OREGON GEOLOGY formerly THE ORE BIN published by the Oregon Department of Geology and Mineral Industries Volume 41 , Number S August 1979 • '" ~~ : . ~ .- _ "l.., J' , • s, . .. o :I - ' . .. 1"" ~. t:. ' ... -:-... ......... ' ... .. .. ...... _- <'It-• • . " - .. "o _"~ I: - .' ""- .. -.. .....• • .. • -: ,, • .,, • . :.. Friends of Mineralogy to hold fifth annual OREGOM GEOLOGY symposium in September (ISSN 0164-3304) The Friends of Mineralogy, Northwest Chapter, will August 1979 Volume 41, NumberS hold their fifth annual symposium, "Sulfides and Sulfo­ salts," September 28 th rough 30, 1979, at the Bellevue Published monthly by the Slale of Oregon Department of Holiday Inn on Interstate 405 just across Ihe noating Geology and Mineral Industries (Volumes ] through 40 ",ere en- titled The Ore Bin). bridge from Seattle, Washi ngton. Symposium hours will be 7 p.m. to 11 p.m. Friday, 8 a.m. to 11 p.m. Saturday, and 8 a.m. to 12 a.m. Sunday. Gnernlng Board Speakers will be Joseph Mandarino, Curator, Leeanne G. MacColl, Chairperson . .... .. .. .. Portland Robert W. Doly . ... .. .. .. Talent Royal Ontario Museum; Les Zeihen. Consulting Miner­ John L Schwabe . .. .. .. .. .. .. .. ... .. Portland alogist for the Anaconda Company, Bulte, Montana; Stale Geologist .. .. ... .. .. .. .. .. .. Donald A. Hull Robert Cook. Associate Professor of Ge.olpgy, Auburn UniversilY. Auburn, Alabama; Joe Nagel and Colin Deputy Stalt Geolagist . .. ..... ... ... John D. Beaulieu Goodwin , University of British Columbia, Vancouver, B.C.. Canada; and Bob Jackson, Collector, Renton, Ed ltDr . ... .. .. ... .. .. .. ... .. Beverly F. Vogi Washington. Lectures will be centered about the theme, Mlin Offic.: 1069 Sialt Office Building, Ponland 97201, phone "Sulfides and Sulfosaits." (303) 229-5580. Approximately iO to 20 noncompetilive, educa­ Baker field Olliel: 2033 First Street, Baker 978 14, phone (503) tional exhibits related to finely crystallized sulfides and 523-3133. sulfosalts are anticipated. Howard C. Brooks, Resident Geologist Three well-known dealers, Nature's Treasures. The Grants Pass fie ld Ollie,: 312 S. E. "H" Street, Granls Pass 97526. Mineral. Mailbox, and Lidstroms. wi ll be represented at phone (503) 476-2496. the symposium. Len Ramp, Resident Geologist The Saturday evening symposium will be informal Mined land Reciamalion Division: 1129 S.E_ Santiam Road. Albany and devoled to trading, examining dealers' minerals, at· 97321, phone (503) 967-2039. tending microscope and mineral workshops. and Standley L_ Ausmus, Administrator socializing. Additional information about the symposium can Subscription rates: I year, $4_00; 3 years, $10.00. Single issues. be obtained from Mike Groben, RI. I, Box 16, Coos $AO al counler, $.50 mailed. (503) Available bad issues of The Ore Bill: $.25 at counter, $.50 Bay, Oregon 97420; phone: 269-9032. 0 mailed. Address subscription orders, renewals, and changes o f address \0 Oregon Geology, 1069 State Office Building, Portland, OR 97201. ,,,' news, notices, meeting announcements. articles r" pUblication, and editorial correspondence to the editor. Portland office:. The Department encourages author-initiated peer review for technical articles prior to submiss ion_ Any review should be noted in the acknowledgments. CONTENTS Second class postage paid at Portland, Oregon_ Paleomagnetism and age dating of the Ringold PostmaSter: Send address changes to Oregon Geology, 1069 Formation and loess deposits in the State of State Office Building, Portland, OR 97201. Washington. ................ .... ... 119 Ore-Ida to begin geothermal exploration. 133 Locating yourself with the PP&L power pole COVER PHOTO numbering system . .. ..................... 134 White Bluffs, type section of the Ringold Forma· Book review . 136 tion, exposed along Columbia River in southeast· Columbia County No. 1 we ll records for 1977 ern Washinglon. Tht:st: depusits were si udied for 10 be rdeast:d .................. .. .. ..... 136 paleomagnetism_ See article beginning on page Summary of Reichhold drilling in Oregon. .. 137 119. (Photo cou rtesy Duane R. Packer , Wood· New Oregon heat flow publication available ...... 138 ward·Clyde Consultants.) 118 OREGON GEOLOGY, VOL. 4t, NO.II; AUGUST 1919 Paleomagnetism and age dating of the Ringold Formation and loess deposits in the State of Washington by Duane R. Packer, Senior Project Geologist. Woodward-Clyde Consultants, Three Embarcadero Center, Suite 700, San Francisco, California 94/ J I Ho locene. Pleistocene. and Pliocene geologic units in Oregon and Washington commonly display similar lithologies over large areas. Yel , inquiry into the nature of the units is becoming increasingly precise as we probe their meaning in terms of recent faulting and tectonism. Paleomagnetism is one of several technologies now being used to increase our understanding of these units. Woodward-Clyde Consultants , under contracllO the Washington Public Power Supply System, used paleomag­ netic tech niques 10 help establish the age of the Ringold Formation in southeastern Washington and Craigs Hill loess deposits at Ellensburg, Washington. This article describes types of techniques that may be applicable in addressing the poorly understood late Cenozoic geology, both in Washington and in Oregon. All artwork and photographs are courtesy of Woodward-Clyde Consultants. PALEOMAGNETISM polarity of the earth's field. on be used to detect latitudinal move­ which magnetostra tigraph y is ments relati ve to the earth's field. Introductio n based. appear to have occurred ran­ rotations about vertical and hori­ domly in the geologic past and are zomal axes, and relative strati­ Paleomagnetism is a nsefultool recorded in rocks worldwide. Com­ graphic position in the magneto­ for determining the dates of forma­ plete reversals having durations on stratigraphic record. The applica­ tion of sedimentary and igneous the order of 101 years are called tion of paleomagnetic studies that rocks. The application of paleo­ magnetic polarity epochs. Complete has the greatest potential in engi­ magnetism is based on the fact that reversals having durations on the neering geology is based largely on rocks record the direction and inten­ order of 10 1 to 10' years are known magnetostratigraphy, which can be sity of the earth's magnetic field as events. Significant changes in used as a relative age-dating and during their formation and retain magnetic pole positio n, but not stratigraphic correlation tool in this magnetic information fo r thou­ complete reversals, having dura­ detecting and dating possible fault sands to billions of years. The age­ tions on the order of 10 1 years are displacements in time-stratigraphic dating aspect of paleomagnetism called magnetic excursions. horizons. takes advantage of the fa ct that the All of these magnetic phenom­ Individual paleomagnetic po­ earth's magnetic fie ld is dynamic ena have potential for use in dating, larity zones in themselves do not and has undergone a number of dis­ but polarity epochs and some events have unique characteristics that tinctive changes in the geologic past. are the best dated and documented allow identification of, for example, The record of these changes can in geologic sections throughout the an older normal zone from a be used to date geologic materials. world. Other changes in declination younger normal zone. Therefore. The most !!asily recognized of all and inclination (the magnetic azi­ some bracketing age data (paleonto­ these changes is a reversal of the muth and dip, respectively), called logic or radiometric), as we ll as a earth's magnetic field, which has oc­ secular variations. take place on a moderately continuous geologic sec­ curred many times in the geologic continental scale and ha ve durations tion, are usuall y required as a basis 1 history of the earth. The last major of !Ol to 10 years. These chan~e s for identifying the general age of the reversal occurred 700,000 years ago have application (0 dating in paleomagnetic zones. (Figure I). specific geographic areas such as Paleomagnetism is based on the Europe. where the known magnetic characteristic ability of magnetic Theory record over the past several thou­ minerals to record and retain, in sand years includes secular varia­ some cases o n the order of billions The earth's magnetic field un­ tions. In other areas, the secular of years, the magnetic field in which dergoes various changes in both in­ variation pattern could potentially they were formed . This property is tensity and direction over periods of be developed and applied 10 correla­ called natural remane:l( magnetiza­ time ranging from nanoseconds to tion problems. tion (NRM). One way in which mi llions of years. Reversals of the Basically, paleomagnetism can NRM is acquired is by thermal rem- OREGON GEOLOGY. VOL. 41. NO. I. AUGUST 1919 ". > anenl magnetization (TRM). A AGE > ~ (101, 111." AGE' POLARITY magnetic mineral acquires its mag­ VOOl, I • " (Mi11ion Yeor5 ) EVENTS 8 EXCURSIONS netization as it cools through its ~ Curie point, the temperature at .r 0.013 GOTHENBURG EXCURSION which the atomic and molecular '- 0.030!0.005 LASCHAMP " EVENT" - Q. llO:!:O.OO5 BLAKE "EVENT " thermal energy become surricienlly ~ - 0.180:!:0.02 BIWA I "[VENT " low that the spin directions and • magnetic moments become locked ~ - 0 .280:!: 0 .03 BIWA II "EVENT " ,w along the ambient fie ld direction. - 0 .350:1:0.03 BIWA m "EVENT " % Natural remanent magnetization in •=" rocks is also dependent on many other factors. including crystal structure and