A decade of the heat-pipe Earth hypothesis
Authors: Webb A Alexander G , Moore William B , Zuo Jiawei , Müller Thomas , Tang Chun'an , Simon Justin I , Haproff Peter J , Leung Chit Yan Eunice , Ganbat Ariuntsetseg , Ramírez-Salazar Anthony , Piazolo Sandra , Wang Qin , Sorger Dominik , Chin Emily J , Johnson Tim E , McKenzie N Ryan , Kirkland Christopher L , Cheng H C Jupiter , Hauzenberger Christoph 
Published: March 2024

In his classic contribution &#8220;A Heat Pipe Mechanism for Volcanism and Tectonics on Venus&#8221; [1989, JGR 94, B3, 2779-2785], Turcotte applied O&#8217;Reilly and Davies&#8217; [1981, GRL 8, 313-316] model for Io&#8217;s volcanic heat transport to Venus, and further speculated that this mechanism might explain a thick lithosphere inferred for Archean Earth. The latter idea &#8211; to consider heat-pipe cooling for Earth &#8211; then lay fallow until roughly 15 years ago, when one of us (Moore) argued in talks and manuscripts (all rejected) that the cold, thick, and strong lithosphere generated by heat-pipe cooling might offer an alternative to subduction tectonics for generating the &#8220;too-cold&#8221; Hadean zircons reported by Hopkins et al. [2008, Nature 456, 493-496]. With the additional realization that the heat-pipe cooling mechanism might similarly account for the rocks preserved from the first half of Archean time, the concept of an early heat-pipe Earth finally received broad consideration just over a decade ago [Moore &amp; Webb, 2013 Nature 501, 501-505].&#160;Heat-pipe cooling is a hot stagnant-lid cooling mode based on our understanding of the active volcano-tectonics of Jupiter&#8217;s moon Io [O&#8217;Reilly &amp; Davies, 1981]. Heat-pipes are not plumes: heat-pipes are conduits channeling melts upwards through lithosphere, whereas plumes commonly span the whole crust and mantle and accordingly have relatively complex histories. The heat-pipe Earth hypothesis posits that during the first third of Earth history, rapid volcanism dominated cooling from the end of the magma ocean period to the onset of (episodic?) plate tectonics. During the heat-pipe period, voluminous mafic volcanism resulted in protracted resurfacing, causing quasi-continuous burial of cold, hydrated surface materials that (1) cooled a single-plate lithosphere and (2) generated tonalite-trondhjemite-granodiorite melts deep in the lithosphere. It is noteworthy that the burial of surface materials to mantle depths &#8211; long seen as a distinguishing characteristic of plate tectonics &#8211; is a hallmark of heat-pipe cooling. &#160;&#160;The past decade has seen abundant explorations and tests of the heat-pipe Earth hypothesis, as well as renewed interest in the heat-pipe cooling mechanism for other terrestrial bodies. This presentation will review major results and consider key critiques. Highlights include demonstrations that heat-pipe cooling viably explains: (a) the early histories of the lithospheres preserved at Mercury, Venus, Mars, and the Moon, and thus can be hypothesized as a universal cooling mechanism for early / hot terrestrial bodies in our Solar System and others [Moore et al., 2017 EPSL 474, 13-19; Peterson et al., 2021 Sci.Adv. 7:eabh2482]; (b) the Eoarchean development of the Isua supracrustal belt of southern West Greenland [Webb et al., 2020 Lithosphere 12, 166-179 and a collection of subsequent works], which was previously understood exclusively via plate tectonic models; (c) the initiation of a global plate network, as thinning and corresponding warming of lithosphere during waning heat-pipe cooling caused thermal expansion which overcame the tensional strength of the lithosphere [Tang et al., 2020 Nat.Comm. 11:3621]; and (d) Earth&#8217;s detrital zircon depositional records older than ~3.3 Ga [Zuo et al., 2021 EPSL 575:117182]. &#160;