Abstract
A marine sediment record from the central Bering Sea, spanning the last 20 thousand years (ka), was studied to unravel the depositional history with regard to terrigenous sediment supply and biogenic sedimentation. Methodic approaches comprised the inference of accumulation rates of siliciclastic and biogenic components, grain-size analysis, and (clay) mineralogy, as well as paleoclimatic modelling. Changes in the depositional history provides insight into land-ocean linkages of paleoenvironmental changes. During the finale of the Last Glacial Maximum, the depositional environment was characterized by hemipelagic background sedimentation. A marked change in the terrigenous sediment provenance during the late Heinrich 1 Stadial (15.7–14.5 ka), indicated by increases in kaolinite and a high glaciofluvial influx of clay, gives evidence of the deglaciation of the Brooks Range in the hinterland of Alaska. This meltwater pulse also stimulated the postglacial onset of biological productivity. Glacial melt implies regional climate warming during a time of widespread cooling on the northern hemisphere. Our simulation experiment with a coupled climate model suggests atmospheric teleconnections to the North Atlantic, with impacts on the dynamics of the Aleutian Low system that gave rise to warmer winters and an early onset of spring during that time. The late deglacial period between 14.5 and 11.0 ka was characterized by enhanced fluvial runoff and biological productivity in the course of climate amelioration, sea-level rise, seasonal sea-ice retreat, and permafrost thaw in the hinterland. The latter processes temporarily stalled during the Younger Dryas stadial (12.9-11.7 ka) and commenced again during the Preboreal (earliest Holocene), after 11.7 ka. High river runoff might have fertilized the Bering Sea and contributed to enhanced upper ocean stratification. Since 11.0 ka, advanced transgression has shifted the coast line and fluvial influence of the Yukon River away from the study site. The opening of the Bering Strait strengthened contour currents along the continental slope, leaving behind winnowed sand-rich sediments through the early to mid-Holocene, with non-deposition occurring since about 6.0 ka.
Highlights
Climate variability during the late Quaternary was characterized by strong insolation-driven contrasts between interglacial and glacial stages, documented by the repeated built-up and decay of northern-hemispheric ice sheets (e.g., Dyke, 2004; Gowan et al, 2021)
The investigated sediment section comprises the time between 20 and 6 ka (Figure 2). This time interval spans the late part of the Last Glacial Maximum (LGM: 23—19 ka), the early Deglacial (ED: 19–17.1 ka), Heinrich Stadial 1 (HS1: 17.1–14.7 ka, the Bølling-Allerød Interstadial (B/A: 14.7–12.9 ka), the Younger Dryas stadial (YD: 12.9–11.7 ka), the Preboreal (PB: 11.7–10.6 ka, as oldest part of the Holocene), and the remaining Holocene (< 10.6 ka)
To explore the HS1-to-LGM changes of surface air temperatures and surface winds associated with the Aleutian Low-pressure system, we have re-analyzed results obtained from model set-ups encompassing the pre-industrial (PI) (Wei and Lohmann, 2012), LGM and glacial hosing experiments (Gong et al, 2013; Zhang et al, 2013)
Summary
Climate variability during the late Quaternary was characterized by strong insolation-driven contrasts between interglacial and glacial stages, documented by the repeated built-up and decay of northern-hemispheric ice sheets (e.g., Dyke, 2004; Gowan et al, 2021). The time intervals between conditions of glacial maxima and interglacial climate optima are considered as transitions between climate extremes, referred to as terminations These terminations are of particular interest, as they are often affected by non-linear responses to external climate forcing and show complex environmental interactions with threshold feedbacks in the climate system (Clark et al, 2012; Lohmann et al, 2020). During the last decades, increasing attention has been given to the paleooceanography of the North Pacific and its marginal seas, where interacting dynamic processes of water-mass formation, ocean stratification, sea-level fluctuations, biological productivity, seaice formation, and fresh-water pulses show global connections as integral part of the global MOC and via atmospheric teleconnections (Cook et al, 2005; Diekmann et al, 2008; Takahashi et al, 2011; Gersonde, 2012; Max et al, 2014; Pelto et al, 2018; Lohmann et al, 2019; Davis et al, 2020; Praetorius et al, 2020)
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call