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Dissertations and Theses Dissertations and Theses
1990 Subsurface and geochemical stratigraphy of northwestern Oregon
Olga Berenice Lira Portland State University
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Recommended Citation Lira, Olga Berenice, "Subsurface and geochemical stratigraphy of northwestern Oregon" (1990). Dissertations and Theses. Paper 4314. https://doi.org/10.15760/etd.6198
This Thesis is brought to you for free and open access. It has been accepted for inclusion in Dissertations and Theses by an authorized administrator of PDXScholar. Please contact us if we can make this document more accessible: [email protected]. AN ABSTRACT OF THE THESIS OF Olga Berenice Lira for the Master of Science in Geology presented May 3, 1990.
Title: Subsurface and Geochemical Stratigraphy of Northwestern Oregon.
APPROVED BY MEMBERS OF THE THESIS COMMITTEE:
Richard E:hOms
Lithological, geophysical, paleontological and geochemical methods were used in order to define the contact relationship between the Keasey and the Cowlitz formations in northwestern Oregon. Drill cuttings from six wells located in Columbia County were analyzed by the Instrumental Neutron Activation Analysis (INAA) method. The 2 concentrations of K, Th, Rb and Sc/Co ratio in the samples established four different groups: 1) High K, Rb, and TH, with low Sc/Co ratio typical of Cowlitz sediments. 2) Low K, Th and Rb and high Sc/Co ratio, more characteristics of the Keasey Formation. 3) Very low concentrations of Rb and high Sc, which is indicative of basaltic volcanism. 4) vertically varying K, Th and Rb concentrations. The provenance of group four is uncertain, but it may represent reworked sediments or the interf ingering of the Keasey and the Cowlitz formations. Plots of these elements vs. depth define the geochemical contacts between the formations. The contact was also determined by interpretations of geophysical logs, the gamma ray log being the most useful. This log responds to chemical differences between the Cowlitz Formation and the Keasey Formations or local volcanic sediments. The apparent interfingering of these two formations is observed in wells drilled off the Nehalem arch of Armentrout and Suek (1985). In the upper part of the arch the Cowlitz Formation has been eroded. Therefore, the contact between the Cowlitz and the Keasey formations can be defined as conformable where they apparently interfinger and unconformable where erosion or nondeposition is evident. The contact between the Keasey and Cowlitz formations, as interpreted from the geochemical data and gamma ray logs, is the same and seem to reflect a lithologic break. 3 However, the paleontological time boundary between the Refugian and Narizian stages does not coincide with the formational boundary in all the wells, but occurs within the Keasey Formation. Therefore, Keasey Formation was deposited during both Narizian and Refugian time. In localities where the geochemical, paleontological, and lithological contacts coincide an unconformity is defined. SUBSURFACE AND GEOCHEMICAL STRATIGRAPHY OF NORTHWESTERN OREGON
by OLGA BERENICE LIRA
A thesis submitted in partial fulfillment of the requirements for the degree of
MASTER OF SCIENCE in GEOLOGY
Portland State University 1990 TO THE OFFICE OF GRADUATE STUDIES: The members of the Committee approve the thesis of Olga Berenice Lira presented May 3, 1990 •
./James G. Ashbaiigh / l
c. William Savery, Interim Vic Provost for Graduate Studies and Research. / ACKNOWLEDGMENTS
I want to acknowledge and thank the faculty of the Geology Department, Portland State University, and especially to Dr. Marvin Beeson for his encouragement, advice, dedication, friendship, and critical review of this research topic. Thanks to Dr. Gilbert Benson who initiated the study. I would like to express my gratitude to Jack Meyer from Oregon Natural Gas Development Corporation for his invaluable help and advice. Ors. Ansel Johnson, Richard Thoms, and Robert Van Atta my thanks for their collaboration and review of the thesis. Also I would like to extend my appreciation to Dennis Olmstead and Dan Wermiel from the State of Oregon Department of Geology and Mineral Industries for their assistance; Technical assistance by Michael Pollock and Gene Pierson is also appreciated and thanks to Dr. John Allan and Tom Taylor for addicting the thesis and to Keith Brunstand for his computer assistance. I dedicate this work to my parents, Jesus Dario Lira and Carmen Reyes and thank them for the years of love and understanding, financial aid and moral guidance thoughout my life. TABLE OF CONTENTS
PAGE ACKNOWLEDGEMENTS • . • • . • ...... • • . • • • • • . . . . • . • • iii
LIST OF TABLES...... vi LIST OF FIGURES.. . • . . . • . • . . • • • • • • . • • • • . . . • . • • • vii
LIST OF PI.ATES...... • . . • . . . . • . • . . . . . • ...... ix
INTRODUCTION. • . • • • . • . • • . . . . . • . • . . . • ...... • • . . . 1
Purpose ...... 2 Previous Work ...... 5 General stratigraphy of the study Area.... 7 Hydrocarbon Potential...... 8
REGIONAL LITHOSTRATIGRAPHY...... 11
Tillamook Volcanics...... 11
Hamlet Formation (also called Yamhill
Form.ation) ...... 13
Cowlitz Formation...... 17
Keasey Formation. . . • ...... 2 2
The Jewell Member of the Keasey Formation. 24
Pittsburg Bluff Formation...... 25
Scappoose Formation...... 27
Columbia River Basalt Group •.•.•..•..•..... 28
Smuggler Cove Formation ..•.•.•••••.••••...• 28
Sager Creek Formation •.•.••..•..•.•.•.•..•. 30 v Astoria Formation .•..••••...... 31
Troutdale Formation ••. 32
BIOSTRATIGRAPHY .••....•••.•••••. 34
ANALYTICAL PROCEDURES ••• 37
Geochemistry...... 3 7 Geochemistry Data and Discussion ••••••••••• 41
SUBSURFACE ANALYSIS ••••.•••••••••. • • • • • * • • • • • • • 66
Subsurface Correlation •••••••.. 66
Cross Section Interpretation •• 72
DISCUSSION AND CONCLUSION. 76
Conclusion ...... 78 Problems and Suggestions •••••.•••..•.••.••. 79
REFERENCES...... 80 APPENDIX ...... 85 LIST OF TABLES
TABLE PAGE
I Geochemistry, Oregon Natural Gas
IW 22d-10...... 43
II Geochemistry, American Quasar
Petroleum Corp. Longview Fiber #25-33 •.. 46 III Geochemistry, American Quasar Petroleum Corp, Crown Zellerbach #30-33. 48
IV Geochemistry, Exxon Company- USA.
G.P.E. Federal Com.# 1 .•••...... •..•. 51 V Geochemistry, Reichhold Energy Corp. Crown Zellerbach #2.. • • • • . . . . . • ...... 56
VI Geochemistry, Arco Oil and Gas Company
Columbia County #31-8 ..•••.•••....•..•.. 58
VII Geochemistry, Oregon Natural Gas. IW 220-10. Core samples .••.••.••.....•.• 62 VIII Geochemistry, Sc/Co ratio ••.•.••....••..•.. 63 LIST OF FIGURES
FIGURE PAGE
1. Map showing well locations in
the study area ...... 4
2. Regional stratigraphic correlation •.•..•.•. 12
3. Biostratigraphy of fourteen wells
drilled in northwestern Oregon showing the contact between the Refugian and
Narizian Stages...... 36
4. Regional Bouguer gravity map for northwest Oregon and southwest
Washington showing the location of the
Mist gas field on the east flank of the
northern Coast Range gravity high...... 39
5. Variation of elements concentrations
with depth. IW 220-10 ••.•..•..•.•..... 45
6. Variation of elements concentrations
with depth. Longview Fiber #25-33...... 47
7. Variation of elements concentrations
with depth. Crown Zellerbach #30-33.... 49
8. Variation of elements concentrations
with depth. GPE. Federal Com. #1...... 53 viii 9. Sc vs Th. Comparison of GPE. Federal Com. #1 basalts with basalts from other sources ...... 54 10. Variation of elements concentrations
with depth. Crown Zellerbach #2 . ...•... 57 11. Variation of elements concentrations with depth. Columbia County #31-B •••••. 60 12. Influence of local basaltic volcanics based on Sc concentration...... 62 \
LIST OF PLATES PLATE I Subsurface stratigraphy of northwestern Oregon. Cross section 1. II Subsurface stratigraphy of northwestern Oregon. Cross section 2. INTRODUCTION
Northwestern Oregon has been the focus of intensive gas
and petroleum investigation since the discovery of economic
quantities of natural gas in the Clark and Wilson sandstone
unit of the upper Eocene Cowlitz Formation by Reichhold
Energy near Mist Oregon in 1979 (Newton, 1979; Armentrout
and Suek, 1985).
The Cowlitz Formation consists of two units: the first
is a basal fine grained arkosic sandstone containing small
flakes of mica, which is named the Clark and Wilson sand and
which is the gas reservoir in the Mist Field (Columbia
County) ; the second is an overlying unnamed sequence of
siltstone and sandstones (Newton,1979; Bruer and
others,1984; Armentrout and Suek 1985; Niem and others
1985). The Cowlitz Formation is overlain by the Keasey
Formation which consists of tuffaceous mudstone and
siltstone with minor volcaniclastic sandstone.
The contact relationship between the Cowlitz Formation
and the Keasey Formation has been described as unconformable
in both surface and subsurface sections based on lithology,
the abrupt change from Narizian to Refugian microfauna, and
geophysical logs (Newton, 1979; Van Atta, 1971; Armentrout
and Suek, 1985; Niem and others, 1985). However, Harry John
Meyer from Oregon Natural Gas (personal communication, 1989) 2 observed an interbedding relationship in one core and in the gamma log from a well in the Mist field. Leonard Farr (1989) describes the contact as conformable to slightly disconformable, based on the gradational compositional changes between the Cowlitz and Keasey formations in several localities in the southwest corner of Clatsop County. Because the Clark and Wilson sandstone of the Cowlitz Formation represents the gas reservoir in the Mist area, and the upper mudstone and siltstone member of the Cowlitz and Keasey formations the seal, the contact between these two units is critical for petroleum exploration in Oregon.
PURPOSE
A stratigraphic cross section of northwestern Oregon was published in 1984 by the Northwest Oregon sub-committee of the Pacific Section of the American Association of Petroleum Geologists (AAPG) Committee on cross sections (Bruer and others, 1984), based on lithologic, paleontologic and well log correlations. This cross section extends from the Astoria area through Mist, to Portland and south along the Willamette Valley. The purpose of this investigation is to analyze in detail a critical part of the (AAPG) cross section from Clatsop county to Washington County (1984) in order to define the contact between the Cowlitz and Keasey formations and its relation to the Refugian/Narizian biostratigraphic 3 boundary. The following techniques were used to address this problem: a) study of the lithology of well cuttings b) critical review of available paleontological data c) detailed analysis of well logs (mud, electric, SP, gamma, and others) d) analysis of certain major and trace element concentrations in the samples by neutron activation analysis. For this investigation, I used some of the well logs and samples used by the AAPG committee, and also several well logs and samples that were drilled in the area after the cross section was published. Well data and samples were provided by Oregon Natural Gas Development Corporation, and the Department of Geology and Mineral Industry of Oregon (DOGAMI). The study covers the lower Columbia River area which includes the Astoria basin near the coast and the upper Nehalem River basin to the east, as well as the northern Willamette Valley basin, bordered on the west by the Coast Range and on the east by the Cascade Mountains. The locations of the wells are shown in figure 1. Most of them are located in the Mist area. 4 INDEX MAP NORTHWESTERN OREGON Study area
WELLS LOCATIONS I F.lCHHOLD ENERGY CORP. CLATSOP COUNTY ~own Zellerbach 134-26 ittsburg Area, SEl/4 Sec 26,T5N-R4W CLATSOP A OREGON NATURAL GAS DEVELOPMENT CO. rom center od sec. 1255' S; 632' E Patton #32-9 1ev. 898' KB Olney Area, NE Sec 9,T7N-R8W l,500 1 FNL; 2,000' FWL J . J'. TCHHOLD ENERGY CORP. Elev. 752 • KB dcown Zellerbach #2 ~i/4Sec. 4, T4N-R3W B DIAMOND SHAMROCK CORP, tom Wl/4 corner 159' s: 427' E Clatsop County 133-11 lev. 689' KB -~---- F ishhawk Creek Area, SEl/ 4 Sec.: 11, T6N··R6W 1,858' FSL; 1,845' FEL K XXON COMPANY - USA s ., Elev.940' KB. cl.~>.E. Federal Comp. # 1 Range e 4 Bw~ker Hill Area, SE1!4 Sec J, T4N-R3W <:OLUMBIA COUNTY 8 .'..::I F.<;L; l. 960 I FEL E'ile 'J. 1, 760' KB . • '"l. c ARCO OIL ANO GJl.S COMPANY Coluru.bia <:ounty f31-8 N /\!!'ERICAN QUASAR PETROLEUM COMFAN'i. Mist Gas Field, NEl/4 Sec 8,T6N-RSW H1.J.:1a F.T AL No 5-23 660' FNL; l,liOS' FEL 1-lil..i.' nort!1 & 1964 east ;:lf the southwest of: -_rr'_.r~ASHINGTO Elev. 715' Gr s~~ 5, T6N, R4W. E,lev. l,500 KB llis D OREGON NAT!JRAL GAS IW-220-10 WASHINGTON! :otm'l'i 1------i._ Mist Gas Field, Sec 10, T6N-R5W ~-, 1 2 FW corner, 285 N; 2516'E L ~l'.':TEXAS CO. Tl LLAMOOJ< 11 -i,_ Elev. 798.8' KB C1~per Mountain 11 · B , ;vect:un Area, SEl/4 Se~ 25,TlS-R2W E REICHHOLD LN£RGY CuRP, E .'. :. v. 7 8 3 ' KB Columbia County #32-tO _ ·-"'-, Mist Area, ~El/4Sec 10, T6N-R5W MARION COO~i1'Y \ 2,181' FNL; 1,745' FEL r--- Elev. 817 KB. M ~;! ClfHOLD ENERGY CORP, ( \o Figure 1. Map showing the wells locations in the study area. 5 PREVIOUS WORK The geology of northwestern Oregon was first examined by Dana (1849). Diller (1896) described the dark shales with abundant volcanic material exposed in cliffs along Rock Creek (now the Keasey Formation) and determined it to be Eocene based on fossil content and the overlying fossiliferous sandstone of the Pittsburg Bluff Formation. A geologic map of northwestern Oregon was published by Warren, Norbisrath and Grivetti, of the U.S.G.S. in 1945 as part of an oil and gas exploration project. Warren and Norbisrath (1946) described the Tertiary stratigraphy of the upper Nehalem River basin in northwestern Oregon, dividing it into the Tillamook Volcanic Series, Cowlitz, Keasey, Pittsburg Bluff, and Scappoose formations each separated by an unconformity. The Siletz River Volcanic Series and its relationship to the Tillamook Volcanic Series in northwestern Oregon was studied by Snavely and Baldwin (1948). Deacon (1954) re-examined the definition of the Keasey and Cowlitz formations at Rock Creek. He proposed that the name Cowlitz be dropped for Eocene strata in northwestern Oregon and that the late Eocene strata be called the Rocky Point Formation in the upper Nehalem basin. Wells and Peck (1961) compiled a geologic map of Oregon west of the 121st meridian, and differentiated the Miocene basalt, Eocene volcanics, Cowlitz Formation, and Astoria 6 Formation. In 1964, Bromery and Snavely analyzed gravity and aeromagnetic data and provided information about the thickness, depth of burial, and subsurface distribution of the lower to middle Eocene volcanic rocks in northwestern Oregon. Newton (1969) published a complete report of the subsurface geology of the lower Columbia and Willamette basins. Here the subsurface stratigraphy and well correlation of each particular basin was studied in detail. The sedimentary petrology of some Tertiary formations in the upper Nehalem River basin was studied by Van Atta (1971). In 1973, Beaulieu published a regional study of potential geologic hazard of eastern Tillamook and Clatsop counties. He divided the Eocene volcanic rocks of inland Tillamook and Clatsop counties into three units. Newton and Van Atta (1976) described the stratigraphy of the area in their report of prospects for natural gas production and underground storage of pipe-line gas in the upper Nehalem River basin, Columbia and Clatsop counties. The subsurface correlation in the Mist area was published by Newton in 1979. Kadri (1982) described the stratigraphy of the Mist area and distinguished the Keasey Formation from the underlying Cowlitz Formation on the basis of lithology and geochemistry. Thoms and others (1983) described the stratigraphy and the paleontology of the Yamhill, Spencer, Pittsburg Bluff, and Astoria formations in the western Tualatin Valley south of the upper Nehalem River basin. 7 Armentrout and others (1983) published a stratigraphic and chronological correlation for western Oregon and western Washington as part of the AAPG COSUNA project. The most recent work in the Clatsop, Columbia and Tillamook counties has been done by graduate students of Oregon state University under the guidance of Dr. Alan Niem and by graduate students of Portland State University under the guidance of Ors. Robert Van Atta and Richard Thoms. GENERAL STRATIGRAPHY OF THE STUDY AREA Armentrout and suek (1985) in describing the stratigraphy of northwestern Oregon, divided the rocks into four unconformity-bounded sequences, each representing a tectonically-controlled depositional cycle. The oldest sequence consists of volcanic and sedimentary rocks which are assigned to the lower to middle Eocene Siletz River Volcanics, the middle Eocene Tillamook Volcanics and middle Eocene Yamhill Formation, which later has been informally called Hamlet formation by Niem and others (1985) and Rarey (1988). These rocks are overlain by a second sequence which includes middle Eocene Cowlitz, upper Eocene-lower Oligocene Keasey, lower Oligocene Pittsburg Bluff and upper Oligocene to Miocene Scappoose Formation, which is a sedimentary sequence with subordinate interfingering volcanics. This mid-Tertiary unconformity-bound package consists of forearc 8 sedimentary rocks and locally derived arc-related volcanics. These rocks were deposited in a shelf margin basin where they are conformable within depositional lows and unconformable along structural highs. The third unconformity-bound sequence consists of basalt of the Columbia River Basalt Group interbedded with the fluvial and marine sediments of the Miocene Scappoose and Astoria formations. After the end of middle Miocene time, compressive forces caused folding of marine rocks in western Oregon. These folds trend mainly north to northeast. The Pliocene Pleistocene Troutdale Formation fluvial deposits were restricted to local downwarps along the river valley and to coastal embayments by the folds (Armentrout, 1985; Mckee, 1972; Newton 1969). HYDROCARBON POTENTIAL The Mist gas field represents the only commercial gas producer in Oregon. It is located in Townships 6 and 7 West in Columbia County on a saddle formed by the Tillamook Highland to the south and the Willapa Hills uplift to the north. It is flanked on the west by the Astoria basin and on the southwest by the Tualatin basin, which is also known as northern Willamette basin (Olmstead, 1985). The Clark and Wilson sandstone of the Cowlitz Formation is the producing interval in the field, the productivity of 9 which is directly related to its mineralogy and depositional environment. It consists of micaceous-arkosic sandstone with a porosity range of 18-32%, averaging 25%, and a permeability range from 19 to greater than 1,500 md, averaging 200 md. These high values of porosity and permeability are attributed to the lack of volcaniclastic grains, thus causing a relative absence of authigenic pore filling minerals (Armentrout and Suek, 1985). The late Eocene transgressive shale of the upper Cowlitz and Keasey formations overlying the Clark and Wilson sandstone provides a stratigraphic seal of the reservoir. Faults also work as seals. Armentrout and Suek (1985) concluded that the gas in the Mist area was thermally generated, based on the gas wetness and 13C values and originated in the deepest part of the Astoria and/or Tualatin basin, with migration up to the the reservoir. The traps in the field area consist of closure against faults, shale encased sandstone stratigraphic traps, and canyon-filled shale seals of erosionally truncated reservoirs (Armentrout and Suek, 1985). The Mist area contains at least 13 gas pools, the most important of which are the following: The Bruer pool (Columbia County well 1,3, and 6 Sec. 10 T6N, RSW), the Newton pool (Longview Fiber well 12-33 Redrill 1, Sec. 33, T7N, R5W), and the Flora pool (Columbia County wells 10 and 33-3, Sec. 3, T6N R5W) (Armentrout and Suek 1985). 10 Total production of the Mist field since its discovery has been 37,069,330 Mcf. During the last year (Sept 1988 through August 1989), total production was 2,701,425 Mcf (Northwest Oil Report, Oil/Gas and Geothermal Explorarory Activity, Vol.31 Nov 9/1989). REGIONAL LITHOSTRATIGRAPHY The following lithological description represents the stratigraphy of the study area penetrated by the wells used in this investigation. Please refer to Wells and Peck (1961) geologic map of western Oregon for regional geology. Figure 2 shows the regional stratigraphic correlation of the study area. TILLAMOOK VOLCANICS The middle to upper Eocene Tillamook Volcanics are the oldest rocks of the northwestern Coast Range, and represent the basement and core of the northward plunging anticlinal fold in northwestern Oregon. The Tillamook Volcanics consists of lower, middle and upper units. The lower unit is composed mainly of basaltic pillow lava, submarine breccias and tuff, and interbedded sedimentary rock. This lower pillow basalt is correlative with the pillow basalt of the lower Siletz River Volcanics of the central Oregon Coast Range and the Roseburg Formation of southern Oregon (Warren and others, 1945; Newton and Van Atta, 1976; Magill and others, 1981). The middle unit consists of tuffaceous siltstone, sandstone, basaltic tuff, pillow lavas and breccias. This unit probably is the equivalent of the uppermost Siletz River Volcanics, Yamhill 12 --~~~~~...-~~...-~~~~~~~~~~~-.~~~~~~~~~~~--~- - ~~~~~~~~~~..-~~~~~~~~~~--...-~~~~~~~~~~~r-~~~~~~~~~~~-w 2 I 3 4 I · 5 BENTHIC C L ATSOP COLUM BI A SW COLUM BJA I E UGE NE: SW. WfASHINGTON FORA MINI FERA COUNTY COUNT Y NW WASHINGTON AREA STt TE STAGES COUNTIES ' '4r inr ar,c ;: ...·J'1a: C::c;x:i~uts • r i ;: ..: :.; :~slsts l " nwia! dc:csns HAL"TA:N I I I I n. iv:..i: ~e'J(.s::.':5 :; e 1 1 1 1 WHEELERIAN ~ '•!------?· - "" v{NTURIAN REPETIAN Tro;;t do.le Fm. !'rout dale rm Tro iJtd.il e Fin. ...... i I '"i• 1 '""' I "i F -f DELMONT JAN r MOHNIAN PU'LJ:\· "IP..ll'.ber S..J.lle 1".tn . Basalt Panoira '1embej ' ard1e Hrr.. Sdsalt · ~ r ' ~ \:r.::.a ~ Jl!:. t,;?.-.(.!' !~~!.>t?r r.sTOria I. . t:!'.';>er 11el!'ber Colt31"bia River ~· frer~ch'MnS .~. ~.ber s frenchr:ian s LUISI AN Basdl t ~ RELIZIAN ~ "lel'Dn.!e 3.15 .il t ~ Grande l\:ln'1t! Bd.sal r -1~l- ! r SAUCESIAN A~tor~a Fm. ., I Ast:c.ci.;.a ( ? ) Fl!l. a w ~nn1.. i I 0 I I ~ -4 ::) : I L)__ l_l_~l I ~ I,() I J_l___ t all Northrup Creel< f ln. 0 z I I ZEMORRIAN Q) Scap;ioose F'm. ... 1..i nc.."Cl 1 Cn :ek !m. ~----- ... (/) I 1 ;:J u m · rl Smuggl~rCove Hn. i::· cu iil rl :.) ... rl ... (J I •rl > Pittsb urg ...J Bl'.J.ff Fm. 1----- 1 Pctt s burg 31'1ff Fh. !:u;;=e ~m.fishe r nn. REFUGIAN -._:eas <'V F\':I. -l ::O>Y..easev :':".. :;c: :e ~::'.e~•. :..::~ F':'. ? f ~Cole~. bas.lit J Vol::dm cs Spencer F;-.• Cowli t z rm. !-1.a.':'.let ~ .. NARIZIAN I .. ·-·--- ....- b-=.- I ':'ill;0.-xok Ti::.la."'.'{X)k ·:o::.canics Yarrhi ll rm. i r45 Y Figure 2. Regional stratigraphic correlation. Data from: 1. Rarey, 1985, 2, 4, 5. Armentrout and others, 1983, 3. Farr, 1989. 13 Formation and Tyee Formation to the south (Magills and others, 1981). The upper unit is composed of subaerial lava flows which are high Ti02 tholeiite and andesite in composition. (Jackson, 1983; Safley, 1989). In the upper Nehalem Valley, the Tillamook Volcanics constitute the highland southwest of the Wolf Creek Highway and are discontinuously exposed northward. The thickness is about l,OOO feet. The middle section in this area consists of dense grayish black basalt and altered submarine flows which are in fault contact with the lower Cowlitz Formation (Newton and Van Atta, 1976). In the subsurface of Columbia County, the Tillamook Volcanics interfinger with arkosic sandstone and mudstone of the Yamhill Formation (Bruer and others, 1984). The Tillamook Volcanics are thought to be fissured flood-basalt or oceanic island basalt which erupted on the ocean floor (Magill and others,1981). Paleomagnetic investigation of the Tillamook Volcanics (1981) indicates that the magnetic field direction of this unit has been rotated 46 degrees clockwise from the expected direction (Magill and other,1981). HAMLET FORMATION (ALSO CALLED YAMHILL FORMATION) The basal conglomerate and mudstone sequence underlying the Clark and Wilson sandstone of the Cowlitz Formation and overlying the Tillamook Volcanics has been described and named by several investigators. The nomenclature used for 14 this unit differs from one author to another. In the Upper Nehalem basin, Warren and Norbisrath (1946), Van Atta (1971) and in Washington county, Jackson (1981), called this section the basal conglomerate and lower shale member of the Cowlitz Formation based on outcrop descriptions. In the Mist gas field area in the subsurface, Bruer and other (1984) called this section Yamhill Formation. Al-Azzaby (1980), and Thoms and others (1983) also gave this name to the sedimentary rock directly overlying the Tillamook Volcanics in Washington County. Rarey (1986), Safley (1988), Niem and others (1985), and Farr (1989) described the outcrop and subsurface lithology in the eastern Clatsop and southern Columbia and northern Washington counties and informally referred it as Hamlet formation. The Yamhill Formation crops out in Washington and Yamhill counties (Thoms and others, 1983; AL-Azzaby, 1980), and is believe by Bruer (Bruer and others, 1984) to be present in the subsurface of the Mist gas field area in Columbia County. The type section is along Mill Creek and the Yamhill River in the central Oregon Coast Range. The Yamhill Formation consists of bedded medium- to dark-gray mudstone and siltstone, with interbedded arkosic, glauconitic and basaltic sandstone (Al-Azzaby, 1980; Thoms and others, 1983). In the Mist area, two sandstone units have been recognized: The Clatskanie sand member and the Lower Yamhill sand member. The mudstone and arkosic 15 sandstones of the Yamhill overlie and interfinger with the Tillamook Volcanics, and toward the south unconformably overlie the Siletz River Volcanics (Bruer and others,1984). The Yamhill Formation mudstones may have potential as hydrocarbon source rock, and the Yamhill sandstone as reservoir rock (Armentrout and Suek, 1985). In the northern part of Oregon (Clatsop and north of Washington counties), the name Yamhill seems to be abandoned, and the name "Hamlet formation" is used for the rocks overlying the Tillamook Volcanics and underlaying the Cowlitz Formation (Rarey, 1986: Farr, 1989) 1 The provenance of the Yamhill Formation was a combination of a proximal tholeiitic basaltic source and more distal plutonic granitic terrain. The volcanic source is indicated by the abundance of basaltic rock fragments, brown hornblende and idiomorphic zircon. The foraminiferal assemblage indicates a Narizian Stage age for the Yamhill Formation. The depositional environment of the lower part of the Yamhill Formation has been interpreted as bathyal and the upper part as marginal marine (McKeel 1984, 1985). The Yamhill Formation has been intruded in many places by porphyritic augite basalt, with the vugs filled with calcite crystals. The age of these intrusions is probably late Oligocene or early Miocene (Al-Azzaby, 1980). In Washington County, the Yamhill Formation is overlain by the Spencer Formation which consists of two members: A 17 eastern Washington and Idaho, and transported via an ancestral Columbia River drainage to the shoreline (Rarey, 1986). The Sunset Highway member could be equal to the Clatskanie sandstone of the Yamhill Formation which is named from its occurrence in the Clatskanie No. 1 well in Columbia County (Bruer and others ,1984), below the Clark and Wilson sandstone in the Mist area. The upper, Sweet Home Creek member is composed mainly of micaceous and carbonaceous silty mudstone and minor thin bedded turbidite sandstone deposited in a middle to upper slope environment. Warren and Norbisrath's (1946) lower mudstone of the Cowlitz Formation is equivalent to the Sweet Home Creek member of Niem and Niem (1985). The bathyal benthic foraminifera collected indicate a late Narizian age. The three members of the Hamlet formation reflect a gradual marine transgression over the Astoria basin (Niem and others, 1985). Regionally the Hamlet formation crops out in an arcuate pattern around the uplifted basement rocks of the Tillamook Volcanics in northern Tillamook, southern Clatsop, southern Columbia, and northern Washington counties (Safley, 1989). COWLITZ FORMATION The Cowlitz Formation in northwestern Oregon was first mapped by Warren and others (1945). It consists of sedimentary rocks composed of basaltic conglomerate, 18 siltstone, mudstone, sandstone and some intercalated volcanic fragments. It has a thickness of more than 300 meters. On the basis of the lithology, warren and Norbisrath (1945) divided the Cowlitz Formation into four members: A basal conglomerate member, a lower shale member, a sandstone member and an upper shale member. The Cowlitz Formation crops out in eastern Clatsop, northern Washington and southern Columbia counties. It interfingers with the Tillamook Volcanics (Jackson, 1983). In the subsurface of the Mist field, the Cowlitz Formation has been restricted to two units by Bruer and others (1984), a sandstone unit and a mudstone unit. The sandstone unit is represented by two subunits called the Clark and Wilson sand (lowermost) and the Upper Cowlitz, separated by a dense claystone layer (Bruer, 1984). This restriction has been followed by Rarey, 1986; Niem and Niem, 1985; Safley, 1988, and Farr, 1989. The most abundant elastic constituents of these sandstones are 34 to 46% feldspar (plagioclase), 21 to 36% quartz (microcrystalline) and 4 to 14% mica (muscovite and biotite). Amphiboles, pyroxenes, and epidote group minerals are also present in the sand. Rock fragments constitute a small percentage volcanics being the most abundant (Van Atta, 1971; Jackson 1983; Timmons 1981). The two sandstones can be distinguished from each other based on petrology: The Clark and Wilson sand is rich in zircon, and the upper sand 19 is rich in epidote (Safley, 1988). ,The abundance of mica in the Cowlitz aids in distinguishing it from the overlying Keasey Formation which is poor in mica. Based on petrology, Van Atta (1971) reported a metamorphic and plutonic provenance for the Cowlitz Formation. Later investigators such as Jackson (1983), Timmons (1981), Nelson (1985), Newton and Van Atta (1984), Olbinski (1983), and Farr (1989) agreed with this interpretation. The potential sources for the sediments are in the north Cascades of Washington, the Idaho Batholith, and the Blue Mountains, transported by an ancestral Columbia River to the forearc basin in which the Cowlitz Formation·' ' was accumulated. Longshore currents could have redistributed the sediments to the north and south of the river mouth (Van Atta, 1971). Contact relationship The Clark and Wilson sandstone unconformably overlies the Hamlet formation along the Clatsop-Columbia county line where the Cowlitz Formation is approximately 200 m thick. The Cowlitz Formation appears to thin and pinch out to the west in the deep marine mudstone of the Sweet Home Creek member of the Hamlet formation in the western part of Clatsop County (Nelson,1985; Safley, 1988). Niem and Niem (1985) considered the Cowlitz Formation to unconformably overlie the Sweet Home Creek member. Farr (1989) suggested 20 a conformable relationship in his study area where the Cowlitz Formation and the Hamlet formation have similar structural attitudes and similar composition. The contact between the Cowlitz Formation and the overlying Keasey Formation has been interpreted variously as conformable, disconformable, and angularly unconformable. In the subsurface in the Mist gas field, the contact has been described as unconformable. Since the contact in the subsurface can not be located on the basis of the lithology of well cuttings, this interpretation is based on the abrupt changes from Narizian to Refugian microfauna between the Cowlitz and the Keasey, as well as the irregularity of the base of the Keasey Formation as shown by seismic reflection data (Jack Meyer, personal communication, 1989). This paleontological criterion does not agree with The North American Code of Stratigraphic Nomenclature which defines "formation" in article 24 as a rock body, identified by lithic characteristics and stratigraphic position, which is prevailingly but not necessarily tabular and is mappable at the earth's surface and traceable in the subsurface. An interf ingering relationship has been suggested by Jack Meyer (personal communication, 1989) based on core descriptions, and by mud and geophysical logs. Farr (1989), in his field area about 12 kilometers south of the Mist field described a conformable to slightly conformable relationship between the Keasey and the Cowlitz outcrops based on the lithology. In 21 this area, the arkosic sandstone at the top of the Cowlitz Formation is differentiated from the basaltic and glauconitic sandstone at the base of the Keasey Formation. The composition change appears to be gradational. Timmons (1981), also observed a gradational contact over a thickness of 40 meters, grading from fine grained arkosic sandstone of the upper Cowlitz to glauconitic and tuffaceous mudstone and siltstone of the lower Keasey Formation. Seismic reflection data have been interpreted as showing an angular unconformity (Jack Meyer, personal communication, 1989). Depositional Environment The depositional environment of the Cowlitz Formation has been the subject of several interpretations, especially for the Clark and Wilson sandstone, which is the reservoir unit of the Mist gas area. Van Atta (1971) suggested that the sediments were deposited in a near-shore marine and a high energy environment. A bathyal deep channel model was postulated by Bruer (1980}, analogous to the deep water sands of the modern Strait of Juan de Fuca in northwestern Washington, with the sand deposited in deep water between volcanic highs in a narrow channel. These sands were later reworked by strong currents (Olmstead, 1985). Timmons (1981} suggested a near shore, wave dominated, energetic and open marine environment. A marine transgression may have formed sheet sand deposits (Farr, 1989}. McKeel (1980) 22 conducted a paleontological study on the Texaco Cooper Mountain #1 well in the south Tualatin basin (see figure 1 for location), and concluded that the Narizian environment was an open marine and near shore environment, and identified two transgressions in the lower Narizian. These marine transgressions would have also resulted in the transgression of nearshore sand deposits (Shaw, 1986). Shaw (1986) suggested an upper bathyal model for the upper Cowlitz sand which is in conformity with the water-depth determination of outer neritic depth, or bathyal depth. Jackson (1981) interpreted the depositional environment as near shore marine to brackish water. Alger (1985) interprets the sand as nearshore, predominately shallow water shelf. The most recent work has been done by Farr (1989), who concluded a deltaic depositional environment. The deposition of the Cowlitz Formation ended abruptly with very active tectonism and erosion (Timmons, 1981). KEASEY FORMATION The Keasey Formation consists of a dark to medium gray siltstone and massive tuffaceous gray mudstone (Van Atta, 1971). It is exposed at the surface in southeast Clatsop, and through much of Columbia, Tillamook and Washington counties. In the upper Nehalem River basin, Warren and Norbisrath (1946) divided the Keasey Formation into lower, middle, and 23 upper members. The lower member consists of dark shale, the thickness and composition of which vary from place to place. The best exposure is on Rock Creek. The middle member is composed of light gray, unstratified, tuffaceous siltstone, with some hard calcareous beds. It is best exposed along Rock Creek and in the bank and hillside along the Nehalem River. The upper member consists of from 100 to 200 feet of interbedded claystone, tuffaceous siltstone, and tuff bands. The upper member is best exposed in Washington County and near the town of Vernonia. Primary structures in the Keasey include cross lamination, ripple lamination, and bioturbation features. The Keasay Formation was deposited in an upper slope environment, this interpretation is based on microfauna and lithology (Rarey, 1986; Farr, 1989). The provenance of the Keasey Formation includes basaltic volcanics to the southwest, rhyolitic and andesitic volcanics from the Cascade Mountains and central Oregon to the east, and silicic and intermediate igneous plutonic rocks and metamorphic rocks of the Rocky Mountains region to the northeast (Van Atta, 1971). Based on micro and megafauna, the age of the Keasey Formation is considered to be Refugian (late Eocene to middle Oligocene) (Van Atta, 1971). Late Narizian foraminifera have been reported in the Keasey, but this could be a product of reworking of the Cowlitz sediments 24 during the deposition of the Keasey (Jack Meyer, personal communication, 1989). Bruer and others (1984) restricted the Keasey Formation to Refugian. The contact relationship between the Keasey Formation and the underlying Cowlitz Formation has been discussed above. The distinct lack of mica and the abundance of volcanic detritus in the Keasey sediments help to identify the contact between these two units in outcrops. However, in drill cuttings the identification is more difficult. The Keasey Formation is overlain disconformably by the Pittsburg Bluff Formation (Warren and Norbisrath, 1946). Van Atta (1971) in his study area on the upper Nehalem River basin reported an apparent conformity between these two units. THE JEWELL MEMBER OF THE KEASEY FORMATION The Jewell member of the Keasey Formation consists of a sequence of laminated to thinly bedded, locally glauconitic mudstone. This name was informally proposed by Olbinski (1983) for the type locality near Jewell in Clatsop County, and followed by Nelson (1985) in the Jewell-Fishhawk Falls area, Oregon. This unit is correlative to the lower and· middle part of the type Keasey Formation in Columbia County, and to the Narizian upper mudstone member of the Cowlitz Formation of Bruer and others (1984) in Clatsop and Columbia counties. The lithology of the Jewell member is similar to 25 the lower two members of the Keasey Formation, but tends to be thinner, better laminated, darker colored, and contains elastic dikes (Rarey 1986). The petrographic analysis done by Rarey (1986) indicates igneous, metamorphic and sedimentary sources, while the presence of andesitic and basaltic fragments suggests an andesitic and basaltic source which could have been produced by the developing Cascade arc to the east. The northern cascades of Washington, the Klamath terrane of southern Oregon and Northern California, and the Idaho and Wallowa batholiths are probable sources for the metamorphic and silicic igneous rocks (Rarey, 1986). PITTSBURG BLUFF FORMATION The Pittsburg Bluff Formation consists of a lower fine grained sandstone containing numerous fossils, concentrated in layers and in calcareous concretions, which grades upward to a coarser, massive sandstone and interfingers with tuffaceous beds. The type locality is near Pittsburg, Oregon, along the Nehalem River. Here, the Pittsburg Bluff Formation consists of massive, fine grained arkosic to lithic arkosic clayey, tuffaceous concretionary sandstone beds, containing fossil mollusk, wood and some coaly material. The Pittsburg Bluff Formation in the upper Nehalem River basin is partly marine and partly brackish water in origin. Deltaic deposits seem to interfinger with 26 a near-shore fossiliferous marine beds (Warren and Norbisrath, 1946). In the western Tualatin Valley, Thoms and others (1983) described two members in the Pittsburg Bluff Formation as having as volcaniclastic member and a siltstone member. The volcaniclastic member consists of volcanic litharenite and volcanic conglomerates (200 feet thick), for which the provenance is a local volcanic center. The siltstone member is composed of muddy siltstone with minor interbedded coarse to very fine-grained tuffaceous, micaceous sandstone, deposited in a shallow, neritic {upper shelf) to very near marine environment. The age of the Pittsburg Bluff Formation is considered to be mostly middle Oligocene, included in the upper part of the Refugian stage and partially correlative with the upper Eocene to middle oligocene Eugene Formation of the southern Willamette Valley and the Central Coast Range (Van Atta, 1971). The Pittsburg Bluff Formation is overlain by the Scappoose Formation with an apparent unconformity. It disconformably overlies the Keasey Formation in Columbia County and the Sager Creek Formation in Clatsop County. (Warren and Norbisrath, 1946; Van Atta, 1971; Niem and others, 1985). 27 SCAPPOOSE FORMATION The name Scappoose Formation was proposed by Warren and Norbisrath (1946) for the tuffaceous sandstone and shales overlying the Pittsburg Bluff Formation and capped by the Columbia River basalt. It is best exposed in an outcrop within the drainage basin of the upper Nehalem River basin, where Warren and Norbisrath (1946) estimated a thickness of 1500 feet. The compositions of the Scappoose Formation and the Pittsburg Bluff Formation are similar but the fauna are different. Therefore, they can be distinguished by their fossil contents (Warren and Norbisrath, 1946) . The provenance is a combination of granitic plutons and volcanics. Nonmarine and marine lithofacies have been described by Van Atta and Kelty (1985) in Columbia County. The nonmarine lithofacies is characterized by a basal bed consisting of poorly-sorted, framework-supported, pebble to boulder conglomerate, deposited in a nonmarine, deltaic fluvial environment. The marine siltstone lithofacies is a highly fossiliferous siltstone coarsening upward into, and laterally intertonguing with fluvial arkose. These sediments were deposited in a shallow neritic to estuarine environment. The Scappoose Formation is middle Miocene in age because it unconformably overlies both the Keasey and the Pittsburg Bluff formations and interfingers with the middle Miocene Yakima basalt, which is a subgroup of the 28 Columbia River Basalt Group (Van Atta and Kelty, 1985). The age of the Scappoose Formation was formerly thought to be late Oligocene or early Miocene (Warren and Norbisrath, 1946). Part of the Scappoose Formation may be correlative with or equivalent to the Astoria Formation in Clatsop County. COLUMBIA RIVER BASALT GROUP The Columbia River Basalt Group is composed of a sequence of individual flows of basaltic lava of various thickness, which generally rest directly one on another, but may be separated by pyroclastic material or waterlaid sediments. The Columbia River basalt flows cover an area of roughly 163,700 Km2 in Oregon, Washington and Idaho, with an estimated volume of approximately 174,300 Km3 (Tolan and others, 1989). Radiometric age determinations suggest that these flows were erupted during a period from 17 to 6 m.y. ago, with more than 99 percent by volume being erupted in a 3.5 m.y. span, from 17 to 13.5 m.y. ago. The duration of individual eruptions lasted from several days to as long as several weeks. Columbia River basalt flows were erupted from north-northwest trending fissures or linear vents in northeastern Oregon, eastern Washington and western Idaho (Tolan and Beeson, 1984). 29 SMUGGLER COVE FORMATION The Smuggler Cove formation consists of thick bedded, bioturbated, tuffaceous claystone and siltstone, with a few graded volcanic sandstone beds. It also contains tuff, elastic dikes, and glauconitic sandstone. This unit is present in Clatsop County and was informally called Oswald West mudstone by Cressy (1974). This usage was also followed by Niem and Van Atta (1973) and Well and others (1983). Rarey (1986) divided the Smuggler Cove formation into four informal units: lower member, a glauconitic sandstone member, upper member, and Ball park member. The lower member of the Smuggler Cove formation is composed of a basalt sequence of very well laminated, slightly micaceous, silty mudstone. This unit has been mapped over large areas where it varies in thickness from less than two to several meters (Rarey, 1986; Niem and Niem, 1983). The upper member consist of fossiliferous, bioturbated, tuffaceous, concretionary siltstone and siltstone at the base. The middle and the upper part of this member is composed of thick bedded, bioturbated silty mudstone and rare arkosic to lithic sandstone beds. The Ball park unit consists of well laminated, micaceous and carboniferous dark gray to greenish gray silty mudstone, and subordinate, thin, fine to medium-grained 30 arkosic sandstone. The age of the lower three members of the Smuggler Cove formation ranges from upper Eocene (Refugian stage) to Oligocene (Zemorrian stage} and the age of the Ball park has been confined to the Oligocene or lower Miocene. The lower member of the Smuggler Cove formation is correlative to the upper mudstone member of the Keasey Formation of Nelson (1985) and the Sager Creek formation of Niem and Niem (1983}. The glauconitic sandstone member and the upper member are correlative to the base of the Pittsburg Bluff Formation of eastern Clatsop County. In Columbia County, the Scappoose Formation is correlative to the upper portion of the Smuggler Cove formation (Niem and Niem, 1985). The depositional environment of the lower three members (lower member, glauconitic sandstone, upper member) was a fore arc basin, middle slope to outermost shelf. The Ball park unit may be deposited in an outer-shelf to upper slope channel. The Smuggler Cove formation conformably overlies the Jewell member of the Keasey Formation and is unconformably overlain by the Astoria Formation. SAGER CREEK FORMATION The Sager creek formation is well developed in eastern Clatsop County and thins and interfingers with the 31 tuf faceous lower Smuggler Cove formation in the west and southwest. This unit unconformably overlies the Keasey Formation (Niem and Niem, 1983). The Sager Creek formation consists of a thick sequence of well-laminated micaceous and carboniferous mudstone rhythmically interbedded with thin feldspathic sandstone. It was informally called the Vesper Church member of the Keasey Formation by Wells and others (1983) and Nelson (1985), in Clatsop County, and lower Pittsburg Bluff Formation by Warren and Norbisrath (1946) and Kadri (1982) in Columbia County. The depositional environment of the Sager Creek formation was a deep marine channel. ASTORIA FORMATION The lower to middle Miocene Astoria Formation unconformably overlies older rocks in the northern Oregon Coast Range (Newton, 1969). As described by Niem and others {1985), it consists of four members: The Angora Peak, Wickiup Mountain, Youngs Bay, and Cannon Beach members. The Angora Peak member consists of massive to laminated fine grained arkosic sandstone with subordinated trough, and planar cross bedded, coarse grained, volcanic sandstone; minor pumiceous-volcanic to polymict conglomerate and laminated carbonaceous mudstone with thin local subbituminous coal beds. This unit was deposited in a 32 shallow marine and fluvial environment (Rarey,1986; Nelson, 1978; Niem and Niem, 1985) The Wickup Mountain member unconformably overlies the Smuggler Cove formation. It is composed of structureless to laminated, fine-grained feldspathic, fossiliferous sandstone. Locally trough-cross-bedded structures are present. The upper part of the unit is a sequence of mudstone, siltstone, and very fine glauconite sandstone. The Wickup Mountain member was deposited in a shallow marine environment. The age of this unit is Miocene. The cannon Beach member is composed of upper and lower mudstone units. The lower mudstone consists of well stratified, rhythmically interbedded, fine grained, micaceous, carbonaceous sandstone and dark gray mudstone. The upper mudstone consists of well laminated, locally highly carbonaceous and micaceous, dark gray mudstones. Both upper and lower mudstones were deposited in a deep marine environment (Nelson, 1978; Niem and Niem, 1985) The Youngs Bay member consists of very thickly bedded medium to coarse grained, structureless, friable, arkosic sandstone bodies intertonguing with mudstone. The thickness of the sandstone ranges from approximately 65 to 340 meters (Nelson, 1974; Niem and Niem, 1985). TROUTDALE FORMATION The Troutdale Formation consists of fluvial siltstone, 33 sandstone, and conglomerates, found throughout much of northwestern Oregon. Two lithologic facies have been defined: The first facies is characterized by conglomerates that contain such deposits of an ancestral Columbia River as quartzite, schist, granite, and rhyolite. They are found in proximity to the modern Columbia River and are confined to the northern portion of the Willamette Valley. The other facies is characterized by conglomerates having clasts locally derived from the Cascades and transported by streams into the Willamette lowland (Tolan and Beeson, 1984). BIOSTRATIGRAPHY Foraminiferal stages are used here to define the biostratigraphy of northwestern Oregon. McKeel (1983-1984) used the California benthic foraminiferal stages of Kleinpell (1938), Schenck and Kleinpell (1936), and Mallory (1959), in comparison with the biostratigraphy of the northern Willamatte basin. Based on rare but distinctive planktonic foraminiferal occurrences, strata recognized herein as Refugian, Narizian and upper Ulatisian, they represent the following regional stages: Uppermost Refugian = Early Oligocene Rest of Refugian = Late Eocene Upper Narizian = Late Eocene Lower Narizian = Late Middle Eocene Upper Ulatisian = Early Middle Eocene (McKeel, 1983,1984). The oldest foraminif era stage observered at Mist may belong to the Ulatisian stage. The upper Narizian stage is represented within the basal conglomerate and mudstone underlying the Cowlitz Formation (Yamhill-informal Hamlet formation) and continues upward to the top of the Cowlitz section and part of the Keasey (Olmstead, 1985). The upper Narizian sediments are marked by the benthic foraminifera Cibicides natlandi and/or Bulimina microcostata and by the 35 planktonic foraminifera Globigerinatheka index and Pseudohastigerina micra. Refugian stage foraminiferas are found in the Keasey Formation. The highest occurrence of the benthic foraminif era Uvigerina cocoaensis and Cassidulina galvinesis and the planktonic foraminifera Turborotalia Insolita mark the Refugian stage. The biostratigraphic correlation relied on the detailed micropaleontological work of Daniel McKeel, and James Moore. Two core samples (AlO and All) from the Columbia County IW 220-10 well were analyzed. Sample AlO contain megafossil fragments which could not be identified. Sample AlO contains the benthic foraminifera Bulimina microcostata which is a Narizian indicator. The biostratigraphic contact in this well could not be determinated since only a Narizian fauna was identified from the samples. Figure 4 shows the biostratigraphy of the lower Refugian and upper Narizian as well as depth of contact. In the Crown Zellerbach # 30-33, Crown Zellerbach #2 and Texaco Cooper Mountain #1 wells the contact depth has been estimated since the paleontological information is undetermined. 36 / , , / . ) WELL A B c D E F G l1 J L Cr~)Wn Crown Texaco NAME Patton Clatsop Co. Columbia Co. IW-220-10 Columbia Co. Columbia Co. Longview Fiber Zel Je~bach Zellerbach Cooper No. 32-9 No. 33-11 No. 31-8 No. 32-10 No. 1 No. 25-33 .. No. -30-33 No. 2 Mountain 690-lOSQ ft 'l"..J.dX>rotalia insoli ta Uvigerina o:x::oaensi.:; Tud:orot-..alia ins:>J. ita Uv±geri.na atwilli 'nrt:orotalia insolita Unider\tified mega Bolivi.na cf orogonen- Uvigerina cf atwilli caucasina schenki c. Tl.lrb::>rotalia insolit.i t.Jri.9er ina atw'tlli fo&Sil fra<;nents sis . Upper N upper I ,. oi2gnosti~ I l I I .I ,\ I 690 - 1(150 ?? ft 1960 ?? ft 3316 ?? ft Oepth Contact 7250 ft 3610 ft 2170 ft 2000 ft 590 ft 1620 ft 590 ft R. "ih:m!:: Jrunes D. M:>cre, 19Rl McKee!, 19!33 Mc.l(eel, 1983 r-ti Fi.gura 3 . Biostra ·tigraphy of fourtee n wells drilled in northw E:stern Oregon showing the cent act between t jle Refu gian and Narizian Stages. ANALYTICAL PROCEDURES GEOCHEMISTRY Instrumental Neutron Activation Analysis Instrumental Neutron Activation Analysis (INAA) is a technique for determining qualitative and quantitative elementary composition. The procedure of INAA is based on the irradiation of samples in a nuclear reactor with a neutron flux, resulting in the production of radioactive isotopes which emit gamma and beta radiations as they decay to stable nuclei. The radiation is characteristic of the isotope concerned and the intensity of the radiation is a measure of the isotopes abundance and hence of the initial elemental abundance. Each radioactive nuclide has its own characteristic energy and half life. Comparative measurements of sample radioactivity are calculated with a similarly irradiated standard containing a known amount of elements. Two approaches may be used to evaluate induced radioactivity: a) radiochemical separation followed by counting the separated activities, and b) instrumental gamma spectrometry. The instrumental method was used in this research. The various radioisotopes formed in a sample can be identified by a device called a gamma ray spectrometer, which consists of gamma ray detector, a pulse height analyzer, and read out device (computer). The gamma ray 38 spectrometer measures the energies and intensities of various gamma rays emanating from an activated sample. Following irradation, the samples are allowed to decay (cool) to permit unwanted short-lived activity to diminish and are then counted. The first count is done 3-5 days and a second 15-20 days after irradiation. Sampling Drill cuttings from six wells: Columbia county # 31-8, IW 22D-10, Crown Zellerbach #30-33, Longview Fibre #25-33, Crown Zellerbach #2 and GPE. Federal Com. #1 (see figure 1 for location) were selected to be analyzed chemically using the INAA method. The objective was to find a distinct change in the trace element concentrations between the Keasey and the Cowlitz formations. The cuttings were provided by the Oregon Department of Geology and Mineral Industries (DOGAMI) and Oregon Natural Gas Development Corporation (a subsidiary of Nothwest Natural Gas Company). Most of the wells are located in the Mist gas field (Columbia County), which is located on the east flank of the northern Coast Range gravity high (Bromery and Snavely, 1964) corresponding to the Nehalem arch of Armentrout and Suek (1985) (Figure 4). This arch separates the Astoria basin on the west from the northern Willamette basin to the east. The Columbia county 31-8 well is located off the arch toward the Astoria basin and the GPE Federal Com. #1 well 39 N t C MILES 20 MGALS C KILOMETERS 30 ' n > 30 a' -30 TO 0 L..:J OTO 30 [I <-30 D Figure 4. Regional Bouguer gravity anomaly map for northwest Oregon and southwest Washington showing the location of the Mist gas field on the east flank of the northern Coast Range gravity high. (From Suek, 1982.) 40 is located to the south of Mist gas field. The Cutting interval in Columbia County 31-8 and G.P.E. Federal Com. #1 wells is 10 feet, while the rest of the wells have a cutting coverage of 30 feet. The samples were collected at various depths where the contact between the Refugian and Narizian stages exists, as well as the lithological contact between the Keasey and the Cowlitz formations. Basalt chips were collected from the GPE Federal Com. #1 in the following intervals: 3260-70 , 3430- 50, 9700-20, 9950-70 feet. Sample Preparation One of the advantages of the INAA method is that sample preparation is minimal. Approximately 3-5 grams of sample were placed in a 40 ml beaker with distilled water for a few days in order to see if there were oil remains from the drilling mud. After being washed, decanted, and oven dried at a temperature of 50°C the samples were crushed, sieved through a 200 mesh screen, and split to one gram, and then placed in clean 1/2 dram polyvials and heat sealed to prevent leakage. Steel contaminants (drill bit chips) were removed from the samples with a magnet to avoid error in the concentration of Fe. The samples were irradiated at 250 KW for one hour at the Reed College nuclear reactor. Gamma ray spectra were first obtained by counting five days after irradiation. A second count was done 18-22 days after 41 irradiation. Elemental abundances and errors were calculated by comparison to the U.S.G.S. standard GPS-1 and National Bureau of Standards Coal Fly Ash, SRM 1633a. Two different detectors were used in this research to count the samples. Second count of samples: GPE 15 to GPE 33 from the GPE Federal Com. #1 and all the samples from Crown Zellerbach #2 were counted using the (High-Purity Germanium) coaxial Photon Detector System, GE&G ORTEC. The rest of the samples were counted in the Ge(Li) detector & Tracor Northern TN 4000. This was necessary because of the failure of the Ge(Li) detector. GEOCHEMICAL DATA AND DISCUSSION Concentrations of the elements in the samples from each well are listed in Tables I, II, III, IV, v, VI and VII. Calculated Sc/Co ratios are shown in table VIII. Plots of K, Rb Th and Sc/Co ratio vs depth are represented in figures 5,6,7,8,10 and 11. Thorium (Th), potassium (K), rubidium (Rb) and scandium (Sc) appear to establish significant grouping as well as Sc/Co ratio. Four different groups of samples can be distinguished. one group is characterized by having high concentrations of K, Th and Rb and low Sc/Co, the second group by having low concentrations of K, Th and Rb and high Sc/Co, a third group with a significant lower value of Rb and high Sc, and a fourth group where the concentrations of 42 these four elements do not show any particular pattern. Previous geochemical work done by Kadri (1982) in outcrop samples from Tertiary rocks revealed that the Cowlitz Formation has higher concentrations of K and Th than does the Keasey Formation. The high concentrations of K, Th, and Rb in the Cowlitz Formation are expected since the provenance of this formation is igneous and metamorphic rocks of the craton and these elements are highly concentrated in them. This relation appears also to be constant in drilling cuts, even though some contamination during drilling could occur. Samples with high basaltic volcanic influence tend to have very low Rb values and high Sc. Data from the Columbia County IW 22D-10 and Longview Fiber #25-33 wells (Tables I and II) show two groups (Keasey and Cowlitz formations). A distinct break between the higher and lower concentration of these elements determine the geochemical contact between the Keasey and Cowlitz formations in these particular wells. Figures 5 and 6 show the plots of K, Th, Rb and Sc/Co vs depth. The change between the two formations'chemistry group in the Columbia County IW 22d-10 well occurs at approximate 2,000 feet depth and in the Longview Fiber #25-33 well at 600 feet depth. Samples from Crown Zellerbach #30-33 (Table III) show only concentrations characteristic of the Cowlitz Formation 'rABLE I GEOCHEMISTRY OREGON NATURAL GAS IW-22d-10 Sample # Depth (ft) Na K Rb Ce Eu Th IW 1 720 1.36 .01 0.56 0.19 32.0 9.0 23.7 1.0 0.88 .04 2.34 .13 IW 13 1590 1.86 .01 0.96 0.18 41.0 7.0 27.6 0.9 0.96 .04 3.02 .15 IW 14 1680 1.82 .01 1.18 0.15 24.0 6.0 28.3 0.9 0.99 .04 3.18 .13 IW 15 1800 1.82 .01 0.90 0.14 28.0 6.0 32.6 0.9 1.04 .04 4 .11 .14 IW 2 1920 1.86 .01 0.98 0.19 37.0 7.0 34.0 1.1 1.19 .04 4.26 .15 IW 3 1950 1. 79 .01 1.03 0.18 35.0 9.0 37.6 1.1 1. 24 .04 4 .13 .17 IW 4 1980 1.89 .01 0.93 0.18 41.0 9.0 52.5 1.1 1.92 .04 4.14 .17 IW 5 2040 1.46 .01 1.56 0.19 71.0 9.0 47.0 1.1 1.30 .06 6.45 .18 IW 6 2070 1.34 .01 1.71 0.19 79.0 7.0 51.9 1.2 1.36 .04 7.48 .19 IW 7 2100 1.39 .01 2.0 0.2 101.0 8.0 55.1 1.3 1. 45 .08 7.41 .18 IW 8 2200 1.09 .01 2.02 0.16 76.0 4.0 48.9 0.7 1.13 .03 6. 75 .12 IW 9 2310 0.94 .01 5.7 1.9 162.0 8.0 23.6 0.7 1.04 .04 3.69 .11 IW 12 2520 2.05 .01 1.2 0.2 57.0 9.0 62.2 1.2 2.55 .05 2.95 .18 IW 10 2700 1.03 .01 2.8 0.2 80.0 7.0 83.8 1.0 1. 72 .04 8.73 .15 IW 11 2770 1.45 .01 3.8 0.2 96.0 6.0 52.3 0.9 1.13 .03. 7.91 .14 Note: Na, K and Fe in percent oxide Trace elements in ..i:: w TABI,E I GEOCHEMISTRY OREGON NATURAL GAS IW-220-10 (continued) Sample # Depth (ft) Hf Fe Sc Co Ll\ Sm IW 1 720 2.51 .17 4.65 .05 16.85 .11 7.8 .3 11.4 .4 3.0 .03 IW 13 1590 3.35 .17 3.85 .04 15.96 .09 8.4 .3 13.8 .4 4.06 .05 Hi' 14 1680 3.30 • 17 3.65 .04 16.12 .09 8.6 .3 13.7 .4 3.57 .04 IW 15 1800 3.58 .13 4.29 .04 17.25 .10 9.2 .3 16.8 .4 4.02 .04 IW 2 1920 3.9 .2 4.58 .05 17.93 .11 10.6 .4 15.7 .5 4.07 .04 IW 3 1950 3.38 .19 4.61 .05 18.94 .12 11. l .4 19.1 .5 4.17 .04 IW 4 1980 3.7 .2 4.34 .05 17.19 .11 9.6 .3 22.7 .5 7 .11 .05 IW 5 2040 3.52 .19 4.86 .05 17.25 .11 11.2 .4 23.3 .5 5.27 .05 IW 6 2070 3.55 .19 4.89 .05 17.23 .11 12.1 .4 24.9 .5 5.28 .04 IW 7 2100 4.1 .2 4.92 .06 18.62 .12 12.9 .4 27.1 .5 5.94 .05 IW 8 2200 4.97 .13 2.05 .OJ 6.03 .05 5.6 .2 30.J .4 4.46 .OJ IW 9 2310 1.87 .11 3.65 .05 4.22 .04 6.2 • 2' 12.4 .3 2.51 .04 IW 12 2520 5.3 .2 8.7 .08 24.02 1.4 31. 7 .8 29.8 .5 7.70 .05 IW 10 2700 4.17 .16 3.63 .04 8.17 .06 8.6 .4 43.5 .4 • 7 .54 .05 IW 11 2770 5.10 .16 4.82 .05 5.30 .05 14.9 .4 27.1 .4 5.17 .05 Note: Na, K and in petx!ent oxide Trace elements in ppm +: -r:- Oregon Nuturo1 Gas IW - 220 - 10 Sc /Co (ppm) K (S) Rb(ppnt) Th (ppm) 0 0 500 500 1000 1000 .. -..... -...c 1500 1500 CL Cl.I Q 2000 2000 2500 j 2500 3000 1 1 1•1•1•1•1•1 • i3ooo ,._, 0 •, 1.,.,.,.1.,.,.~ a> co 0 II,) (N 0 Concentration figure 5. Variation of elements concentrations with depth. IW-22d-10 + (J1 TABLE II GEOCHEMISTRY AMERICAN QUASAR PETROLEUM CORP. LONGVIEW FIBER f25-JJ Sample II Depth (ft) Na K Rb Ce Eu 1'H LF 1 500 1.69 .01 0.80 .15 28.0 6. J4.0 0.9 1.25 .04 2.12 .15 LF 2 590 1.89 .01 1.69 .17 69.0 a. 54 .o 1.0 1. JO .04 7.8J .16 LF 3 680 1.41 .01 1.67 .17 68.0 7. 43.8 1.1 1.20 .04 5.71 . n LF 4 800 l. 74 .01 0.95 • 15 98.0 7. 54.3 1.1 1. 33 .04 9.15 .17 LF 5 890 1.04 .01 1.43 .14 56.0 9. 49.0 1. 0 1. JO .04 6.52 • l :,i'" LF 6 980 1. J4 .01 1. 01 .14 40.0 8. 47.0 1. 0 1. 29 .04 5.90 . l'"' LF 1 1070 1.27 .01 1.52 .16 70.0 7. 53.5 1.0 1. 30 .04 7.52 .n Hf Fe Sc Co La Sm LF 1 500 3.60 .17 4.23 .04 17.02 .09 10.4 .3 16.9 .4 4.39 .04 LF 2 590 4.88 .17 4.27 .04 15.69 .09 11. 3 . 4 27.1 .4 5.90 • 0'":.> LF 3 680 3.45 .18 4.70 .05 17.45 .10 13.5 .4 23.7 .7 5.01 .04 LF 4 800 3.J6 .18 4.J8 .04 17.40 .10 12.1 .4 68.l .4 10.86 .06 LF 5 890 J. 58 .18 5.37 .05 18.J6 .10 12.8 .4 23.2 .4 5.02 .04 LF 6 980 3.73 .16 4.66 .04 17.08 .10 12.6 .4 2J.l .4 5.0J .04 LF 1 1070 3.99 .18 4.93 .05 17.07 .60 12.7 .4 26.6 • 4 • 5.30 .03 Na, K and Fe in percent oxide Trace elements in en Amer-icon Quasar Petroleum Corp .. Longview Fiber- •25-33_ Sc/Ce (ppm) K ('5) Rh (ppm) Th (ppm) 400 --r ------.----·------~ 400 500 1i'-- a ...._ .P 500 ~--·// 600 600 ~i(/ / // r;f ._ 700 1 700 - '~ \ -...,s::. ", '\ '-, c. 800 ;a 800 CD ,,- 0 900 '900 1000 r 1000 ~ ~ 1100 I ' I ' I ' I ' I • I • I • I • I • I •-..,. ·· f --T.....,.-r· ..,-.,- I • I • + 1100 0 t-) .,\\. a> N .,,. 0\ 00 0 0 g; 0 i:o b i-.> :,,. a. ~) ;_.~ :,,. Ul a. :..., Concentration Figure 6. Variation of elements concentrations with depth. Longview Fiber #25-33 + -...] TABLE III GEOCHEMISTRY AMERICAN QUASAR PETROLEUM CORP. CROWN ZELLERBACH #30-33 Sample # Depth (ft) Na K Rb Cc Eu TH CZ 1 1350 1.38 .01 l. 38 .13 54.0 7. 46.0 1.0 1.06 .07 5.98 .14 CZ 2 1440 1.19 .01 1.26 .13 48.0 9. 57.0 1.0 1.18 .04 8.64 • l'I CZ 3 1530 1.19 .01 l.ll .12 50.0 s. 59.2 1.0 1.19 .04 8.48 .16 CZ 4 1620 l.67 .01 0.90 .14 21.0 8. 125.0 1. 3 2.15 .05 11. 34 .18 CZ 5 1770 1.25 .01 1.46 .14 68.0 8. 49.5 0.9 1.22 • 04 6.52 • Hi Hf Fe Sc Co La Sm CZ l 1350 4.16 .15 4.52 .04 15.77 .07 11.4 .4 22.6 .4 4.80 .04 CZ 2 1440 4.35 .18 4.84 .05 16.45 .09 9.3 .3 28.5 .4 6.14 .05 CZ 3 1530 4 .14 .16 4.99 .05 16.38 .09 9.5 .3 29.7 .7 6.54 • 04 CZ 4 1620 10.2 .20 5.52 .05 13.00 .08 9.8 • 3 65.5 .4 10.45 .06 CZ 5 1770 3.85 .17 5. 41 .05 14.66 .08 13.6 . 4 24.3 .4 5.33 .05 Note: Na, K and Fe in percent oxide Trace elements in ppm + co Americon Quasor Petroleum Corp. Crown Zel1erboch #30-33 K(S) RB (ppna) Th (ppm) 1400 1400 =-1500 1 / 1 \ 1 I i I t- 1500 ~ -.-.c ~ ~ ~ ~ 1600 / / ~ ,/' ~·1600 ·""·.., 1700 .., 1700 i I ~l ~ 1800 ...... 0 t.,) (>~ ... 01 IJ't 01 IJ't ...... 00 :...- (if 0 0 0 0 0 0 b t..> '.llo. "' b N ~ Co '° °' Concentration Figure 7. Variation of elements concentrations with depth. Crown Zellerbach #30-33 +:" (!) 50 (Figure 7) indicating that the contact between the Keasey andthe Cowlitz formations is above 1,300 feet depth, which was the highest depth from which the samples were collected. Three geochemical groups are represented in well GPE Federal Com #1 (Table IV). The upper 3,000 feet have Rb, Th and Sc/Co values representing the Keasey Formation, but with much higher concentration of K. This interval is a silty, marine mudstone rich in glauconite, organic material and volcanic fragments. The high K could be due to the glauconite, below this depth Rb has decreased significantly and Sc increases showing a basaltic volcanic influence. This group is probably associated with local lava flows assigned to the Goble Volcanics or Tillamook Volcanics, which also display low Rb and high Sc. At 9,900 feet K, Rb and Th increase to values belonging to the Cowlitz Formation. Figure 8 shows the two distinct breaks between each formation. The concentration of Sc and Th in the basaltic chips (samples # GPE 20, GPE 21, GPE 23 and GPE 26) collected from the volcanic sediments, were plotted in a Sc vs Th graph (Figure 9) together with the Tillamook Volcanics, Eagle Creek Formation, Waverly Heights basalt and Skamania Volcanics. The purpose of the plot was to get an estimate of the tectonic environment of these basalts by comparing them with the others samples of known environment and to investigate possible sources for the associated sediments. TABLE IV GEOCHEMISTRY EXXON COMPANY - USA G.P.E. FEDERAL COMP. #1 sample I Depth (ft) Na K Rb Ce Eu Th GPE 15 1000 1.98 .01 1.90 .20 69.0 12.6 56.70 .11 1.61 .11 8.18 .25 GPE 16 1500 1.89 .01 .80 .20 55.7 18.0 J4.64 .90 1.66 .13 J.56 .26 GPE Jl 2200 1.25 .01 J.30 .30 51.0 12.8 o.oo .oo l.J4 .09 o.oo .oo GPE 17 2500 1.5 .01 3.10 .30 59.l 24.9 J6.24 .90 1.48 .09 J. 76 .25 GPE 18 JOOO 2.J6 .01 3.40 .30 49.0 14.5 32.2J .95 1.85 .13 2.36 .20 GPE 19 3200 1.59 .01 2.50 .20 o.o o.o 42.26 .95 2.00 .28 4.03 .14 GPE 20 J260/70 2.47 .01 1.80 .20 o.o 0.0 46.58 1.0 2.5 .14 2.67 .29 GPE 21 34J0/50 2.67 .01 2.JO .30 47.0 19.l 53.09 1.0 2.63 .14 2.44 .22 GPE 22 3500 1.64 .01 3.20 .30 o.o o.o 39.0 .9 1.82 .14 2.53 .23 GPE 8 4100 2.54 .01 1.48 .18 o.o 0.0 J0.3 1.0 1. 31 .04 1.69 .17 GPE 9 4200 1.65 .01 2.55 .17 o.o o.o 30.5 1.0 1.40 .04 1.66 .16 GPE 10 4300 1.89 .01 2.03 .16 0.0 o.o 37.2 1.0 1.59 .04 1.50 .14 GPE 11 4400 2.14 .01 l.60 .16 o.o o.o 47.0 1.2 1.93 .05 2.71 .18 GPE 12 4500 1.55 .01 2.3J .18 o.o 0.0 34.5 1.3 1. 57 .05 1.57 .18 GPE lJ 4600 2.70 .01 1.13 .19 o.o o.o Jl.9 1.0 1.49 .04 1.67 .14 GPE 14 4700 2.62 .01 l.04 .16 o.o o.o 40.4 1.3 l. 78 .05 2.1 .2 GPE 1 7500 2.66 .01 2.60 .2 o.o o.o 28.9 1.0 1.29 .04 1.84 .14 GPE 2 7600 2.51 .01 1.8 .15 o.o o.o 29.5 1.0 l.37 .04 1.77 .13 GPE J 7700 2.29 .Ol 2.33 .17 o.o o.o 33.l .9 1.31 .04 2.22 .13 GPE 4 7800 2.22 .01 3.0 .2 o.o 0.0 35.6 1.0 1.46 .04 2.5 .2 GPE 5 7900 2.33 .01 l.55 .14 2.7 0.6 29.4 .9 1.26 .04 1.87 .15 GPE 6 8000 2.17 .01 l.9J .16 o.o o.o 25.5 1.0 1.18 .04 1.29 .14 GPE 7 8100 2.14 .01 1.56 .14 0.32 0.6 25.2 .9 1.33 .04 1.28 .lJ GPE 23 9700/20 1.48 .01 2.JO .20 105.8 16.5 57.5 1.0 1.69 .09 1.0 .2J GPE 24 9800 1.87 .01 l.lJ .19 4J.9 14.9 31.J 8.7 1.41 .10 o.o .oo GPE 25 9900 1.90 .01 2.40 .JO 98.2 17.2 50.8 1.0 1.69 .11 6.56 .30 GPE 25 9950/70 1.70 .01 1.40 .JO 75.4 24.9 45.18 1.2 1.44 .07 6.67 .38 GPE 27 10,000 1.80 .01 2.00 .20 72.7 10.3 J6.61 .7 1.31 .10 4.58 .21 GPE 28 10,500 1.61 .01 1.80 .20 83.J 13.9 46.9 .8 1.38 .08 7.44 .21 GPE 29 11,000 1.59 .oo 2.30 .JO 77.0 14.9 54.2 1.0 1.63 .10 6.85 .29 GPE JO 11.280 2.92 .01 1.40 .30 68.0 18.4 29.7 .9 1.56 .14 3.74 .20 Note: Na, K and Fe in percent oxide Trace elements in ppm (J1 I-' TABLE IV GEOCHEMISTRY EXXON COMPANYUSA G.P.E. FEDERAL COMP. #1 (continued) Sample # Depth (ft) Hf Fe Sc Co La Sm GPE 15 1000 6.59 .14 4.10 .03 17.68 .77 9.49 0.30 31.87 .84 6.16 .05 GPE 16 1500 4.34 .16 4.85 .04 21.SO .71 12.37 0.37 17.73 .49 4.81 .OS GPE 31 2200 4.13 .37 4.:n .03 21.72 .76 11. 55 0.29 17.29 .41 4.31 .04 GPE 17 2500 4.25 .14 5.24 .04 19.91 .64 13.57 0.38 19.91 .46 5.00 .05 GPE 18 3000 4.07 .16 5.82 .04 27.04 .93 17.59 0.49 21.07 .48 4.8S .OS GPE 19 3200 4.03 .14 6.41 .04 25.39 .77 24.04 o.s7 13.75 .41 5.39 .os GPE 20 3260/70 3.85 .15 6.73 .04 33. 77 1.1 35.41 0.81 23.28 .70 6.70 .os GPE 21 3430/50 3.59 .15 5.66 .04 25.45 .8S 18.41 0.47 26.S .45 6.80 .os GPE 22 3SOO 4.01 .14 6.17 • 04 25.74 .so 21.88 0.53 31.6 .S7 5.18 .05 GPE 8 4100 3.04 .18 6.75 .06 27.63 .14 27.7 0.7 13.8 .04 3.72 .04 GPE 9 4200 2.95 .15 6.18 .06 25.09 .12 22.9 0.6 15.4 .04 4.12 .04 GPE 10 4300 3.06 .19 6.71 .06 27.42 .13 24.4 0.6 17.2 .04 4.82 .04 GPE 11 4400 4.1 .2 8.47 .07 31.56 .15 24.0 0.6 22.6 .04 6.17 .os GPE 12 4500 3.4 .2 7.28 .06 29.25 .14 25.5 0.7 16.0 .04 4.61 .04 GPE 13 4600 3.26 .18 7.17 .06 27.34 .14 23.2 0.6 15.2 .04 4.53 .04 GPE 14 4700 3.8 .2 7.86 .07 34.04 .17 32.4 0.8 lS.4 .04 4.22 .04 GPE 1 7500 3.05 .16 6.0 .06 24. 71 .17 22.3 0.6 14.3 .04 3.63 .04 GPE 2 7600 3.2 .15 6.0 .06 23.61 .12 21.4 0.6 15.0 .04 4.05 .04 GPE 3 7700 3.85 .17 5.78 .05 22.69 .11 20.7 0.6 16.2 .04 4.14 .04 GPE 4 7800 3.73 .18 5.83 .05 23.04 .11 20.2 o.s 17.4 .04 4.53 .04 GPE 5 7900 3.31 .17 5.59 .05 22.33 .11 24.8 0.6 13.7 .03 3.96 .04 GPE 6 8000 2.48 .18 6.85 .06 24.92 .12 3S.O 0.8 11.1 .04 3.33 .04 GPE 7 8100 2.32 .17 6.79 .06 28.02 .14 31.2 o.s 12.0 .03 3.64 .03 GPE 23 9700/20 5.25 .16 5.63 .04 20.61 .65 20.82 0.52 22.01 .47 5.97 .05 GPE 24 9800 2.87 .27 5.49 .03 26.68 .80 25.05 0.57 24.40 .55 3.48 .04 GPE 25 9900 4.91 .16 5.36 .04 26.24 .87 19.90 0.51 18.89 .57 5.65 .05 GPE 26 9950/70 4.52 .22 S.86 .05 23.34 .76 23.18 O.S7 42.28 1.16 5.82 .06 GPE 27 10,000 3.68 .13 3.69 .03 15.90 .53 15.15 0.39 13.lS .32 4.08 .OS GPE 28 10,500 5.05 .13 J.97 .OJ 14.59 .49 11.88 0.33 19.63 .40 5.14 .05 GPE 29 11,000 5.21 .15 4.67 .03 17.18 .56 13.76 0.39 32.50 .79 6.24 .os GPE 30 11,280 3.36 .15 5.11 .04 22.47 .83 16.23 0.43 28.70 .74 4.59 .09 Note: Na, K and Fe in percent oxide Trace elements in ppm ()"1 N Exxon Compony - USA G.P.E. Federal Comp_ • 1 K (S) Rb (ppm) Th(ppm) Sc /Co (ppm) 0 I I 0 2000 -I ------I ( -:1...,.,.,..---. I '\._ I- 2000 ' j } 4000 -I m<.:::::::_- ill r Loo ~ .... - 6000 ...f -I ...f J I \ I- 6000 J:! -~ ' c. Q) Q 8000 -I ~ §_ -I e..s'"" I~ I- 8000 10000 10000 12000 I ' I ' I I I I I I • I I I I I I I I I I I I I I I ~I I I I ' I I I I I ' I I f 12000 I ' I .,.. I .,.. 0 I\) ~ 0 I\) ()'\ m 0 I\) ()'\ 00 0 0 - - ~ - - ~ 0 0 0 0 0 0 i:J>moiv ~~mo Concentrot ion Figure 8. Variation of elements concentrations with depth. G.P.E. Federal Com. #1 c.n w 45 3 BS 40 Bs= Waverly Heights basalt 35 SV= Skaman1a Volcanics " EG= Eagle Creek ,.....--.. E3o TV= Till 15 EC 10 5 2 J 4.TT••5•11re;111171111A1111~ 0 Th (ppm) Fi~ure9. Sc vs Th. Comparison of GPE. Federal Com. #1 basalts with basalts from other sources. (Tl +:' 55 The basaltic chips show two different groups: A group with relative low Th and high Sc (samples GPE 20 and GPE 21), and a second group with high Sc and moderate Th (samples GPE 23 and GPE 26). This can be interpreted as two different chemical types of flows erupted in this place. The samples from the GPE Federal Com. #1 well did not plot close to the others basalts and can be distinguished from them. The tectonic environment cannot be determined from these data alone. Note also that the Sc and Th numbers for GPE 20 and GPE 21 are grouped with those for the associated sediments. The Crown Zellerbach #2 well shows the Keasey and the volcanic groups (Table V). The geochemical break is evident at 2,900 feet (Figure 10). The lowest portion of the well as in GPE Federal Com. #1, could be related to local volcanism. These two well are relatively close at (2.6 miles), and these sediments could be related to the same volcanic event. Data from the Columbia County #31-8 well (Table VI) represent group four, where the concentrations of K, Th, Rb and Sc vary from high to low values throughout the well (Figure 11). This result could be attributed to reworking of sediments from the Keasey and Cowlitz formation along with local volcanics, deposited in this local system as an alluvial fan. This alluvial fan could be formed on a steep continental slope or by vertical displacement (normal fault). The mud log from this well describes breccias, TABLB V GEOCHEMISTRY REICHHOLD ENERGY CORP. CROWN ZELLERBACH 112 Sample II Depth (ft) Na K Rb Ce Eu Th CZ2 1 2770 1.73 .01 1. 40 .30 75.18 19.9 35.99 1. 04 1. 45 .06 3.33 .27 CZ2 2 2920 3.45 .02 1. 40 .JO 45.2 20.6 34.0 0.94 1. 711 .12 2.44 .21 CZ2 3 2980 3.37 .01 1.00 .30 o.o o.o 24.0 0.88 1.76 .11 2.66 .27 CZ2 4 3100 2.12 .01 0.90 .30 o.o o.o 22.15 0.97 1.5'/ .09 2.01 .20 CZ2 5 3220 2.65 .01 1. 70 .30 o.o o.o oo.oo o.oo 1.71 .11 o.oo .oo Hf Fe Sc Co La Sm CZ2 l 2770 4.80 .17 6.64 .05 22.74 1.5 15.42 .39 18.54 2.68 4.98 0.91 CZ2 2 2920 4.07 .15 5.78 • 04 26.63 1. 7 17.87 .45 17. 18 2.47 4.85 1. 39 CZ2 3 2980 3.85 • 31 5.85 .04 26.99 1.9 17.45 .44 16.60 2.66 4.82 2. 32 CZ2 4 3100 3.47 .17 6.67 .04 27.69 1.2 23.73 .58 16.60 2.66 4.49 0.96 CZ2 5 3220 3.25 .30 6.20 .04 17.73 1.1 25.19 .60 15.67 3.01 4.48 1. 00 Note: Na, K and Fe in percent oxide Trace elements in ppm (J1 m Reichhold Energy Corp. Crown Ze1Jerboch •2 K (~) Rb (ppm) Th (ppm) Sc/Ce(ppm) 2700 T --·---·-·- .. ------·---- 2700 p 2800 2800 2900. 2900 ..., -It- -.c 3000 3000 ..., Q. Cl) Q 3100 3100 / 3200 / 3200 33001 1 1 1 1•1 1 1 1 1 •I I I* I. I' I' I. I .1., .•. ,.,.,3300 0 .... _. - _. 0 A Cl' 0 IV (J1 -1 TABLE VI GEOCHEMISTRY ARCO OIL ANO GAS COMPANY COLUMBIA COUNTY #31-8 Sample I! Depth (ft) Na K Rb Ce Eu Th CC-Al 700 1.06 .oo 1.28 .11 86.0 12. 48.5 1.0 1.17 .04 5.7 .2 CC-A2 820 1. 52 .01 2.18 • 15 91.0 6 • 62.8 1.0 1.31 .04 9.44 .16 CC-A3 910 1. 71 .01 1.37 .14 66.0 7. 47.1 1.1 l. 38 .04 5.84 • HI CC-A4 1000 1.80 .01 o. 77 .14 38.0 7. 36.9 1.1 1. 28 .04 3.99 .18 ... CC-AS 1210 1.85 .01 0.75 .14 39.0 9. 37.5 1.1 1. 29 .04 4.28 .1 ) CC-A6 . 1420 l.82 .01 0.80 .14 33.0 9. 36.5 1.0 1.31 .04 4.39 .17 CC-A7 1510 0.84 . 00 0.00 .00 00.0 o. 16.0 0.8 0.51 .06 1. 78 .12 CC-AS 1600 1.68 .01 0.92 .14 41. 0 8. 30.9 1.0 1.04 .06 3.60 .16 CC-A9 2020 l. 74 .01 1.23 .16 39.0 9. 39.0 1.1 1.10 .05 5.38 .16 CC-AlO 2200 l. 77 • 01 1.02 .16 30.0 6 • 56.8 1.1 1.65 • 04 4.54 .16 CC-All 2440 1.94 .01 1. 40 .17 52.0 7. 36.5 1.0 1. 30 .07 3.26 .14 CC-Al2 2470 1.67 .01 2.16 .17 50.0 6. 43.2 1.0 1.50 .04 4.24 .15 CC-Al3 2500 2.00 .01 1.56 .17 29.0 6. 39.8 1.0 1. 36 .04 3.09 .13 CC-Al4 2560 2.14 .01 1.5 .20 34.0 7. 40.3 1.1 1.55 .04 3.47 .16 CC-Al5 2680 1.98 .01 1.98 .11 54. 0 6. 43.2 1.0 1.42 .06 3.13 .15 CC-A16 2740 1.94 • 01 1.63 .16 33.0 6 • 34.2 0.9 1.25 .05 2.52 .14 CC-Al7 2830 1.26 .01 0.85 .13 o.o o. 34.5 0.9 1.07 .06 2.03 .11 CC-Al8 2920 1.29 .01 2.10 .17 63.0 8. 50.3 1.1 1.41 .04 6.15 .15 CC-Al9 3010 1.80 .01 1. 7 .2 39.0 6. 38.7 1.0 1. 32 .04 3.61 .13 CC-A20 3100 1.58 .01 1.69 .17 33.0 7. 33.6 0.9 1.21 .04 2.98 .12 CC-A21 3820 1.29 .01 2.4 .2 90.0 8. 49.8 1.1 1. 24 .04 6.42 .18 CC-A22 3850 1. 81 .01 1.40 .18 36.0 .10. 59.7 1.1 2.10 .05 4.22 .15 CC-A23 3880 2.19 .01 0.55 .17 00.0 o. 69.8 1.1 2.59 .05 3.60 .17 Note: Na, K and Fe in percent oxide Trace elements in ppm (Tl OJ 'l'ABLE VI GEOCHEMIS'fHY ARCO OIL AND GAS COMPANY COLUMBIA COUNTY # 31-8 (continued) Sample # Depth (ft) Hf Fe Sc Co La Sm CC-Al 700 3.8 .2 17.67 .14 17.40 .11 4.8 .2 22.9 .4 4.71 • 0"3 CC-A2 820 4.74 .17 3.69 .04 13.73 .09 8.6 .3 31. l .4 5.66 .04 CC-A3 910 3.89 .19 4.45 .05 l!L 63 .12 11.1 . 4 20.6 .4 5.02 .04 CC-A4 1000 3.7 .2 4.44 .05 18.50 .12 8.8 .3 16.3 • 4 4.46 .04 CC-A5 1210 3.8 .2 4.82 .06 19.65 .12 9.9 .4 16.9 .4 4.49 .04 CC-A6 1420 4.04 .19 4.05 .05 17.58 .11 7.0 • 3 16.4 .4 4.43 .04 CC-A7 · 1510 1.52 .14 1.80 • 03 8.07 .07 5.1 .3 7.5 .3 1.87 .0) CC-AS 1600 3.12 .18 4.36 .05 18.61 .12 9.0 .3 14 .4 .4 3.69 .OJ CC-A9 2020 4.1 .2 4.56 .05 18.97 .12 10.3 .4 18. 6 .4 4 .33 .04 CC-AlO 2200 3.83 .18 3.92 .05 16.41 .10 8.0 .3 26.5 • 5 6.38 .04 CC-All 2440 4.09 .18 4.56 .05 17 .41 .11 12. 7 .o 17.4 .4 4.41 .o~ CC-Al2 2470 3.78 .18 4.76 .05 16.50 .10 13.0 .5 20.l .4 4.66 .05 CC-Al) 2500 l.46 .15 4.69 .05 26.46 .14 16.8 .o 19.l .4 4.68 .04 CC-Al4 2560 l.97 .19 4.98 .06 16.96 .11 15.9 .o 19.2 .4 4.86 .04 CC-Al5 2680 3.36 .15 4.90 .05 17.10 .11 16.l .5 21.2 .5 4.79 .04 CC-A16 2740 3.05 .14 5.73 .06 15.95 .10 17.8 .5 17.6 .4 4.02 .04 CC-A17 2830 2.26 .15 3.58 .04 12.06 .OB 11.4 .4 16.4 .4 3.85 .03 CC-Al8 2920 3.25 .18 4.88 .05 16.24 .10 14.4 .4 23.6 .5 5.28 .05 CC-Al9 3010 3.03 .15 4.66 .05 14.66 .09 14.4 .4 19.3 .4 . 4.44 .04 CC-A20 3100 2.77 .14 3.89 .04 13.74 .09 12.l .4 15.7 .4 3.92 .04 CC-A21 3820 4.32 .19 5.31 .06 15.70 .10 14.9 .5 24.9 .5 4.97 .04 CC-A22 3850 4.75 .19 7 .11 .07 20.01 .13 24.6 .7 29.l .5 6.74 .04 CC-A23 3880 5.2 .2 8.88 .oa 22.27 .13 33.0 .8 33.6 .5 8.02 . 0'> Note: Na, K and Fe in percent oxide Trace elements in ppm (J1 lO Arco Oi 1 ond Gos Company Columbio County •31-0 K(S) RB(ppm) 'TH(ppm) SC/CO(ppm) o~~~~~~~~~-..-~--~~~~~~-..~~~~~~~~~r---~~· 0 1000 1000 ~ -~ -.c 2000 2000 ~ Q. CD Q 3000 L 3000 ~ I I I I I I ~I I 4000 I • I I .,.I I I I I • .,.I I I ·+ f\) (1' .,.T 4000 0 to,) 0 to,) ti'\ CD 0 to,) ti'\ 00 0 0 0 0 0 Concentrot ion Figure 11. Variation of elements concentrations with depth. Columbia County #31-8 m 0 61 angular and rounded grains, granitic and metamorphic minerals, and volcanic fragments, indicating that it could be a mixture of sediments from the Keasey and the Cowlitz formations. A third possibility is that these are sediments are from a different source. The last possibility could be interfingering of the Keasey Formation with the Cowlitz Formation. This could be due to the intermittent deposition of both formations during the formation of the Western Cascades and uplift of the arch. The geochemical break between Keasey and the underlying reworked sediments is placed at 2,400 feet where the K shows a small increase. The influence of local basaltic volcanics in each area is indicated by the high concentration of Sc in the sediments. Figure 12 shows the plot of Sc vs depth for each well. The GPE Federal Com. #1 well has the most influx of volcanics among the wells. Geochemistry from the core samples (Table VII) collected from the Keasey and the Cowlitz formation in the Columbia County IW-220-10 well also shows the concentrations of the elements close to the drill cuttings. Some values of the Keasey Formation are higher in the core than in the drilling cut, but this may be due to the conglomeritic texture of the sample. Descriptions of the samples are in the Appendix. (A) Sc(ppm) (8) Sc (ppm) (C) Sc (f111m) 0 -I-----,---- 0 -t-·..a.._.t__-i.., ____ ,..L _ _,._ ___ + fi~_._ __,,...__ _.L_._ •. ~..i---~. 8 () ·-...... __ " ~.· ,..., -() I ~l<_/~ ~ ~ ~ _, ...... !::;, M _..,. :: ~~ ~g~ ___,,. ~m "' ~ ~r;... <> Q ~ --- 0 0 Cl. 0 {I) "' ~ - D p---- 0 0 O ~ D o ~----·---~'° l 8n t. ~ - ---.- :: o I ' '~ ' I o +----.- -, n .,.- ~-T- O o Cj ~ ~ Oo 0 ~ ~ (.)(; • :j (; ; (D) Sc (ppm) (E) h•pm) .., Sc (F) Sc(ppm) I I I I . ' ...... 1._ _.._ ___J_ _ ...... 1.-A.-.. 0 Q. ·-·--"'~-....._____..&.._--....-'----"- 81 0"' 0) ,, ~)_ "' 0"' §~ 8 u ...... 0"" "'0 0 ...... "' ...... 0 0 ...... t ...... ,...... s::_, 0 0 s:: 0 ..... ()"' J 0 0 c. ... .c CD a. ... Q GI c. ,,, :1 0 '.!! Q) (') 0 u· ~ 0 0 u ·Z//' 0 / 8-I ~ () \. "'0 ------() J:_-~ "'0 () u ~ u.-..,u ;;; ~I. I I . I . I . ti 0 I 0 ' <> ---.-.....----- o- ::::; .., w & u ;: 0- a; (0 o-{;) ... ~ 0 0~· 0 0 "' "" "' "' "'"" "'"" "' Figure 12. Influence of local basaltic volcan s based on Sc concentration. A= Columbia County #31-8 B= IW 22d-10 C= Longview Fiber #25-33 01 D= Crown Zellerbach #30-33 E= Crown Zellerbach #2 F= GPE. Federal Com. #1 ~._) TABLE VII GEOCHEMISTRY OREGON NATURAL GAS IW-22d-10 CORE SAMPLE Sample # Depth (ft) Na K Rb Ce Eu Th A-10 1997.5 l.82 .01 1.63 0.15 81. 10.0 118. 7 1.9 3.12 .06 3.51 .19 A-11 2001.5 1.28 .00 2.85 0.16 86. 6. 73.5 l. 3 1.12 .03 9.61 .16 Hf Fe Sc Co LA Sm A-10 1997.5 4.8 .2 7.62 .oa 25.9 .7 17.a .5 41.1 .4 12.07 .05 A-11 2001.5 3.39 .14 3.14 .04 13.7 .4 a.a .3 26.2 .3 5.19 .03 Note: Na, K and Fe in percent oxide Trace elements in ppm m w ------~- --- __..,..,_ ---- 64 TABLE VIII GEOCHEMISTRY RATIO Sc/Co WELL NAME SAMPLE DEPTH (ft) Sc/Co (ppm} America Quazar Petroleum corp. CC-Al 700 3.63 Colwnbia county 31-s CC-A2 720 l..60 CC-Al 910 l..68 CC-A4 1000 2.10 CC-AS 12 l.O l.98 CC-A6 1420 2.51 CC-A7 l.Sl.O l.58 CC-AS 1600 2.01 CC-A9 2020 1.84 CC-AlO 2200 2.os CC-All 2440 l.37 cc-Al.2 2470 1.21 CC-A13 2500 l..58 CC-Al4 2560 l.07 CC-Al.S 2680 l.06 CC-Al6 2740 0.90 CC-Al.7 2830 1.06 CC-Al8 2920 l.l.3 CC-Al9 3010 l.02 CC-A20 3100 l.14 CC-A2l 3820 i.o5 CC-A22 3850 0.81 CC-A23 3880 0.67 Oreqon Natural Gas IW l 720 2 .16 IW 22d-l0 IW l3 1590 l.90 IW l4 1680 l.87 IW 15 1800 l. .88 IW 2 1920 l. 69 IW 3 1950 1. 71 IW 4 1980 l..79 IW 5 2040 l..54 IW 6 2070 l. 42 IW 7 2100 l.44 IW 8 2200 l.02 IW 9 2310 0.68 IW 12 2520 0.76 IW 10 2700 0.95 IW l.l 2770 0.36 America Quazar Petroleum corp. LF l 500 l..64 Longview Fiber # 25-33 LF 2 590 l..39 LF 3 680 l.29 LF 4 800 l.44 LF s 890 l.43 LF 6 980 l..36 LF 7 1070 l.34 65 TABLE VIII GEOCHEMISTRY Sc/Co RATIO (continued) WELL NAME SAMPLE DEPTH (ft) Sc/Co (ppm) America Quazar Petroleum Corp. CZ l 1350 1.38 crown Zellerbach #30-33 CZ 2 1440 1.77 CZ 3 1530 l. 72 CZ 4 1620 1.33 CZ 5 1770 1.08 Reicchhold Enerqy corp. CZ2 l 2770 l. 47 crown Zellerbach # 2 CZ2 2 2920 1.49 CZ2 3 2980 1.55 CZ2 4 3100 1.17 CZ2 5 3220 0.70 Exxon company-USA GPE 15 1000 1.86 G.P.E General comp. #1 GPE 16 1500 l. 74 GPE 31 2200 1.88 GPE 17 2500 1.47 GPE 18 3000 1.54 GPE 19 3200 1.06 GPE 20 3260/70 0.95 GPE 21 3430/50 l. 38 GPE 22 3500 1.18 GPE 8 4100 1.00 GPE 9 4200 1.10 GPE 10 4300 1.12 GPE 11 4400 l. 32 GPE 12 4500 1.50 GPE 13 4600 l.SO GFE 14 4700 1.05 GPE l 7500 l.11 GPE 2 7600 1.10 GPE 3 7700 1.10 GPE 4 7800 1.14 GPE 5 7900 0.90 GPE 6 8000 0.71 GPE 7 8100 0.90 GPE 23 9700/20 0.99 GPE 24 9800 l.07 GPE 25 9900 l. 32 GPE 26 9950/20 1.01 SUBSURFACE ANALYSIS SUBSURFACE CORRELATION Interpretation of the subsurface stratigraphy of northwestern Oregon has been done based on the analysis of mud logs, electric logs, spontaneous potential, and the gamma ray log responses of fifteen wells located in the Astoria basin, Mist gas field and northern Willamette Valley. These logs are useful because they: a) differentiate potentially porous and permeable reservoir rocks (sandstone) from nonpermeable (clay), b) aid in lithological identification and c) define bed boundaries and permit correlation of beds. Niem and others (1985) described the log responses for each formation in the Astoria basin, and the same criteria is used herein in order to interpret the other wells (refer to plate I wells Patton #32-9, Clatsop County #33-11, and Cooper Mountain #1) • Tillamook Volcanics show a large increase in the resistivity curve, a negative deflection of SP curve from the shale line, and low intensity of the gamma ray. The Hamlet formation resistivity is moderate to high, depending on which member of the formation the well penetrated. In the sand the resistivity is high. The SP ------··----··-- 67 log is variable; it can be close to the shale line in the mudstone and increases in the sand. The gamma ray curve is smaller in the Hamlet formation than in the underlying Tillamook Volcanics. The Cowlitz Formation shows two different responses. The Clark and Wilson sand in the Mist gas field has low to moderate resistivity, high SP, and high gamma ray. The mudstone shows a decrease in the resistivity and SP curve and a slight decrease in the gamma ray. The Clark and Wilson sand in Clatsop County shows an increase in resistivity over that of the underlying Hamlet formation. The SP and gamma ray values are variable. The Keasey Formation resistivity and SP curves are low and nearly a straight line. The gamma ray curve shows a large decrease compared to the underlying Cowlitz Formation. The Smuggler Cove formation resistivity, gamma ray and SP curves are variable to nearly straight-line. The Sager Creek formation resistivity, gamma ray and SP curve are nearly straight lines. Gamma ray increases from the Keasey Formation. The Astoria Formation in the Clatsop County shows an increment on both resistivity and SP curves over that of the Smuggler Cove Formation. The Pittsburg Bluff Formation resistivity curve is nearly a straight line and the SP curve is variable. The gamma ray curve increases over that of the Keasey Formation. 68 For the Spencer Formation in the Willamette Valley the resistivity and the SP curves are more variable than that of the underlying Keasey Formation and the overlying Eugene Formation and show a large increase in the sandstone interval. The resistivity and SP curves of the Columbia River basalt are high, which is typical of volcanics. The Subsurface stratigraphy of the study area is shown in Plate I and Plate II. The following comments describe the interpretation of the stratigraphy in individual wells: Patton #33-9 well. The Patton #33-9 well penetrates the Astoria, Smuggler Cove, Keasey and Hamlet formations. Here, the Cowlitz Formation is not present. The Smuggler Cove Formation is approximately 4,650 ft thick in this well. Clatsop County #33-11 well. The Clatsop County # 33-11 well penetrates the sager Creek, Keasey, Cowlitz formations and Tillamook Volcanics. The Cowlitz Formation is thin and pinches out toward the east (Patton 33-9 well). The thickness of the Keasey Formation is approximately 1,800 ft. The contact between the Cowlitz and Keasey is at 3,830 ft (SSL=-2,890 ft). Columbia County #31-8 well. The Pittsburg Bluff, Keasey, Cowlitz, and Hamlet are formations encountered in this well. From 2,450 ft to 3,400 ft the gamma ray increases and 69 decreases intermittently. The gamma ray curve could be interpreted as an interf ingering of the Keasey and Cowlitz formations (Jack Meyer personal communication, 1989) or as reworked sediments from the Keasey and Cowlitz formations deposited as an alluvial fan after partial erosion of the Cowlitz Formation during the deposition of the Keasey Formation, or sediments deposited from other sources. The contact between the Cowlitz and Keasey cannot be determined here. Columbia County IW 22d-10 well. This well is a shallow well that only penetrates Pittsburg Bluff, Keasey and Cowlitz formations. The contact between the Cowlitz and the Keasey formations is at 1,995 feet (SSL= -1,197 ft). Columbia County #32-10 well. The Columbia County #32-10 well penetrates the Keasey, Cowlitz, Hamlet formations and a thick section of the Tillamook Volcanics. The contact between the Cowlitz and Keasey formations is at 1,850 feet (SSL=-1,030.2 ft). Volcanics are encountered at 2,800 ft (SSL=-1,980.1 ft) under the Clark and Wilson sand with a thickness of 600 feet. The Sunset Highway member of the Hamlet formation is located at 3,440 ft (SSL=-4,226.8 ft) with a thickness of 120 feet, and pinches out to the east. Columbia County #1 RD 1 well. Only two formations are penetrated by this well. Keasey and Cowlitz show their 70 contact at 1,940 ft {SSL=-908.5 ft) Longview Fiber #25-33 well. The Longview Fiber is a deep well which penetrates the Keasey, Cowlitz, and Hamlet formations and Tillamook Volcanics. In this well, the Hamlet formation is interbedded with the Tillamook Volcanics. The sunset Highway member of the Hamlet formation (Clatskanie sand of the Yamhill Formation) is present at 3,230 feet {SSL=-2,440.5 ft). The contact between Cowlitz and Keasey is at 820 ft {SSL=-30.5 ft). Crown Zellerbach #33-30 well. The Keasey and Cowlitz formations are the only ones penetrated by this well. The contact between these two formation is at 1,075 ft (SSL=- 233.0 ft). Crown Zellerbach #34-26 well. The Crown Zellerbach #34-26 penetrates the Keasey, Cowlitz, and Hamlet formations. The thickness of the Cowlitz mudstone increases in this section. The Cowlitz and Keasey contact is at 3,790 ft (SSL= 2,892 ft). The Sunset Highway sandstone is present at 5,550 ft {SSL= -4,657.0 ft). Crown Zellerbach #2 well. This well only penetrates the Keasey Formation, a lava flow, and the Cowlitz Formation. The lava flow encountered at 2,840 ft (SSL=-2,151.0 ft), separates the Cowlitz from the Keasey. Therefore, the 71 contact between these two formation cannot be defined. GPE Federal Com. #1 well. The GPE Federal Com. #1 well penetrates the Keasey Formation, a section rich in volcanics, silty and clayey sediments, and the Cowlitz Formation. The volcanic section is encountered at 4,100 ft (SSL=-2,344 ft). It could be interpreted as local volcanic activity prior to the deposition of the Keasey Formation. However, the gamma ray curve at the 8,500-8950 ft interval shows an downward decrease typical of the Keasey Formation. This change of the curve could be interpreted, as the deposition of the Keasey Formation before the volcanic activity started. Once this volcanic activity ended, the Keasey continued being deposited. Sand encountered at 10,500 ft (SSL=-8,744.0 ft) is equivalent to the Clark and Wilson sand of the Cowlitz Formation (Meyer personal communication, 1990). Cooper Mountain #1 well. The Cooper Mountain well penetrates the Columbia River basalt, Pittsburg Bluff, Keasey, Spencer and Yamhill formations and the Tillamook Volcanics. Werner #14-21 well. The Columbia River basalt, Eugene and the Spencer formations are penetrated by the Werner #14-21 well. 72 Wilna ET AL #5-23 well. The Wilna ET AL # 5-23 penetrates the Keasey and Cowlitz formations, volcanics, the Hamlet formation, and the Tillamook Volcanics. The Clark and Wilson sand of Cowlitz Formation is encountered at.1,900 ft (SSL=-400 ft). The gamma ray curve, in the 1,200-1,900 ft interval increases and decreases intermittently as it was observed in the Columbia County #31-8 well. These two wells are located in the opposite side of the Nehalem arch. This particular response of the gamma ray curve has been observed in others wells located off the arch (the Arco Exploration Company, Columbia county #23-19 and American Quasar Petroleum Corp., Crown Zellerbach #15-14 wells). The gamma ray curve response can be interpreted as the interf ingering of the Keasey and Cowlitz formations. CROSS SECTION INTERPRETATION Subsurface stratigraphy of northwestern Oregon. Cross section 1 (Plate I). From the cross section (Plate I), it can be observed that the Hamlet formation is present in the Astoria basin where it has great thickness toward the basin and then thins out toward the Nehalem arch of Armentrout and Suek (1985), where it pinches out in Clatsop County #33-11 well; here, the Cowlitz Formation unconformably overlies the Tillamook Volcanics. In Columbia County the Hamlet formation (Yamhill Formation of Bruer and others, 1984) increases its thickness 73 toward the Willamette Valley, where it interfingers with the Tillamook Volcanics. The Sunset Highway member of the Hamlet formation can be correlated through the Columbia County #32-10, Longview Fiber #25-33, and Crown Zellerbach #34-26 wells. The Clark and Wilson sandstone of the Cowlitz Formation shows a great decrease in thickness from the Astoria basin toward the Nehalem arch. In Columbia County, on the other side of the arch the sand thickness again increases. The mudstone in the highest part of the arch is thin but thickens toward the east to approximate 3000 feet. In the Columbia County #32-10 well, a basalt flow underlies the Clark and Wilson sand of the Cowlitz Formation. A thick section of reworked sediments or interf ingering sediments of the Cowlitz and Keasey formations overlies the mudstone of the Cowlitz Formation in the Columbia County #31-8 well. In the GPE Federal Com. #1 well the Cowlitz Formation is present at 9,200 feet, where it is overlain by a thick volcanic deposit interbedded with marine clays and siltstones. The Keasey Formation unconformably overlies the Hamlet formation in Clatsop County (Astoria basin) and the Cowlitz Formation in Clatsop and Columbia counties. However, in the Columbia County on the flank of the Nehalem arch, the Keasey Formation is conformable with the Cowlitz Formation. The Keasey Formation interfingers with the Eugene Formation in the Willamette Valley where it decreases in thickness. In 74 the Astoria basin, the Keasey Formation is conformably overlain by the Smuggler Cove formation in the Patton #32-9 well and is unconformably overlain by the Sager Creek formation in Clatsop county #33-11 (Niem and others, 1985). The Sager Creek formation pinches out to the southwest. The Pittsburg Bluff Formation overlies the Keasey Formation in Columbia County. In Washington County the Keasey Formation is underlain by the Spencer Formation and overlain by the Pittsburg Bluff Formation. The Keasey Formation is probably equivalent to the lower part of the Eugene Formation in Marion County. The Columbia River Basalt Group overlies the Pittsburg Bluff in the Cooper Mountain #1 well. Toward the south in Marion County, the Spencer Formation thins. It is overlain by the Eugene Formation. Subsurface stratigraphy of northwestern Oregon. Cross section 2 (Plate II) . In this cross section only five wells were correlated (Columbia County #31-8, IW 220-10, Columbia County #32-10, Columbia County #1 RD #1 and Wilna ET AL No 5-23). The correlation among the wells is the same as in plate I, except the Wilna ET AL No 5-23 well has been added. The Wilna ET AL No 5-23 well is located off the axis of the arch, on the opposite side from the Columbia County #31-8 well. The interfingering of the Keasey and Cowlitz formations is observed on both flanks of the arch. The 75 contact relationship between the Keasey and the Cowlitz is unconformable along the axis of the arch, but on the flanks the two formations interfinger the contact is conformable. DISCUSSION AND CONCLUSION The concentrations of K, Th, Rb and Sc/Co ratio in the Cowlitz and Keasey formations aid in the identification of the contact between these two formations in wells sampled. This geochemical contact was well-defined in the Columbia County IW 220-10 well at 1,995 ft and Longview Fiber #25-33 well at 600 ft, and coincides with the gamma ray log break, but not with the Refugian/Narizian paleontological time boundary. The break between the Narizian and Refugian in the Longview Fiber #25-33 well is at 590 ft, but in the Columbia County IW 220-10 well it could not be determined because the paleontological information available was limited. In the Columbia County #31-8 well, the variable concentration of K, Th ,Rb and Sc coincide with the irregular response of the gamma ray curve in the 2,450-3,400 ft interval. The result could be due to the interfingering of the Cowlitz and Keasey formations, or to the deposition of reworked sediments. These sediments could be deposited as a slump caused by landslide or as an alluvial fan caused by normal faulting during the time of deposition of the Keasey Formation. Up section from this interval, the Keasey Formation can be distinguished by either method. The Refugian/Narizian paleontological time boundary is higher into the Keasey 77 Formation, and this is also observed in most of the others wells. The fact that the Refugian/Narizian paleontological time boundary is in the Keasey, indicates that the assumption that the Keasey formation is only Refugian is wrong. It is clear that it was deposited during the late Narizian and Refugian time, and that the fauna composition was not affected by the lithology, but by regional or worldwide factors such as water depth, water temperature, paleogeography, and volcanism. In the Crown Zellerbach #32-10 well the electric and the SP logs and lithological break coincides with the paleontological break, and this could be due to the erosion or non deposition of the Cowlitz Formation prior to the deposition of the Keasey Formation. The break between the Keasey Formation and volcanic sediments could be distinguished chemically by the their higher Sc and lower Rb and by the highly variable responses of the electric log in the volcanic sediments. The Crown Zellerbach #2 well and the GPE Federal Com.#1 well show these breaks at 2,840 ft and 3,150 ft respectively. Since in these two wells the Keasey is overlain by volcanics, there is no direct contact between the Keasey and the Cowlitz formations. The Refugian/Narizian contact has not been determined in these wells. The gamma ray response provides geophysical evidence 78 for the interfingering relationship between the Cowlitz and the Keasey formation. This interfingering could be due to the intermittent deposition of these formations during the growth of the cascades and the uplift of the arch. The Cowlitz Formation stoppep depositing once the Cascades formed and plugged and/or deluted the sources of the Cowlitz sediments. Erosion of the Cowlitz Formation from the upper part of the arch could be due to the uplift of the arch. CONCLUSION Geochemical concentration of K, Th, Rb and Sc/Co helped to identify the contact between the Keasey and Cowlitz formations and the basaltic volcanic sediments. The Keasey Formation is characterized by having low K, low Rb, low Th and high Sc/Co ratio. The Cowlitz Formation has high potassium, high Rb, high Th and low Sc/Co ratio. Sediments with basaltic volcanic influence can be differentiated by their high Sc and low Rb concentrations. The Narizian and Refugian paleontological boundary differs from the geochemical, lithological and geophysical (electric, SP and gamma logs) contact between the Keasey and the Cowlitz formations in most parts of northwestern Oregon. The Stage-Stage contact is located within the Keasey Formation. However, in some places it coincide with the lithological contact defining an unconformity or non deposition. The gamma ray log defines an interfingering 79 relationship between the Cowlitz and the Keasey formations, therefore they are conformable in some localities. Geophysical (gamma ray, electric, and SP logs) and geochemical techniques can be used as an aid in defining the contact between two formations when the lithology cannot be distinguished. PROBLEMS AND SUGGESTIONS The Columbia County #31-8 well represents a puzzle in the fact that the 2,450-3,400 ft interval shows irregular geophysical responses and that the geochemistry is not consistant. In order to prove geochemically that the Keasey Formation and the Cowlitz Formations are interfingering, I suggest testing these wells with samples collected at closer intervals than those chosen here, in order to include each bed. REFERENCES Alger, M.P., 1985, Mist gas field: exploration and development 1979-1984: Oregon Dept. Geol. and Min. Ind., Oil and Gas Inv. 10, p. 6-9. Armentrout, J.M., D.A. Hull, J.D. Beaulieu, and W.W. 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Drake, E.T., 1982, Tectonic evolution of the Oregon continental margin: Oregon Geology Vol. 44, No.2, p.15-24. Farr Jr, L.C, 1989, Stratigraphy, diagenesis, and depositional environment of the Cowlitz Formation (Eocene), Northwest Oregon: unpub. M.S. thesis Portland State Univ., Portland, Oregon, 168 p. Heller, P.l., and Ryberg, P.T., 1983, Sedimentary record of subduction to forearc transition in the rotated Eocene basin of western Oregon: Geology, V.11, p. 380-383. Jackson, M.K., 1983, Stratigraphic relationships of the Tillamook Volcanics and the Cowlitz Formation in the upper Nehalem River Basin, Northwest Oregon: Uunpub. M.S. thesis, Portland State University, Portland, Oregon, 110 p. Kadri, M.M., 1982, Structure and influence of the Tillamook uplift on the stratigraphy of the Mist area, Oregon: unpub. M.S. thesis, Portland State University, Portland Oregon, 105 p. Kadri, M.M., M.H. Beeson and R.O. Van Atta, 1983, Geochemical evidence for changing provenance of Tertiary formations in northwestern Oregon: Oregon Geology, v. 45, p.20-22. Kelty, K., 1981, Stratigraphic, lithofacies and environment of deposition in central Columbia County, Oregon: unpub. M.S. thesis, Portland State University, Portland, Portland, Oregon, 81 p. Kleinpell, R.M., 1938, Miocene stratigraphy of California: Tulsa, Oklahoma, American Association of Petroleum Geologist, 450 p. ----·····--···- 82 Lawrence, R. D. 1976, Strike-Slip faulting terminates the basin and range province in Oregon: Geol. soc. Amer. Bull., Vol. 87, p. 846-850. Magill, J.R; Cox, A.V, and Duncan, R. A, 1981, Tillamook Volcanic Series: further evidence for tectonic rotation of the Oregon Coast Range: Jour. Geophys. Res., v. 86, p. 2953-2970. Mallory, v.s., 1959, Lower Tertiary biostratigraphy of California coast ranges: Tulsa, Oklahoma, American Association of Petroleum Geologists, 416 p. Mayer, H.J,, Geologist, Oregon Natural Gas Development Corp. McKee B., 1972, Cascadia: The geologic evolution of the Pacific Northwest: New York, McGraw-Hill Book Co. 394 p. McKeel, D, 1983, Subsurface biostratigraphy of the east Nehalem basin, Columbia County, Oregon: state of Oregon Department of Geology and Mineral Industries, Oil and Gas Investigation 9. McKeel, D.R, 1984, Biostratigraphy of exploratory wells, Northern Willamette basin, Oregon: State of Oregon Department of Geology and Mineral Industries, Oil and Gas Investigation 12, 19p. Nelson, D.E., 1985, Geology of the Jewell-Fishhawk Falls area, Clatsop County, northwestern Oregon: unpub. M.S. thesis, Oregon State Univ., Corvallis, 204 p. Nelson, M.P,., 1978, Tertiary stratigraphy and sedimentation in the Lewis and Clark River-Youngs River Area, Clatsop County, nothwestern Oregon: unpub. M.S. thesis, Oregon State Univ., Corvallis, 148 p. Newton v.c., 1969, Subsurface Geology of the lower Columbia and Willamette basin, Oregon: State of Oregon Department of Geology and Mineral Industries Oil and Gas investigation 2, 121p. Newton, v.c. Jr, and Van Atta, R.O., 1976., Prospects for natural gas production and underground storage of pipe- 1 ine gas in the upper Nehalem River basin, Columbia Clatsop counties, Oregon: Oregon Dept. of Geol and Min. Indus. Oil and Gas Invst 5, 56 p. 83 Niem A.R and Niem W.A. 1985, Oil and gas investigation of the Astoria basin, Clatsop and northernmost Tillamook Counties, northwest Oregon: Oregon Department of Geology and Mineral Industries Oil and Gas Investigation 14 ap.,2 plates. Niem, A.R., Niem W.A., Martin, M.W., Kadri, M.M. and Mc Keel, D.R., 1985, Correlation of exploration wells Astoria basin, Northwestern Oregon: Oregon Department of Geology and Mineral Industries oil and gas investigation 14, Sp. Niem, A.R., and Van Atta, R.O., 1973, Cenozoic stratigraphy of northwestern Oregon and adjacent southwestern Washington: Oregon Dept. of Geol. and Mineral indust. Bull. 77, p. 75-89. Olbinski, J.S., 1983, Geology of the Buster Creek-Nehalem Valley area, Clatsop County, northwest Oregon: Unpub. M.S. thesis, Oregon State univ., Corvallis, 231 p. Olmstead, o.L, 1985; Mist Gas Field: exploration and development 1979-1984: State of Oregon Department of Geology and Mineral Industries, Oil and Gas Investigation 10. Rarey, P.J, 1985, Geology of the Hamlet- north fork of the Nehalem River area, Southern Clatsop and Northern Tillamook counties, Oregon: Unpub, M.S thesis, Oregon State University, Corvallis. 457 p. Rock-color Chart Committee, 1970, Rock color chart Boulder co. Geol. Soc. Am. Safley, L.E, 1989, Geology of the Green Mountain- Military Greek area, Clatsop and Tillamook counties, Northwestern Oregon (M.S. thesis): Unpub. M.S. thesis, Oregon State University, Corvallis, 240 p. Schenck, H.G., and Kleinpell, R.M., 1936, Refugian stage of Pacific coast Tertiary: American Association of Petroleum Geologist Bulletin, v.20, no.2, p. 215-225. Shaw, N.B., 1986 Biostratigraphy of the Cowlitz Formation in the upper Nehalem River basin Northwestern Oregon: unpub. M.S. thesis, Portland State University, Portland, Oregon. lOlp. Simpson, R.W., Cox, A., 1977, Paleomagnetic evidence of tectonic rotation of the Oregon Coast Range: Geology, vol.5, p. 585-589. 84 Snavely, P.O. Jr, Warner, H.C., and Lander, D.L. 1980, Interpretation of the Cenozoic geologic history, central Oregon Continental margin: Cross section summary: Geol, Soc. Amer. Bull, vol 91, part I, p. 143- 146 Suek, D.H., 1982, Pacific Northwest Exploration Report: Denver Colorado, Snyder Oil Co. unpublished company report, 54 p. Thoms, R.E., Van Atta, R.O, and Taylor, D.G., 1983, Stratigraphy and paleontology of selected sections in the Paleogene rock of the western Tualatin Valley borderlands, northwest Oregon: Unpublished report, 83 p. Timmons, D.M, 1981, Stratigraphy, lithofacies and depositional environment of the Cowlitz Formation T4 and 5N, R5W, Northwest Oregon: Unpub. MS thesis, Portland State University, Oregon, 89p. Tolan, T.L. and Beeson, M.H., 1984, Exploring the Neocene history of the Columbia River: Discussion and geologic field trip guide to the Columbia River George: Oregon Geology, vol. 46, No. 8, p. 87-97 Tolan, T.L., Reidel, S.P., Beeson, M.H., Anderson, J.L., Fecht, K. R., and Swanson, D.A., 1989, Revision to the estimates of the areal extent and volume of the Columbia River Basalt Group, in Reidel, S.P., and Hooper, P.R., eds., Volcanism and tectonism in the Columbia River flood-basalt province: Boulder Colorado, Geological Society of America, Special Paper 239. van Atta, R.O., 1971, Sedimentary petrology of some Tertiary formations upper Nehalem River basin, Oregon: PH.D dissertation (unpub). Oregon State University., Corvallis, Oregon, 245p. Van Atta, R.O. and Kelty B. K., 1985, Scappoose Formation Columbia County, Oregon: New evidence of age and relation to Columbia River Basalt Group: Amer. Assoc. Pet. Geol. Bull., vol.69, no.5, p. 688-698. Warren, w.c., Grivetti, R.M., and Norbisrath, H., 1945, Geology of Northwestern Oregon, west of the Willamette River and north of latitude 45°15': U.S. Geological Survey Preliminary Oil and Gas Investigation Map 42, scale 1 in.:2.25 mi. ~~~----~ 85 Warren, w.c., and Norbisrath, H., 1946, Stratigraphy of upper Nehalem River basin, northwestern Oregon: Amer. Assoc. Pet. Geol. Bull., vol. 30, no.2, p.213-237. Wells F.G and Peck, D.L, 1961, Geologic map of Oregon west of the 121st meridian: U.S.G.S. Invest. Map GQ, J-325. Wells, R.E., Niem, A.R., MacLeon, N.S., Snavely, P.O., Jr., and Niem, W.A., 1983, Preliminary geologic map of the west half of the Vancouver (Wa.-Ore.) 1° X 2° quadrangle, Oregon: U.S. Geological Survey Open-File Report 83-591, scale 1:250,000. APPENDIX SAMPLES DESCRIPTIONS Chips and core samples were examined and described using a binocular microscope. Colors definition are derived from Rock color chart Boulder Co. Geel. Soc. Am. American Quasar Petroleum Corp. Longview Fiber #2S-33 Sample Depth Description LF 1 S00-530 Light olive gray Sy 6/1 siltstone, with mica and tuff. LF 2 S90-620 Light olive gray Sy 6/1 siltstone, mica, slightly calcareous. LF 3 680-710 Light olive gray 5y 6/1 siltstone, slightly calcareous. LF 4 800-830 Light olive gray Sy 6/1 mudstone. LF 5 890-920 Light olive gray 5y 6/1 silty mudstone, slightly calcareous LF 6 980-1010 Greenish gray 5 Gy 6/1 mudstone. LF 7 1070-1100 Greenish gray S Gy 6/1 slightly silty mudstone. 87 American Quasar Petroleum Corp. Crown Zellerbach #30-33 Sample Depth (ft) Description CZ 1 13SO Greenish gray S Gy 6/7 mudstone, volcanic fragments, micaceous. CZ 2 1440 Light olive gray Sy 6/1 mudstone, volcanic fragments. CZ 3 1S30 Light olive gray Sy 6/1 mudstone, volcanic fragments. CZ 4 1620 Light olive gray Sy 5/2 slightly silty mudstone, quartz, slightly calcareous. CZ 5 1770 Light olive gray Sy 5/2 Silty and, micaceous, volcanic fragments, calcareous. 88 Reichhold Energy Corp. Crown Zellerbach #2 Sample Depth (ft) Description CZ2-l 2770-2800 Dark yellowish brown 10 yr 4/2 sandstone, abundant volcanic fragments. CZ2-2 2900-29SO Light olive gray Sy 6/1 tuffaceous mudstone, basaltic fragments. CZ2-3 2980-3010 Light olive gray Sy 6/1 tuffaceous mudstone, basalt, quartz. CZ2-4 3100-3110 Pale yellowish brown 10 yr 6/2 sandy silty mudstone, volcanic fragments. CZ2-S 3220-3230 Light olive gray Sy S/2 siltstone, volcanic fragments, quartz. 89 Oregon Natural Gas Columbia County IW-220-10 Sample Depth (ft) Description IW 1 720 Light olive gray Sy 6/1 siltstone IW 13 1S90 Light olive gray Sy 6/1 siltstone. IW 14 1680 Light olive gray Sy 6/1 siltstone. IW lS 1800 Light olive gray Sy 6/1 mudstone with chert grains. IW 2 1920 Light olive gray Sy 6/1 siltstone, silica grains. IW 3 1950 Light olive gray Sy 6/1 silty mudstone, basalt. IW 4 1980 Light olive gray Sy 6/1 mudstone, volcanic fragments, chert grains. IW S 2040 Light olive Sy 6/1 mudstone, tuffaceous, mica, pyrite. IW 6 2070 Light olive gray Sy 6/1 Mudstone, micaceous. IW 7 2100 Light olive gray Sy 6/1 mudstone, micaceous. IW 8 2200 Light olive gray Sy 6/1 sandstone, medium-fine grained, volcanic fragments. IW 9 2310 Moderate brown S yr 4/4 sandstone, medium-fine grained, micaceous, volcanic fragments. IW 10 2520 Pale olive lOy S/4 sandstone, micaceous, calcite. 90 IW 12 2700 Greenish gray Sy 6/1 sandstone, volcanic fragments, micaceous. IW 11 2770 Light olive gray Sy 6/1 tuffaceous mudstone, volcanic fragments 91 Arco Oil and Gas Company Columbia County # 31-8 Sample Depth (ft) Description CC-Al 700 Yellowish gray Sy 7/2 mudstone, micaceous. CC-A2 820 Light olive gray Sy 6/1 mudstone, micaceous. tuff. CC-A3 910 Light olive gray Sy 6/1 mudstone, micaceous, tuff. CC-A4 1000 Pale olive lOy 6/2 tuffaceous siltstone. CC-AS 1210 Pale olive 10 y 6/2 tuffaceous, siltstone. CC-A6 1420 Light olive gray Sy 6/1 tuffaceous siltstone. CC-A7 lSlO Pale yellowish brown 10 yr 6/2, sandstone, coarse grained, volcanic fragments. CC-AS 1600 Light olive gray Sy 6/1 siltstone, micaceous, tuffaceous. CC-A9 2020 Greenish gray S Gy 6/1 siltstone, micaceous, volcanic fragments, tuff. CC-AlO 2200 Greenish gray S Gy 6/1 siltstone, micaceous, tuff. CC-All 2440 Light olive gray Sy 5/2 siltstone, volcanic fragments, tuff, calcite, pyrite, mica. CC-A12 2470 Light olive gray 5y 5/2 siltstone, volcanic fragments, micaceous, pyrite. 92 CC-Al3 2SOO Light olive gray Sy S/2 siltstone, volcanic fragments, mica, calcite, pyrite. CC-A14 2S60 Greenish gray S Gy 6/1 siltstone, volcanic fragments, pyrite. CC-All 2500 Greenish gray 5 Gy 6/1 silty sandstone, volcanic fragments, pyrite, calcite. CC-A14 2S60 Greenish gray 5 GY 6/1 siltstone, volcanic fragments, pyrite. CC-AlS 2680 Greenish gray s Gy 6/1 silty sandstone, volcanic fragments, calcite, pyrite. CC-Al6 2740 Greenish gray 5 Gy 6/1 siltstone, tuffaceous, volcanic fragments, calcite, pyrite, quartz. CC-A17 2830 Greenish gray s Gy 6/1 sandy siltstone, quartz, mica, volcanic fragments. CC-Al8 2920 Light olive gray Sy 6/1 mudstone, calcite, volcanic fragments. CC-Al9 3010 Greenish gray s 6Y 6/1 siltstone with volcanic fragments. CC-A20 3100 Greenish gray s Gy 6/1 siltstone, volcanic fragments, calcite, pyrite. CC-A21 3820 Light olive gray Sy 6/1 siltstone with volcanic fragments. CC-A22 3850 Light olive gray Sy 6/1 siltstone with volcanic fragments. 93 CC-A23 3880 Dark greenish gray 5 Gy 4/1, volcanic sandstone. ------ 94 Exxon Company - USA G.P.E. Federal Com. #1 sample Depth (ft) Description GPE 15 1000 Light olive gray 5y 5/2 mudstone, micaceous, pyrite, volcanic fragments, quartz, tuff. GPE 16 1500 Light olive gray 5y 5/2 siltstone, micaceous. GPE 31 2200 Light olive gray 5y 5/2 siltstone, volcanic fragments. GPE 17 2500 Light olive gray 5y 5/2 siltstone, volcanic fragments. GPE 18 3000 Grayish olive lOY 4/2 siltstone, volcanic fragments. GPE 19 3200 Light olive gray 5y 5/2 mudstone, volcanic fragments, quartz. GPE 20 3260/70 Basalt. GPE 21 3430/50 Basalt. GPE 22 3500 Light olive gray 5y 5/2 mudstone, volcanic fragments, mica, obsidian. GPE 8 4100 Grayish olive lOy 4/2 silty sandstone, volcanic fragments, tuffaceous. GPE 9 4200 Olive gray 5y 4/1 Silty sandstone, volcanic fragments, trace of pyrite, tuffaceous. GPE 10 4300 Light olive gray 5y 5/2 siltstone, volcanic fragments, trace of pyrite. 9S GPE 11 4400 Grayish olive 10 y 4/2 siltstone, volcanic fragments, trace of pyrite. GPE 12 4SOO Dark yellowish brown 10 yr 4/2, volcanic sand, calcite, basalt. rhyolite. GPE 13 4600 Olive gray Sy 4/1 volcanic sand, basalt, rhyolite, trace of pyrite. GPE 14 4700 Light olive gray Sy S/2 Siltstone, basalt. GPE l 7500 Light olive gray 5y S/2 mudstone, volcanic fragments, calcite. GPE 2 7600 Light olive gray Sy S/2 siltstone, micaceous, volcanic fragments. GPE 3 7700 Light olive gry 5y S/2 siltstone, calcite, quartz, volcanic fragments. GPE 4 7800 Light olive gray Sy S/2 siltstone, tuffaceous, volcanic fragments. GPE S 7900 Olive gray Sy 4/1 siltstone, volcanic fragments. GPE 6 8000 Olive gray Sy 4/1 siltstone, volcanic fragments. GPE 7 8100 Olive gray 5y 4/1 Volcanic sandstone. GPE 23 9700-20 Basalt GPE 24 9800 Light olive gray Sy S/2 mudstone, tuffaceous, volcanic fragments. GPE 2S 9900 Olive gray Sy 4/1 mudstone, tuffaceous, 96 volcanic fragments. GPE 26 10,000 Olive gray Sy 4/1 mudstone, tuffaceous, volcanic fragments, quartz. GPE 27 10,SOO Olive gray Sy 4/1 Siltstone, volcanic fragments, tuffaceous. GPE 28 11,000 Olive gray Sy 4/1 silty, volcanic fragments, pyrite. GPE 29 11,280 Light olive gray Sy 6/1 tuffaceous mudstone. 97 Core Sample Description Columbia County IW 22D-10 Sample Depth (ft) Description A-10 1997.5 Dusky yellow green 5 Gy 5/2, conglomeritic sand, with basalt, rhyolite, fossil fragments, mica, calcite. A-11 2001.5 Dark greenish gray 5 Gy 4/1, mudstone, micaceuos, fossiliferous (Bulimina microcostata).