US Geological Survey


Date of this Version



Quaternary Science Reviews 21 (2002) 1521–1539


A simple hydrologic-isotopic-balance (HIBAL) model for application to paleolake δ18O records is presented. Inputs to the model include discharge, on-lake precipitation, evaporation, and the δ18O values of these fluid fluxes. Monthly values of climatic parameters that govern the fractionation of 18O and 16O during evaporation have been extracted from historical data sets and held constant in the model. The ability of the model to simulate changes in the hydrologic balance and the δ18O evolution of the mixed layer has been demonstrated using measured data from Pyramid Lake, Nevada. Simulations of the response in δ18O to step- and periodic-function changes in fluid inputs indicate that the hydrologic balance and δ18O values lag climate change. Input of reconstructe driver discharges and their δ18O values to Pyramid and Walker lakes indicates that minima and maxima in simulated δ18O records correspond to minima and maxima in the reconstructed volume records and that the overall shape of the volume and δ18O records is similar. The model was also used in a simulation of abrupt oscillations in the δ18O values of paleo-Owens Lake, California.