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

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b . Thickness At leas t 6600 feet . c . Lithology Widespread feldspathic pyroxenite , in layers 1 -3 m thick , and magnetite layers and lenses in sharp contact with thick anorthosite or leucogabbro layers . Cent imeter scale rhythmic layering . Many channel-like convect ion structures . Capped by 300 m of granophyre . d . Evidence for age "'!be age of the body is uncertain; but a pos t -Permian age is indicated by the metamorphic effects on nearby carbo­ naceous , Glossopteris -bearing sedimentary rocks . " (Schmidt , D . L . and Ford , A . B . Geology of the northern Pensacola Mountains and adjacent areas : Ant . Jour . u. s., vol . I , p . 125 , 1966 . ) Dust in Island granitoid rock 1 . Firs t published use Craddock , c., C . M. White, R. H. Rutford. The geology of the E ights Coas t : Ant . Jour . u. s. , 4 , p . 93-94 , 1969 . 2 . Definition "Dust in Island cons is ts of light gray granitoid rock containing numerous angular to rounded inclus ion of fine- to medium-crystalline mafic rock . " (Craddock et al , 93) 3 . Type section a . Locat ion Dus tin Is land , E ights Coas t E ast Base hornblende granite 1. Firs t published use Knowles , P. H. Geology of Southern Palmer Peninsula , Antarctica : Am. Phil . Soc. Proc . , 89 ( 1 ) , p . 136 -138 , 1945 . - 20 -

2 . Definit ion "The igneous rocks lie for the most part to the eas t of East Base and are compos ed of hornblende granite wh ich is somewhat variable in texture ; the mineral c�a ition , however , is uniform." (Knowles , 1945) 3 . Type sect ion a. Locat ion East Base , S tonington Island , Antarctic Peninsula b . Lithology Hornblende granite with coarse hypidiomorphic texture with a high percentage of orthoclase ; feldspars altered cons iderab ly . c . Re lation to other units 4. Remarks " in contact with a dark-colored hornblende gneiss wh ich exhibits cons iderable ch loritic alteration and contains small veinlets of secondary minerals . " Rocks in vic inity of base are dominant ly fe ls ic igneous variet ies wi th abundant metamorphic rocks adj acent to seacoas t . Con.tacts ir­ regular yet wel l-de fined in mos t places . Edsel Ford granodiorite 1. Firat published use • Warner , Lawrence A. Structure and Petrography of the Southern Edsel Ford Ranges Antarctica : Am. Phil. Soc . Proc . 89 , p . 78-122 , 1945 . 2 . Definition "The plutonic rocks include granodiorite and granite together with intermediate types o f monzonitic compos ition. Leuco representatives of all these types occur as late members of the igneous sequence . "'!be fact that hornblende and DllS covite are incompat ible in this region provides a bas is for dividing the rock into two facies . " (Warner, p . 87) - 2 1 -

3 . Type sect ion a. Location Raymond Fosdick and Rea Cooper Ranges of southe� Edsel Ford Range b . Lithology Plutonic rock , granodiorite to granite , with hornblende and muscovite varieties . c . Relation to other units. Intrude Edsel Ford metamorphic rocks ; the more basic plutonic types occur where the sedimentary s tructure is synclinal , whereas the leuco varieties have an affinity for anticlinal s tructures . Edsel Ford metamorphic rocks 1 . Firs t published use Passel , Charles F. Sedimentary Rocks of the Southern Edsel Ford Ranges , Marie Byrd Land , Antarctica : Am. Phil . Soc . Proc . 89 , P• 123 -131 , 1945 . 2 . Definit ion "All through the region the sediments are of a dark color and are uniformly fine-grained . • • • "The sediments cons ist of alternating beds of shale and sandstone which show effects of low-grade metamorphism. In the series the beds o ften reach a ·thickness of 10 feet; moat of the beds are · comparatively thin. The shale beds are usually finely laminated . " (Passel , 129-) 3 . Type section a. Location Garland Hershey Ridge , the Haines MDuDtains , and Mt . Donald �ward of the southern Edsel Ford Ranges. - 22 -

b. Thickness 15 , 000 feet estimated; 4600 feet minimam �ade, F. A. Geology of the Marie Byrd Land coastal sector of West Antarctica: Ant. Jour. U. s., vol. II , P• 93 -94 , 1967 . ) c. Lithology Quartzites and slates, grading into biotite schists and phyllites. d. Relation to other units Cut by Edsel Ford granodiorite e. Evidence for age No fossils; probably pre-Cretaceous Eights Coast quartz diorite 1. Firat published use Drake, A. A., Jr. Preliminary geologic report on the 196 1 u. s. expedition to Bellingshausen Sea, Antarctica: Science 135, P• 671·672 , 1962 . 2 . Definition "The principal rock exposed is quartz diorite. It is light gray to light medium gray, chalky White to buff-weathering, medium to medium-coarse-grained rock with very poor to good foliation." (Drake, 671 ) 3. Type section a. Location Eights Coast to 73°0418 , 90° 08 1 W, the easternmost point visited b. Lithology Medium- to coarse-grained, light gray to white quartz diorite. Dated sample had well-developed foliation of aligned biotite, hornblende and plagioclase; other specimens massive. Locally deformed as evidenced by·mortar structure, broken plagioclase and kinked biotite. - 23 -

c . Evidence for age E lbow Formation A spec imen from Peeler ' s Pinnacle on the E ights Coast yielded lead-alpha age from z ircon of 150 ± 20 m. y. but a K•Ar age from biotite of 97 ± 5 m. y . Drake , A . A. , Jr . ; T.W. Stern ; H. H . Thomas. Radiometric ages of z ircon and biotite in quartz diorite , E ights Coas t , Antarct ica : USGS Prof . Pap . 501-D , p . 50·53, 1964 . 1 . Firs t published use Schmidt , D. L . ; P. L. Williams ; W. H. Nelson; J, R. Ege. Upper Precambrian and Paleozoic s tratigraphy and s tructure of the Neptune Range , Antarct ica : USGS Prof Paper 525 -D , p . 112 -119 , 196 5 . 2 . Definit ion "The E lbow Formation is here named for E lbow Peak , where the type sect ion is des ignated along the east-wes t ridge along which the peak is s ituated . • • • The E lbow Format ion is a red-bed unit cons isting of interbedded red argillaceous s iltstone and gray fine -grained quartzose sands tone in well-indurated layers 1 to 4 feet thick ; the layers are made up of lamellae 1/16 to 1/4 inch thick. In overall color , about half the format ion is red and half is light gray . T:�e coarser grained layers are commonly mottled gray or gray with red specks . Cross -bedding is abundant and ripple -marked bedding planes are common." ( S chmidt and other, , 115 ) 3 . Type sect ion a. Locat ion Last west ridge upon wh ich Elbow Peak is s ituated, Neptune Range , Pensacola MOuntains , 83 ° 32 1 s, 56 °48 1 W b . Thickness 1 , 000 feet , thinning to south and west c . Lithology Light gray, fine-graine� cross -bedded quartzose sandstone and interbedded red argillaceous ripple -marked siltstone . - 24 -

d . Relation to other units Conformably overlies E lliott Sandstone . Gradat ionally overlain by Heiser Sandstone . e . Evidence for age "Younger than the Cambrian Nelson Limes tone of the second sequence , but from regional cons iderations it is probably not younger than Late Paleozoic . " (Schmidt and others , 115 ). See Neptune Group . E lliott Sands tone 1 . First published use Schmidt , D . L . , P . L . Williams , W . H . Nelson and J��- Ege . Upper Precambrian and Paleozoic stratigraphy and structure of the Neptune Range , Antarct ica : USGS Prof Paper 525-D , p . 112 -119, 1965 . 2 . Definit ion "The E lliott Sandstone is here named for E lliott Ridge , where it disconformably overl ies the Wiens Formation and is conformab ly overlain by the E lbow Format ion. • • • The Elliott cons ists of a pink to buff coarse -grained , crossbedded s ands tone with thick and thin interbedded conglomeratic beds and minor thin red shaly beds in the lower half. Volcanic detritus is common in the lower part , and quartz and roCk detritus are predominant in the upper part . Calcareous cement is characteris tic. " (Schmidt and others , ll5 ) 3. Type section a . Locat ion Eastern s lope of E lbow Peak , Neptune Range , Pensacola MOuntains , 83° 32 1 s, 56 °40 1 w. b . Thickness Averages about 2500 feet ; it is about 5000 feet thick on E lliot t Ridge but pinches out completely about 10 miles north of Elbow Peak. - 25 -

c . Lithology Pink to buff cross -bedded , coarse-grained sands tone , with thick and thin interbedded conglomerate beds and minor thin red shaly beds in lower half. d . Relat ion to other units Overlies Brown Ridge Conglomerate conformably Overlain by E lbow Format ion e . Evidence for age "Is younger than the Cambrian Nelson Limestone of the second sequence , but from regional cons iderat ions it is probably not younger than Late Paleozoic . " (Schmidt and other , 115 ) . See Neptune Group . E llsworth MOuntains sedimentary rocks 1 . Firs t published use Craddock , C . , J. J. Anderson, G . F. Webers . Geological out l ine of the E llsworth MOuntains : Polar Record Vol XI , no . 7 5 , p . 755-756 , 1963 . 2 . Definit ion "The muntains are composed of a thick sequence of deformed sedimentary rocks . The thickness o f the exposed s trat igraphic section exceeds 20 , 000 ft . ( 6100 m). Continuing work may reveal the presence of disconformities , but thus far no �nconformity has been es tablished in this section. MOst of the strata are clas t ic varieties , especially quartzite , conglomerate and pelite ; some of these contain material of volcanic derivat ion . A carbonate unit several thousand feet thick occurs near the base of the section. ( Craddock , 755-756 ) 3 . Type section a . Locat ion E llsworth MOuntains , between deformed belt of Antarct ic Peninsula and E as t Antarctic shield . b . Thickness 20 , 000 feet plus - 26 -

c . Lithology Quartz ite and marble (brecciated locally) Pelit ic rocks are argillite , s late and locally phyllite . MOst rocks possess poor to good secondary foliation. d . Evidence for age Worm borings , trilobites , gastropods , a probable cephalopod , plant s tems , etc . sugges t Paleozoic age . Youngest bedrock is no older than Ddddle Paleozoic . E ternity Range granodiorite 1 . First published use Knowles , P. H. Geology of Southern Palmer Peninsula, Antarct ica : Am. Phil . Soc . Proc . 89 ( 1) � p . 141-142 , 1945 . 2 . Definition "The Eternity Range , composed of granodiorite , represents the central core of the peninsula and proves beyond a doubt its igneous nature . " (Knowles , 1945 ) 3 . Type section a . Location Eternity Range , centrai Palmer Peninsula (now Antarctic Peninsula ) b . Lithology Biot ite granodiorite , mediWD-grained, hypidiomorphic texture , composed of a small amount of quartz , partially zoned plagioclase with calcic centers , orthoclase , high- iron biotite and some hornblende . 4 . Evidence for age Cretaceous or T ertiary? Executive Committee grey tuff 1. First published use Doumani , G . A. Geologic Observations fn West Antarctica during recent oversnow traverses : IGY Bull . 41 , Trans . Am. Geophys . Union 41(4) , p . 706 -710 , 1960 . - 27 -

2 . Definit ion See Execut ive Committee red tuff " cross -bedding , intercalat ion of strata , and part ial raunding of volcanic fragments characterizes the grey tuff , which thus resembles a river depos it . " (Doumni , 707 -708) 3 . Type section a . Locat ion Southeastern s lope of Executive Committee Range b . Thickness 50 meters c . Lithology Firm, coarse tuffaceous unit , dark grey to brown , graded bedding , cross -bedding and other sedimentary structure• . Bedding horizontal at base but changes to 30° d:f.p at top . Contains well -rounded , almost spheroidal basalt ic lapilli from 2-15 em in diameter . d . Relat ion to other units Overlies Execut ive Commdt tee yellow tuff OVerlain by MOunt S idley t ill 4. Remarks Occurs on Mt . S idley Execut ive Commit tee olivine andes ite 1. Firs t published use Doumani , G. A. Geologic Observations in Wes t Antarct ica during recent oversnow traverses : IGY Bull . 41 , Trans . Am. Geophya . Union 41(4) , p . 706 -7 10 , 1960 . 2 . Definition "The lowermos t unit is olivine basalt - a dark , extrus ive igneous rock rich in the iron-magnes ium s ilicate , olivine . At an elevation of about 2000 meters , the basalt surface displays sharp , symmetrical - 28 -

grooves , 10-15 cent imeters in depth , apparently the result of abras ion by rock fragments imbedded in s lowly flowing glacier ice ." (Doumani , 707 ) 3 . Type •ect ion a . Location Southeastern s lope o f the Execut ive Committee Range b . Lithology " • • • porphyritic olivine andes ite , containing large phenocrys ts of plagioclase and olivine embedded in a dark grey aphanit ic groundmass . The lower outcrops exhibit spectacular patterns of narrow, symmetrical grooves , 10-15 em deep and trending north ­ south . • • • Cons iderable amounts of this andes ite are reddish and highly ves icular , and contain euhedral plagioclase up to 6 em in length . 1 1 Doumani , G. A. Volcanoes of the Executive Commit tee Range : Antarct ic Geology , Proc . Capetown Sympos ium 1963 , John Wiley and Sons , p . 666 -675 , 1964 . c . Relation to other units Overlain by Execut ive Committee red tuff (probab ly unconformably ) d. Evidence for age 4 . Remarks "A middle Pliocene age ( 6 . 2 m. yr . ) is ass igned to the earlier stages of volcanic activity. " Doumni , G. A. Volcanoes of the Execut ive Committee Range , Marie B¥rd Land : Polar Record , Vol . XI, no . 75 , p . 787 , 1963 . Occurs on Mt . S idley Executive Committee red tuff 1 . First published use Douani , G . A. Geologic Obs ervations in Wes t Antarct ica during recent oversnov traverses : IGY Bull . 41 , Trans . Am. Geophys . Union 41(4) , p . 706 -710 , 1960 . - 29 -

2 . Definit ion "Overlying the basalt are three dis t inct rock units cons is ting of compacted , fine-grained volcanic fragments , or tuff . They are red , yellow, and gray , in ascending order , and the lowes t lies unconformably upon the basalt . • • These units are characterized by strong fragmentat ion and an abundance of accret ionary lapilli -volcanic pel lets , commonly with concentric s tructure . " (Doumani , 707 -708 ) 3 . Type sect ion a. Location Southeastern slope of Execut ive Committee Range b . Lithology Red tuff , hard we lded , coarse-grained with a gritty matrix high % of biotite , great amount of brecciat ion , angular 2 ·15 em fragments . c . Relat ion to other units Overl ies Execut ive Committee olivine basalt ( pos s ibly unconformably) Overlain by Execut ive Committee yellow tuff d. Evidence for age 4 . Remarks "A middle Pliocene age ( 6 . 2 m. y . ) is ass igned to the earlier s tages of volcanic activity. " Douani , G . A . Volcanoes o f the Execut ive Committee Range , Marie Byrd Land : Polar Record Vol . XI , no . 7 5 , p . 787 , 1963. Occurs on Mt . S idley Executive Committee yellow tuff 1. First published use Doumani , G . A . Geologic observations in West Antarctica during recent oversnow traverses : IGY Bull . 41 , Trans . Am. Geophys . Union 41(4) , p . 706 -710 , 1960 . - 30 -