Geology of the Republic Quadrangle and a Part of the Aeneas Quadrangle Ferry County, Washington By SIEGFRIED MUESSIG GEOLOGICAL SURVEY BULLETIN 1216 Geology of an area in northeastern Washington that contains important gold^ silver deposits and a major structural feature, the Republic graben UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1967 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY William T. Pecora, Director Library of Congress catalog-card No. OS 67-178 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 CONTENTS Page Abstract__ _ _____________________________________________________ 1 Introduction. _____________________________________________________ 2 Location and culture_________________________________________ 2 Physical features.__-_____-_____-_-___-_-___-_____-__________-- 4 Climate and vegetation_______________________________________ 6 Fieldwork and acknowledgments._______________________________ 7 Scope of the report.___________________________________________ 9 Geologic sketch of the area.________________________________________ 9 Metamorphic rocks east of Sherman fault___________________________ 11 Permian rocks___-_-_---__--_---___--_-__-__--___-_-_--_________ 12 Lithology and petrography.____________________________________ 13 Mafic tuff, lava, and associated intrusives____________________ 13 Argillite and graywacke____________________________________ 17 Limestone._ ______________________________________________ 19 Conglomerate.____________________________________________ 24 Quartzite and chert__-__-_-___-__--_-_______-__.___________ 25 Marble_.___________...___._____.____.._ 26 Origin__._____^_.___._.._.__.____..._-_______..______._____. 26 Age and correlation____________-__-_____-____-___--_-__________ 27 Grade of metamorphism______________________________________ 28 Upper Paleozoic(?) rocks near Sheep Mountain______..___-__._-__._- 28 Marble__---_______________.______--__________--________--.__- 29 Dark siliceous marble.____-____-__-__-_-_______._______..___-__ 30 Schist and phyllite___--.._..___-____.____________ 32 Amphibolite. __-_-_________________-_..--.________--______-_____ 34 Age and correlation of the layered rocks..________________________ 35 Metamorphic rocks near Golden Harvest Creek____.____.____._____.._ 35 Lithology and petrography---------------.---------^----------- 35 Origin .--_-_--- -----___-..__________._._.__....._... 37 Age and correlation.._______..___.____________..-_-_________..- 38 Relations among upper Paleozoic rocks in this area___-_---_-.-__------ 38 Cretaceous batholith.--____-_----.--_--------___-___-_-_-_-__--_--- 39 Name and distribution._-_-___--- i -_---___-_-___--_--____------ 39 Relations to other rocks.._____-..__---_--____-___-__--_-----_-_- 40 General character and lithology---_---__--__--____--__--_---_--- 40 Age and correlation.__-__--_________--____--__-_-_-_---_-----_- 42 Unconformity at the base of the Tertiary rocks-__-___--_-__--_---_--- 43 Tertiary rocks______-___-_----__--_--__-----_---_---__--__----_- 44 Diorite.-__-__-____-__._--__.-___-____--_--_-_----____-_------ 45 O'Brien Creek Formation_____________________________________ 45 Definition ________________-__-___-_--__-_-_---_-_--_------ 45 Distribution and thickness.._____-_---_-_-_-----__--_------- 46 Lithology_ _______.__._._____--.____-.-_-.---__---------- 47 Relation to Sanpoil Volcanics._____-_____--____--_---------- 48 Conditions of sedimentation-..-------.--------------------- 49 Age and correlation...__-.________-_-___-------__---------- 49 in IV CONTENTS Tertiary rocks Continued Page Sanpoil Volcanics._____________________________________________ 50 Distribution and thickness__-_----_---_-__-_-_--_______-____ 51 Lithology and petrography__ -__--__-__-_____-_--___________ 51 Age and correlation._______________________________________ 54 Scatter Creek Rhyodacite_--_______-________--_-______^________ 54 Definition ________________________________________________ 54 Distribution. ___-_---__-___________ _______________________ 54 Lithology and petrography _________________________________ 55 Relations to Sanpoil Volcanics and O'Brien Creek Formation. _ 57 Age and correlation.__--____-___-_---___---_-_--__________- 58 Quartz monzonite of Herron Creek_____________________________ 58 Outcrop area and relation to other rocks_________-_____-_-_. 58 Lithology and petrography. ________________________________ 58 Age and correlation.--_--___--_-____________-_-_-____-__-__ 60 Quartz latite porphyry_________________________________________ 61 Quartz monzonite east of Sherman fault-_________________________ 62 General features and petrography ___________________________ 62 Comparison with rocks of Cretaceous batholith______________ 65 Age and correlation._---_-_-_-___________-____---__________ 66 Unconformity at the base of and within the Klondike Mountain Formation._----_____-__-_-_-_-_________________-___________ 68 Klondike Mountain Formation._-_----__-____________--______-_- 70 Definition______________________________________________ 70 Distribution and thickness..________________________________ 71 Tom Thumb Tuff Member_--_--__-___--_------__________ 71 Middle member.__________________________________________ 73 Basalt member..__________________________________________ 73 Undivided Klondike Mountain Formation________-______--_-- 74 Age. -_-_-----__----- _-__--_-_--_--------_--------------_- 74 Intrusive rocks of uncertain relative ages.____________________________ 75 Granophyric quartz monzonite._____-__________-___---___---___- 75 Trachyandesite dikes and sills..__________________----________--- 76 Aphanite dikes.----__-_-_--____-_______________--_____-__-_--- 77 Quaternary deposits.._-___-_-_--_______--___-_______----__-__-__--- 78 Notes on drainage development________--_____-_--_--__--__----_ 78 Glaciofluvial deposits__________________________________________ 81 Morainic deposits._____________________________________________ 83 Alluvium.____________________________________________________ 83 Structure.---.-------....____--____----____-_-----------------_--- 83 Deformation and metamorphism of the upper Paleozoic (?) rocks on the southwest side of the Republic graben-_____-___-_------_--- 84 Structure of the upper Paleozoic (?) rocks near Sheep Mountain. _. _ _ 88 Structure of the Permian rocks._____________-____-----_-_--_---- 89 The Republic graben and its marginal faults.___._____-_--_--_-_-- 90 Sherman fault____---_______--__-___------ --------------- 90 Bacon Creek fault_______-____________-_-_____--__--_------ 91 Scatter Creek fault zone__-__________---_--__---_-_------- 93 Graben development and Tertiary deposition.___---------_--- 95 CONTENTS V Structure Continued Page Faults within the Republic graben..____-_-__.-___-______._____._ 97 High-angle faults of north trend.____________________________ 97 Faults older than the Lambert Creek thrust ______________ 97 Faults younger than the Lambert Creek thrust.___________ 99 Curved faults east of Curlew Lake.______________________ 101 Short faults west of Republic district vein system.________ 102 Faults just east of Republic___________________________ 102 Faults recognized only on aerial photographs..____________ 102 Fault zone along the Republic district vein system.____________ 103 High-angle faults of east trend.__-_-_----____-_-___-____._-. 105 Lambert Creek thrust------------_---------_-------_-_---_- 107 The Sanpoil syncline.__________________________________________ 110 Mineral deposits..________________-_-_____-----._______.__.___.____ Ill Deposits in upper, Paleozoic rocks.._______________________________ 112 California mine--_-_____-__----__--_-_-_-___-_---_______.__ 112 Belcher group of mines_-----------------_------------_---_- 112 Gold-silver deposits in Tertiary rocks____-_--_____---_-_-___.____ 114 Valley mine.j..___________------_--________________________ 114 Republic district vein system_______________________________ 114 Summary of history and production._____________________ 115 General features of the veins.___________________________ 117 Alteration of the country rocks.._____-_______-_-___---__ 120 Age of mineralization. _________________________________ 120 Structural setting and control of the veins ________________ 121 Outlook for exploration----__-------_____-----_-_-_----- 123 Geologic history.__________________________________________________ 123 References cited._______--______-_-____----_________----___-__--_-_ 127 Index....__________________________._____-__-__-___---_---___---_- 133 ILLUSTRATIONS PLATE 1. Geologic map and sections of the Republic and a part of the Aeneas quadrangles, Ferry County, Wash.._-In pocket Page FIGURE 1. Index map_______________ _________________________ 3 2. Aerial view of area east of Republic..-.---------------- 5 3-10. Photograph of 3. Phyllite .---.-..-_---------__---_---__-_-- 15 4. Graywacke________________________________ 18 5. Contorted schist showing pencil structure. ____-- 33 6. Characteristic specimen of O'Brien Creek For- mation__ _ ________________________________ 47 7. Typical Scatter Creek Rhyodacite__-____-_-_ 55 8. Fine-grained quartz monzonite.______________ 59 9. Typical medium-grained quartz monzonite from east of the Sherman fault from near its northern end______________________---__ 65 10. Typical medium-grained quartz monzonite from east of the Sherman fault..______-___-_---_- 66 VI CONTENTS Page FIGURE 11. Triangular diagram showing relative amounts of the major