| Title | PREDICTING THE EVOLUTION OF RIA-RIA TRAVERTINE DEPOSIT IN THE SIPOHOLON AREA, NORTH SUMATERA USING GEOCHEMISTRY ANALYSIS |
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| Authors | B. Sibarani, J.Y. Sianipar, Mustiatin, Suryantini |
| Year | 2018 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | Geochemistry, Great Sumatran Fault, Ria-Ria, Travertine |
| Abstract | The Ria-Ria travertine occurrences developed in eastern side of Tarutung Basin along Great Sumatran Fault. The distribution of the Ria-Ria travertine deposit is strongly related to the neotectonic attributes. Its presence as the upflow zone, the reconstruction of evolution process and the flow direction will help to investigate the location of reservoir in geothermal system and predict the distribution of Ria-Ria travertine naturally. This paper presents the integration among 13C, 34S, water geochemistry, petrography, XRD and XRF analysis with respect to the morphology of research area, Great Sumatran Fault and source of travertine to depict the genesis and evolution of Ria-Ria travertine deposit. Based on 13Ctravertine analysis, the CO2 attained from Alas Formation Basement decarbonization has formed HCO3-rich liquid. As for the 34SSO4 analysis, the result show there are two possibilities of the origin of sulfur either from magmatic or sedimentary sulphides. The bicarbonate Ria-Ria hot spring as a part of upflow zone of a geothermal system is controlled by Great Sumatran Fault strike-slip and has deposited a travertine area of 0.1 km2 with morphology of fissure ridge and terrace-mound. Based on those morphologies, these thermal springs are predicted to evolve along the fissure ridge and move actively following the NNE-SSW direction. Moreover, the fissure ridge travertine characterized by alternating dominant porous fabric of bedded and banded facies with crystalline vein, is controlled by a normal NNE-SSW trending fault that predicted as the extensional fractures of the Sumatran Fault. It is assumed that the Ria-Ria travertine deposit will be grow continuously to the west area or the footwall area of the extension fault. This is also caused by the very fluctuating depth of water table. |