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and 40178 have a bigger crustal signature ana rnus are more like CAB and CTB. With more geochemical &ts and some warranted scepticism, the RBE patterns and trace-elment chemistry of orthoamphibolite of the Yukon-Tanana Upland, together with more detailed field mapping of these rocks, may provide valuable information about the tectonic history of this enig- matic terrane. REFERENCES CITED Aleinfkoff, J. N., DuseL-Bacon, Cynthia, Poster, H. L., and Futa, Kiyoto, 1981, Proterozoic zircon from augen gneiss, Yukon-Tanana Upland, east-central Alaska: Geology, v. 9, no. 10, p. 469-473. AIeinikoff, J. N., Foster, H. L., Nokleberg, W. J., and Dusel-Bacon, Cynthia, 198 5, Isotopic evidence from detrjtal zircons for Early Proterozoic crus tal material, east-central Alaska, Cobnrad, W. L., and Elliott, R L., eds., The United States Geologfcnl Survey In Alaska-Aecomplishments during 1981: U.S. Geological Swey Circular 868, p. 43-45. Arth, J. G., 1981, Rareearth element geochemistry of the island-an! volcanic rocks of Rabaul and Telasea, New Britain: Geological Society of America Bulletin, v. 92, no. 11, p. 858463. Barth, T. F. W., 1962, Theoretical petrology (2d ed.): New York, John Wiley, 416 p. Evens, B. W., and Leake, B. B., 1960, ?he composition and orldn of the striped amphibolites of Comemafa, Gelend: ~ournk of ~etrology, v. 1, no. 3, p. 337-363. Frey,-F. A., Heskln, M. A., Poeb, 3. A., and Baskin, L A., 1968, Rare earth abundances in some besic rocks: Journal of Geophysical Researah, v. 73, no. 18, p. 6085-6098. GareIe, M. O., 1978, Criteria for the identifioation of ancient volcanic arcs: Earth Scfence Reviews, v. 14, no. 2, p. 147-165. Gottfried, !kvid, Annell, C. S., and Sehwarz, L. J., 1977, Geochemistry of subsurface basalt from the deep corehole (Clubhouse Crossroads corehole 1) near Charleston, South Carolina-magma type and tectonic implications: U.S. Geological Survey Professional Paper 10284, Q. 91-113. Hasun, L. A,, Frey, P. A., Schmitt, R. A, and Smith, R. H., 1966a, Meteoritic, solar, and terrestrial rare-eerth distributions, & hhrens, L. H., Press, Prank, Runcorn, S. R., and Urey, K C., eds, Physics and chemistry of the earth: New York, Pegamon, p. 167-321. Haskin, L. A., Wildeman, T. R, Prey, F. A,, Collins, K. A., Keedy, C. R, and Hesldn, M. k, 1966b, Rare earths in sediments: Journal of Geophysical Research, v. 71, no. 24, p. 6091-6105. Leake, B. E., 1964, The chemical distinction between ortho- and para-amphibolites: Journal of Petrology, v. 5, no. 2, p. 238-254. Masuda, Akimasa, Nakamura, Noboru, and Tanaka, Tsuyoshi, 19'73, Fine structures of mutually normalized rare-earth patterns of chondritos: Ceouhimica et Cmochlmica Acta, V. 37, no. 2, p. 239-248. Noekolds, S. R., 1954, Average chemical compositions of -me lmeous rock Geolodcal Society of America ~ hetln, V. 65, no. 10,g 1007-1032; Orvllle, P. M., 1969, A mMek for metamorphic differ- entiation origin of Ulin-layered amphibolftes: American Journal of Science, v. 267, no. 1, p. 64- 86. Pearce, J. A., 1975, Basalt geochemistry used to inves- tigate past tectonic environments on Cyprus: Tectonophysics, v. 25, no. 1-2, p. 41-67. Pearce, J. A, and Can, J. R., 1973, Tectonic setting of basic volcanic rocks determined using trace element analyses: Earth and Planetary Sdence Letters, v. 19, no. 2, p. 290-300. Preto, V. A. G., 1970, Arnphibolites from the Grand Forks quadrangle of British Columbia, Canada: Geological Society of America Bulletin, v. 81, no. 3, p. 763-782. Shaw, D. M., and Kudo, A. M., 1965, A test of the dis- criminant function in the amphibolite problem: Mineralogical Magazine, v. 34, no. 268; p. 423- 435. Suen, C. J., Frey, F. A., and Malpas, J., 1979, Bay of lslands ophiolite suite, Newfoundland: Petrologic and geochemical characteristics with emphasis on rare earth element geochemistry: Earth and Planetary Science Letters, v. 45, no. 2, p. 337- 348. Metamorphi0 -1- of the 'IBhle Martlbh m, Circleqnadreagle,AZeslca By~C.WnadqJ~~,BalenL.Paatet,and I Grant W. Cuahiqg i Metamorphic rocks along Me Pinnell Mountain trail, Circle E M quadrangle, Alaska (area 3, fig. 23; flg. 321, are part of a complexly deformed terrane of schlst and quartzite of Paleozoic and (or) Precambrian age that are typical of much of the western Yukon- Tanma Upland (Poster and others, 1973). We have been studying the petrolcgy of these rocks as a regre- sentative sample of this metamorphic terrene, and this repart describes typical mlneral assemblages and presents pmbabIe conditions of metamorphism. A knowledge of the metarnorphia history may help in identifying the kind and extent of minerallaation in the Table Mountain area. The metamorphic rocks studied are divided into pefitie schist and quartzite, mnfic schist, and calc- sUlcate rocks. A northeast-trendhg lineament, dis- oernible on aerial photographs (fig. 32; CusNng and others, 19821, appears to separate rocks regionally metamorphosed to epidote-amphibolite facies (garnet grade) on the south from contact-metamorphosed rocks (biotite hornfels) on the north. The contact me mor him, which is related to a ernall (approx 2- km e are 3 granodiorfte pluton (fig. 32) has overprinted regional metamorphism of probable epidote- amphibolite f acies (gatnet grade). Several small epizonal felsic intrusions dm crop out north of the lineament, mostly in the vicinity of Table Mountain eig. 32). Pelltic rocks south of the lineament are ptlmar- Ily composed of quartz~lagioclase+muscovite+chlorite+biotIteIgarnet; the plagioclase is commonly por- phyroblastic. Coexisting with this epidote- am phiMLLte-facies assemblage, near the linae ment
& Fclsic in~rutirt rucks 0 Eio~ite homfek (sample 3 126F analyzed by electron microprobe, table 12) A Malic rocks inarcrlsted in ptlitic rocks Cak.sili&ire rocks Inlercalsted in pelitic rwks (sample 3 10SE analyzed by elrciron microprobc, rablc 12) EXPLANATION x YI - C) 2 0 .- 3 P d5 Suike and dip of [olietion - Lineament (inlerprrred from aerial photographs) * Chlo~itoid.psmec~chlori~e 0 Chbrite.yrnet-biolice a Fe.rich chlorlce FclMg ratio h chloricc 1.0 M&rich chlorite Figure 32.--Sketch map of study area, showing generalized geology and grade (biotite or garnet) of regional metamorphism in the Table Mountain area. Sample 312BF is biotite harnfels typIa of peUtic rocks along the PinneU Mountain trail northwest of Lineament. Numbers in parentheses refer to calc-silicate assemblages discussed in text. S5
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n Alas Accompli: ' I.S. GE OLOGI CA
Page 3 and 4:
I CONTENTS Page A bst raet ........
Page 5 and 6:
-- --A I ALASEU i nued rral expluru
Page 7 and 8:
........ igure .JB. ;5~ercn map ox
Page 9 and 10:
. , ".,k a. ,.e ,\a 1 y U11 IIIUUII
Page 11:
THE UNITED STATES GEOLOGICAL SURVEY
Page 15 and 16: ~ t I r n t S i m ~ ~ Alarr a ~ man
Page 17 and 18: I -1977, RelImlnary documentat!on l
Page 19 and 20: I I MaCenn, W. R., Perez, 0. J., an
Page 21 and 22: were deslgned to impMve the accurac
Page 23 and 24: Noatak Sandstom and is overlaln con
Page 25 and 26: I (Nilsen and others, 1981a); (2) f
Page 27 and 28: I that contains the Upper Devonian
Page 29 and 30: who found Westeqaardodina sp., posb
Page 31 and 32: Table 2 lists the means rtnd for th
Page 33 and 34: ' Noatak Vdley (fig. 129. This ice
Page 35 and 36: 3 EUMN OF MAP UNITS WAmWARY OUAERNA
Page 37 and 38: -om displacement of the cc tween th
Page 39 and 40: I US I Surlicial dcnrrua,ts [~dater
Page 41 and 42: I Plafker, George, Hudson, Travis,
Page 43 and 44: !omlensed iring vapors generated by
Page 45 and 46: and the thinning. -upward cycles .,
Page 47 and 48: Kellum, L. B., Devless, S. N., and
Page 49 and 50: 1912 sample (a mediumwey pumice blo
Page 51 and 52: various Utholagic units present Thu
Page 53 and 54: fault, and Its depositional basemen
Page 55 and 56: suggested by coplanar foUaticm and
Page 57 and 58: 1 slgnlficarrtly more umnlum (73&1,
Page 59 and 60: ecrSigtallized catadastic matrix of
Page 61 and 62: analyzed to determine whether Immob
Page 63: are tgplcd of both ocean-floor basa
Page 67 and 68: are Lrdlcated by coexisting @&ite+q
Page 69 and 70: (Mg3.09 pe2+ 0.69 pe 0.~1~0.01~~0.9
Page 71 and 72: westward into a narrow band that ex
Page 73 and 74: EXF'lANATIOW 66600' Contan-Apprnimn
Page 75 and 76: ! few fold closures are preserved.
Page 77 and 78: even thickness and conform to irreg
Page 79 and 80: (Alnus ap.), heaths (Ericaceae, + E
Page 81 and 82: terrane extends at least 300 krn to
Page 83 and 84: Table 19.--6tneral petrography of M
Page 85 and 86: were measured on 8 12-in. mass spec
Page 87 and 88: Thin lenses of cabonate packtone to
Page 89 and 90: The cantwell(?) Pormation south of
Page 91 and 92: in the 18 lava flows b thermoremane
Page 93 and 94: Upper Cretaceous shale in contact w
Page 95 and 96: Gran tz, Arthur, 1960, Generalized
Page 97 and 98: at 15 to 20 percent. Primary Inolus
Page 99 and 100: addition, this factor generally def
Page 101 and 102: Joreskog, K. G., Klovan, J. E., and
Page 103 and 104: Mineral qItWation end r ~ k t k W e
Page 105 and 106: 1 "~_liO-/ 200 1000 B roo C E % A B
Page 107 and 108: Smaller placer mines ere active on
Page 109 and 110: Figme 62.-Plant fassils from the co
Page 111 and 112: Hallam, Anthony, 1975, Alfred Wegen
Page 113 and 114: u ALASKA Figure 65.--Sketch map of
Page 115 and 116:
F ' i a?.-Intertidal bluffs compose
Page 117 and 118:
C-s - - Figure 70.-Products of eros
Page 119 and 120:
curve is based indicates that 6.1 c
Page 121 and 122:
sampled is related to widespread ma
Page 123 and 124:
marble is alsa locally present In t
Page 125 and 126:
Bedding in the conglomerate ranges
Page 127 and 128:
1 purpose of this study wes to dete
Page 129 and 130:
The secona k~~-~ri?tation mmes that
Page 131 and 132:
epizonb'l granitic Miss, mixed with
Page 133 and 134:
40 40 Forbes, R. B., and Engels, J.
Page 135 and 136:
foliated and inequigranular end con
Page 137 and 138:
I I thy euheclra. Sphene anhedra an
Page 139 and 140:
Quartz Alkali feldspar Plagioclase
Page 141 and 142:
F'@m 85.--Sketch map of Juneau area
Page 143 and 144:
HoUister, L. 8, 1966, Garnet zoning
Page 145 and 146:
! ~ bI8oO, (IN PERMIL) ~lqp~e 87.-8
Page 147 and 148:
Figure 90.-Offshore ereas discussed
Page 149 and 150:
Preliminerg analpsis of miemfauna f
Page 151 and 152:
Survey tn Alaekai AccompUshments hh
Page 153 and 154:
Gecllogical Survey Open-File Report
Page 155 and 156:
I provenance, and tectonia sIgnific
Page 157 and 158:
Keith, T. E. C, Barnes, Ivan, afrd
Page 159 and 160:
Open-Flle Report 8P811C, 19 p. + 2
Page 161 and 162:
United States Qeological Survey in
Page 163 and 164:
, ,. nldslra poblisbe!d by Prior, D
Page 165 and 166:
60, Alaska: Offshore Technology Con
Page 167:
Author Index [Page number underscor
Page 170 and 171:
Parks. Bruce ......................
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