美国西尔斯盐湖钙华研究综述

Tufa has a scientific research value. There are wide distributions of the tufa mounds in the north, middle and southwest of Searles Lake, California, USA. The tufa mounds range from a few centimeters to 45 m in height, and most are 5 to 12 m high. There are four tufa facies can be identified from the mounds, including porous spongy tufa facies, nodular tufa facies, columnar tufa facies and finely-laminated crusts tufa facies. In terms of tempo-spatial distribution, there are two sequences of tufa deposition, including porous spongy tufa facies to nodular tufa facies to finely-laminated crusts tufa facies to porous spongy tufa facies and porous spongy tufa facies to columnar tufa facies to finely-laminated crusts tufa facies to porous spongy tufa facies. These tufa mounds mainly consist of calcite and aragonite. On the microscopic scale, these tufa facies dominantly make up nano-shperes and rod-like crystals, interpreted to be the activities of microorganism, such as bacterial. The values of δ13C in the tufa facies were measured, and the results were positive, proving that the tufa of Searles Lake is the thermogene tufa. The discussion on the main sedimentary types and genesis of tufa in Searles Lake can provide comparative reference for the study of tufa in China.