* Corresponding Author
INVESTIGATION OF DISSOLVED SULPHATE IN VARIOUS GEOTHERMAL FIELDS OF SUMATRA USING OXYGEN AND SULPHUR ISOTOPES
https://doi.org/10.22146/ijc.21756 E. Ristin Pujiindiyati(1*), Zainal Abidin(2)
(1) Center for the Application of Isotopes and Radiation Technology, National Nuclear Energy Agency, Jln. Cinere Pasar Jum’at PO.Box 7002 JKSKL, Jakarta 12070
(2) Center for the Application of Isotopes and Radiation Technology, National Nuclear Energy Agency, Jln. Cinere Pasar Jum’at PO.Box 7002 JKSKL, Jakarta 12070
(*) Corresponding Author
Abstract
There are at least 30 high temperature systems; eleven active volcanoes, five degassing volcanoes and one caldera volcano controlled by Sumatra Fault Zone over a length of 1700 km. To understand this geothermal field system, some information about geochemistry including isotope composition in its fluid is needed. Sulphur-34 and oxygen-18 isotopes in dissolved sulphate pair have been used to determine the origin of acidic fluid of sulphate and to evaluate the process involved. The fluids from eight hot springs, two fumaroles, four deep wells and crater have been collected in along Sumatra geothermal fields. Sulphur-34 (d 34S (SO4), 0/00 CDT) and oxygen-18 (d 18O (SO4), 0/00 SMOW) in sulphate is analyzed according to Robinson-Kusakabe and Rafter method, respectively. The d 34S (SO4) values from Sibayak wells are more enriched of 16.8 0/00 to 18.2 0/0 that may indicate the dissolution of anhydrite minerals or isotope partitioning in hydration of SO2. The d 34S (SO4) values from two fumaroles (Pusuk Bukit - North Sumatra and Rantau Dadap - South Sumatra) are at depleted value of -0.150/00 and 1.80/00, those are close to d 34S from magmatic sulphur. In general, the d 34S (SO4) of springs spread in a wide range of 5.250/00 to14.20/00 and show a mixing process between atmospheric sulphate and sulphate from deep wells. The d 18O (SO4) from wells exhibits depleted value around -3.60/00 suggesting that 87.5% of sulphate oxygen is derived from groundwater oxygen and 12.5% is derived from atmospheric molecular oxygen in sulphide oxidation reaction. In the other hand, hot springs (except Semurup), crater and fumaroles have enriched value of d 18O (SO4). These enriched values suggest that a higher percentage of atmospherically derived oxygen compared to those from the depth.
Keywords
Full Text:
Full Text PdfReferences
[1] Hochstein, M.P., and Sayogi, S., 1993, Geothermics, 22, 3, 181-200.
[2] IAEA, 1981., “Geothermal waters” in Stable Isotope in Hydrology-Technical Report Series 210, International Atomic Energy Agency, Vienna, 241
[3] Robinson, B.W.,1987, Proceedings of an advisory group meeting at 17-20 June 1985, International Atomic Energy Agency, Vienna, 31-47
[4] Hoefs, J., 1980, Stable Isotope Geochemistry, Springer-Verlag, Berlin, 18.
[5] Epstein, S., and Mayeda, T.K., 1959, Geochim. Cosmochim Acta, 4, 10, 213-224
[6] Rafter, T.A., 1967, New Zealand J. Sci.,10, 493-510
[7] Robinson, B.W., and Kusakabe, M., 1975, Anal. Chem., 47, 7, 1179-1181
[8] Ohmoto, H., and Lasaga, A.C., 1986, Geochim. Cosmochim Acta, 46, 1727-1745
[9] Clark, I., and Fritz, P., 1997, “Groundwater Quality” in Environmental Isotopes in Hydrogeology”, Lewis Publishers, Boca-Ratan-New York, 137
[10] Gigenbach, W.F., and Corrales, S.R., 1992, Appl. Geochem, 7, 14, 309-332.
[11] Krouse, H.R., 1987, Proceeding of an advisory group meeting at 17-20 June 1985, International Atomic Energy Agency , Vienna,19-20
[12] Krouse, H.R., and Van Everdingen, R., 1985, Nature, 315, 395-396
[13] Taylor, B.C., Wheeler, M.C., and Nordstorm, D.K ., 1984, Nature, 308, 538-541
DOI: https://doi.org/10.22146/ijc.21756
Article Metrics
Abstract views : 1302
| 
views : 1442
Copyright (c) 2010 Indonesian Journal of Chemistry
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
Indonesian Journal of Chemistry (ISSN 1411-9420 /e-ISSN 2460-1578) - Chemistry Department, Universitas Gadjah Mada, Indonesia.