June 1980 Alaska Open-File Report 127 ASSESSMENT OF THERMAL SPRINGS SITES IN SOUTHERN SOUTHEASTERN ALASKA---PRELIMINARY RESULTS AND EVALUATION BY Roman J. Motyka, Mary A. Moorman, and John W. Reeder CONTENTS Abstract - - - - - - - - - - - - - - -. - - - - - - - - - - - - - - - - i Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1 Ilse of the report- - - - - - - - - - - - - - - - - - - - - - - - - - - 2 Hydrothermal convective systems- - - - - - - - - - - - - - - - - - - - 4 Field techniques and sampling procedures - - - - - - - - - - - - - - - 5 Lnhoratory aonly~es:Methodr used and precision- - - - - - - - - - - - h Gpotl1~>r~~(~~~etry- - - - - .- - - - - -- - - - - - - - - - - - - - - -- - - 0 Silica gpotllprmometzy - - - . -- - - - - - - - - - - - - - - - - - 10 Silica mixingmodels- - - .- - - -. - - - - - - - - - - - - - - - - 12 Sodium-potn~;sirlm-cali.ium gcott~errnornet-ry- - - - - - - - -- - - -- - 1 3 Accur- icy oi grotl~ermometry- - - - - - - - - - - - - - - - - - - -- 15 Descl ipl ion oL individ~~altherrni~l-spring sites - - - - - - - - - - - - I6 1. (:hi& Shalces hot c;prings - - - - - -- - - - - - - - - - - -- - - 18 2. Harnes Lake (paradise) warm springs- - - - - - - - - - - - - - 24 3. Fowler Hot Springs (Canada)- - - - - - - - - - - - - - - - - - 2 8 4. Twin Lakes (West Shakes) warm springs- - - - - - - - - - - - - 33 5. Mt. Rynd~(South tik kine), reported warm spring- - - - - - - - 3 7 6. Vank Island, reported hot sprlng, unsubstantiated- - - - - - - 38 7. Virginia Lake, reported hot spring, unsubstantiated- - - - - - 39 8. Bretlfic>id hot qprings-- - - - - - - - - - - - - - - - - - - - 40 9. Bell Island hot springs- - - -- - - - - - - - - - - - - - - - - 44 10. Bailey Ray Hot Springs - - - - - - - - - - - - - - - - - - - - 5 1 11. Saks, reported hot springs, unsubstantiated- - - - - - - - - - 5 9 12. Unuk, reported thermal springs, unsubstantiated- - - - - - - - 60 13. Raker Island Hot Springs - - - - - - - - - - - - - - - - - - - 6 1 Summary, southern Southeastern Alaska thermal springs- - - - - - - - - 6 3 Acknowledgments- - - - - - - - - - - - - - - - - - - - - - - - - - - - 6 5 References - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 66 1' IGIJ RES Figure 1. Locat ion of reported thermal springs, southern Southeas tern Alaska- - - .- - - - - - - - - - -. - - - - - - - - - - - - Solubili ty of quartz as a function of temperature- - - - - - Silica mixing model examples - - - - - - - - - - - - - - - - Geologic map of tik kine River area - - - - - - - - - - - - - Geologic map of Fowler Hot Springs area- - - - - - - - - - - Location map, Bradfield hot springs- - - - - - - - - - - - - Gcologic map of Bell Island and Bailey Bay Hot Springs area- Bailey Bay Hot Springs - - - .- - - - - - - - - - - - - - - - 1,ocation map, Baker Island Hot Springs - - - - - - - - - - - iii TABLES --Page Table 1. Methods and expected precision: DGGS water chemistry - . -. - .- - - - -. - - - - - - - - - - - - - - - Cl~emical composition and physical proper ties of Chief Shakes hot springs- - - - - - - - - - - -. - - - - - - - - Chief Shakes hot 8pring.i geother~nometry- -. - - - - - .- - - - Chemical composition and physical properties of Barnes Lake warm springs- - - - - - - - - - - - - - - - - - - - - - - Barnes Lake warm 8pring~#c.othermometry-- - - - - - - - - - - Chemical compoeition and physical propcrtics of Fowler Hot- Springs - - - . - - - - - - - - - - - - - - - - - - - - Fowler Hot Springs geothermometry- - - - - - - -- - - - - - - Chemical composition and pkzysi.cal properties of Twin Lakes warm springs- --- - - - - - - - - - - - - - - - - - - - Twin 1,akes warm springs geothermometry - - - - - - - - - - - Chemical compoai tion and physical properties of Brad field hot springs---- - .------------------ Bradfield hot springs geothermometry - - - - -- - - - - - -- - Bell Island Hot Springs temperatures, 10/5/79- - - - - - - - Chemical cornpov it ion arid physical properties of Be1 l Is land Hot Springs - - - - - - - - .* - - - - - - - - - - - - - - Bell Island Hot Springs geothermometry - - - - - - - - - - - Temperatures and flow rates, Bailey Bay Hot Springs- - - - - Bailey Bay llot: Sprir~g~,upring-3 water jet height and temperature- - .- - - - ... - -. - - - - - - - - - - - - .. - Chemical composition and physical properties of Bailey Bay Hot Springs - - - - - - - - .... - - - - - - - - - - - - - - Railey Bay Hot Springs geothetmometry- - - - -- - - - - - - - Summnry, southern Southeas tern Ala~ikan thermal springs sites - - - - - - - - - - - -. - .- - - - - - - - - - - - APPENDIXES Appendix A - Abbrev~ationa, unit symbols, and conversion factors - - - 70 Appendix B - Precision of water analyses - - - - - - - - - - - - - - - 7 1 Appendix C - ICAP determinations of minor and trace elements -- - - - - 72 ABSTRACT information has been gathered on 13 reported tl~erm,+l--springsites, 12 in southern S0utheast:ern Alaska and one in western British Columbia. Five of Ihc reported sites could not be substarltiated hy DGGS. The eight know1 t:herrrinl spring sites are associated with granitic terrain and, except for Baker Tslaud Hot Springs, occur within or near intensively Erae tured Cretaceolrs-ape plutons of th~Coast Range Bac?~olith . Thermal -spring surface temperatures range from 21"~ win Lakes) Lu 91.5"C (Bailey ~ay). The greatest discharge occurs at Chief Shakes hot springs (450 I pm). Bell Island Hot Spririgs, which has about a 100--1pm dis- charge and a 70°C temperature, ha6 had the most development. Two previo lsly unreported thermal-spring sites, Barnes Lake warm springs and Bradf ield hot springs, have a low rate of discharge and respective surface temperatures of about 25" and 54°C. The known tliernlal springs probably originate from circulation of izetporic waters through deep-seated fracture and tault systems. The chemical con- st i rrl~n~sof the alkal i-sulEate to alkal i-chloride thermal waters are probnb ly derived from interaction of the deeply circcll~tingmeteoric waters with tll~ granitic wall rocks. Chemica t gr-othermometry suggests nubsl~rface temperatcrrps of '>So to 151°C. Tf waters are beix~gheated ~olelyby col~clnction from wall rocks, circulatinrr d~pthsinust bp about 1.5 to 5 km, as~rlmin~geotiiermal gradients of 30" to 50°C/km. Variations in temperature, discharge, and chemistry were noted at several ermal springs for wliich previous records are available. A major decrease. in 1 ica nnd potassium concentrations at Chief Shakes hot springs is suggested by comparing recent analyses of water chemistry to Warjng's (1917) arigin,~l analysis. The rate of discharge at: Bell Island Hot Springs may have increac,ed by a Eactor of two since Waring's visit to the springs. Subsurface reservoirs associated with thermal springs in southern Soutli- caasttArn A1a1~;lcaRTC of low t:vnper~turt-? and are probably iimitetl in exceiit, corn- pared to geothermal fields now being used elsewhere in the world. Only the Beel Island and Bailey Bay sites now off~rany potential for generation of electric; ty; rhese sites could a190 be used for a variety of direct uses such as space heating, wood or luntber processing, and perhaps auuaculture. The other sirt.s have less potential but could be used locally for space heating or ;igricnlturc enhanremerit. INTRODUCTION The Alaska Division of Geological and Geophysical Surveys (IIGGS) in PO- operation with the U.S. Bep.~rtmentof Energy, in 1979 embarked or1 a 3-y~13r program of assessinp the ~eoth~rmalenergy resource potent jal of thermal- spring sircis in Alaska. Evaluation ,)f these sites is based on geological clr~d geochemicjii (jato, gsntllc?rmometric modcl s, anti geophysical data where avai l- able. More than 100 hot-.spring qi ti,<; have been reported to exist in Alaska. 1"re sites are d isperscd t1i~-oughouL the state but Y ignificar~tconcentrat ions and be119 of rlrclrnlal sprin~ec1i.c ur along r:lle AJeutian Range, in Southessterr~ Alil~kii,and across crnL~.iilA1clsh.a. Th,? firsC comprehensive inven~oryof the t1,enrral springs of Alas1c.l \.;:Is, pub1 islit ii in 1'11 7 h y Waring. Since then brief silnnnar ies of A1;nak.m ther mizi spr ~IIL:~nave appeared in Waring ( lP651, Mill cr (1973): White and Willinrll:, (199')), end Muffler (1979). The inn~rrecent rom- pr c.llcxrlsivc surlvricary 01 hl lzskat itlcr~nllspring ~~IVCHIigttt. ~OIIHWL~S romp i l f'tl ' *,r K<~rklc(1979). 'Ilhe scope af the i.nitl.ii! ,at:se.ss~neiltof geothermaI resources ar; undertalcerl by I)i:G% i.nc1udr.s 1) invcsi:i~;ating all thermal--spri.ng sites previously reported but not as yet visited or- s~u:li:~dby n scie~~~.;fi.cteam; 2) providing up-to-- date data ancl more d6ita.i l.eci ..ii:urli.es of previously ia~vestigai::edsites ; anc! 3) 'I,ocat i.ng and iitvcs t igat i,trg; add it i.onal thrrrnil-spr.~i.ng sites not previously rr2ported. The assessment work includes recorlrraissance of site geol.ogy and hydrology, ir~trestigation iiil t:tlt:r~nal.--spring charac teristic s in,clwing tempera- tures and flow rates, :!ud ~e~ic:l-ic~~iiicalsatiipl.ing and t-lnalysis of the rocks and thermal waters at: the sit<.. 'l'hi:; inlormati.on .Is used to describe the site, to estimate reservoir. temper~itui-e, to evaluate tilt: extent of mixing of thermal waters witit colder witter!g, .,and to detern1i.n~the geotl-lermal energy potential. of the si tt!. Thcse da tn for ,:'I,l 1.h~tlrerrnni~l sy.)ri.ng nites of Alaskcl will be cola-. p.ilc?d j.nto u geotl.~esmaliitl.an, 'TI-ltt inf:)rnluti.on i.3 also being used i:o se'tect: s i t-es with the highest. pt:i:t:n t i-zl