Fig. 2: Cross-check of low-resolution Sr/Ca data and daily growth rate of the Tridacna sample A114.

a The raw data of Sr/Ca. The blue line is the part with clear daily growth layers from the juvenile stage, about 12 years. b The raw data of daily growth rate (DGR). The thick line is fitted using the smoothing spline model. The number of daily growth layers in each annual cycle is marked below the profile. c The annual layer width obtained from the distance of Sr/Ca minimum value in each annual cycle (blue, solid) and the annual layer width (green, hollow) obtained by summing up the DGR in each year.