Indian Journal of Marine Sciences Vol. 37(2), June 2008, pp. 166-180 Composition and origin of modern hydrothermal systems of the Kuril island arc O. Chudaev1, V. Chudaeva2, K. Sugimori3, A. Kuno4, M. Matsuo4 1Far East Geological Institute, FEB RAS, Vladivostok, Russia 2Pacific Institute of Geography, FEB RAS, Vladivostok, Russia 3Toho University, Tokyo, Japan 4Tokyo University, Tokyo, Japan Received on 11 January 2008; revised 22 May 2008 The resent study consists the original geochemical data on the thermal waters of the Kuril Islands (Mendeleev, Golovnin, and Ebeko volcanoes) and relation between thermal waters and ore formation. Among the thermal water types three main groups can be distinguished: sodium–chloride, acid sulfate and chloride-sulfate-bicarbonate. The contents and behaviors of siderophile, chalcophile, lithophile, and rare-earth elements are discussed. These data, together with the result of isotopic studies, enumerates the origin of these waters. The high-temperature sodium-chloride waters have a profound effect on the formation of copper-pyrite mineralization on Mendeleev, Ebeko and Baransky volcanoes. The acid waters influence the processes of hypergenic ore formation Key words: geochemistry of thermal waters, stable isotopes, ore formation, Kuril Islands Introduction compounds, and the rest are aluminum, iron, zinc, The Kuril island arc is a natural extension of the copper, among others. These elements form a geological structure of southern Kamchatka where the significant mass of suspended matter on a Pacific Plate is subducting under the Kamchatka geochemical barrier in the shelf zone of the sea. The Peninsula and the Kuril Islands. Intensive volcanic ore accumulation is related with modern hydrothermal and hydrothermal activity started in the Late systems not only at depth but also on the surface. The Cretaceous, continuing until the present, and has information on the geochemistry of hydrothermal resulted in about 100 known ore deposits of copper, systems is limited, and the most reasonable results zinc, lead, native sulfur, iron, and molybdenum. The were obtained in the 1970’s and the Kuril island arc is the second location in the world 1990’s3,4,6,7,8,9,10,11,12. This paper, consists the results where native rhenium sulfide has been found. Due to on trace and rare elements as well as data on H, O, S, active modern hydrothermal activity deposits of and He isotope ratios for the hydrothermal systems of copper-porphyry type are forming at a depth of 1.5-2 Kunashir, Iturup, and Paramushir Islands. This also km within the volcanoes Ebeko (Paramushir Island), consists discuss the problems of geochemical zoning Baransky (Iturup Island)1,2 and Mendeleev (Kunashir of hydrothermal systems and their role in ore Island)3. In addition, huge masses of chemical formation. elements are supplied to the day surface to the hypergenesis zone from discharging thermal waters, Study Area and in the process the migration capacity of many The Kuril Islands are located between latitudes of chemical elements is sharply changed on their 43o26” and 50o56” North and extend for 1250 km as a migration way. The studies of K.K. Zelenov (1972) continuous ridge from southwest to northeast (Fig. 1). and S.M. Fazlulin (1999), reveals that the Kislyi In the south they are separated from Hokkaido Creek of Mendeleev Volcano, , supplies more than Island by the Kunashir Strait and in the north they 500 kg of aluminum and 200 kg of iron and other border Kamchatka Peninsula on the First Kuril Strait. chemical elements to the Pacific Ocean4,5 per day. Geographically, the Kuril Islands form an arc facing The Ebeko Volcano supplies about 365 tons of the Pacific Ocean and are separated from it by a deep- dissolved matter to the Okhotsk Sea per day. This sea trench. It have 85 volcanoes, 39 of which are matter consists about eighty percentage of silica active. CHUDAEV et al.: COMPOSITION AND ORIGIN OF MODERN HYDROTHERMAL SYSTEM OF KURIL ISLAND 167 The Kuril Islands were volcanically activate during There are many thermal waters variety related with the Cenozoic. Volcanic activity resulted in four Mendeleev Volcano. The present study is related to volcanic complexes: green tuff (Early-Middle the hot springs discharging along the Kislyi and Miocene); volcanogenic-cherty-diatomite; basalt Doktorsky Creeks and the holes of the “Goryachiy 13 (Late Pliocene); and Q4 andesite . The formation of Plyazh” deposit. The samples were also collected the latter is related with intensive gas-hydrothermal from Hole 101, 103, 202 has been sampled (Fig.3). activity, which manifests itself in numerous thermal Golovnin Volcano is in the southern part of springs, steam-gas streams, mud pots, solfataras, and Kunashir Island (Fig.1). It represents a strongly mofettes. The original geochemical data on the truncated cone with a caldera about 4 km in diameter. composition of thermal waters that had collected in A significant part of the caldera is occupied by Lake 2001-2006 on volcanoes of Mendeleev, Golovnin Goryachee, which is connected with small Lake (Kunashir Island), Baransky (Iturup Island), and Kipyashchee by a stream. The water level of the lake Ebeko (Paramushir Island), had been presented Fig. 1. is at 150 m above the sea level. In the caldera two The Kunashir Island is known for several young domes are situated a short distance from each other. volcanic edifices. They are at the stage of gas- They are composed of andesite-dacites. Active hydrothermal activity. These are Golovnin Volcano in solfataras fields are restricted to the domes (Fig. 4). the south, Mendeleev Volcano in the middle part, and The hydrothermal shows related with both Ruruy Volcano in the north (Fig. 1). The present extrusions had been examined . The main discharges study consists the thermal waters connected with of springs in this island are connected with Baransky Mendeleev and Golovnin volcanoes. Mendeleev Volcano of 1126 m high. Its crater is 650 m in Volcano is a volcano of the central type and is diameter, and its walls are composed of andesites. composed of interbanding andesite-basalts and Schematic section of Baranskiy Volcano is given after pyroclastic rocks. The extrusive dome, pronounced in Znamensky V.S. and Nikitina I.B. (1985)11 is shown the relief, is made up of dacites. The horizon of fresh as Fig. 5. infiltration waters is thin on the volcanos slope and The crater on the southwestern slope of the volcano depends strongly on precipitation amounts. Towards at a height of 700 m, looks like a destroyed the slope basement, the horizon thickness increases amphitheatre. There are springs outflows and mud (Fig. 2). pots below this crator laong a creak. The Baransky Volcano area have outcrops of Miocene tuffs and breccias, Pliocene tuffs, Lower Pleistocene marine Fig. 2―Schematic geological-hydrogeological section of Mendeleev Volcano (Baskov, Surikov, 1989). 1 – pyroclastic deposits and andesite lavas; 2 – tuffs, basaltic lavas; 3 – tuffs, lavas of liparites; 4 – neck volcanic formations; 5 – granitoids; 6 – liparite extrusions; 7 – dacite neck; 8 – Cu- porphyry manifistations; 9 – faults; 10-12 – underground waters: 10 – fresh waters, 11 – alkaline sodium-chloride waters, 12 – acid sulfate and chloride waters; 13 – emanations along faults; 14 – boundaries of hydrochemical zones; 15 – fumarole fields with Fig. 1―The study objects of the Kuril island ark. acid waters; 16 – level of ground waters. 168 INDIAN J. MAR. SCI., VOL. 37, NO. 2, JUNE 2008 deposits, and Middle Pleistocene andesites and andesite-basalts. Tuffs and pumices are common in the Sernaya River basin,. According to T.K. Zlobin and V.S. Znamensky (1991), the magmatic chamber may be at a depth of about 5 km14. The springs outflows, related with the volcano, as well as the Reidovskie manifestations localized near the same- named settlement on the periphery of Baransky Volcano had been examined as a part of this study. Ebeko Volcano is a member of the volcano chain, which forms the Vernadsky volcanic ridge, and is the most active volcano (Fig. 6). Fig. 5―Geological section of Baransky Volcano (Znamensky, Nikitina, 1975) 1 – rocks of Neogene basement; 2 – caldera volcanogene- Fig. 3―Location of the studied springs and holes on Mendeleev sedimentary deposits; 3 – stratified bed of andesites and tuffs; 4 – Volcano Pleistocene dacites; 5 – sediments with ore minerals; 6 – 1 – alluvial and marine deposits; 2 – talus and proluvium deposits; Pleistocene andesites and basalts; 7 – Holocene dacites; 8 – faults; 3 – pyroclasts; 4 – tuffs of acid composition; 5 – andesites, 9 – sea level. andesite-basalts; 6 – liparites; 7 – solfatara fields; 8 – area of thermal water discharge; 9 – sampled holes; 10 – sampled springs; 11 – dislocations with break in continuity. Note: Sketch by L.M. Lebedev and I.B. Nikitina (1977) have been used. Fig. 6―Schematic map of the Paramushir north part (after Leonov, 1998, and Belousov et al., 2002) 1 – alluvial marine and lake deposits; 2 – lavas of andesites and 4 andesite-basalts (Q4); 3 – glacial deposits (Q3 ); 4 – lavas of Fig. 4―Location of water and gas sampling on Golovnin Volcano andesite composition (Q3); 5 – lavas of andesite and andesite- 2 1-3 – crater-lake deposits: 1 – 0.5-1 m high; 2 – 2-3 m high; 3 – 8- basalt composition (N2 -Q1); 7 – non-separated volcanogene- 2 10 m high; 4 – andesite-dacites of the extrusive dome; 5 – sedimentary deposits (N1 -N2); 8 – centers of volcanic eruptions opalized rocks; 6 – gas emanations; 7 – sampled manifestations of (arrows show direction of lava flows); 9 – small volcanoes and thermal waters and gases; 8 – terrace cusp scoria cones of the Vernadsky Ridge; 10 – scarps and boundaries Note: Sketch by L.M. Lebedev and I.B. Nikitina (1977) have been of erosive calderas; 11 – thermal springs (a) and fumaroles (b); 12 used. – holes and their numbers. CHUDAEV et al.: COMPOSITION AND ORIGIN OF MODERN HYDROTHERMAL SYSTEM OF KURIL ISLAND 169 It is composed of young lavas of two-pyroxene thermal springs in its apical part confirms this fact.