GDGT-Based Temperature and Precipitation Proxy Calibration for the South American Lowlands

Summary We present results from a proxy calibration study on br- and isoGDGTs in soils from tropical South America. Our study includes both surface soil samples as well as vertical profiles. We find that the brGDGT based temperature proxy is depending on vegetation type and introduce an improved tropical calibration. In addition to the aridity dependence of the ratio between br- and isoGDGTs, we also find that the isoGDGT distribution is aridity dependent, allowing for improved precipitation reconstructions. Finally, we find that the down-profile distribution of brGDGTs remains relatively stable, while large variations in isoGDGT distributions indicate potential biogeochemical-driven changes in archaea communities.