川东L2井三叠系飞仙关组碳酸盐样品的锶同位素年龄标定

87Sr/86Sr ratios of the 4 carbonate samples collected from the Feixianguan Formation, Well Luojia 2, Eastern Sichuan were measured. The Sr concentrations of the 4 samples are 1080 to 3100 ppm (average 1795 ppm), Mn 6.2 to 42 ppm (average 16.3 ppm), and Mn/Sr 0.007 to 0.039 (average 0.013), so, it is thought that they contain information on the original seawater strontium isotope composition. According to the principle of strontium isotope stratigraphy, the authors attempt to calibrate the ages of the samples. 4 samples are located at the well depths of 3297.6 m, 3290.0m, 3268.8m and 3201.6m, corresponding 87Sr/86Sr ratios are 0.707330, 0.707340, 0.707348 and 0.707383, and the ages calibrated are 245.3Ma、245.2Ma、245.1Ma和245.0Ma, respectively. The age calibrated of the sample with a depth 3201.6m, because of its higher Mn concentration (42 ppm), has lower reliability, but the ages calibrated from the other 3 samples are believed reliable.