馬來西亞半島溫泉水中溶解氣和水化學之研究

Abstract

馬來西亞半島所在的巽他(Sunda)板塊是處於澳洲大陸板塊與歐亞大陸板塊交界處。本研究利用水化學和氣體地球化學來討論溫泉水的來源和來源模式。在馬來西亞半島這個無火山地區上就發現了超過60個溫泉，而本研究取其中的十八處溫泉進行採樣。溫泉的測量例如pH值，溫度和導電度都在現地分析。所選溫泉的溫度介於40.1°C 到88.7°C，pH值也在6.6到9.1之間。溫泉的導電度從最小的200 µs/cm 到 最大的43000 µs/cm不等。利用罐頂空間進行一般溶解氣體如氮氣，甲烷和二氧化碳的分析。三端源圖顯示大多樣品都富集氮氣，只有少數樣品含有二氧化碳的成分；水氡是由可攜帶的RAD7氡氣分析儀器作現地測量。馬來西亞半島溫泉的水氡值介於200 Bq/m3和111866 Bq/m3 之間。水氡分析結果顯示馬來西亞半島溫泉的來源和深埋地底的花崗岩體有關；另外取樣品封存於高真空的玻璃瓶中，進行氦同位素比值、氦氖比值研究。氦同位素比值分析結果發現，馬來西亞半島溫泉大多小於0.1Ra而大於0.02Ra（Ra為大氣中3He/4He的比值），說明氦氣屬於地殼來源和上部地函來源的混合；氫氧同位素和陰陽離子的分析結果把馬來西亞半島的溫泉來源分成了天水來源和天水混合海水來源。另外，本研究認為馬來西亞半島溫泉的加熱源來自於冷卻中的花崗岩體和富含鈾釷元素的花崗岩體不斷放射性衰變之下產生的熱量。

Peninsular Malaysia is located on Sunda Plate which is situated between two major boundaries of tectonic plates, the Australian Plate and the Eurasian Plate. Over sixty thermal springs had been reported in Peninsular Malaysia, a non-volcanic country. In this study, eighteen spring samples have been analysed, from which the piper plot and meteoric water line is constructed. Moreover, helium isotopic analyses, dissolved gas analyses and radon activity analyses are also carried out in order to investigate the origin and sources of thermal springs in Peninsular Malaysia. The surface temperature of selected thermal springs ranges from 40.1°C to 88.7°C, the pH values range from 6.6 to 9.1, and the conductivity varies between 200 µs/cm and 43000 µs/cm. The radon activity analyses had been carried out by using RAD7 Radon Detector. Result shows that the radon value of selected thermal springs in Peninsular Malaysia fluctuates within highest value of 111,866 Bq/cm3 and lowest value of 200 Bq/cm3. As for the dissolved gas in thermal springs, nitrogen is the major component and argon, carbon dioxide and oxygen are minor constituents. Isotopic composition of hydrogen (D/H) and oxygen (18O/16O) mostly fall along the local meteoric water line, indicating that the meteoric water is the major fluid source for thermal springs. Meanwhile, the helium isotopic ratios of most samples (except HS 12) show consistently low values, less than 0.1 Ra (Ra is the 3He/4He ratio of the air). It implies that crust component is the major helium gas source for thermal springs, except sample of HS 12 which may involve upper mantle component.