Lexicon of Antarctic Stratigraphic Names: Introduced by Members of United States Expeditions (1972)

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Nel son LUDes tone 1 . Firs t publ ished use Schmid t , D . L . , P . L . Wi l l iams , W . H . Ne lson and J . R . Ege . Upper Precambr ian and Paleozoic s tratigraphy and s tructure of the Neptune Range , Antarc tica : USGS Prof . Paper 525-D , p . 112- 1 1 9 , 196 5 . 2 . De finit ion "The Nel son LUDes tone is here named for Nelson Peak, on the Wash­ ington Escarpment in the central par t of the Neptune Range . In the type sec t ion , 1 . 5 miles south of Nel son Peak, the Nelson LUDes tone unconformably over l ies the Patuxent Formation with a bedd ing d is­ cordance of near ly 90 ° , and is in turn over lain by a fel s ic s i l l . The contact of the conformably over lying Gambacor ta Formation is ex­ posed on the nor thwes t slope of We ins Peak ." . (Schmidt and others , 114) 3 . Type sec tion a . Location 1 . 5 miles south of Ne lson Peak, central Neptune Range , Pensacola Mountains , 83 °42 1 S , 55 °08 1 W . b . Thickness 600 - 800 feet in Neptune Range c . Lithology 5 members 1) basal red quar tz- fragment conglomerate , 1 - 20 feet 2) local red bed c l astic success ion, 60 fee t 3) lower gr ay l imes tone which cons ists of thin- bedded l imes tone containing interbedded lamellae of 1 � shale- -ool itic , p isol itic , nodular 4) middle g�B y l imes tone , 200 - 300 fee t , chick- bedded , mass ive c ommonly bleached white by al teration , 5) upper gtB y l imes tone , 100 - 1 50 feet , thin- bedded l imestone and shaly l imes tone--ool itic , p isol itic , nodular d . Relat ion to other units Over l ies Patuxent Format ion unconformably OVerlain conformably by Gambacor ta Formation e . Evidence for age "Three d ifferent faunal assemblages of tr ilobites and brachio­ pods from member 3 are of Midd le Cambr ian age , and one - 90 -

spec �en from local ly der ived talus contains an archaeocythid of probably Ear ly Cambr ian age . " Neuy Glacier Island g abbro 1 . First publ ished us e Nichols , R . L . Bedrock geology of Marguerite Bay area , Palmer Peninsula , Antarctica : Ronne Ant . Res . Exped . Tech . Rept . 13 , Office of Naval Research , Wash ington , D . C . , 60 pp. , 1955 . 2 . Definit ion "Gabbro is the country rock at the western end of Neny Glacier Ialan� There are several varieties of the gabbro , as it varies in s ize as well as mineral compos ition . " (Nichols , SO) 3. Type section a. Location Neny G lacier Island , Antarctic Peninsula b . Lithology Variable grain s ize and compos ition. Typically 40� plagioclas e , cloudy and kaolinized , 55% amphibole , 5 % pyrite , magnetite , biot ite . c . Relation to other units Intrudes Neny Is land Schis t Associated with Black Thumb MOuntain ultramafic rock Neny Island Schist 1 . Firat published use Nichola , R. L. Bedrock geology of Marguerite Bay area, Palmer Peninsula , Antarctica : Ronne Ant . Rea . Exped . Tech . Rept . 13 , Office of Naval Research , Washington, D . C . , 60 pp . , 1955. 2 . Definit ion "The Neny Island Schist is the oldes t formation in the area . It is found on Neny Is land as well as S tonington Is land , Black Thumb Mountains , Breccia Island (unofficial name) , Skua Gull Is land (unofficial name ) , and Roman Four Mt . " (Nichola , 46) - 91 -

3 . Type sect ion a . Location Neny Island, Ant arctic Peninsul a b . Lithology F i ne - to aed ium-grained hornb lend e s chis t , 60% hornb lend e , pyroxene , 2 generations of plagioclase . Invaded and included by granit ic gneiss . c . Relat ion to other units Intruded by Roman Four MOuntain Gneiss Neptune Group 1 . First published us e Williams , P . L. Petrology of Upper Precambrian and Paleozoic sands tones in the Pensacola MOuntains , Antarctica : Jour Sed . Pe� 39 , p . 1455 •146 5 . 2 . Definition "The Neptune group of early to middle( ? ) Paleozoic age is more than 1500 m. thick and cons is ts mostly of pink , buff , and l ight -green sands tones ; the group is separable into four format ions . " (Williams , 1459 } 3 . Type sect ion a. Location Neptune Range , Pensacola MOuntains b . Thicknes s 1500 m. + c . Lithology Well-sorted medium-grained sands tone , good bedding ; well-sorted and well�rounded quartz ite - 92 -

d . Relation to other units Overlies Wiens Formation unconformably Overlain by Dover Sandstone 4 . Remarks Neptune Group contains Beiser Sandstone - quart•ite Elbow Formation - red shale & s iltstone and aray sandstone Elliott S andstone - calcareous aandatone and conalomarate Brown Ridae Conalomarate 5 . Evidence for aae Paleo•oic , probably Devonian or older, baaed on paleob ,tanical evidence ( Schopf , 1968 ) . Younaer than Cambrian Nelson Limaatone . Neptune Ranae fels ic rock 1 . Fira t pUblished use Schmidt , D . L . , P.-L. WU liua , . w . a . · �eleaoa ad � . a . :z,.e. Upper Prec.mbrian and Paleo•oic atratiarapby and structure of the Neptune Rani•• Antarctica : USGS Prof Paper 525•D , p. 112 · 1-19 . 1965 . 2 . Definit ion "Fels ic rock in a s ill , about 300 feet thick , and a plus , about 100 feet in diameter , vas intruded in the Patuxent Format ion in the wa tern pert of the Neptune Raqe . The fe lsic rock il younaer than the encloaina Patuxent rocks ; and because the rock il inteuaely deformad parallel to reaional trends , it is at least older than the tima of fold:l.na of the second sequence . " (Schmidt and othe2� , 116•117 ) 3 . Type section a. Locat ion Western Neptune Ranae , Pensacola MOuntains , 83° 20 1 s , 57°00 1 w . b . Thickness 300 feet · c . Litholoay Felsic intrua iv. - 93 •

d . Relat ion to other units Intrudes Patuxent Formation e . Evidence for age Probably older than orogeny deforming second seqt�nce , Which Schuddt dates at 510 ± 30 m. y . Neptune Range lavas and flows 1 . Firs t publ ished use Schuddt , D . L . , P . L . Wi l l iaml , W . H. Ne lloR . and J . R .· Ege . Upper Precambrian and Paleozoic s tratigraphy and structure of the Neptune Range , Antarctica : USGS Prof Paper 525 -D , p . 112-119 , " 196 5 . 2 . Definition " Pillow lavas and basalt flows aggregating at least several thousand feet in thickness are interlayered with sands tone and a late of the Patuxent Formation in the wes tern part of the Neptune Range . The age of the lavas and flows is the same as that o f the enclos ing Patuxent strata - probably late Precambrian. " (Schmidt and others , 116 ) 3 . Type section a. Location Western Neptune Range , Pensacola MOuntains , 83° 20 1 S , 57 °00 1 W. b. Thicknes s Several thousand feet c. Lithology Pillow lavas and flows d . Relation to other units Enclosed in Patuxent Formation e . Evidence for age Upper Precambrian - 94 -

Neptune Range rhyolitic porphyry 1 . First published use Schuddt , D . L . , P . L. Wi l l iame , w. H. Ne l eoo , J . R. Ege. Upper Precambrian and Paleozoic s trat igraphy and structure of the Neptune Range , Antarctica : USGS Prof Paper 525 -D , p . 112-119 , 196 5 . 2 . Definition "Hypabyssal rhyolitic porphyry , in s ills as much as a thous and feet thick and in irregular shaped bodies as much as 5 Ddles across , intruded rocks as young as the Wiens Format ion in the Neptune Range . The porphyry is younger than the Wiens Formation and older than the Brown Ridge Conglomerate which contains cobbles of the porphyry . " (Schuddt and others , 117 ) 3 . Type section a. Location Central Neptune Range , Pensacola MOuntains , 83°40 ' s , 55° OO ' w . b . Thickness One thousand feet maximum c . Lithology Rhyolitic porphyry d . Relation to other units Intrudes Wien Format ion and older units . e . Evidence for age Probably lower Paleozoic New MOuntain sandstone 1 . First published use Hamilton, w . ; . Hayes , P .T . Type section of the Beacon Sandstone of Antarctica : USGS Prof Paper 456 -A , p . 1·18 , 1963 . - 95 -