U.S. Department of the Interior U.S. Geological Survey Hydrothermal Mineralogy of Core from Geothermal Drill Holes at Newberry Volcano, Oregon Professional Paper 1578 Hydrothermal Mineralogy of Core from Geothermal Drill Holes at Newberry Vo l c a n o , O r e g o n KEITH E. BARGAR AND TERRY E. C. KEITH U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1578 UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1999 DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY Charles G. Groat, Director Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government. Manuscript approved for publication, April 20, 1997 Text and illustrations edited by Jeff Troll Library of Congress Cataloging-in-Publication Data Bargar, Keith E. Hydrothermal minerology of core from geothermal drill holes at Newberry Volcano, Oregon / Keith E. Bargar and Terry E.C. Keith. p. cm -- (U.S. Geological Survey professional paper ; 1578) Includes bibliographical references. Supt. of Docs. no.: I 19. 16: 1578 ISBN 0-607-91905-1 1. Hydrothermal alteration--Oregon--Newberry Volcano Region. 2. Minerals--Oregon--Newberry Volcano Region. 3. Geothermal resources--Oregon--Newberry Volcano region. I. Keith, Terry E.C. II. Title. III. Series. QE390.5.B375 1999 551.2'3'09795--dc21 99-32015 CIP For sale by U.S. Geological Survey, Map Distribution Box 25286, MS 306, Federal Center Denver, CO 80225 CONTENTS Abstract---------------------------------------------------------------------------------- 1 Introduction------------------------------------------------------------------------------ 2 Analytical methods---------------------------------------------------------------- 4 Acknowledgments----------------------------------------------------------------- 6 Geologic setting------------------------------------------------------------------------- 6 Geothermal exploration---------------------------------------------------------------- 7 Drill holes within the caldera---------------------------------------------------- 7 USGS-N2-------------------------------------------------------------------- 7 Lithology------------------------------------------------------------ 8 Hydrothermal alteration------------------------------------------------- 8 Surface to 320-m depth--------------------------------------------- 8 320- to 697-m depth------------------------------------------------- 9 697-m to 932-m depth---------------------------------------------- 12 Fluid inclusions----------------------------------------------------------- 16 RDO-1----------------------------------------------------------------------------- 22 Lithology----------------------------------------------------------------- 22 Hydrothermal alteration------------------------------------------------- 23 Fluid inclusions----------------------------------------------------------- 23 Drill holes outside the caldera---------------------------------------------------------- 24 GEO-N1---------------------------------------------------------------------------- 24 Lithology------------------------------------------------------------------ 24 Hydrothermal alteration------------------------------------------------- 26 GEO-N2---------------------------------------------------------------------------- 27 Lithology------------------------------------------------------------------- 28 Hydrothermal alteration------------------------------------------------- 28 Fluid inclusions----------------------------------------------------------- 30 GEO-N3---------------------------------------------------------------------------- 30 Lithology------------------------------------------------------------------- 30 Hydrothermal alteration-------------------------------------------------- 32 GEO-N4----------------------------------------------------------------------------- 32 Lithology------------------------------------------------------------------- 32 Hydrothermal alteration-------------------------------------------------- 32 GEO-N5----------------------------------------------------------------------------- 32 Lithology------------------------------------------------------------------- 33 Hydrothermal alteration-------------------------------------------------- 33 SF NC-01--------------------------------------------------------------------------- 35 Lithology------------------------------------------------------------------- 35 Hydrothermal alteration-------------------------------------------------- 35 Fluid inclusions----------------------------------------------------------- 36 SF NC72-03------------------------------------------------------------------------ 38 Lithology------------------------------------------------------------------- 38 Hydrothermal alteration-------------------------------------------------- 38 Fluid inclusions----------------------------------------------------------- 39 Other drill holes-------------------------------------------------------------------- 40 Hydrothermal mineralogy of drill core specimens----------------------------------------- 41 Drill holes within the caldera------------------------------------------------------------ 41 Drill holes outside the caldera----------------------------------------------------------- 41 Hydrothermal minerals------------------------------------------------------------------------- 42 V VI CONTENTS Zeolite minerals-------------------------------------------------------------------- 42 Analcime--------------------------------------------------------------------- 42 Chabazite--------------------------------------------------------------------- 43 Clinoptilolite----------------------------------------------------------------- 44 Dachiardite ------------------------------------------------------------------ 44 Erionite----------------------------------------------------------------------- 45 Faujasite---------------------------------------------------------------------- 45 Heulandite-------------------------------------------------------------------- 45 Laumontite------------------------------------------------------------------- 45 Mordenite--------------------------------------------------------------------------- 46 Phillipsite--------------------------------------------------------------------------- 46 Calcium silicate hydrate minerals------------------------------------------------------ 47 Gyrolite------------------------------------------------------------------------------ 47 Okenite------------------------------------------------------------------------------ 47 Carbonate minerals---------------------------------------------------------------------- 48 Ankerite-dolomite----------------------------------------------------------------- 49 Aragonite---------------------------------------------------------------------------- 50 Calcite------------------------------------------------------------------------------- 50 Kutnohorite------------------------------------------------------------------------- 51 Magnesite--------------------------------------------------------------------------- 51 Rhodochrosite---------------------------------------------------------------------- 51 Siderite------------------------------------------------------------------------------ 52 Clay minerals------------------------------------------------------------------------------ 53 Kaolinite and halloysite----------------------------------------------------------- 53 Smectite----------------------------------------------------------------------------- 54 Mixed-layer illite-smectite-------------------------------------------------------- 56 Illite---------------------------------------------------------------------------------- 56 Mixed-layer chlorite-smectite---------------------------------------------------- 57 Chlorite------------------------------------------------------------------------------ 58 Silica minerals----------------------------------------------------------------------------- 59 Opal---------------------------------------------------------------------------------- 59 Cristobalite-------------------------------------------------------------------------- 59 Quartz and chalcedony------------------------------------------------------------ 60 Sulfide minerals--------------------------------------------------------------------------- 62 Pyrrhotite---------------------------------------------------------------------------- 62 Pyrite-------------------------------------------------------------------------------- 63 Marcasite---------------------------------------------------------------------------- 64 Sphalerite--------------------------------------------------------------------------- 65 Sulfate minerals--------------------------------------------------------------------------- 65 Anhydrite--------------------------------------------------------------------------- 65 Barite-------------------------------------------------------------------------------- 66 Jarosite, natroalunite, and natrojarosite----------------------------------------- 66 Gypsum----------------------------------------------------------------------------- 67 Iron oxide and iron hydroxide minerals------------------------------------------------ 67 Hematite and lepidocrocite------------------------------------------------------- 67 Goethite----------------------------------------------------------------------------- 67 Magnetite--------------------------------------------------------------------------- 68 Amorphous iron oxide------------------------------------------------------------