L. C. Cleaveland

Preservation of the alkenone paleotemperature proxy in uplifted marine sequences: A test from the Vrica outcrop, Crotone, Italy

The alkenone organic paleotemperature proxy has been used with great success to generate sea-surface temperature (SST) records from diverse areas of the world ocean. To date, however, this methodology has been applied almost exclusively to unconsolidated marine sediments; the fidelity of alkenone preservation in lithified, uplifted marine sequences exposed on land has not been explicitly investigated. Such sedimentary sequences have been buried at depths of hundreds of meters to kilometers before uplift, and in addition have been exposed to oxic pore fluids and subaerial weathering upon ascent to the surface, any of which may cause alteration of biomarker compounds. In this study, we compare alkenone SST estimates from the Vrica land section in Crotone, Italy, with alkenone SST estimates derived from coeval marine sediments retrieved at Ocean Drilling Program Site 964, which is ~300 km offshore of the Vrica location. We find that SST records from the land and marine sections are well correlated, showing similar mean values, cyclicity, and amplitudes. Although results from different sedimentary sequences might depend on the lithologies, burial depths, and weathering histories of individual outcrops, this study suggests that it will be possible to reconstruct quantitative SST histories from marine strata exposed on land.