Heat Flow in the Western Arctic Ocean (Amerasian Basin)

Abstract

From 1963 to 1973 the U.S. Geological Survey measured heat flow at 356 sites in the Amerasian Basin (Western Arctic Ocean) from a drifting ice island (T‐3). The resulting measurements, which are unevenly distributed on Alpha‐Mendeleev Ridge and in Canada and Nautilus Basins, greatly expand available heat flow data for the Arctic Ocean. Average T‐3 heat flow is ~54.7 ± 11.3 mW/m2, and Nautilus Basin is the only well‐surveyed area (~13% of data) with significantly higher average heat flow (63.8 mW/m2). Heat flow and bathymetry are not correlated at a large scale, and turbiditic surficial sediments (Canada and Nautilus Basins) have higher heat flow than the sediments that blanket the Alpha‐Mendeleev Ridge. Thermal gradients are mostly near‐linear, implying that conductive heat transport dominates and that near‐seafloor sediments are in thermal equilibrium with overlying bottom waters. Combining the heat flow data with modern seismic imagery suggests that some of the observed heat flow variability may be explained by local changes in lithology or the presence of basement faults that channel circulating seawater. A numerical model that incorporates thermal conductivity variations along a profile from Canada Basin (thick sediment on mostly oceanic crust) to Alpha Ridge (thin sediment over thick magmatic units associated with the High Arctic Large Igneous Province) predicts heat flow slightly lower than that observed on Alpha Ridge. This, along with other observations, implies that circulating fluids modulate conductive heat flow and contribute to high variability in the T‐3 data set.

Heat Flow on the U.S. Beaufort Margin, Arctic Ocean: Implications for Ocean Warming, Methane Hydrate Stability, and Regional Tectonics

“…The 14 thermal conductivity measurements along transect 1 average 1.14 ± 0.12 W/m/K (Table 1). These values are consistent with previous thermal conductivity measurements in the Canada Basin that typically range between 0.9 and 1.2 (Lachenbruch & Marshall, 1966; Ruppel et al, 2019). The average value for the 14 sites is also similar to estimated values of 1.1 W/m/K on the Beaufort Margin using indirect approaches (Phrampus et al, 2014).…”

“…Their 25 measurements, acquired using a 3.3-m probe deployed through a hole in drifting sea ice, produced nearly uniform heat flow values of ~60 mW/m 2 in the northern Canada Basin. Reanalysis of these data confirms background heat flow averaging ~55 mW/m 2 in the Central and Western Canada Basin (Ruppel et al, 2019). Since the Lachenbruch and Mashall studies of the 1960s, only a handful of additional heat flow studies have been conducted in the Canada Basin, with most in shallow water along the Canadian continental margin or Russian waters (e.g., Jones et al, 1989;Riedel et al, 2015;O'Regan et al, 2016).…”

“…Heat flow values associated with 195-80-Ma oceanic crust typically have an average value of 50 mW/m 2 (Sclater et al, 1980;Stein & Stein, 1992). Previous deep water (>3,000 mbsl) heat flow measurements in the Canada Basin are consistent with these predictions, averaging ~55 mW/m 2 (Lachenbruch & Marshall, 1966;Ruppel et al, 2019) and support a Mesozoic onset of rifting. However, ambiguity in the age and orientation of magnetic anomalies in the Canada Basin (e.g., Lane , 1997;McAdoo et al, 2008;Gaina et al, 2011) add uncertainty to the "windshield wiper" model.…”

“…For example, anomalously low shallow thermal gradients would support the hypothesis of sustained (decadal‐scale) ocean bottom warming and potentially widespread methane hydrate dissociation along the Beaufort Margin. Alternatively, thermal gradient values consistent with regional measurements, (ranging from 50 to 60°C/km) (e.g., Deming et al, 1992; Lachenbruch & Marshall, 1966; Ruppel et al, 2019) would not support this hypothesis.…”

Heat Flow Distribution in the Chukchi Borderland and Surrounding Regions, Arctic Ocean

“…In the Arctic region, heat flow data also shed light on environmental change, such as gas hydrate stability (e.g., Biastoch et al, 2011) and deep-water temperature variability (Carmack et al, 2012). Partly due to sea ice and resulting measurement difficulties, heat flow data in the Arctic Ocean were relatively sparse until the publication of the T-3 Project data in 2019, which were acquired from a drifting ice floe from 1963-1973(Lachenbruch et al, 2019Ruppel et al, 2019). The heat flow data from the T-3 Project covers the Alpha Ridge, Mendeleev Ridge, and part of the Canada Basin; however, heat flow data from the CBL are still lacking (Figure 1).…”