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Home , Phosphoria Formation

Brigham Young University Geology Studies

Volume 27, Part 2

CONTENTS

The Kinnikinic Quartzite (Middle ) in the Type Area, Central , and a New Reference Section near Arco, Idaho ...... Robert Q. Oaks, Jr., and W. Calvin James

Geology of the Sage Valley 7 W' Quadrangle, Caribou County, Idaho, and Lincoln County, ...... J ohn L. Conner

Geology of the Elk Valley Quadrangle, Bear Lake and Caribou Counties, Idaho, and Lincoln County, Wyoming .... J. Floyd Hatch

Geology of the Woodruff Narrows Quadrangle, -Wyoming ...... Valen D. Ott

Geology and Ore Deposits of Mineral Mountain, Washington County, Utah ...... Stuart K. Morris

Conodonts and of the Lower in Western Utah and Eastern Nevada ...... Gary J. Newman

Relative Age Determination of Fault Scarps along the Southern Wasatch, Fish Springs, and House Ranges ...... Lee Piekarski

Geology and Mineral Deposits of the Lodi Hills, Nye County, Nevada ...... R. Blaine Rowley

The Flagstaff Formation: Depositional Environment and Paleoecology of Clastic Deposits near Salina, Utah ...... Steven W. Sperry

Geology of the Sewing Machine Pass Quadrangle, Central Wah Wah Range, Beaver County, Utah ...... Richard F. Wheeler

Publications and Maps of the Geology Department

Cover: Air photo of House Range fault scarp Courtesy of Lpe P~ekarski. A publicatioll of the Department of Geology Brigham Young Unrversiry

Provo, litah 84602

Editors

W. Ket~nethHamblin Cynthia hf. Gardner

Bllghdm Yomg linzwrfzrjv C;eolo~Stud~ei 17 published by rhe department. Geology Stud- 28 LonsIstS of graduate-student and staff rebearch In the department and occastonal paper\ from othe~contr~bucors Stadzesfor St~dmtssupplements the regular i~~esand IS lntetrded as a serles ut qhort papers of general Inrerest whlch ma? serve AS gu~desto the geolog of Utah for beginning students and laymen

ISSN 0068-1016 Distributed November 1980

l t -80600 46504 Geology of the Woodruff Narrows Quadrangle, Utah-Wyoming*

VALEND. OTT Marathon 011 Company Carper, Wyoming 82601

ABSTRACT.-T~~Woodruff Narrows Quadrangle lies in the heart of the Utah- amined the Bear River region between 1869 and 1878. They as- Idaho-Wyoming Overthrust Belt. The following formations crop out within sessed the general nature-and age of the rocks. Veatch (1907) the study area: Ordovician Fish Haven Dolomite (f236.4 m), Jeffer- son Formation (108 m) and Three Forks Formation (87 m), Mississippian reported on the deposits in northeastern Utah, Lodgepole (167 m) and Brazer Dolomite (397 m), - southeastern Idaho, and western Wyoming. However, he did Wells Formation (208 m), Permian Phosphoria Formation (259 m), little with the rocks below the Permian phosphate beds except Dinwoody Formation (174 m). Woodside (100-200 m), and to map them as undifferentiated Paleozoics. Richardson (1913) Thaynes Limestone (+30 m), Bear River Formation (+SO0 m), and Tertiary (f50 m) and Fowkes Formation (f50 m). Sttuc- subdivided the rocks of northern Utah into mappable turd geology is dom~natedby folding and thrusting of the mid-Mesozo~cSevier formations. Later (1941), he published a geologic map and re- orogeny. Major folds are generally asymmetric with west-dipping axial planes. port on the Randolph 30-minute quadrangle which includes The largest fold covers about 22 k2. Faultlng includes thrust faults, tear faults, the study area. and extensional faults. The Crawford Thrust puts Mississippian through Triass~c rocks on Cretaceous strata. The tear faults are all left-lateral. Until the present study was undertaken, Richardson's work Potential for economic accumulations of hydrocarbons is favorable within provided most of the geologic information for the Woodruff the study area. Potential for economic deposits of metals and nonmetals is Narrows Quadrangle. Regional studies by Armstrong and Oriel much less favorable (1965), Eardley (1967), and Royse, Warner, and Reese (1975) INTRODUCTION discussed the study area only in a general way. At present, Earl One of the best exposed Paleozoic and Mesozoic sections in Norris, a graduate student at Brigham Young University, is the Utah-Idaho-Wyoming Overthrust Belt is found in the conducting a biostratigraphic study of the Brazer Dolomite at Crawford Mountains of northeastern Utah where the stratigra- the type section to the north in Brazer Canyon. Randy Cham-

I~hic seauence I from Ordovician Fish Haven Dolomite to Trias- sic Thaynes Limestone is present. Some Cretaceous rocks and several Tertiary units are also exposed. Lower Cretaceous and older strata in the Woodruff Narrows Quadrangle were folded and faulted during the Sevier orogeny. Later extensional fault- ing has further complicated the geologic structure. Geologic mapping at a scale of 1:24,000 and interpretive cross-sections included in this report show the major geologic relationships. Stratigraphic sections have been measured; how- ever, no attempt has been made to detail the petrology or pa- leontology of each formation. Location The Woodruff Narrows 7%-minute quadrangle is located east of Woodruff in northeastern Utah (fig. 1). The Southern Crawford Mountains along the western side of the quadrangle extend southwards to the Bear River Valley. Woodruff Nar- rows are in a shallow canyon in the southeast corner of the map area where the Bear River changes course from north to west. Dirt roads and jeep trails provide excellent access during summer months to within 1.6 km of most points in the quad- rangle. Geologic Setting The Woodruff Narrows Quadrangle lies in the heart of the Utah-Idaho-Wyoming Overthrust Belt. This region is charac- terized by north-south mid-Mesozoic Sevier orogenic thrust faults with associated Sevier orogenic folds. In Paleozoic time the quadrangle was situated along the eastern edge of the Cor- dilleran geosyncline and in Cretaceous time along the western edge of the Rocky Mountain geosyncline. Prevlous Work I I , I Hayden, Peale, and Gannett of the Hayden Survey and LIGURE ,.-Index map shoving the location d the Woodruff Narrows Quad- King, Emmons, and Hague of the Fortieth Parallel Survey ex- rangIe

*A rhcsis prcwnrcd ro rhc Deprrrnenr of Geology, Brlgharn Ywng Unlvernry, tn prrd lulfillrnenr of rhe rcqutrcrncntr lor rhc dcgrm Marrcr of Scicncc, Dcccmbcr 1971. Thnlr chairrnm. Jsrncr L Bacr OTT berlain, also a graduate student at Brigham Young University, rocks generally are massive. is rare in 'the Fish Haven. is mapping the Rex Peak Quadrangle immediately north of the This characteristic, as well as color and texture, makes it readily study area. James L. Baer, professor of geology at Brigham distinguishable from younger dolomites in the study area. Young University, is currently mapping the Woodruff Quad- Several corals were collected from a horizon near the top of rangle immediately west and additional quadrangles to the the Fish Haven in the NE '/4 of section 11, T. 10 N, R. 7 E. north.--- - William T. Oliver of the U.S. Geological Survey identified Fieldwork was conducted in the spring and summer of them as follows: 1979. Mapping was done on aerial photographs (scale 1:24,000 and 1:36,000) and later transferred to the topographic base. Deiracorallium sp. Late Ordovician Stratigraphic sections were measured using a 100-foot tape and Catenipora sp. Ordovician- a Brunton compass. Lobocoralhm (?) Late Ordovician Grewingkia sp. (?) Late Ordovician Acknowledgments I gratefully acknowledge the guidance, counsel, and assist- These corals clearly mark the late Ordovician Bighorn-Red ance of my committee chairman, Dr. James L. Baer. He spent River fauna which is equivalent in age to the Fish Haven Dolo- many hours both in the field and back at the office reviewing mite-a change from Richardson's (1941) map. He called these my interpretations and editing my manuscript. Dr. Lehi outcrops Mississippian Brazer Dolomite thrust over Jefferson ~intze'sexpertise and timely comments are also greatly appre- Formation to the east. His "thrust" is actually an unconformity ciated. Special thanks are given to Marathon Oil Company, between the Fish Haven and Jefferson Dolomites. Chevron Oil Company, Gulf Energy and Minerals, and Amoco Richardson (1941) mapped exposures of Silurian Laketown Production Company for funding a regional study of which Dolomite to the north in the Rex Peak Quadrangle at the this investi~ation0 was a Dart. In addition. Marathon Oil Com- same stratigraphic position below the Jefferson Dolomite. Ber- pany provided valuable surface and subsurface data. My greatest dan and Duncan (1955) confirmed a late Ordovician age for appreciation goes to my dear wife Robyn for her help with typ- these rocks. Thus it appears that the light to medium gray ing and editorial corrections and for her patience with my dolomite beneath the Jefferson Formation, both in the study many extended absences from home. area and in the Rex Peak Quadrangle, is actually Ordovician Fish Haven Dolomite. STRATIGRAPHY Stratigraphy exposed in the Woodruff Narrows Quad- Devonian System rangle ranges from upper Ordovician carbonates to Tertiary Jefferjon Formation () volcanic tuffs (fig. 2). Paleozoic and lower Mesozoic The Jefferson Formation was named by Peale (1893) for ex- Crawford Mountains along rocks are restricted to the southern posures along the Missouri and Jefferson Rivers in the Three the western side of the study area (fig. 3). Upper Mesozoic and Forks Quadrangle, . The upper member, called the Tertiary rocks occur throughout the rest of the quadrangle but Birdbear Member in Montana and Wyoming and the Hyrum are mostly covered by Quaternary deposits. Earlier mapping by Dolomite in Utah, is a thick, cliff-forming dolomite. The lower Richardson (1941) was generally accurate. Nevertheless, several member. eauivalent to the Darbv Formation of western outcrops were misnamed because of facies changes, or not 1 Wyoming, is brownish gray, dark brown, or dark gray dolo- mapped altogether. mite. Only the lower member is present in the Woodruff Nar- rows Quadrangle. The upper member either was eroded off or Ordovician System was not deposited. Fish Haven Dolomite The Fish Haven Dolomite was named by Richardson The Jefferson in the study area is a dark brownish gray, (1913), from Fish Haven Creek, Bear Lake County, Idaho. In thin- to thick-bedded or massive, sugary dolomite about 108 m thick. A few thin reddish limestone units may be interbedded the map area this formation is exposed in sections 11 and 14, T. 10 N, R. 7 E (fig. 3), where it is unconformably overlain by with the dolomite (see appendix). It is considered to be Late the Jefferson Formation and consists of massive to thick-bedded Devonian despite the fact that fossils well enough preserved for crystalline, light to medium gray dolomite. It is remarkably dating are rare. In the study area the Jefferson Formation, with- uniform in color and texture throughout but occasionally may out exception, weathers to a dark brownish gray ledge or cliff. be thin bedded or have thin, white discontinuous limestone It is easily distinguished from the lighter Fish Haven Dolomite lenses. Locally it may show white and gray mottling. below, and the reddish Three Forks Formation above. Like the Overall the Fish Haven Dolomite is a dense crystalline rock Fish Haven, the Jefferson has very little chert. with low porosity and permeability. Secondary porosity may be excellent near fault contacts where the brittle rock has been Three Forks Formation highly fractured (fig. 4). Along the thrust fault in section 11 The Three Forks Formation was named by Peale (1893) for the Fish Haven is so intensely brecciated that some of the bed- exposures near Three Forks, Montana. The type section was es- ding is indistinguishable. A section was measured westward tablished by Sloss and Laird (1947) at Logan, Montana. Where from this fault to the top of the Fish Haven (see appendix). it crops out in the study area, the Three Forks is a poorly ex- Total thickness for the sequence is 236.4 m. posed, nonresistant, reddish weathering unit (see appendix). Because of its resistant nature the Fish Haven Dolomite Reddish, calcareous shale interbedded throughout gives the en- forms well-exposed ledges and cliffs. The formation viewed tire sequence a bright reddish color. Thus, a marked contrast from a distance appears as a homogeneous, massive, light-gray- exists between the Three Forks above and the Jefferson Forma- weathering rock beneath the darker units above. Closer in- tion below. The Three Forks in the study area is only about spection reveals that bedding is fairly common even though the 87 m thick. GEOLOGY OF THE WOODRUFF NARROWS QUADRANGLE, UTAH-WYOMING

Oulwosh, terraces, grovels. Tuffocrous mudstone ond sondslone , coorse conglomerole.

Voriegohd mudslone, sondslanr, conglomeroh and limeslone. Sillstone, cloyslone, sondslone 8 porcelonile.

Thin-bedded shole inlerbedded with fine lo coorse sondslone ond fossiliferous limestone.

Bosol conglomerate gradw upward through colcoreaus lo quorlzihc sondslone, lo mudslone ond sillslone.

Fine-grained sondslone ond limes?one. Thin-bedded, fine-groinrd sondslone ,sondy silfstone, silly cloyslone.

Penfocrinus - beolg limestone ond colcoreous sillslone.

Buff lo pinkish /on regulor bedded, portly cross- bedded ond mossive, fine-lo medium- groined well-sorled qlze. 8 slighlly colc ss. Colored colc. mudslone, fine-groinrd qlze. 6 1 colcoreous sondslone ond sillslone.

Sil/y cloyslone ond s17fy limeslone.

Lominoted lo medium-bedded siltstone. lnlerbedded sillslones ond sandy limeslones. Lominoled to lhin-bedded shole, dusk blue deft in mosl of lop l/3. Fine-groined lo coorse r -bedded mossive ss. Thinlo medium-bedded light gray dolomile , cherl slringers and nodules. Thin-bedded, fossiliferous limeslone. lnlerbedded limeslones, sholes 8 sondslones. Medium-bedded dork brown dolomile. UNCONFORMI TY Thin- lo thick - bedded dolomile.

FIGURE2.-General stratigraphic column for the Crawford Mountain area. Paleozoic and Tertiary thicknesses in meters from measured sections (see appendix). Mesozoic thicknesses in meters from Ruby, Oriel, and Tracy (1975). 70 V. D. OTT

Mississippian System mation and is in turn overlain by the Brazer Dolomite. The Lod~epole- - Limestone Lodgepole consists of 167 m of mostly thin-bedded, blocky, me- The Lower Mississippian Lodgepole Limestone of the Madi- dium gray . The lower 91 m contain occasional si- son Group was named by Collier and Cathcart (1922) from ex- liceous carbonate nodules which weather moderate brown (see posures in Lodgepole Canyon, Little Rocky Mountain region, appendix). The formation is fairly resistant and forms ledges Montana. A type section was designated at the same location where exposed. It usually weathers into medium gray blocky by Sloss and Hamblin (1942). talus covering the underlying nonresistant Three Forks Forma- In the northwest corner of the Woodruff Narrows Quad- tion. Fossils are abundant in the Lodgepole and include the rangle, the Lodgepole Limestone overlies the Three Forks For- following genera:

FIGURE4.-Stronglv fractured Fish Haven Dolomite.

72 V. D. OTT stones range from coarsely crystalline units to sandy coquinas Cretaceous rocks in the Woodruff Narrows Quadrangle of broken and pelecypod shells. Small pectins can have all been mapped as undivided Bear River Formation for be found locally, but recrystallization has generally destroyed all several reasons. No complete section of Bear River is exposed but the largest morphologic features. No complete section of anywhere in the map area. Structure and Quaternary cover fur- Thaynes crops out in the study area, but approximately 30 m ther compound the problem of assigning each outcrop to a spe- are exposed. cific unit in the Cretaceous section. Most outcrops fit the de- scription of more than one of Rubey's informal Bear River Cretaceous System units. With the data available it was not feasible to sub- Bear River Fornation divide the Bear River Formation in the Woodruff Narrows The Lower Cretaceous Bear River Formation was named by Quadrangle. Hayden (1869) for exposures near Bear River City, Wyoming. Bear River Formation in the Woodruff Narrows area is Rubey is credited by Moritz (1953) with subdividing the for- dark gray shale with interbedded thin, resistant and mation into informal units A through E. His descriptions are limestone coquinas that weather brown. Gastropods and bi- worth repeating here: (A) thin sequence of black and valves are abundant in the limestone. North of the Lower Nar- tan quartzitic ; (B) series of essentially non- rows the Bear River is unconformably overlain by the Wasatch fossiliferous red and variegated mudstones and sandstones; (C) Formation. In the hills just south of Session Pass and at the series of light colored gray and tan sandstones, limestones, and Narrows Reservoir, the dark gray shales are underlain by a shales, with numerous coal beds; (D) a second series of red and sandstone-redbed sequence. This distinct change in lithology variegated mudstones and sandstdnei; and (E) gray shales, tan has been mapped at Session Pass to show offset on several nor- sandstones. and numerous vorcellanite beds (like those of the mal faults in the area. North of Session Pass, along what Aspen shale) throughout. '1n its lower par; unit E contains Veatch (1907) called the Narrows Anticline, the same sand- coal beds; its upper part contains red mudstones and con- stone-redbed sequence continues to the northern quadrangle glomerates. Later, Rubey (1973) formalized these units into the boundary. Sandstone outcrops at Mud Spring, in section 18, T. Smiths, Bear River, Thomas Fork, Cokwille, and Sage Junction 10 N, R. 8 E, also belong to the Bear River Formation. Similar Formations. outcrops also appear in sections 17, 19, and 20 to the southeast.

FIGURE 5.-C~ctaceoussandstones and conglomcratcs near Mud Spring. GEOLOGY OF THE WOODRUFF NARROWS QUADRANGLE. UTAH-WYOMING 73

All consist of coarse, gray, poorly sorted sandstone and con- glomerates are algal limestone balls (fig. 7). The Wasatch in glomerate (fig. 5). Rocks of about the same lithology crop out this area is less than 60 m thick. along the northern quadrangle boundary just east of the Craw- ford Thrust. Several other exposures too small to map at a scale Fodes Formation of 1:24,000 also occur along the edge of Warner Hollow to the The Fowkes Formation was named at Fowkes Ranch near east. Evanston, Wyoming, by Veatch (1907). In the Woodruff Nar- rows Quadrangle it covers large areas from Session Pass to An angular unconformity between tan Bear River sand- Warner Spring and southwest of the Lower Woodruff Nar- stones below and the Wasatch Formation above (fig. 6) is ex- rows. Where exposed the Fowkes Formation consists of inter- posed along the north side of Warner Hollow. The Bear River bedded gray green tuffs, sandstones, siltstones, and shales rich dips west and the Wasatch dips east. More than 317 m of Cre- in magnetite and biotite. Locally it may contain pink and red taceous were measured at this location (see appendix). In addi- tuffaceous siltstones and shales. The formation is nonresistant tion, a small patch of Cretaceous rocks is exposed east of the to erosion, is seldom well exposed, and weathers into low, Crawford Thrust near the southern tip of the Crawford Moun- rounded hills. tains. This exposure also consists of poorly sorted sandstone and conglomerate. Some of the larger clasts can be identified as Quaternary Deposits Wells, Brazer, or Phosphoria rocks. Quaternary deposits in the Woodruff Narrows Quadrangle are four basic types as follows: (1) pediment gravels covering Eocene Series most of Dry Hollow, (2) alluvium and valley fill along Cotton- Wasatch Formation wood Creek and the Bear River Valley, (3) colluvium com- The Wasatch Formation was named by Hayden (1869) for posed of talus and alluvial fan debris, and (4) Recent sand outcrops in Echo Canyon near Echo, Utah. In the Woodruff dunes along the west side of the Crawford Mountains. The h arrows Quadrangle the Wasatch, with two minor exceptions, pediment gravels consist mostly of boulders, cobbles, pebbles, unconformably overlies the Bear River Formation. The friable and sand derived from Paleozoic rocks in the area. Alluvium reddish sandstone, siltstone, and conglomerate above the dark and valley fill are primarily sand, silt, and clay. Colluvium is gray shales in sections 17 and 20, north of the Lower Narrows, generally angular to subrounded cobbles and boulders found at belong to the Wasatch Formation. The only other exposures of the base of many cliffs or in several alluvial fans. The Recent Wasatch in the map area are near Warner Springs at the north- sand dunes along the west side of the Crawford Mountains em quadrangle boundary and immediately west along the consist mostly of pinkish medium-grained, subrounded, quartz Crawford Thrust. These exposures are quite different lithologi- sand. It probably is derived from reddish Wasatch Formation cally from the Wasatch Formation in sections 17 and 20. They outcrops to the west. are mainly white, red, or brown algal limestone interbedded with variegated calcareous sandy or silty units. The outcrops STRUCTURAL GEOLOGY have the appearance of coarse conglomerate interbedded with Structural geology in the Woodruff Narrows Quadrangle nonresistant slope formers. Closer inspection reveals the con- is strongly dominated by folding and thrusting of the mid-

FIGURE6.-White line shows the position of the angular unconformity between the Bear River Formation below and the Wasatch Formation above. 74 V. D. OTT

Mesozoic Sevier orogeny. Five steep anticlines and synclines are is overturned by as much as 30'. This combination produced clearly expressed. Thrusts place Paleozoic strata on younger Pa- an axial plane inclined to the west. The structure k doubly leozoic or Mesozoic strata. Later extensional faulting has cut plunging north and south from a point in the east central part earlier geologic structure. Six unconformities add further of section 35, T. 10 N, R. 7 E. The southward plunge steepens complexity. near the southern tip of the anticline where it is buried by allu- vium of the Bear River Vallev. Northwest of the Southern Folds Crawford Anticline is a smaller open syncline plunging to the Sevier folding and thrusting began in the region during southwest. This structure is a gentle symmetric fold much less late time (Armstrong and Oriel 1965). The re- complicated than the Wood Pass Syncline. sulting deformation produced the Wood Pass Syncline (fig. 3), The Narrows Anticline, named by Veatch (1907), is situat- the Southern Crawford Anticline, the Narrows Anticline, and ed along the eastern quadrangle boundary in the vicinity of Ses- numerous smaller folds. The Wood Pass Syncline is an asym- sion Pass. The fold is divided by faulting at this pass. The metric closed fold (see cross-section A-A') plunging southwest. northern part plunges northeast and the southern part plunges The western limb is generally more steeply inclined than the southwest. The fold is fairly simple with no overturning found eastern limb except in the northwest quarter of section 12, T. in the map area. The graben at Session Pass shows the axial 10 N, R. 7 E, where minor folding flattens it somewhat. In the plane to be nearly vertical or inclined slightly westward. The southwest quarter of the same section the syncline has been Narrows Anticline is complemented by a syncline to the south- bent eastwaid so that it now plunges to the southeast. In sec- east with its axis located along the Woodruff Lower Narrows. tion 13, T. 10 N, R. 7 E, the western limb is partly truncated This structure is a broad, gentle fold plunging northeast off the by a thrust. The fold finally ends near the center of section 13, map area. where it is cut by an east-west striking tear fault. Beds de- formed by the syncline include Mississippian Brazer Dolomite Faults through Triassic Thaynes Limestone. Faults in the study area can be categorized as thrust faults, The Southern Crawford Anticline is an asymmetric over- tear faults, and extensional faults. Most of the thrusts increase turned fold several kilometers long, oriented roughly north- in dip upward and may surface at a high inclination. Tear south along the west central quadrangle boundary. The west- faults are associated with thrusting, and both are the same age ern limb has gentle dips of less than 25O, and the eastern limb as the Sevier orogenic folding in the area.

FIGURE7.-Wasatch Formation consisting almoct entirely of algal limestone hall?. GEOLOGY OF THE WOODRUFF NARROWS QUADRANGLE, UTAH-WYOMING 75 ThwFaults beddlng. In the Wood Pass area repeated movement on the The Crawford Thrust was first mapped by Richardson tear fault system has offset the Leefe Fault to the west. To the (1941) along the east side of the Crawford Mountains. Th~s south the fault d~esout at the southern tip of the Crawford study indicates Richardson was correct in placing the Crawford Mountains. Thrust where he did. However, ~t 1s not a single thrust as he The eastern system extends north from the Woodruff Nar- mapped it but is actually a compound fault. In section 24, T. rows Reservoir to beyond the quadrangle boundary. It is com- 10 N, R. 7 E, it branches. To the northeast Mississippian Bra- posed of a series of short normal faults of varylng displacement zer Dolomlte has been thrust over Cretaceous Bear Rlver For- almost approaching an en echelon pattern. The pattern, how- mation. This is the fault Richardson mapped. A second branch ever, is broken by a northwest strlking graben at Session Pass. continues northwest from section 24, ;hen west, and finally On the cross-sections accompanying this report (fig. 3) most of north along the western limb of the Wood Pass Syncline. The the normal faults have been shown as listr~cin nature It is pre- variat~onin str~keof this branch is caused by Interaction with sumed that they flatten and join a pre-exist~ngthrust system at the tear fault system at Wood Pass. This Interaction will be ex- depth. ~lainedin detail in a later section. The thrust outs Mis- sissippian rocks in contact with Pennsylvanian, Permian, and Proposed Model Tr~assic rocks along this limb of the Wood Pass Syncline A proposed structural model for the Woodruff Narrows Where the strike of this thrust changes from west to north In Quadrangle is shown in figure 8. The model is modified from the southeast quarter of section 11, ~t is paralleled on the west an interpretation of the Darby-Hogsback-Prospect thrust sys- by a thrust of large stratigraphic d~splacement.This western tem by Royse, Warner, and Reese (1975). Two wells In prog- thrust puts Ordovician Fish Haven Dolomite against Mis- ress w~thinthe quadrangle (Marathon, Mud Springs 1-8; Chev- sissippian Brazer and Pennsylvanian-Permian Wells. The two ron-Getty, Narrows South 29-15) have supplled some well faults join together north of the map area and become one control. Additional informat~onwas obtained from seismic in- thrust. teroretations bv Marathon Oil Comoanv.I i However. some of Two small thrusts have also been mapped In the study area the subsurface features in figure 8 are inferred. Nevertheless, The first 1s southwest of Wood Pass in the northeast quarter of the diagrams are not casually drawn; considerable surface evl- section 14. This short fault strikes north and offsets two left- dence exists to support them lateral tear faults In a steplike manner. The thrust puts Devon- Diagram A shows the footwall block just after movement ian Three Forks Formation over Mississippian Brazer Dolom~te. on the Crawford Thrust. The overlying hanglng wall has been The second thrust is along the eastern limb of the overturned removed to show the general geometric shape of the fault Southern Crawford Anticline. The fault occurs along the Bra- plane. D~agramsB and C show the shape of the fault plane af- zer-Wells contact in sections 1 and 12, T. 9 N, R 7 E, and ter movement on two successively younger thrusts. These section 36, T. 10 N, R. 7 E; as a result part of the Wells is cut thrusts did not extend as far south as the older Crawford out. Several intermittent streams show disrupted drainages Thrust. Consequently, two transverse footwall "steps" were where thev cross the fault lane. Initial movement on this formed in the footwall block. The present surface geology 1s thrust probably occurred during formation of the Southern shown In Diagram D. The hanglng-wall block has now been Crawford Anticllne. added to show the surface expression when three success~vely younger thrusts llnk up. The transverse footwall "steps" have a Tear Faults profound effect upon the original thrust sheet riding "piggy- High-angle tear faults occur in the structurally complex back" on younger thrusts Because of stacking, a tear occurs In area near Wood Pass This left-lateral system consists of several the overlying sheets producing extens~onal and strike-slip short strike-sl~pfaults which begin and end at a thrust contact faults. This effect IS well displayed near Wood Pass. The com- In a steplike manner. Apparent offset on individual faults sug- plex structure in the Wood Pass area is easily explained by gests displacements of more than 0.8 km to 1.6 km Total dls- three thrust sheets stacked one on tooI of each other. If the placement on the complete system, however, is difficult to de- model shown in figure 8 is accurate, the westernmost thrust termine Considerable d~p-slipmovement may have occurred fault is part of the orlginal Crawford Thrust. making net sl~pimpossible to calculate without some pre- The fault now mapped as the Crawford Thrust is a younger faulting markers. A northern continuation of the strata found feature and belongs to the second sheet In the stack. A third in the Southern Crawford Anticllne has not been located to the fault-the youngest-is some distance to the east. Seismic data west. This fact suggests a minimum left-lateral displacement for from Marathon Oil Company gives evidence for a thrust be- the system of at least 4.8 km. These faults strike roughly east- neath Cottonwood Creek in Dry Hollow and some related de- west with the exception of a northeast striklng fault in section formation Immediately west. Th~sfault is shown in figure 8 as 13, T. 10 N, R. 7 E. the Dry Hollow Thrust. The deformation may have resulted from ramping in the fault plane. The tear seen at Wood Pass Extensional Faults could well extend this far east beneath the overlying pediment High-angle extens~onal faulting began in this region as gravels The overturned Southern Crawford Anticline can be early as Eocene time and has continued to the Recent (Arm- explained by the model as the upper sheet in a two-sheet stack. strong and Oriel 1965). Two persistent north-south normal The origlnal Crawford Thrust has been wrinkled as lt was car- fault systems roughly parallel each other on the western and r~ed"piggyback" by the younger fault now mapped as the eastern sides of the map area. The western system can be traced Crawford Thrust. The southern tip of the anticllne plunges northward at least as far as Leefe. No name has been given to steeolvI I south and is truncated bv Inferred extens~onal and lt; therefore ~t 1s proposed that this fault system be called the strike-slip faults associated with a transverse step in the sub- Leefe Fault It has downdropped the Bear River Valley on the surface. The Leefe Fault also may end there if ~t is in fact a west a minimum of 425 m and probably much more In the listric fault. The Bear River changes course east-west in a pecu- study area it generally cuts Paleozoic rocks at a high angle to liar manner between Woodruff Narrows Reservoir and Wood- A. Early Crawford fault plane.

- D. Generalized geology I Purl inferred / at present. B. Compound Crawford - Crawford branch - fault plane.

FIGURE8.-Proposed model showing the structural evolution of the study area (see text for explanation). In order to show steps In the footwall, the north onenta tlon does not follow the usual convention. GEOLOGY OF THE WOODRUFF NARROWS QUADRANGLE, UTAH-WYOMING 77 ruff, Utah. The river may well be down-cutting through bed- time with only occasional gentle upllft and subsidence. From rock made less resistant by prior tear faulting along both then until the Recent, tectonic activity has dominated the ma- branches of the Crawford Thrust. Seismic data suggests the jor geologic events in the Woodruff Narrows Quadrangle. Crawford Thrust at the Bear Rlver is offset eastward about 2.4 km (2 mi). , I In summary, the evolution of structural elements in the Ordovician and Devonian strata in the study area were de- Woodruff Narrows Quadrangle can best be explained by a pro- posted in a shallow marlne environment along the eastern Cor- posed model shown in figure 8. The model explains many sur- dilleran miogeoclinal shelf (Stewart and Poole 1974). The Silu- face features as follows: (1) the obvious difference in age be- rian strata have all been removed by erosion but were probably tween the thrust faults near Wood Pass, (2) the presence of deposited in the same environment. Miss~ssippian sedimenta- tear faults in the same area, (3) the difference in elevation be- tion along the eastern Cordilleran mlogeoclinal belt was domi- tween the Crawford ~ountainsnorthand south, (4) structural nated by the Madlson-Brazer basln (Bissell 1974). The Lodge- deformation of Cretaceous beds near Warner and Mud Springs, pole Limestone and Brazer Dolomite now found in the study (5) the position of Cottonwood Creek, (6) the overturned area were deposited in shallow marine waters along the eastern Southern Crawford Anticline, (7) the sudden southward edge of this basln. Later erosion removed any Late Mis- plunge near the Bear River of the Southern Crawford Anti- sissippian and Early Pennsylvanian strata deposited. The Madi- cline, (8) an end to the surface expression of the Leefe Fault, son-Brazer Basin was the forerunner of the Oquirrh and Sub- and (9) peculiar east-west change in course of the Bear R~ver lette Basins of Pennsylvanian and Permian tlmes. The Wells In addition, interpretation of seismic data indicates a thrust In and Phosphorla Format~onswere deposited on an eastern shelf Dry Hollow and east-west offset on the Crawford Thrust. of these two depocenters. Latest Permian and earliest Triassic Structural events from oldest to youngest include the follow- time is represented by an unconformity above the Phosphoria ing: (1) movement on the early Crawford fault plane, (2) Formation. By early Tr~assictime these basins were more or less movement on the present Crawford fault plane with devel- joined and somewhat smaller Sediment laid down in this later opment of a transverse step and tear faultlng in the alloch- depocenter became the Thaynes and other formations found in thonous block, (3) movement on the Dry Hollow fault plane the map area. with development of another transverse step at Wood Pass and tear faultlng in two sheets riding piggyback on the alloch- Tectonics thonous block, and (4) Eocene to Recent extensional faulting. The was a time of great change for the Cordil- leran region. Armstrong (1968), in discussing the Cordilleran, UNCONFORMITIES feels that about mid-Triassic tlme uplift was initiated in the The unconformltles present in the Woodruff Narrows area, and the marine seas began to withdraw. By Middle Juras- Quadrangle are between the following unlts (1) Fish Haven SIC the reglon was undergoing orogenic deformation and sup- Dolomite-Jefferson Formation, (2) Three Forks Formation- plying sediment to the newly formed Rocky Mountain geosyn- Lodgepole Limestone; (3) Brazer Dolomite-Wells Formation, cllne to the east. This marked the end for a time of marine (4) Phosphoria Formation-Dinwoody Formation, (5) Bear Riv- deposition in the Woodruff Narrows Quadrangle that had er Formation-Wasatch Formation, and (6) Fowkes Forma- been going on almost continuously since the late . tion-pedlment gravels. The first four unconformities all have The orogenic activ~tywhich took place in the former Cor- the same characteristics. None of them show an angu- dilleran region eventually culm~natedin the Swier orogeny. lar discordance between the beds above and the beds below. Sediments deposited there during the late Triassic, , and They are all disconformable relationsh~ps.The erosional vacuity Cretaceous consist of both marine and cont~nental strata. represented by each is difficult to determine. However, all the Rocks In the map area as young as the Lower Cretaceous Bear Sllurian is missing between the Fish Haven and Jefferson Dolo- River Formation were lnvolved in the Sevier orogenic folding mites. Apparently there was only gentle uplift and subsidence and thrusting. Figure 9 shows the general~zedevolution of the during development of any one indiv~dualunconformity. No study area during and after the Sevier orogeny. Extensional paleosols, lag sands, conglomerates, or buried eros~onalsurfaces faulting in the Utah-Idaho-Wyoming thrust belt began as early with substantial relief were found associated with any of the as Eocene time and has continued until the Recent (Armstrong disconformities and Oriel 1965). The unconformity between the Bear River and Wasatch Formations shows a good angular discordance at Warner ECONOMIC POTENTIAL Spnng. The Bear River below dips 19' to 24' west; the The economic potential for hydrocarbons within the Wasatch above is nearly horizontal. The resistant sandstones in Woodruff Narrows Quadrangle is good. On the other hand, the tilted Bear River Formation formed paleoridges during the the potential for metals and nonmetals is meager at present. erosional period after Swier orogenic thrusting and before the Wasatch Formation was deposited. Near Warner Spring these Hydrocarbons paleoridges can be clearly seen with Wasatch Formation filling The Crawford Thrust has been the focus of Intense hydro- the intervening paleovalleys. The unconformity between the carbon exploration in the last few years. Several promising Fowkes Formation and the overlying pediment gravels may not structures In the area have been tested. American Quasar's be fully developed The gravels are not yet lithified and may be Hogsback well to the northwest is presently producing gas removed in the future allowing future erosion of the Fowkes from the Dinwoody Formation. At present (September 1979) Marathon Oil Company has a wlldcat test underway in section GEOLOGIC HlSTORY 8, T. 10 N, R. 8 E (Mud Sprlngs 1-8), and Getty Oil Company The earliest recorded geologic events in the study area be- has one underway in section 29, T. 19 N, R. 120 M (Narrows gan wlth Ordovician sedimentation along the Cordilleran shelf. South 1-29). Favorable structures may also exist in the autoch- It continued throughout the Paleozoic Era and into Mesozoic thon beneath the Crawford Thrust The strata in the area con- tain abundant source and reservoir rocks. Source beds include Forks Formation, Lodgepole Limestone, Brazer Dolomite, the Lodgepole Limestone, Phosphoria Formation, Thaynes Wells Formation, and Phosphoria Formation are exposed with- Limestone, Twin Creek Limestone, and Bear River Formation. in the Woodruff Narrows 7M-minute quadrangle. In addition, Possible reservoir rocks are the Wells Formation, Phosphoria the Mesozoic and Cenozoic deposits found there include the Formation, Dinwoody Formation, Thaynes Limestone, Wood- following: Dinwoody Formation, Woodside Shale, Thaynes side Shale, Nugget Sandstone, Twin Creek Limestone, Stump Limestone, Bear River Formation, Wasatch Formation, Fowkes Sandstone, and Bear River Formation. It is hoped that future Formation, pediment gravels, colluvium, alluvium, and Recent exploration in the map area will discover commercial quantities sand dunes. All the major geologic time periods since the Cam- of oil and gas. brian have at least one time stratigraphic unit exposed in the study area, except the Silurian and the Jurassic. The Silurian Metals strata were eroded away during Paleozoic uplift. The Jurassic Igneous rock in the study area is restricted entirely to the rocks probably exist at depth beneath overlying Cretaceous volcanic tuffs of the Fowkes Formation. The chance of finding units. an economic metallic deposit associated with igneous rocks is The structure found in the study area is dominated by Se- quite small. Similarly, no metallic sedimentary occurrences have vier folding, thrusting, and strike-slip tear faulting. Later yet been found in the quadrangle. Eocene to Recent extensional faults add further complexity to the structure. Major events leading to development of the pres- Nonmetals ent geology found in the map area began with the Cordilleran Gravel and phosphate are the only two nonmetals that miogeocline and its associated basins. Later, evolution of the have been quarried or mined in the map area. However, their Rocky Mountain geosyncline affected the area during early and economic contribution has been limited. Several quarries in the middle Mesozoic times. Intense structural deformation fol- area have supplied gravel, mainly as local road material. Gravel lowed in Cretaceous time with the Sevier orogeny. Eocene to is plentiful and therefore does not command a respectable price. Recent extensional faulting has been the last major event re- Phosphate has been widely prospected in the Phosphoria For- corded. Economic potential for hydrocarbons in the study area mation. Nevertheless, only a few tons at most have been pro- shows some promise. The potential for metals and nonmetals is duced within the quadrangle. The Phosphoria in the study area meager. is thin and the phosphate poor. It is unlikely that in the future A pollen analysis of the Cretaceous strata within the any large deposits will be found. Woodruff Narrows Quadrangle would probably accomplish two things. First, it would determine more accurately the age CONCLUSION AND RECOMMENDATlONS FOR FUTURE STUDIES of thrusting on the Crawford Thrust. Secondly, it would help One of the best exposed Paleozoic sections in the Over- determine the relative position of each outcrop in the Cre- thrust Belt is found in the Crawford Mountains of north- taceous section. A paleoecology-petrology study could be done eastern Utah. Fish Haven Dolomite, Jefferson Dolomite, Three on the Rex Chert to determine why it changes facies from the

1 Lote Eorly- Crelaceous 3 Lole Eocene

K -

J I M-P C- D

FIGURE9.-Generalized diagram show~ngmajor episodes In development of the study area since early Cretaceous times. (1) nearly hortzontal beds, (2) Srvie~ thrusting, (3) Eocene sedimentation, (4) extensional faulting GEOLOGY OF THE WOODRUFF NARROWS QUADRANGLE, UTAH-WYOMING 79 typical dark gray chert to cross-bedded sandstone. This sort of Unrf study might help to increase our understanding of late Paleo- Unrt Thlcknes~ No. (meters) zoic sedimentation and tectonics in the area. 12 5 0 Sandstone, med~umgralned, pale yellow~sh brown, weathers pale yellow~sh brown, lam- APPENDIX nated to thln bedded, ledge, subrounded gralns, Measured Strat~graph~cSecoons sortlng poor, calcareous, duty Covered slope Sectron I Sandstone as above A mlne cut near the center of sectlon 5, T 11 N, R 8 E, In the Rex Peake Covered slope Quadrangle exposes the base of the Eocene Fowkes Formarlon resrlng uncon- formably on the PermIan Phosphona A sectlon was measured from the base of Sandstone, med~umgralned, dark yellow~shor- the formation eastward along a dlrt road to the eroded top of the formarlon ange, weathers moderate yellow~shbrown, very thln to thlck bedded, slabby, ledge, calcareous, subrounded, poor sorung, duty Fowkes Format~on Sandstone, fine gralned, gray~shyellow, weath- The top 1s an eros~onalsurface ers graylsh yellow, calcareous, laminated to me- d~umbedded, ledge, spherlcal to subrounded Unit gralns, sortlng average, npple marks Unrt Thrcknesj Sandstone, same as unlt 7 except cross-bedded No. (meters) Descr~ptron and r~pplemarks 6 13 3 Conglomerate, weathers moderate brown, poorly sorted, well-rounded dark gray chert, Covered slope light gray quartzlte and gray~sh orange chert Sandstone, coarse gralned, graylsh yellow, pebbles range In slze up to 5 cm In d~ameter, weathers gray~sh yellow, calcareous, masslve, matrlx 1s poorly sorted, subrounded, poorly ce- ledge, spherlcal gralns, sortlng good, cross-bed. mented sandstone, ledge formlng, weathered dlng, poroslry good pebbly surface Covered slope Sandstone, med~umgray, weathers moderately Sandstone as above In unlr 4 except weathers brown, fine gralned, well-rounded quartz and yellow~shbrown chert gralns, well cemented, thln bedded, well Sandstone, med~umgralned, gray~shorange, sorted, ledge form~ng weathers dark yellow~shbrown, calcareous, Conglomerate, weathers moderate brown, lammated to thlck bedded, flaggy, cl~ffformlng, poorly sorted, pebbles range up to 5 cm In dl- subangular gralns, sorting average, cross-bedded, ameter, well-rounded dark gray chert, l~ghtgray dlrty quartz~teand graylsh orange chert pebbles, ma- Total 318 0 meters tnx 1s poorly sorred, subrounded, poorly ce- mented sandstone, ledge formlng, weathered pebbly surface Sectzon 2b Bear Rlver Formaoon Conglomerate, poorly sorted, poorly cemented, cobbles and pebbles range up to 0 5 m In dlam- snformable contact w~rhoverlylng Wasatch Formatlon eter, cobbles and pebbles are composed of dark gray chert, l~ghtgray quartzlte, and gray~shor- Unrt ange quarnlte, matrlx varles from gray~shor- Unrr Thrckness ange to l~ghrgray poorly cemented coarse sand- Nu (meters) stone, slope formlng 38 20 5 Shale, dark gray, weathers dark gray, slope Sandstone, coarse gralned, poorly cemented. 12 dusty yellow and yellow~shgray, thln bedded, 37 Sandstone, fine gralned, gray, weathers brown, poorly sorted, subrounded to subangular, sand thln bedded, ledge grams Include quartz, chert, b~ot~te,some clay Shale, dark gray, weathers dark gray, slope matnx, slabby, slope formlng Sandstone, fine gralned, gray, weathers brown, Conglomerate, poorly sorted, well rounded, th~n-beddedledge cobbles range up to 0 5 m In d~ameter,coarse, Lmestone, coqulna, dark brown, weathers tan, poorly cemented, salt and pepper colored sand assorted gastropods and blvalves matnx, cobbles, pebbles, and sand grams are Shale, dark gray, weathers dark gray, slope form- composed of dark gray chert, l~ghrgray quartz- Ite, graylsh orange quartzlte, and phosphate, 1% slope formlng Sandstone, coarse gralned, llght gray, weathers - brown, very thln bedded, flaggy, ledge formlng, Total 83 8 meters rounded grams w~thhemat~te spots, calcareous, Underlam by the PermIan Phosphorla Forma- weathers blocky tlon Shale, dark gray, weathers dark gray, slope forming Sectron 2 0 3 Sandstone, fine gralned, Ilght gray, weathers Bear Rlver Formaoon dark brown, very thln bedded, flaggy, ledge An ~ncompleresectlon of Bear Rlver Format~onwas measured at two lo- formlng, rounded grams w~thhemat~te spots, cales w~thlnthe Woodruff Narrows Quadrangle The upper part was measured calcareous, r~pplemarks, weathers blocky beglnnlng at a fork In the road just east of Warner Sprlng In sectlon 8, T 10 29 13 4 Shale, dark gray, slope formlng N, R 8 E, and commencing west The lower part was measured from a post at the base of the r~dgelust west 7 0 Sandstone, fine grarned, light gray, weathers of the Woodruff Narrows Reservo~rDam In sectlon 32, T 18 N, R 120 W dark brown, very thln bedded, ledge formlng, From here the sectlon was measured northwest and north Because of structural weathers blocky compl~cat~onsthe sectlon was offset until the top was finally reached In sectlon 27 32 3 Shale, dark gray, weathers dark gray, slope form- 20, T 18 N, R 120 W, where ~t 1s overlaln by the Wasatch~ormat~on Ing 26 6 2 Sandstone, fine gralned, llght gray, weathers Sectzon 2a dark brown, very rhln bedded, calcareous, hema- Bear Rlver Formatlon tlte spots Unconformable contact wlth overlying Wasatch Format~on 25 65 5 Shale, dark gray, weathers gray, slope OTT

24 10 4 Sandstone, fine gra~ned,l~ght gray, weathers 4 19 7 Srltstone, medrum gray to greenrsh gray, rh~n brown, very thin bedded, flaggy, calcareous, bedded, blocky, slopeledge, lnterbedded ol~ve r~pplemarks gray lammated shale 23 14 3 Shale, dark gray, weathers dark gray, slope 3 37 3 Covered 22 12 Sandstone, tine grarned, Irghr gray, weathers 2 10 2 Slltstone, medrum gray, th~ckbedded, blocky, dark brown, very thln bedded, flaggy. ledge. ledge form~ng,calcareous, lnrerbedded moderate rounded grams w~rhhemat~te spors, calcareous, brown lamrnated shale, and 11ght olive gray rrpple marks near top, weathers blocky shale 21 11 7 Shale, dark gray. weathers dark gray, slope 1 2 6 Shale, moderare, yellowrsh brown, lamrnared, 20 0 6 L~mestonecoqulna, brownrsh gray, weathers - slope formrng, calcareous gray~shran, sandy, th~ckbedded, flaggy, ledgy Total 170 9 meters slope, rnrerbedded wrth th~ndark gray shale. Underlarn by the Phosphona Formarlon some areas weather wh~rrsh,assorted gastropods and blvalves 19 89 1 Shale, dark gray, slope 18 2 1 hmesrone coqulna srm~larto 20 17 9 3 Shale, dark gray, weathers dark gray, slope Unrt L'nzi Thrcknerr 16 10 9 Limestone coqurna slmrlar to 20 No [meterr) Drrrrzptron I5 27 5 Shale, dark gray, slope 13 4 3 Coqu~na,medlum Irght gray cherr (more than 14 10 0 Llmesrone coqulna srmllar to 20 go%), phosphar~c, fossrls Include brvozoans, 13 73 0 Shale, dark gray, slope brach~opods, fenesrrare bryozoans, crrnords. 12 15 Llmesrone coqulna. brown~shgray, weathers ledge former, thrck bedded gray~shtan, sandy, th~ckbedded, ledge 12 6 7 Cherr, dark gray ro greenrsh black, th~nbedded. 11 2 0 Shale, dark gray, slope blocky weather~ng,ledge forming 10 5 7 Sandstone, wh~teto brown, rned~um gralned. 1 1 13 Shale, moderate yellowrsh brown to moderate weathers tan to dark brown. thln bedded, cl~ff, brown, phospharrc lam~nated,shaly, slope form- hematrte spors, plant fragments, weathers pit- rng, lnterbedded dark gray cherr, about 10 per- ted cent 9 13 6 Shale, l~ghtto dark gray, carbonaceous, sandy, 10 13 Chert, med~umgray, th~nbedded, hlghly frac- slope former tured, ledge formlng, weathers dark yellow~sh orange, over 90 percent cherr of wh~chless than 8 3 7 Sandstone, s~m~larto unit 9 except no plant 10 percent IS lnrerbedded dark gray chert fragments 9 7 6 Chert, dark gray, rhrn to med~umbedded, h~gh- 7 13 0 Covered slope of gray so11 ly fractured, ledge formrng, ~nrerbedded dark 6 2 0 Sandsrone as above yellowrsh orange, th~nbedded, fracrured shale 5 8 0 Covered slope Chert has about 5 percent wh~tesll~ca stnngers 4 3 2 Sandstone, fine grarned, l~ghtgray, weathers along bedd~ngplane dark brown, very rh~ckbedded, ledge, calc~te 8 16 7 Shale, med~umdark gray, weathers pale vellow- crystals on lolnt surfaces ~shorange on surface, very th~nbedded, slabby, 3 12 5 Covered slope sloped-ledge formrng, dark gray 3 2 mm bv 6 4 mm pelletl~keshale rnterbedded 2 4 2 Sandstone as above 7 5 8 Shale, dark gray, thrn bedded, slabby, wh~tes~l- I 11 3 Covered slope of 11ght gray so11 Ica stnngers about 3 2 mm wrde range In length Total 575 8 meters from 5 to 25 cm along the bedd~ngplane. sl~ghtlymotrled bedd~ng,ledge-formrng 6 9 2 Shale, ol~vegray, rhln bedded, slabby, slope- A roadcut leadrng to the Benlam~nMrne near the mouth of Brazer Canyon ledge formlng, lnterbedded brownrsh black. provrdes a good exposure of orherwrse covered Trrasslc Drnwoody and Permran phosphat~c,rhrn-bedded shale Phosphorla Formations The section was measured from the wesr end of the Benjamrn Mrne road near the center of secrron 18, T 11 N, R. 8 E, of the Rex 5 13 Shale, ol~veblack, lam~nated, shaly splltr~ng. Peak Quadrangle along the road toward the east, to the base of rhe Trrasslc slope former, lnrerbedded dark greenrsh gray, Woodsrde Formarlon th~n-beddedshale 4 5 5 Shale, moderate yellow~shbrown, thrn bedded, D~nwoodyFormanon flaggy weathenng, slope-ledge formlng, Inter- bedded phosphat~c,oolltrc, ol~veblack rhrn-bed- Unrt ded shale Unzt Thtckner~ 3 2 0 Shale, ollve black, lam~nated,shaly partrng No fmeters) Descrrptron slope former, Interbedded dark green~sh grav 9 12 1 Shale, and s~ltstone,medrum dark gray, weath- thrn-bedded shale ers moderate brown, th~nbedded, slabby, ledge 2 22 5 Shale, dark gray, weathers med~umdark gray. form~ng,lnterbedded dusky yellow, lrght brown rhrn bedded, slabby partrng, sloped-ledge form- weathenng srltstone ing, calcareous, phosphar~c 8 66 3 S~ltstone,sandy, med~umgray to green~shgray, 1 -176 5 Covered thrn bedded, slabby to blocky, slope formrng, Interbedded ol~vegray and moderate brown~sh Total 255 0 meters lamrnated shale Underlain by the Wells Formdtlon Shale, brown~shgray, lam~nated,shaly splrrt~ng, slope formrng, rnrerbedded green~shgray rh~n- Secf~on4 bedded s~lrsrone A conrrnuous secrron from the top of the Mrssrssrppran Lodgepole Lime- Srltstone, medlum gray, th~nbedded, slabby to stone to the top of the Pennsylvanian-Perm~an Wells Formarlon was measured blocky, slope formrng, rnterbedded olrve gray from a saddle near the cenrer of the easr half of sectron 20, T I1 N. R 8 E, (of lam~natedshale the Rex Peak Quadrangle) and In a northwesterly drrect~ondown a small can- Shale, brownrsh gray, lammared shaly splrrr~ng. yon toward rhe mouth of Brazer Canyon. The secrron ends In th~ssmall canvon slope form~ng,lnterbedded greenrsh gray th~n- about 4 km easr of the Brazer Canyon road The strata measured ~ncludesthe bedded srltstone type sectlon of M~ss~ss~pp~anBrazer Dolom~te GEOLOGY OF THE WOODRUFF NARROWS QUADRANGLE, UTAH-WYOMING

Wells Format~on Brazer Dolom~te Unc onformable contact w~ththe Wells Format~on Conformable conract wrth the overly~ngPhosphorla Format~on

Unrr Unrr Thrchne~~ Unrt Llercrrptron No. (meters) Descrzptron No 3 7 Sandsrone, dolomit~c,coarse gralned, yellow Sandstone, very lrght gray, fine gralned, fnable, gray, weathers yellow gray to l~ghtgray, thln th~nbedded, cl~ffformrng, calcareous cemenr, bedded, lamlnated slope, small ledge former, basal 0 2 m ~nrraformat~onalcalcareous sand- weathers easrly stone conglomerate, medrum dark gray to me- dlum gray, sandstone appears bleached, Inter- Covered clasrs of very angular conglomerate of gray Dolom~te,fine crystalllne, med~umllght gray cherty sandsrone whlte, weathers med~umgray, thln bedded, massrve, slope Sandstone, very Iighr gray, weathers Ilghr gray, Dolom~te,very coarse, llght ol~vegray-patchy, thln bedded, fine gralned, calcareous cemenr, breccrated, thlck bedded, rnasslve. 2 percent quartz grams, blocky weathenng, ledge former, chert, slope-small ledge former less than 2 percent chert Covered Covered Dolom~te,fine-med~um crysrall~ne, med~um Sandstone, very l~ghtgray, weathers 11ght gray, gray, weathers 11ght gray, thln bedded, massive, th~nbedded, fine gralned, cross-bedded, jointed slope former, darker near top, top has along beddlng plane and vertlcal to beddlng strlngers plane, quartz sandstone, blocky weathering, Covered ledge formrng, lrght blu~shgray chert interbeds, Sandstone, med~umgralned, l~ghtgray, weath- 01 m thlck, comprises less than 5 percent ers grayrsh orange, thin bedded, slope former, Covered "aggy Dolom~re,fine ctysralllne, l~ghrgray to wh~te Sandsrone, very 11ght gray, weathers llght gray, gray, thln bedded, masslve slope former, grades very thin to th~nbedded, jolnr wearhenng pat- Into sandstone tern produces small ( 01 to 03 m) blocky frag- Dolom~te,med~um crystallrne, med~umgray, ments, very fine quartz grams, ledge forming, weathers l~ghtollve gray, ool~tlcnear top, me- l~ghrblue gray chert in very thln layers (less d~umbedded, masslve, cllff former, 8-cm chert than 10 percent chert) layer In m~ddle Covered Dolomite, fine crystalllne, yellow gray, weathers 11ght ollve gray, thin bedded, masslve, Chert, lrght blue gray, wh~te,thln bedded, ledge and p~sol~res,ledge former, gastropods at base, formlng, overlying sandstone .burrows Covered Dolom~te,fine crystall~ne,llght ollve gray, thln bedded, masslve, small ledge, nodules of chert Sandstone, fine to medrum gralned, very thln are rare bedded, l~ghtgray, gray~sh yellow sandstone, l~ghrblursh gray chert (10-15%), layered 05 to Dolom~te,fine crystalllne, med~uml~ght gray, I m thlck, clrff formlng weathers lrghr gray, thln bedded, masslve, slope, sl~ghtlylammated at base Covered Dolom~te,medium crystalline, med~um dark Sandstone, med~umgralned, calcareous cement, gray, weathers llght ollve gray, medlum bedded, thln bedded, sloped-ledge formlng, chert Inter- massrve, cliff former, crlnoids are rare, gastro- clasrs (10-156). light blu~shgray, Irregular pods are common, calcire strlngers, burrows, no shaped chert, small oolrr~clayer In middle of unit Dolomlte, fine crystall~ne,med~um dark gray, Covered wearhers 11ghr gray, rhln bedded, massive, slope Sandstone, very tine gra~ned,cemenr sl~ghtly former, no fossils or chert calcareous, hard, ledge formlng, light gray, Dolomite, medlum fine crystall~ne,medrum weathers lrght gray, med~umbedded, weathers gray, weathers l~ghtol~ve gray, dark ollve at the wlth small ltght brown spots top, med~umbedded, massive, ledge-slope for- mer, gastropods are common, syrlngospora cor- Covered als are rare, black chert layer near top (5 cm), Sandstone, fine gralned, calcareous cement, very horn corals and crlnoids are common lrghr gray, weathers l~ghtgray, thln, cross-bed- Dolomlre, coarse crystall~ne, med~um gray. ded, some weathers gray~shorange, cl~ffform- weathers light ollve gray, medrum bedded, mas- Ing, weathers fnable, broken bedd~ng,appears slve, ledge-slope former, crlnoids are rare, chert l~kesmall blocks of intraformatronal con- IS rare glomerate Dolomrte, fine crystalllne, med~umlight gray, weathers light gray, rhln bedded, masslve, verri- Sandsrone, fine gralned, calcareous cement, very light gray, lamlnated with pale orange, weath- cal partlng, no fossils or chert, ledge former ers l~ghrgray and dark yellowish orange, Iaml- Quartz sandsrone, calcareous to dolomitrc, vew nated to th~nbedded, cross-bedded, chff form- fine gcnned, l~ghtgray, weathers gray yellow, Ing, fnable slope former, thln bedded, slabby erosional base Dolom~te,fine crystalline, medrum l~ghtgray, Sandstone, fine gra~ned,calcareous cement, very weathers l~ghtgray, thln bedded, masslve, vertr- llghr gray, weathers llght gray and graylsh yel- cal partrngs, no fossils or chert, ledge former low, chin bedded, cllff formlng, solut~onweath- er~ngproduces a rough surface, cross-bedded Dolomlre, fine crystalllne, med~umdark gray. - weathers medium gray, rhln bedded, masslve, Total 208 5 meters slope former, cr~no~ddebris IS common, small Underlam by the Brazer Dolom~te nodules or whlte chert are rare OTT

Covered. rare, lenticular and nodular chert which weath- Dolomite, medium crystalline, medium dark ers dark brown to reddish, 30 percent chert. gray, weathers medium light gray, thin bedded, *Total 396.7 meters massive, ledge former, syringopora corals are Underlain by the Devon~anThree Forks Forma- common, horn corals are rare, chert is white to tlon. brown and rare. Dolomite, medium to coarse crystalline, me- dium gray, weathers yellow gray, medium bed- *Note: This section was measured previously by Sando, Dutro, and Gere ded, massive, cliff former, are rare, syr- (1959). They position several faults within the section on the basis of paleon- ingopora corals are common, chert nodules are tological evidence. The author could find no evidence of these faults at the out- rare. crop. If they do indeed exist, the total thickness of the Brazer Dolomite is somewhat less than the measured value. Dolomite, coarse crystalline, light olive gray, weathers yellow gray, thin bedded, massive ledge former, syringopora corals are common. Sectzon 5 large spirifer and stems are Section 5 was measured on the north side of a small east-west canyon In the rare but common at the base, chert is white northeast 'A of section 14, T. 10 N, R. 7 E. The section was measured west brown. along the south-facing side of the hill and ended at the base of the Brazer Dolo- Dolomite, coarse crystalline, medium gray, mite located in a saddle 100 m east of a small hill identified as 6,942 feet on the weathers yellow gray, thin bedded, massive, cliff Woodruff Narrows Quadrangle map. former, crinoid debris is abundant, 5 percent white to dark gray chert, layered with a few nodules; syringopora corals are rare. Lodgepole Limestone Dolomite, coarse crystalline, gray yellow, weath- ers yellowish gray, thin bedded, massive, ledge Unlt former, crinoid debris is common, chert in Unit Thicknefi lenses and nodules that are white gray. No. (meters) Description Dolomite, medium crystalline, yellow gray, 15 3.0 Limestone, med~umgray, weathers light ol~ve weathers light gray (slight tint of yellow), thin gray, massive, slope forming. bedded, massive ledge former, abundant cri 9 Covered. Dolomite, fine crystalline, light gray, medium Limestone, medium gray, weathers ol~veme- bedded, massive, slope former, abundant cn- dium gray, thin bedded, slabby, slope former; noids, brachiopods are common (spirifers?), fossils include crino~ds,brachiopods, corals; oc- horn corals are rare; black chert weathers dark casional white calcite in fractures. brown to dark red with some white. Covered. Dolomite, medium crystalline, yellow gray, Limestone, dark gray, weathers dark gray and weathers yellow gray, thin bedded, massive light olive gray, thin bedded, slabby, slope ledge former, crinoids are common to abun- forming, weathers to rubble with some soil; dant, chert is nodular 4 percent. black to brown fossils include horn corals, spinfer brachiopods, color. and twiggy bryozoans Covered. Covered. Dolomite, fine crystalline, light gray color, Limestone, dark gray, weathers medium dark weathers yellow gray, thin bedded, massive, gray, thin bedded, slabby, slope forming, occa- slope former, syringopora corals are rare, horn sional white calc~rein fractures. corals are common, crinoids and brachiopods Covered are common; 10 percent chert, black, weathers Limestone, medlum dark gray to dark gray, dark brown to dark orange. weathers l~ghrdark gray and moderate vellow- Dolomite, medium crystalline, medium gray, ish brown, thin bedded, slabby, slope forming, weathers light gray, medium bedded, massive, weathers to ~bble;abundant fossils include bottom half of unit is slope, top half is ledge, horn corals and syringopora corals, spirifer and abundant crinoids, bioclasric, spirifer brachio- other assorted brachiopods, and crinoids; occa- pods are common, bryozoans are rare, syr- s~onalnodules, white calcite in fractures, 1.0 to ingopora corals are common near top of unit, 4.0 cm reddish bands at base. nodular chert (syringopora corals inside no- Covered. dules) 5 to 10 percent. Limestone, dark gray, weathers dark yellowish Dolomite, medium to coarse crystalline, me- brown ro dark gray, rhln bedded, slope forming, dium gray, weathers yellow gray, thin bedded. slabby; fossils include brachiopods, cr~no~ds, massive ledge former, abundant crinoids, fetid bryozoans. odor, 5 percent nodular white to gray chert. Covered. Dolomite, medium crystalline, medium gray, weathers yellow gray, medium bedding, mas- Limestone, light gray, weathers light gray to sive, slope-ledge former, bioclastic in part, abun- medium dark gray, thin bedded, slabby, ledgy dant crinoids and bryozoan-cryprostomata(?); slope, weathers to rubble, occasional carbonate nodular chert white to gray, 10 percent. nodules with some silica whlch weathers mod- erate brown, white calclre In fractures; fossils Dolomi te, medium to coarse crystalline, light include corals, gastropods, crinoids, and bvo- gray, weathers medium light gray, thin bedded, zoans; layered chert, dark gray 1.0 to 3.0 cm massive cliff-ledge former, splrifer brachlopods thick near base. (large, rare), bioclastic in parr, abundant cri- Covered. noids, horn corals are rare; 5 percent chert, lay- ered, light gray to white. Limestone, crystalline, dark gray. weathers dark gray, thin bedded, white calc~tefilling in frac- Dolomite, fine crystalline, medium gray, weath- tures, weathers to rectangular blocks, ledgy ers light to medium gray, thin bedded, massive slope. slope.ledge, cnnoidal, chert-lenticular, grades into dolomi re, medium stained, medium gray, Total 166.8 meters weathers light gray, thin bedded, masslve, ledge, Stratigraphic contact w~ththe underlving Three abundant crinoids, cryptostomata bryozoans are Forks Formation. GEOLOGY OF THE WOODRUFF NARROWS QUADRANGLE, UTAH-WYOMING 83

Section 6 7 52.8 Dolomite, fine crystalline, light gray, wearhers The Three Forks Formation and the Jefferson Formation were measured in lighr gray, medium thick bedded, ledge, frac- the north central part of section 11, T. 10 N, R. 7 E. Measurements were taken tures have calc~recrystals and iron oxide stains. west of a ridge top about .4 km south of a jeep trail near the northern boundary 6 25.3 Dolomite similar ro unit 7 except gray on fresh of section 11 su dace. 5 13.9 Dolomire, medium coarse crysralline, pinkish Three Forks Formarion gray to lighr gray, wearhers light gray to red- Stratigraphic contacr wirh the overlying Lodgepole Limestone. dish gray, rhin bedded, ledge-slope. 4 0.1 Limestone, very light gray, weathers reddish yel- Unit low, very rhin bedded, some fractures have Unit Thirknerr spots of green copper(?) mineralization. No. (meters) Dercription 3 28.9 Dolomite, fine to coarse crystalline, light gray, 2 62.5 Covered. Floar is reddish sandstone, limestone, weathers l~ghtgray, rhick to very rhick bedded, and sandy limestone. cliff. 1 24.6 Sandstone, medium coarse, moderate reddish or- 2 22.4 Dolomite, coarse crystalline, dark gray, weathers ange to dark yellowish orange; thin bedded, medium gray, massive, cliff. flaggy, grains are spherical to rounded, good 1 19.0 Dolomite, medium crystalline, gray, weathers - sorting, alternating light to moderate red bands. light gray, massive, ledge-slope, tight breccia Total 87.1 meters - recemenred wirh calcite. Gradational contact with the underlying Jeffer- Total 236.4 meters son Formation. REFERENCES CITED Jefferson Formation Armstrong, F. C., and Oriel, S. S., 1965, Tectonic development of the Idaho- Wyoming thrust belr: American Associarion of Geologists Unit Bulletin, v. 49, no. 11, p. 1847-66. Unit Thirkne~s No. (meters) Dercription Armstrong, R. L., 1968, The Cordilleran miogeosyncline in Nevada and Utah. Urah Geological and Mineralogical Survey Bullerin 78, p. 38. 10 21.8 Dolomire, crystalline, dark gray, weathers dark Berdan, J. M., and Duncan, H., 1955, Ordovician age of the rocks mapped as yellowish brown, massive, ledge forming, white Silurian in wesrern Wyoming: Wyoming Geological Association Guide- dolomite stringers along fractures. book 10th Annual Field Conference, 1955, p. 48. 9 9.5 Covered. Bissell, H. J., 1974, Tectonic control of late Paleozoic and early Mesozoic sedi- 8 1.2 Lmestone, crystalline, moderate red, wearhers mentation near the hinge line of the Cordilleran miogeosynclinal belr: Se pale red, rhick bedded, blocky, slope forming. ciety of Economic Paleontologists and Mineralogists Special Publication 7 5.2 Covered. no. 22, p. 83-97. 6 1.6 Dolomite, crystalline, dark gray, weathers Blackwelder, E., 1918, New geological formations in western Wyoming: Wash- brownish gray, thin bedded, slope forming. ington [D.C.] Academy of Sciences Journal, v. 8, p. 425. 5 21.5 Covered. Boutwell, J. M., 1907, Stratigraphy and structure of the Park City mining dis- 4 3.0 Dolomite, medium gray, weathers light gray, tncr, Utah: Journal of Geology, v. 15, p. 439-58. crysralline, blocky, thick bedded, slope-ledge Collier, A. J., and Cathcarr, S. H., 1922, Poss~bilityof finding oil in laccolirhic former. domes south of the Litrle Rocky Mountains, Montana: U.S. Geological Survey Bulletin 736-F, p. 173. 3 13.7 Covered. Condir, D. D., 1916, Relations of the Embar and Chugwarer Formations in cen- 2 17.3 Dolomite, ledgy slope former. tral Wyoming: U.S. Geological Survey Professional Paper 98, p. 263. 1 13.5 Dolomire, crystalline, dark gray, wearhers dusky Eardley, A. J., 1967, Idaho-Wyoming fold and thrust belr: Its divisions and an brown, massive ledge former, weathers to soil analysis of irs orig~n:Intermountain Association of Geologists 15th An- and rubble, contact with underlying unir is nual Field Conference, p. 35-44. - good. Hayden, F. V., 1869, Preliminary field reporr of the U.S. Geological Survey of Total 108.3 meters and New Mexico, 3rd annual reporr, p. 91-92. Unconformable conract with the underlying Hayden, F. V., Peale, A. C., and Gannerr, H., 1872, Preliminary report of the Ordovician Fish Haven Dolomite. U S. Geological Survey of Montana and portions of adjacent Territories, 5th annual reporr, p. 100-56. Section 7 , 1879, Eleventh annual reporr of rhe U.S. Geological and Geo- The Fish Haven Dolomite was measured northwest from the Fish Haven- graphical Survey of the Territories, embracing Idaho and Wyoming, Brazer thrust contacr near the sourhern boundary of section 11, T. 10 N, R. 7 being a report of exploration for the year 1877, p. 573-710 E. The beginning point was in a saddle along the ridge just south of a resistant , 1883, Twelfth annual report of rhe U.S. Geological and Geo- knob of Brazer Dolomite graphical Survey of the Territories, a report of progress of the exploration in Wyoming and Idaho for the year 1878. In two parts; part 2. Fish Haven Dolomite King, C., Emmons, S. F., and Hague, A,, 1878, U.S. geological exploration of Unconformable conract wirh the overlying Jefferson dolomite the fortieth parallel reporr, v. 2, p. 326-39, 393-442, atlas. McKelvey, V. E., Williams, J. S., Sheldon, R. P., Cressman, E. R., Cheney, T. Unit M., and Swanson, R. W., 1956, Summary descriprion of Phosphoria, Park Unit Thlckners Ciry, and Shedhorn Formations in wesrern phosphate fields: American As- No. (meterr) Dercr~pdon sociation of Petroleum Geologists Bullerin, v. 40, no. 12, p. 2826-63. Moritz, C. A,, 1953, Summary of the Cretaceous stratigraphy of southeastern 11 4.0 Limestone, medium coarse crystalline, sandy, Idaho and western Wyoming: Inrermounrain Association of Petroleum white at base and gray ar cop, massive, ledge- slope, upper part has dark gray angular dolo- Geologists Guidebook, 4th Annual Field Conference, p. 69. mite clasts which average 1 cm. Peale. A. C., 1893, The Paleozoic section in the viciniry of Three Forks, Mon- tana: U.S. Geological Survey Bullerin 110, p. 56. 10 33.5 Dolom~te,medium crystalline, gray, wearhers Richards, R. W., and Mansfield, G. R., 1912, The Bannock overthrust, a major light gray, very rhick bedded to massive, cliff. faulr in sourheastern Idaho and northeastern Urah: Journal of Geology, v. 9 1.6 Dolomite similar to unit 10 except fine crystal- 20. p. 683-84. line. Richardson, G. B., 1913, The Paleozoic section in northern Utah: American 8 34.9 Dolomire, coarse crystalline, gray, weathers Journal of Science, 4th series, v. 36, p. 406-16. gray, very thick bedded ro massive, cliff, poorly , 1941, Geology and mineral resources of the Randolph Quad- preserved crinoidal debris. rangle, Utah-Wyoming: U.S. Geological Survey Bulletin 923, p. 55. Royse, F , Warner, M A, and Reese, D L, 1975, Thrust belt srructural geome- Sloss, L L, and Hamblln, R H , 1942, Stratigraphy and insoluble res~duesof try and related strar~graphicproblems Wyoming-Idaho-Northern Utah the Madison Group (Miss~ss~pp~an)of Montana Amer~canAssociation of Rocky Mountain Assoc~at~onof Geolog~stsSymposium, p 41-54 Petroleum Geolog~stsBulletin, v 26, no 3, p 305-35 Rubey, W W, 1973, New Cretaceous formations In the western Wyomlng Sloss, L L, and Lard, W M, 1947, Devonian system in central and north- thrust belt US Geological Survey Bulletin 1372.1, 35p western Montana Amencan Assoc~at~onof Petroleum Geolog~stsBulle- tin, v 31, no 8, p 1404-30 Rubey, W W,Oriel, S S, and Tracey. J 1, 1975, Geology of the Sage and Stewart, J H , and Poole, F G, 1974, Lower Paleozo~cand uppermost Pre- Kemmerer 15-m~nutequadrangles, Lncoln County, Wyoming U S Geo- Cordilleran miogeocl~ne,Great Basln, western United States logical Survey Professional Paper 855, 18p Soc~ety of Economic Paleontolog~sts and Mlneralog~sts Spec~al Pub. Sando, W J , Dutro, J T , Jr , and Gere, W C , 1959, Brazer Dolomite (MIS- l~catlonno 22, p 28-57 siss~ppian),Randolph Quadrangle, northeast Utah Amer~canAssoc~at~on Veatch, A C, 1907, Geography and geology of a portlon of southwestern of Petroleum Geologists Bulletin, v 43, no 12, p 271-69 Wyomlng U S Geological Survey Professional Paper 56