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This institution reserves the right to refuse to accept a copying order if, in its judgment, fulfillment of the order would involve violation of copyright law. CALIFORNIA DEPARTMENT OF CONSERVATION DIVISION OF MINES AND GEOLOGY .. 'DMG OPEN-FILE REPORT 83-27 •• I ,z;. __ ~... ..... GEOTIJERMAL -RESOURC_ES OF-- THE-"- ... SOI~'O)MA - NORTHERN. - .. - ..•..----.-.-- --- ..-.--."~.-----. VALLEY ---.... AREA.. - -, .~S01~·-OMA _COlJl~'T-Y,-'CALIFOR~I-~ . 1983 STATE OF CALIFORNIA THE RESOURCES AGENCY DEPARTMENT OF CONSERVATION GEORGE DEUKMEJIAN GORDON K. VAN VLECK RANDALL M. WARD GOVERNOR SECRETARY FOR RESOURCES DIRECTOR OPEN FILE REPOR r 83-27 SAC GEOTHERMAL RESOURCES OF THE NORTHERN SONOMA VALLEY AREA, CALIFORNIA 1983 By Leslie G. Youngs - Engineering Geologist Linda F. Campion - Geologist Rodger H. Chapman - Geophysicist Chris r. Higgins - Geologist Eddie Leivas - Geologist Gordon W. Chase - Geophysicist Stephen P. Bezore - Geologist Under the Direction of C. Forrest Bacon - Geologist California Department of Conservation Division of Mines and Geology 1416 Ninth Street, Room 1341 Sacramento, CA 95814 TABLE OF CONTENTS Page EXECU T I VE S l.Jl\t\\1A.R Y •••••••••••••••••••••••••••••••••••••••••••••••• AB 5 TRACT •••• ...••...•••••••..••••••••••••••••••••••••••.•.•••••••• 3 I NTRODUCT ION ..................•........•.......•.•....•.......... 5 WAR~ SPRINGS IN THE NORTHERN SONQ~ VALLEY AREA ..... 7 Morton's Warm Spring (Los Guilicos Wa rm S p r i n g s ) • 7 The McEwan Ranch Warm Spring .••.• 8 McOo n aid We 1 1 (S p r i n g?) ••••••••••• 8 Spring Lake Park Unnamed Spring .. 8 Co n c 1 u s ion s . • 9 GEOLOGY OF NORTHERN SOl'OW\ VALLEY AND VICINITY, SONO'v\A COUNTY, CALIFORNIA. 1 1 Introduction ..••. 1 1 Pu r po s e ••••..••• 1 1 Previous Studies. 1 1 Present Studies. 1 1 General Geologic Setting ••••••.• 1 2 Geology of Northeast Side of Northern Sonoma Valley. 12 Franciscan Complex and Serpentinite .••.•..•.. 1 2 Sonoma Volcanics .••..• 1 3 Glen Ellen Formation and Overlying Surficial Deposits 13 S t r uc t u re ..••••..••.• 13 Geology of Southwest Side of Northern Sonoma Valley .• 15 Petaluma Formation •• 15 Sonoma Volcanics. 15 Glen Ellen Formation. 16 All u v i a 1 De p 0 sit s ...•....•• 16 S t r uc t ure ••••••••..•.. 1 6 Summary of General Structure of the Main Valley. 18 Influence of Geology on Locations of Thermal Water in Northern Sonoma Valley .••••...•• 20 A Comparison of Northern and Southern Sonoma Valley Geology •. 2 1 Geog r aphy .••• 21 Strat igraphy .. 21 Structure •••.•. 22 GEOPHYSICAL INVESTIGATIONS .. 23 Introduction •••••••.••. 23 iii Page Gravity Survey •...•...•........•.... · . ., . 23 Pu r pose ••••••••.••••••••..••••• ·. 23 Equipment and Field Procedure •• 23 Gravity Data ..•.••..•.......... 24 Interpretation of Gravity Data. .. · . 24 Magnetic Surveys. 37 Purpose •••••• .. 37 Aeromagnetic Data •• . · . 38 Equipment and Procedure for Ground Survey •• · . 38 Interpretation of Ground Magnetic Data •• · . 38 Electrical Resistiyity Surveys •••••• . .. · .... 40 Purpose •••••• . 40 Equipment and Field Procedure •• 44 Interpretation of Resistivity Data •• . .. · .... 44 Conclusions and Recommendations •••••••••• · . 46 SEISMICITY OF THE NORTHERN SONOMA VALLEY AREA.................... 49 SHALLOW TEMPERATURE PROBE SURVEy................................. 53 HYDROL<:x:iY. • • • • • • • • • • • • • • • • • . • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 5 5 GEOCHEMISTRY. ...... 57 Introduction •• · . 57 Methodology •••••••••• . .. ..... 57 Results .•.•. 57 Conclusions ••• . 58 GEOTHER~TRY •••• . .. .. · .. · . 61 Introduction. 61 Methodology. 61 Results 6·2 Conclusions. 67 DIRECT THERMAL TEMPERATURE MEASUREMENTS IN THE SONOMA VALLEY AREA •.•••• · . 69 Introduction •• 69 Methodology. 69 Re sui t s ..••• .' .. 69 Conclusions. 87 GENERAL ASSESSMENT OF THE LOW-TEMPERATURE GEOTHERMAL RESOURCES IN THE NORTHERN SONQ~ VALLEY AREA. 89 Introduction ..• 89 Areal Distribution •. 89 Depth of Resource ••.. 92 Volume of Geothermal Resources. 92 Temperature of Geothermal Resources. 93 Resource Chemistry •• 93 Reservoir Model •••• 94 iv Page CONCLUS IONS AND RECO'vMENDA T IONS. • . •. • • . • • . • . • • • . • • . 97 Conclusions .................................................. 97 Recornnenda t ion s • • • . • . • • • • . • • • . • • . • . • • . • • • • . • • • • • • • • • • • . • • 98 ACKNO'WL EOCEMEN T 5 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 9 9 SELECTED BIBLIOGRAPHY INCLUDING REFERENCES CITED FOR THE NORTHERN SONOMA VALLEY AREA, CALIFORNIA .•.•......•... 101 v LIST OF TABLES Page Table 1. Earthquakes in the Sonoma Valley area from 1 8 0 0 - 1 9 7 4. • . • • . • . • • • • • . • . • • • . • . • • • • • • • • • 50 Tab 1 e 2. Geothermometry temperature (OC) values for selected water wells and springs in the Sonoma Valley area California •••••••••••••••••••• 63 Table 3. Direct temperature measurements of selected geothermal wells and springs ( Temp era t u r e 2.. 2 0 ° C) i nth e Son oma Valley area, California •••••••••••••••••••••••••••••• 70 LIST OF FIGURES Page Figure 1. S tat e we lin umb e r i n g s y stem. • • • • • • • • • • • • • • • • • • • • • • • • • 6 Figure 2. Diagrammatic section across northern Sonoma Valley........................................ 19 Figure 3. Line KB-KB', showing gravity and magnetic profiles, Northern Sonoma Valley area •••••••••••••••• 25 Figure 4. Line KC-KC'-KC", showing gravity and magnetic profiles, Northern Sonoma Valley area •••••••••••••••• 26 Figure 5. Gravity profiles KG-KG' and KC'-KC", Northern Sonoma Valley area ...•.............................•. 27 Figure 6. Line KD-KD' , showing gravity and magnetic profiles, Northern Sonoma Valley area •••••••••••••••• 28 Figure 7 • Line KE-KE', showing gravity and magnetic pro f i 1e s, No r the r n Son oma Valle y are a • • • • • • • • • • • • • • • • 2 9 Figure 8. Lines KF-KF' and KH-KH', showing gravity and magnetic profiles, Northern Sonoma Valley area.. .......... ...... ..... ...................... .... 30 Figure 9. Gravity profile SA2-SA2', Northern Sonoma Valley............................................... 31 Figure 10. Gravity profile SA3-SA3', Northern Sonoma Valley area......... .................. ............... 32 Figure 11. Gravity profile SA7-SA7', Northern Sonoma Valley area......... ................................. 33 vi Page Figure 12. Gravity profile SA8-SA8', Northern Sonoma Valley area.......................................... 34 Figure 13. Residual gravity profile and interpretation, Northern Sonoma Valley area.......................... 36 Figure 14. Magnetic susceptibility of drill cuttings from Sonoma State Hospital well no. 3, Sonoma County, California. 39 Figure 15. Magnetic profiles M2-M2' and M3-M3', northern Sonoma Valley area.......................... 41 Figure 16. Magnetic profiles M~E-ME' and MF-MF', nor the r n Son oma Valle y are a . • • • . • • • • • • • • • • • • • • • . • • • • • 4 2 Fig u rei 7 • Ma g net i cpr 0 f i 1 e s MG -MG ' and MI -M I ' , nor the r n Son oma Valle y are a • • • • • . • • • • • • • • • • • • • • . • • . • • 4 3 Figure 18. Schlumberger sounding VES-3 and interpretation, nor the r n Son oma Valle y are a . • • • • • • • • • • • • • • • • • • • • • • • • • 4 5 Figure 19. Location of shallow temperature probe holes.......... 54 Figure 20. Boron concentration in groundwater in the Sonoma Valley area, California....................... 59 Figure 21. Total dissolved solids (TDS) concentration in groundwater in the Sonoma Valley area, California.... 60 Figure 22. Temperature Log - Location No. t ••••••••••••••••••••• 74 Figure 23. Temperature Log - Location No. 2 • . • • • • • • • • • • • • • • • . • • • 75 figure 24. Temperature Log - Location No. 3. • • • • • • • • • • • • • • • • • • • • 76 figure 25. Tempera tur.e Log - Location No. 4 ••••••••••••••••••••• 77 figure 26. Temperature Log - Location No. 23 •••••••••••••••••••• 78 figure 27. Temperature Log - Location No. 29. • . • • . • . • • . • • 79 figure 28. Temperature Log - Location No. 39 •••.••••••••••••••••• 80 Figure 29. Temperature Log - Location No. 44. • . • • . • . • . • . • . • . 81 Figure 30. Temperature Log - Location No. 50 ••.••.•••...•••.•••• 82 figure 31. Temperature Log - Location No. 5 1 •••••••••••••••••••• 83 figure 32. Temperature Log - Location No. 59 •••••••••••••••••••• 84 figure 33. Temperature Log - Location No. 92 ... .................. 85 vi i Page Figure 34. Temperature Log - Location No. 122................... 86 Figure 35. Temperature ranges of some possible geothermal