<<

U.S. DEPARTMENT OF THE INTERIOR GEOLOGIC INVESTIGATIONS I–2543 U.S. GEOLOGICAL SURVEY Pamphlet accompanies map

30' 30' R 22 W 152°00' R 21 W R 20 W R 19 W R 18 W R 17 W151°00' R 16 W R 15 W R 13 W 150°00' R 11 W R 10 W 30' R 9 W R 8 W 149°00' R 6 W R 5 W 30' R 4 W R 3 W 148°00' R 1 W R 1 E 30' CORRELATION OF MAP UNITS LIST OF MAP UNITS POSTACCRETION COVER DEPOSITS PLUTONIC ROCKS POSTACCRETION COVER DEPOSITS Qs Surficial deposits () ree Qv Quaternary Be C k aver Qv Volcanic rocks (Quaternary) Qs Quaternary Thd Hornblende dacite () T 6 N QUATERNARY Tvs T 6 N Volcanic and sedimentary rocks () Thd Pliocene Tn Nenana Gravel (Pliocene and )

Tn Pliocene TKs Sedimentary rocks (Miocene to Late ) and Miocene Tu Usibelli (Miocene to )

Tmg Mount Galen Volcanics of Decker and Gilbert (1978) (early Oli-

CENOZOIC Tvs gocene and late Eocene) Miocene Tv Tu Early TERTIARY Volcanic rocks ( to ) 15' to Eocene 15' Miocene to Tmg Oligocene TKs Late and late Cantwell Formation (Paleocene and ) Oligocene Tcv Cretaceous Eocene Oligocene Volcanic rocks (Paleocene) Tgr to Tcv Tv to Paleocene TKcs Sedimentary rocks (Paleocene and Late Cretaceous) Paleocene Paleocene Paleocene Kv Volcanic rocks (Late Cretaceous) TKcs TKgr and Late Paleocene Late Kv Cretaceous and Late Cretaceous Kgr Cretaceous PLUTONIC ROCKS T 4 N Cretaceous Tgr Granitic rocks (Oligocene to Paleocene) T 4 N CRETACEOUS ACCRETED TERRANES TKgr Granitic rocks (Paleocene and Late Cretaceous) Baldry and Ruby terranes, undivided Kgr Granitic rocks (Cretaceous) ? ? ACCRETED TERRANES Baldry and Ruby terranes, undivided Permian(?) to Middle PDa Argillaceous rocks (Permian? to Middle or Late ?) T 3 N PDa or Late PDs Permian(?) to T 3 N Devonian(?) Devonian(?) PDs Schistose rocks (Permian? to Devonian?) DSl Limestone, dolomite, greenstone, schist, and (Devonian and ? ) ? DEVONIAN DOl Limestone, dolomite, greenstone, and schist (Devonian, Silurian, Devonian and ?) ? and DSl |c Clastic rocks (middle and early ?) Silurian Devonian, PALEOZOIC DOl Silurian, and SILURIAN SOvs Volcanic and sedimentary rocks (Silurian and (or) Ordovician) 65°00' Middle Ordovician(?) Silurian 65 00' ° |c and early |=sq Late SOvs and (or) Schist, quartzite, phyllite, and slate (early Paleozoic and Precam- Paleozoic(?) Oc Ordovician brian) Ordovician ORDOVICIAN Oc Chert (Late Ordovician) ? Early Dillinger terrane |=sq Paleozoic DOsa Sandstone, argillite, and limestone (Middle Devonian to Ordovician) ? and Livengood terrane Dq Quail unit (Late Devonian) T 1 N Dt Troublesome unit (Devonian?) T 1 N PRECAMBRIAN Dc Cascaden Ridge unit (Middle Devonian)

Dillinger terrane Livengood terrane Manley terrane SZa Amy Creek unit (Silurian? to Late ?)

Old Livengood Dome Chert (Late Ordovician) Cretaceous CRETACEOUS KJcs and Late(?) _Zum Ultramafic and mafic rocks (Early Cambrian and (or) Late Proterozoic) T 1 S Manley terrane T 1 S ? KJcs Clastic sedimentary rocks (Cretaceous and Late? Jurassic) JURASSIC

AND MESOZOIC }|p Phyllite, schistose phyllite, quartzite, siltite, amphibolite, diorite, and greenstone (Mesozoic or Paleozoic) _Zsp Serpentinite and mafic rocks (Early Cambrian and (or) Late Pro- Mesozoic terozoic) }|p or 45' Paleozoic PERMIAN McKinley and Pingston terranes, undivided 45' TO KJf MISSISSIPPIAN Flysch ( and ) ^bd Basalt, diabase, gabbro, and subordinate interbedded sedimentary Late ? Dq rocks (; and Karnian) Devonian Dt Devonian(?) Middle Dc DEVONIAN ^cs ? Devonian Calcareous sedimentary rocks (Late Triassic; Norian and Karnian) ^*s ? Flysch-like sedimentary rocks (Late Triassic to Pennsylvanian)

SILURIAN Dy DOsa Middle Yanert Fork sequence (Late Devonian) Devonian to PALEOZOIC Ordovician Minook terrane Late Old ^c T 3 S Ordovician Black shale and chert (Triassic) Silurian(?) ORDOVICIAN T 3 S SZa to Late Ps Sedimentary rocks (Permian) Proterozoic(?) Early Early Nenana terrane Cambrian Cambrian CAMBRIAN _Zum and (or) _Zsp and (or) ^sc Sedimentary calcareous rocks (Late Triassic) Late Late Proterozoic Proterozoic Nixon Fork and Minchumina terranes, undivided ? Dls Limestone and siltstone (Late? Devonian) PROTEROZOIC T 4 S McKinley and Pingston terranes, undivided Minook terrane Nenana terrane DOc Chert (Early Devonian to Ordovician) T 4 S DOs Shaly rocks (Early Devonian to Ordovician) Early Cretaceous CRETACEOUS KJf and |ma Late Jurassic Mudstone, argillite, grit, quartzite, calcareous quartz-chert are- JURASSIC nite, sandy limestone, and minor chert and quartz-mica schist (early Paleozoic?) Late Late 30' ^bd ^cs ^sc Triassic Triassic MESOZOIC 30' ^c Triassic TRIASSIC Seventymile terrane PMum Ultramafic and mafic rocks (Early Permian? to Mississippian?) T 5 S Late Triassic ^*s to T 5 S Tozitna terrane Pennsylvanian Ps Permian PERMIAN ^Mms Mafic igneous rocks and sedimentary rocks (Triassic to Mississippian)

White Mountains terrane, Wickersham terrane, and PENNSYLVANIAN Yukon-Tanana terrane north of Tanana River, undivided ^m

PALEOZOIC Mafic igneous rocks (Triassic) MISSISSIPPIAN Late Mg Globe unit (Mississippian) Dy DEVONIAN T 6 S Devonian M_bh Hill sequence (Mississippian to Cambrian) T 6 S Nixon Fork and Minchumina terranes, undivided Seventymile terrane Tozitna terrane M_cr Chena River sequence (Mississippian to Cambrian)

Dcg Conglomerate, graywacke, and slate (Devonian?)

TRIASSIC DSt Tolovana Limestone (Middle Devonian to Early Silurian)

MESOZOIC |cs Chert and siliceous shale (early Paleozoic)

T 7 S ^Mms Triassic to PERMIAN |ch Chatanika unit (early Paleozoic) ? Mississippian Of Creek Volcanics (Late to Early Ordovician) T 7 S Early Permian(?) PMum PENNSYLVANIAN to Mississippian(?) _Zwa Wickersham unit (Early Cambrian and Late Proterozoic)

? MISSISSIPPIAN Zwg Grit (Late Proterozoic) 15' ? Late(?) 15' Dls Zf Fairbanks schist unit (Late Proterozoic) ? Devonian DEVONIAN Yukon-Tanana terrane south of Tanana River T 8 S MDt Totatlanika Schist (Early Mississippian to Middle Devonian) ? PALEOZOIC T 8 S SILURIAN Early Devonian Dms Metasedimentary rocks (Late or Middle Devonian) DOc DOs to Ordovician Dmg Metagabbro (Late Devonian?) Early |ma ORDOVICIAN |kp Keevy Peak Formation (early Paleozoic) Paleozoic(?) |=s Pelitic and quartzose schist (early Paleozoic and (or) Precambrian) CAMBRIAN T 9 S Contact—Dashed where inferred; dotted where concealed; queried where doubtful ?

T 9 S Fault—Dashed where inferred; dotted where concealed; queried where doubtful White Mountains terrane, Wickersham terrane, and Strike-slip fault—Arrows show relative horizontal movement Yukon-Tanana terrane north of Tanana River, undivided U Fault—U, upthrown side; D, downthrown side D Thrust fault—Sawteeth on upper plate ^m Triassic TRIASSIC High-angle reverse fault—Sawteeth on upper plate MESOZOIC T 10 S PERMIAN Fold—Showing crestline and plunge. Dashed where inferred; dotted where con- AND T 10 S cealed; queried where doubtful PENNSYLVANIAN Anticline

Mg Mississippian MISSISSIPPIAN Syncline 64°00' 64°00' ? Strike and dip of beds

Dcg Devonian(?) DEVONIAN Inclined

? Vertical Middle Devonian DSt to Early Silurian T 11 S Strike and dip of foliation M_cr Missippian SILURIAN

M_bh PALEOZOIC T 11 S to Cambrian Inclined

Vertical Late to Early Of |cs |ch Early ORDOVICIAN Ordovician Paleozoic Drill hole

Gravity contours—Contour interval 5 milligals. Hachured contours show CAMBRIAN closed areas of relatively lower gravity. X is control point Early _Zwa Cambrian T 12 S

T 12 S 152° 150° 148° Zwg Late TZ LG TZ Proterozoic { MNK BRY-RB Zf

PROTEROZOIC MAN WHM-WS-YTN

Yukon-Tanana terrane south of Tanana River 65°

T 13 S MISSISSIPPIAN T 13 S Early Mississippian ? MDt Dmg Late to Middle Devonian Dms Late or Middle Devonian ? Devonian(?) DEVONIAN TKcs 45' 45' TKcs TKcs SILURIAN SV TKcs { TKcs NX-MN TKcs

TKcs PALEOZOIC |kp Early T 14 S ORDOVICIAN TKcs TKcs Paleozoic YTS T 14 S Early Paleozoic 64° TKcs |=s YTS and (or) CAMBRIAN Precambrian TKcs YTS TKcs YTS MK-PN TKcs TKcs MK-PN TKcs TKcs NN T 15 S DL PRECAMBRIAN

TKcs TKcs TKcs 0 25 50 75 100 KILOMETERS T 15 S TKcs

TKcs 0 50 MILES TKcs TKcs TKcs TKcs TERRANE MAP Map of study area showing lithotectonic terranes of the Nenana basin area TKcs 153° 150° 147° TKcs 66° of central Alaska. Adapted from Jones and others (1987) and Silberling and ALASKA Jones (1984). TKcs T 16 S TANANA LIVENGOOD EXPLANATION TKcs 152°05' 147°26' 65°25' { T 16 S TKcs E deposits TKcs G 1 2 BRY-RB Baldry and Ruby terranes, undivided N TKcs 30' 30' 65° DL Dillinger terrane A 4 TKcs A LG Livengood terrane TKcs K R KANTISHNA RIVER FAIRBANKS MAN Manley terrane A L A S TKcs MK-PN McKinley and Pingston terranes, undivided TKcs EXPLANATION 3 5 6 1 Chapman and others (1982, 1975a) MNK Minook terrane R 23 W R 22 W R 21 W R 20 W R 19 W R 17 W R 16 W R 15 W R 14 W R 12 W R 11 W R 9 W R 8 W R 7 W R 6 W R 4 W R 3 W R 2 W R 1 W R 1 E 152°00' 30' 151°00' 30' 150°00' 30' 149°00' 30' 148°00' INTERIOR—GEOLOGICAL SURVEY, RESTON, VA—2001 30' 2 Chapman and others (1971); Weber 64° NN Nenana terrane and others (1992) Base from U.S. Geological Survey, Fairbanks, 1956 (rev. 1976); SCALE 1:250 000 Bedrock geology compiled by Gina M. Frost in 1993 1 NX-MN Nixon Fork and Minchumina terranes, undivided 24 /2 ° 3 Chapman and Yeend (1981); Chapman Healy, 1956 (minor rev. 1981); Kantishna River, 1952 (limited from sources shown on Index Map. Isostatic gravity 787 9 505110 520 MILES ALASKA and others (1975b) SV Seventymile terrane rev. 1983); Livengood, 1956 (rev. 1977); Mt. McKinley, 1958 compiled by David F. Barnes 4 Chapman and others (1975a) (limited rev. 1982); Tanana, 1960 (rev. 1976) 63°27' TZ Tozitna terrane 5501015202530 KILOMETERS Edited by Jan L. Zigler; layout and design by Kevin 5 Chapman and Yeend (1981) Universal Transverse Mercator projection NORTH Ghequiere and Susan Mayfield; digital cartography 6 Péwé and others (1966); Robinson and MT MCKINLEY HEALY WHM-WS-YTN White Mountains terrane, Wickersham terrane, and Yukon- by Richard Koch NETIC TRUE NORTH CONTOUR INTERVAL 200 FEET others (1990) Tanana terrane north of Tanana River, undivided MAG DASHED OR DOTTED LINES REPRESENT 100-FOOT CONTOURS Manuscript approved for publication March 6, 1995 7 Reed (1961) 63° YTS Yukon-Tanana terrane south of Tanana River APPROXIMATE MEAN MAP LOCATION DECLINATION, 2001 NATIONAL GEODETIC VERTICAL DATUM OF 1929 8 Jones and others (1983) 9 Csejtey and others (1992, 1986)

INDEX MAP SHOWING PRIMARY SOURCES OF GEOLOGIC MAPPING AND 1:250,000-SCALE QUADRANGLES GEOLOGIC AND ISOSTATIC GRAVITY MAP OF THE NENANA BASIN AREA, CENTRAL ALASKA

By Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Geological Survey Gina M. Frost, David F. Barnes, and Richard G. Stanley For sale by U.S. Geological Survey, Map Distribution, Box 25286, Federal Center, Denver, CO 80225, 1–888–ASK–USGS Printed on recycled paper 2002 Available on World Wide Web at http://geopubs.wr.usgs.gov/i-map/i2543/