-frf fti IVNO'ISSX.JQH<I Hydrothermal Systems of the Cascade Range, North-Central Oregon By S.E. INGEBRITSEN, R.H. MARINER, and D.R. SHERROD GEOHYDROLOGY OF GEOTHERMAL SYSTEMS U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1044-L UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1994 U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY Robert M. Hirsch, Acting 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. Library of Congress Cataloging-in-Publication Data Ingebritsen, S.E. Hydrothermal systems of the Cascade Range, north-central Oregon / by S.E. Ingebritsen, R.H. Mariner, and D.R. Sherrod. p. cm. (Geological Survey professional paper ; 1044-L) (Geohydrology of geothermal systems) Includes bibliographical references. Supt. of Docs, no.: I 19.16:1044-L 1. Geothermal resources Cascade Range. 2. Geothermal resources Oregon. I. Mariner, R.H. II. Sherrod, David R. III. Title. IV. Series. V. Series: Geohydrology of geothermal systems. GB1199.7.07I54 1994 551.2'3'09795 dc20 94-3127 CIP For sale by USGS Map Distribution, Box 25286, MS306 Denver Federal Center, Denver, CO 80225 CONTENTS Page Page Abstract.......................................................................................... LI Thermal waters Continued Introduction................................................................................... 1 Heat transport....................................................................... L34 Purpose and scope................................................................. 2 Conductive heat flow.................................................................... 35 Previous investigations ........................................................ 2 Conductive heat-flow map ................................................... 36 Acknowledgments.................................................................. 4 Area of low-to-zero near-surface heat flow........................ 40 Geologic setting............................................................................. 4 Areas of high conductive heat flow.................................... 41 Stratigraphy.......................... ............................................. 5 Heat budget................................................................................... 41 Structure................................................................................. 8 Conceptual models........................................................................ 44 Quaternary extrusion rates................................................. 9 Implications of regional gravity, magnetic, and Hydrologic setting......................................................................... 10 electrical geophysical data............................................... 44 Precipitation........................................................................... 10 Testing the conceptual models............................................ 48 Stable-isotope data................................................................ 10 Numerical simulations................................................................. 49 Ground-water recharge estimates ...................................... 16 Permeability structure .................: ..................................... 50 Nonthermal ground-water chemistry ................................ 18 Breitenbush section .............................................................. 50 Thermal waters............................................................................. 24 McKenzie River section........................................................ 59 Location of hot springs......................................................... 24 Heat transfer rates and residence times .......................... 65 Stable-isotope data................................................................ 26 Comparison with other volcanic-arc areas ............................... 65 Thermal-water chemistry .................................................... 28 Summary........................................................................................ 66 Geothermometry.................................................................... 29 References cited ............................................................................ 67 Residence times ..................................................................... 30 Appendix: Conductive heat-flow data...................................... 73 Hot-spring discharge rates .................................................. 31 ILLUSTRATIONS [Plates are in pocket] PLATE 1. Generalized map of the Cascade Range, north-central Oregon, showing deuterium data. 2. Generalized geologic map of the Cascade Range, north-central Oregon, showing conductive heat-flow data. Page FIGURE 1. Map showing location of study area............................................................................................................................................. L3 2. Map showing generalized setting of Cascade volcanic arc in Washington and Oregon and extent of Quaternary volcanic deposits .......................................................................................................................................................................... 5 3. Generalized geologic map of Cascade Range and adjacent areas of north-central Oregon between latitudes 44° and 45°15' N. ................................................................................................................................................................................ 6 4. Map showing average annual precipitation in and near study area and areas for which ground-water recharge is estimated ....................................................................................................................................................................................... 11 5. Graph showing relation between deuterium and oxygen-18 contents for waters sampled in and near study area....... 12 6. Graph showing relation between deuterium content and elevation for waters sampled in and near study area.......... 12 7. Map showing surficial geology and location of streamflow-gaging stations in basins for which ground-water recharge was estimated .............................................................................................................................................................. 16 8. Hydrographs for major streams in basins for which ground-water recharge was estimated ............................................. 17 9. Trilinear diagram showing chemical analyses of nonthermal ground waters and hot springs ......................................... 19 10. Map showing sodium concentrations in waters sampled in and near study area ................................................................ 23 11. Map showing location of hot springs, generalized topography, selected geologic structures, Quaternary volcanic rocks, water-table elevations in Deschutes basin, and amount of heat transported advectively by hot-spring systems ......................................................................................................................................................................................... 25 12. Graph showing relation between deuterium content and elevation for waters on or west of Cascade Range crest...... 26 13. Graph showing calculation of hot-spring discharge with solute-flux methods...................................................................... 34 14. Graph showing temperature-depth profiles from heat-flow sites 13, 38a, 79a, and 85....................................................... 36 15. Graph showing temperature-depth profiles from relatively deep drill holes in study area ............................................... 36 16. Maps showing conductive heat-flow contours ............................................................................................................................ 40 17. Graph showing temperature-depth profiles from drill holes collared in rocks older than 7 Ma in Breitenbush Hot Springs area.......................................................................................................................................................................^ 41 18. Conceptual models of thermal structure of the north-central Oregon Cascades .................................................................. 45 19. Graphs showing relation between heat flow and gravity data ............................................................................................... 46 in IV CONTENTS Page FIGURE 20. Map showing relation between near-surface heat flow, Curie-depth boundaries, and deep-crustal electrical conductor .........................................................................................................................................................................^ L47 21. Graph showing relation between spring temperature and elevation ................................................................................... 49 22. Map of Breitenbush Hot Springs area showing thermal and nonthermal mineral springs, Quaternary volcanic rocks, electrically conductive zones, and 100°C contour.................................................................................................... 52 23. Generalized lithologic section used for numerical simulation of Breitenbush Hot Springs system ............................... 53 24. Diagrams