Gulf of Alaska Holocene paleoceanography and paleoclimatology from diatom proxies in core EW0408-22JC, Crawfish Inlet, Baranof Island, Alaska.

Abstract:

Diatom ecology is used in this study as a paleoceanographic and paleoclimatic proxy for the Eastern Gulf of Alaska. Core EW0408-22JC, an 11.84 m long piston core, was retrieved in 2004 from 188 m water depth in Crawfish Inlet, a deglaciated fjord of Baranof Island, Southeast Alaska, which opens to the eastern Gulf of Alaska (GOA). The core contains a nearly complete Holocene record constrained by ¹⁴C and tephrochronology with relatively high sedimentation rates of ~100-200 cm/ky, favorable to high-resolution climate investigations. High-resolution geochemical measurements indicate increasing opal and total organic concentrations and decreasing lithic and CaCO₃ concentrations from early to late Holocene. Diatom ecology is quantified by counting of diatom taxa at approximately 170-year stratigraphic intervals, and evaluated for climatic and oceanographic significance using the modern analog technique (MAT) and factor analysis. Diatom proxy variability from this site is inferred to result from changes within the GOA climatic and oceanographic regime. Within this region, the strength and positioning of the Aleutian Low and the Alaska Current influence oceanographic parameters including sea surface temperature, downwelling, and nutrient availability, all of which are reflected in diatom ecology fluctuations. The adjacent North American terrestrial hydroclimate is largely controlled by these factors, and its past conditions are inferred by this reconstruction of GOA paleoceanography and paleoclimatology.