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

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LaGorce Formation 1 . Firs t published use Minshew, V . H . Petrologic investigations in the area o f Scott Glacier -- Wiscons in Range : Ant . Jour . U. S . 2 , 1 . 109 - 110 , 1967 . 2 . Definition "Some of the oldes t rocks in the area are metagraywackes with a thickness es timated to exceed 3000 m. ; the beds dip vertically and s trike parallel with the mountain front . The metagraywackes have been metamorphosed to the greenschist facies where they are intruded by the typical grey granite of this area. " Minshew, v. H . Potas s ium-argon age from a granite at MOunt Wilbur , Queen Maud Range , Antarct ica : Science 150 , p . 741-743 , 1965 . 3 . Type section a . Location LaGorce MOuntains , Queen Maud Ranae b . Th ickness 3000 feet plus c . Lithology Rhythmically bedded graywacke& and phyllites which have been metamorphosed to greens chis t facies d. Relation to other units Intruded by MOunt Wilbur granite Overlain by Wyatt Format ion e . Evidence for age Specimens from the Wis cons in Range , correlated on the bas is of lithologic s imi larity with the LaGorce Format ion , yield 460 ± 16 m. y. ages by Rb -Sr . This is the age of the metamorphism, not depos ition. Faure , G . , J . G . MUrt augh and R. J . E . MOnt igny. The geology and geochronology of the basement complex of the central Trans -antarct ic Mountains : Can Jour Earth Sci 5 (3 , pt 2) . P • 555 -560 , 1968 . - 60 -

Lassi ter Coast plutonic rocks 1 . First pub l ished use Wi lliams, P . L . , D . L . Schuddt , C . C . Plummer , and L . E . Brown . Geology of the Lass i ter Coast area , Antarct i c Peninsula , a pre liminary repor t : Proc . Symp . on Antarct ic Geol . and Geophysi cs, Oslo ( in preparat ion ) 2 . De finit ion " I n the area exp lored to d ate , about a dozen plut ons 5 - 15 km are exposed . " 3 . Type se c t ion a . Locat ion Latady MOuntains , Sci afe Mount ains, Rare Range , lat . 74° 40 ' S , long . 64° w . b . Li tho logy " • • • range in composi tion f is) from granite to granod iorite . " c . Re lation t o other units Intrude Latady Format ion d . Evidenc e for age Cre t aceous , based on analogy with rocks of e astern E llsworth Land (Laudon et al , 1969 ; Halpern , 196 7 ) . Latady Format ion 1. First published use Wi lliams , P. L. , D. L . Schmidt , C . C. Plummer , and L. E . Brown . Geology o f the Lass iter Coas t area, Antarctic Peninsula , a . pre liminary report : Proc . Symp . on Ant arctic Geo l . and Geophys ics , Oslo ( in preparation) . 2 . De fin i t ion "The se rocks are herein named the Lat ady Format ion , after the Lat ady Mountains where they are extens ively exposed . " - 6 1 -

3 . Type sect ion a. Location 4 km north of McLaughlin Peak , Latady Mountains , Lass iter Coast lat . 74° 3 5 1 S , 64° 15 1 w. b . Lithology Black carbonaceous marine s iltstone and shale with minor thin volcanigenic lithic graywacke& . Rocks are tightly folded with well developed axial plane cleavage . c . Thickness 600 m + at type locality ; total thickness probably several thousand meters . d . Relation to other units Intruded by Lass iter Coast plutonic rocks ; overlain by Mt . Poster volcanics e. Evidence for age Kimmeridgian (middle late Jurass ic) baaed on an ammonite and pelecypod , ace . to R. W . Im!ay , U . S . Geo l . Survey. 4 . Correlat ives Jurass ic rocks in eas tern E llsworth Land (Laudon , 1969 ) Lateral Moraine Pluton i . Firs t published use Nichols , R. L . Bedrock geology of Marguerite Bay area , Palmer Peninsula, Antarct ica : Ronne Ant . Rea . E�d . Tech . Rept . 13 , Office of Naval ResearCh , Washington , D. c. , 60 pp . , 19 55 . 2 . Definit ion "The Lateral Moraine Pluton ia found at Neny Fjord 'I.'h\lld) (unofficial name ) , on the ridge which runs northeast from the Companion Tb\Jld) (unofficial name) , and on the south a ide of Neny Fjord . " (Nichola , 54-55 ) 3 . Type section a . Location Neny Fjord area - 62 -

b . Lithology Porphyry grades from coarse -grained center to pir� fels ite at contacts . 50% feldspar phenocrys ts , quartz in groundmas s , abundant hornblende . Compos ition andes itic . c . Relat ion to other units Poss ible intrus ive equivalent of Terra Firma Volcanics Legoupil Formation 1 . Firs t published use Halpem , M. The Geology of the General Bernardo O 'Higgins area , Northwes t Antarctic Peninsula : Geology and Palecntology of the Antarct ic , Ant . Res . Ser . Vol . 6 , p . 177-209 , 196 5 . 2 . Definition "The Legoupil Formation , named for Cape Legoupil , includes the clas t ic sedimentary rocks that crop out at Cape Legoupil and on the is lands and along the coast of the Duroch Is lands . " (Halpern , 180 ) 3 . Type section a. Locat ion Cape Legoupil ( 63 ° 20 ' S , 57 ° 53 1 W) , Base Bernardo O 'Higgins of the Trinity Peninsula , Antarct ic Peninsula b . Thickness Minimum 4000 feet c . Lithology Argillite , quartzwacke , quartz -feldspathic wacke , quartz •feldspathic arenite , arkos ic arenite , granule to pebble conglomerate and pebbly mudstone . MOs tly fine sand to clay s ize , feldspathi� thick s trat ification , unsorted , non-graded . d . Relation to other units Intruded by Early Cretaceous plutonic intrus ive suite - 63 -

e . Evidence for age K•Ar age of 116 ± 4 m. y . from diorite pebble in pebbly Dllds tone gives an older age limit . K-Ar age o f 74 . 7 ± 2 . 8 m. Y• from pyroxene in an andes ite dike cutting the dated mudstone seta a younges t possible age . Halpern , M. Cretaceous sedimentation in the "General Bernardo O ' Higgins" area of north -wes t Antarctic Pen insula : Lepley granitoid rock Antarctic Geolo� , Proc . Ca�town Symp . 1963 , John Wiley and Sons , 1964 , p . 336 . 1 . First publ ished use Craddock, c. , c.M. Whi�e a�d R . H� Rutford. The geology of E ights Coast : Ant . Jour . u . s. 4 , p . 93-94 , 1969 . 2 . Definit ion "Lepley Nunatak cons ists _ . of a mas s ive , ligh t gray granitoid rock , epidotized along joint surfaces and cut by numerous mafic dikes ." (Craddock et al , 93) 3 . Type sect ion a . Location Lepley Nunatak , Eights Coast Leverett Format ion 1 . Fira t published use Minshew, v . H. Petrologic inves tigat ions in the area of Scott Glacier • • Wis cons in Range : Ant . Jour . U. S . 2 , p. 109 -110 , 1967 . 2 . Definit ion "North o f Watson Escarpment in the area of the Leverett Glacier , the gray granite intrudes thick , more gently dipping , slightly metamorphosed carbonates , sandstones and rhyolites . Thes e beds of the Leverett group contain thin beds of carbonate riCh in trilobite fragments that appear to be of Camrian age . " - 64 -

Minshew , v. H . Potass ium-argon age from a granite at MOunt Wilbur , Queen Maud Range , Antarct ica : Science 150 , p . 741 -743 � 196 5 . 3 . Type section a. Locat ion Leverett Glacier north of Watson E scarpment , Queen Maud Range b . Th ickness 1500 meters of carbonate rocks c . Lithology Me tamorphosed carbonate rocks wi th tr i l ob i te s , sand s tones , and rhyo l i te s d . Re l a t ion to o ther un i t s Intruded by Moun t Wi l bur gran i te . Over l ies LaGorce and Wya t t Forma t i on wi th angul ar uncon formi ty e . Evidence for age "con tains Midd le Cambr ian tr i l ob i te fauna • . . " Minshew , V . H . Pe trologic inve s t igations in the area of Scot t G l ac ier -- Wiscon s in Range : An t . J our . U . S . 2 , p . 1 10 , 1 96 7 . L i t t lewood dac i te 1 . F ir s t pub l i shed use Louns bury , R. W . , N . B . Aughenbaugh , J . C . Behrend t . P e trology o f the Li t t l ewood Nunataks near Vahsal Bay , Antarc t ica : GSA S pec . Pap . 73 , p . 1 98 , 1 962 . 2 . De fin i t ion "The Li t t l ewood nunataks c ompr i se dark- red porphyr i t ic lavas cons i s t ing of ol igoc l ase phenocrys t s , 1 - 2 mm l ong , in a very f ine- grained groundmass of fe ldspar , hemat i te and some msgne t i te . The only other dark mineral is iron oxide in tabu l ar crys tal s , wh ich appears to have been der ived from the a l ter a t i on of b i ot i te . The l a t ter cons t i tutes leas than 5 per cen t of the r ock . Numerous ve inl e t s of chalcedony traverse the matr ix . The rock tentat ive ly iden t i f ied as dac i te , i s s tr iking ly s imi l ar to the l avas col lec ted by the Falkl and I s l and Dependency Survey from the Palmer Pen insu l a , We s t An tarc t ica . " (Louns bury , Aughenbaugh , Behrend t , 1 98 . ) - 6 5 -

3 . Type section a . Locat ion Littlewood Nunataks near Vahs al Bay at the eas t end of the FilChner Ice Shelf . 4 . Synonym& or closely related names See Littlewood Volcani cs 5 . Remarks "The compos it ion of the rock is cons idered s ignificant s ince it is not typi cal of East Antarct ica , but show affinities to the Andean Suite . " (Lounsbury , Aughenbaugh , Behrendt , 198 ) Littlewood Volcanics 1. Firs t published use Aughenbaugh , N . B . , R . W . Lounsbury , J. C . Behrend t . The Litt lewood Nunataks , Antarct ica : Jour . Geol . 73 , p . 889 -894 , 196 5 . 2 . Definit ion "Saqlles of rock collected at Litt lewood Nunataka in Coats Land have been ident ified as rhyolite porphyries and des ignated the Littlewood Volcanics . " (Aughenbaugh et al, 893 ) 3 . Type sect ion a . Location Littlewood Nunataks , Coats Land (77° 53 . 5 1 S , 34° 10 ' W) b . Lithology A brick -red rhyolite porphyry , fine -grained . Non��oned oligoclue pheoncrys ts enclosed in a fine groundmaas of potaah feldspar , quartz , hematite and minor magnetite . Matrix is devitrified. c . Evidence for age "A K-Ar age determination haa estab lished that the rocks have a miniiiiWil age of 840 ± 30 m. y • • • • " (Aughenbaugh et al , 893) 4. Synonym& or closely re lated names See Littlewood dacite - 66 -

Loop Glaciation depos ita 1. Firat published use Nichola , R. L . MUltiple Glaciation in Wright Valley , McMUrdo Sound , Antarctica : Abstracts , Tenth Pacific Science Congress of Pac . Sci . Assoc . , p. 1 17 , 196 1 . 2 . Definition "The type depos it of the Loop Glaciation is approximately eight miles vest of the Lower Wright Glacier . It is a prominent looped , steep-a ided end moraine about 250 feet high Which is younger than the Pecten gravels . " (Nichola , 317) 3 . Type section a. Location 8 miles wes t of Lower Wright G lacier b. Lithology 1) ventifacts from WhiCh more than 1 ' of rock has been removed by sandblasting . 2 ) odd-shaped boulders from Which more than 3 ' has weathered off 3 ) pronounced yellow s tain c . Relat ion to other units Younger than Pecten Glaciation , but older than Trilogy Glaciation Lower Wrisbt Glacier till I 1 . Fira t published use R. L. NiChola ; MUltiple glaciation in the Wright Valley , MCMUrdo Sound , Antarctica ; GSA Spec Pap 68 ; p . 240 ; 1961 . 2 . Definition "A prominent end moraine approximately 8 miles wes t of the Lower Wright Glacier was depos ited during a s till younger glaciation. During the full-bodied stage of this glaciation the Lower Wright Glacier extended more than 9 miles farther up the Wright Valley than it does now. " (Nichola , 240) - 67 -