Stalagmite evidence of Last Glacial Maximum to early Holocene climate variability in southwestern Iran

Glacial periods and their terminations are useful for assessing the full scale of natural climate variability in the diverse climate regions of West Asia (i.e. deserts, mountains, alluvial plains, coastal zones). In this study, we report the first stalagmite stable isotope (delta O-18 and delta C-13) records from the southern Zagros Mountains in southwest Iran. The records partially span the period from the Last Glacial Maximum (LGM) to the early Holocene, 24.2-9.6 thousand years before the present. The southwest Iran stalagmite delta O-18 and delta C-13 records indicate that climate and environment in the area differed substantially between the LGM and early Holocene. High stalagmite delta C-13 values are found at the LGM (7 parts per thousand greater compared to the early Holocene), and are attributed to sparse vegetation and reduced soil bio-productivity, and possibly a greater degree of prior calcite precipitation in the epikarst, as a result of a cold and dry climate. Stalagmite delta O-18 values are also high at the LGM (4 parts per thousand greater compared to the early Holocene), and are attributed to lower temperatures (larger water-calcite isotope fractionation) and higher delta O-18 values of the moisture sources (Mediterranean and Red Seas). Through the deglaciation, stalagmite delta O-18, delta C-13 and/or growth features coincide with the North Atlantic Heinrich Stadial 1, the Bolling-Allerod warm period and the Younger Dryas cold event, supporting a relationship between southern Zagros climate and the North Atlantic millennial events.