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Reconnaissance of the Northwest Rim of the Colorado River Basin

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Reconnaissance of the Northwest Rim of the Colorado River Basin RME -77(Pt. ~ ) / Subject Category :' GEOLOGY 'AND MINERA,LOGY U NI TED STATES ATOMIC ENERGY COMM I SSION RECONN.AISS ...-lliCE OF THE NORTHWEST RIM OF THE COLORADO RIVER BASIN, WAYNE AND GARFIELD COUNTIES, UTAH By Robert C. Ge rhard January 1955 Exploration Division Grand J unct ion Operations Office Grand Junction, Colorado Tech n ic a l In formation Ser v i ce Oak. R i dge Te n nes s ee UNCLASSI FI ED I. REC (o NNA l qSA CE OF THE NORYrI1rJEST Rill OF' THE- COLORA OO RIVER BASIN, .. WAYNE AND GARFIELD COUN TIES, UTAH . .- ABSTRACT About five mont hs ' f:eld work was devoted to examining the Salt Wash and Mossback outcrops i n a 1,0 O-square--mile area along the north-" . west r"JTl of 'thE; Co oraclo River, Wayne and Garfield Counties, Utah.- In the Little Rockies district, oxidized d~posits of vanadium- . _ uranium ore, associated chiefl ; with ca r bonized wood, logs, and plant '. "~. fragments, occur in extremely small lenses in two horizons of the Salt ~~: Wash member of t he Morrison f ormation. Beca use of the small l~ri tic ular : .~. nature of presently known or ebodies, ?hysical ~xploration in t his dist r1c t ~ ~ does not now appear to be econOIll:..ca.J..J.Y f easible. 0 -' • __ - . .. "In the Sout he rn Green River Desert, urap.ium m:i.n era liz~tion a Ssc 'cia ted.} ~ ~'~:' ~ ~' with carbon trash, asphaltite, and copper mi nerals occurs in the lower " -~ .: Mossback channel unit fillino paleochannels cut into the Moenkopi for.mation ~ -:-" ... : -- -."- INTRODUC TION _::.... '~"; -:- Geologic reconP.ais sance was conducted to del i neate ground f~vorab l e '~ ~ .-:,= ~c-+ for exploratory drilling in r,he Salt \Aiash a nd Hossback s a nw.s tone~ . :'.'. '":".:..:' along the northwest r im of t he Color a do Ri ver, Wayne and Garf1~ld P ounties-;--_~ <" ·Ptah. As early as 19L5 t he Salt 1'1i ash depo'si ts of the Littl e Rockie; ·.. ~"~ .. ~ ~::"-' diSl.-rict were evalua ted by the TJnion Nines Development Corpo.ration til-· , - "--" ~ a detailed geologic report (1 ) . - . -, .' ." .. "- ~ ". From Feb ruary t o July~ 19S3, field r econnai s sance wa s conduc t e d -' '--'"'~'r in this ar ea. As t:.me and ef fort were equal_y divided betWeen the $alt. Wash .and :Hossback €Jr.-pcs e re, t he s:rr...aller Salt 1;Jash out~ rop belt wa s wo ....ked in greater det~. il. This r econnaissance consisted of traver sing the rim with a scintillat i on cOL:TIte r , meas ~rr:'ng CI'oss-stra ta to det eriiine s edi- . mentary t rends, taking str atigraphic se ~ t:onsfcr facies st~dy, examining mines and prospects to est ablish ore guices, and mappL~g ore trends to determine t heir size, €xte n t ~ a. d P CCI'_c!.".ic r-alue. Geologic r econnaissan:e 0: the Mos sback exposures was performed in · two phases. First, a m re detailed investigation, including mapping and · channel sampling 0: ~nes; making radioactivity surveysJ detarmining channel sand limits and sedimentary trends; and examining the rim for paleochannels, _ranium miner~ s, limonite, logs, carbon trash, and copper staining, was carried outo A regi onal recorxaissance made up the brief second phase. Prior to field study, an ai r su~vey was made to search for thick sands and . paleocha~~ els in the lower Mossback 5a~dstone of Millard Canyon and Elaterite Easin (figo 1). These outcrops were later investigated o~ the ground for anomalous radioactivity, uranium minerals, asphalt, copper stain, pyrite, logs and carbon trash. LOCATION AND ACCESSIBILITY The area covered by reconnai9s~~c e is a narrow strip about 15 miles wide and 65 miles long of the northwest rim of the Colorado . River Basin in Wayne and Garfield Counties, Utah (fig. 1). It covers approximately 1,000 square mi~es, lying between 110 andIll degrees west longitude. The area has not been su.bC.ivided by General Land Office survey. The Dirty Devil River divides the ·region into two physiographic - .. uni t.s. One, stretching northeast from the Dirty Devil to the Green· River (fig. lh is the Southern Green River Desert. The other pr~sio­ graphic unit lies southwest from the Dirty Devil River in the southern Henr,y Mountains basin, referred to as the Little Rockie! district. It extends southward f-om the southern boundary of T. 33 S., R. 12 Eo, Salt Lake Base ~~d Meridian, Utah, to Hansen Creek. The Little Rockies Basin is bounded by Mount Holmes and ~o un t E:.lsworth on the ea.st and Mount Hillars on the north (rig. 2). Access to botb the Southern Green River Desert and the Little Rockies district is by Utah State Hi ghwcS.y 24, a graded gravel road ex­ tending from Green River on Uo S. Highway 6-50 southwest to Hanksvilleo Localities in the Southern Green p~ er Desert are reached by traveling southeast from Temple crossroads ;~c·ion located on Utah Highway 24 for 50 miles over an unimpr6ved dirt a~d sand d~~e road to French Seep (fig. 3). Travel on this road r equire a four-wheel drive vehicleo Access to Mossback outcrops ir. Millard vanyon is gained by horseback down Outlaw Trail near French Seep. ~arts of Elaterite Basin may be reached by jeep on a new spur road branching east orf the trunk r oad which extends from French Seep to Hatch Canyon. Connecting jeep trails into Happy Canyon and South Fork, Hatch Canyon, were bu~ t fram t his trunk road. - 5 - EMER'r - - ~ WAYNE ~ -: \\ - SOUTHERN GREENRIVER DESERT' ... :::. - -. - , ...... : .. ::. .. ' .. - -, Figure I. Locat lQn of .the nor thwest rim, CO lorado ·River Wayne on<1 Garfield CountIes ,Utoh - 6 - . Jm ;',~ : ~ ' :- ,~ WOlt er Group R...--J WOOBRUFF SPRI :. : - 'qwoooru f ' Group J I t ~ . • •• I I · • • • • ~r "" OLMES 6 • • CROS S - STRATA MEASUREMENTS, , ~ ' o e l mont Group M1NERA ' IZEO OUT9WPS AT SHOOT A~ I NG AND WOODRUFF CL'AIM$ SWORT.H Gr o up '-J £ X P A NAT I ON ~----, ., Jm I Morr ison l __ -1 • • Unimproved rood Mine or prosp ec CROSS - STRATA ME' ASUREMENT'S. - C)roup LITT L E ROC KIES O !STR ICT S p r IO~ OCf 195" Figure 2 l_oca1 :on map one Salt Wash trends , Little Hockles district' Garf ield County, Utah .... ~ .-: - 1 - sou "'ERN GREE N '- Irlle for mo llo r: R IV E R DESER GRAND Unimproved rood TrOll X ~"o specl D CIOlm 9'O~P ~ Seep or SIH ln Q li e (!tICE ,.'s .GAOUP I [ \ \ \1 I: / I J Oct 19S4 F I ~ure 3 Lower Mossboc k facies and Channels, southern- .Gnutn River pesart - ~3 . · · . Po i sor: Spr :':lg= : ;: nyon ( ~ i g 0 1 ) i s r eached by cont1:nuing south on _" " Utah 24 from i e.mP e ~~ o s sroads t o P.anksvil lej thence south 12 miles on Utah 95 , a s econaarJT road, t o the Wayne-Garfield County line; thence east down Po i son Spri ngs (3ox Canyon ; for about L5 mileso From Poison Springs Canyon jeeps can ~ ea ch the mouth of Happy Canyon by fording the ­ Dirty Devil R~y er, but t ~av e~ sout h or north along the Dirty Devil is limited to foot t ~ai l s or horse t railso The Little Rockies dist r i ct is accessible to t wo - wheel drive veh:cles during fair weather by t r aveling sout h from Hanksville on Utah 95 to North Wash junction (fig. - .I , thence sout h 5 miles to Trachyte Creek on an unimproved r oad, t hence 15 miles over t he Hogback to Woodruff Spri ngs or Star Ranch Spring. The Delmont claims, Shootering Canyon, and Hans en Creek all may be reached on spurs branching from the trunk road ext endi ng , from Woodruff Springs. - In the Southern Gre en diver Desert, drinking wat er is obtainable at French Seep, flowing 1/2 gal lon per minute and at a seep in HapP7 Canyon flowing one gallon per minute . -T5. ter for drilling operations is not available from the- Dirty- -D evil Ri ver because of its deep, steep- . walled canyon. Water for drilling and domest ic use is available at Woodruff Springs , Star Ranch, and Indian Spri ng ( fig~ 2 i ..J..r. t he Little Rockies dist ricto Flow at Woodruff Springs is about 25 galloHs per minute. TOPOGRAPHY The Southern Green Ri ver Desert cO ~ 9 is ts of r elat ively flat-l ying sediments whose surface r i ses gently sout hward to approximat e ly . 7~OOO ' feet above sea level. This surface is m&~tled with shifting eolian sands and dissected--by numerous, deep, straight-sided canyonso These closely ' spaced finger-like canyons have resulted from prolonged headward erosion by tributaries of the Green and Di rty Devi l Riverso They are floored mainly by red beds of the Moenkopi forma t ion. Mossback sandst one i8- exposed in the lower parts of the se ~anyon walls and forms benches, ~ thinly-covered flats, and spur s ext e ~ding out into t he canyons. In ' Poison Springs Canyon, it weathers i nto a narrow dark brown bench known as the "Black Jump~" In places ~ his bench grades into large masses of weathered Mo!sback talus bl ockso Mount Hillars, Mount Holmes, and Mou.~t Ellsworth are the dominant topographic features of the Little Rockies distri~to They consist of igneous plugs and laccoliths partially covered with folded and faulted sediments.
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