Continental lithospheric temperatures: A review

Abstract

Thermal structure of the lithosphere exerts a primary control on its strength and density and thereby its dynamic evolution as the outer thermal and mechanic boundary layer of the convecting mantle. This contribution focuses on continental lithosphere. We review constraints on thermal conductivity and heat production, geophysical and geochemical/petrological constraints on thermal structure of the continental lithosphere, as well as steady-state and non-steady state 1D thermal models and their applicability. Commonly used geotherm families that assume that crustal heat production contributes an approximately constant fraction of 25-40% to surface heat flow reproduce the global spread of temperatures and thermal thicknesses of the lithosphere below continents. However, we find that global variations in seismic thickness of continental lithosphere and seismically estimated variations in Moho temperature below the US are more compatible with models where upper crustal heat production is 2-3 times higher than lower crustal heat production (consistent with rock estimates) and the contribution of effective crustal heat production to thermal structure (i.e. estimated by describing thermal structure with steady-state geotherms) varies systematically from 40-60% in tectonically stable low surface heat flow regions to 20% or lower in higher heat flow tectonically active regions. The low effective heat production in tectonically active regions is likely partly the expression of a non-steady thermal state and advective heat transport.

Geophysical and Geochemical Constraints on Neogene‐Recent Volcanism in the North American Cordillera

“…Also, there may be an effect of the different H 2 O content and the change from spinel to garnet phases, giving a difference in the velocity‐temperature relation across the LAB. Although there have been recent improvements, there are still absolute temperature uncertainties of at least ±50°C (e.g., Goes, Govers, & Vacher, 2000; Goes, Hasterok, et al., 2020; Jackson & Faul, 2010; McCarthy et al., 2011; Porter et al., 2019). Most recent estimates of temperature from tomography velocities indicate 1,300°C–1,400°C at 60–70 km where partial melt is not inferred (e.g., Goes, Hasterok, et al., 2020; Goes & van der Lee, 2002; Hansen et al., 2015; Klocking et al., 2018) (Figures 7 and 8), which agrees with the common Cordillera upper asthenosphere mantle solidus at 60–70 km from studies of volcanic geochemistry.…”

Lithosphere Mantle Density of the North China Craton

“…The choice of heat production values in the crust, in particular in sediments and upper crust, also has strong effect on the thermal model (Artemieva & Mooney, 2001; Goes et al, 2020). This information is largely unavailable for the NCC.…”

“…However, such studies remain very sparse in the NCC. In the absence of a regional-scale database, we follow a commonly adopted strategy (Artemieva & Mooney, 2001;Balling, 1995;Furlong & Chapman, 2013;Goes et al, 2020;Jaupart & Mareschal, 1999;Mareschal, 1991). For each crustal layer (their thickness is constrained by a high-resolution regional crustal model NCcrust; Xia et al, 2017) and the LM, we adopt standard values of heat production (Artemieva & Mooney, 2001;Ashwal et al, 1987;Balling, 1995;Fountain et al, 1987;Gard et al, 2019;Jaupart & Mareschal, 1999;Pinet & Jaupart, 1987;Rudnick et al, 1998) and thermal conductivity (Cermak & Rybach, 1982;Clauser & Huenges, 2013;G.-Z.…”

Hygrometric Control on the Lithosphere‐Asthenosphere Boundary: A 28 Million Year Record From the Canadian Cordillera

“…The factors that control the depth and structure of the LAB remain unclear, as are the time and process of lithosphere thinning surmised to have occurred in the back arc of this and many other convergent continental margins (Currie & Hyndman, 2006;Wang & Currie, 2015).Subduction for the past ∼50 Myr beneath the Canadian Cordillera (CC) has been cut off by the Queen Charlotte fault zone (Figure 1), but recently enough that high back arc temperatures have not decreased significantly. The inception and longevity of a hot thin mantle lithosphere beneath this and other convergent continental margins bears on the dynamics of mobile belts (Goes et al, 2019;Hyndman, 2019). One view has thin upper crust decoupled from weak lower crust and lithospheric mantle, propagating stress far in-board from the active convergent margin (Hyndman, 2017) whereas other models have a distribution of stress throughout the whole lithosphere (Finzel et al, 2014).…”