BRIAN J. BOYLE COMMISSIONER OF PUBLIC LANDS STATE OF WASHINGTON
ART STEARNS, Supervisor RAYMOND LASMANIS, State Geologist DEPARTMENT OF NATURAL RESOURCES DIVISION OF GEOLOGY AND EARTH RESOURCES
GEOLOGY OF THE GRANDE RONDE LIGNITE FIELD,
ASOTIN COUNTY, WASHINGTON
By Keith L. Stoffel
Report of Investigations 27
1984 BRIAN J. BOYLE COMMISSIONER OF PUBLIC LANDS STATE OF WASHINGTON
ART STEARNS, Supervisor RAYMOND LASMANIS, State Geologist DEPARTMENT OF NATURAL RESOURCES DIVISION OF GEOLOGY AND EARTH RESOURCES
GEOLOGY OF THE GRANDE RONDE LIGNITE FIELD,
ASOTIN COUNTY, WASHINGTON
By Keith L. Stoff el
Report of Investigations 27
Printed in the United States of America
1984
For sale by the Department of Natural Resources, Olympia, Washington Price $4.00
CONTENTS
Page
Abstract t • t t Ott t t t t t I It t t t t t too It Ott It t It t It t t t Ott t t t t t t t I t t I It t It t t It 1 Introduction ...... 2 Location and geographic setting ...... 2 Purpose and scope of study ...... 3 Methods of study ...... 3 Acknowledgments ...... 4 Geology of the Columbia Plateau ...... 6 General geologic setting ...... 6 Stratigraphic nomenclature ...... 7 Columbia River Basalt Group ...... 7 Ellensburg and Latah Formations ...... 8 Stratigraphy ...... 8 Regional stratigraphy ...... 8 Imnaha and Picture Gorge Basalts ...... 8 Yakima Basalt Subgroup ...... 9 Grande Ronde Basalt ...... 9 Wanapum Basalt ...... 9 Saddle Mountains Basalt ...... 10 Stratigraphy of the Grande Ronde lignite field ...... 11 Structure ...... 13 Evolution of the Blue Mountains province ...... 13 Structural geology of the Grande Ronde River-Blue Mountains region ...... 15 Folds ...... 15 Faults ...... 15 Age of tectonism ...... 16 Geology of the Washington State portion of the Grande Ronde lignite field ...... 16 Description of stratigraphic units ...... 16 Basalt flows ...... 16 Umatilla Member ...... 17 Field characteristics ...... 17 Petrography ...... : ...... 18 Chemistry ...... 19 Elephant Mountain Member ...... 19 Tule Lake flow ...... 19 Whitetail Butte flow ...... 20 Field characteristics ...... 21 Petrography ...... 21 Chemistry ...... , ...... 22 Radiometric age dates ...... 22
III Page
Geology of the Washington State portion of the Grande Ronde lignite field - Continued Description of stratigraphic units - Continued Basalt flows - Continued
Buford Member ...... 24 Mountain View flow ...... 24 Medicine Creek flow ...... 24 Field characteristics ...... 25 Petrography ...... 26 Chemistry ...... 26 Sedimentary interbeds ...... 26 Grouse Creek sedimentary interbed ...... 27 Menatchee Creek sedimentary interbed ...... 27 Interbed constituents ...... 27 Source of interbed sediments ...... 28 Grande Ronde lignites ...... 28 Distribution and thickness ...... 28 Quality ...... 30 Depositional environment ...... 30 Discussion of complex stratigraphic relationships ...... 31 Sediment deposition ...... 31 Development of the Troy basin ...... 31 Flow surface topography ...... 33 Sediment destruction ...... 34 Invasive flows ...... 34 Canyon cutting ...... 36 Folding ...... 37 Development of benches ...... 38 Summary ...... 40 Geologic history ...... 40 Lignite reserves and suggestions for exploration ...... 41 References cited ...... 43 Appendix A - Sample locations ...... 4 7 Appendix B - Basalt geochemistry ...... 55 Geochemical data ...... 58 Variation diagrams ...... 60 Appendix C - Grain size analyses of sediments ...... 67 Grain size distribution curves ...... 69 Appendix D - Clay mineralogy of sediments ...... 71 X-ray diffraction patterns ...... ·...... 7 3
IV ILLUSTRATIONS
Page
Plate 1. Geologic map of the Grande Ronde lignite field, Asotin County, Washington ...... In pocket
Figure 1. Location of the Grande Ronde lignite field and the study area of this report ...... 2 2. View of the Washington State portion of the Grande Ronde lignite field from the Blue Mountains ...... 3 3. Schematic cross section of the Washington State portion of the Grande Ronde lignite field ...... 4 4. Physiographic provinces of Washington and Oregon ...... 5 5. Generalized map of the northwestern United States, showing distribution of Columbia River Basalt Group ...... 6 6. Comparison of Columbia River Basalt Group stratigraphic nomenclature ...... 7 7. Correlation of the formalized stratigraphic nomenclature of the Columbia River Basalt Group with the informal nomenclature of the Saddle Mountains Basalt in the Grande Ronde River-Blue Mountains region ...... 9 8. View from the northwest of the steeply dipping south limb of the Slide Canyon monocline ...... 10 9. Generalized structure map of northeastern Oregon and adjacent Washington ...... 11 10. Proposed stratigraphy of the Saddle Mountains Basalt in the Washington State portion of the Grande Ronde lignite field ...... 12 11. Schematic cross section of the Blue Mountains ...... 13 12. Structure map of the Grande Ronde River-Blue Mountains region .... 14 13. Cross section through the Grande Ronde River- Blue Mountains region ...... 14 14. Map of the Grande Ronde Fault System ...... 15 15. Photograph of the Sillusi flow in Grouse Creek ...... 17 16. Photomicrograph illustrating the microporphyritic texture of the Sillusi flow ...... 18 17. Proposed type locality of the Tule Lake flow (Elephant Mountain Member) ...... 19 18. Proposed type locality of the Whitetail Butte flow (Elephant Mountain Member) ...... 20 19. The Whitetail Butte flow on the east side of "The Bench" ...... 21 20. View of the cliffs at the head of Grouse Creek ...... 22 21. Complex, chaotic jointing of the Whitetail Butte flow in the cliff at the head of Grouse Creek ...... 23
V Page
Figure 22. Photomicrograph illustrating the equigranular texture of the Whitetail Butte flow ...... 24 23. View across Menatchee Creek to the proposed type localities of the Mountain View flow (Buford Member) ...... 25 24. Proposed type locality of the Medicine Creek flow {Buford Member) ...... 26 25. Photomicrograph illustrating the microporphyritic texture of the Mountain View flow ...... 27 26. View of McLaughlin Spring and two ocher unnamed springs ...... 29 27. Probable drainage pattern in the Grande Ronde River- Blue Mountains region during early Saddle Mountains Basalt time ...... 31 28. Probable drainage pattern in the Grande Ronde River Blue Mountains region during accumulation of the thick peat {now lignite) at the base of the Grouse Creek sedimentary interbed ...... 32 29. Probable drainage pattern in the Grande Ronde River- Blue Mountains region during middle Saddle Mountains Basalt time ...... 33 30. Invasive flow of the Elephant Mountain Member exposed in a borrow pit on Grouse Flat ...... 34 31. Photograph of small basalt hills on the south end of "The Bench" ...... 35 32. Details of the small basalt hills shown in fig. 31 ...... 36 33. View southwest to a linear ridge of basalt of the Mountain View flow ...... 37 34. View of McLaughlin Spring ...... 38 35. Invasive dike of the Whitetail Butte flow ...... 39 36. View of a broad bench eroded into the Grouse Creek interbed on the east side of Grouse Creek ...... 40 37. Basalt and sediment sample locations map ...... 52 38. Basalt and sediment sample locations map ...... 53 39. Basalt and sediment sample locations map ...... 54 40. Ti02/P2o5 diagram of basalt flows in the Grande Ronde lignite field ...... 6 0 41. P2o5/Si02 diagram of basalt flows in the Grande Ronde lignite field ...... 61 42. Ti02/Si02 diagram of basalt flows in the Grande Ronde lignite field ...... 62 43. K 20/Si02 diagram of basalt flows in the Grande Ronde lignite field ...... 63 44. CaO/Si02 diagram of basalt flows in the Grande Ronde lignite field ...... 64
VI Page
Figure 45. MgO/Si02 diagram of basalt flows in the Grande Ronde lignite field ...... 6 5 46. Grain size distributions for samples GRS-3, GRS-18, GRS-24, and GRS-25 ...... 70 47. X-ray diffraction pattern of sample GRS-1 ...... 73 48. X-ray diffraction pattern of sample GRS-2 ...... 74 49. X-ray diffraction pattern of sample GRS-3 ...... 7 5 50. X-ray diffraction pattern of sample GRS-4 ...... 76 51. X-ray diffraction pattern of sample GRS-5 ...... 77 52. X-ray diffraction pattern of sample GRS-6 ...... 78 53. X-ray diffraction pattern of sample GRS-7 ...... 78 54. X-ray diffraction pattern of sample GRS-8 ...... 79 55. X-ray diffraction pattern of sample GRS-9 ...... 79 56. Cross section A to A'...... Plate 1 57. Cross section B to B' ...... Plate 1 58. Cross section C to C' ...... Plate 1 59. Cross section D to D'...... Plate 1 60. Cross section E to E' ...... Plate 1 61. Cross section F to F' ...... Plate 1 62. Cross section G to G' ...... Plate 1 63. Cross section H to H'...... Plate 1 64. Cross section I to I' ...... Plate 1 65. Cross section J to J' ...... Plate 1 66. Cross section K to K'...... Plate 1 67. Cross section L to L' ...... Plate 1 68. Section M ...... Plate 1 69. Section N ...... Plate 1 70. Section O ...... Plate 1 71. Section P ...... Plate 1
TABLES
Page
Table 1. Analyses of Grande Ronde lignites ...... 30 2. Basalt and sediment sample locations ...... 49 3. Major and minor oxide data for Columbia River Basalt Group flows in Gra.nde Ronde lignite field, Asotin County, Washington ...... 58
VII
GEOLOGY OF THE GRANDE RONDE LIGNITE FIELD,
ASOTIN COUNTY, WASHINGTON
By Keith L. Stoffel
ABSTRACT
In the Grande Ronde River-Blue Mountains flows, which controlled subsequent region of southeastern Washington and adjacent accumulation of sediments and peat. Oregon, lignite beds up to 40 ft (12 m) 3. Some of the sediments and peat origi thick comprise part of two sedimentary interbeds nally deposited were eroded by streams which are intercalated with flows of the Miocene prior to burial by subsequent flows. Columbia River Basalt Group. Lignites analyzed 4. Some of the sediments and peat origi range from 5,027 to 7,944 Btu/lb (as received) nally deposited were destroyed or with low sulfur and moderate ash contents. displaced during the extrusion of The sediments and peat (later converted to subsequent invasive basalt flows. lignite) accumulated between approximately 13.5 5. Following the cessation of volcanism, and 10 million years ago, during a period of the basalt flows and intercalated regional structural deformation punctuated by sedimentary interbeds were folded and sporadic eruptions of basalt flows. This period eroded along the northern margin of was highlighted by the events listed below. the Troy basin. 1. Sediments accumulated in the develop 6. During post-volcanism downcutting by ing Troy basin, a structural and topo the Grande Ronde River and its tribu graphic depression which formed south taries, some of the interbed sediments and east of the Blue Mountains uplift. were reworked and redeposited, prob The tectonic evolution of this basin ably destroying portions of some lignite controlled both epiclastic sediment beds in the process. deposition and peat accumulation. These events produced complex stratigraphic 2. Vents for some of the basalt · flows relationships between Columbia River Basalt intercalated with the sediments were Group flows and intercalated sediments. Future located within the lignite field itself, exploration for lignite in the Grande Ronde lig producing constructional topographic nite field must be based upon a thorough under relief on the surface of some of the standing of these stratigraphic complexities. 2 Geology of the Grande Ronde Lignite Field
INTRODUCTION
LOCATION AND GEOGRAPHIC SETTING mately 10 miles (16 km) and crops out on a series of flat to gently rolling benches 1,300 to 2,300 ft The Grande Ronde lignite field is located in (400 to 700 m) above the Grande Ronde River Asotin County of southeastern Washington and (fig. 2 and plate 1). These benches, which repre Wallowa County of northeastern Oregon. It lies sent the topographic expression of thick sedi along the southeastern slopes of the Blue Moun mentary interbeds between basalt flows, have tains and surrounds the Grande Ronde River been deeply dissected into smaller, isolated canyon (fig. 1). The Washington State portion benches by the downcutting of Cougar, Cotton of the field ( the study area of this report) stretches wood, and Menacchee Creeks (fig. 3). Since all northeastward from Troy, Oregon for approxi- lignites in the study area occur within the bench-
11HIO z l> G)lI - 110
~ I ater Ri'ler : cieor w
GRANDE RONDE t Pendl• eton LIGNITE FIELD N I
0 5 ,p . 'r 2,0 mi1u I I l I I J 0 5 10 20 30 kilometerc
FIGURE 1. - Location map of the Grande Ronde lignite field (lined) and the study area of this report (stippled). Methods of Study 3
Southern slopes of the Grande Ronde River canyon Blue Mountains
FIGURE 2. - View of the Washington State portion of the Grande Ronde lignite field from the Blue Mountains. forming sedimentary interbeds, lignite often lies relationships between Columbia River Basalt at or near the surface. Exposure of sediments and Group flows and intercalated sediments. Success lignite on the benches is very poor; outcrops are ful exploration for lignite, as well as accurate limited to scattered roadcuts and streamcuts. estimation of lignite reserves, depends u pan The benches in the Washington State portion recognition of these complex stratigraphic rela of the lignite field are all accessible by well tionships and a thorough understanding of the maintained gravel roads. With the exception of a region's geologic evolution. few scattered parcels of state-owned land, the This report supersedes the Division 0.f benches are privately owned. At the time of this Geology and Earth Resources Open-File Report writing, several tracts of private land are under 81-6 (Stoffel, 1981), a preliminary report on the lease for coal exploration. geology of the Grande Ronde lignite field.
PURPOSE AND SCOPE OF STUDY METHODS OF STUDY
This report describes the stratigraphic and Field mapping for this study was done dur tectonic evolution of the Grande Ronde River ing the summer and fall field seasons of 1980- Blue Mountains region and its control on the 1982. Portions of five 7¥2-minute topographic distribution, thickness, and quality of lignite quadrangles (Mountain View, Saddle Butte, beds in the Grande Ronde lignite field. Emphasis Diamond Peak, Troy, and Eden) were mapped is placed upon defining the complex stratigraphic (plate 1). The remanent magnetic polarity of 4 Geology of the Grande Ronde Lignite Field
SW NE
Grouse Flat Mountain View Bench Mcloughlin - Swank Bench Mallory Ridge "'.. ~ (.) "'.. 't) 0 ~ 0 (.) ;: C ..a, ::, B 4000' 0 0 (.) (.) 3500'
. . . ..,;: : :· ~:.: ,.;:.:.:. ~·~::::· .:;': ,;; •:.·: ...... ~ . .. < 2500'
2000·
1500'
lli2J Sedimentary interbed
.1 D Flows of the Columbia River Basalt Group
4x VERTICAL EXAGGERATION
0 3 4 s
MILES
FIGURE 3. - Schematic cross section of the Washington State portion of the Grande Ronde lignite field, showing several topographic benches underlain by thick sedimentary interbeds. each of the basalt flows in the study area was contributed financial and( or) technical support determined using a field fluxgate magnetometer. for this investigation: Thin sections of 91 basalt samples were studied. All but two of the samples were analyzed The ranchers in the Grande Ronde River by the X-ray fluorescence method (Hooper, region, especially Mike Odom (4-0 Cattle 1981) for oxides of Si, Al, Ca, Mg, Ti, P, Na, Mn, Company) and Bill Goodall, graciously and total Fe. Two additional basalt samples were allowed access to their land. collected and sent to a commercial laboratory for potassium-argon age dating. Rockwell Hanford Operations and the Grain size analyses and heavy mineral separa Washington State University Geology De tions were performed on 4 sediment samples. partment provided funds for some of the X-ray diffraction analyses of the < 2 micron X-ray fluorescence analyses, which were fraction of nine other sediment samples were also performed under the direction of Peter performed. Hooper at the Washington State University Basalt Research Laboratory.
ACKNOWLEDGMENTS Bonnie Bunning, Peter Hooper, Bill Phillips, Steve Reidel, Martin Ross, and Terry Tolan The author is grateful to the following reviewed the manuscript and offered many individuals and organizations who generously stimulating ideas and concepts. Physiographic Provinces 5
FIGURE 4. - Physiographic provinces of Washington and Oregon. From Franklin and Dyrness, 1973. 6 Geology of the Grande Ronde Lignite Field
GEOLOGY OF THE COLUMBIA PLATEAU
GENERAL GEOLOGIC SETTING istics distinguish the Blue Mountains province from the adjacent Columbia Basin province, The Grande Ronde lignite field lies within which is a structural and topographic depression. the Blue Mountains province, a region character Together the two provinces comprise one ized by isolated high mountain ranges separated of the earth's youngest tholeiitic basalt plateaus, by broad structural valleys (fig. 4). In Washington, ch e Columbia Plateau, which formed between the province is comprised of a broad northeast 17. 5 and 6 millions years ago (Watkins and Baksi, trending anticlinal arch, dominated by narrow, 1974; McKee and others, 1977; McKee and others, flat-topped ridges and deep, precipitous canyons. 1981; Long and Duncan, 1982). The plateau is These structural and geomorphologic character- comprised of approximately 120 to 150 individual
L..r·.-·, . Astoria ·, J I I I
I J I KILOMETERS I 0 75 150 I 0 50 ,oo OREGON I MILES
FIGURE 5. - Generalized map of the northwestern United States, showing distribution of the Columbia River Basalt Group (dark black lines). Extent of the most prominent vent system, the Chief Joseph dike swarm, is shown by pattern. Locations of the Monument dike swarm and Ice Harbor vent system are also shown. After Anderson and others, in preparation. Columbia River Basalt Group 7 flows of the Columbia River Basalt Group (Hooper, cu miles (700 cu km), (Swanson and Wright, 1982; Swanson and Wright, 1978), which erupted 1978). from north- northwest-trending linear fissures (fig. 5), (Waters, 1961;Taubeneck, 1970;Swanson and others, 197 5). Near the center of the plateau, STRATIGRAPHIC NOMENCLATURE flows of the Columbia River Basalt Group and intercalated epiclastic and volcaniclastic sediments COLUMBIA RIVER BASALT GROUP attain an estimated maximum thickness of 14,750 ft (4,500 m), (Reidel and others, 1982). Russell (1901) coined the name "Columbia Individual basalt flows range from a few ft River basalt" and defined it to include all Eocene (m) to greater than 300 ft ( 91 m) in thickness to Recent basaltic lavas of the Pacific Northwest. (Swanson and others, 1979). They average 90 to Waters (1961) proposed revising the name 120 ft (22 to 36 m) thick. Individual flows to the "Columbia River Basalt Group" and reach maximum thickness where they filled restricted its use to Miocene basalts in Washing structural depressions or river canyons. Volumes ton, Oregon, and Idaho (fig. 6). He also divided of individual flows average from 2 to 6 cu miles the group into two formations (Yakima and (10 to 29 cu km) and attain a maximum of 145 Picture Gorge Basalts) and identified four dike
Waters (1961) Wright and others ( 1973) Swanson and others ( 1979)
Upper Yakima Basalt flows Saddle Mountains Basalt at Ice Harbor Dam Lower Monumental Member Ice Harbor Member Buford Member Ward Gap and Q. :::) Elephant Mountain Member Elephant Mountain Basalt 0 Pomona Member a: Q. (!) ... of Schmincke (1967) :::) Esquatzel Member ~ 0 IXl"' a: ., (!) Weissenfels Ridge Member E IXl :;; I- :::) Asotin Member ., .; ...J en < Pomona Basalt Wilbur Creek Member I- >- !§ en ...J < < -...0 -2 IXl of Schmincke (1967) Umatilla Member• en C ~ I- < ...J CD ·~., Middle Yakima Basalt ;,,
Picture Gorge Picture Gorge Basalt Picture Gorge Basalt Basalt Lower basalt of Bond ( 1963) lmnaha Basalt
"Umatilla Member redefined as the oldest subdivision of the Saddle Mountains Basalt.
FIGURE 6. - Comparison of Columbia River Basalt Group stratigraphic nomenclature. 8 Geology of the Grande Ronde Lignite Field swarms which he believed represented vent sys ( 1901) named these sediments the Ellensburg tems for the Columbia River Basalt Group flows. Formation. Later workers excluded the supra The advent and widespread use of paleo basalt sediments from the formation and re magnetics and rapid X-ray fluorescence analyses assigned them to other formations. In subsequent in the middle to late 1960's greatly increased the studies, workers proposed restricting the Ellens field geologist's ability to identify individual burg Formation only to sediments intercalated ( or small groups of) Columbia River basalt flows. with flows of the Saddle Mountains Basalt Forma When mapping and correlation of flows became tion (Mackin, 1961) or to sediments interbedded routine, Wright and others (1973) proposed a new with both the Wanapum and Saddle Mountains informal four-fold stratigraphic subdivision of the Basalts (Smith, 1903; Waters, 1955; Schmincke, Columba River basalt (fig. 6). 1964). Waitt ( 1979) recently proposed redefining A proliferation of geologic investigations the Ellensburg Formation to include sediments occurred in the mid-1970's, resulting in the iden interbedded with all formations of the Columbia tification of several new flows. The stratigraphic River Basalt Group, as well as some sediments nomenclature became a mixture of formal and underlying the Group. informal names, requiring a comprehensive re Pardee and Bryan (19 26) first assigned vision. Utilizing some old names and introducing sediments underlying the Columbia River basalts some new ones, Swanson and others (1979) in the northeastern portion of the Columbia formally revised the nomenclature (fig. 6). As Plateau to the Latah Formation. Kirkham and suggested by Griggs (1976), they restricted the Johnson (1929) later proposed expansion of the Columbia River Basalt Group to include all formation to include sediments intercalated with extrusive volcanic rocks previously assigned to the Columbia River Basalt Group, and Hosterman the Columbia River basalt, and to exclude all ( 1969) suggested inclusion of suprabasalt sedi formations that are largely nonbasaltic. They ments as well. Griggs ( 1976) pro posed limiting also subdivided the group into 1 subgroup, 5 the use of the name "Latah Formation" to the formations, and 14 members. Spokane River drainage only. At the present time, most workers have adopted this informal nomenclature scheme. ELLENSBURG AND LATAH FORMATIONS Sediments underlying and intercalated with flows of the Columbia River Basalt Group in the Epiclastic and volcaniclastic sediments inter Spokane River drainage only are assigned to the bedded with, and overlying, flows of the Columbia Latah Formation. Elsewhere on the Columbia River Basalt Group were first studied on the Plateau, similar sediments are assigned to the western margin of the Columbia Plateau. Smith Ellensburg Formation.
STRATIGRAPHY
REGIONAL STRATIGRAPHY Formation (fig. 7). This 17.0 to 17.5 million year-old formation (McKee and others, 1981), probably underlies the entire region, but it only IMNAHA AND PICTURE GORGE BASALTS crops out in the deepest canyons ( Shubat, 1979; Swanson and others, 1980). Picture Gorge The oldest Columbia River Basalt Group Basalt flows do not crop out in the region; they flows in the Grande Ronde River-Blue Mountains are restricted to north-central Oregon ( Swanson region have been assigned to the Imnaha Basalt and others, 1979). Yakima Basalt Subgroup 9
Magnetic FORMATION AGE MEMBER polarity BUFORD flow of Walker (1973) 6.0m.y. lower Monumental N 0.. 0.. Unnamed ::, ::, Ice Harbor N,R 0 ... 0 sedimentary interbed ...J a: Buford R <( a: (!) of Ross ( 19781 (!) a> SADDLE - ::, Elephant Mountain N,T ------/ ~ co CJ> Pomona R MOUNTAINS WENAHA flow of Walker (19731 ... Esquatzel N ...J BASALT Weissenfels Ridge N <( ... CJ> CJ> ...J Asotin N GROUSE <( <( ,S. EDENflow ~ co CJ> of Ross ( 19781 <( <( Wilbur Creek N CREEK ... a> z 14.0m.y. Umatilla N sedimentary interbed of Ross ( 1978) ::, I~ - - - 0 Priest Rapids R3 - - ~ a: <( WANAPUM T,R ' PUFFER BUTIE flow of Gibson (1969) UJ Roza 3 ' ~ ~ a: :,,! BASALT Frenchman Springs N7 ' <( ' 15.Sm.y. Eckler Mountain N2 ' UJ >- ' BEAR CREEK flow of Ross (1978) ...J GRANDE 0 N2 ' C RONDE ' <( <( BASALT R2 CJ> a> PICTURE! Nl SQUAW CANYON ~ GORGE ::, 17.0 m.y. Rl sedimentary interbed of Ross (1978) ...J BASALT 0u T IMNAHA No BASALT 17.Sm.y. Ro
(after Swanson and others, 19791
FIGURE 7. - Correlation of the formalized stratigraphic nomenclature of the Columbia River Basalt Group (left) with the informal nomenclature of the Saddle Mountains Basalt in the Grande Ronde River-Blue Mountains region. N is normal magnetic polarity; R, reversed; and T, transitional. Polarity intervals are numbered sequen tially, oldest to youngest, for the Imnaha through Wanapum Basalts. Polarity intervals are not numbered in the Saddle Mountains Basalt. Radiometric age dates from Watkins and Baksi, 1974; McKee and others, 1977; McKee and others, 1981; and Long and Duncan, 1982.
YAKJMA BASALT SUBGROUP lignite field ( fig. 8 and plate 1). Uniform field, petrographic, and chemical GRANDE RONDE BASALT characteristics make identification of individual flows in the Grande Ronde Basalt difficult. For The Grande Ronde Basalt is the oldest tunately, remanent magnetic polarities of the formation of the Yakima Basalt Subgroup. flows can be used to subdivide the Grande Ronde Flows of Grande Ronde Basalt erupted from Basalt into four informal magnetostratigraphic north- northwest-trending linear fissures in units, from oldest to youngest, R1, N1, Rz, Nz, southeastern Washington and adjacent Oregon where N stands for normal and R for reversed approximately 15.5 to 17 million years ago polarity (fig. 7). (McKee and others, 1981; Long and Duncan, 1982). Thick sections of Grande Ronde Basalt WANAPUM BASALT crop out in the canyons of the Grande Ronde and Wenaha Rivers and in many of the region's Flows of the Wanapum Basalt were erupted deeply incised creeks (plate 1), (Ross, 1978). from fissures in southeastern Washington between The formation also crops out extensively in the approximately 14 and 15.5 million years ago Blue Mountains to the north, where uplift has (Watkins and Baksi, 1974; Long and Duncan, exposed it. Steeply dipping Grande Ronde Basalt 1982). In the Grande Ronde River-Blue Moun flows on the flank of the Slide Canyon monocline tains region, Wanapum Basalt flows are generally form the northern limit of the Grande Ronde exposed near the top of deep canyons. 10 Geology of the Grande Ronde Lignite Field
Slide Canyon monocline Grande Ronde lignite field
FIGURE 8. - View from the northwest of the steeply dipping south limb of the Slide Canyon monocline, which forms the northern limit of the Grande Ronde lignite field.
Since individual flows of the Wanapum Saddle Mountains Basalt erupted from fissures in Basalt are identifiable by field, petrographic, and south-central and southeastern Washington and chemical characteristics, the formation has been western Idaho. During this period of waning subdivided into several mappable members ( fig. 7). volcanism, thick sediments accumulated in the All members of Wanapum Basalt, except the Priest developing Troy basin (fig. 9). The quiescence Rapids Member, occur in the Grande Ronde dominated by sediment deposition was punctu River-Blue Mountains region ( Swanson and ated by sporadic, short-lived eruptions. As a others, 1979; 1980). The Grande Ronde and result, flows of the Saddle Mountains Basalt Wanapum Basalts are separated by a thick saprolitic are intercalated with three major sedimentary soil throughout much of the region, which interbeds in the Grande Ronde River-Blue Moun provides an excellent marker horizon and correla tains region. tion tool (Ross, 197 8). Since many of the individual flows of the Saddle Mountains Basalt are petrographically and chemically distinct, the formation has been sub SADDLE MOUNTAINS BASALT divided into ten members (fig. 7), (Swanson and others, 1979). The thickest section of the Saddle During the late stages of Yakima Basalt Mountains Basalt and intercalated sediments is Subgroup volcanism, between approximately 6 found in the northern Troy basin (fig. 9), (Ross, and 14 million years ago (Watkins and Baksi, 1978, 1979). The formation thins toward basin 1974; McKee and others, 1977), flows of the margms. Stratigraphy of the Grande Ronde Lignite Field 11
X / / / / X / TROY /
PalmerI / I BASIN
Elgin I 1 N • 0 5 10 15 20 25 MILES
FIGURE 9. - Generalized structure map of northeastern Oregon and adjacent Washington.
STRATIGRAPHY OF THE GRANDE RONDE mineralogic variant of the Yakima Basalt," which LIGNITE FIELD was later named the Saddle Mountains Basalt ( Swanson and others, 1979), (fig. 6). Subsequently, The lignite beds in the Grande Ronde River Gibson (1969) described a vent complex of feeder Blue Mountains region occur within thick sedi dikes and scoriaceous lava flows near the northeast mentary interbeds between flows of the Saddle end of the Blue Mountains, and suggested correla Mountains Basalt. In the vicinity of the lignite tion of these "Puffer Butte" flows with the field, Saddle Mountains Basalt was first identified Umatilla flow of the Saddle Mountains Basalt by Waters (1961), who described a single flow (fig. 7). Walker (1973) described two additional capping 250 ft (76 m) of sediments on a ridge Saddle Mountains Basalt flows in the area and east of Buford Creek in Wallowa County, Oregon. informally named them the Wenaha and Buford He assigned this flow to his "late textural and flows (fig 7). Walker (1979) later mapped the 12 Geology of the Grande Ronde Lignite Field regional distribution of the Saddle Mountains region with the formal Columbia River Basalt Basalt and intercalated sediments in the Oregon Group stratigraphic nomenclature is given in fig. part of the Grande Ronde lignite field. 7. Utilizing the informal nomenclature previ Detailed mapping of Saddle Mountains Basalt ously proposed by Gibson (1969) and Walker flows in this study has shown that a revision of ( 197 3) and introducing some informal names of Ross' stratigraphic nomenclature is necessary. his own, Ross ( 197 8) studied and mapped the Field evidence indicates that two flows of the Saddle Mountains Basalt and intercalated sedi Buford Member interfinger with two flows of the ments in a portion of the lignite field along the Elephant Mountain Member in the study area. Washington-Oregon border. A correlation of Ross' The author's proposed informal stratigraphy of informal stratigraphy of the Saddle Mountains the Saddle Mountains Basalt in the Washington Basalt in the Grande Ronde River-Blue Mountains State portion of the lignite field is given in fig. 10.
Magnetic MEMBER polarity
BUFORD MEMBER R z Medicine Creek flow 0 j:: 4: ::i: a: 0 T MEMBER (informal} u.
·»n · MENATCHEE CREEK sedimentary interbed z 0 -- j:: BUFORD MEMBER ---- cl: T ::i: (/) Mountain View flow a: z 0 u. z~ :::> 0 N ::i: Tule Lake flow (!) . a: :::> w GROUSE CREEK a> ..J (/) 0 sedimentary interbed z 0 w ~ ..J ..J (/) t------+------1--- w UMATILLA MEMBER Sillusi flow N Umatilla flow ~--~------~--~--- SQUAW CANYON sedimentary interbed
FIGURE 10. - Proposed stratigraphy of the Saddle Mountains Basalt in the Washington State portion of the Grande Ronde lignite field. N is normal magnetic polarity; R, reversed; and T, transitional. Structure 13
STRUCTURE
EVOLUTION OF THE BLUE MOUNTAINS (Waters, 1961; Gibson, 1969; Taubeneck, 1970; PROVINCE Price, 1977); and ( 4) a regional fault system with northwest-southeast, northeast-southwest, The Columbia Plateau was created between and north-sou th trends (Camp, 1976; Reidel, 17 .5 and 6 million years ago by the eruption of 1978; Ross, 1978; Shubat, 1979). scores of basalt flows of the Columbia River Basalt These structural elements of the Blue Moun Group. Concurrent with and subsequent to erup tains province can best be explained by a tectonic tion of the flows, the southeast part of the plateau model (Hooper and Camp, 1981) which includes: was uplifted, tilted, gently folded, and faulted. ( 1) Regional east-west tilting ( Swanson and others, Regional deformation produced four major 197 5); ( 2) a stress regime with an axis of maximum structural elements: ( 1) A regional paleoslope compression in a horizontal north-northwest dipping west away from the eastern margin of the south-southeast direction and an axis of maximum plateau (Bond, 1963; Swanson and others, 197 5); tension in a horizontal east-northeast-west (2) large wavelength folds with east-west trend southwest direction (Ross, 1978); and (3) reacti ing axes (Camp, 1976; Ross, 1978; Swanson vation of the pre-basalt structural grain, consisting and others, 1980); (3) dikes with a remarkably of northwest-southeast, northeast-southwest, and consistent north-northwest-south-southeast trend north-south fractures (Hooper and Camp, 1981).
NORTH SOUTH Crest of Blue Mountains Grande Ronde lignite field ------,,- 6000' Grande Ronde River Canyon 5000'
4000'
3000'
2000'
1000'
Sea Level
8 X VERTICAL EXAGGERATION
0 5 10
MILES
Grande Ronde Basalt ; Lower flows of normal magnetic polaritY, $eddle Mountains Basalt magnetostratigraph ic; unit N 1 Grande Ronde Basalt; Lower flows of reve,sed magnetic polar· Wanapum Basalt ity. magnetostratigraphic unit R 1 Grande Ronde Basalt; Upper flows of normal magnetic polantv, magne1os1rati9raphic unit N lmnaha Basalt 2 Grande Ronde Basah; Uppe, flows of reversed magrietlc polar• Mesozoic and Paleozoic metamorphic rock, ity. magnetostratigraphic unit R 2
FIG URE 11. - Schematic cross section of the Blue Mountains in southeastern Washington. After Swanson and others, 1980. 14 Geology of the Grande Ronde Lignite Field
MALLORY RIDGE
ASOTIN CO. ·-,-...· - ·-·- ·-·-·-·WASHINGTON- ·- ·- ·- ·-·-·- WALLOWA CO. OREGON t N I
0 $ 6 tnJIH
0 2 3 4 S 6 7 8 9 ._ilorneterc
FIGURE 12. - Structure map of the Grande Ronde River-Blue Mountains region. After Ross, 1978. See plate 1 for more precise location of structures.
N SADDLE s BUTTE ANTICLINE JULY TOWN OF TROY, RIDGE SLIDE OREGON ! FAULT CANYON GROUSE J_ - - - -=.-=. -C. -C. T MONOC\LINE FLAT 6000 SYNCLINE ------~------l--- - \ \ \ I- 5000 w \ \ w u. \ \ z 4000 GR z 2 I- SM
4X VERTICAL EXAGERATION
FIGURE 13. - Cross section through the Grande Ronde River-Blue Mountains region. Aft.er Ross, 1978. GR= Grande Ronde Basalt, includes T = Troy flow (informal) W = Wanapum Basalt SM= Saddle Mountains Basalt, with intercalated GC = Grouse Creek sedimentary interbed Faults 15
The tectonic regime was regional in scope and long (29 km) system of four en echelon faults remained essentially unchanged throughout middle trending N. 20° E. and one conjugate fault and late Miocene time. trending N. 40° W. (fig. 14 and plate 1). All faults in the system exhibit vertical dip-slip STRUCTURAL GEOLOGY OF THE movement with downthrown blocks on the northwest side of the en echelon faults. Left GRANDE RONDE RIVER-BLUE MOUNTAINS lateral strike-slip movement has also occurred on REGION the Powatka Ridge and Courtney Creek faults. Only minor offsets have been identified north of The Blue Mountains are a broad anticlinal the Grande Ronde River, suggesting that the arch uplifted during the late Cenozoic. The folded Grande Ronde Fault System dies out in the and faulted arch consists of a core of Paleozoic vicinity of the river. and Mesozoic metamorphic rocks mantled by flows of the Columbia River Basalt Group (fig. 11). All formations of the Columbia River Basalt Group (except the Picture Gorge Basalt) crop out in the Blue Mountains arch, but exposures of the metamorphic core rocks and the lmnaha Basalt are rare. The structural elements present in SADDLE BUTTE the Grande Ronde River-Blue Mountains region are discussed below (Ross, 1978, 1979, 1980). Crooked
FOLDS
In the northeasternmost portion of the arch, _ ytASHINGTON __ OREGON the axis of the Blue Mountains uplift coincides with the axis of the Saddle Butte anticline. This asymmetrical anticline has a broad, flat hinge zone and gently dipping limbs (figs. 12 and 13). The north limb dips 2° to 3° and the south limb dips up to 9°, but the south limb of the anticline abruptly steepens and becomes the Slide Canyon monocline (figs. 12 and 13). Monoclinal dips reach a maximum of 49°, although 25° to 30° dips are more common. To the south, the steeply dipping monocline abruptly flattens and merges with the north limb of the Grouse Flat syncline, a structure with very gently dipping limbs (3° to 6°) i and a broad, flat hinge zone (figs. 12 and 13). N Maximum structural relief on the Saddle Butte ~ anticline-Grouse Flat syncline complex is approx 0 2 MILES imately 2,800 ft (850 m). 0._.__. 1 2 KILOMETERS
FAULTS
Most of the prominent faults in the Grande FIGURE 14. - Map of the Grande Ronde Fault System. Ronde River-Blue Mountains region are assigned Ball and bar on downthrown side of to the Grande Ronde Fault System, an 18-mile- faults. After Ross, 1978. 16 Geology of the Grande Ronde Lignite Field
AGE OF TECTONISM the Troy basin documents continued structural deformation during Saddle Mountains time (Ross, 1978). The geographic distribution and thickness Although the age of strike-slip movement of variation of Grande Ronde Basalt magnetostrati the Grande Ronde Fault System has not been graphic units indicate that folding in the Grande accurately determined, it is known that strike-slip Ronde River-Blue Mountains region probably faulting in the region initiated sometime between initiated in late Grande Ronde time (Ross, 1978; eruptions of the Umatilla and Elephant Mountain Camp and Hooper, 1981; Hooper and Camp, Members of the Saddle Mountains Basalt ( Swanson 1981). Development of the Troy basin did not and Wright, 1983), and that it preceded dip-slip begin until late Wanapum time (Swanson and movement ( Ross, 197 8). Equal vertical displace Wright, 1983). The presence of sedimentary ment of flows of the Grande Ronde, Wanapum, interbeds between thick flows of Saddle Moun and Saddle Mountains Basalts indicate that dip tains Basalt, and the restriction of the Saddle slip movement of the Grande Ronde Fault System Mountains Basalt and intercalated sediments to is post-Elephant Mountain in age (Ross, 1978).
GEOLOGY OF THE WASHINGTON STATE PORTION OF THE GRANDE RONDE LIGNITE FIELD
DESCRIPTION OF STRATIGRAPHIC UNITS of oxidized flow tops were not available, polarity measurements were made at the base of the BASALT FLOWS flows. Since overprint of reversed polarity flows by the present-day normal magnetic field is Flows of Saddle Mountains Basalt in the common (Watkins and Baksi, 1974), and unstable Grande Ronde lignite field have diverse field, magnetic components are not removed before petrographic, and chemical characteristics. Detailed field measurements, the reported magnetic polari descriptions of the flows, which follow, include ties should be considered tentative. discussion of the following properties: Petrography. - Includes discussion of the Field characteristics. - Include stratigraphic mineralogy and texture of each basalt flow. position, thickness, hand specimen appearance, weathering characteristics, flow structures Uoint ing and flowtop characteristics), and magnetic Chemistry. - Major element compositions of polarity. The remanent magnetic polarity (nor the flows were determined by the X-ray fluores mal, reversed, or transitional) of each of the ba cence method in the Basalt Research Laboratory salt flows in the study area was determined in at Washington State University. Samples were the field using a Model 70 (Calex Mfg. Co., Inc.) analyzed for oxides of Si, Al, Ti, Fe, Mn, Ca, fluxgate magnetometer. Measurements were Mg, K, Na, and P (Appendix B). Analyses were made on oriented samples, following the pro plotted on six variation diagrams and polygonal cedure of Doell and Cox (1962; 1967). Four or fields were drawn around chemical types (Appen five samples were taken at each outcrop. Where dix B). All flows of Saddle Mountains Basalt in possible, the samples were taken from the oxi the Grande Ronde lignite field belong to one of dized tops of the flows, since the quickly chilled three chemical types ( Umatilla, Elephant Moun portions of flows have proven to give the most tain, or Buford) defined by previous workers reliable readings (Hooper, 1981). When outcrops (Walker, 1973;Wrightandothers, 1973). Basalt Flows 17
UMATILLA MEMBER Canyon sedimentary interbed throughout much of the study area, but where the sediments are The Umatilla Member consists of two flows absent, it overlies flows of the Wanapum Basalt in the Washington State portion of the Grande (figs. 7 and 10). The Umatilla Member is overlain Ronde lignite field. The flows are named, from by the Grouse Creek sedimentary interbed through older to younger, the Umatilla and Sillusi flows, out the Grande Ronde lignite field. Maximum to conform to the stratigraphic nomenclature of thickness of each Umatilla Member flow in the Umatilla Member established by Laval (1956) the lignite field is approximately 200 ft ( 60 m), and formalized by Swanson and others, 1979). (Ross, 197 8). This nomenclature supersedes the myriad of informal names previously assigned to flows of FIELD CHARACTERISTICS the Umatilla Member in the Grande Ronde River Blue Mountains region (fig. 7). To clarify the Fresh basalt of the Umatilla flow is dark confusion, the following correlations are herein blue-black, fine to medium grained, and equi established: granular. It weathers to an orange-brown color. Sillusi flow = Puffer Butte flow of Gibson The flow is best exposed in the cliffs along Bear (1969); Umatilla flow of Ross (1978) Creek (plate 1), where it consists of a thick basal Umatilla flow = Bear Creek flow of Ross colonnade with moderately well-formed vertical (1978); Sopher Ridge flow of Hooper columns, an upper zone characterized by blocky (1981) joints, and a thin, vesicular flow top. The Umatilla The Umatilla Member overlies the Squaw flow has a normal magnetic polarity (Ross, 1978).
Grouse Creek sedimentary interbed
Scale T 200 feet (60 meters) 1
FIGURE 15. - The Sillusi flow in Grouse Creek (sec. 15, T. 6 N ., R. 43 E). Gentle slopes of the flow's scoriaceous top overlie steeper slopes of the basal colonnade. The flow is overlain by the Grouse Creek sedimentary interbed. 18 Geology of the Grande Ronde Lignite Field
Fresh basalt of the Sillusi fl.ow is dark gray and fine grained throughout its thickness. Micro and extremely fine grained, with abundant phenocrysts of plagioclase and clinopyroxene are plagioclase microphenocrysts (up to 2.0 mm long) rare. Intergranular texture is best developed in in an aphanitic groundmass. It weathers to a pale the more crystalline portions of the flow contain yellow-brown or pale orange-brown color. The ing less than 25 percent glass. Intersertal texture flow commonly displays a basal colonnade of is dominant in about the upper 10 percent of the moderately well-formed vertical columns, a middle flow containing over 25 percent glass plus opaques. vesicular zone, and a thick, scoriaceous flow top Subophitic texture is rare. characterized by pale brownish-yellow weathering The Sillusi flow is microporphyritic with and siderite and goethite-filled vesicles. In canyon plagioclase slightly more abundant than clino exposures, the scoriaceous flow top often forms pyroxene (fig. 16). The microphenocrysts are gentle slopes overlying steeper slopes of the basal mostly isolated, but a few occur in rnicroglomero colonnade (fig. 15). The Sillusi flow has a normal porphyritic clusters. Groundmass is intersertal magnetic polarity (Ross, 1978), (this report). with interstices filled with glass, mineraloid, and sometimes carbonate. lntersertal texture occurs PETROGRAPHY in samples containing 20 percent to 50 percent (after Ross, 1978) glass while more crystalline samples (glass less than 20 percent) are intergranular. The glassy The Umatilla flow is essentially equigranular ( over 50 percent glass) vesicular to scoriaceous
black opaques (probably magnetite)
FIGURE 16. - Photomicrograph illustrating the microporphyritic texture of the Sillusi flow. Sample GRB-10. Plane light. 50 X. Basalt Flows 19
upper portion of the flow exhibits hyaloophitic ELEPHANT MOUNTAIN MEMBER texture. Lens-shaped vesicles up to 18.0 X 4.5 mm are present in thin sections from the vesicular In the Washington State portion of the to scoriaceous portions of the flow. Most of the Grande Ronde lignite field, the Elephant Mountain vesicles are lined with goethite. Member consists of two flows, the Tule Lake and Whitetail Butte flows (fig. 10 and plate 1): CHEMISTRY TULELAKEFLOW(NEW) Umatilla Member flows are distinguished from other flows in the Grande Ronde lignite The Tule Lake flow is informally named field by their higher P205 and K20 and lower herein for cliff outcrops on the west side of Tule CaO and MgO contents (Appendix B). The two Lake, in the EY2NWY
Scale
425I feet ( 130 meters) 1
FIGURE 17. - Proposed type locality of the Tole Lake flow (Elephant Mountain Member) in E1hNW1A sec. 9, T. 6 N., R. 43 E. The flow forms the base of the prominent cliff at the back of a narrow bench eroded into the Grouse Creek sedimentary interbed. 20 Geology of the Grande Ronde Lignite Field
Member) in the eastern portion (plate 1). The canyons eroded into the Menatchee Creek sedi Tule Lake flow is approximately 150 ft (45 m) mentary interbed and the Tule Lake (Elephant thick. Mountain Member) and Mountain View (Buford Member) flows ( figs. 19 and 20) . The Whitetail Butte flow is overlain by the Medicine Creek flow WHITETAIL BUTTE FLOW (NEW} (Buford Member) throughout the study area, except where the Medicine Creek flow has been The Whitetail Butte flow is informally named removed by erosion (plate 1). Since the Whitetail herein for outcrops on the 3,536-ft summit of Butte flow is a sheet flow in the western third of Whitetail Butte, in the NW%NW% sec. 31, T. 7 N., the study area, and an intracanyon flow in the R. 44 E. ( fig. 18). At this locality, the Whitetail eastern pare, the thickness of the flow is highly Butte flow overlies the Menatchee Creek sedimen variable. On Grouse Flat, the sheet flow is tary interbed (plate 1). On the south side of approximately 250 ft (7 5 m) thick. Remnants of Grouse Flat, it overlies the Tule Lake flow. In the intracanyon flow are greater than 400 ft (120 other localities, the Whitetail Butte flow fills m) thick.
Mountain View flow
Scale T 250 feet (75 meters) 1
FIGURE 18. - Proposed type locality of the Whitetail Butte flow (Elephant Mountain Member) on the summit of White tail Butte in NWlf.iNWlf.i sec. 31, T. 7 N., R. 44 E. Basalt Flows 21
Mena1chee Creek sedimentary interbed White~il Butte flow (on White~il Butte)
Scale T 400 feet ( 120 meters) J_
FIGURE 19. - The Whitetail Butte flow (Elephant Mountain Member) fills an erosional channel cut into the Menatchee Creek sedimentary interbed and the Mountain View flow (Buford Member) on the east side of "The Bench" in the W1hsec. 30, T. 7 N., R. 44 E.
FIELD CHARACTERISTICS transitional magnetic polarity while the Tule Lake flow has a normal magnetic polarity. The Tule Lake flow generally consists of a basal colonnade of crudely formed vertical PETROGRAPHY columns and a thin, vesicular flow top. Fresh (after Ross, 1978) outcrops of Tule Lake basalt are fine to medium grained, and equigranular. It weathers to a red The two flows of the Elephant Mountain brown color. Member cannot be differentiated in thin section. The most distinctive field characteristic of Basalt of both flows is equigranular, with scattered the Whitetail Butte flow is its complex, chaotic rnicrophenocrysts of plagioclase, clinopyroxene, jointing. Most outcrops of the flow are character and more rarely, opaques (fig. 22). Textures in ized by intricate, elaborate joint patterns produced the flows vary, dependent upon glass plus opaques by the abrupt lateral and vertical change of hori content, as follows: intergranular if less than 25 zontal and vertical columnar joints into blocky, percent, intersertal if 25 percent to 40 percent, platy, or fan joints (fig. 21). Fresh exposures of and hyaloophitic if over 40 percent. Intersertal Whitetail Butte basalt are black, fine to medium to intergranular, or more commonly, intersertal grained, and equigranular. It weathers to a red to hyaloophitic textures occur within a single thin brown color. The Whitetail Butte flow cannot be section. Ophitic and subophitic textures are best distinguished from the Tule Lake flow in hand developed in the flow interiors, where clinopyrox specimen, but the Whitetail Butte flow has a enes attain their broadest dimensions and more 22 Geology of the Grande Ronde Lignite Field
Canyon fill of Menatchee Creek Whitetail Butte flow Medicine Creek flow
Scale T 400 feet (120 meters) _L
FIGURE 20. - View of the cliffs at the head of Grouse Creek (SW1/.i sec. 3, T. 6 N., R. 43 E.}, where the Whitetail Butte flow {Elephant Mountain Member) fills a canyon eroded into the Menatchee Creek sedimentary interbed and the Tule Lake flow {Elephant Mountain Member). readily enclose plagioclase groundmass grains. No Elephant Mountain Member are distinguished distinct flow banding is developed and vesic1es are from flows of the Umatilla and Buford Members near1y all circular in cross section. The vesicles by their higher Ti02 and lower Si02 contents generally are completely filled with mineraloids (Ross, 1978) (Appendix B of this report). or carbonate. In cross section, many vesicles are Six samples of Whitetail Butte basalt are rimmed with small, 1ath-shaped grains of plagio anomalously high in Si02 and Ti02 and low in clase arranged end-to-end, tangentially around FeO and MgO (Appendix B). All of these samples the edge of individual vesicles. are from portions of the Whitetail Butte flow which invaded sediments of the Menatchee Creek CHEMISTRY in terbed (discussed later).
Major element chemistries of the Tule Lake RADIOMET RIC AGE DATES and Whitetail Butte flows (Appendix B) are very similar to each other and to the Elephant Mountain One sample of each flow of the Elephant chemical type defined by Wright and others Mountain Member was collected during this (1973). For this reason, it is assumed that the investigation and sent to Geochron Laboratories flows are correlative with the Elephant Mountain (Kreuger Enterprises, Inc.) for potassium-argon Member in the central Columbia Plateau (Swanson age dating. The samples were fresh, holocrys and others, 1979). In the study area, flows of the talline, nonvesicular, and nonamygdaloidal basalt. Basalt Flows 23
FIGURE 21. - Complex, chaotic jointing of the Whitetail Butte flow (Elephant Mountain Member) is exposed in the cliff at the head of Grouse Creek (SW1/.1SW1/.s sec. 3, T. 6 N., R. 43 E.).
Before sending the samples to the Geochron SAMPLE WI2 Laboratory, they were pretreated as follows, in Tule Lake flow 9.4 ± 0.7 m.y.b.p. the Division of Geology and Earth Resources From outcrop of 3-foot-diameter vertical columns laboratory, to remove nonradiogenic argon at 3,110 ft in the NEY.iSEY.iSEY.i sec. 4, T. 6 N., trapped mechanically in the lattice structure of R. 43E. clay minerals: 1. Sample crushed to 80 mesh SAMPLE Wll2 2. Sample sieved and washed with water Whitetail Butte flow 10.7 ± 0.8 m.y.b.p. 3. Sample washed in 14 percent HN03 for 30 minutes From outcrop of 4-foot-diameter vertical columns 4. Sample washed in 5 percent HF for 1 at 3,280 ft in the NEY.iNWY.iSWY
ilmenite clinopyroxene
glass
FIGURE 22. - Photomicrograph illustrating the equigranular texture of the Whitetail Butte flow (Elephant Mountain Member). Sample GRB-34. Plane light. 50 X.
BUFORD MEMBER by the Menatchee Creek sedimentary interbed throughout most of the study area. In the In the Washington State portion of the vicinity of the type locality, the Mountain View Grande Ronde lignite field, the Buford Member flow averages 250 ft (75 m) thick. consists of two flows, the Mountain View and Medicine Creek flows (fig. 10 and plate 1). MEDICINE CREEK FLOW (NEW)
MOUNTAIN VIEW FLOW (NEW) The Medicine Creek flow is informally named herein for cliff outcrops on the southwest The Mountain View flow is informally side of Medicine Creek in the W!hNWY.i sec. 30, named herein for cliff outcrops in the EYi sec. 36, T. 7 N., R. 44 E. (fig. 24 ). Throughout the study T. 7 N., R. 43 E., one mile west of Mountain area, the Medicine Creek flow overlies either the View (fig. 23). In the eastern half of the study Whitetail Butte flow (Elephant Mountain Member) area, the flow conformably overlies the Grouse or the Menatchee Creek sedimentary interbed Creek sedimentary interbed, and in the west (plate 1). The Medicine Creek flow is the young half it fills a canyon eroded into the Tule Lake est Columbia River Basalt Group flow present in flow (Elephant Mountain Member). It is overlain the Washington State portion of the lignite field. Basalt Flows 25
Whitetail Butte flow (on Whitetail Buttel Scale T 750 feet ( 230 meters) l
FIGURE 23. - View across Menatchee Creek to the proposed type localities of the Mountain View flow (Buford Member) and Menatchee Creek sedimentary interbed on the south end of "The Bench" (sec. 36, T. 7 N., R. 43 E.). The Menatchee Creek and Grouse Creek sedimentary interbeds crop out on topographic benches between flows of Saddle Mountains Basalt.
Outcrops north of Swank Springs (SW~ sec. 20, displays a basal colonnade of crudely formed T. 7 N., R. 44 E.) indicate that the original vertical columns, which are broken into large thickness of the Medicine Creek flow was approx blocks by widely spaced horizontal joints. A imately 160 ft (50 m) in the study area. Else thick vesicular zone separates the basal colonnade where, much of the flow has been removed by from the flaw's scoriaceous top. The Medicine erosion, and flow thickness cannot be determined. Creek flow has a reversed magnetic polarity (Ross, 1978; Swanson and others, 1980). The Mountain View flow cannot be dis FIELD CHARACTERISTICS tinguished from the Medicine Creek flow in hand specimen. The basalts are black, fine grained, and The Mountain View flow consists of a basal plagioclase-phyric when fresh, but all natural colonnade of moderately well-formed vertical outcrops of both flows are deeply weathered. columns and an overlying vesicular zone which The weathered basalt is characterized by trans grades into a scoriaceous flow top. Vesicles are lucent to chalky white feldspar phenocrysts commonly filled with botryoidal goethite. The surrounded by a weathered light-gray groundmass, Mountain View flow has a transitional magnetic which is "peppered" by abundant minute black polarity. opaque grains. Weathering rinds are a pale The lower half of the Medicine Creek flow orange-brown color. 26 Geology of the Grande Ronde Lignite Field
Whitetail Butte flow Medicine Creek flow Scale
250I feet (75 meters) 1
FIGURE 24. - Proposed type locality of the Medicine Creek flow (Buford Member) in the W1hNWV.. sec. 30, T. 7 N., R. 44 E. View west to the east side of "The Bench" shows the Medicine Creek flow overlying the Whitetail Butte flow (Elephant Mountain Member).
PETROGRAPHY very similar to each other and to the Buford (after Ross, 1978) chemical type defined by Walker (1973). For this reason, the flows are assigned to the Buford Both flows of the Buford Member are micro Member. In the study area, £lows of the Buford porphyritic ( fig. 2 5), with their groundmass Member are distinguished from flows of the textures grading from intergranular to intersercal Umatilla and Elephant Mountain Members by to hyaloophitic as the glass content increases their lower P20 5, Ti02, and total Fe contents toward the top of the flows. Ophitic and sub (Ross, 1978; Appendix B of this report). ophitic textures are well developed, especially in the intergranular portions of the flows. Micro SEDIMENTARYINTERBEDS phenocrysts commonly form microglomero porphyritic clots. Scattered plagioclase pheno In the Washington State portion of the crysts and rare clinopyroxene phenocrysts are Grande Ronde lignite field, three sedimentary present. interbeds are intercalated with flows of the Saddle Mountains Basalt (fig. 10). Only the upper CHEMISTRY two, the Grouse Creek and Menatchee Creek interbeds, were mapped in this investigation. In Major element chemistries of the Mountain the study area, these two interbeds are indistin View and Medicine Creek flows (Appendix B) are guishable, except by stratigraphic position. Sedimentary Interbeds 27
clinopyroxene
I glass black opaques (probably magnetite) FIGURE 25. - Photomicrograph illustrating the microporphyritic texture of the Mountain View flow (Buford Member). Sample GRB-19. Plane light. 50 X.
GROUSE CREEK SEDIMENTARY INTERBED underlies the Whitetail Butte and Medicine Creek flows. It reaches a maximum thickness of 200 ft The Grouse Creek interbed (Ross, 1978) ( 61 m) in the vicinity of the type locality. overlies flows of the Umatilla Member and under lies the Tule Lake and Mountain View flows INTERBED CONSTITUENTS (fig. 10 and plate 1). The interbed varies in thick ness from less than 50 ft (15 m) on the southwest Sediments are poorly exposed in the study side of the study area to 250 ft (7 5 m) along the area. Outcrops are limited to scattered roadcuts, axis of the Grouse Flat syncline. streamcuts, and borrow pits, which expose sub arkosic sandstone and siltstone, diatomite, MENATCHEE CREEK carbonaceous shale, lignite, massive siltstone and SEDIMENTARYINTERBED(NEW) claystone, and hyaloclastite. Microscopic examination of the subarkosic The Menatchee Creek interbed is informally sandstones and X-ray diffraction analyses of the named herein for outcrops on a narrow bench < 2 micron fraction of the su barkosic sandstones below Whitetail Butte (fig. 23), lYi miles (2.4 km) and siltstones, indicate they are composed pre east of Menatchee Creek (WYiNWY.t sec. 31, dominantly of quartz, with variable amounts of T . 7 N., R. 44 E.). The interbed overlies the feldspar, muscovite and biotite mica, hornblende, T ule Lake and Mountain View flows (fig. 10), and and kaolinite. Subarkosic sandstone, the most 28 Geology of the Grande Ronde Lignite Field common lithology in the sedimentary interbeds, SOURCE OF INTERBED SEDIMENTS is very fine to coarse grained (Appendix C), poorly to moderately well sorted, friable to Two size fractions (80 mesh and 120 mesh) moderately indurated, and locally cross bedded. of five samples of subarkosic sandstone from the It contains sparse fragments of basalt, quartzite, Grouse Creek and Menatchee Creek interbeds and crystalline rocks. Individual mineral grains were analyzed to determine their heavy mineral and rock fragments in the sandstone are sub compos1t10ns. The principal heavy minerals rounded to subangular. The combination of present in both fractions of all samples are positive skewness and high sorting values calcu garnet (almandite or spessartite), epidote, and lated from the grain size distribution curves in black opaques (magnetite and ilmenite). Horn Appendix C suggest that the sandstones were blende is abundant in one sample but sparse in deposited in a fluvial environment (Friedman, the others; trace amounts of actinolite, sphene, 1967). rutile, and zircon are also present. This heavy Diatomite in the study area is white when mineral assemblage is characteristic of granitic pure, but it commonly grades into black, quartz and contact metamorphic rocks. rich carbonaceous shale (Appendix D). The car The source area(s) for the sandstones in the bonaceous shale often grades into lignite. interbeds could have been either the Wallowa X-ray diffraction analyses of the massive Mountains of Oregon or the Rocky Mountains of siltstone and claystone (Appendix D) indicate western Idaho (or both) (fig. 9). The northern that their primary constituent is kaolinite; they Wallowa Mountains are a complex assemblage of also contain abundant fragments of dark-brown Paleozoic and Mesozoic limestones, shales, organic debris. The origin of the siltstone and sandstones, and greenstones intruded by Creta claystone is uncertain; they may represent either ceous granodiorite of the Wallowa batholith (Ross, in situ weathering of feldspar-rich sediments or 1938; Smith and Allen, 1941). Epidote and deposition of detrital kaolinite. garnet are the major constituents of tactites Hyaloclastite is a glassy sand formed by the found there. Tactites are rocks formed by the phreatic brecciation of basaltic lava as it suddenly contact metamorphism of limestone. Hornblende chilled upon contact with water (McDonald, is a principal constituent and magnetite and 1972). It is composed of thousands of minute sphene are prominent accessory minerals in the plates of basaltic glass which are often altered to Wallowa batholith granodiorite. Mesozoic shales, palagonite. limestones, and dolomites intruded by Cretaceous The Menatchee Creek interbed does contain granitic batholiths crop out in the Rocky Moun one distinctive lithologic horizon which is ap tains of western Idaho as well (Bond and others, parently not present in the Grouse Creek interbed. 1978). They are composed of similar mineral At two widely separated outcrops*, subarkosic constituents. sandstone beds at the base of the Menatchee Creek From their source area(s), the detrital interbed are composed of approximately 5 to 10 sediments were swept into the Troy basin and percent glass shards. The glass is dark brown, deposited with tuffaceous sediments derived from fresh, angular, and vesicular and has a refractive pyroclastic eruptions outside of the basin and index of 1.498, indicative of a volcanic glass of with diatomite, carbonaceous shale, and peat of rhyolitic composition (Williams and others, 1954). intrabasin origin. It must be a product of explosive volcanism from outside of the study area. GRANDE RONDE LIGNITES
DISTRIBUTION AND THICKNESS • Roadcut at 3,220 ft elevation in the NWY.SEY..SEY. sec. 4, T. 6 N., R. 43 E.; roadcut at 3,290 ft elevation in the NEY.SWY. Lignite is very poorly exposed in the Grande NWY. sec. 30, T. 7 N., R.44 E. Ronde lignite field, but limited outcrops are Grande Ronde Lign ites 29
found in springs, creeks, and roadcuts. Four ploration holes drilled by private energy compa exposures of lignite in the Grouse Creek interbed nies show that the lignite in the Grouse Creek are known: interbed underlies most of the study area and 1. Mountain View mine: SWl,4SWl,4SW!l.i reaches a maximum thickness of 40 ft (12 m). sec. 31, T. 7 N., R. 44 E. This thick lignite bed lies at or near the base of 2. McLoughlin Spring: NE!i.iNE!i.iSE!-4 sec. the Grouse Creek interbed, just above the contact 29, T. 7 N., R. 44 E. between the sediments and the underlying Umatilla 3. Medicine Creek: SE!l.iSWY.iNE!l.i sec. 30, Member flows. Springs commonly emerge where T. 7 N., R. 44 E. the lignite crops out ( fig. 26). 4. Sheep Creek: NW!l.iNE!l.iNWY.i sec. 22, Lignite beds in the Menatchee Creek interbed T. 6 N., R. 43 E. crop out at only two localities: Of these localities, lignite thickness is known 1. East Grouse Flat: NEY.iNE!i.iSEY.i sec. 3, only from the abandoned Mountain View mine, T. 6 N., R. 43 E. where a 300-ft-long adit was driven to expose 2. Grouse Creek: SEY.iSWY.iNE!-4 sec. 4, lignite more than 27 ft ( 8 m) thick (Washington T. 6 N., R. 43 E. Division of Geology and Earth Resources un The lignite is very poorly exposed at both of published data), and from McLaughlin Spring, these localities. Thickness and distribution of where an excavation exposed lignite more than lignite beds in the Menatchee Creek interbed are 16 ft (5 m) thick (Russell, 1901). Logs of ex- poorly known.
FIGURE 26. - View north to McLoughlin Spring and two other unnamed springs on a narrow bench eroded into the Grouse Creek sedimentary interbed. Springs commonly emerge where lignite crops out, just above the contact between the Umatilla Member and the Grouse Creek interbed. 30 Geology of the Grande Ronde Lignite Field
QUALITY DEPOSITIONAL ENVIRONMENT
Analyses of four lignite samples from Outcrop and borehole data indicate that scattered localities in the Grande Ronde lignite accumulation of the thick peat at the base of the field are given in table 1. Samples nos. 1, 2, and 3 Grouse Creek interbed (later converted to lignite) were collected from highly weathered outcrops in was preceded only by the deposition of diatomite the study area. Sample no. 4 was collected from and(or) carbonaceous shale. This implies that the a fresh roadcut southeast of the study area. peat was deposited in bog lakes which formed on All samples were analyzed by the U.S. the surface of the Umatilla Member. Formation Department of Energy except sample no. 1, of these lakes was closely related to the initiation which was analyzed by the U.S. Bureau of Mines. of the Blue Mountains uplift and the development The lignites have a maximum Btu/lb value of of the Troy basin (see next section). 7,944 (as received) and a maximum fixed carbon The depositional environment of the lignite value of 39.6 percent (as received). Sulfur con in the Menatchee Creek interbed cannot be de tent is less than 0.5 percent in all four samples, termined from the limited outcrops available for while ash content ranges from 5.7 to 16.7 percent study. (as received).
TABLE 1. - Analyses ofGrande Ronde lignites
AR - as received MF - moisture free MAF. moisture and ash free
l - 2 3 4 Moisture (AR) 15.8 36.8 33.4 12.5 t,l Volatile matter (AR) 31.8 24.0 35.0 43.9 f-, ~ Volatile matter (MF) <<1> 37.8 37.9 52.5 50.2 :!l:,.. Volatile matter (MAF) 44.6 51.5 57.4 60.9 -~ Fixed carbon (AR) 39.6 22.5 25.9 28.2 ozX< Fixed carbon (MF) 47.0 35.6 38.9 32.l g: < Fixed carbon (MAF) 55.4 48.5 42.6 39.l Ash (AR) 12.8 16.7 5.7 15.4 Ash (MF) 15.2 26.5 8.6 17.7
Hydrogen (AR) 4.4 6.0 7.0 5.4 Hydrogen (MF) 3.1 3.1 4.9 4.6 Hydrogen (MAF) 3.7 4.2 5.3 5.5
.a ::::. BTU (AR) 7,815 5,027 6,697 7,944 :I BTU (MF) 9,263 7,949 10,053 9,078 ~ BTU(MAF) 10,953 10,809 10,998 11,024 1 (OGER No. 5-76) SW14NE14 sec. 30, T. 7 N., R. 44 E. • Medicine Creek 2 (OGER No. 8·77) SW14NE14 sec. 30, T. 7 N .. R. 44 E. • Medicine Creek 3 (OGER No. 9-77) NE14SE14sec. 29, T. 7 N., R. 44 E.· McLoughlin Spring 4 (OGER No. 11·80) NE14NE14 sec. 35, T. 6 N ., R. 44 E. - Buford Creek, Oregon Sediment Deposition 31 DISCUSSION OF COMPLEX STRATIGRAPHIC was controlled by the two conditions discussed RELATIONSHIPS below. Saddle Mountains Basalt time in the Grande DEVELOPMENT OF THE TROY BASIN Ronde lignite field was dominated by the tectonic evolution of the Blue Mountains and Troy basin, Sediments of the Grouse Creek and Men the accumulation of sediments and peat, and the atchee Creek interbeds were deposited in the sporadic eruption of basalt flows. The synchro Troy basin, a structural depression which formed neity of these events produced complex strati south and east of the Blue Mountains uplift graphic relationships between flows and sediments (fig. 9). The tectonic evolution of this basin (plate 1) that must be understood before lignite controlled epiclastic sediment deposition and, reserves can be accurately estimated. more importantly, peat accumulation. In early Saddle Mountains Basalt time, two SEDIMENT DEPOSITION flows of the Umatilla Member erupted from vents near the Washington-Oregon border and flowed Sediment deposition in the Grande Ronde west down a broad river valley to the central lignite field during Saddle Mountains Basalt time Columbia Plateau ( fig. 27 ). Shortly after eruption Rlver / Lewiston \ \ \ \ BLUE MOUNTAINS i '\ \ -c- Puffer / v, ,vButte · i ~ l:v '\ .J ~/ ROCKY WASHINGTON /.• ' ~ •.:' "<" .:;.::r'-~ ..;· - - . - . - . - . - . - . - . - . - . -4- ?~ -~-~:--'-. I _.,,.. OREGON · - ·-\ MOUNTAINS .----·-·-· \~" \ FIGURE 27. - Probable drainage pattern (dark black arrows) in the Grande Ronde River-Blue Mountains region during early Saddle Mountains Basalt time. Umatilla Member flows erupted from vents near Puffer Butte and Troy, Oregon, and flowed west to the central Columbia Plateau. Present locations of the Columbia, Snake, Clearwater, and Grande Ronde Rivers shown for reference only. 32 Geology of the Grande Ronde Lignite Field of these flows, uplift of the Blue Mountains Ronde River valley to the present-day site of blocked the westward flow of this river ( Swanson Lewiston, Idaho, where they turned west and and Wright, 1983), causing bog lakes to form and flowed to the central Columbia Plateau (fig. 29). peat to accumulate throughout the Troy basin The thickest sediments in the Grouse Creek ( fig. 28). As uplift of the Blue Mountains to the and Menatchee Creek interbeds occur near the north and west continued, a northeasterly dipping center of the Troy basin; sediment thickness paleoslope developed and a new river system decreases toward basin margins. However, well began to form (fig. 29). Once this river system logs indicate that the interbeds in the study area became established, the lakes and bogs in the do not thin substantially toward the Slide Canyon Troy basin were drained, peat accumulation monocline to the north. This implies that the ended, and deposition of Grouse Creek interbed northern limit of the depositional basin was once epiclastic sediments began. Soon after, flows of farther north than the present site of the hinge the Elephant Mountain Member erupted and zone between the Slide Canyon monocline and flowed northeastward down this ancestral Grande the Grouse Flat syncline (figs. 12 and 13). :E ! ::I:,O~1- G')z1l> :I: -1.0 ~I River l ROCKY ___ .,.,,-,,,· ,/ MOUNTAINS ·-·--· \ \.""'-9,."'... ~ t MILES N '-·, 0 5 10 15 20 25 \ 0 5 iO 15 20 26 \ K ILOMETERS \ / • I ~i <,;.0i.f o~lo"' . .... I WALLOWA I I MOUNTAINS j I FIGURE 28. - Probable drainage pattern (dark black arrows) in the Grande Ronde River-Blue Mountains region during accumulation of the thick peat (now lignite} at the base of the Grouse Creek sedimentary interbed. Bog lakes occupied the poorly drained Troy basin at this time. Present locations of the Columbia, Snake, Clearwater, and Grande Ronde Rivers shown for reference only. Sediment Deposition 33 :1: · River :z:'o~'- z-1)> :z: c,.o diz, I Riv~r ROCKY \ ·- · - · -·-\ .,...../ '-..~ ----·-· \ \ ·1.....""-9,." t MILES ·~ N 0 S 10 15 20 25 \ 0 6 10 15 20 25 \ K ILOMETERS \ I • / ~· ,9/o'-'. :t: o//t/Q"' .... WALLOWA I I MOUNTAINS I I FIGURE 29. - Probable drainage pattern (dark black arrows) in the Grande Ronde River-Blue Mountains region during middle Saddle Mountains Basalt time. Elephant Mountain Member flows erupted from vents near Troy, Oregon, and flowed northeast down an ancestral Grande Ronde River valley to the Lewiston basin then west to the central Columbia Plateau. Present locations of the Columbia, Snake, Clearwater, and Grande Ronde Rivers shown for reference only. FLOW SURFACE TOPOGRAPHY relationships suggest that the vent for the Umatilla flow (Umatilla Member) may have been located in Topographic relief on the surfaces of the the vicinity of Bear Creek, just northeast of Troy, Saddle Mountains Basalt flows in the Grande Oregon (plate 1). Ross (1978) identified and Ronde lignite field is often substantial. Field mapped a complex of north- northwest-trending evidence indicates this relief is constructional feeder dikes along the west edge of Grouse flat, topography formed by the building of cinder and which marks the location of the vent for at least spatter cones and low shield volcanoes at the one flow of the Elephant Mountain Member. No vents of some of the Saddle Mountains Basalt vents for the flows of the Buford Member have flows in the lignite field. been positively identified, but since the flows Price (1977) described a lava cone complex were restricted to a relatively small area in the at Puffer Butte, 6 miles northeast of the study vicinity of the Grande Ronde River, the vents for area, and determined it was the vent for the these flows must have also been located there. Sillusi flow (Umatilla Member). Stratigraphic Interbed sediments deposited on flows near 34 Geology of the Grande Ronde Lignite Field topographically high vent areas are significantly ment which was originally deposited. The events thinner than those away from vent areas. The discussed below substantially reduced the volume Grouse Creek interbed thins substantially just of sediments and lignite present in the Grande east of the eastern border of the study area, near Ronde lignite field today. the Sillusi flow (Umatilla Member) vent at Puffer Butte. The Menatchee Creek interbed apparently INVASIVE FLOWS thins significantly and may disappear altogether on the west side of Grouse Flat, near the Elephant Invasive basalt flows, lava flows which Mountain Member vent. Since the thickest lignite burrowed into sediments as they overrode them, deposits in the interbeds of the Grande Ronde have been described at numerous localities on the lignite field occur near the base of the interbeds, Columbia Plateau (Schmincke, 1964). Within topographic highs on the surfaces of the basalt coarse-grained sediments, these flow intrusions flows underlying the interbeds probably prevented generally form sheets, tongues, or globular masses peat .accumulation in some areas. of unfragmented basalt. Invasion of finer-grained sediments formed basalt-sediment breccias known SEDIMENT DESTRUCTION as peperites, intimate mixtures of fragmented basalt and shattered sediments which resulted Several geologic events, which followed the from the hot liquid lava churning up wet, uncon deposition of each of the interbeds in the study solidated sediments ( Schmincke, 1965). Several area, destroyed or displaced much of the sedi- examples of invasive flows are well exposed in invasive flow of the Elephant Mountain Member sediments Scale T 10 feet (3 meters) 1 FIGURE 30. - An invasive flow of the Elephant Mountain Member exposed in a borrow pit on Grouse Flat (NW%NW1/.i SW 1~ sec. 8, T. 6 N., R. 43 E.). The flow invaded diatomite and organic mud (nowcarbonaceousshale). Sediment Destruction 35 borrow pits and roadcuts in the Grande Ronde invaded sediments of the Grouse Creek interbed lignite field: (fig. 71). During invasion, the lava shoved com 1. An excellent three-dimensional exposure petent beds of subarkosic sandstone and siltstone occurs in a borrow pit on Grouse Flat (NW%NW% in to a vertical position. SW% sec. 8, T. 6 N., R. 43 E.), where a flow of 3. A roadcut near Swank Springs (SE%SW% the Elephant Mountain Member intrudes sedi SW% sec. 20, T. 7 N., R. 44 E.) exposes basalt of ments of a thin interbed (fig. 30). At this locality, the Mountain View flow which invaded sediments the lava apparently flowed into a swampy lake of the Grouse Creek interbed. A thin peperite underlain by diatomite and organic debris. Upon marks the contact between the flow and the contact with the water, the lava suddenly chilled sediments. and brecciated, forming a glassy sand (hyaloclastite). Field relationships in the study area (plate 1) As the lava overrode the lake, it stirred up the un indicate that as the Tule Lake and Mountain View consolidated sediments, producing an intimate flows overrode unconsolidated sediments of the mixture of diatomite, organic debris, and hyalo Grouse Creek interbed, the flows invaded the clastite. The lava then burrowed into the sedi sediments. Younger flows which overrode sedi mentary pile, forming a large intrusion from which ments of the Menatchee Creek interbed invaded numerous small dikes emanated. those sediments as well. Evidence for this "bur 2. Outcrops in a borrow pit near Grouse rowing" is abundant on the interbed benches in Creek (SE%NW%NE% sec. 9, T. 6 N., R. 43 E.) the study area, where erosional remnants of invas expose basalt of the Tule Lake flow which has ive structures crop out as small basalt hills sur- FIGURE 31. - Erosional remnants of invasive structures formed at the base of the Mountain View flow crop out as small basalt hills on the Grouse Creek interbed bench near the south end of "The Bench" (sec. 36, T. 7 N ., R. 43 E.). 36 Geology of the Grande Ronde Lignite Field FIGURE 32. - Details of the small basalt hills shown in fig. 31. rounded by sediments (figs. 31 and 32). bed. Small hills adjacent to the spring are com In places, the invasive basalt flows burrowed posed of basalt of the Mountain View flow, which completely through the interbeds and are in direct burrowed through approximately 250 ft (75 m) contact with the underlying basalt flows. Good of Grouse Creek sediments and destroyed some of examples are exposed at the Medicine triangula the lignite bed which crops out at the spring tion station on Hanson Ridge (NE\4SW\4SW\4 sec. (fig. 34). 28, T. 7 N., R. 44 E.) and along an unnamed ridge on the southwest side of Cougar Creek CANYON CUTTING (SE\4NE\4NW\4 sec. 32, T. 7 N., R. 44 E.) where basalt of the Mountain View flow directly over Canyon cutting and the extrusion of basalt lies the scoriaceous flow top of the Sillusi flow flows both accompanied structural deformation (fig. 33). in the Grande Ronde River-Blue Mountains region Invasive basalt flows in the Grande Ronde during Saddle Mountains Basalt time. For this lignite field displaced great volumes of sediment reason, intracanyon flows of Saddle Mountains during the process of invasion. More importantly, age are common in the Grande Ronde lignite where the flows burrowed completely through field (plate 1). the sediments, they destroyed some of the thick In the study area, the best exposure of intra lignite beds near the base of the interbeds. This can yon basalt is located in the cliffs at the head is evident at McLaughlin Spring (NE\4NE\4SE\4 of Grouse Creek (SW\4SW% sec. 3, T. 6 N., sec. 29, T. 7 N., R. 44 E.), where 30 ft (9 m) of R. 43 E.). At that locality, the Whitetail Butte lignite lies at the base of the Grouse Creek inter- flow fills a canyon eroded into the Menatchee Sediment Destruction 37 FIGURE 33. - View southwest to a linear ridge of basalt of the Mountain View flow that overlies the Sillusi flow (SE'/.i NE1/.aNW% sec. 32, T. 7 N., R. 44 E.). At this locality, the Mountain View flow "burrowed" com pletely through the 250-ft-thick Grouse Creek sedimentary interbed. Creek interbed and the Tule Lake flow (figs. 20 Whitetail Butte flow that intruded canyon walls and 65). Another exposure of the Whitetail composed of Menatchee Creek sediments: Butte intracanyon flow crops out on the east side 1. Roadcuts on the east side of "The Bench" of "The Bench" (WYi sec. 30, T. 7 N., R. 44 E.), (SW~NW~ sec. 30, T. 7 N., R. 44 E.), (figs. 58 and 69). where the flow fills a broad can yon eroded into 2. A roadcut at the head of Grouse Creek the Menatchee Creek interbed and the underlying (NW~SE~SE~ sec. 4, T. 6 N., R. 43 E.), (figs. 35 Mountain View flow (fig. 19). Still another and 70). Whitetail Butte flow canyon fill crops out in cliffs The combination of sediment erosion during on the west side of Grouse Creek (Nl/2NW~ sec. 9, canyon cutting and basalt invasion of sediments T. 6 N., R. 43 E.), (figs. 63 and 64). during canyon filling has destroyed a significant volume of sediments in the Grande Ronde lignite Field relationships observed in roadcuts and field. Lignite beds probably have also been streamcuts along Sheep Creek (plate 1) indicate removed by these processes. that at that locality the Mountain View flow occupies a canyon eroded into the Tule Lake flow (fig. 64). The base of the canyon was apparently FOLDING eroded into the Grouse Creek interbed. Where basalt flows filled canyons eroded into interbed sediments, lava often invaded the Following their deposition, the interbeds canyon walls during filling. Outcrops at two and intercalated basalt flows in the study area localities in the study area expose basalt of the were folded during the continued development 38 Geology of the Grande Ronde Lignite Field FIGURE 34. - View of McLoughlin Spring (NE1ANE1ASE 1A sec. 29, T. 7 N., R. 44 E.). Small hill adjacent to spring is composed of basalt of the invasive Mountain View flow. of the Saddle Butte anticline-Grouse Flat syncline interbeds were encountered, the streams eroded complex (figs. 12 and 13). As a result of this laterally, forming benches. As lateral erosion folding, the sedimentary interbeds rise gently occurred, interbed sediments were reworked and, from the Grouse Flat synclinal axis to the southern in places, deposited as fluvial sand and gravel limb of the Slide Canyon monocline, where dips (fig. 36). In some localized areas within the abruptly steepen (fig. 68). North of the hinge Grande Ronde lignite field, large volumes of zone, the interbeds have been eroded from the interbed sediments have apparently been reworked steeply dipping monocline. It is impossible to and redeposited, probably destroying lignite beds determine the volume of sediments eroded from in the process. the monocline, since the original northern limit of During development of the benches, lateral the interbeds is unknown. erosion by rivers and streams undercut the cliffs"" at the back of the benches, triggering landslides. DEVELOPMENT OF BENCHES In places where the cliffs at the back of the benches are partially composed of water-bearing In response to regional uplift following sediments, landslides are still active. Recent land Columbia River Basalt Group volcanism, the slide blocks which slid out onto the benches are Grande Ronde River and its tributaries cut down easy to recognize, but identification of older, through the thick pile of basalt flows and inter partially eroded landslide deposits on the benches calated sediments. When the easily erodable is more difficult. Landslides 1,ave not significantly Sediment Destruction 39 FIGURE 35. - A roadcut at 3,220-ft elevation, in the NW14SE1A sec. 4, T. 6 N., R. 43 E., exposes a dike of the Whitetail Butte flow, which has intruded subarkosic sandstone at the base of the Menatchee Creek sedimentary interbed. The dike is approximately 1 ft (0.3 m) thick and has a thin, glassy selvage. reduced the volume of interbed sediments present excellent example of a recent landslide is located on the benches, but their deposits often cover the on the east side of Grouse Creek (N1h sec. 10, base of the cliffs and the back of the benches. An T. 6 N., R. 43 E.), (plate 1). 40 Geology of the Grande Ronde L ignite F ield r FIGURE 36. - View of a broad bench eroded into the Grouse Creek interbed on the east side of Grouse Creek (center of sec. 10, T. 6 N., R. 43 E.). During the bench-forming erosion some of the interbed sediments were apparently reworked by stream activity and redeposited on the benches as younger fluvial deposits. SUMMARY GEOLOGIC HISTORY organic mud and peat in lakes and bogs and detrital sand, silt, and clay in streams. Collec Structural deformation and sediment deposi tively, these sediments are informally named the tion dominated the late stages of Columbia River Squaw Canyon interbed (Ross, 1978). They Basalt Group volcanism in the Grande Ronde attain a maximum thickness of 50 ft (15 m) in lignite field. During long periods of volcanic the study area. quiescence between approximately 14 and 10 Approximately 13.5 million years ago million years ago, sediments derived from sur (Rockwell Hanford Operations unpublished data) rounding highlands were transported into the the Umatilla flow (Umatilla Member) erupted developing Troy basin where they accumulated from a vent in the western part of the Troy basin with sediments of intrabasin origin. Sediment (Hooper, 1981, personal communication) and deposition was punctuated by sporadic, short flowed west to the central Columbia Plateau. Soon lived eruptions of Saddle Mountains Basalt. after, the Sillusi flow (Umatilla Member) erupted In the Washington State portion of the from a vent in the eastern part of the Troy basin Grande Ronde lignite field, Saddle Mountains (Gibson, 196 9) and also flowed west to the central Basalt time began with the accumulation of plateau (Anderson and others, in preparation). Lignite Reserves and Suggestions for Exploration 41 Uplift of the Blue Mountains soon blocked (Elephant Mountain Member). In the western the westward flow of the river whose valley the part of the study area where sediment erosion was Umatilla Member flows had occupied, apparently apparently more complete ( or the original thick causing lakes and bogs to form throughout much ness of the Menatchee Creek interbed sediments of the Troy basin. Thick peat (later converted to was much less), the Whitetail Butte flow is a lignite) accumulated in these bogs before a new sheet flow. Like the Tule Lake flow, the White drainage system developed. The peat was then tail Butte flow apparently flowed northeastward buried by the influx of epiclastic sediments. down an ancestral Grande Ronde River valley Informally named the Grouse Creek interbed by into the Lewiston basin, then westward to the Ross (1978), the lignite and sediments reach a central Columbia Plateau ( Swanson and others,· maximum thickness of 250 ft (7 5 m) in the study 1979). area. The Medicine Creek flow (Buford Member) Approximately 10 million years ago, the represents the last eruption of the Columbia River Tule Lake flow (Elephant Mountain Member) Basalt Grdu p in the Grande Ronde River region. It erupted from a vent in the Troy basin. As the was apparently restricted to the Troy basin, but flow overrode unconsolidated sediments of the erosion of the flow has made reconstruction of its Grouse Creek interbed, it invaded them, destroy original distribution difficult. ing or displacing sediments and lignite. The Tule Following the cessation of volcanism in the Lake flow never inundated the eastern part of region, the Blue Mountains and Troy basin the study area. Instead, it flowed northeastward continued to evolve. Saddle Mountains Basalt out of the Troy basin into the Lewiston basin, in flows and intercalated sediments were folded and a valley eroded by an ancestral Grande Ronde eroded during the development of the Saddle River (Price, 1977). Butte anticline-Grouse Flat syncline structural In response to continued structural deforma complex. tion, broad canyons or valleys were eroded into Meanwhile, the Grande Ronde River and its the surface of the Tule Lake flow. These valleys tributaries established meandering courses through were filled during the subsequent eruption of the the Troy basin. In response to regional uplift, the Mountain View flow (Buford Member). In the meandering streams became entrenched and eastern portion of the study area, where the Tule canyons formed. When the easily erodable sedi Lake flow is absent, the Mountain View flow is a mentary interbeds were encountered, the streams 250-ft-thick (7 5 m) sheet flow. In that area, the eroded laterally, forming broad valleys. Once the Mountain View flow overrode unconsolidated river and its tributaries had eroded through the sediments of the Grouse Creek interbed and interbed sediments, they again became entrenched invaded them, destroying or displacing sediments into the basalt flows and cut narrow, deep canyons. and lignite. The broad valleys, which had been eroded into Deposition of sediments in the Troy basin the interbed sediments, were left abandoned as continued following the eruption of the Mountain topographic benches, high above the present View flow. Up to 150 ft (45 m) of sediments Grande Ronde River. similar to those of the Squaw Canyon and Grouse Creek interbeds accumulated on the Tule Lake LIGNITE RESERVES AND SUGGESTIONS and Mountain View flows. These sediments are FOR EXPLORATION informally named the Menatchee Creek interbed. Throughout most of the study area, canyons Lignites in the Washington State portion of were then eroded through the Menatchee Creek the Grande Ronde lignite field are poorly exposed. sediments, often into the basalt flows which Thickness of some of the lignite beds has been underlie them. These canyons were subsequently measured, but the scarcity of subsurface informa filled by the Whitetail Butte intracanyon flow tion prohibits defining their lateral extent. For 42 Geology of the Grande Ronde Lignite Field this reason, estimation of lignite reserves in the Bench" {plate 1). Although no lignite crops out Grande Ronde lignite field is impossible at this on this bench, thick diatomaceous earth beds do. time. If stratigraphic relationships in this interbed are Future exploration in the Washington State similar to those observed elsewhere in the lignite portion of the lignite field should begin with field, lignite may be associated with the diatomite. drilling to determine the lateral extent of the Finally, the flat plateau surface of Grouse thickest known lignite bed, a 40-ft-thick (12 m) Flat should be investigated (plate 1). Because of bed at the base of the Grouse Creek interbed. time constraints, this area was not mapped during Several square miles of Grouse Creek sediments this investigation, but several outcrops of diato crop out on easily accessible benches in the study mite and carbonaceous shale were observed. area (plate 1). Preliminary mapping should be undertaken to Another target for future exploration should determine if the sediments there belong to a thin, be the bench underlain by the Menatchee Creek discontinuous sedimentary interbed or to a interbed sediments at the south end of "The thicker, more extensive one. References Cited 43 REFERENCES CITED Anderson, J. L.; Beeson, M. H.; Bentley, R. D.; Carroll, Dorothy, 1970, Clay minerals - A guide Fecht, K. R.; Hooper, P. R.; Niem, A. R.; to their X-ray identification: Geological Reidel, S. P.; Swanson, D. A.; Tolan, T. L.; Society of America Special Paper 126, 80 p. Wright, T. L., 1984, Distribution maps of stratigraphic units of the Columbia River Doell, R.R.; Cox, Allan, 1962, Determination of Basalt Group; symposium volume - selected the magnetic polarity of rock samples in the papers presented at the Regional Geology field: U.S. Geological Survey Professional of Washington symposium held at Geological Paper 450-D, p. 105-108. Society of America cordilleran section meet ing, Anaheim, California, April 1982: Wash Doel, R. R.; Cox, Allan, 1967, Measurement of ington Division of Geology and Earth Re natural remanent magnetization at the out sources Bulletin [ in preparation] . crop. In Methods in palaeomagnetism - Proceedings of the NATO Advanced Study Atlantic Richfield Hanford Company Research Institute on Palaeomagnetic Methods: Amer and Engineering Division, 1976, Preliminary ican Elsevier Publishing Co., New York, feasibility study on storage of radioactive p. 159-162. wastes in Columbia River basalts: Atlantic Richfield Hanford Company ARH-ST-137, Folk, R. L., 1968, Petrology of sedimentary rocks: 2 V, Hemphill Book Co., Austin, Texas, 170 p. Bond, J. G., 1963, Geology of the Clearwater Franklin, J. F.; Dyrness, C. T., 1973, Natural Embayment: Idaho Bureau of Mines and vegetation of Oregon and Washington: U.S. Geology Pamphlet 128, 83 p. Department of Agriculture General Techni cal Report PNW-8, 417 p. Bond, J. G., compiler; and others, 1978, Geologic map of Idaho: Idaho Bureau of Mines and Friedman, G. M., 1967, Dynamic processes and Geology Map, scale 1:500,000. statistical parameters compared for size frequency distribution of beach and river Bowles, J. E., 1970, Engineering properties of sands: Journal of Sedimentary Petrology, soils and their measurement: McGraw-Hill v. 37, no. 2, p. 327-354. Book Co., New York, 187 p. . Camp, V. E., 1976, Petrochemical stratigraphy Gibson, I. L., 1969, A comparative account of the and structure of the Columbia River basalt, flood basalt volcanism of the Columbia Lewiston Basin, area, Idaho-Washington: Plateau and eastern Iceland: Bulletin Vol Washington State University Doctor of canologiq ue, v. 33, no. 2, p. 419-437. Philosophy thesis, 201 p., 1 plate. Griggs, A. B., 1976, The Columbia River Basalt Camp, V. E.; Hooper, P. R., 1981, Geologic Group in the Spokane quadrangle, Washing studies of the Columbia Plateau; Part I, Late ton, Idaho, and Montana: U.S. Geological Cenozoic evolution of the southeast part of Survey Bulletin 1413, 39 p. the Columbia River Basalt province: Geo logical Society of America Bulletin, v. 92, Hooper, P.R., 1981, The role of magnetic polar no. 9, p. 659-668. ity and chemical analyses in establishing the 44 Geology of the Grande Ronde Lignite Field stratigraphy, tectonic evolution, and petro McKee, E. H.; Swanson, D. A.;Wright, T. L., 1977, genesis of the Columbia River basalt: Geo Duration and volume of Columbia River logical Society of India Memoir 3, p. 362- basalt volcanism, Washington, Oregon, and 376. Idaho [abstract] : Geological Society of America Abstracts with Programs, v. 9, no. 4, Hooper, P. R., 1982, The Columbia River basalts: p. 463-464. Science, v. 215, no. 4539, p. 1463-1468. Pardee, J. T.; Bryan, Kirk, 1926, Geology of the Hooper, P. R.; Camp, V. E., 1981, Deformation Latah Formation in relation to lavas of the of the southeast part of the Columbia Pla Columbia Plateau near Spokane, Washington: teau: Geology, v. 9, no. 7, p. 323-328. U.S. Geological Survey Professional Paper 140-A, p. 1-16. Hosterman, J. W., 1969, Clay deposits of Spokane Price, S. M., 197 7, An evaluation of dike-flow County, Washington: U.S. Geological Survey correlations indicated by geochemistry, Bulletin 1270, 96 p. Chief Joseph dike swarm, Columbia River basalt: University of Idaho Doctor of Kirkham, V. R. D.; Johnson, M. M., 1929, The Philosophy thesis, 320 p. Latah Formation in Idal10: Journal of Geology, v. 37, no. 5, p. 483-504. Reidel, S. P., 1978, The stratigraphy and petro genesis of the Grande Ronde Basalt in the Laval, W. N., 1956, Stratigraphy and structural lower Salmon and adjacent Snake River geology of portions of south-central Wash canyons: Washington State University ington: University of Washington Doctor Doctor of Philosophy thesis, 416 p. of Philosophy thesis, 223 p. Reidel, S. P.; Long, P. E.; Myers, C. W.; Mase, J., 40 39 Long, P. E.; Duncan, R. A. 1983, Ar/ Ar 1982, New evidence for greater than 3.2 ages of Columbia River basalt from deep km of Columbia River basalt beneath the boreholes in south-central Washington central Columbia Plateau [abstract] : Eos [abstract] : Eos (American Geophysical (American Geophysical Union Transactions) Union Transactions), v. 64, no. 9, p. 90. v. 63, no. 8, p. 173. Mackin, J. H., 1961, A stratigraphic section in the Yakima basalt and Ellensburg Formation in Ross, C. P., 1938, The geology of part of the south-central Washington: Washington Di Wallowa Mountains: Oregon Department vision of Mines and Geology Report of In of Geology and Mineral Industries Bulletin vestigations 19, 4 5 p. 3, 74 p. McDonald, G. A., 1972, Volcanoes: Prentice-Hall, Ross, M. E., 1978, Stratigraphy, structure, and Englewood Cliffs, New Jersey, 510 p. petrology of Columbia River basalt in a portion of the Grande Ronde River-Blue Mountains area of Oregon and Washington: McKee, E. H., Hooper, P.R.; Kleck, W. D., 1981, University of Idaho Doctor of Philosophy Age of Imnaha Basalt - Oldest basalt flows thesis, 407 p. of the Columbia River Group, northwest United States: Isochron/West, no. 31, Ross, M. E., 1979, Large scale strike-slip faulting p. 31-33. of Columbia River basalt in northeast References Cited 45 Oregon [abstract] : Geological Society of Stoffel, K. L., 1981, Preliminary report on the America Abstracts with Programs, v. 11, geology of the Grande Ronde lignite field, no. 1, p. 51. Asotin County, Washington: Washington Division of Geology and Earth Resources Ross, M. E., 1980, Tectonic controls of topo Open-File Report 81-6, 30 p. graphic development within Columbia River basalts in a portion of the Grande Ronde Swanson, D. A.; Wright, T. L., 1978, Bedrock River-Blue Mountains region, Oregon and geology of the northern Columbia Plateau Washington: Oregon Geology, v. 42, no. 10, and adjacent areas. In Baker, V. R.; Num p. 167-171, 174. medal, Dag, editors, 197 8, The channeled scablands - A guide to the geomorphology Russell, I. C., 1901, Geology and water resources of the Columbia Basin, Washington: U.S. of Nez Perce County, Idaho: U.S. Geological National Aeronautics and Space Adminis Survey Water Supply Paper 53 and 54, tration, p. 37-57. 141 p. Swanson, D. A.; Wright, T. L., 1983, Geologic Schmincke, H. U., 1964, Petrology, paleocurrents, map of the Wenaha-Tucannon Wilderness, and stratigraphy of the Ellensburg Forma Washington and Oregon: U.S. Geological tion and interbedded Yakima basalt flows Survey Miscellaneous Field Studies Map ' south-central Washington: Johns Hopkins MF-1536, scale 1 :48,000. University Doctor of Philosophy thesis, 426 p. Swanson, D. A.; Wright, T. L.; Camp, V. E.; Gardner, J. N.; Helz, R. T.; Price, S. M.; Schmincke, H. U., 1967, Fused tuff and peperites Reidel, S. P.; Ross, M. E., 1980, Recon in south-central Washington: Geological naisance geologic map of the Columbia Society of America Bulletin, v. 78, no. 3, River Basalt Group, Pullman and Walla p. 319-330. Walla quadrangles, southeast Washington and adjacent Idaho: U.S. Geological Survey Shubat, M. A., 197 9, Stratigraphy, petrochemis Miscellaneous Investigations Series Map try, petrography, and structural geology of I-1139, scale 1:250,000. the Columbia River basalt in the Minam Wallowa River area, northeast Oregon: Swanson, D. A.; Wright, T. L.; Helz, R. T., 1975, Washington State University Master of Linear vent systems and estimated rates of Science thesis, 156 p. magma production and eruption for the Yakima basalt on the Columbia Plateau: Smith, G. 0., 1901, Geology and water resources American Journal of Science, v. 275, no. 8, of a portion of Yakima County, Washington: p. 877-905. U.S. Geological Survey Water Supply Paper 55, 68 p. Swanson, D. A.; Wright, T. L.; Hooper, P. R.; Bentley, R. D., 1979, Revisions in strati Smith, G. 0., 1903, Geologic atlas of the United graphic nomenclature of the Columbia States - Ellensburg folio, Washington: U.S. River Basalt Group: U.S. Geological Survey Geological Survey Geologic Folio 86, 7 p. Bulletin 1457-G, 59 p. Smith, W. D.; Allen, J. E., 1941, Geology and Taubeneck, W. H., 1970, Dikes of Columbia River physiography of the northern Wallowa basalt in northeastern Oregon, western Idaho, Mountains: Oregon Department of Geology and southeastern Washington. In Gilmour, and Mineral Industries Bulletin 12, 65 p. E. H.; Stradling, D. F., editors, 1970, Pro- 46 Geology of the Grande Ronde Lignite Field ceedings of the second Columbia River East quadrangle: Geological Society of basalt symposium: Western Washington America Bulletin, v. 66, no. 6, p. 663-684. State College Press, p. 7 3-96. Waters, A. C., 1961, Stratigraphic and lithologic Waitt, R. B., Jr., 1979, Late Cenozoic deposits, variations in the Columbia River basalt: landforms, stratigraphy, and tectonism in American Journal of Science, v. 259, no. 8, Kittitas Valley, Washington: U.S. Geological p. 583-611. Survey Professional Paper 1127, 18 p. Walker, G. W., 1973, Contrasting compositions of Watkins, N. D.; Baksi, A. K., 1974, Magnetostra the youngest Columbia River basalt flows in tigraphy and oroclinal folding of the Colum Union and Wallowa Counties, northeastern bia River, Steens, and Owyhee basalts in Oregon: Geological Society of America Oregon, Washington, and Idaho: American Bulletin, v. 84, no. 2, p. 425-429. Journal of Science, v. 274, no. 2, p. 148-189. Walker, G. W., 1979, Reconnaisance geologic map Williams, Howell; Turner, F. J.; Gilbert, C. M., of the Oregon part of the Grangeville quad 1954, Petrography: W. H. Freeman and Co., rangle, Baker, Union, Umatilla, and Wallowa San Francisco, California, 408 p. Counties, Oregon: U.S. Geological Survey Miscellaneous Investigations Series Map Wright, T. L.; Grolier, M. J.; Swanson, D. A., I-1116, 1 sheet, scale 1:250,000. 1973, Chemical variation related to the stratigraphy of the Columbia River basalt: Waters, A. C., 1955, Geomorphology of south Geological Society of America Bulletin, central Washington,illustrated by the Yakima v. 84, no. 2, p. 373-385. Appendix A - Sample Locations 47 APPENDIX A SAMPLE LOCATIONS Appendix A - Sample Locations 49 TABLE 2. - Basalt and sediment sample locations Sample State County Quadrangle Location 2 Location shown on no.l (USGS 7\/t') figure ... 3 Grb 1 Wash. Asotin Mountain View Sec. 2 (7-44E); 4,888-ft elev.; summit of Anatone Butte not shown Grb 2 Wash. Asotin Saddle Butte NW1ANW'.4NW•.4 sec. 10 (6-43E); 2,900-ft elev.; cliff of chaotically 38 oriented columns Grb 3 Wash. Asotin Saddle Butte SW1.4NW1.4SE1.4 sec. 8 (6-43E); 3,430-ft elev.; roadcut 38 Grb 4 Wash. Asotin Saddle Butte SW 1.4NWl.4SW•.4 sec. 8 (6-43E); 3,600-ft elev.; hillslope outcrop 38 Grb 5 Wash. Asotin Saddle Butte SE14NW1.4NE'.4 sec. 9 (6-43); 2,850-ft elev.; gravel pit - basalt in 38 ve.rtical contact with steeply dippl.ng sediments Grb 6 Wash. Asotin Saddle Butte SW1.4NE•.4SW'.4 sec. 10 (6-43E); 2,7 20-ft elev.; roadcut of vesicular 38 to scoriaceous basalt Grb 7 Wash. Asotin Saddle Butte NW1.4SW•.4NW'.4 sec. 10 (6-43E); 2,850-ft elev.;hillslope outcrop 38 Grb 8 Wash. Asotin Saddle Butte NE1.4SW1.4SW 1.4 sec. 3 (6-43E); 3,300-ft elev.; cliff outcrop of 38 chaotically oriented columns Grb 9 Wash. Asotin Saddle Butte SE1.4NW1.4SW 1.4 sec. 3 (6-43E); 3,475-ft elev.; hillslope outcrop 38 Grb 10 Ore. Wallowa Troy NW•.4NW'.4SE'.4 sec. 31 (6-43E); 2,880-ft elev.; hillslope outcrop 39 Grb 11 Ore. Wallowa Troy SE•4NW'.4SW•.4 sec. 31 (6-43E); 2,880-ft elev.; hillslope outcrop 39 Grb 12 Ore. Wallowa Troy SE14NE•.4SW•4 sec. 32 (6-43E); 2,750-ft elev.; roadcut 39 Grb 13 Ore. Wallowa Eden SW•.4NW•.4NE•.4 sec. 36 (6-42E); 2,930-ft elev.; hillslope outcrop 39 Grb 14 Ore. Wallowa Eden NE•.4NE•.4SW•4 sec. 25 (6-42E); 2,920-ft elev.; roadcut of crudely 39 developed vertical columns Grb 15 Ore. Wallowa Troy SE•.4SE•.4NE•.4 sec. 36 (6-42E); 3,070-ft elev.; roadcut below 39 abandoned shack Grb 16 Ore. Wallowa Eden SE•.4sW•.4SE14 sec. 25 (6-42E); 3,120-ft elev.; roadcut of vesicular 39 to scoriaceous basalt Grb 17 Wash. Garfield Diamond Peak SE1.4NE•.4SE•.4 sec. 4 (6-42E); 3,960-ft elev.; road ditch 39 Grb 18 Wash. Garfield Saddle Butte NW•4SW'.4NW•.4 sec. 12 (6-42E); 3,640-ft elev.; roadcut 39 Grb 19 Wash. Asotin Mountain View SE•.4SE•.4NE•.4 sec. 20 (7-44E); 3,150-ft elev.; cliff outcrop 37 Grb 20 Wash. Asotin Mountain View SW•.4SW•.4SW•.4 sec. 16 (7-44E); 2,960-ft elev.; roadcut of platy basalt 37 Grb 21 Wash. Asotin Mountain View NW•.4SE•.4SW•.4 sec. 20 (7-44E); 3,340-ft elev.;hillslope outcrop 37 of vesicular to scorlaceous basalt Grb 22 Wash. Asotin Mountain View SW•ANW•AsW•A sec. 20 (7-44E); 3,290-ft elev.; hillslope outcrop of 37 platy basalt Grb 23 Wash. Asotin Mountain View SWl.4NW•.4SW•.4 sec. 20 (7-44E); 3,300-ft elev. ; cliff outcrop of 37 large vertical columns Grb 24 Wash. Asotin Mountain View SE•AsW•4SW•.4 sec. 20 (7-44E); 3,035-ft elev.; roadcut below barn 37 Grb 25 Wash. Asotin Mountain View NE•.4NWl.4NW'4 sec. 29 (7-44E); 2,810-ft elev.; hillslope outcrop of 37 basalt below sediments Grb 26 Wash. Asotin Mountain View NE1.4SW'.4SW•.4 sec. 28 (7-44E); 2,710-ft elev.; hillslope outcrop 37 Grb 27 Wash. Asotin Mountain View SE•.4NW•.4SW'.4 sec. 28 (7-44E); 2,824-ft elev. ; hilltop outcrop 37 at Medicine tringulation station Grb 28 Wash. Asotin Mountain View SE'.4NW'.4SE'.4 sec. 19 (7-44E); 3,080-ft elev.;roadcut of vesicular to 37 scoriaceous basalt Grb 29 Wash. Asotin Mountain View NW14NW'4SW'4 sec. 29 (7-44E); 2,800-ft elev.; narrow ravine outcrop 37 of platy basalt underlying sediment Grb 30 Wash. Asotin Mountain View SW•.4SE•.4NE'.4 sec. 30 (7-44E); 2,890-ft elev.; roadcut of crudely 37 developed vertical columns Grb 31 Wash. Asotin Mountain View SE•4NE•.4NW•.4 sec. 32 (7-44E); 2, 780-ft elev.; hillslope outcrop 37 Grb 32 Wash. Asotin Mountain View SE•.4NE'.4NW'.4 sec. 32 (7-44E); 2,750-ft elev.; hillslope outcrop 37 of vesicular to scoriaceous basalt Grb 33 Wash. Asotin Mountain View NE'.4NW'.4NW'.4 sec. 31 (7-44E); 3,525-f-t elev.; outcrop on top 37 of Whitetail Butte Grb 34 Wash. Asotin Mountain View SE•.4NW'.4NW'.4 sec. 30 (7-44E); 3,360-ft elev. ; roadcut of large, 37 vertical columns Grb 35 Wash. Asotin Mountain View NE•ASW•ANW'.4 sec. 30 (7-44E); 3,340-ft elev.; roadcut of basalt 37 intruding sandstone; sample from 1-ft-thick dike Grb 36 Wash. Asotin Mountain View NW•.4SE•.4NW•.4 sec. 30 (7-44E); 3,290-ft elev.; roadcut of basalt 37 intruding sandstone; sample from platy dike Grb 37 Wash. Asotin Mountain View NW•ASE'.4NW'.4 sec. 30 (7-44E); 3,260-ft elev. ; roadcut of large 37 vertical columns Grb 38 Wa.sh. Asotin Mountain View SE•.4SE•.4SE•4 sec. 36 (7-43E); 2,920-ft elev.; hillslope outcrop 37 of crudely developed vertical columns Grb 39 Wash. Asotin Mountain View SW'.4NW•.4NE•A sec. 1 (6-43E); 2,910-ft elev.; hillslope outcrop 37 Grb 40 Ore. Wallowa Troy NW 14NE•.4SE'.4 sec. 14 (6·43E); 2,740-ft elev.; roadcut 38 Grb 41 Wash. Asotin Troy NW'.4NE'ANE'.4 sec. 15 (6-43E); 2,860-ft elev.; hillslope outcrop 38 Grb 42 Wash. Asotin Saddle Butte NEl.4SE•.4SE•.4 sec. 10 (6-43E); 2,990-ft elev. ; hillslope outcrop 38 Grb 43 Wash. Asotin Saddle Butte NE'.4SE•.4SW•.4 sec. 10 (6-43E); 2,780-ft elev.; hillslope outcrop 38 Grb 44 Wash. Asotin Saddle Butte SE'.4NE•.4SW'.4 sec. 10 (6-43E); 2,850-ft elev.; hilltop outcrop, 38 along crest of narrow, linear hill 1 Grb· basalt sample number; Grs- sediment sample number. 2 Land descriptions ue abbreviated and given to the nearest 64th section; for example, NW•.4NW1.4NW1.4 sec. 10 (6·43E) written in full would be the northwest quarter of the northwest quarter of the northwest quarter of section 10, township 6 north, range 43 east, Willamette meridian and base. 3 The locations of the samples are shown on the maps in figure 37-39. 50 Geology of the Grande Ronde Lignite Field TABLE 2. - Basalt and sediment sample locations - Continued Sample State County Quadrangle Location 2 Location shown on no.1 (USGS 7'12') figure ... 3 Grb 45 Wash. Asotin Saddle Butte SEV..SW•ANW 14 sec. 10 (6-43E); 2,900-ft elev.; hillslope outcrop 38 of tilted, elongate columns Grb 46 Wash. Asotin Tr.oy NWI/.NE14NE14 sec. 15 (6-43E); 2,840-ft elev.; hilltop outcrop 38 Grb 47 Wash. Asotin Saddle Butte SW14SE14NE14 sec. 10 (6-43E); 3,100-ft elev.; gravel pit 38 Grb 48 Wash. Asotin Saddle Butte NE'4SW14NW14 sec. 11 (6-43E); 3,100-U elev.; hilltop outcrop 38 Grb 49 Wash. Asotin Saddle Butte NW•ANE14NW14 sec. 11 (6-43E); 3,089-ft elev.; hilltop outcrop 38 Grb 50 Wash. Asotin Saddle Butte NW 14SW'ANE14 sec. 11 (6-43E); 2,870-ft elev.; hillslope outcrop 38 Grb 51 Wash. Asotin Saddle Butte SWV..SE 14NE•A sec. 11 (6-43E); 2,820-ft elev.; hillslope outcrop 38 Grb 52 Wash. Asotin Saddle Butte NE'ASW14NW14 sec. 11 (6-43E); 3,080-ft elev.; hillslope outcrop 38 Grb 53 Wash. Asotin Saddle Butte NW14SE•ASE•4 sec. 4 (6-43E); 3,200-ft elev. ; roadcut of basalt 38 intruding sandstone; sample from 1-ft·thick dike Grb 54 Wash. Asotin Saddle Butte SWV..NE14NW14 sec. 9 (6-43E); 3,200-ft elev.; cliff of chaotically 38 oriented columns Grb 55 Wash. Asotin Saddle Butte SW•ANE14NW 14 sec. 9 (6-43E); 3,190-ft elev.; cliff outcrop of large, 38 vertical columns Grb 56 Wash. Asotin Saddle Butte SW'4NE14NW14 sec. 9 (6·43E); 3,400-ft elev.; hillslope outcrop of 38 large, vertical columns broken into smaller blocks Grb 57 Ore. Wallowa Troy SW'4NW•4SE'4 sec. 32 (6·43E); 2,740-ft elev.;roadcut of vesicular 39 to scoriaceous basalt Grb 58 Ore. Wallowa Troy NW'4SW1/,NW'4 sec. 32 (6·43E); 2,940-ft elev.; roadcut of vesicular 39 to scoriaceous basalt Grb 59 Wash. Asotin Saddle Butte NW'4NW'4SW•4 sec. 8 (6-43E); 3,550-ft elev.; gravel Pit; basalt 38 intruding sediments Grb 60 Wash. Asotin Saddle Butte NW•4SW•4SW'4 sec. 8 (6-43E); 8,180-ft elev.; hillslope outcrop 38 of platy basalt Grb 61 Wash. Asotin Saddle Butte NW•4SW14SW•4 sec. 3 (6-43E); 3,210-ft elev.; hillslope outcrop 38 of basalt intruding quartzose siltstone Grb 62 Wash. Asotin Saddle Butte NW•4SW'4SW'4 sec. 3 (6·43E); 3,200-ft elev.; cliff outcrop of 38 chaotically oriented columns Grb 63 Wash. Asotin Saddle Butte SE14NEV..SE'4 sec. 31 (7-43E); 3,860-ft elev.; roadcut of massive 38 to vesicular basalt Grb 64 Wash. Asotin Saddle Butte NW•ASW 14SW14 sec. 32 (7-43E); 3,810-ft elev.; roadcut 38 Grb 65 Wash. Asotin Saddle Butte NW'4SE•AsW•4 sec. 32 (7-43E); 3,670-ft elev.; roadcut of vesicular 38 to scoriaceous basalt Grb 66 Wash. Asotin Mountain View SE•4SW14NW14 sec. 30 (7-44E); 3,450-ft elev.; cliff outcrop of 37 vesicular basalt Grb 67 Wash. Asotin Mountain View SE•4SW•4NW14 sec. 30 (7·44E); 3,470-ft elev.; cliff outcrop near 37 the top of "The Bench" Grb 68 Wash. Asotin Mountain View NW'ASE•ANW•A sec. 31 (7-44E); 3.240-ft elev.; hillslopc outcrop 37 of vesicular basalt Grb 69 Wash. Asotin Mountain View NW•4SE•ASW'4 sec. 30 (7-44E); 3,240-ft elev.; roadcut of 37 vesicular to scoriaceous basalt Grb 70 Wash. Asotin Mountain View NE'4NW14SW14 sec. 25 (7-43E); 3,260-ft elev.; hilltop outcrop of 37 small, horizontal columns Grb 71 Wash. Asotin Mountain View NEl.4NW•4SW'4 sec. 25 (7-43E); 3,240-ft elev.; hillslope outcrop 37 of small, horizontal columns Grb 72 Wash. Asotin Mountain View NW•ANW14SW1.4 sec. 25 (7-43E); 3,150-ft elev.; roadcut 37 Grb 73 Wash. Asotin Mountain View SW14NE•ASW•4 sec. 30 (7-44E); 3,220-ft elev.; cliff outcrop of large, 37 vertical columns Grb 74 Wash. Asotin Mountain View NE14SE14NW14 sec. 30 ( 7-44E); 3,200-ft elev.; hillslope outcrop 37 Grb 75 Wash. Asotin Mountain View SW'4NE14NE14 sec. 20 (7·44E); 3 ,410-ft elev.; roadcut of vesicular 37 to scoriaceous basalt Grb 76 Wash. Asotin Mountain View SE'4SE'4NW14 sec. 30 (7-44E); 3,130-ft elev.; hillslope outcrop 37 Grb 77 Wash. Asotin Mountain View SE•ASE'4NW'4 sec. 30 (7-44E); 3,120-ft elev.; hillslope ou tcrop 37 of platy basalt Grb 78 Wash. Asotin Mountain View NE•4SE1.4NW•4 sec. 21 (7-44E); 2,920-ft elev.; hillslope outcrop 37 Grb 79 Wash. Asotin Saddle Butte SE•4NW14NE14 sec. 9 (6·43E); 2,920-ft elev.; hillslope outcrop 38 Grb 80 Wash. Asotin Saddle Butte NE'4NW14NE•4 sec. 16 (6·43E); 2,880-ft elev.; hillslope outcrop 38 Grb 81 Wash. Asotin Saddle Butte NW 14NE1.4NE14 sec. 17 (6-43E); 3,340-ft elev.; roadcut 38 Grb 82 Wash. Asotin Troy SE•.4NE14NE14 sec. 17 (6-43); 3,270-ft elev.; roadcut of vesicular 38 to scoriaceous basalt Grb 83 Ore. Wallowa Troy NW•4NW 14SE14 sec. 15 (6-43E); 2,820-ft elev.; hillslope outcrop 38 Grb 84 Wash. Asotin Saddle Butte SE14NW14SE14 sec. 8 (6-43E); 3,520-ft elev.; hilltop outcrop along 38 flat ridge top Grb 85 Wash. Asotin Saddle Butte NWl.4SW14SW•4 sec. 9 (6-43E); 3,420-ft elev.; hillslope outcrop 38 Grb 86 Wash. Asotin Saddle Butte NWV..SW 14SW14 sec. 9 (6-43E); 3,250-ft elev.; hillslope outcrop 38 of vesicular basalt Grb 87 Wash. Asotin Saddle Butte NW1ASW 14SW1.4 sec. 9 (6·43E); 3,270-ft elev.; billslope outcrop 38 of large, horizontal columns Grb 88 Ore. Wallowa Troy SE14SW14SW14 sec. 15 (6-43E); 3,190-ft elev.; hillslope outcrop 38 Grb 89 Ore. Wallowa Troy SE14NE14SEV.. sec. 22 (6·43E); 3,150-ft elev.; hillslope outcrop as Grb 90 Ore. Wallowa Troy NW•4NE14NW•4 sec. 22 (6-43E); 3,120-ft elev. ; roadcut of platy 38 basalt overlying sediments Grb 91 Wash. Asotin Mountain View SW 14SE14NW14 sec. 30 (7·44E); 3,250-ft elev.;hillslope outcrop 37 of basalt scoria Appendix A - Sample Locations 51 TABLE 2. - Basalt and sediment sample locations - Continued Sample State County Quadrangle Location 2 Location shown on no.1 (USGS 7'h') figure ... 3 Grs 1 Wash. Asotin Saddle Butte SW'.4NE•.4SW•.4 sec. 9 (6-43E); 3,040-ft elev.; roadcut 38 Grs 2 Wash. Asotin Saddle Butte NW 1ASE•ASW•A sec. 9 (6-43E); 3,040-ft elev.; roadcut 38 Grs 3 Ore. Wallowa Troy NW 1ANW'.4NE1A sec. 22 (6-43E); 2,970-ft elev.; roadcut 38 Grs4 Ore. Wallowa 'l'roy NE•.4NW•.4NE '.4 sec. 29 (6-43E); 2,960-ft elev.; roadcut 38 Grs 5 Ore, Wallowa Troy SE1.4NW'.4NW•A sec. 28 (6-43E): 2,950-ft elev.; roadcut 38 Grs6 Ore. Wallowa Troy SE1.4NW•ANE1.4 sec. 28 (6-43E): 2,920-ft elev.; roadcut 38 Grs 7 Wash. Asotin Saddle Butte NW 1ANW'ASW'A sec. 8 (6-43E); 3.540-ft elev,: gravel pit 38 Grs 8 Wash. Asotin Saddle Butte SE1ASE'.4SE•A sec. 4 (6-43E); 2,975-ft elev.: trail cut 38 Grs 9 Wash. Asotin Mountain View NW•AsE•ANW•.4 sec. 31 (7-44E); 3,320-ft elev.; ravine outcrop 37 Grs 10 Wash. Asotin Saddle Butte NE>.4NW'.4SW•.4 sec. 8 (6-43E); 3,540-ft elev.; gravel Pit 38 Grs 11 Wash. Asotin Saddle Butte NW1ANW'ASW'.4 sec. 8 (6-43E): 3,540-ft elev.; gravel pit 38 Grs 12 Wash. Asotin Saddle Butte NW1.4NW'ASW•.4 sec. 8 (6-43E); 3,540-ft elev.; gravel pit 38 Gxs 13 Wash. Asotin Saddle Butte NW1.4NW'.4 SW'.4 sec. 8 (6-43E); 3,540-ft elev.; gravel pit 38 Grs 14 Wash. Asotin Saddle Butte NW•.4NW•.4SW1.4 sec. 8 (6·43E); 3,540-ft elev.; gravel pit 38 Grs 15 Wash. Asotin Mountain View NE•.4NW•.4SW•.4 sec. 21 (7-44E); 2,950-ft elev.;roadcut 37 Grs 16 Wash. Asotin Mountain View NW•ANE•ASEIJ.i sec. 20 (7-44E); 3,220-ft elev.; roadcut 37 Grs 17 Wash. Asotin Mountain View SE1.4SE'ANE'A sec. 20 (7-44E): 3,100-ft elev.; roadcut 37 Grs 18 Wash. Asotin Mountain View SE1ASW•.4SW 1.4 sec . 20 (7-44E); 3,080-ft elev.; roadcut 37 Grs 19 Wash. Asotin Mountain View SW1ANE'ASE'.4 sec . 19 (7-44E); 3,100-ft elev.; roadcut 37 Grs 20 Wash. Asotin Mountain View SE1.4SW'.4NE'.4 sec . 30 (7-44E): 2,900-ft elev.; roadcut 37 Grs 21 Wash. Asotin Mountain View NE1.4SE1ASE'.4 sec. 30 (7-44E); 2,800-!t elev.; roadcut 37 Grs 22 Wash. Asotin Mountain View SE1ANW'.4NW'.4 sec. 31 ( 7-44E); 3,490-ft elev.: hillslope outcrop 37 Grs 23 Wash. Asotin Mountain View SW•.4SE'.4SW•.4 sec. 30 (7-44E); 3,350-ft elev.; roadcut 37 Grs 24 Wash. Asotin Mountain View SE1.4NW'.4NW•.4 sec. 20 (7-44E); 3,330-ft elev.: roadcut 37 Grs 25 Wash. Asotin Mountain View NE1.4SW•.4NW 1.4 sec. 30 (7-44E); 3,290-ft elev.: roadcut 37 52 Geology of the Grande Ronde Lignite Field N SCA LE 0 ~ ( ====fi~==~1 Mile (. FIGURE 37 . - Basalt and sedime n t sample locations map (see table 2). Appendix A - Sample Locations 53 • 25 Basalt Sample o 10 Sediment Sample SCALE 0 % ======i1 Mile T 6 N 6 ~.. -.... ,,.., 0 17 r#•• .. "" T,it.nC•111' ... , ·"" t- ~" t arUett ,,,., 21 I FIGURE 38. - Basalt and sediment sample locations map (see table 2). 54 Geology of the Grande Ronde Lignite Field T 7 N , T 6 6 N .. I 0 1,~~ "'l • I '! I "" 1 ""1 ~-·'! - ..... ;, 17 1/ sr· --'-+---., -- ·--- r.1·-1 I I l •I I 8artk1 l I I ------·;-:I I ( : ,,,,, •14 Basalt Sample t I N O===S=C::::::~i::::L=E=c=:==il MU, ~ ,r )I, • I FIGURE 39. - Basalt and sediment sample locations map (see table 2). Appendix B - Basalt Geochemistry 55 APPENDIXB BASALT GEOCHEMISTRY Appendix B - Basalt Geochemistry 57 Eighty-nine of the ninety-one basalt samples Lithium Fluoride (LiF) analyzing crystal: collected in this study were analyzed by the X-ray for Fe, Mn, Ti, Ca, K fluorescence method for oxides of Si, Al, Ca, Mg, Pentaerythritol (PET) analyzing crystal: Ti, K, P, Na, Mn, and total Fe. The analyses were for Si, Al performed in the Washington State University Germanium (GE) analyzing crystal: for P Basalt Research Laboratory under the direction Ammonium Dihydrogen Phosphate (ADP) of Dr. Peter Hooper. analyzing crystal: for Mg The samples were crushed to a fine powder Potassium Acid Phthalate (KAP) analyzing by a hydroloc press, jaw crusher, and shatter box. crystal: for Na For each sample, one part of the powder was mixed with two parts of lithium tetraborate, Standard corrections for absorption were poured into a carbon crucible, and fused into a made on the raw data. The corrected values were glass bead by placing the mixture into a 1,000°c normalized on a volatile-free basis with Fe2o3 oven for 5 minutes. The glass beads were then assumed to be 2.0 percent by weight (table 3). crushed and fused a second time, in order to The analyses were plotted on six variation dia minimize all grain size effects. grams and polygonal fields were drawn around After polishing, the beads were analyzed on chemical types (figs. 40 through 45). All flows a Phillips PW-1411 X-ray fluorescence unit with analyzed belong to one of the following three standard generator and recording units and a chemical types defined by previous workers paper-tape printout, which is fed directly into a (Walker, 1973; Wright and others, 1973): B = computer. Several crystals were used to analyze Buford chemical type; EM = Elephant Mountain the various elements: chemical type; U = Umatilla chemical type. '11 GEOCHEMICAL DATA 00 TABLE 3. - Major and minor oxide data for Columbia River Basalt Group flows in Grande Ronde lignite field, Asotin County, Washington Type Al 0 Ti0 Fe MnO CaO MgO K Na o Total Sample Si0 2 2 3 2 2o3 FeO 2o 2 P205 GRB2 EN 51.30 14.37 3.f•8 2.00 13.05 0.22 8.55 4.'•6 1.09 0.99 0.49 100.00 GRB3 EN 51.69 13.96 3.49 2.00 13.01 0.22 8.28 4.37 1.10 1.43 0.46 100.01 GRB4 B 54.28 15,65 2 l!t 2 PO 9,84 0.<'6 8 .S!i {i ZQ L.115 0 85 0 30 l DO Ol GRB5 rn 52.06 14.15 3.43 2.00 13.09 0.20 7.97 4.16 1.11 1.34 0.48 99.99 GRB6 u 55.40 15.14 2.81 2.00 10.34 0.23 6.28 2.92 2.85 1.24 0.80 100.01 GRB7 EN 51.84 14.23 3.44 2.00 12.97 0.21 8.19 4. 30 1.06 1.31 0.46 100.01 GRB8 EN 51.94 14,52__3,f,4 2,JJO l3 19 Q ,~ a 35 3 2ft l 12 0 !'fS! 0 'iO JOO 00 GRB9 B 54.52 15.27 2 . 16 2.00 9.73 0.18 8.52 4.94 1.23 1.16 0.27 99.98 0 GRB10 u 54.67 15.48 2.65 2.00 10.91 0.20 6.07 2.91 2.64 1.63 0.84 100.00 ~ GRB12 EN 51.90 14.39 3.42 2 . 00 12.80 0.24 8.77 4.46 1.06 0.53 0.42 99.99 0 0 GRB13 u 54.6L_l5.07 2.1~. oo 11.5.3__.Q....2.l 6,04 2.70 2 55 l 71 0 78 ]QQ.00 aq GRB14 u 54.29 15.00 2.70 2.00 11.15 0.22 6.16 2.73 2.78 2.09 0.88 100.00 '< GRB15 u 54.35 15.28 2.61 2.00 11. 73 0.23 6.05 2.26 2.82 1.82 0.86 100.0l ....0 GR816 u 54.27 15.05 3.15 2.00 11.14 0.20 6.95 2.93 2. 31 l. 33 0.69 100.02 .... GR817 8 24,79. 15,48 2 .l!i 2,QO 9,24 o...2.o....__asa 4,64 l 42 l 2] a 30 ]00 00 ::,- GRB18 EN 52.77 14.81 3.73 2.00 11.51 0.16 8.65 3.42 l. 22 1.21 0.52 100.00 ~ GRS19 B 54.17 15.13 2.20 2.00 10.48 0.20 8.37 4.75 1.36 1.05 0.29 100.00 ...0 II> GRB20 u 55.57 15.49 2. 72 2.00 11.58 0.16 5.15 1.80 2.80 1.84 0.89 100.00 ::s GP.821 8 54.08 16.16 2 ,gg_ 2,QQ 9.§3 0.18 §,45 4,40 1.22 l, 17 P 3Q__ l.QQ.,Jl1- 0. GRB22 B 54.66 15.40 2.12 2.00 9.56 0.19 8.32 4.88 l. 31 1.28 0.29 100.01 ~ GRB23 B 54.71 15.57 1.99 2.00 9.12 0.19 8.62 5.10 1. 31+ 1.09 0.26 99.99 ~ 0 GRB24 B 54.97 15.37 2.21 2.00 8.95 0.18 8.30 4.79 1.37 1.57 0.30 100.01 ::s GRB25 u 0,78 Q9 99 0. 54.96 15,04 2 , Zl 2 , Qo ll,08 0,20 5. 90 3,21 2,54 1,57 ~ GRB26 u 55.04 15.17 2.56 2.00 10.87 0.19 5.73 3.49 2.56 1.57 0.82 100.00 t"" GRB27 B 54.80 15.78 2.15 2.00 8.85 0.24 8.58 4.79 1.43 1.07 0.29 99.93 ~- GRB28 u 54.75 15.04 2.62 2.00 10.94 0.24 6.27 2.45 3.19 1.64 0.87 100. 01 ::s GP.829 u 55.37 15.34 2.65 2.00 10.52 Q.26 2.98 0.87 .... 6.14 6-· 32 1.54 99.99 -·~ GRB30 52.29 2.00 4.39 0.80 0.49 99.99 EN 14.75 3.50 12.13 0.19 8.32 1.13 "x:l GRS31 B 54.82 14.97 2.12 2.00 9.92 0.20 8.38 4.82 1.51 0.97 0.28 99.99 GRB32 u 56.26 15.56 2.70 2.00 9.45 o. 25 6.19 2.38 3.04 1.30 0.88 100.01 a:~ GP.B33 EN 52.11 14.06 3.29 ~.QO 1J.12 0.21 Z,94 4.03 1,16 1,22 0,50 lQQ,Ql GRB34 Etl 50.46 14.15 3.40 2.00 15.05 0.24 8.11 4.38 l. 00 0.73 0.49 100.01 GRB35 EN 52.65 14.81 3.84 2.00 13.81 0.21 7 .23 2.33 1.25 1.34 0.53 100.00 GRB36 EN 55.44 16.35 4.16 2.00 8.66 0.11 7 .65 2.07 1.40 1.59 0.57 100.00 GRB37 EM 53.54 14. 71 3.69 2.00 9.95 0.20 8.93 4.14 1.23 1.11 0. 5.Q__ lM....Q.Q. GRB38 B 54.43 15.55 2.20 2.00 9.46 0.21 8.71 4.85 1.32 0.98 0.30 100.01 GRB39 B 55.14 15.15 2.19 2.00 9.04 0.19 8.57 4.93 1.36 1.14 0.30 100.01 GRB40 u 54.83 15. 58 3.04 2.00 9. 71 0.19 5.78 2.21 2.73 3.14 0.80 100.01 GRB41 EN 51.37 14.48 3.56 2.00 11.81 0.18 8.25 3.85 1.24 2.75 0.51 100.00 GR642 B 53.98 15.51 2.23 2.00 8.94 0.19 8.34 4. 71 1.56 2.22 0.31 99.99 GRB43 EN 51.31 14. 56 3.66 2 . 00 11. 91 0.20 8.27 3.83 1.26 2.46 0 . 52 99.98 GRB44 B 53.53 15.49 2.20 2.00 9.22 0.19 8.36 4. 76 1.54 2.42 0.30 100.01 GP.845 EN 51.54 14.40 3.68 2.00 11. 99 0.20 8.23 3.72__ ]._.33 2.39 0.52 100.00 EXPLANATION OF CHEMICAL TYPE: EN=ELEPHANT MOUNTAIN B= BUFC'W. U= UMATILLA. TABLE 3. - Major and minor oxide data for Columbia River Basalt Group flows in Grande Ronde lignite field, Asotin County, Washington - Continued Sample Type Si0 Al Ti0 Fe FeO CaO MgO K 2 2o3 2 2o3 MnO 2o Na20 P205 Total GRB46 B 54.43 16.07 2. 27 2.00 7.42 0.16 8.43 4.51 1.51 2.89 0.31 100.00 GRB47 EH 50.86 14.30 3.49 2.00 12.43 0.21 8.18 4.18 1.35 2 . 51 0.49 100.00 GRB48 B 53.76 15. 27 2.24 2.00 8.86 0.18 8.39 4.79 1.56 2.63 0.32 100.00 GRB49 EH 51.19 14.46 3.58 2.00 12.28 0 , 21 8.16 4.05 1.33 2.g3 0.51 100.Q_O_ GRBSO B 53.40 15.36 2.25 2.00 9.60 0.19 8.33 4.68 1.48 2.39 0.32 100.00 GRB51 B 52.99 15.98 2.31 2.00 9.42 0.17 8.50 4.49 1.21 2.57 0. 36 100.00 GRB52 B 53.36 15.58 2.21 2.00 9.92 0.17 8.02 4.39 1.40 2.65 0.31 100.01 GRB53 EH 53.75 16.09 4.10 2.00 9.53 0.19 7.75 l.92 !-51 2.57 0.54 lQJLJ)_Q_ GRo54 EM 52.03 14.92 3.82 2.00 11.40 0.19 7.88 3.16 1. 39 2.68 0.54 100.01 GRS55 EM 49.84 13.83 3.71 2.00 13.24 0.21 8.19 4.25 1.36 2.85 0.51 99.99 GRB56 B 53. 75 15.36 2.21 2.00 9.39 0.18 8. 08 4.58 l. 70 2.43 0.32 100.00 GRB57 u 54.98 15.83 2.88 2.00 10.04 0.14 5.41 1.82 2.75 3.27 0.89 100.01 GRB58 u 53. 72 15.19 2.92 2.00 11.17 0.24 6.18 2.23 2.81 2.78 0. 77 100.01 GRS59 EH 53.01 15.53 4.07 2. 00 10.76 0.12 8.12 2.07 1.00 2.75 0.57 100.00 > GRB60 ,t:1 5P~4 H,08 3..5~. • QO 12 66 Q 2.6 Z 88 3 28 l 25 2 23 0 50 l 00 O? "O 'O GRB61 EH 51.65 14.86 3.69 2 .00 11.30 0.25 7.98 3.32 1. 35 3. 03 0.58 100.01 (I) EM 50.92 14.15 3.49 12.49 8. 07 4.00 0.49 100.00 ::, GRB62 2.00 0.21 1.21 2.97 Q. GRB63 u 55.89 15.90 2.90 2.00 7.54 0.19 6.24 2.47 2.82 3.18 0.86 99.99 ~- ~8 ~~!t Etl Sl,22 H,53 3,65 2. 0.0_--1.L..33 0 2.0--8 22 3 8] l ~43 2 63 0 lil JOO O.L_ GRB65 B 55.35 16.37 2.43 2.00 7.39 0.13 7.64 3.78 1.56 2.83 0.33 100. 01 to GRB66 EM 51.27 14.27 3.57 2.00 12.24 0.19 8. 05 3.84 1.36 2.70 0.51 100.00 I GRB67 B 52.93 15.92 2.33 2.00 9.74 0.17 8.21 4.62 1.10 2.68 0.31 100.01 0 (I) GRB68 B 53.68 15 . 35~ 1 2. 00 9,48 0, 18 8,ll 4.67--1.,51 2,50 P '51 l.0.0.• ..ll.Q._ 0 n GRB69 B 53.77 15.78 2.26 2.00 8.20 0.19 8.39 4.83 1.62 2.65 0.31 100.00 ::r GRB70 EM 51.83 15.22 3.69 2.00 9.79 0.18 8.75 4.04 1.20 2.79 0.51 100.00 (I) GR871 B 53J+9 15.47 2.23 2.00 9.45 0.18 7.96 4.65 1.47 2.80 0.31 100.01 3 GRB72 ~H 21-~3 l!f.._2 O 3,5~ 2,QO 11.28 0,19 8.Jl.4 4,0Z l . 2.2__2 ..a3__!L so 1 oa~ .ll.Q._ n GRB73 B 54.09 15.33 2.29 2.00 8 . 88 0.23 8.21 4.64 1.47 2.54 0.31 99.99 ~ GRB74 B 53.16 15.48 2.17 2.00 9.52 0.18 8.16 4.83 1.49 2. 71 0.30 100.00 t::;j I» GR875 El1 51.18 14.41 3.80 2.00 11.43 0.20 8.48 3.86 1.27 2.83 0.55 100.01 ~ GR876 B 52.57 15.gQ Z,5/l ~ .!Hl lQ , Q5 0. 21._li. ll 4,3Q 1.20 2,Zl 0,36 9.2..,_il I» GRB77 EH 50.25 14.19 3.61 2.00 12.58 0 .19 8.40 4.15 1.25 2.87 0.51 100.00 GR878 B 53.65 15.28 2.16 2.00 9.64 0.19 8.20 4.63 1.57 2.36 0.31 99.99 GRB79 B 53.94 15.50 2.22 2.00 8. 76 0.19 8. 22 4.78 1. 70 2.37 0.31 99.99 GRB80 B 53.68 15, }9 2,J.4 2,QQ 2,32 Q,19 a.22 s.a2 l.62 2.32 o.• 3o lQQ....Q.Q_ GRB8l EM 50 . 33 13.82 3.71 2.00 13.13 0.22 8.16 4.15 1.28 2.69 0.53 100.02 GRB82 B 53.62 15.60 2.21 2.00 9.53 0.18 7.98 4.52 1.45 2.57 0.32 99.98 GRB83 B 53.84 15. 52 2.17 2.00 9.16 0.18 8.26 4.75 1.48 2.34 0.31 100.01 GRB84 B 53.66 15.67 2.18 2.00 8.20 0, 12 e. "-e !t-22 J..SQ 2.~2 Q,30 92,92 GRB65 Ei1 50.11 13.63 3.63 2.00 13.14 0.21 8.44 4.06 1.36 2.86 0.54 100.00 GRB86 B 54.47 15.54 2.23 2.00 7 . 92 0.18 8.61 4.85 1.52 2.34 0.33 99.99 GRB87 EH 50.04 13.79 3.54 2.00 13.17 0.21 8.53 4.35 1.29 2.58 0.50 100.00 GRB88 B 53.31 :),5.33 2.14 2 . 00 2-22 Q.25 §.2fl 4.ZQ J..S4 -2....l.9 Q,32 lQQ,Ol GRB89 EM 50.11 14.20 3.26 2.00 12.47 0.22 8.78 4.79 1.17 2 .5{1 0.45 99.99 GR890 EM 50.19 13. 67 3. 71 2.00 13.32 0.22 8.18 4.17 l. 27 2. 76 0.51 100.00 GRB91 B 53.61 15.51 2 . 27 2.00 9.80 0.23 8.02 4.48 1.58 2.19 0.31 100.00 co"' (7) VARIATION DIAGRAMS Q 4.50 4.25 •:is •s3 1 • 59 4.00 ELEPHANT MOUNTA~N•35 \ 54ee75 0 3.75 ss. 70, 90 • 18 (1) 5 31 • \ ea1 •Gt 0 0 8•~J!i ess / (IQ / 33• •49,77 / '< 60~ ;2, 5:;_; ~;,.: 0 3.50 0 .... • 7 • 5 / :::r (1) %Ti02 ...0 ( I» 3.25 89l ::, Q. (1) :,::, 0 ::, 3.00 "------. Q. .. ~ (1) ~ •sa •63 •s,1 (IQ ::, • 6 .... 2.75 -·(1) 14,32 • • 20 • 10 •2j/ ;·""' 76 15 • • 28 ii: 2.50 BUFORO \ so / 42,46,68,69. 71.91 • 73 / • 51 2.25 2 1, 24, 38, 39, 44, 84 '-·"86/ 79, 83 ~ •s/. 82 •27•~fss 31•:r ,s2. 78 / 4 - 17, 74, 80 2.00 l23 0.26 0.33 0.40 0.47 0.54 0.61 0.68 0.75 0.82 0.89 %P205 FIGURE 40. -Ti02/P 2o5 diagram of basalt flows in the Grande Ronde lignite field. 1.0 0.9 •s1 .-20------ e10 ·~7,? •26 0.8 •S8 /~TILLA 0.7 "·'6 > 'ti 'ti 0.6 (D •59 * •36* :s •61"" C. %P205 •54 •JS* e53* ><' 43 49•6\••41 us 6: •10 "- ••8* = 0.5 • 34 47• • 60.62 • 2 • 72 • 37 * I < '• .,··7~ I» ;·... ------••••,2 .. 0.4 o· :s T78. 82. 84. 91 ~-51 0 ~o. s2 [.48. 56,69 •86 1 71 42 /65 I» •46 •67 88•• • ·:a tJ ,\••73 22 24 ~ 0.3 .e 74 •• 4 •38 •n • •39 ... 44• BO• 21• 19 • •9 •27._31 / "'a "' BUFORD 0.2 0.1 0.0 49.0 49.5 50.0 50.5 51.0 51.5 52.0 52.5 53.0 53.5 54.0 54.5 55.0 55.5 56.0 56.5 * Samples from invasive portions of the Whitetail Butte flow %Si02 FIGURE 41. - P20 5/Si02 diagram of basalt flows in the Grande Ronde lignite field. ....c,) a> ~ T102 4.50 4.25 • 36 * • 53 * •59* 4.00 •35 * e 75 e·54 3.75 • 18 * C') •37 * (!) 4S.e 61 •70 \ 0 •43 • 64 •8 • 49 • 33 0 ~ • 60 66 • .4, • 72 '< 3.50 47• •62 • 2 • 3 ~30 0..... <+ ::r %Ti02 (!) C') 3.25 ... "'::i Q. (!) ~ 0 3.00 ::i Q. (!) • 57 • 63 t"' OQ' •6 C 2.75 ~ •13 .,. (!) •29 • 20 ~32""" "l:j ;· C: 2.50 ·~6------ BUFORD 71 91 48, 69 2.25 50• • • • • 42 46•• 86 ,. 52• e 82e • • 56 e19 • •19 • 38 .. 44 ~ 21 /" 74• • 88 78• • •83 •4 •9 80 • 17 / 68.84 22• • 27, 31 2.00 •2?>/ 49.0 49.5 50.0 50.5 51.0 51.5 52.0 52.5 53.0 53.5 54.0 54.S 65.0 55.S 56.0 56.5 * Samples from~ portions of the Whitetail Butte flow %Si02 FIG URE 42. -Ti0 /Si0 diagram of basalt flows in the Grande Ronde lignite field. 2 2 3.50 3.25 •28~ UMATILLA 3.00 • 29 •6 /" 14 •• ,s 20 2.75 •40 •57 /••63 • 10 > "Q "Q 2.50 (I> Cl i::i. %K20 ... >< /" t:D 2.25 I < ...A> ;·.... 2.00 o· Cl 0 ;· (JQ... 1.75 A> •56 3 80 91•••69 "' 88 e 44• • 78•48 •42 74• 50• 68. 84•••83 46••86 •31 1.50 53* ELEPHANT MOUNTAIN 11• •82 • 73 •• • 21 .-64 •54 • 52 • 17 ;:·,.. • SS •85 •47 49• •66 45••61 \ •19 24• •39 •87 •81 43 1.25 90••11 •60 ~ ••41 ?O eJS* •62 •n • • 8 •89 • 33 ..,30 •2 • J e 5/ -._!!•~3~4______7 •_!._ 12 / 1.00 ~ • 59* 49.0 49.5 50.0 50.5 51.0 51.5 52.0 52.5 53.0 53.5 54.0 54.5 55.0 55.6 56.0 56.5 * Samples from Invasive portions of the Whitetail Buue flow %Si02 FIGURE 43. - K 0/Si0 diagram of basalt flows in the Grande Ronde lignite field. c:n 2 2 c.:, : 9.0 • 37 * •89 •38~ •2 • 86 • •17.27 •39 8,5 •87 •15 •4 • 9 ' 84 • •48, 69 • 21 """\ 50 •46 • 31 30 • •44 80 •42 • 19 • :n • 24 45 3 83 43• •41 e ••64 •s ;• •67 • 88 • • • •73 • 47 •49 •1 •74 • 78 79 •62 •66 • 76 •59* 71 68••56 8.0 •s1. 12 • 5 52• • • 82. 91 •60 S4 e •3 ELEPHANT MOUNTAIN • 65 BUFORD 0 • 53 * (I) • 36* 0 0 7.5 c,q « .....0 •35 * .... %Ca0 ::r (I) 7.0 0 .• ,6 ... "'::, Q. (I) ;:ti 0 6.5 ::s Q. (I) t"' !iii' • 32 ....::s 6.0 -·(I) "';· i:i: 5.5 5.0 49.0 49.5 50.0 50.5 5 1.0 51.5 52,0 52.5 53.0 53.5 54.0 54.5 55.0 55.5 56.0 56.5 Samples from invasive portions of the Whitetail Butte flow * %Si02 FIGURE 44. - Ca0/Si02 diagram of basalt flows in the Grande Ronde lignite field. 5.1 BUFORD •23"' • 9 ·~9 38••86 •22 4.8 89 19 27.• 31 •83 •42 ••4 •67 50• • • •68 •73 et7 71 78 •S6 4.5 •51 •82.91 •46 • 2 •12 •30 • 52 •21 / 87 • 34 e3 • 7 4.2 •90 •47 •49 •12 •10 •60, 62 • 8 3.9 43 75••••41 •64 66 .,,> •45 .,, (Q 3.6 ::, 26 C. %Mg0 •18 * ~- t:= 3.3 I • 25 < UMATILLA I»... 3.0 ;·... •s o· ::, 2.7 ;·0 ll'Q I»... !3 2.4 "' •35* •29 /•32 2.1 • 69 * •36 * 1.8 ~57 •20 1.5 49.0 49.5 50.0 50.5 51.0 51.5 52.0 52.5 53.0 53.5 54.0 54.5 55.0 55.5 56.0 56.5 * Samples from~ portions of the Whitetail Butte flow %Si02 FIGURE 45. - MgO/Si0 diagram of basalt flows in the Grande Ronde lignite field. 0) 2 (Tf Appendix C - Grain Size Analyses of Sediments 67 APPENDIXC GRAIN SIZE ANALYSES OF SEDIMENTS Appendix C - Grain Size Distribution Curves 69 GRAIN SIZE DISTRIBUTION CURVES the sediment sample. When the sample contained less than 5 percent silt and clay, it was calculated Using the procedures outlined by Bowles by the following equation: (1970) and Folk (1968), four samples of sub c\==016-084 + .05-.0'95 arkosic sandstone from the Grouse Creek and 4 6. 6 Menatchee Creek sedimentary interbeds were When the sample contained more than 5 percent sieved to determine their grain size distribution. silt and clay, it was calculated by this equation: The sands were passed through a sieve stack with GRAVEL SAND SILT CLAY pebble ranule very coarse medium fine very coarse edium fine ~o clay .... coarse fine very fme 0 "' d ai"' "' It) 0 d... d "'ai (-> "'co d ai "' It) d .... "' C,l co "' SAMPLE GRS - 25 It) It) "' 0 ..... SAMPLE GRS - 18 0 SAMPLE GRS • 24 "' SAMPLE GRS · 3 0 C,l 0 00 0 a: 0 w a: "' ..... (/) w a: z 0 0 ~ "' FIGURE 46. - Grain size distributions for samples GRS-3, GRS-18, GRS-24, and GRS-25. Appendix D - Clay Mineralogy of Sediments 71 APPENDIXD CLAY MINERALOGY OF SEDIMENTS Appendix D - X -ray Diffraction Patterns 73 X-RAY DIFFRACTION PATTERNS (1970). The samples were then irradiated on a diffraction unit consisting of a Phillips goniometer Nine sediment samples of lithologies repre (model no. 42202) and generator (model no. sentative of the Grouse Creek and Menatchee 12045b) in the Division of Geology and Earth Creek interbeds were analyzed by the X-ray dif Resources laboratory. Diffraction patterns were fraction method, to determine the mineralogic obtained on runs from 32° 20 to approximately composition of their < 2 micron size fraction. 2° 20, using CuK 0( radiation with a Ni filter, a Air-dried and glycolated samples were prepared scanning speed of 1 ° /minute, and generator for analysis by the procedure outlined by Carroll settings of 36 Kv and 16mA (figs. 47 through 55). SAMPLE GRS-1 Tan siltstone with organic fragments Cu K « X ~ 1.542.8. Kv: 36 mA: 16 Range: 300 Time tonstant: 3 Ouartz goniometer speed: 1°/minute Kaolinite 3.34A I 3.s1A" 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 DEGREES 28 FIGURE 4 7. - X-ray diffraction pattern of sample GRS-1. 74 Geology of the Grande Ronde Lignite Field 0uMtz 3.34.l SAMPLE GRS-2 I Buff, micaceous, subarkosic sandstone Cu K 0(). a 1.542,,I!. Kv: 36 mA: 16 Range: 300 Kaolinite Time constant: 3 3.55.l goniometer speed: 1°/minute "' Mica 4.98.l Amphibole? 8.69.l I \ 4 6 8 10 12 14 18 18 20 22 24 28 28 30 32 DEGREES 28 FIGURE 48. - X-ray diffraction pattern of sample GRS-2. Appendix D - X-ray Diffraction Patterns 75 Quartz /3.34.&. Kaolinite 3.56.l SAMPLE GRS-3 Butt, subarkosic sandstone Cu K « >- = 1.542.8. Kv: 36 mA: 16 Range: 300 Time constant: 3 goniometer speed: 1°/minute Amphibole? Kaolinite 8.42.B."' /7.18.&. 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 DEGREES 28 FIGURE 49. - X-ray diffraction pattern of sample GRS-3. 76 Geology of the Grande Ronde Lignite Field SAMPLE GRS·4 Brown, waxy clays tone Cu Koc>. = 1.542.8. Kaolinite Kv: 36 3.56A mA: 16 I Range: 300 Time constant: 3 goniometer speed: 1°/minute Kaolinite 7.16A / 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 DEGREES 29 FIGURE 50. - X-ray diffraction pattern of sample GRS-4. Appendix D - X-ray Diffraction Patterns 77 Kaolinite / 3.57.8. SAMPLE GRS-5 Tan to white, massive siltstone Cu K "'X ~ 1.542.8. Kv: 36 mA: 16 Range: 300 Time constant: 3 goniometer speed: 1°/minute Kaolinite 7.13.8. I 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 DEGREES 28 FIGURE 51. - X-ray diffraction pattern of sample GRS-5. 78 Geology of the Grande Ronde Lignite Field SAMPLE GRS,6 Buff, micaceous, sandy siltstone Cu K oc >. = 1.542.l Kv: 36 mA: 16 Range: 300 Time constant: 3 Kaolinite goniometer speed: 1°/minute 3.67.l "' Feldsper /3.22 A Quartz 4.25.l " 4 6 B 10 12 14 16 18 20 22 24 26 28 30 32 DEGREES 28 FIGURE 52. - X-ray diffraction pattern of sample GRS-6. SAMPLE GRS,7 Black shale Cu K oc >. = 1.542.l Kv: 36 mA: 16 Range: 300 Ouartz Time constant: 3 /3.34.l goniometer speed: 1°/minute 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 DEGREES 28 FIGURE 53. - X-ray diffraction pattern of sample GRS-7. Appendix D - X-ray Diffraction Patterns 79 SAMPLE GRS-8 Gray, subarkosic sandstone Cu K o<). • 1.542.&. Ouaru 3.34A Kv: 36 I mA: 16 Range: 300 Time constant: 3 goniometer speed: t 0 /minute 4 8 8 10 12 14 18 18 20 22 24 28 28 30 32 DEGREES 28 FIGURE 54. - X-ray diffraction pattern of sample GRS-8. SAMPLE GRS-9 White diatomite Poorly Crys1111ized Kv: 36 Si0 mA: 16 2 Range: 300 Time constant: 3 I goniometer speed: t 0/minute 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 DEGREES 28 FIGURE 55. - X-ray diffraction pattern of sample GRS-9. ' REPORT OF INVESTIGATIONS 27, PLATE 1 GEOLOGIC MAP OF THE CROSS SECTIONS GRANDE RONDE LIGNITE FIELD, " I ' i I. I, A 1>[· -;A T I (J :{ ,\ I, F I) ll \"" ASOTIN COUNTY, WASHINGTON ,~P" ) .... \ ''" STATE OF WASHINGTON , 5 X VERTICAL E)l AGGERATIO"I -·· .• ..,.. •''."" •• NORTHWEST SO UTHEAST DEPARTMENT OF NATURAL RESOURCES \ J B si""'c."""' B' ' \i ; I 3800" -- Mono,;;11,,. r - BRIAN J. BOYLE, Commissioner of Public Lands DIVISION OF GEOLOGY AND EARTH RESOURCES + ART STEARNS, Supervisor RAYMOND LASMANIS, State Geologist ,,·' • I j, ·,~ :~' .. i 1 \,', l 'c I it " • w " I ··~ S )l VERTICAL EXAGYERATIO"I '' 1 •• ,~..... ·- + " u I j, !:.' / ,I ' ' 0 • ' )., r I' i . L j 1 ' '~\! "" " C 'I - :.~· - C " ~ J ' • ' ,ool------i,00 - L---c,-----,-= .c-----,,m=·----=c---L-· • " " c> 1, ., ' ~.· L FIGURE 56. -Cross section A to A'. FIGURE 57. - Cross section B to B'. ~ \ . > ' '-, • 1· \i.. E , . • ' .I . .,, -.r ,, \' ), ' ) j I· ' r ~I r ; 'l' '\ C ' S l( VERTICAL El 5 X VERTICAL EXAGGERATION S X VERTICAL EXAGGERATION "'0RTHWEST SOUTHEAST G NORTH SOUTH G' F' 3'00' 5X VERTICAL EXAGGERATION l6oo·{ SEND IN SECTION NORTHWEST SOUTHEAST J----c,c.c---, - -· .. E E',ooo· l ••• ... ••• G,ondo Rood• \. 3400' Sbmc ... m.. , ; Sbmc C "" " '\ ' 3200' • ::~ \ \ -- " -- o\ " ~ ·~·1----s'c•c_~---"'=., '>"-~,,.. ' , = j - 2400' j______>-t,.. -· ,.• .L______c ;e,.. )(I' oooo·l ---..~.--- ,cmc.---:-~:.;-oo· .. • FIGURE 60. - Cross section E to E'. FIGURE 61. - Cross section F to F". FIG URE 62. - Cross section G to G •. C •,, ' -j,._ ~ - - Contact, dashed where approximately located J , " 5 X VERTICAL EXAGGERATION ""'·' 5 X VERTICAL EXAGGERATION ..,,..,.,_, ' NORTH J NORTHWEST SOUTHEAST J ' • " WEST EAST H' I ' SO UTH t- J600· H ,.oo· • C -- ' ... = 1 -- Syncline, dashed where approximately located - -F·t~...__: , -- ,;-· ..,,,_,""- Jec1, ol Quamo,e which is "peppered" by al;,und~nt minu1e bl.ick op.iq1,1e gr.iins. Tr.insition.il magnetic \ \ \ ~l"V io1n1> ..nd>100 , and ~11,tono WEST EAST Ellensburg polarity. 250 feet (75 meters) thlck ""' a... 11 ";,... , '"" 20• B Wl>ot<1oil BUii• llow (Sewbl Formation Tule l.Ake flow (ELEPHANT MOUNTAIN MEMBER) ..,t,;n•o,,: 03 ,. Slack, line to mediumi.[rained. equigranular basalt with scattered microphenocrysts of CQVEIUD "". ''"""0"* ,., "' WASHINGTON -- plagioclase, clinopyroxene, and more rarely opaques. Weathers to a red·brown color. •=+------''--~. f """" Normal magnetic polarity. 150 feet !45 meters) thick '" ,.,.... L _____J'----- oLm,· Grouse CrNk sedimentary k,terbecl B m,,. ~-----···-----~ Subarkosic sandstone and siltstone, diatomite, carbonaceous shale, lignite, and massive ··- Study Area kaolin ite-rich siltstone and claystone. Lignite bed al the base of the interbed reaches a maximum known thickness of 40 feet (12 meters). lnterbed is 250 feet (75 meters) thick FIGURE 69. - Section N. FIGURE 70. - Section 0. FIGURE 71. - Section P. G UMATILLA MEMBER (und;tterentiated) Consists of two flows. The Umatilla flow, the older flow. is dark blue.black, fine to medium grained, and equigranular. It weathers to an orange-brown color. The Sillusi flow is dark gray. extremely fine.grained, and microporphyritic with plagioclase microphenocrysts slightly more abundant than clinopyroxene. The Sillusi flow weathers to a pale yellow brown color and has a thick goethite-rich scoriaceous flowtop. Each flow has a normal B magnetic polarity and reaches a maximum thickn~ss of approximately 200 feet !60 meters)