Archaeal hydroxylated isoprenoid GDGTs in Asian lake sediments: A new tool for terrestrial paleotemperature reconstructions

Hydroxylated isoprenoid GDGTs (OH-GDGTs) have emerged as a novel tool for reconstructing sea surface temperatures. However, when using marine OH-GDGT calibration in lacustrine settings, it leads to a significant overestimation of temperatures, emphasizing the necessity for a thorough examination of OH-GDGTs in lakes. Here, we investigated OH-GDGTs distributions in surface sediments from 65 lakes in West China and compiled published global lake and marine OH-GDGT datasets. Among all GDGT-based indices, RI-OH showed the strongest correlation with temperature across global lakes. The RI-OH value was higher in lakes than in marine sediments, likely due to differences in the composition of Group 1.1a thaumarchaeotal species between the two settings. The first global RI-OH temperature calibration for lakes was developed and it addressed the issue of temperature overestimation when applied to both water column and sediment core, highlighting the potential of OH-GDGTs as a new terrestrial paleothermometer.