Catalogue of active geothermal manifestations in West Iceland

Transcription

1 Report Project no.: Catalogue of active geothermal manifestations in West Iceland (1): Kleppjárnsreykir, Kársnes, Deildartunga, Hurðarbak South in Borgarfjörður Maryam Khodayar Héðinn Björnsson Prepared for the Energy Resources Division of Orkustofnun ÍSOR-2005/011 March 2005 ICELAND GEOSURVEY Reykjavík: Orkugarður, Grensásvegi 9, 108 Rvk. Tel.: Fax: Akureyri: Rangárvöllum, P.O. Box 30, 602 Ak. Tel: Fax:

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3 Key page Report no. Date Distribution ÍSOR-2005/011 March 2005 Open Closed Report name / Main and subheadings Catalogue of active geothermal manifestations in West Iceland (1): Kleppjárnsreykir, Kársnes, Deildartunga, Hurðarbak South in Borgarfjörður Authors Maryam Khodayar and Héðinn Björnsson Number of copies 15 Number of pages 71 Project manager Maryam Khodayar Classification of report Project no. Tectonic geothermal mapping Prepared for The Energy Resources Division of Orkustofnun Co-operators Abstract The results of a campaign of GPS-mapping of geothermal manifestations in the Borgarfjörður of West Iceland are reported. The work is a part of the project Bergsprungur í skjálftabeltum og gosbeltum. Five areas were selected for the mapping. Four are in Reykholtsdalur and is near the shores of Hvítá river. All areas are a short way south of the epicentre of the 1974 Borgarfjörður earthquakes. The field investigations consisted of mapping of the hottest geothermal areas with a GPS device. These areas were identified on the basis of temperature profiles as well as other typical features associated with geothermal manifestations. Qualitative observations were also made simultaneously on each mapped point. The geothermal manifestations mapped are complementary information on the status of tectonics in West Iceland, with respect to the evolution of the plate boundaries and intra-plate deformation. The results show reactivation of the underlying tectonic structures leading to geothermal activity at the surface, as well as a strong relation with the 1974 intra-plate earthquakes in Borgarfjörður. The present catalogue of the raw field data is prepared at the request of the Energy Resource Division of Orkustofnun in order to be incorporated into the databank of Orkustofnun. Fracture analysis in relation to geothermal was also carried out during this campaign, but data will be presented separately. Key words Geothermal manifestations, Reykholtsdalur, GPS-mapping, temperature profiles, tectonics, databank, catalogue ISBN-number Project manager s signature Reviewed by HF - 2 -

4 TABLE OF CONTENTS INTRODUCTION... 5 CHAPTER 1 KLEPPJÁRNSREYKIR SKRÚÐUR... 9 CHAPTER 2 KÁRSNES SOUTH CHAPTER 3 KÁRSNES NORTH CHAPTER 4 DEILDARTUNGA CHAPTER 5 HURÐARBAK SOUTH REFERENCES

5 INTRODUCTION In the autumn of 2004, we carried out a campaign of GPS-mapping of geothermal manifestations in the Borgarfjörður Block in West Iceland. This block is caught between the active Reykjanes-Langjökull Rift Zone to the east and the extinct Tertiary Snæfellsnes Rift Zone to west (Fig. 1). A Quaternary intra-plate volcanic chain, the Snæfellsnes Volcanic Zone, stretches perpendicular to these rift zones. The 1974 Borgarfjörður intra-plate earthquakes, up to magnitude 6 (Einarsson et al., 1977), occurred at the eastern tip of this volcanic zone (Fig. 1). Five areas covering a northerly zone were selected for the GPS-mapping of geothermal manifestations (Khodayar et al., 2004; Björnsson, 2005). From south to north these are Kleppjárnsreykir, Kársnes South, Kársnes North, Deildartunga, and Hurðarbak South (Fig. 2). The first four areas are in Reykholtsdalur, and the last one is near the southern shore of Hvítá River. These manifestations are located near to the epicentre of the 1974 Borgarfjörður earthquakes. The field investigations involved mapping of the hottest geothermal areas with a GPS device. We identified these areas on the basis of temperature measurements as well as typical features associated with geothermal manifestations. Qualitative observations were made on each mapped point. Water chemistry and discharges, were not studied during our investigations, however. Our field investigations are a part of the project Bergsprungur í skálftabeltum og gosbeltum. This project focuses on the geology and tectonics of West and South Iceland with respect to the evolution of the rifts and the transform zone(s). The geothermal manifestations mapped are complementary information that leads to better understanding of the latest status of tectonics in West Iceland. Results of this mapping show a probable reactivation of the underlying tectonics leading to geothermal activity at the surface. At the request of the Energy Resources Division of Orkustofnun, we prepared the present catalogue containing the raw field data collected during our campaign of GPSmapping. This is in order to incorporate the data in a databank. Each of the five mapped areas is presented in one separate chapter within the catalogue. The maps, points (P), temperatures, features, general comments, coordinates, and photographs (when available) are given for each mapped feature. The directions of the structures on the map are given by the GPS-device with respect to the North. Fracture analysis in relation to the geothermal manifestations was also carried out during this campaign, but data are presented separately, in a work in preparation. That - 5 -

6 work will also deal with a more thorough interpretation of the results of the GPS-mapping with respect to the seismicity and the evolution of the plate boundaries and intraplate tectonics in West Iceland. Notes: The size of the geothermal manifestations on the maps is slightly exaggerated for clarity. The coordinates presented in the catalogue are those obtained by the GPS device Trimble, used for the mapping. These coordinates may present distortion if projected onto topographical maps. Due to the resolution of the GPS-technology, the location of the smaller features below 2 m size may present an inaccuracy of 1 2 m. For single point, the coordinates presented are of those of the point, but for areas, the coordinates correspond to the beginning of the structure

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12 Locality Point (P) Number Max. temperature inside of the structure (in C ) Other temperature inside of the structure (in C ) Temperature in geothermal zone outside of the structure (in C ) White deposition (silica?) Algae Oxidation and possible silica deposition Bubbles Tectonic alignment of the manifestations Kleppjárnsreykir-Skrúður (N of Björk) Comment GPS coordinates Picture 1 a , 97.1 X X b c 10 cm to the N: 66.5, 60 X X X X d X e 98 f 96.2 X g 99.4 Concrete structure with steam escaping from a pipe in it In the geothermal stream flowing from P1 (a) Another concrete structure on top of manifestation(s) Heavily boiling spring inaccessible for temperature measurement Concrete structure around springs A small boiling spring beneath a concrete construction Boiling spring beneath a concrete structure 64 39'14,77402'' N 21 24'09,25999'' W 64 39'14,85089'' N 21 24'09,38493'' W 64 39'15,02722'' N 21 24'08,92878'' W 64 39'15,04776'' N 21 24'08,95732'' W 64 39'15,44412'' N 21 24'09,02658'' W 64 39'15,26606'' N 21 24'09,06757'' W 64 39'15,43115'' N 21 24'09,30873'' W Figs. 4a and 4b Figs. 4a and 4b Fig. 4a Fig. 4a Fig. 4a Fig. 4a Fig. 4a

13 To the S, on a N-S line: 74, 80, 64.1, 62.5, 63.9 At 1.5 m, 3 m, and 5 m to the N: 54.1, 48.1, 32.6 ; at 5 cm to the W: 50 ; at 5 cm to the E: 54 X X N32 Hottest points on a N32 line in a sub-channel 64 39'21,18261'' N 21 24'16,76945'' W Kleppjárnsreykir-Skrúður (N of Björk) , , 85.2, 84.4 To the N, on a N-S line: 57.5, , 57.4, , 64.8, X X X X X X X N14 3 eyes, the biggest with 15 cm diameter and 10 cm depth. Form a tectonic line N03 with P eyes with irregular shape. Form a tectonic line N03 with P.3 and P eyes, each 4 cm diameter, forming a N14 line. Form a net tectonic line N03 with P.3-4 and P.6-8 Form a tectonic line N03 with P.3-5 and P '21,439003'' N 21 24'16,49338'' W 64 39'21,42896'' N 21 24'16,52155'' W 64 39'21,51973'' N 21 24'16,49937'' W 64 39'21,30245'' N 21 24'16,42072'' W X Form a tectonic line N03 with P.3-6 and P '21,60905'' N 21 24'16,33911'' W X Form a net WNW tectonic line with P.9 and P.22, and N03 with P '21,75834'' N 21 24'16,40057'' W Fig , 44.9 X Form a net WNW tectonic line with P.8 and P '21,83257'' N 21 24'16,71066'' W Fig

14 m to the N: 52.7 X Small eye with irregular shape in sediments. Could form a tectonic line N165 with P.11-13, 17, and '21,52611'' N 21 24'16,87842'' W Fig X Could form a tectonic line N165 with P.10, 12-13, 17, and '21,46434'' N 21 24'16,96730'' W Fig. 5 Kleppsjárnsreykir-Skrúður (N of Björk) X X X At 30 cm: 53,3. 30 cm to N: 50,6 X Eye in sediments. Could form a tectonic line N165 with P.10-11, 13, 17, and Eye. Could form a tectonic line N165 with P.10-12, 17, and eyes with 10 cm diameter. Only the hottest is mapped. Form a tectonic line N10 with P , 45.2 X N65 Manifestations on a N65 line , 65.1, 45.4, 37.1, 42 X N20 Manifestations on a N20 line 64 39'21,49080'' N 21 24'16,96732'' W 64 39'21,46516'' N 21 24'16,92195'' W 64 39'21,52534'' N 21 24'17,41354'' W 64 39'21,39994'' N 21 24'17,11364'' W 64 39'21,48027'' N 21 24'17,20487'' W Fig X Could form a tectonic line N165 with P.2, P.10-13, and '21,59890'' N 21 24'17,09039'' W Fig , 61.2 X 3 eyes; only the hottest is mapped. Could form a tectonic line N10 with P.14, and '21,66389'' N 21 24'17,34412'' W Fig X X Could form a tectonic line N10 with P.14, P.18, and P '21,60397'' N 21 24'17,34922'' W Fig

15 , , 58.2, 62.2, 59.8, 61.7, 50.2, 60.8, 53.9, 57.2, 52.3, 39, 45.9 X N10 Manifestations on a N10 line. Could form a general tectonic line N10 with P.14, P and P '21,63103'' N 21 24'17,31957'' W Fig. 7 Kleppjárnsreykir-Skrúður (N of Björk) On a N-S line to the S: 52.5, 35.4, 43.8 To the W: 48.7 ; at 0.40 m, 1.4 m and 2 m to the N: 45, 44, 35.5 X X X On a NE- SW line, including P.24: 78.2, 60.4, 66.4, 70, 57.8, 64.1, 58.3, 61.2 at 5 m, 10 m, 15 m, 20 m, and 25 m to SW: 53.9, 44.6, 40.4, 40.7, 39.1 X X Eye with 30 cm diameter and 40 cm depth. Could form a tectonic line N165 with P.10-13, 17, and 22, and a tectonic line N10 with P.14, P and P.22 Eye with 10 cm diameter and 10 cm depth. Form a net WNW tectonic line with P.8-9. Could form a tectonic line N165 with P.10-13, 17, and 21, and a tectonic line N10 with P.14, P Big boiling pool with bursting water. Concrete construction around it. Could form tectonic line N45 with P.24 On a N45 line, in the small geothermal stream running from P.23. Form tectonic line N45 with P.23 Outline of the area containing P '21,73736'' N 21 24'17,14841'' W 64 39'21,94073'' N 21 24'17,15463'' W 64 39'21,06263'' N 21 24'17,63268'' W 64 39'21,05669'' N 21 24'17,67489'' W 64 39'20,78933'' N 21 24'18,44180'' W Fig. 7 Fig

16 Kleppjárnsreykir-Skrúður (N of Björk) , , 62.3 Surrounding P. 26: 44.6, 44.9, 51.1 ; S of it, on a N-S line: 36.8, 37.4, 37.4, 38.3, 44.9, 40.9, 37.9, 37.8 At 10 cm: 42.1, 44.5 At 10 and 20 cm to N: 52 and 50 ; To W: 47.9 ; at 10 and 20 cm to the S: 54.5 and cm to N: 55.1 East of the ditch. Form a N-S tectonic line with P East of the ditch. Form a N-S tectonic line with P.26, and P East of the ditch. Form a N-S tectonic line with P.26-27, and P East of the ditch. Form a N-S tectonic line with P and P '25,45921'' N 21 24'18,71654'' W 64 39'25,51695'' N 21 24'18,77161'' W 64 39'25,53211'' N 21 24'18,76142'' W 64 39'25,55637'' N 21 24'18,77645'' W Surrounding: 47.1, 48.2, 42.8 ; at 1 and 2 m to the N: 38.9 and 38.3 East of the ditch. Form a N-S tectonic line with P These points are all south of the pipe that is transversal to the ditch 64 39'25,60907'' N 21 24'18,75208'' W

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19 Chapter 2 KÁRSNES SOUTH

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22 Locality Point (P) Number Max. Temperature inside the structure (in C ) Other Temperature inside the structure (in C ) Temperature in geothermal zone outside the structure (in C ) White deposition (Silica?) Algae Oxidation and possible silica deposition Bubbles Tectonic alignment of the manifestations Comment GPS Coordinates Picture At 20 and 25 cm to the N: 91.1 and 78.9 ; at 30 cm to the NE: 87.7, 25 cm to the E: 71.1, 25 cm to the SE: 92.6, 50 cm to the S: 91.3 X X X X Big eye, with 50 cm diameter, 30 cm depth, in a pool from where runs a geothermal stream 64 39'32,73027'' N 21 24'18,68691'' W Figs. 9a and 9b Kársnes South 32 At 1.5 m S of P. 32, down stream on an E-W line: 87.3, 81.5, 82, 75.7, 73.8, 72.1, 68.6 ; then on a N-S line: 62.9, 61.4, 59 X X X X The pool with 0.60 m diameter containing P '32,67731'' N 21 24'18,60505'' W Figs. 9a and 9b

23 a '28,86991'' N 21 24'14,24513'' W b 14.1 To the W: '28,83836'' N 21 24'14,28881'' W Kársnes South 33 c 11.4 d 14.2 To the E: 4.6 Ground temperature at the time of measurement is < 4 C. Ice exists everywhere in the river, except in the northern shore of Reykjadalsá where P.33 a-k are located. These points are to the northeast of the greenhouse of Skrúður 64 39'28,87332'' N 21 24'14,63915'' W 64 39'28,86629'' N 21 24'14,65801'' W e '28,87215'' N 21 24'14,82168'' W f 11.7 To the W: '28,92062'' N 21 24'14,94823'' W g '28,83448'' N 21 24'15,34509'' W

24 h '28,86576'' N 21 24'15,51878'' W 33 i 14.8 j 11.9 Ground temperature at the time of measurement is < 4 C. Ice exists everywhere in the river, except in the northern shore of Reykjadalsá where P.33 a-k are located. These points are to the northeast of the greenhouse of Skrúður 64 39'28,84806'' N 21 24'15,60113'' W 64 39'28,84290'' N 21 24'15,67361'' W Kársnes South k '28,87440'' N 21 24'15,93474'' W , 63.4 To the W: 42, 34.3 X 22 Isolated water pond 64 39'33,73402'' N 21 24'25,53724'' W cm to the S: 42.4 ; 20 cm to N: 38.6 X Shallow small water pool in sediments 64 39'33,49159'' N 21 24'25,57472'' W cm to the S: cm to the S: 38.6 ; 20 cm to the N: 40.6 X 64 39'33,57143'' N 21 24'25,69894'' W

25 To the N, on a N-S line: 76.9, 62, 59.7, 62.2, 58 In the geothermal stream: 51.1, 46.7, 49, 34 X X X N140 Beautiful perfect big eye, with 1 m diameter, 0.5 m depth in sediment. Form a N140 line with P.35 and P.36. Very little deposition (silica?). Bubbles in the central part 64 39'33,57600'' N 21 24'25,85482' W Fig At 0.5 m to the W, to the S, to the N, and to the E: 40.9, 40.3, 33.4, 40 X X N110 Big beautiful eye 1 m diameter, 20 cm depth, in swampy sediments, with bubbles in the central part, aligned N110. Worms and small fishes swimming near the eye. Very special light green colour 64 39'32,00527'' N 21 24'25,37256' W Fig. 11 Kársnes South Very big eye, with 1 m diameter and at least 2 m depth, in the geothermal stream and swampy sediments 64 39'32,89192'' N 21 24'25,79721'' W Group of small eyes with 2-3 cm diameter, in the sediments inside the stream. Could form a N155 line with P '33,07920'' N 21 24'25,95040' W 41 Outline of the area containing P and P These points are north of Reykjadaslá and the water from this river mixes with geothermal water through a channel 64 39'32,92610'' N 21 24'26,85308' W

26 , 58.5 X Group of small eyes with 3-4 cm diameter in swampy sediments in the geothermal stream. Altered gastropod shells and dead small fishes lie by the eyes 64 39'33,04514'' N 21 24'25,53748'' W Between P. 42 and 43: 48, 40.5, 45.5 Group of small eyes in swampy sediments in the stream. Forms a N150 line with P '33,08262'' N 21 24'25,61689' W Kársnes South Between P. 43 and 44: 35, 34.1, 33.5 Between P. 44 and 45: 33.3, 36.2, 35.7 X X Group of small eyes in sediments of the stream A small eye with 3 cm diameter. Form a N125 line with P '33,25551'' N 21 24'25,89777' W 64 39'33,32138'' N 21 24'25,99480'' W , 57.8, 50.2 Surrounding: 13.2, 9.1, 5.7 At the northern flank of Reykjadalsá river, against yellow grass field. Special green vegetation associated with manifestation 64 39'30,30743'' N 21 24'23,89105' W Between P. 46 and 47: 9.9, 7.1, 7.6 At the northern flank of Reykjadalsá river, against yellow grass field. Special green vegetation associated with manifestation 64 39'30,30391'' N 21 24'24,30204' W

27 Kársnes South On two N-S lines to the S. The western line: 11.7, 18.5, 15.2, 16.2, 15, 17, 15.1, 10. The eastern line: 12, 13, 12.2, 13, 11.3, 10.1, 10, 10.5 To the N: ; to the W: P.48 is in a zone, found by temperature measurements along two parallel N-S lines. The zone is in the grass field, without surface manifestation. Soil temperature was ~ 5 C at the time of mapping 64 39'34,63286'' N 21 24'19,49427' W

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34 Locality Point (P) Number Max. temperature inside of the structure (in C ) Other temperature inside of the structure (in C ) Temperature in geothermal zone outside of the structure (in C ) White deposition (Silica?) Algae Oxidation and possible silica deposition Bubbles Tectonic alignment of the manifestations Comment GPS coordinates Picture At 0.5 m to the S: 42.5, 45.1, 38.8, 47.4 ; at 3 m to the N: 20.8, 20.5, 21.9, 32.2, 38 1 m to the NE: 40.8 ; at 1 m to the S: 29.3 ; at 1 m to the NW: 21.2 ; 1 m to the W: 35.5 X X Eye with 20 cm diameter, in a small pond full of swampy sediments. Many dead worms present Eye with 30 cm diameter, 20 cm depth, in swampy sediments. Could form a N25 line with P '44,08541'' N 21 24'29,08017' W 64 39'44,28668'' N 21 24'28,83899' W Kársnes North X Eye with 20 cm diameter in swampy sediments on the edge of grassy area in the pond. Very little algae 64 39'44,44031'' N 21 24'28,93175'' W

35 X Eye in swampy sediments in a 1.5-m diameter pond. Jellytype alteration (algae and sediments) 64 39'44,53574'' N 21 24'28,87629' W X Eye in swampy sediments in a 1.5-m diameter pond. Jellytype alteration (algae and sediments) 64 39'44,55899'' N 21 24'28,90101' W Kársnes North X X X X Eye in swampy sediments in a 1.5-m diameter pond. Jellytype alteration (algae and sediments) Outline of the area containing P Eye with small discharge in swampy sediments 64 39'44,56883'' N 21 24'28,92610'' W 64 39'44,56367'' N 21 24'28,79992'' W 64 39'44,65271'' N 21 24'28,39198' W Fig X Eye in the N140 man-made channel 64 39'44,58569'' N 21 24'28,38256'' W Fig Small eye in swampy sediments on the grassy edge of the N140 man-made channel 64 39'44,58069'' N 21 24'28,48050' W Fig cm to the W: 53.6 ; 50 cm to the N: 52 Small eye on the edge of a small pond. Form a N10 line with P '44,72658'' N 21 24'28,75683' W Fig

36 At 50 cm to the S, SW, W, N, and E of P. 59: 41.6 ; 42.4 ; 44.8, 48, 53.6 In the middle of the same pond as P.59. Could form a line N14 with P '44,77377'' N 21 24'28,74320'' W Fig. 14 Kársnes North To the S, on a N-S line: 53.3, 54.9, , 54.9, 50.3, 61.4, 63.2, 48, 69.8, 53.6, 52, 65.7, 70.7 On a WNW line E of P. 61, every 5 m: 46.4, 34.7, 27.6, 24.9, 26.8, 22.2, 22.4, 24.3, 21.9 From P.62, every 5 m to the SE: 46.4, 34.7, 27.6, 24.9, 26.8, 22.2, 22.4, 24.3, N of P. 62: 46.9, 42.4, 44.8, 41.6 X N142 In the middle of the channel. Form a line N80 with P.57 and 58 Outline of the area containing P '44,58369'' N 21 24'28,39627' W 64 39'44,54494'' N 21 24'28,30126' W Fig X X Eye with 10 cm diameter, 0.5 m depth, in swampy sediments In swampy sediments. Could form a N120 line with P.65 and a N15 line with P '45,11487'' N 21 24'28,31468'' W 64 39'45,30694'' N 21 24'28,08379'' W

37 In swampy sediments. Could form a N120 line with P '45,21527'' N 21 24'28,34452'' W Kársnes North , 44, 36.5, , 44.6, 42.3, 32.9 X X Pond with 1 m diameter, 20 cm depth, containing P.63 Pond with 1 m diameter, 15 cm depth, containing P '45,14864'' N 21 24'28,30392'' W 64 39'45,20087'' N 21 24'28,36537'' W 68 Outline of the area containing P '45,28870'' N 21 24'28,23724'' W

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42 Locality Point (P) Number Max. temperature inside of the structure (in C ) Other temperature inside of the structure (in C ) Temperature in geothermal zone outside of the structure (in C ) White deposition (Silica?) Algae Oxidation and possible silica deposition Bubbles Tectonic alignment of the manifestations Comment GPS coordinates Picture To the E, on an E-W line: 86, 82.6, 67.5, 68, 70.3, 65, cm to E: 33.6 ; 10 cm to the S: 30.4 ; 10 cm to the N: 29.6 X N90 Elongated shallow hot structure, with anoxic mud, containing P '45,50670'' N 21 24'40,84451'' W Fig. 16 Deildartunga X X Hottest point in P On an E-W line, (a) to the W: 84.1, 86.3, (b) to the E: 84.5, 83.1, 76.6 To the S: 29.6 ; To the E: 52 ; To the N: 40.2 ; To the W: 20 X X N88 Elongated shallow hot structure, with anoxic mud, containing P '45,50015'' N 21 24'40,74926'' W 64 39'45,53953'' N 21 24'40,79939'' W Fig. 16 Fig X Hottest point in P '45,55981'' N 21 24'40,67182'' W Fig

43 On an E-W line, (a) to the W: 76.8 (b) to the E: 78.3, 62.3, 73.1, 61.1 To the E: 56.1 N90 Elongated hot structure containing P.74. Partly accessible due to swampy anoxic mud 64 39'45,58894'' N 21 24'40,82790'' W Fig X X Hottest point in P '45,65733'' N 21 24'40,80058'' W Fig On an E-W line, to the W: 82.4, 81 X X N90 3 eyes in the artificial stream 64 39'45,80456'' N 21 24'40,88710'' W Fig On a N-S line to the N: 76.1, 66.7 X X N08 3 small bubbling eyes, with 1 cm diameter, in the artificial stream 64 39'45,80250'' N 21 24'40,92767'' W Fig. 16 Deildartunga On a N-S line to the N: 81.4, 80.2, 67 X N , 66.3 X N On a N-S line: 85.5, 81.4, 80.2, 67 On an E-W line from P 80, (a) to W: 82, 80.5, 75.1, 67; (b) to the E: 65 At 0.5 m, 1 m, and 1.5 m E of P 80: 60.4, 62.5, 25.6 ; at 20 cm S of P. 80: 55.4 ; at 20 cm S of P 80: 35.5 X N05 X X N105 Line of bubbles in the artificial stream. Is the same as P.79 A line of bubbles in the artificial stream, striking N50. Due to inaccessible conditions, the point was mapped manually from 1 m distance Line of bubbles in the artificial stream. Is the same as P.77, mapped from the north Area in slightly muddy artificial stream, containing P.81. The point lies near the edge of a man-made gravel hill, just N of the pipes coming from the pump house. Silica abundantly associated with the manifestation 64 39'45,92642'' N 21 24'40,79268'' W 64 39'45,82989'' N 21 24'40,62743'' W 64 39'45,92642'' N 21 24'40,79268'' W 64 39'46,28247'' N 21 24'40,27442'' W Fig. 16 Fig. 16 Fig

44 Hottest point in P '46,25035'' N 21 24'40,09136'' W cm to the N: 94.1 X X 1 eye with 20 cm diameter and two zones of bubbles. Located on top of the man-made gravel hill. Bubbles come out of the gravels. Abundant silica associated with the manifestation 64 39'46,36486'' N 21 24'40,17890'' W Fig. 17 Deildartunga ; 94.9 X X X , 95.3 N180 Eye with 30 cm diameter, 1 cm depth, on the man-made gravel hill. Form a line N176 with P.81 and 82. Silica associated with the manifestation 3 small boiling bubbling zones in the artificial stream mapped as one structure due to their sizes '46,45716'' N 21 24'40,17233'' W 64 39'46,63853'' N 21 24'39,89709'' W Fig. 17 Fig On a N-S line, (a) to the S: 97.1, 96.5 ; (b) to the N: 97,1; 96,5. X X N10 5 eyes, 4 of which are in swampy sediments of the artificial stream, and 1 is in thick silica deposition in the man-made gravel hill. Eyes are bubbling, and form a net N 10 fracture 64 39'46,61072'' N 21 24'39,84304'' W Fig Small eye with 10 cm diameter, 30 cm depth, in clay sediments, on the N10 fracture 64 39'46,71251'' N 21 24'39,80576'' W Fig

45 X N10 2 eyes, one elongated (0.40x0.10 m), and the other round (5 cm), on the N10 fracture. Are mapped as one structure due to their size 64 39'46,71070'' N 21 24'39,79554'' W Fig To the N: 94.3 ; To the E: 87.3 X X X N05 Eye with 50 cm diameter, 20 cm depth, and some discharge. Three hot points are present; the two hottest are on a N10 line where intense bubbling 64 39'46,84034' N 21 24'39,81061'' W Fig X X X N40 Eye with 60 cm diameter, 20 cm depth, on a N40 line '46,90046' N 21 24'39,60987'' W Fig. 19 Deildartunga X Vertical pipe on top of natural spring. Intense steam escape from it. Bubbles can be seen down from the open mouth of the pipe 64 39'47,26757'' N 21 24'38,96332'' W Fig X X Vertical pipe on top of natural spring. Form a N12 line with P '47,59778' N 21 24'38,77585'' W Fig X Big pool with 0.5 m diameter, 30 cm depth, against the concrete rim. Form with P a net N135 tectonic line 64 39'48,34948' N 21 24'37,98605'' W Fig. 21a X Pool with 10 cm diameter, bubbling. Form with P.92 and P a net N135 tectonic line 64 39'48,37361'' N 21 24'38,07060'' W Fig. 21a

46 X Pool with 20 cm diameter, boiling. Form with P and P a net N135 tectonic line 64 39'48,40711'' N 21 24'38,10886'' W Fig. 21a X Pool mapped manually from 1 m distance because of inaccessible conditions due to bursting boiling water 64 39'48,43948'' N 21 24'38,20536'' W Fig. 21a X Severely boiling pool in the stream, with 30 cm diameter and bursting water from beneath the surface of the stream 64 39'48,47410'' N 21 24'38,05396'' W Fig. 21a Deildartunga X Pool in the hill, with 0.5 m diameter and bursting water to 0.5 m height. Was mapped manually at 1 m distance due to inaccessible conditions 64 39'48,46710'' N 21 24'38,25005'' W Fig. 21a 98 95,4 2 eyes with 5 cm diameter, on the edge of the hill. Mapped manually at 1 m distance because of inaccessible conditions due to bursting boiling water. Form a net N90 tectonic line with P '48,53136'' N 21 24'38,42117'' W Fig. 21a X Pool with 20 cm diameter and bursting water in the stream. Form a net N90 line with P.98 and P '48,53337'' N 21 24'38,21563'' W Fig. 21a

47 X Pool with 15 cm diameter by the edge of the hill. Form a net N90 tectonic line with P.98 and P.99. Was mapped manually at 1 m distance because of inaccessible conditions due to bursting boiling water 64 39'48,52991'' N 21 24'38,40748'' W Fig. 21a X Pool with 1 m diameter and severely bursting water 64 39'48,59187'' N 21 24'38,28934'' W Fig. 21a Deildartunga X X N55 Pool in the hillside with bursting water to 0.5 m height Pool with 30 cm diameter and seriously bursting water at 0.5 m height, completely in the slope of the hill. Form a net tectonic line N55 with P '48,71597'' N 21 24'38,35540'' W 64 39'48,76359'' N 21 24'38,49646'' W Figs. 21a and 21b Fig. 21a N55 Elongated pool in the slope. Form a net tectonic line N55 with P.103, and '48,78105'' N 21 24'38,41859'' W Fig. 21a X N55 Eye with 0.50 m x 0.10 m. Manually mapped at 1 m distance due to bursting boiling water and intense steam. Form a net N55 tectonic line with P and P '48,79075'' N 21 24'38,34461'' W Fig. 21a

48 X N55 Eye with 10 cm diameter, mapped manually at 1 m distance due to bursting boiling water and intense steam. Form a net N55 tectonic line with P and P '48,81909'' N 21 24'38,29112'' W Fig. 21a X N55 Eye with 1 m diameter and bursting boiling water at 10 cm height. Form a net N55 tectonic line with P Could form a N115 tectonic line with P '48,83845'' N 21 24'38,22143'' W Fig. 21a Deildartunga X N N05 Eye with 0.5 m diameter and boiling bursting water in the stream. Could form a N115 tectonic line with P.107 Big eye with 1 m diameter in the stream. Is on the fracture N07 of P '48,82886'' N 21 24'38,14023'' W 64 39'48,91817'' N 21 24'38,11015'' W Fig. 21a Fig. 21a N05 Eye with 0.5 m diameter on the edge of the concrete protection wall. Is on the fracture N07 of P '48,97871'' N 21 24'38,13683'' W Fig. 21a X N07 Fracture N07 with 1 m long and 2-10 cm wide in the stream. Boiling water burst out of the fracture 64 39'49,12129'' N 21 24'38,11073'' W Fig. 21a X N07 Hole with 1 m diameter and bursting boiling water in the slope of the hill. Is on northerly fracture P.111 or P '49,11957'' N 21 24'38,14853'' W Figs. 21a and 21c

49 X N05 Eye with 0.5 m diameter and boiling bursting water in the stream. Form a N05 tectonic line with P and is on N05 fractures P '49,30222'' N 21 24'38,12487'' W Fig. 21a X N05 Eye in the stream with 1 m diameter and bursting boiling water at max. 0.5 m height. Forms a N05 tectonic line with P.113 and P.115, and is on N05 fractures P '49,26258'' N 21 24'38,13786'' W Fig. 21a Deildartunga X N X N150 Eye with 1.5 m diameter and bursting boiling water at 1 m height. Forms a N05 tectonic line with P , and is on N05 fractures P.118 Very big eye with 2 m diameter in a separate basin. Form a net N150 tectonic line with P and is on the N150 fracture P '49,32716'' N 21 24'38,15337'' W 64 39'49,52827'' N 21 24'38,00292'' W Fig. 21a Fig. 21a X N06 Steaming eye of 1 cm size lying directly on a N-S fracture on hard altered surface 64 39'49,44776'' N 21 24'38,37514'' W Fig. 21a 118 N150 Host fracture to geothermal points P and possibly P '49,46905'' N 21 24'38,15027'' W Fig. 21a 119 N02 Host fracture to geothermal points P , and possibly P '49,46420'' N 21 24'38,22176'' W Fig. 21a

50 X N150 3 eyes with 0.5 m diameter each and boiling water bursting to 10 cm height. Form a net N150 tectonic line with P.116 and P.121. Is at the intersection of host fractures P.123 (N72 ) and P.122 (N150 ) 64 39'49,55129'' N 21 24'38,00938'' W Fig. 21a X N150 Big bubbling eye. Form a N150 tectonic line with P.120 and P.116. Is on fracture N150 P '49,49646'' N 21 24'37,98095'' W Fig. 21a Deildartunga 122 N Host fracture to P.116 and P Host fracture to P.120, located in the western edge of the concrete basin containing P.116, P '49,44700'' N 21 24'38,01316'' W 64 39'49,54670'' N 21 24'38,07706'' W Fig. 21a Fig. 21a Litla Laug. Concrete basin 1 x 2 m on top of an old hot geothermal spring. Was cooled down and used for cold water 64 39'51,99688'' N 21 24'35,43926'' W Fig X A muddy spot 5 cm diameter in the western part of the ditch by greenhouses 64 39'51,56393'' N 21 24'35,65962'' W

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55 Chapter 5 HURÐARBAK SOUTH

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58 Locality Point (P) Number Max. temperature inside of the structure (in C ) Other temperature inside of the structure (in C ) Temperature in geothermal zone outside of the structure (in C ) White deposition (silica?) Algae Oxidation and possible silica deposition Bubbles Tectonic alignment of the manifestations Comment GPS coordinates Picture Hotter point in a very swampy zone with beginning of algae accumulation. A small stream is connected to it. Could form a N12 line with P.127 and P Hotter point in a very swampy zone with beginning of algae accumulation. A small stream is connected to it. Could form a N12 line with P.126 and P Hotter point in a very swampy zone with beginning of algae accumulation. A small stream is connected to it. Could form a N108 line with P '03,82205'' N 21 24'25,84715'' W 64 41'03,90939'' N 21 24'25,75341'' W 64 41'03,95823'' N 21 24'25,93623'' W Hurðarbak

59 Hotter point in very swampy zone with beginning of algae accumulation. A small stream is connected to it. Could form a N12 line with P and P '04,12462'' N 21 24'25,57412'' W , 9.5, 8.5, 5.5 Hotter point in very swampy zone with beginning of algae accumulation. A small stream is connected to it. Could form a N12 line with P '04,27411'' N 21 24'25,67289'' W Hurðarbak Hotter point in a very swampy zone with beginning of algae accumulation. A small stream is connected to it Outline of the cold geothermal area containing P Includes the only zone of swamp and small stagnant stream with special green vegetation in a frozen surrounding. Soil T at the time of mapping was - 4 C 64 41'04,58639'' N 21 24'24,63638'' W 64 41'04,51623'' N 21 24'24,73420'' W N25 Small deep swampy hole with running water in a frozen surrounding. Greener vegetation associated with the water. Air temperature at the time of measurement was C. Form a line N25 with P '06,32649'' N 21 24'25,72809'' W

60 N25 Cold spring. Small deep swampy hole with running water in a frozen surrounding. Greener vegetation associated with the water. Has some discharge. Air temperature at the time of measurement was C. Form a line N25 with P.133 and P '06,44418'' N 21 24'25,57172'' W Hurðarbak N N25 Cold spring. Small deep swampy hole with running water in a frozen surrounding. Greener vegetation associated with the water. Air temperature at the time of measurement was C. Form a line N25 with P and P Cold spring. Small deep swampy hole with running water in a frozen surrounding. Greener vegetation associated with the water. Air temperature at the time of measurement was C. Form a line N25 with P and P '06,58021'' N 21 24'25,40921'' W 64 41'06,74956'' N 21 24'25,25959'' W N25 Cold spring. Small deep swampy hole with running water in a frozen surrounding. Greener vegetation associated with the water. Air temperature at the time of measurement was C. Form a sharp tectonic lineation N25 with P '06,94193'' N 21 24'25,08690'' W

61 X X X N55 Big perfect eye with 0.5 m diameter and bursting boiling water in a hard altered rock. Form a N55 tectonic line with P '08,79716'' N 21 24'20,53249'' W Fig To the N: 94.2 X N55 Pool with 2 boiling points striking N50 together, and bursting water. Is at some 4 m SW of the green tank. Has discharge. Form a tectonic line N55 with P '08,82243'' N 21 24'20,38795'' W Fig X Outline of the area containing P and the green tank 64 41'08,99089'' N 21 24'20,40013'' W Fig. 24 Hurðarbak X X N50 Circular eye with 30 cm diameter and bursting water Elongated eye N50 with bursting boiling water 64 41'09,03654'' N 21 24'19,77619'' W 64 41'09,00526'' N 21 24'19,72761'' W Fig. 25 Fig X X X X Outline of the area containing P These points are in hard rock and have some discharge 64 41'08,97405'' N 21 24'19,77014'' W Fig X Eye of 0.30 x 0.15 m, in hard rock, with little discharge. Form a net N80 tectonic line with P.145, and with P , P.163, and P '09,22392'' N 21 24'18,23142'' W Fig X Big eye with 1 m diameter, 0.5 cm depth, and little discharge. Form a net tectonic line N80 with P.144 and with P , P.163, and P '09,22967'' N 21 24'18,05540'' W Fig

62 X X X Small eye of 10 x 5 cm, in swampy sediments Eye 25 x 15 cm, in swampy sediments with oxidation. Could form a tectonic line N80 with P '09,70041'' N 21 24'18,29588'' W 64 41'09,71161'' N 21 24'18,01280'' W 148 a 61 X Small eye with 5 cm diameter, in swampy sediments. Form a net N08 tectonic line with P.157 and P.159, P.149, P.148b, and P '09,49152'' N 21 24'17,67238'' W Hurðarbak 148 b cm to the S: m to the N: 37.6, 1 m to the NW: 42.3 X X Small eye in swampy sediments. Form a net N08 tectonic line with P.157 and P.159, P.149, P.148a, and P Hot point in swampy area. Form a net N08 tectonic line with P.157 and P.159, P.148ab, and P '09,47228'' N 21 24'17,50574'' W 64 41'09,40502'' N 21 24'17,65399'' W X Small eye of 10 x 5 cm, in swampy sediments 64 41'09,48053'' N 21 24'17,23626'' W ; 69 X X X N10 3 hot points in a swampy area forming a N10 tectonic line 64 41'09,36772'' N 21 24'17,11311'' W X X X X Big eye with 1 m diameter and 1 m depth in hard rock 64 41'09,50518'' N 21 24'16,54106'' W X Eye with 0.40 m diameter. Could form a N80 tectonic line with P , P , P.163, and P '09,25376'' N 21 24'16,51450'' W Fig

63 Eye with 5 cm diameter. Could form a N80 tectonic line with P.153 and P.155, P , P.163, and P '09,36078'' N 21 24'16,39565'' W Fig Eye with 0.50 m diameter and 0.20 m depth. Could form a N80 tectonic line with P , P , P.163, and P '09,32233'' N 21 24'16,35102'' W Fig Outline of the area containing P '09,30503'' N 21 24'16,10811'' W Hurðarbak , 67.7, 70.2, X X Group of eyes in swampy stream. Form a net N08 tectonic line with P.158 and P.159, P.149, P.148a-b, and P Eye at the N edge of a swampy stream '08,75855'' N 21 24'17,87058'' W 64 41'08,84179'' N 21 24'17,59491'' W cm to the E: 60.4 ; 80 cm to the E: 47.9 X Hot zone in stagnant portion of a stream in swampy sediments. Form a net N08 tectonic line with P , P.149, P.148a-b, and P '08,75854'' N 21 24'17,88606'' W , m to the N: 35.3 Form a net N15 tectonic line with P.162, P , and P '08,84855'' N 21 24'15,52336'' W At 0.5 m and 2 m to the NNW: 48 and 31 ; at 1 m to the SE: 34 Form a net N15 tectonic line with P.160, P , and P '08,93754'' N 21 24'15,47038'' W

64 162 Outline of the area containing P '08,97892'' N 21 24'15,35428'' W , m to the E: 22.5 ; 0.5 m to the N: 23 ; 0.5 m to the W: 38 ; 1 m to the S: 31.3 N18 3 hot points. Could form a N80 tectonic line with P , P , P.163, and P '09,35390'' N 21 24'15,67750'' W Hurðarbak X , 57.4, 78.6, 82 (is P. 164), 67, 63.2, 72.5, 68 Small eye in swampy sediments. Form a net N80 tectonic line with P , P , P.163, and P , and a net N15 tectonic line with P , P.165, and P.168 Eye with 15 cm diameter in swampy sediments. Form a N80 tectonic line with P , P , P.163, and P , and a net N15 tectonic line with P , P.164, and P.168 Outline of the area containing P.P '09,34216'' N 21 24'15,04868'' W 64 41'09,38538'' N 21 24'15,16998'' W 64 41'09,34440'' N 21 24'15,34094'' W Fig. 26 Fig Small pond with 0.50 x 0.30 m size, in swamp 64 41'09,64798'' N 21 24'15,25092'' W X 2 hot points in a swampy area. Form a net N15 tectonic line with P , and P '09,93945'' N 21 24'14,93296'' W

65 , 60, 62.8, 66, 62.3, 72.3, 78, , 39.8, 47.2 Outline of the area containing P '09,97128'' N 21 24'14,88092'' W On a NW- SE line, to the SE: 57.4, 55, 56.2 To the N: 47.5 ; at 10 cm to the NE: 29 ; at 1 m to the S: 38 ; ice at 10 cm to the SE N160 2 small eyes with 5-10 cm diameter 64 41'10,42538'' N 21 24'16,10905'' W Hurðarbak , 46.9 On a N-S line to the S, at 0.5 m, 1.5 m, and 3 m: 47.9, 42.2, 34.5 Small eye in the grass. Form a net N08 tectonic line with P , P.149, P.148a-b, and P.172 In a swampy area. Form a net N08 tectonic line with P , P.149, P.148a-b, and P '10,40897'' N 21 24'17,24222'' W 64 41'10,23961'' N 21 24'17,30539'' W 173 Outline of the area containing P Strikes N '09,23686'' N 21 24'18,44489'' W N130 Cold spring with 1 m diameter and liquid water in a frozen surrounding, outside of the geothermal zone. A stream flows from it northwards but does not reach the geothermal zone. Could be identified due to frozen surrounding ground. Form a line N130 with P '07,23124'' N 21 24'15,40904'' W Fig

66 Eye with 5 cm diameter, on the eastern side of the stream. Heats the water flowing from the cold stream P.174 from here northward 64 41'07,65565'' N 21 24'15,81348'' W Cold spring 1 x 0.5 m diameter, with liquid water in frosty surrounding grassy area. Form a N130 line with P '06,72853'' N 21 24'14,18125'' W Fig Eastern border of the stream flowing from P '07,24984'' N 21 24'15,49162'' W Hurðarbak Western border of the stream flowing from P.174 Outline of the geothermal area containing P '08,73437'' N 21 24'16,00574'' W 64 41'09,13799'' N 21 24'14,61182'' W X X X X Eye with 20 cm diameter, by the edge of the grass. Form a N165 line with P.183, and could be associated with the fracture on P.181. Silica? 64 41'18,20922'' N 21 24'10,00767'' W Fig X X X N165 Big eye with 1 m diameter, and 2 or 3 bursting zones in the middle of a fracture N '18,25083'' N 21 24'09,93121'' W Fig An abandoned wash house, including 2 pipes with steam escaping, indicating the presence of a natural spring underneath. Form a line N165 with P '18,39779'' N 21 24'09,97396'' W Fig

67 T measured at the pipe coming out of the northern part of the house P.182. GPS point indicates the possible position of the spring beneath the central part of the house. Form a line N165 with P '18,45690'' N 21 24'10,09041'' W Fig. 26 Hurðarbak X Small eye with 0.30 m diameter and bursting water in the geothermal stream 64 41'18,81440'' N 21 24'09,56053'' W Fig X X X X N20 Outline of the area containing P Area with swamp and much hard alteration '18,87573'' N 21 24'09,42306'' W Fig Orange pump house 64 41'19,28645'' N 21 24'09,04770'' W Fig

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71 REFERENCES Björnsson H GPS-mapping of the geothermal manifestations in Kleppjárnsreykir, Deildartunga and Hurðarbak South in Borgarfjörður, West Iceland. Cooperative project between the University of Iceland, Faculty of Sciences and Íslenskar orkurannsóknir (Ísor), 48 p. Einarsson, P., Klein, F. W., and Björnsson, S., 1977, The Borgarfjörður earthquakes of 1974 in West Iceland, Bulletin of the Seismological Society of America, 67, p Jóhannesson, H., Sæmundsson, K., Geological map of Iceland 1: Bedrock geology. Náttúrufræðistofnun Íslands. Khodayar, M., and Einarsson, P Strike-slip faulting, normal faulting and lateral dyke injections along a single fault: Field example of the Gljúfurà Fault near a Tertiary oblique rift/transform zone, Borgarfjörður, W-Iceland, Journal of Geophysical Research, Vol. 107, NO. B5, /2001JB000150, (ETG 5, p. 1-18). Khodayar, M., Björnsson, H., Einarsson, P., and Franzson, H GPS-mapping of geothermal areas in West Iceland, Phase 1: Kleppjárnsreykir, Deildartunga, Hurðarbak South in Reykholtsdalur. An overview Short report. Íslenskar orkurannsóknir, ÍSOR-04138, 7 p