Influence of a West Antarctic mantle plume on ice sheet basal conditions

Abstract

The possibility that a deep mantle plume manifests Pliocene and Quaternary volcanism and potential elevated heat flux in West Antarctica has been studied for more than 30 years. Recent seismic images support the plume hypothesis as the cause of Marie Byrd Land (MBL) volcanism and geophysical structure. Mantle plumes may more than double the geothermal heat flux above nominal continental values. A dearth of in situ ice sheet basal data exists that samples the heat flux. Consequently, we examine a realistic distribution of heat flux associated with a possible late Cenozoic mantle plume in West Antarctica and explore its impact on thermal and melt conditions at the ice sheet base. We use a simple analytical mantle plume parameterization to produce geothermal heat flux at the base of the ice sheet. The three‐dimensional ice flow model includes an enthalpy framework and full‐Stokes stress balance. As both the putative plume location and extent are uncertain, we perform broadly scoped experiments to characterize the impact of the plume on geothermal heat flux and ice sheet basal conditions. The experiments show that mantle plumes have an important local impact on the ice sheet, with basal melting rates reaching several centimeters per year directly above the hotspot. In order to be consistent with observations of basal hydrology in MBL, the upper bound on the plume‐derived geothermal heat flux is 150 mW/m2. In contrast, the active lake system of the lower part of Whillans Ice Stream suggests a widespread anomalous mantle heat flux, linked to a rift source.

The Crust and Upper Mantle Structure of Central and West Antarctica From Bayesian Inversion of Rayleigh Wave and Receiver Functions

“…Small amounts of partial melt, associated with the MBL volcanic systems, may also contribute to the seismic anomaly. The seismic signature is consistent with other studies suggesting a weak mantle plume, causing the MBL thermal anomalies and volcanism (e.g., Accardo et al, ; Seroussi et al, ), in that the velocity anomalies near the center of the dome are stronger and extend deeper than surrounding areas. At greater depth (>200 km), body wave tomography (i.e., Emry et al, ; Hansen et al, ) provides better images of this region, which suggests the presence of a possibly secondary plume structure.…”

Heat Flow in Southern Australia and Connections With East Antarctica

“…In contrast, there is no evidence from the An model that there are any regions of high Antarctic heat flow corresponding to the elevated values of northern India, yet the Martos model shows a circular feature of high heat flow at this location. Elevated heat flow at the southern edge of George V Land is imaged in all geophysical models and is a result of the West Antarctic Rift System, driven by recent magmatism and the likely presence of a magmatic plume (Ivins et al, ; Seroussi, Ivins et al, ).…”

Spatially Variable Geothermal Heat Flux in West Antarctica: Evidence and Implications

“…Zones of elevated GHF below the WAIS can produce considerable volumes of subglacial meltwater (Vogel & Tulaczyk, ) and may contribute to the development and dynamics of subglacial lakes, the advection of organic and inorganic compounds into subglacial habitats, and thus the presence and metabolism of microbial biomes (Christner et al, ; Jørgensen & Boetius, ). Seroussi et al () found that locally high GHF (≥150 mW m −2 ) below the Whillans Ice Stream was needed to reproduce the observed subglacial lakes in an ice sheet model. As the ice sheet thins, increasing the vertical conductive heat flux, GHF variability may be more important to predictions of the basal thermal regime, particularly the development of basal frozen zones such as ice rises that might stabilize ice retreat (Favier & Pattyn, ; Rignot et al, ).…”