Geochemical proxies: Paleoclimate or paleoenvironment?

Abstract

Complications of interpretations of geochemical proxies used for paleoclimatic constructions, including proxies which may be interpreted as evidence of former glaciations, are more fundamental than is commonly acknowledged. Recent advancements have shown a much larger variation in the geochemical data than expected, and there may be a connection to local geological environments and processes rather than paleoclimate. The data has often been overinterpreted in paleoclimatic models and studies, and more caution is justified when interpreting ancient climates from geochemical proxies. A broader range of reasons for geochemical variations, additional to climate (e.g., source and paleotransport which may help in discovering provenance), should be considered.

Isotopes of carbon, oxygen and strontium, weathering (CIA), ikaites and banded iron formations are reviewed and discussed. Cap carbonates are considered as evidence for warm climate and are commonly covering diamictites that have been interpreted to be glaciogenic, and these are therefore relevant and discussed.