A preliminary analysis of the formation of travertine and travertine cones in the Jifei hot spring, Yunnan, China

摘要

The Jifei hot spring emerges in the form of a spring group in the Tibet-Yunnan geothermal zone, southwest of Yunnan Province, China. The temperatures of spring waters range from 35 to 81℃ and are mainly of HCO_3-Na-Ca type. The total discharge of the hot spring is about 10 L/s. The spring is characterized by its huge travertine terrace with an area of about 4,000 m~2 and as many as 18 travertine cones of different sizes. The tallest travertine cone is as high as 7.1 m. The travertine formation and evolution can be divided into three periods: travertine terrace deposition period, travertine cone formation period and death period. The hydrochemical characteristics of the Jifei hot spring was analyzed and compared with a local non-travertine hot spring and six other famous travertine springs. The results indicate that the necessary hydrochemical conditions of travertine and travertine cones deposition in the Jifei area are (1) high concentration of HCO_3~- and CO_2; (2) about 52.9% deep source CO_2 with significantly high P_(co)_2 value; (3) very high milliequivalent percentage of HCO_3~- (97.4%) with not very high milliequivalent percentage of Ca~(2+) (24.4%); and (4) a large saturation index of calcite and aragonite of the hot water.