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Geology and Mineral Deposits Loomis Quadrangle

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Geology and Mineral Deposits Loomis Quadrangle STATE OF WASHINGTON DEPARTMENT OF NATURAL RESOURCES BERT L. COLE, Commissioner of Public Lands DON LEE FRASER, Supervisor I =================================== DIVISION OF MINES AND GEOLOGY VAUGHN E. LIVINGSTON, JR., State Geologist Bulletin No. 64 GEOLOGY AND MINERAL DEPOSITS OF THE LOOMIS QUADRANGLE, OKANOGAN COUNTY, WASHINGTON By C. DEAN RINEHART and KENNETH F. FOX, JR. Prepared cooperatively by the UNITED STATES GEOLOGICAL SURVEY $TATE PRINTIN(; PL.ANT~ OLYMPIA, WASHINGTON 1972 For sale by Deportment of Natural R\'.'SOurCl!S, Olympia, Washington. Price $4.00 CONTENTS Page Abstract ........................ ............... , ....... ............. ................... Introduction ...... ... ........ ......... ... ................. ........ ........ .... 3 Fieldwork ................................................................ ............ 3 Previous work and acknowledgments .......... .................. ..... ..... ....... .. 3 Regional geologic setting .......... ....................................................... .. 4 Metomorph i c rocks . ............................. , . ....... ....... ..... ............. 4 Pl uton i c rocks .... ... ..... ............................................ ..... .... 4 Tertiary sedi mentory and igneous rocks .. .................... .... ........ .. .... .. ... 5 Tectonic setting ...................................................... ......... ....... 5 Sketch of local geologic history . .................................. ....................... 6 Stratigraphy of the metamorphic rocks ................... .. ........ .......... ........ ......... 6 General features ... .. .. .................... .. .................... ............. .. 6 Order of superposition . ........ ...................... ......................... ....... 6 Nomenclature ................................... .................. .... ........ .... 7 Redefinition of Anarchist Series and Kobau Group ....................................... ..... 8 Anarchist Group ................. ..... ........ ........... ....................... 8 Spectacle Formation ...... ...................... ................................. 8 Bullfrog Mountain Formation ... ....................... .......................... 10 Sedimentation ................. ......................... ......... ............ 11 Palmer Mountain Greenstone ............................ ... ...... ....... ..... 11 Petrogrophy .................................... ................................. 18 Origin and age ......................................... ..................... ... 18 Mafi c intrusive rocks ..... .............. ............................................ 19 Petrography ................... ....................... ........................ 19 Specific gravity and chemical composition of the mafic intrusive rocks and the Palmer Mountain Greenstone .............................. .......... ............. .... 20 Kobau Formation . ......................... .. ... .. ......... ...................... 20 Lithology................... .................................................... 21 Basal contact and thickness .......... .............................................. 22 Age ............ ......... ..... ....... .•..................................... 22 Ill CONTENTS Stratigraphy of the metamorphic rocks-Continued Page El lemeham Formation ...... .................. ............... ..................... .. .. 22 Lithology and stratigraphy ....... ............. ................................•... 23 Metamorphism ...............................................................•... 23 Age .................... ............. .. .................... .................. 24 Plutonic rocks ............................................................................. 25 Serpenti ni te ........... ...... ............. ....................................... 43 Whisky fvlcuntain pluton ............................................... ...... ......... 43 Loom is pl uton . ... .......... .... ................................ .................... 44 Contacts ....................................... ...... ......................... 45 Compositional zoning ............................................................. 46 Petrochemistry .......... .... ................................................. 46 Age ............. .................... ..... .................. ...... .......... 46 Anderson Creek pluton .......................... ....... ............... ............... 47 Toots Coulee pluton ...... ...................... .... ................................. 49 Contacts and border phase .................. ......................... ........... 49 Petrochemistry ........... ... ......................... ......... ... ............... 51 Age ........................................................................... 51 Similkameen composite pluton ........................................... ... ............ 52 Quartz monzonite-granodiorite .................................................... 53 Pyroxenite, malignite, and syenite gneiss ........ ........................... ........ 54 Greisen, aplite, and alaskite ................................ ...................... 54 Petrographic trends ................................ ......... .... .............. .. 55 Petrochemistry ........................................... .... ... ............. .. 56 Origin and age .......... .. .................. .............................. ... 56 Petrologic summary of the plutonic rocks ................................................•.. 56 $hankers Bend diatreme ..................................................................•.. 58 Intrusive rocks in dikes and small masses ......................................................•.. 59 Rocks of Tertiary age .. .................... .............................................•.. 59 Sedimentary rocks ..................................................................•.. 59 Conglomerate and arkose ........... ............ ... ........................... ... 60 Volcanic graywacke .................... ......................................... 60 JV CONTENTS Rocks of Tertiary age-Continued Page Sedimentary rocks-Continued Age ........ ... .. ............................. ..... .. .................. 61 Interpretation of Tertiary sedimentation ........ ... .. ... ... .. .. .. ............. 62 Igneous rocks .......... ... ... ................................. ............. ...... 62 Li tho logy . • . 62 Age . ......... ........ ... .. ...................... ... .. .... ......... 62 Metamorphism . ... .. ..... ...................... .. ............ ...... ......... 63 Anarchist Group and Kobou Formation ................... .......................... ...... 63 Ellemehom Formation .......... ....... .... .....• . ................ ..... .......... .. 64 Structural geology ....................... ..•............... .......... ....... ..... 65 f.Aajor folds ... ............ .......... ... .... ................ ............. .•. 66 Wonnocut Lake area ......................... .. ..... .... ............. , .... 66 Chopoko and Grandview f.Aauntoin areas ........ .. ................. ................• 66 Cayuse f.Aauntoin area ................................ ....... ........ ....... 67 Minor folds and crenulotions ............................................ .. ........... ... 69 Pre-Tertiary faults and lineaments ... .................. ......... ............. .... 70 Chopoko-Aeneos lineament ......................... .......... ........ ... ..... 70 Gold Hill fault ........ ........ ..... .......... ..... ..... ..... ........ 70 Cayuse f.Aauntoi n thrust fault . .......................... ......... .... .............. 71 Tertiary warping and faulting ..•.................. ....... ................. ...... ..... 72 Interpretation of the structural record ........ ................ ... ........ .7 . ........ 72 / Physiography and glaciation . ............. ............................................... 72 Chopoko f.Aauntoin landslide threat ........................ ................. ............. 76 Minero I deposits ................... .................... ......................... .......• 77 Metallic deposits ............... ......................... ........................... 77 Vein deposits ........................................................... ....... 77 Magmatic deposits ........ ................... ....... ....... ... .. ...... 120 Placer deposits ......................................................... ........ 120 Nonmetallic deposits ........ .................. ............. ... ......... ......... 120 Limestone . 1 20 Gypsite ........ ...... .... ............................................. ...... 121 References cited ....... .......................... ... ..................................... 122 V CONTENTS ILLUSTRATIONS Plate l. Geologic map and sections of the Loomis quadrangle ............ ...... .... In pocket 2 . Map showing mineral deposits of the Loomis quadrangle, Washington .......... ... In pocket Page Figure l. Index map of Washington showing location of the Loomis quadrangle .... ..... ......... 3 2. Stratigraphic nomenclature of rocks of the Loomis quadrangle .................... ....... 7 3. Specimen of distinctive chert-bearing conglomerate common to both the Spectacle and Bullfrog Mauntain Formations . ....... , .. .... , , . , , ...... , ... .......... 9 4. Amygdaloidal Palmer Mauntain Greenstone from near the eastern contact of the formation on Palmer Mauntain ... ......... ...... .................. ....... 11 5. Graphs showing
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