Article ID Journal Published Year Pages File Type
4680847 Earth and Planetary Science Letters 2006 14 Pages PDF
Abstract

Past changes in the seasonal distribution of insolation across the Earth's surface are thought to play a critical role in Quaternary climate cycles. In this study we use Sr/Ca and δ18O as geochemical proxies in the skeleton of a fossil Porites coral to reconstruct the seasonal cycle of sea surface temperature (SST) at Henderson Island, southeast Pacific (24°S, 128°W) during the Marine Isotope Stage (MIS) 9 interglacial (∼ 339–303 ka). Previously-published closed-system U-series ages provide broad age constraints for the timing of reef growth for this unit on Henderson Island, ranging between 334 and 306 ka. We apply published δ18O-SST slope relationships to the stacked δ18O annual cycle in the fossil Porites, and find the amplitude of the seasonal cycle of SST recorded by the MIS 9 coral to be ∼ 4.1 ± 0.57°C, which agrees within error with the modern seasonal cycle of SST (∼ 4.1°C). Sr/Ca-SST slope relationships applied to the fossil Porites stacked Sr/Ca annual cycle suggest the amplitude of the seasonal cycle of SST was ∼ 4.7 ± 0.75°C, exceeding the modern cycle by ∼ 15%, but within error of the modern value. Taken together, these results suggest the seasonal cycle of SST at Henderson Island during MIS 9 equaled or exceeded the modern amplitude. Using modern latitudinal relationships between insolation seasonality and SST seasonality, we present a new application for SST amplitudes reconstructed from fossil corals that can be used in conjunction with U-series ages to provide additional geochronological constraints on the development of open-ocean, interglacial reefs.

Related Topics
Physical Sciences and Engineering Earth and Planetary Sciences Earth and Planetary Sciences (General)
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