G43B-1043
Glacial-Interglacial sea level reconstruction of the last 570 kyr: Inferences from a new benthic δ18O record of IODP Site U1386 (Gulf of Cadiz)

Thursday, 17 December 2015
Poster Hall (Moscone South)
Stefanie Kaboth1, Lucas Joost Lourens1 and Bas de Boer2, (1)Utrecht University, Utrecht, 3584, Netherlands, (2)Utrecht University, Utrecht, Netherlands
Abstract:
Sea level reconstructions on geological time scales are crucial for our understanding of glacial-interglacial cycles in the past, and thus offer context for current and projected changes.

Global sea-level variations since the last glacial maximum have been well established based on numerous well-dated coral reef terraces and speleothem records. Throughout the Late Pleistocene, the coral and speleothem based data sets become more incomplete and reliable dated sea-level points, though showing the general amplitude of sea-level changes, are insufficient to establish the exact pattern and timing of millennial-scale changes.

To gain further insight into glacial-interglacial sea level variations throughout the Late Pleistocene, we generated a new benthic δ18O record of IODP Site U1386 in the Gulf of Cadiz for the past ~ 570 kyr. Site U1386 is located within the Gulf of Cadiz Contourite Depositional System (CDS). These sediments are characterized by high sedimentation rate (~35 cm/kyr), providing a unique opportunity to study sea level oscillations in high resolution. To estimate ice volume and deep-water temperature changes we used an inverse forward modeling approach based on our benthic δ18O data. The coupled model includes four ice-sheet-shelf components that simulate glaciation on Eurasia, North America, Greenland and Antarctica, thereby explicitly accounting for all individual ice-volume contributions throughout the investigated time period.

Our initial findings suggest that older glacial periods were characterized by repeated and substantial δ18O enrichment events preceding their respective glacial maximum. We argue that the observed δ18O enrichment events are not an expression of local hydrographic changes of salinity and/or temperature limited to the Gulf of Cadiz but probably relate to global ice volume changes. In this regard, our results contrast estimates derived from the global mean benthic δ18O LR04 stack. On a regional scale, our results show similarities to recently published sea-level estimates from the Red Sea and Mediterranean Sea.

The in-depth correlation of our initial findings with existing open ocean and regional sea level estimates for the last ~ 570 kyr provides new insights into the sea level evolution on glacial-interglacial timescales.