Islands area. Rocks (4) relations southeast of map area in generally metamorphosed to greenschist and Portland Canal-Terrace area which suggest greenstone. Presence of relict pyroxene that similar metamorphic rocks were derived phenocysts suggests that some metavolcanic from Cretaceous and Jurassic strata rocks were probably derived from (Douglas, 1986), the Jurassic Bowser Lake Cretaceous and Jurassic volcanic rocks Group (Woodsworth and others, 1983, p. (KJV), although metavolcanic rocks of 13; Hill, 1985a), and strata of probable Triassic (unit lv) and Mississippian and Late Permian (Hill, 1985b) and pre-Permian age Devonian (unit MDsv) age may also be (Hutchison, 1982); and (5) map patterns included (Brew and others, 1984; suggesting that rocks in unit were derived in McClelland and Gehrels, 1987) part from nearby Jurassic to Mississippian sedimentay and volcanic rocks (JMsv). Metamorphic rocks Regional metamorphism apparently occurred Metamorphic rocks (pre-Tertiary and pre- (1) during early Tertiary to Late Cretaceous Ordovician)--Units in which primary time (Forbes and Engels, 1970; Smith and stratigraphic relations were obliterated during Diggles, 1981; Gehrels and others, 1984); regional metamorphism. Divided into: (2) after deposition of sedimentay and pTmsv Metasedimentary and metavolcanic rocks volcanic rocks of probable Triassic or (pre-TertiaybMetasedimentay and meta- Permian age (belonging to map unit KPsv) volcanic rocks derived from pre-Tertiary and prior to deposition of Cretaceous and sedimentay and volcanic rocks during Jurassic strata (unit KJs) (see discussion of regional amphibolite- and local granulite- Cretaceous to Permian sedimentary rocks, facies metamorphism. Common rock types KPs); (3) in part prior to Late Triassic time include pelitic, semipelitic, and quartzo- (Souther, 1971; Brew and others, 1985); feldspathic schist and gneiss, and and (4) perhaps during mid-Paleozoic to subordinate amphibolite, quartzite, marble, Proterozoic or other time. Unit consists of and calc-silicate. Protoliths are interpreted to unnamed rocks in Coast Mountains east of be argillaceous marine strata, limestone, Ketchikan (Berg and others, 1978, 1988; chert. subordinate mafic to felsic volcanic Elliott and Koch, 1981), east of Petersburg rocks, and minor intrusive rocks. Areas in (Brew and others, 1984; Souther and others, which there may be a significant proportion 1979), near Tracy Arm (Brew and Grybeck, of unmapped Tertiay or Cretaceous 1984), near Juneau (Ford and Brew, 1973; intrusive rocks are shown with a stipple Brew and Ford, 1977, 1985; Souther and pattern. Such areas comprise migmatite map others, 1979), southeast of Haines (Souther units in some reports cited in this study (for and others, 1979; Werner, 1978), and near example, Brew and Gybeck, 1984; Brew Skagway (Redman and others, 1984) and others. 1984; Brew and Ford, 1985). pTmc Metacarbonate rocks (pre-Tertiaryt Minimum age of rocks in unit is Metacarbonate rocks derived from pre- constrained by crosscutting tonalitic bodies of Tertiarv carbonate rocks and carbonate-rich Paleocene and Late Cretaceous age (unit clastic strata during regional amphibolite-and TKt) in the Coast Mountains (Gehrels and local granulite-facies metamorphism. Found others, 1984), Protolith ages of as discontinuous marble lenses. as thick Cretaceous(?), Jurassic(?), Triassic, Per- continuous marble layers, and as calc-silicate mian(?), Carboniferous(?), and gneiss. Age constrained by intercalation with Proterozoic(?) are indicated by (I) relations pre-Tertiary metasedimentay and meta- along Alaska-British Columbia border east of volcanic rocks (pTmsv) described above. Juneau which suggest that rocks in this unit Found in Coast Mountains northeast of grade into strata of Triassic and older age Petersburg (Brew and others, 1984) and and that these Triassic rocks locally contain southeast of Juneau (Brew and Grybeck, clasts of older metamorphic rocks (Souther, 1984) 1971); (2) a preliminary rubidium-strontium pOmsv Metasedimentary and rnetavolcanic rocks isochron of Proterozoic apparent age (R.L. (pre-OrdovicianbMetasedimentay and Armstrong, oral commun., 1984) determined metavolcanic rocks derived from pre- on high-grade metamorphic rocks along Ordovician basaltic to andesitic pillow flows, Alaska-British Columbia border north of pillow breccia, and tuff breccia, volcaniclastic Juneau (Souther and others, 1979; Werner, graywacke and mudstone, and minor 1978); (3) occurrence of Triassic strata near limestone and felsic volcanic breccia and tuff Alaska-British Columbia border north of during regional greenschist- and local Juneau (not shown on map) which are amphibolite-facies metamorphism. Common rock types include greenschist, greenstone, Yimmelberg, 1983) quartz-white mica schist, and marble. Tgr Granite (Miocene and OligoceoetBiotite + Radiometric age constraints suggest that hornblende 4 pyroxene granite, alkali metamorphism occurred during Early granite, quartz monzonite, and subordinate Ordovician to Middle Cambrian time (Turner syenite, granodiorite, and diorite. Unit and others, 1977; Gehrels and Saleeby, consists of (1)stocks on mainland southeast 1987a. b; M.A. Lanphere, oral commun., of Revillagigedo Island that yield potassium- 1984). Pre-Ordovician protolith ages are argon apparent ages of early Miocene and indicated by intrusive relations with Oligocene (Berg and others, 1978; 1988); Cambrian diorite and granodiorite (Cdg) on (2) large plutons of Miocene %nd (or) eastern Prince of Wales Island and on Oligocene age on Etolin, Zarembo, southernmost Gravina Island (Gehrels and Kupreanof, and Kuiu Islands (Brew and others, 1987). Unit consists of part of the others, 1984); and (3)part of the Oligocene Wales Group (called the Wales metamorphic Tkope River intrusions along Alaska-British suite by Gehrels and Saleeby, 1987a) on (1) Columbia border north of Glacier Bay south-central Prince of Wales Island (MacKevett and others, 1974; Campbell and (Eberlein and others, 1983; Gehrels and Dodds, 1983) Saleeby, 1987a); (2) small islands south of TQ~ Granodiorite (Oligocene and EocenekBiotite Gravina Island (Gehrels and others, 1987); k hornblende + muscovite 2 garnet and (3) Dall Island (Gehrels and Saleeby, granodiorite, granite, quartz monzonite, 1987b; G.E.Gehrels, unpub. data, 1984) tonalite, and quartz diorite. Unit consists of pOmc Metacarbonate rocks (pre-Ordovician)- muscovite- and locally garnet-bearing Metacarbonate rocks derived from pre- granodiorite, granite, and tonalite on Baranof Ordovician carbonate rocks during regional and Chichagof Islands and in Glacier Bay. greenschist- and local amphibolite-facies Where dated, these intrusive bodies yield metamorphism. Found as thin to thick Eocene potassium-argon apparent ages marble layers and lenses intercalated with (Loney and others, 1975; Decker and pre-Ordovician metasedimentay and Plafker, 1982; Johnson and Karl, 1985; metavolcanic rocks (pOmsv). Pre-Ordovician Brew and others, 1978). In the Chilkat protolith age and Early Ordovician to Middle Range and on southeastern Baranof Island, Cambrian metamorphic age are indicated by intrusive bodies consist of biotite- and intercalation with the pre-Ordovician hornblende-bearing quartz diorite and metasedimentay and metavolcanic rocks granodiorite that yield Oligocene potassium- (pOmsv). Unit consists of part of the Wales argon apparent ages (Loney and others, Group (called the Wales metamorphic suite 1975; MacKevett and others, 1974; Brew by Gehrel~and Saleeby, 1987a) on southern and Ford, 1985) Prince of Wales Island (Eberlein and others, Tg Granodiorite (Eocene)-Biotite-dominant, hom- 1983) blende- and sphene-bearing granodiorite and subordinate quark monzonite, quartz INTRUSIVE ROCKS diorite, and leucogranite found in Coast [May include metamorphosed and (or) Mountains (Berg and others, 1978, 1988; deformed rocks] Elliott and Koch, 1981; Brew and others, Tgb Gabbro (Miocene and OligocenetLayered 1984; Webster, 1984; Brew and Gybeck, and locally zoned bodies of two-pyroxene + 1984; Brew and Ford, 1977, 1985; Souther olivine biotite + hornblende + quartz and others, 1979; Redman and others, gabbro and subordinate troctolite, peridotite, 1984; Barker and others, 1986). Concordant leucogabbro, diorite, and tonalite. Unit potassium-argon apparent ages on consists of stocks on Revillagigedo Island and hornblende and biotite (Forbes and Engels, adjacent mainland (Berg and others, 1978, 1970; Smith and others, 1979) and 1988; Koch and Elliott, 1984), northern uranium-lead (zircon) apparent ages Kupreanof and Kuiu Islands (Brew and (Gehrels and others, 1984) indicate others, 19841, Chichagof Island (Johnson emplacement during Eocene time and Karl, 1985; Loney and others, 1975), Tgt Granodiorite and tonalite (Paleocene)-Biotite- and north of Cross Sound (Brew and others, dominant, hornblende-bearing granodiorite 1978). Stocks on Revilagigedo Island and and tonalite containing local foliation and adjacent areas of mainland yield potassium- layering, Uraninum-lead (zircon) data argon apparent ages of early Miocene and indicate emplacement during Paleocene time late Oligocene (Smith and Diggles, 1981), (Gehrels and others, 1984). Found in Coast and large body (La Perouse gabbro) Mountains east of Petersburg (Brew and northwest of Cross Sound yields a *ArIsAr others, 1984), east of Juneau (Brew and apparent age of Oligocene (Loney and Ford, 1977, 1985; Gehrels and others, 1984), and near Skagway (Barker and 1983; Zen and Hammarstrom, 1984a,b), in others, 1986) Etolin-Kupreanof Islands area (Brew and TKt Tonalite (Paleocene and Cretaceous)- others, 1984; Burrell, 1984; Buddington and Hornblende-dominant, biotite-bearing ton- Chapin, 1929), on mainland east of alite and subordinate quartz diorite found as Admiralty Island (Buddington and Chapin, steeply dipping, foliated, and locally lineated 1929; Brew and Gybeck, 1984; Souther sills in Coast Mountains (Brew and Ford, and others, 1979; Brew and Ford, 1985), 1981). Found near Ketchikan (Berg and and in the Haines region (MacKevett and others, 1978, 1988; Elliott and Koch, others, 1974; Redman and others, 1984; 1981), near Petersburg (Brew and others, Earl Redman, written commun., 1985). 1984), near Juneau (Brew and Grybeck, Plutons that are mineralogically or 1984; Brew and Ford, 1977, 1985), and compositionally different from main suite of north of Haines (MacKevett and others, intrusive bodies are queried on geologic map 1974; Redman and others, 1984; E.C. ~db Diorite and gabbro (Cretaceous~Hornblende Robertson, written commun., 1984; Barker diorite and gabbro that grades laterally into and others, 1986). Field and uranium-lead granodiorite and quartz diorite (unit Kgt). (zircon) data indicate emplacement in Potassium-argon ages are Late cretaceous Paleocene and Late Cretaceous time, during (Redman and others, 1984). Found in the waning stages of deformation and Haines area metamorphism in Coast Mountains (Gehrels Kum Ultramafic rocks (Cretaceous)--Ultramafic and others, 1984; Brew and Ford, 1981) intrusive bodies of magnetite-bearing TK~ Granodiorite (Paleocene and Cretaceous& hornblende clinopyroxenite and subordinate Diverse assemblage of generally foliated and dunite, peridotite, and hornblendite (Taylor, layered granodiorite, quartz monzonite, 1967). Several complexes are concentrically tonalite, and their metamorphic equivalents. zoned from a core of dunite to rocks May include a significant component of pre- containing progressively less olivine and Tertiary metasedimentary and metavolcanic more hornblende and magnetite. Zoned rocks (pTmsv) in some areas. Where bodies commonly intrude a two-pyroxene recognized, such areas are indicated by a gabbro known to be of Late Triassic age on stipple pattern. Constraints on age provided Duke Island (Gehrels and others, 1987). by crosscutting Eocene granodiorite plutons Geologic and geochemical considerations (Tg) and the interpretation that some rocks suggest that rocks in these bodies may be in this unit have experienced regional early genetically related to some Cretaceous and Tertiay to Late Cretaceous metamorphism Jurassic volcanic rocks (KJV) (Berg and (Forbes and Engels, 1970; Smith and others, 1972; Irvine, 1973). Potassium-argon Diggles, 1981). We suspect, however, that apparent ages of the ultramafic rocks indicate most rocks in this unit are correlative with emplacement during Early Cretaceous time rocks in the Paleocene granodiorite and (Lanphere and Eberlein, 1966). Rocks tonalite unit (unit Tgt). Found in Coast belonging to this suite are found on (1)Duke Mountains east and north of Ketchikan (Berg Island (Irvine, 1967, 1974); (2) Annette and and others, 1978, 1988; Elliott and Koch, Revillagigedo Islands (Berg and others, 1981), east of Petersburg (Brew and others, 1978, 1988); (3) small islands west of 1984), east of Admiralty Island (Brew and Etolin Island (Himmelberg and others, 1986) Gybeck, 1984), and in Skagway area and Kupreanof Island (Brew and others, (Barker and others, 1986) 1984); and (4) on mainland near Myers Kgt Granodiorite and Tonalite (Cretaceous~mall Chuck (Ruckmick and Noble, 1959), Tracy plutons to batholiths of granodiorite, tonalite, Arm (Brew and Gybeck, 1984), and and subordinate qua& monzonite to quartz Klukwan (MacKevett and others, 1974). diorite and diorite. Most bodies contain Undated ultramafic rocks provisionally biotite and hornblende, many have assigned to unit on the basis of similar lithic magmatic epidote and garnet and are type are queried on geologic map and plagioclase porphyritic, and some contain consist of (1) homblendite and hornblende pyroxene and (or) muscovite. Potassium- pyroxenite on Revillagigedo Island (Berg and argon and 40Ar/3YAr,and uranium-lead others, 1978, 1988); (2) peridotite, dunite, apparent ages of these bodies are generally and pyroxenite in Coast Mountains near Late Cretaceous (Smith and Diggles, 1981; Tracy Arm (Brew and Gybeck, 1984; Brew and others, 1984; Sutter and Gybeck and others, 1977); (3) hornblendite Crawford, 1985; Rubin and Saleeby, 1987). and pyroxene- and hornblende-bearing Unit consists of plutons on Revillagigedo gabbro on eastern Admiralty Island (Lathram Island and adjacent mainland (Berg and and others, 1965); (4) serpentinized others, 1978, 1988; Eberlein and others, peridotite or pyroxenite on north-central Admiralty Island (Lathram and others, 1985). As described above for the 1965); and (5)peridotite and serpentinite on Cretaceous granodiorite unit (Kg), some eastern Baranof lsland (Loney and others, rocks in this unit may be of Late Jurassic or 1975) of Silurian or Ordovician age Granodiorite (CretaceoustA heterogeneous KJ~ Diorite (Cretaceous and Jurassic)- suite of plutons consisting primarily of biotite, Metamorphosed and moderately deformed hornblende, magnetite + pyroxene r diorite and subordinate quartz diorite and garnet granodiorite and subordinate quartz gabbro on Annette Island, Revillagigedo monzonite, tonalite, trondhjemite, and quark Island, and mainland to northwest (Berg and diorite. On Chichagof lsland these plutons others, 1978, 1988). A small quartz diorite are associated with Early Cretaceous gabbro body near northern Annette lsland yielded a (unit Kgb) and diorite (unit Kd). Many Cretaceous potassium-argon apparent 'age; intrusive bodies show crude zoning from the other bodies are undated. We have leucocratic rocks in interior to progressively assigned a Cretaceous and Jurassic age on more mafic rocks toward margins. the basis of our interpretation that rocks in Potassium-argon apparent ages record unit are genetically related to Cretaceous and emplacement primarily during Early Jurassic volcanic (KJV) and sedimentay Cretaceous time, although similar intrusive (KJs). . rocks bodies northwest of Glacier Bay in Canada KJgb Gabbro (Cretaceous and Jurassic)-Two- also yield Late Jurassic potassium-argon pyroxene gabbro and subordinate apparent ages (Chris Dodds, oral commun., hornblende r biotite gabbro and diorite. 1984). Some bodies could also be of These intrusive rocks generally found Silurian or Ordovician age. Found on Dall adjacent to and intruded by Early Island (Gehrels and Saleeby, 1987b; G.E. Cretaceous zoned ultramafic bodies (unit Gehrels, unpub. data, 1984, Prince of Kum). Found on mainland near Myers Wales Island and adjacent smaller islands Chuck (Ruckmick and Noble, 1959; Eberlein (Eberlein and others, 1983; Brew and and others, 1983). We have assigned a others, 1984), Kuiu lsland (Brew and others, Cretaceous and Jurassic age on the basis of 1984), Admiralty lsland (Lathram and our interpretation that rocks in unit are others, 1965), Chichagof lsland (Loney and genetically related to Cretaceous and others, 1975; Johnson and Karl, 19851, Jurassic volcanic (KJV) and sedimentay north of Cross Sound (Decker and Plafker, rocks (KJS) 1982; George Plafker, written commun., Jgr Granite (Jurassic)-Peralkaline aegerine and 1984), in Glacier Bay area (Brew and others, arfvedsonite granite (Bokan Mountain 1978), and in Chilkat Range (Lathram and Granite) on southern Prince of Wales Island others, 1959; Sonnevil, 1981; Brew and (MacKevett, 1963) that yielded Jurassic Ford, 1985; MacKevett and others, 1974; potassium-argon (Lanphere and others, E.C. Robertson, written commun., 1984) 1964), uranium-lead (zircon) (Saint-Andre Diorite (Cretaceous)-Primarily hornblende 5 and others, 1983), and rubidium-strontium biotite r clinopyroxene diorite and (Armstrong, 1985) apparent ages; and an subordinate quartz diorite and gabbro. undated body of nepheline-eudialyte-bearing Generally found in association with Early syenite north of the Bokan Mountain Granite Cretaceous granodiorite (unit Kg) and (Eberlein and other;, 1983) suspected to be gabbro (unit Kgb). Found on Prince of Wales of Jurassic age Island (Eberlein and others, 1983; Gehrels Jt Tonalite (JurassictBiotite and hornblende and Saleeby, 1986, 1987a) and on tonalite and quartz diorite on Chichagof Chichagof Island (Loney and others, 1975; Island that yielded a Middle Jurassic Johnson and Karl, 1985). AS described potassium-argon (hornblende) apparent age above for the Cretaceous granodiorite unit (Loney and others, 1975) (Kg), some rocks in this unit may be of Late Jxd Diorite (Jurassic and (or) Triassick Jurassic or of Silurian or Ordovician age Hornblende and biotite diorite (Jualin ~gb Gabbro (CretaceousbPrimarily clinopyroxene Diorite) along east shore of Lynn Canal (generally augite) + hornblende + biotite (Knopf, 1911; Redman, 1984a). The diorite L olivine gabbro, leucogabbro, and a hornfelsic aureole in adjacent subordinate norite, syenite, and pyroxenite. rnetasedimentay and metavolcanic rocks of Found on Prince of Wales lsland (Eberlein probable Triassic or Permian age (unit KPsv) and others, 1983), Kuiu Island (Brew and and is overlain unconformably by less others, 1984), and Chichagof Island where it metamorphosed Cretaceous and Jurassic is associated with Early Cretaceous sedimentary rocks (KJs) (Redman, 1984a). granodiorite (unit Kg) and diorite (unit Kd) These relations suggest an emplacement age (Loney and others, 1975; Johnson and Karl, of Jurassic and (or) Triassic for the Jualin Diorite. As discussed above for Cretaceous interpreted to be Silurian on the basis of to Permian sedimentaw and volcanic rocks gradational relations with syenitic rocks of (KPsv),these relations also suggest that some Silurian age (Sst).The intrusive body on Dall rocks in the Cretaceous to Permian units lsland yielded a Late Ordovician potassium- (units KPsv, KPs, KPv, KPsvc) were argon (hornblende) apparent age (M.A. metamorphosed and deformed prior to Lanphere, written commun., 1984). An deposition of the Cretaceous and Jurassic Early Silurian potassium-argon (biotite) strata (units KJs, KJV,and KJsv) apparent age has been determined on the Igb Gabbro (TriassickTwo-pyroxene gabbro on body on east-central Prince of Wales lsland Duke Island (Irvine, 1974) and Percy Islands (Loney and others, 1987) (Berg and others, 1978, 1988) that yields SO^ Quartz diorite (Silurian and Ordoviciant a Late Triassic uranium-lead (zircon) Consists of (1) Late and Middle Ordovician apparent age (Gehrels and others, 1987) diorite and quartz diorite and Early Silurian ~g Granodiorite (Triassic)--Hornblende and biotite to Late Ordovician biotite quartz monzonite granodiorite and minor quartz diorite (part of on Prince of Wales Island (Gehrels and Texas Creek Granodiorite of Berg and Saleeby, 1987a; Eberlein and others, 1983; others, 1977) northeast of Revillagigedo Saleeby and others, 1984; Lanphere and Island (Berg and others, 1978, 1988) that others, 1964); (2) Early Silurian to Late yielded a latest Triassic potassium-argon Ordovician diorite, quartz diorite, and their (hornblende) apparent age (Smith and metamorphosed and deformed equivalents Diggles, 1981) on Gravina, Annette, and Duke Islands PPsy Syenite (Permian and (or) Pennsylvanianj- (Gehrels and others, 1987); and (3) layered Syenite on Sukkwan Island that contains and foliated quartz diorite and diorite on biotite 2 amphibole k aegerine 2 augite southern Dall Island and in small area (near and yielded potassium-argon apparent ages Ruth Bay) on southern Prince of Wales of Early Permian (hornblende) and Late Island (Gehrels and Saleeby, 1986, 1987a). Pennsylvanian (biotite) (Eberlein and others, These rocks are interpreted to be genetically 1983), This body is apparently correlative related to Early Silurian and Ordovician with syenitic plutons in the Saint Elias volcanic rocks (units SOv and SOsv) mountains region of southern Alaska that (Eberlein and others, 1983; Gehrels and yield a Late Pennsylvanian potassium-argon Saleeby, 1987a, b) (hornblende) apparent age (MacKevett and ~gb Gabbro (OrdoviciantHornblende gabbro and others, 1986) subordinate hornblende pyroxenite and Sst Syenite and trondhjemite (Silurian~onsists hornblendite on Sukkwan Island that yielded of (1) leucocratic biotite 2 aegerine 2 a Middle Ordovician potassium-argon arfvedsonite 2 garnet syenite and apparent age (Eberlein and others, 1983) subordinate leucodiorite on southern Prince and an undated metagabbro on southern of Wales Island (Gehrels and Saleeby, 1986, Dall lsland interpreted to be correlative (G.E. 1987a); (2) biotite and hornblende Gehrels, unpub. data, 1984; Gehrels and trondhjemite on Annette and Gravina Islands Saleeby, 1987b) and mainland to southeast (Gehrels and ~dg Diorite and granodiorite (CambriantFoliated others, 1987); and (3) undivided biotite and and metamorphosed hornblende diorite and (or) hornblende syenite and trondhjemite on biotite + hornblende granodiorite on east- Chichagof Island (Loney and others, 1975). central Prince of Wales Island and on Silurian age indicated by a minimum southern Gravina Island that yielded Late potassium-argon apparent age on Chichagof and Middle Cambrian preliminaw uranium- Island (Lanphere and others, 1965) and by lead (zircon) apparent ages (Gehrels and uraninum-lead (zircon) apparent ages of Saleeby, 1987b; Gehrels and others, 1987), rocks from Annette. Gravina. and Prince of and foliated and layered leucogranodiorite Wales Islands and' mainland to southeast on southern Dall Island that has yielded an (Gehrels and Saleeby, 1987a, b; Gehrels Early Cambrian uranium-lead (zircon) and others, 1987) apparent age (G.E. Gehrels, unpub. data, SOum Ultramafic rocks (Silurian and Ordoviciant 1984, Gehrels, 1984, 1987; Gehrels and Pyroxenite, hornblendite, and related Saleeby, 1987b) ultramafic rocks on southern Prince of Wales lsland (MacKevett, 1963; Gehrels and Saleeby, 1986, 1987a), on southern Dall REFERENCES CITED lsland (G.E. Gehrels, unpub. data, 1984), Armstrong, R.L., 1985, Rb-Sr dating of the Bokan and on east-central Prince of Wales Island Mountain granite complex and its country rocks: (Loney and others, 1987). Ultramafic rocks Canadian Journal of Earth Sciences, v. 22, p. on southern Prince of Wales Island are 1233-1236. Barker, Fred, 1957, Geology of the Juneau B3quad- siliferous Middle and (or) Upper Triassic rocks with- rangle, Alaska: U.S. Geological Survey Geologic in the Coast plutonic-metamorphic complex south- Quadrangle Map GQ-100, scale 1:63,360, 1 sheet. east of Skagway, in Bartsch-Winkler, Susan, ed., Barker, Fred, Arth, J.G., and Stern, T. W., 1986, Evolu- The U.S. Geological Survey in Alaska: Accomplish- tion of the Coast Batholith along the Skagway ments during 1984: U.S.Geological Survey Circu- traverse, Alaska and British Columbia: American lar 967, p. 86-89. Mineralogist, v. 71, p. 632643. Brew, D.A., and Grybeck, Donald, 1984, Geology of Berg, H.C., 1982, The Alaska Mineral Resource Assess- the Tracy Arm-Fords Terror Wilderness Study Area ment Program: Guide to information about the and vicinity, Alaska: U.S. Geological Survey Bulle- geology and mineral resources of the Ketchikan tin 15254, p. 2152, scale 1: 125,000. and Prince Rupert quadrangles, southeastern Brew, D.A., Johnson, B.R., Grybeck, Donald, Griscom, Alaska: U.S. Geological Survey Circular 855, 24 p. Andrew, and Barnes, D.F., 1978, Mineral resources Berg, H.C., Elliott, R.L., and Koch, R.D.,1988, of the Glacier Bay National Monument Wilderness Geologic map of the Ketchikan and Prince Rupert Study Area, Alaska: U.S. Geological Survey Open- quadrangles, southeastern Alaska: U.S. Geological File Report 78494, 670 p., scale 1:125,000. Survey Miscellaneous Investigations Series 1-1807, Brew, D.A., Karl, S.M., and Tobey, E.F., 1985, Re-in- scale 1:250,000, 1 sheet. terpretation of age of Kuiu-Etolin belt of volcanic Berg, H.C., Elliott, R.L., Smith, J.G., and Koch, R.D., rocks, Kupreanof Island, southeastern Alaska, in 1978, Geologic map of the Ketchikan and Prince Bartsch-Winkler, Susan, and Reed, K.M., The U.S. Rupert quadrangles, Alaska: U.S. Geological Sur- Geological Survey in Alaska, Accomplishments vey Open-File Report 78-73A, scale 1:250,000, 1 during 1983: U.S. Geological Survey Circular 945, sheet. p. 8648. Berg, H.C., Elliott, R.L., Smith, J.G., Pittman, T.L., and Brew, D.A., and Morrell, R.P., 1979, Correlation of Kimball, A.L., 1977, Mineral resources of the Gra- Sitka Graywacke, unnamed rocks of the Fair- nite Fiords Wilderness Study Area, Alaska: U.S. weather Range, and Valdez Group, southeastern Geological Survey Bulletin 1403, 151 p. and south-central Alaska, in Johnson, K.M., and Berg, H.C., and Grybeck, Donald, 1980, Upper Triassic Williams, J.R., The U.S. Geological Survey in volcanogenic Zn-Pb-Ag (-Cu-Au)-baritemineral de- Alaska: Accomplishments during 1978: U.S. posits near Petersburg, Alaska: U.S. Geological Geological Survey Circular 804-8, p. B123-B125. Survey Open-File Report 80-527, 9 p. Brew, D.A., Ovenshine, A.T., Karl, S.M., and Hunt, Berg, H.C., Jones, D.L., and Richter, D.H., 1972, S.J., 1984, Preliminary reconnaissance geologic Gravina-Nutzotin belt-significance of an upper map of the Petersburg and parts of the Port Alexan- Mesozoic sedimentary and volcanic sequence in der and Sumdum 1:250,000 quadrangles, south- southern and southeastern Alaska, in Geological eastern Alaska: U.S. Geological Survey Open-File Survey Research 1972: U.S. Geological Survey Report 84405, 43 p,, scale 1:250,000, 2 sheets. Professional Paper 800-D, p. Dl-D24. Buddington, A.F., and Chapin, Theodore, 1929, Geol- Brew, D.A., 1982, Interpretation of the heterogeneous ogy and mineral deposits of southeastern Alaska: rocks in the Duncan Canal area as a Cretaceous U.S. Geological Survey Bulletin 800, 398 p., scale melange, in Geological Survey Research 1981: 1:500,000. U.S. Geological Survey Professional Paper 1275, Burrell, P.D., 1984, Map and table describing the Admi- p. 90. ralty-Revillagigedo intrusive belt plutons in the Brew, D.A., and Ford, A.B., 1977, Preliminary geologic Petersburg 1:250,000 quadrangle, southeastern and metamorphic-isograd map of the Juneau B-1 Alaska: U.S. Geological Survey Open-File Report quadrangle, Alaska: U.S.Geological Survey Miscel- 84-171, 6 p., scale 1:250,000, 1 sheet. laneous Field Studies Map MF-846, scale Campbell, R.B., and Dodds, C.J., 1983, Geology of the 1:31,680, 1 sheet. Tatshenshini River map area, British Columbia: 1978, Megalineament in southeastern Alaska Geological Survey of Canada Open-File 926, scale marks southwest edge of Coast Range batholithic 1:125,000, 1 sheet. complex: Canadian Journal of Earth Sciences, v. Carter, Claire, 1977, Age of the Hood Bay Formation: 15, no. 11, p. 1763-1772. U.S. Geological Survey Bulletin 14354, p. A117. 1981, The Coast plutonic complex sill, south- Clark, A.L., Berg, H.C., Grybeck, Donald, and Oven- eastern Alaska, in Albert, N.R.D., and Hudson, shine, A.T., 1971, Reconnaissance geology and T.L., eds., The U.S. Geological Survey in Alaska geochemistry of Forrester Island National Wildlife Accomplishments during 1980: U.S. Geological Refuge, Alaska: U.S. Geological Survey Open-File Survey Circular 823-B, p. 896-898. Report 465, 7 p. 1985, Preliminary reconnaissance geologic Davis, Alice, and Plafker, George, 1985, Comparative map of the Juneau, Taku River, Atlin, and Skag- geochemistry and petrology of Triassic basaltic way quadrangles, southeastern Alaska: U.S. rocks from the Taku terrane on the Chilkat Penin- Geological Survey Open-File Report 85395, scale sula and Wrangellia: Canadian Journal of Earth 1:250,000, 23 p. Sciences, v. 22, p. 183-194. Brew, D.A., Ford, A. B., and Garwin, S.L., 1985, Fos- Decker, J.E., 1980, Geology of a Cretaceous subduc- tion complex, western Chichagof Island, southeast- studies in the Coast plutonic-metamorphic complex ern Alaska: Stanford, Calif., Stanford University, east of Juneau, southeastern Alaska, in Bartsch- unpublished Ph.D. thesis, 134 p. Winkler, S., and Reed, K.L., eds., The U.S. Decker, J.E., Nilsen, T.H., and Karl, S.M., 1979, Turbi- Geological Survey in Alaska: Accomplishments dite facies of the Sitka Graywacke, southeastern during 1982: U.S. Geological Survey Circular 939, Alaska, in Johnson, K.M., and Williams, J.R., eds., p. 100-102. The U.S. Geological Survey in Alaska: Accomplish- Gehrels, G.E., Dodds, C.J., and Campbell, R.B., 1986, ments during 1978: U.S. Geological Survey Circu- Upper Triassic rocks of the Alexander terrane, SE lar 804-B, p. B125-B128. Alaska and the Saint EIias Mountains of B.C. and Decker, J.E., and Plafker, George, 1982, Correlation of Yukon [abs.]. Geological Society of America rocks in the Tart Inlet suture zone with the Kelp Abstracts with Programs, v. 18, p. 109. Bay Group, in Coonrad, W.L., ed., The U.S. Gehrels, G. E., and Saleeby, J.B., 1986, Geologic map Geological Survey in Alaska: Accomplishments of southern Prince of Wales Island, southeastern during 1980: U.S. Geological Survey Circular 844, Alaska: U.S. Geological Survey Open-File Report p. 119-123. 86275, scale 1:63,360, 1 sheet. Decker J.E., Wilson, F.H., and Turner, D.L., 1980, 1987a, Geology of southern Prince of Wales Mid-Cretaceous subduction event in southeastern Island, southeastern Alaska: Geological Society of Alaska labs.]: Geological Society of America America Bulletin, v. 98, p. 123-137. Abstracts with Programs, v. 12, no. 3, p. 103. 1987b, Geologic framework, tectonic evolu- Douglas, B.J., 1986, Deformational history of an outlier tion, and displacement history of the Alexander ter- of metasedimentary rocks, Coast plutonic complex, rane: Tectonics, v. 6, p. 151-173. British Columbia, Canada: Canadian Journal of Gehrels, G.E., Saleeby, J.B., and Berg, H,C., 1987, Earth Sciences, v. 23, p. 813426. Geology of Annette, Gravina, and Duke Islands, Dutro, J.T., Jr., Armstrong, A.K., Douglass, R.C., and southeastern Alaska: Canadian Journal of Earth Mamet, B.L.,1981, Carboniferous biostratigraphy, Sciences, v. 24, p. 866481. southeastern Alaska, in Albert, N.R.D., and Hud- Grybeck, Donald, Brew, D.A., Johnson, B. R., and son, Travis, eds., The U.S. Geological Survey in Nutt, C.J., 1977, Ultramafic rocks in part of the Alaska: Accomplishments during 1979: U.S. Coast Range batholithic complex, southeastern Geological Survey Circular 823-B, p. B94-B96. Alaska, in Blean, K.M., ed., The U.S. Geological Eberlein, G.D., Churkin, Michael, Jr., Carter, Claire, Survey in Alaska: Accomplishments during 1976: Berg, H.C., and Ovenshine, A.T., 1983, Geology U.S. Geological Survey Circular 751-B, p. B82- of the Craig quadrangle, Alaska: U.S. Geological B85. Survey Open-File Report 83-91, 26 p., scale Herreid, Gordon, Bundtzen, T.K., and Turner, D.L., 1:250,000. 1978, Geology and geochemistry of the Craig A-2 Elliott, R.L., and Koch, R.D.,1981, Mines, prospects, quadrangle and vicinity, Prince of Wales Island, and selected metalliferous mineral occurrences in southeastern Alaska: Alaska Division of Geological the Bradfield Canal quadrangle, Alaska: U.S. and Geophysical Surveys Geologic Report 48, 49 Geological Survey Open-File report 81-7286, 23 p., scale 1:40,000. p., scale 1:250,000, 1 sheet. Hill, M.L., 1985a, The Coast plutonic complex near Elliott, R.L., Koch, R.D., and Robinson, S.W., 1981, Terrace, B.C.: A metamorphosed western exten- Age of basalt flows in the Blue River valley, Brad- sion of Stikinia: Geological Society of America field Canal quadrangle, in Albert, N.R.D., and Abstracts with Programs, v. 17, no. 6, p. 362. Hudson Travis, eds., The U.S. Geological Survey 1985b. Remarkable fossil locality: Crinoid in Alaska: Accomplishments during 1979: U.S. stems from migmatite of the Coast plutonic com- Geological Survey Circular 823-B, p. B115-B116. plex, British Columbia: Geology, v. 13, p. 825- Forbes, R.B., and Engels, J.C., 1970, K4"/Ar40age rela- 826. tions of the Coast Range batholith and related Himmelberg, G.R., Loney, R.A., and Craig, J.T., 1986, rocks of the Juneau ice field area: Geological Soci- Petrogenesis of the ultramafic complex at the ety of America Bulletin, v. 81, p. 5797584. Blaske Islands, southeastern Alaska: U.S. Geologi- Ford, A.B., and Brew, D.A., 1973, Preliminary geologic cal Survey Bulletin 1662, 14 p. and metamorphic-isograd map of the Juneau B-2 Hudson, Travis Plafker, George, and Dixon, Kirk, quadrangle, Alaska: U.S. Geological Survey Miscel- 1982, Horizontal offset history of the Chatham laneous Field Studies Map MF-527, scale Strait fault, in Coonrad, W.L., ed., The U.S. 1:31,6SO, 1 sheet. Geological Survey in Alaska: Accomplishments 1977, Preliminary geologic and metamorphic- during 1980: U.S. Geological Survey Circular 844, isograd map of the northern parts of the Juneau A- p. 12S132. I and A-2 quadrangles, Alaska: U.S. Geological Hutchison, W.W., 1982, Geology of the Prince Rupert- Survey Miscellaneous Field Studies Map MF-847, Skeena map area, British Columbia: Geological scale 1:31,680, 1 sheet. Survey of Canada Memoir 394, 116 p., scale Gehrels, G.E., Brew, D.A., and Saleeby, J.B., 1984, 1:250,000. Progress report on UPb (zircon) geochronologic Hutchison, W.W., Okulitch, A.V., and Berg, H.C., 1979, Geologic map of the Skeena River area, Potassium-argon ages of some plutonic rocks, British Columbia and southeastern Alaska: Geolog- Tenakee area, Chichagof Island, southeastern ical Survey of Canada Map 1385A, scale Alaska: U.S. Geological Survey Professional Paper 1:1,000,000. 525-B, p. B108-B111. Irvine, T.N., 1967, The Duke Island ultramafic com- Lanphere, M.A., MacKevett, E.M., and Stern, T.W., plex, southeastern Alaska, in Wyllie, P.J.,ed., Ul- 1964, Potassium-argon and lead-alpha ages of tramafic and related rocks: New York, John Wiley plutonic rocks, Bokan Mountain area, Alaska: Sci- and Sons, Inc., p. 84-97. ence, v. 145, p. 705-707. 1973, Bridget Cove volcanics, Juneau area, Lathram, E.H., Loney, R.A., Condon, W.H., and Berg, Alaska: possible parental magma of Alaskan-type H.C., 1959, Progress map of the geology of the ultramafic complexes: Carnegie Institute of Juneau quadrangle, Alaska: U.S. Geological Sur- Washington Yearbook 72, p, 478-491. vey Miscellaneous Geological Investigations Map I- 1974, Petrology of the Duke Island ultramafic 303, scale 1:250,000, 1 sheet. complex, southeastern Alaska: Geological Society Lathram, E.H., Pomeroy, J.S., Berg, H.C., and Loney, of America Memoir 138, 240 p. R.A., 1965, Reconnaissance geology of Admiralty Johnson, B.R:, and Karl, S.M., 1985, Geologic map of Island, Alaska: U.S. Geological Survey Bulletin western Chichagof and Yakobi Islands, southeast- 1181-R, p. R1-R48. ern Alaska: U.S. Geological Survey Miscellaneous Loney, R.A., Brew, D.A., Muffler, L.J.P., and Pomeroy, lnvestigations Map 1-1506, scale 1:125,000, 1 J.S., 1975, Reconnaissance geology of Chichagof, sheet, 15 p. Baranof, and Kruzof Islands, southeastern Alaska: Jones, D.L., Silberling, N.J., and Hillhouse, John,1977, U.S. Geological Survey Professional Paper 792, Wrangelliair displaced terrane in northwestern 105 p. North America: Canadian Journal of Earth Sci- Loney, R.A., and Himmelberg, G.R., 1983, Structure ences v. 14, p. 2565-2577. and petrology of the La Perouse gabbro intrusion, Jones, D.L., Berg, H.C., Coney, P.J., and Harris, Anita, Fainnreather Range, southeastern Alaska: Journal 1981, Structural and stratigraphic significance of of Petrology, v. 24, p. 377423. Upper Devonian and Mississippian fossils from the Loney, R.A., Himmelberg, G.R., and Shew, Nora, Cannery Formation, Kupreanof Island, southeast- 1987, Salt Chuck palladium-bearing ultramafic ern Alaska, in Albert, N.R.D., and Hudson, Travis, body, Prince of Wales Island, in Hamilton, T.D., eds., The U.S. Geological Survey in Alaska: Ac- and Galloway, J.P., eds., Geologic Studies in complishments during 1979: U.S. Geological Sur- Alaska by the U.S. Geological Survey during 1986: vey Circular 823-B, p. 6109-B112. U.S.Geological Survey Circular 998, p. 126-127. Karl, S.M., 1984, Recognition of the Burnt Island Con- MacKevett, E.M., Jr., 1963, Geology and ore deposits glomerate on the Screen Islands, southeastern of the Bokan Mountain uranium-thorium area, Alaska, in Coonrad, W.L., and Elliott, R.L., eds., southeastern Alaska: U.S. Geological Survey Bulle- The U.S, Geological Survey in Alaska: Accomplish- tin 1154,125 p. ments during 1981: U.S. Geological Survey Circu- MacKevett, E.M., Jr., Gardner, M.C., Bergman, S.C., lar 868, p. 115-1 17. Cushing, G., and McClelland, W.C.,1986, Geolog- Karl, S.M., Decker, J,E., and Johnson, B.R., 1982, Dis- ical evidence for Late Pennsylvanian juxtaposition crimination of Wrangellia and the Chugach terrane of Wrangellia and the Alexander terrane, Alaska in the Kelp Bay Group on Chichagof and Baranof [abs.]: Geological Society of America Abstracts Islands, southeastern Alaska, in Coonrad, W.L., with Programs, v. 18, no. 2, p. 128. ed., The U.S. Geological Survey in Alaska: Ac- MacKevett, E.M., Jr., Robertson, E.C., and Winkler, complishments during 1980: U.S. Geological Sur- G.R., 1974, Geology of the Skagway B3, and B4 vey Circular 844, p. 124-128. quadrangles, southeastern Alaska: U.S. Geological Knopf, Adolph, 1911, Geology of the Berners Bay re- Survey Professional Paper 832, 33 p. gion, Alaska: U.S. Geological Survey Bulletin 446, Marincovich, Louie, Jr., 1979, Miocene mollusks of the 58 p. Topsy Formation, Lituya District, Gulf of Alaska 1912, The Eagle River region, southeastern Tertiary Province, Alaska: U.S. Geological Survey Alaska: U.S. Geological Survey Bulletin 502, 61 p. Professional Paper 11252, p. C1-C14, Koch, R.D., and Elliott, R.L., 1984, Lake Oligocene Martin, G.C., 1926, The Mesozoic stratigraphy of gabbro near Ketchikan, southeastern Alaska, in Alaska: U.S. Geological Survey Bulletin 77, 493 p. Coonrad, W.L., and Elliott, R.L., eds., The U.S. McClelland, W.C., and Gehrels, G.E., 1987, Analysis of Geological Survey in Alaska: Accomplishments a major shear zone in Duncan Canal, southeastern during 1981: U.S. Geological Survey Circular 868, Alaska: [abs.] Geological Society of America p. 126-128. Abstracts with Programs, v. 19, p. 430. Lanphere, M. A,, and Eberlein, G. D., 1966, Potassium- Muffler, L.J.P., 1967, Stratigraphy of the Keku Islets argon ages of magnetite-bearing ultramafic com- and neighboring parts of Kuiu and Kupreanof Is- plexes in southeastern Alaska [abs.]: Geological lands, southeastern Alaska: U.S. Geological Survey Society of America Special Paper 87, p. 94. Bulletin 1241-C, 52 p. Lanphere, M.A., Loney, R.A., and Brew, D.A., 1965, North American Commission on Stratigraphic Nomen- clature, 1983, North American Stratigraphic Code: Redman, Earl, Retherford, R.M,, and Hickok, B.D., American Association of Petroleum Geologists Bul- 1984, Geology and geochemistry of the Skagway letin, v. 67, no. 5, p. 841-875. B-2 quadrangle, southeastern Alaska: Alaska Divi- Ovenshine, A.T., 1975, Tidal origin of parts of the Kar- sion of Geological and Geophysical Surveys Report heen Formation (Lower Devonian), southeastern of investigations R184-31. Alaska, in Ginsburg, R.N., ed., Tidal deposits: a Reed, J.C., and Coats, R.R., 1941, Geology and ore casebook of recent examples and fossil counter- deposits of the Chichagof mining district, Alaska: parts: Berlin, Springer-Verlag, p. 127-133. U.S. Geological Survey Bulletin 929, 148 p. Palmer, A.R.. 1983, Decade of North American Geol- Rossman, D.L., 1963, Geology of the eastern part of ogy ~eolo~ic~ime Scale: Geology, v. 11, p. 503- the Mount Fairweather quadrangle, Glacier Bay, 504. Alaska: U.S. Geological Survey Bulletin 1121-K, p. Plafker, George, and Addicott, W.O., 1976, K1-K57. Glaciomarine deposits of Miocene through Rubin, C.M.,and Saleeby, J.B., 1987, The inner Holocene age in the Yakataga Formation along the boundary zone of the Alexander terrane, southern Gulf of Alaska margin, in Miller, T.P., ed., Sym- SE Alaska-A newly discovered thrust belt [abs.]: posium on recent and ancient sedimentary environ- Geological Society of America Abstracts with Pro- ments in Alaska: Anchorage Geological Society, grams, v. 19, no. 6, p. 445. Anchorage, Alaska, 1976, p. Ql423. Ruckmick, J.C., and Noble, J.A., 1959, Origin of the ul- Plafker, George, and Campbell, R.B., 1979, The Bor- tramafic complex at Union Bay, southeastern der Ranges fault in the Saint Elias Mountains, in Alaska: Geological Society of America Bulletin, v. Johnson, K.M., and Williams, J.R., The U.S. 70, p. 981-1017. Geological Survey in Alaska: Accomplishments Saleeby, J.B., Gehrels, G.E., Eberlein, G.D., and Berg, during 1978: U.S. Geological Survey Circular 804- H.C., 1984, Progress in leadiuranium zircon B, p. B102-B104, studies of Lower Paleozoic rocks in the southern Plafker, George, and Hudson, Travis, 1980, Regional Alexander terrane, in Coonrad, W.L., and Elliott, implications of Upper Triassic metavolcanic and R.L., eds., The U.S. Geological Survey in Alaska: metasedimentary rocks on the Chilkat Peninsula, Accomplishments during 1981: U.S. Geological southeastern Alaska: Canadian Journal of Earth Survey Circular 868, p. 110-1 13. Sciences, v. 17, p. 681-689. Saint-Andre, Bruno de, Lancelot, J.R., and Collot, Ber- Plafker, George, Jones, D.L., Hudson, Travis, and nard, 1983, U-Pb geochronology of the Bokan Berg, H.C., 1976, The Border Ranges fault system Mountain peralkaline granite, southeastern Alaska: in the Saint Elias Mountains and Alexander Ar- Canadian Journal of Earth Sciences, v. 20, p. 236- chipelago, in Cobb, E.H., ed., The U.S. Geological 245. Survey in Alaska: Accomplishments during 1975: Savage, N.M., 1981, Lower Devonian conodonts from U.S. Geological Survey Circular 733, p. 14-16. Kasaan Island, southeastern Alaska: Journal of Plafker, George, Jones, D.L., and Pessagno, E.A., Jr., Paleontology, v. 55, p. 848452. 1977, A Cretaceous accretionary flysch and Savage, N.M.,and Gehrels, G.E., 1984, Early Devo- melange terrane along the Gulf of Alaska margin, nian conodonts from Prince of Wales Island, south- in Blean, K.M., ed., The U.S. Geological Survey in eastern Alaska: Canadian Journal of Earth Sci- Alaska: Accomplishments during 1976: U.S. ences, v. 21, p. 1415-1425. Geological Survey Circular 751-B, p. 841-844. Siiberling, N.J., Wardlaw, B.R., and Berg, H.C., 1982, Redman, Earl, 1981, The Keete Inlet thrust fault, Prince New paleontologic age determinations from the of Wales Island: Alaska Division of Geological and Taku terrane, Ketchikan area, southeastern Alaska, Geophysical Surveys Report 73, p. 17-18. in Coonrad, W.L., ed., The U.S. Geological Survey 1984a, An unconformity with associated con- in Alaska: Accomplishments during 1980: U,S. glomeratic sediments in Berners Bay area of south- Geological Survey Circular 844, p. 117-1 19. east Alaska: Alaska Division of Geological and Smith, J.G., and Diggles, M.F., 1981, Potassium-argon Geophysical Surveys Professional Report 86, p. determinations in the Ketchikan and Prince Rup- 1-4. pert quadrangles, southeastern Alaska: U.S. 1984b, Reconnaissance geology of the Mt. Geological Survey Open-File Report 78-73N. Henry Clay area, Skagway 8-4 quadrangle, Smith, J.G., Stern, T.W., and Arth, J.G., 1979, Isotopic Alaska, in Still, J.C., Stratiform massive sulfide de- ages indicate multiple episodes of plutonism and posits in the Mt. Henry Clay area, southeast Alaska: metamorphism in the Coast Mountains near Ketchi- U.S. Bureau of Mines Open-File Report 11844, kan, Alaska [abs.]: Geological Society of America scale 1:40,000, 4 sheets, 34 p. Abstracts with programs, v. 11, no. 7, p. 519. Redman, E.C.,Gilbert, W.G., Jones, B.K., Rosencrans, Sonnevil, R.A., 1981, The Chillkat-Prince of Wales D., and Hickok, B.D., 1985, Preliminary bedrock- plutonic province, southeastern Alaska, in Albert, geologic map of the Skagway B-4 quadrangle, N.R.D., and Hudson, Travis, eds., The U.S. Alaska: Alaska Division of Geological and Geological Survey in Alaska: Accomplishments Geophysical Surveys Report of Investigations 85- during 1979: U.S. Geological Survey Circular 823- 6, scale 1:40,000, 1 sheet. B, p. B112-B115. Souther, J.G., 1971, Geology and mineral deposits of Turner, D.L., Herreid, Gordon, and Bundtzen, T.K., the Tulsequah map area, British Columbia: 1977, Geochronology of southern Prince of Wales Geological Survey of Canada Memoir 362, 84 p. Island: Alaska Division of Geological and Geophys- Souther, J.G.,Brew, D.A., and Okulitch, A.V., 1979, ical Surveys Geologic Report 55, p. 11-16. Geologic map of the lskut River area, British Col- Webster, J.H., 1984, Preliminary report on a large umbia and southeastern Alaska: Geological Survey granitic body in the Coast Mountains, northeast of Canada Map 1418A, scale 1:1,000,000. Petersburg quadrangle, in Bartsch-Winkler, Susan, Streckheisen, A,, 1976, To each plutonic rock its proper and Reed, K.M.,eds., The U.S. Geological Survey name: Earth Science Reviews, v. 12, p. 133. in Alaska: Accomplishments during 1982: U.S. Sutter, J.F., and Crawford, M.L., 1985, timing of Geological Survey Circular 939, p. 116-1 18. metamorphism and uplift in the vicinity of Prince Werner, L.J., 1978, Metamorphic terrane, northern Rupert, British Columbia, and Ketchikan, Alaska Coast Mountains west of Atlin Lake, British Colum- labs.]: Geological Society of America Abstracts bia: Geological Survey of Canada Current Re- with Programs, v. 17, no. 6, p. 411. search, Paper 78-lA, p. 69-70. Taylor, H.P., Jr., 1967, The zoned ultramafic corn- Woodsworth, G.J., Crawford, M.L., and Hollister, L.S., plexes of southeastern Alaska, in Wyllie, P.J., ed., 1983, Metamorphism and structure of the Coast Ultramafic and related rocks: New York, John plutonic complex and adjacent belts, Prince Rupert Wiley and Sons, Inc., p. 96-1 18. and Terrace areas, British Columbia: Geological Survey of Canada Field Trip Guide, no. 14, 62 p.