韓国の温泉水の水素,酸素及び硫黄同位体比 [in Japanese] A Study on hydrogen, oxygen and sulfur isotopic ratios of the hot spring waters in South Korea [in Japanese]
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All hot spring waters of non-volcanic origin are mostly distributed in the plutonic masses of the Cretaceous Bulkuksa granites and the Jurassic Daebo granites in the central and southeastern parts of the Korean peninsula. Temperature and pH of the hot spring waters range from 28.5° to 67℃ and from 6.55 to 9.40, respectively. Dongrae and Haiundae hot springs are located on or near the fault line, but others are not directly related to the fault structures. The ranges of δ<sup>18</sup>O and δD values for the hot spring waters are from -6.5 to -10.7‰ and -48.7 to -73.8‰, respectively, and for the local surface waters from -5.5 to -10.1‰ and -39.5 to -70.7‰, respectively. On the basis of stable isotopic and chemical compositions of the hot spring waters and geographical distribution of the hot springs in Korea, the hot spring waters can be divided into following three types; (1) Backam type characterized by low δ<sup>18</sup>O and δD values and alkaline waters. (2) Onyang type with weakly alkaline and intermediate isotopic values. Relatively high content of F<sup>-</sup> and low Na<sup>+</sup>, Cl<sup>-</sup>, and SO<sub>4</sub><sup>2-</sup> contents. (3) Haiundae type, having high δ<sup>18</sup>O and δD values, weakly alkaline, and high concentration of Na<sup>+</sup>, K<sup>+</sup>, Ca<sup>2+</sup>, Cl<sup>-</sup> and SO<sub>4</sub><sup>2-</sup>. Most of the oxygen and hydrogen isotopic values are plotted slightly below the meteoric and surface water line defined by CRAIG (1961), and show a gradual decrease of the heavy isotope concentration from south to north, and west to east in the penin- sula possibly due to temperature and altitude effects. The hot spring waters are characterized by δ<sup>18</sup>O and δD values that are lower than those of the local surface waters at or near the hot springs, suggesting that the hot spring waters are derived from geographically further northern districts and topogra- phically higher mountain regions. The δ<sup>34</sup>S values of dissolved sulfates range from +5.5 to +29.3‰, apparently reflecting the different sources of the sulfates for different hot springs. Sulfates of the hot spring waters from Haiundae and Pohang may be originated from sea water sulfate and those from Yusung, Duggu and Echon from the secondary sulfate produced by oxidation of sulfide minerals and the mixtures of the above two are thought to be responsible for Suanbo, Duksan, Dongrae, Magumsam and Chucksan hot springs.
Chikyukagaku 15(1), 6-16, 1981
The Geochemical Society of Japan