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A new volcanic province: An inventory of subglacial volcanoes in West Antarctica

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The West Antarctic Ice Sheet overlies the West Antarctic Rift System about which, due to the comprehensive ice cover, we have only limited and sporadic knowledge of volcanic activity and its extent. Improving our understanding of subglacial volcanic activity across the province is important both for helping to constrain how volcanism and rifting may have influenced ice-sheet growth and decay over previous glacial cycles, and in light of concerns over whether enhanced geothermal heat fluxes and subglacial melting may contribute to instability of the West Antarctic Ice Sheet. Here, we use ice-sheet bed-elevation data to locate individual conical edifices protruding upwards into the ice across West Antarctica, and we propose that these edifices represent subglacial volcanoes.We used aeromagnetic, aerogravity, satellite imagery and databases of confirmed volcanoes to support this interpretation. The overall result presented here constitutes a first inventory of West Antarctica's subglacial volcanism. We identified 138 volcanoes, 91 of which have not previously been identified, and which are widely distributed throughout the deep basins of West Antarctica, but are especially concentrated and orientated along the > 3000 km central axis of the West Antarctic Rift System.
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A new volcanic province: an inventory of subglacial
volcanoes in West Antarctica
MAXIMILLIAN VAN WYK DE VRIES*, ROBERT G. BINGHAM & ANDREW S. HEIN
School of GeoSciences, University of Edinburgh, Drummond Street, Edinburgh EH8 9XP, UK
*Correspondence: gmaxvwdv@gmail.com
Abstract: The West Antarctic Ice Sheet overlies the West Antarctic Rift System about which, due
to the comprehensive ice cover, we have only limited and sporadic knowledge of volcanic activity
and its extent. Improving our understanding of subglacial volcanic activity across the province is
important both for helping to constrain how volcanism and rifting may have inuenced ice-sheet
growth and decay over previous glacial cycles, and in light of concerns over whether enhanced geo-
thermal heat uxes and subglacial melting may contribute to instability of the West Antarctic Ice
Sheet. Here, we use ice-sheet bed-elevation data to locate individual conical edices protruding
upwards into the ice across West Antarctica, and we propose that these edices represent subglacial
volcanoes. We used aeromagnetic, aerogravity, satellite imagery and databases of conrmed volca-
noes to support this interpretation. The overall result presented here constitutes a rst inventory of
West Antarcticas subglacial volcanism. We identied 138 volcanoes, 91 of which have not previ-
ously been identied, and which are widely distributed throughout the deep basins of West Antarc-
tica, but are especially concentrated and orientated along the >3000 km central axis of the West
Antarctic Rift System.
Gold Open Access: This article is published under the terms of the CC-BY 3.0 license.
West Antarctica hosts one of the most extensive
regions of stretched continental crust on the Earth,
comparable in dimensions and setting to the East
African Rift System and the western USAs Basin
and Range Province (Fig. 1) (e.g. see Behrendt
et al. 1991; Dalziel 2006; Kalberg et al. 2015). Im-
proved knowledge of the regions geological struc-
ture is important because it provides the template
over which the West Antarctic Ice Sheet (WAIS)
has waxed and waned over multiple glaciations
(Naish et al. 2009; Pollard & DeConto 2009; Jamie-
son et al. 2010), and this provides a rst-order
control on the spatial conguration of the WAIS
ice dynamics (Studinger et al. 2001; Jordan et al.
2010, Bingham et al. 2012). The subglacial region
today is characterized by an extensive and complex
network of rifts, which is likely to have initiated at
various times since the Cenozoic (Fitzgerald 2002;
Dalziel 2006; Siddoway 2008; Spiegel et al. 2016),
and which in some locations may still be active (Beh-
rendt, et al. 1998; LeMasurier 2008; Lough et al.
2013; Schroeder et al. 2014). Collectively, this series
of rifts beneath the WAIS has been termed the West
Antarctic Rift System (WARS), and is bounded by
the Transantarctic Mountains to the south (Fig. 1).
In other major rift systems of the world, rift
interiors with thin, stretched crust are associated
with considerable volcanism (e.g. Siebert & Simkin
2002). However, in West Antarctica, only a few
studies have identied subglacial volcanoes and/or
volcanic activity (e.g. Blankenship et al. 1993;
Behrendt et al. 1998, 2002; Corr & Vaughan 2008;
Lough et al. 2013), with the ice cover having deterred
a comprehensive identication of the full spread
of volcanoes throughout the WARS. Improving on
this limited impression of the WARSdistribution
of volcanism is important for several reasons. Firstly,
characterizing the geographical spread of volcanic
activity across the WARS can complement wider
efforts to understand the main controls on rift vol-
canism throughout the globe (Ellis & King 1991;
Ebinger et al. 2010). Secondly, volcanic edices,
by forming protuberancesat the subglacial inter-
face, contribute towards the macroscale roughness
of ice-sheet beds, which in turn forms a rst-order
inuence on ice ow (cf. Bingham & Siegert 2009).
Thirdly, volcanism affects geothermal heat ow
and, hence, basal melting, potentially also impacting
upon ice dynamics (Blankenship et al. 1993; Vogel
et al. 2006). Fourthly, it has been argued that sub-
glacial volcanic sequences can be used to recover
palaeoenvironmental information from Quaternary
glaciations, such as palaeo-ice thickness and thermal
regime (e.g. Smellie 2008; Smellie & Edwards 2016).
In this contribution, we present a new regional-
scale assessment of the likely locations of volca-
noes in West Antarctica based on a morphometric
(or shape) analysis of West Antarcticas ice-bed
topography. Volcano shape depends on three prin-
cipal factors: (1) the composition of the magma
From:SIEGERT, M. J., JAMIESON,S.S.R.&WHITE, D. A. (eds) Exploration of Subsurface Antarctica: Uncovering
Past Changes and Modern Processes. Geological Society, London, Special Publications, 461,
https://doi.org/10.1144/SP461.7
© 2017 The Author(s). Published by The Geological Society of London.
Publishing disclaimer: www.geolsoc.org.uk/pub_ethics
erupted; (2) the environment into which the magma
has been erupted; and (3) the erosional regime to
which the volcano has been subjected since eruption
(Hickson 2000; Grosse et al. 2014; Pedersen &
Grosse 2014). Magma composition in large conti-
nental rifts generally has lowmedium silica content
with some more alkaline eruptions (Ebinger et al.
2013). In West Antarctica, where most knowledge
of volcanoes is derived from subaerial outcrops in
Marie Byrd Land, volcanoes are composed of inter-
mediate alkaline lavas erupted onto a basaltic shield,
with smaller instances being composed entirely of
basalt and a few more evolved compositions (tra-
chyte, rhyolite: LeMasurier et al. 1990; LeMasurier
2013). We therefore consider it likely that many
structures in the WARS are also basaltic. Regard-
ing the environment of eruption, subaerial basaltic
eruptions typically produce broad shield-type cones
protruding upwards from the surrounding landscape
(Grosse et al. 2014). Under subglacial conditions,
monogenetic volcanoes often form steeper-sided,
at-topped structures made up of phreatomagmatic
deposits draped on pillow lava cores and overlain
by lava-fed deltas known as tuyas (Hickson 2000;
Pedersen & Grosse 2014; Smellie & Edwards
2016). Larger, polygenetic volcanic structures give
rise to a range of morphometries reecting the mul-
tiple events that cause their formation, but many
also have overall conicalstructures similar to stra-
tovolcanoes or shield volcanoes (Grosse et al. 2014;
Smellie & Edwards 2016).
In the WARS, the macrogeomorphology is
dominated by elongate landforms resulting from
geological rifting and subglacial erosion. We
Fig. 1. (a) Location of the main components of the West Antarctic Rift System and conrmed volcanoes (red circles:
after LeMasurier et al. 1990; Smellie & Edwards 2016). (b) Location of Holocene volcanoes (red circles) in the
Ethiopia/Kenya branch of the East African Rift (red shaded area). The majority of this activity is aligned along the
rift axis with occasional ank volcanism. Data from Siebert & Simkin (2002) and Global Volcanism Program (2013).
M. VAN WYK DE VRIES ET AL.
propose here that, in this setting, the most reasonable
explanation for any conesbeing present is that they
must be volcanic in origin. We dene conesas any
features that have a low length/width ratio viewed
from above; hence, for this study, we include cones
even with very low slope angles. Thus, we use
cones in this subglacial landscape as diagnostic of
the presence of volcanoes. We note that identifying
cones alone will by no means identify all volcanism
in the WARS. For example, volcanic ssures erup-
tions, a likely feature of rift volcanism, will yield
ridge forms, or tindars(Smellie & Edwards 2016),
rather than cones. Moreover, in the wet basal envi-
ronment of the WAIS, the older the cone the more
likely it will have lost its conical form from sub-
glacial erosion. Therefore, cones present today are
likely to be relatively young although we cannot
use our method to distinguish whether or not the
features are volcanically active.
Methods
Our underpinning methodology was to identify
cones that protrude upwards from a digital elevation
model (DEM) of Antarcticas subglacial topography,
and to assess the likelihood that each cone is a vol-
canic edice. We undertook our analysis on the
Bedmap2 DEM (Fretwell et al. 2013) domain
encompassed by the WARS, which incorporates all
of West Antarctica, the Ross Ice Shelf and the Trans-
antarctic Mountains fringing East Antarctica that
ank the WARS (Elliott 2013). Importantly, while
Bedmap2 represents the state-of-the-art knowledge
of West Antarcticas subglacial landscape, it is
derived from variable data coverage, the vast major-
ity of the data being sourced from airborne radar-
sounding acquired along one-dimensional tracks.
Along the radar tracks the horizontal spacing of
bed-elevation data points can reach a few metres,
but between tracks the spacing is often several kilo-
metres. The DEM itself is presented as a 1 km
gridded product, although the raw data were initially
gridded at 5 km (Fretwell et al. 2013). Therefore,
while the DEM cannot capture the ne-scale topog-
raphy now routinely acquired by satellite and air-
borne altimetry, and which has been exploited for
multiple morphometric analyses (e.g. Pedersen &
Grosse 2014; Lindback & Pettersson 2015; Ely
et al. 2016), it nevertheless presents a workable start-
ing point for identifying volcanic edices. We con-
sider how some of the DEMs limitations can be
overcome in our analysis below.
We dened a cone as an upwards protuberance
from the DEM whose elongation ratio (width
v. length) <1.5. Over the domain, but excluding non-
grounded ice (primarily the Ross Ice Shelf) where
the subglacial topography is poorly characterized,
we rst extracted cones protruding at least 100 m
from the surrounding terrain. The bed-elevation un-
certainties within the DEM prevent reliable identi-
cation of smaller edices. Elevation proles across
each cone were then extracted from Bedmap2 at
multiple angles with respect to the current ice-ow
direction (taken from Rignot et al. 2011). Where
radar proles directly traversed a cone, we further
cross-checked the shape of the bed directly from
the raw data. This is part of our procedure for
accounting for any artefacts in Bedmap2, which
involves corroborating our identied volcanoes
with auxiliary datasets. To assess the likelihood
that the Bedmap2-extracted cones were (a) not
merely interpolation-induced artefacts and (b) likely
represent volcanoes, we implemented a scheme
wherein points were awarded where auxiliary data
ground-truthed the bed DEM and/or gave greater
condence in a volcanic interpretation. The assess-
ment criteria are as follows, with points awarded
for each and data-source references given in Table 1:
(1) Whether a cone is found within 5 km of the
nearest raw ice-thickness data.
(2) Whether a cone is overlain by an upwards-
protruding prominence in the surface of the
ice draped over it. This criterion takes advan-
tage of the fact that, under the right balance
between ice thickness and ice-ow speed, sub-
glacial topographical prominences can be
expressed at the ice surface (e.g. De Rydt
et al. 2013).
(3) Whether a cone is discernible as a feature at the
ice surface in visible satellite imagery. Various
recent studies have demonstrated that subgla-
cial features can be outlined by visible expres-
sions in surface imagery (e.g. Ross et al. 2014;
Chang et al. 2015; Jamieson et al. 2016).
(4) Whether a cone is associated with a clear con-
centric magnetic anomaly. This depends on
the potential volcano having a pillow-lava
core, rather than being composed solely of
tuff. This is consistent with the thickness
of ice overlying the cones and the erodibility
of tuff/tephra deposits. Strong geomagnetic
anomalies have long been suggested as evi-
dence of subglacial volcanism in the WARS
(e.g. Behrendt et al. 1998, 2002).
(5) Whether a cone is associated with a concentric
free-air and/or Bouguer anomaly.
Each cone was assigned a nal condence factor
value of between 0 and 5 by summing up the points
from the ve indicators described above (Table 1).
Results
Our morphometric analysis of subglacial West Ant-
arctica recovers a total of 178 conical structures
SUBGLACIAL VOLCANOES IN WEST ANTARCTICA
Table 1. Classication scheme used in assessing condence that a cone extracted from Bedmap2 (Fretwell et al. 2013) can be interpreted as a volcano
Condence assessment criterion Dataset/source Condence score
0 0.5 1
(1) Distance to nearest raw ice-thickness
measurement Figure 3 in Fretwell et al. (2013) >15 km 515 km <5 km
(2) Expression in ice-surface DEM overlying
identied subglacial cone Bedmap2 ice-surface DEM: Fretwell
et al. (2013) No expression Associated but off-
centre anomaly Direct overlying
anomaly
(3) Expression in MODIS imagery of the ice
surface overlying the identied
subglacial cone
MODIS Mosaic of Antarctica:
Scambos et al. (2007) No expression Weak expression Clear expression
(4) Magnetic anomaly data ADMAP: Kim et al. (2007) No anomaly Weak anomaly Clear anomaly
(5) Gravity anomaly data Studinger et al. (2002); Damiani et al.
(2014); Scheinert et al. (2016) No anomaly Weak anomaly Clear anomaly
Full scores are given in Table 2.
M. VAN WYK DE VRIES ET AL.
located beneath the grounded WAIS and along the
WARS (Fig. 2; Table 2). Of these, 80% are located
within 15 km of the raw ice-thickness data measure-
ments (Fretwell et al. 2013) and 30% are identied
from the DEM at sites where volcanoes, either active
or inactive, have previously been identied (LeMa-
surier et al. 1990; LeMasurier 2013; Wardell et al.
2014). Many cones were crossed directly by radio-
echo-sounding ightlines, allowing verication of
their proles (e.g. Fig. 3) thus, while there is, inev-
itably, some smoothing in the Bedmap2 interpola-
tion, the major features of interest are largely
captured. One of our condence tests for volcanic
interpretation of cones also takes into account prox-
imity to the raw ice-thickness measurements, further
discounting DEM interpolation as a disproportionate
inuence on the results.
The identied cones range in height between 100
and 3850 m, with an average relief of 621 m, includ-
ing 29 structures >1 km tall that are mainly situated
in Marie Byrd Land and the central rift zone. The
basal diameter of the cones ranges between 4.5 and
58.5 km, with an average diameter of 21.3 km.
Most of the cones have good basal symmetry, with
63% of the long to short axis ratios being <1.2.
Table 3 presents a more in-depth statistical analysis
of the morphology of these features and compares
them to a global volcanic database (Grosse et al.
2014). Figure 4 shows 1:1 cross-sections of three
of the newly identied cones along with three prom-
inent shield volcanoes for comparison.
Seventy-eight per cent of the cones achieve a
condence score (from our ve-point scheme) >3,
and we therefore consider it reasonable to interpret
these 138 cones henceforth as subglacial volcanoes.
(We note that 98% of the 47 previously identied
volcanoes in West Antarctica (visible at the surface
and listed by LeMasurier et al. 1990) achieved a con-
dence score >3.) The volcanoes are distributed
across subglacial West Antarctica, but are especially
concentrated in Marie Byrd Land (one cone per 11
200 ± 600 km
2
); and along a central belt roughly
corresponding to the rifts central sinuous ridge
(Behrendt et al. 1998), with one cone per 7800 ±
400 km
2
. For comparison, the overall volcanic edi-
ce concentration along the East African Rift is
roughly one volcano per 7200 km
2
, rising to one vol-
cano per 2000 km
2
in the densest regions (Global
Volcanism Program 2013).
Discussion
Morphometry as a tool for identifying
subglacial volcanoes
We consider here three main implications that
arise from our ndings. Firstly, our approach
demonstrates that it is possible to use morphometry
on Antarcticas subglacial DEM, crucially together
with relevant auxiliary information, to identify
potential subglacial volcanic edices beneath West
Antarctica. Secondly, it highlights that subglacial
West Antarctica and, in essence, the WARS
comprises one of the worlds largest volcanic prov-
inces (cf. LeMasurier et al. 1990; Smellie & Edwards
2016), and it provides basic metrics concerning the
locations and dimensions of the main volcanic
zones. Thirdly, it serves to highlight the wide spread
of subglacial volcanism beneath the WAIS, which
may impact upon its response to external forcing
through affecting coupling of the ice to its bed, and
may have implications for future volcanic activity
as ice cover thins.
To our knowledge, our study here is the rst to
use morphometry to identify volcanic edices on
the continental scale beneath Antarctica. The extent
of this volcanism has only previously been inferred
from geophysical studies (Behrendt et al. 2002).
Morphometry has been used widely elsewhere in
volcanology: for example, to catalogue volcanic
parameters, such as height, base width and crater
width (e.g. McKnight & Williams 1997; Pedersen
& Grosse 2014), or to reconstruct eroded volcanic
edices (Favalli et al. 2014). It has been applied to
resolve volcanic characteristics in subaerial, subma-
rine (e.g. Stretch et al. 2006) and extraterrestrial (e.g.
Broz et al. 2015) settings. However, in all such cases
volcanic morphometry has been applied to DEMs
assembled from evenly distributed elevation mea-
surements derived from sensors viewing unobscured
surfaces. For subglacial Antarctica, having con-
dence that the subglacial DEM that has been con-
structed from non-random elevation measurements
has sufcient resolution for the applied interpretation
is key. Recent years have witnessed increasing glaci-
ological recovery of subglacial information from
morphometry. For example, seeding centres for gla-
ciation of the WAIS (Ross et al. 2014) and the East
Antarctic Ice Sheet (Bo et al. 2009; Rose et al. 2013)
have been identied by the preponderance of sharp
peaks, cirque-like features and closely spaced val-
leys relative to other parts of the subglacial land-
scape. Elsewhere, landscapes of selective linear
erosion, diagnostic of former dynamism in now-
stable regions of ice, have been detected from the
presence of signicant linear incisions (troughs)
into otherwise at higher surfaces (plateaux)
(Young et al. 2011; Jamieson et al. 2014; Rose
et al. 2014). All of these studies have in common
that they have closely considered auxiliary evidence
to the morphometry and, hence, have not relied on
the surface shape alone in coming to interpretations
concerning landscape formation. We have shown
here that such a combined approach is also valid
for locating and mapping numerous previously
SUBGLACIAL VOLCANOES IN WEST ANTARCTICA
Fig. 2. Location map of conical edices (circles) identied from Bedmap2 (greyscale background) across the West Antarctic Rift System. The data are tabulated in Table 2. The
circle colour represents the condence factor used to assess the likelihood of cones being subglacial volcanoes, and the circle size is proportional to the cones basal diameter.
Circles with black rims represent volcanoes that have been conrmed in other studies (LeMasurier et al. 1990; Smellie & Edwards 2016), generally those that have tips which
protrude above the ice surface.
M. VAN WYK DE VRIES ET AL.
Table 2. Tabulation of subglacial cone coordinates, dimensions and volcanic-interpretation condence factors (see Table 1)
Number Height
(m) Average
diameter
(km)
Elongation
ratio Volume
(km
3
)Latitude Longitude Volcano condence factor Previously
identied
12345Sum
1 800 26 1.08 106 74.00 80.38 0.5 1 1 0.5 0.5 3.5 Yes
2 600 14 1.15 23 75.60 81.60 1 1 0 1 0.5 3.5 No
3 300 7.5 1.14 3 76.13 83.53 1 0.5 0 1 0.5 3 No
4 300 18.5 1.18 20 76.80 85.27 1 0 0 1 0.5 2.5 No
5 650 24.5 1.04 77 74.47 86.40 0.5 0.5 0.5 0.5 0.5 2.5 No
6 350 17.5 1.19 21 76.74 87.50 1 0 0.5 1 0.5 3 No
7 250 17 1.27 14 76.97 87.89 1 0 0 1 0.5 2.5 No
8 950 29 1.07 157 77.37 88.10 1 0 1 0.5 0.5 3 No
9 300 19.5 1.05 22 77.40 89.38 1 0.5 1 0.5 0.5 3.5 No
10 350 15.5 1.07 17 77.32 90.34 1 0.5 1 0.5 0.5 3.5 No
11 600 32.5 1.17 124 74.27 89.58 0.5 0.5 0 0.5 0.5 2 No
12 550 36 1.06 140 74.07 91.18 0.5 0 1 0.5 0.5 2.5 No
13 450 27.5 1.20 67 72.90 91.30 0 1 0.5 0.5 0.5 2.5 No
14 500 22.5 1.25 50 74.05 92.90 1 1 0.5 1 0.5 4 No
15 1400 22.5 1.25 139 73.73 93.68 0.5 1 1 1 0.5 4 Yes
16 1450 19.5 1.29 108 70.03 125.97 1 1 1 1 0.5 4.5 Yes
17 1300 27 1.25 186 73.89 94.64 0.5 1 1 1 0.5 4 Yes
18 400 20 1.11 31 78.03 92.95 1 1 0 0.5 0.5 3 No
19 325 18.5 1.18 22 78.21 93.20 1 1 0 0.5 0.5 3 No
20 200 9.5 1.11 4 78.20 93.82 1 0.5 0 0.5 0.5 2.5 No
21 600 20.5 1.16 49 78.15 94.62 1 1 0 0.5 0.5 3 No
22 375 18.5 1.06 25 78.68 95.65 1 0 0.5 0.5 0.5 2.5 No
23 250 19 1.11 18 78.52 96.16 1 0.5 1 1 0.5 4 No
24 700 26.5 1.30 96 78.13 96.36 1 0.5 0 0.5 0.5 2.5 No
25 450 22.5 1.25 45 78.00 97.16 1 1 0 0.5 0.5 3 No
26 250 13.5 1.25 9 78.67 97.68 1 1 0 1 1 4 No
27 500 24.5 1.13 59 74.97 96.54 0.5 1 1 1 0.5 4 No
28 400 16.5 1.36 21 74.86 97.42 1 1 0 1 0.5 3.5 No
29 550 16 1.13 28 75.07 99.54 1 1 1 1 0.5 4.5 Yes
30 820 20.5 1.16 68 74.73 99.04 1 1 1 1 0.5 4.5 Yes
31 650 29 1.15 107 75.07 99.54 0.5 1 1 1 0.5 4 Yes
32 750 31 1.07 141 74.03 98.83 0.5 0 0 1 0.5 2 No
33 950 26 1.17 126 74.21 100.19 1 1 1 0.5 0.5 4 No
34 900 30 1.14 159 74.51 99.94 1 0 1 0.5 0.5 3 Yes
(Continued)
SUBGLACIAL VOLCANOES IN WEST ANTARCTICA
Table 2. Tabulation of subglacial cone coordinates, dimensions and volcanic-interpretation condence factors (see Table 1) (Continued )
Number Height
(m) Average
diameter
(km)
Elongation
ratio Volume
(km
3
)Latitude Longitude Volcano condence factor Previously
identied
12345Sum
35 300 15.5 1.21 14 74.72 100.09 1 0 1 0.5 0.5 3 No
36 325 11.5 1.30 8 75.24 96.95 1 1 1 0.5 0.5 4 No
37 500 34 1.13 113 72.19 97.70 0 1 1 1 0.5 3.5 Yes
38 1025 40.5 1.19 330 72.54 97.61 0 0 0.5 1 0.5 2 Yes
39 400 20.5 1.16 33 72.51 98.38 0 1 1 1 0.5 3.5 Yes
40 525 28 1.15 81 72.42 99.23 0.5 1 1 1 0.5 4 Yes
41 325 20.5 1.16 27 72.47 99.94 0 1 1 1 0.5 3.5 Yes
42 550 33.5 1.16 121 72.32 101.07 0.5 1 1 0.5 0.5 3.5 Yes
43 225 11.5 1.30 6 73.87 103.30 0 0.5 1 1 0.5 3 No
44 675 26.5 1.12 93 75.45 103.29 1 1 1 0.5 1 4.5 No
45 350 9.5 1.38 6 78.41 101.96 1 0 0 0.5 0.5 2 No
46 575 23 1.19 60 79.65 101.80 1 0.5 0 1 0.5 3 No
47 275 12 1.18 8 80.03 101.60 1 0.5 0 0.5 0 2 No
48 250 13 1.17 8 80.15 101.46 1 0.5 0 0.5 0 2 No
49 175 21.5 1.15 16 80.17 103.39 0.5 0.5 0.5 0.5 2 No
50 325 22 1.20 31 78.87 102.91 1 0.5 0.5 0.5 0 2.5 No
51 225 27 1.16 32 80.40 105.61 0.5 1 0 1 0.5 3 No
52 1175 23 1.19 122 78.74 104.24 1 1 1 0.5 1 4.5 No
53 125 15 1.14 6 77.61 103.56 1 0.5 0.5 0.5 1 3.5 No
54 225 11.5 1.30 6 82.05 111.42 1 0.5 1 1 0.5 4 No
55 175 23 1.19 18 77.43 105.77 1 1 1 1 0.5 4.5 No
56 150 9 1.25 2 77.70 74.55 1 0.5 0 0.5 0 2 No
57 275 13.5 1.25 10 78.46 107.77 1 0.5 1 0.5 0 3 No
58 175 11 1.44 4 76.72 106.61 1 1 1 1 0.5 4.5 No
59 150 12.5 1.27 5 76.87 106.38 1 1 1 1 1 5 No
60 1200 33.5 1.16 264 79.15 111.05 1 0 1 1 1 4 No
61 450 14.5 1.23 19 79.60 111.45 1 0 0 1 0.5 2.5 No
62 200 6 1.40 1 80.42 114.00 1 0.5 0 1 0 2.5 No
63 425 10 1.22 8 75.22 106.92 0 0.5 0.5 0.5 0.5 2 No
64 450 18 1.12 29 75.71 108.40 1 0 1 0.5 1 3.5 No
65 375 14.5 1.23 15 76.11 107.68 1 0 1 0.5 1 3.5 No
66 400 17 1.27 23 76.38 109.78 1 0.5 1 1 1 4.5 No
67 325 10.5 1.33 7 74.60 110.62 0.5 1 1 0.5 0.5 3.5 No
68 400 19 1.24 28 74.81 110.57 1 1 1 0.5 0.5 4 No
69 350 14 1.33 13 75.00 110.43 0.5 1 1 0.5 0.5 3.5 No
70 750 30 1.14 132 74.89 111.26 1 1 1 0.5 0.5 4 No
71 2300 51.5 1.15 1197 75.60 110.70 1 1 1 0.5 1 4.5 Yes
M. VAN WYK DE VRIES ET AL.
72 3200 58.5 1.13 2149 76.52 112.02 1 1 1 1 1 5 Yes
73 250 15.5 1.07 12 77.21 111.92 1 0 0.5 0.5 1 3 No
74 1025 36 1.00 261 77.72 112.64 1 0.5 1 1 0.5 4 No
75 300 16 1.13 15 77.67 114.04 1 0.5 1 0.5 1 4 No
76 625 26 1.17 83 77.80 115.00 1 1 1 0.5 1 4.5 No
77 650 12 1.18 18 78.08 115.37 1 0 0.5 0.5 0 2 No
78 400 10.5 1.33 9 78.11 115.93 1 1 0.5 0.5 0 3 No
79 350 13.5 1.25 13 78.93 115.69 1 0 0.5 1 1 3.5 No
80 325 20.5 1.28 27 79.68 113.53 1 1 0 1 1 4 No
81 200 6 1.40 1 80.38 115.11 1 0.5 0 1 1 3.5 No
82 125 4.5 1.25 0 80.38 115.11 1 0.5 0 1 1 3.5 No
83 150 10 1.22 3 80.34 116.40 1 1 0 1 1 4 No
84 1750 31.5 1.10 341 80.30 117.49 1 1 1 1 1 5 No
85 800 20 1.22 63 80.37 118.90 1 0.5 1 1 1 4.5 No
86 750 18.5 1.31 50 80.73 117.56 1 1 1 1 1 5 No
87 150 10.5 1.33 3 80.81 118.65 1 1 0 1 1 4 No
88 225 13 1.36 7 80.87 120.70 1 0 0 1 1 3 No
89 100 9 1.25 2 80.27 117.62 1 1 0 0 0 2 No
90 150 10.5 1.33 3 80.41 118.65 1 1 1 1 0.5 4.5 No
91 550 29.5 1.19 94 80.62 120.12 1 0.5 1 1 1 4.5 No
92 250 12.5 1.27 8 79.96 120.20 1 1 1 1 0.5 4.5 No
93 150 10 1.22 3 79.24 119.18 1 1 0 1 0 3 No
94 100 8 1.00 1 79.37 119.00 1 1 0 0 0 2 No
95 125 7.5 1.14 1 79.78 115.18 1 0 0 0.5 0.5 2 No
96 100 8.5 1.13 1 78.46 120.28 1 0 0.5 1 1 3.5 No
97 1000 28.5 1.19 159 77.54 118.28 0.5 1 0.5 0.5 0.5 3 No
98 2600 49.5 1.11 1250 76.96 117.78 1 1 1 0.5 1 4.5 Yes
99 3850 58 1.11 2542 76.07 115.94 0.5 1 1 1 1 4.5 No
100 1350 27.5 1.29 200 76.73 125.76 1 1 1 1 0.5 4.5 Yes
101 1100 21 1.21 95 76.93 125.73 1 1 1 1 0.5 4.5 Yes
102 1050 20 1.11 82 77.11 125.89 0.5 1 1 0.5 0.5 3.5 Yes
103 2400 39 1.17 716 77.32 125.97 1 1 1 0.5 0.5 4 Yes
104 1100 22 1.20 104 77.46 126.85 0.5 1 1 0.5 0.5 3.5 Yes
105 550 29 1.15 91 79.24 128.12 0.5 0 1 0.5 0.5 2.5 No
106 600 17 1.27 34 81.34 125.35 1 0.5 0 1 1 3.5 No
107 150 11.5 1.30 4 82.36 127.50 1 1 1 1 1 5 No
108 600 25.5 1.13 77 83.98 133.02 1 0 1 0.5 0.5 3 No
109 500 39 1.11 149 84.31 131.87 1 0.5 1 0.5 0.5 3.5 No
110 125 11.5 1.30 3 81.82 128.45 1 0.5 1 1 1 4.5 No
111 100 8 1.29 1 81.20 129.58 1 1 0 0 0 2 No
112 550 42 1.15 190 81.62 130.38 1 0 1 1 1 4 No
(Continued)
SUBGLACIAL VOLCANOES IN WEST ANTARCTICA
Table 2. Tabulation of subglacial cone coordinates, dimensions and volcanic-interpretation condence factors (see Table 1) (Continued )
Number Height
(m) Average
diameter
(km)
Elongation
ratio Volume
(km
3
)Latitude Longitude Volcano condence factor Previously
identied
12345Sum
113 275 28.5 1.19 44 81.87 130.76 1 0 0 1 1 3 No
114 350 29 1.07 58 82.41 134.85 1 1 1 0.5 0.5 4 No
115 150 10.5 1.33 3 81.10 132.52 1 0.5 1 1 1 4.5 No
116 400 31.5 1.25 78 81.36 133.60 1 1 1 0 0.5 3.5 No
117 100 6 1.40 1 81.64 134.55 1 0 0 0 1 2 No
118 250 15.5 1.07 12 81.55 135.48 1 0 1 1 0.5 3.5 No
119 550 21.5 1.15 50 80.35 131.14 1 1 1 0 1 4 No
120 250 11.5 1.30 6 80.50 134.03 1 0 1 1 1 4 No
121 950 36 1.12 242 80.23 134.29 1 0.5 1 1 0 3.5 No
122 250 30.5 1.03 46 79.57 132.88 1 0 0 0.5 0.5 2 No
123 325 23.5 1.24 35 80.40 136.32 0.5 0 1 1 1 3.5 No
124 400 29 1.00 66 80.08 138.89 0.5 0.5 0 1 0.5 2.5 No
125 275 32.5 1.10 57 79.39 137.82 0.5 0.5 1 1 0.5 3.5 No
126 125 17.5 1.19 8 79.67 138.15 0.5 0 1 0.5 0.5 2.5 No
127 250 19 1.11 18 79.76 139.69 1 0 0 0.5 0.5 2 No
128 400 24 1.18 45 78.70 137.18 0.5 1 0 0.5 0.5 2.5 No
129 300 10.5 1.33 6 78.61 137.87 0.5 0 1 0.5 0.5 2.5 No
130 600 25.5 1.13 77 78.39 139.25 1 0.5 1 1 0.5 4 No
131 425 39.5 1.08 130 79.00 142.10 1 0.5 0 0.5 0.5 2.5 No
132 700 31 1.00 132 78.15 140.91 1 0.5 1 0.5 0.5 3.5 No
133 675 22 1.00 64 77.91 140.89 1 1 1 0.5 0.5 4 No
134 2600 52.5 1.06 1406 73.71 126.54 0 1 1 1 0.5 3.5 Yes
135 400 28 1.15 62 74.69 127.78 0.5 1 1 0.5 0.5 3.5 No
136 200 4.5 1.25 1 75.98 128.21 0 1 1 1 0.5 3.5 Yes
137 1700 47.5 1.16 753 76.11 128.64 0 1 1 1 0.5 3.5 No
138 325 16 1.13 16 75.80 128.57 0 1 1 1 0.5 3.5 No
139 1500 19.5 1.17 112 75.98 129.11 0 1 1 1 0.5 3.5 Yes
140 450 5.5 1.20 3 75.90 129.29 0 1 1 1 0.5 3.5 No
141 1800 36 1.06 458 75.98 132.31 0.5 1 1 0.5 0.5 3.5 Yes
142 900 21 1.00 78 76.24 132.63 0.5 1 1 0.5 0.5 3.5 Yes
143 400 5 1.00 2 76.22 133.14 0 1 1 0.5 0.5 3 No
144 600 13 1.17 20 76.27 135.11 0 1 1 0.5 0.5 3 Yes
145 950 18.5 1.18 64 76.27 136.12 0 1 1 0.5 0.5 3 Yes
146 800 9.5 1.11 14 75.88 137.95 0 1 1 0.5 0.5 3 No
147 275 19.5 1.17 21 75.62 138.08 0 1 1 0.5 0.5 3 No
148 600 8.5 1.13 9 78.09 153.87 1 1 1 1 0.5 4.5 No
149 450 21.5 1.15 41 78.13 155.26 1 1 1 1 0.5 4.5 No
M. VAN WYK DE VRIES ET AL.
150 775 23 1.19 80 77.88 153.60 1 1 1 1 0.5 4.5 No
151 275 16.5 1.06 15 77.89 154.81 1 1 1 1 0.5 4.5 No
152 100 7 1.33 1 78.19 157.00 0 1 1 0.5 0.5 3 No
153 125 18 1.25 8 82.11 154.71 0 0 1 0.5 0.5 2 No
154 100 16.5 1.06 5 81.96 157.64 0 0 1 0.5 0.5 2 No
155 150 24 1.18 17 81.53 163.39 1 1 1 0.5 0.5 4 No
156 225 15 1.00 10 78.00 165.52 0 0.5 0.5 1 0.5 2.5 No
157 100 12 1.18 3 77.18 164.77 0 0.5 0.5 1 0.5 2.5 No
158 1400 34 1.13 318 85.96 163.98 0.5 1 1 0.5 0.5 3.5 Yes
159 400 10.5 1.33 9 78.39 167.56 0.5 1 1 1 0.5 4 Yes
160 325 16.5 1.20 17 78.50 166.04 0 1 1 1 0.5 3.5 Yes
161 1600 29 1.07 264 78.61 165.08 0 1 1 1 0.5 3.5 Yes
162 2050 39.5 1.14 628 78.73 163.67 0 1 1 1 0.5 3.5 Yes
163 2250 33 1.13 481 77.78 168.67 0 1 1 1 0.5 3.5 Yes
164 1800 29.5 1.19 307 77.70 166.83 0 1 1 1 0.5 3.5 Yes
165 1250 21 1.10 108 77.49 166.78 0 1 1 1 0.5 3.5 Yes
166 425 22.5 1.14 42 77.23 167.68 0 1 1 1 0.5 3.5 Yes
167 350 20.5 1.16 29 77.18 166.94 0 1 1 0.5 0.5 3 Yes
168 750 16.5 1.20 40 74.58 164.22 1 1 1 1 0.5 4.5 Yes
169 600 26.5 1.21 83 73.80 169.69 0.5 1 1 1 0.5 4 Yes
170 950 33.5 1.09 209 73.42 164.70 0 1 1 1 0.5 3.5 Yes
171 1550 34.5 1.16 362 72.78 169.89 0 1 1 0.5 0.5 3 Yes
172 750 17.5 1.19 45 71.93 170.41 0 1 1 1 0.5 3.5 Yes
173 500 25.5 1.13 64 76.45 165.16 0 0.5 0.5 0.5 0.5 2 No
174 450 34.5 1.09 105 76.37 166.16 0 0.5 0.5 0.5 0.5 2 No
175 450 13.5 1.25 16 76.12 72.41 0.5 1 1 1 0.5 4 Yes
176 400 9.5 1.38 7 73.68 78.91 0 1 1 0.5 0.5 3 No
177 550 20 1.22 43 73.70 79.43 0.5 1 1 1 0.5 4 Yes
178 300 17 1.27 17 74.67 78.72 0.5 1 1 1 0.5 4 Yes
Average 621 21.3 1.18 121 77.56 120.28 0.69 0.69 0.71 0.74 0.57 3.40
The nal column identies whether the cone was a previously recognized volcano (Yes) or a new discovery (No). Most of the previously identied volcanoes are catalogued in LeMasurier et al. (1990).
SUBGLACIAL VOLCANOES IN WEST ANTARCTICA
unknown volcanic edices across the ice-shrouded
WARS.
Extent and activity of subglacial volcanism
We have identied at least 138 likely volcanic
edices distributed throughout the WARS. This
represents a signicant advance on the total of 47
identied volcanoes across the whole of West Ant-
arctica, most of which are visible at the surface and
are situated in Marie Byrd Land and the Transantarc-
tic Mountains (LeMasurier et al. 1990). The wide
distribution of volcanic structures throughout the
WARS, along with the presence of clusters of
Fig. 3. The upper panel shows an echogram from NASAs Icebridge mission (NSIDC 2014) that shows generally
good agreement between a cone on the echogram and on the Bedmap2 data. The lower panel shows an echogram
from Corr & Vaughan (2008) with basal topography picking out two cones; the dark layer above the bed is tephra
believed to have erupted around 2000 years ago.
Table 3. Statistical comparison of the morphologies of the cones identied in this study identied as volcanoes
Height
(m) Average
diameter (km) Axis
ratio Volume
(km
3
)Condence
factor
(a) (b) (a) (b) (a) (b) (a) (b) (a)
Average 701 940 21.9 17.1 1.19 2.11 144 150 3.75
Standard Deviation 641 670 10.7 11.6 0.09 0.81 345 371 0.56
Median 475 810 20.5 15.3 1.17 1.98 42 31 3.5
Minimum 100 100 4.5 2.3 1.00 1.13 0.5 0.2 3
Maximum 3850 3030 58.5 63.3 1.44 5.23 2542 3086 5
Comparison with: (a) those from a global database of shield volcanoes; and (b) Grosse et al. (2014). The two are similar, apart from the
long-short axis ratio; our cones are, on average, more circular than shield volcanoes elsewhere. This could be linked to specic glaciovol-
canic eruption mechanisms, but is most likely a data bias due to our detection methods excluding more elliptical edices.
M. VAN WYK DE VRIES ET AL.
volcanism concentrated within the Marie Byrd
Land dome, is markedly similar to the East African
Rift System, which is also >2000 km in length and
anked by the Ethiopian and Kenyan domes (Fig.
1b) (Siebert & Simkin 2002; Ebinger 2005). Mor-
phologically, the volcanoes have volumeheight
characteristics and basal diameters that closely
match those of rift volcanoes around the world
(Fig. 5; Table 3). Bearing in mind that data paucity
beneath the Ross Ice Shelf precluded meaningful
analysis of a signicant terrain also considered to
be part of the WARS, the total region that has expe-
rienced volcanism is likely to be considerably larger
than that we have identied here.
Cone 91
Cone 60
Cone 21
Mouna Kea, Hawaii
Erta Ale, Ethiopia
Marsabit, Kenya
5 km 10 km 15 k m 20 km 25 km 30 km
1000 m
1000 m
1000 m
1000 m
1000 m
1000 m
Fig. 4. Cross-sections of three cones from this study (numbers 21, 60 and 91: see Fig. 2 and Table 2 for more details
and locations) and three prominent shield volcanoes, namely Mauna Kea (Hawaii), Erta Ale and Marsabit (East
African Rift).
Fig. 5. Volume/height chart of the cones from this study (crosses) superimposed over data from volcanoes
worldwide (Grosse et al. 2014). The cones closely t the morphology data for shield volcanoes, as would be expected
for basalt-dominated rift volcanism.
SUBGLACIAL VOLCANOES IN WEST ANTARCTICA
The activity of the WARS has been the subject of
a longstanding debate, with one side advocating a
largely inactive rift (LeMasurier 2008) and others
suggesting large-scale volcanism (Behrendt et al.
2002). The arguments in favour of an inactive rift
are based on the anomalously low elevation of the
WARS compared to other active continental rifts
(Winberry & Anandakrishnan 2004; LeMasurier
2008) and the relative absence of basalt pebbles
recovered from boreholes (LeMasurier pers. comm.
2015). Conversely, high regional heat uxes (Sha-
piro & Ritzwoller 2004; Schroeder et al. 2014), geo-
magnetic anomalies (Behrendt et al. 2002) and
evidence of recent subglacial volcanism (Blanken-
ship et al. 1993; Corr & Vaughan 2008) suggest
that the rift is currently active. This study provides
evidence of a large number of subglacial volcanoes,
with their quasi-conical shield volcano type geome-
tries still intact. The largely uneroded nature of the
cones suggests that many may be of Pleistocene
age or younger, which supports the argument that
the rift remains active today.
From this study, we are not able to determine
whether the different volcanoes are active or not;
however, the identication of multiple new volcanic
edices, and the improved regional sense of their
geographical spread and concentration across the
WARS, may guide future investigation of their
activity. Several previous studies have suggested
that the Marie Byrd Land massif is supported by
particularly low-density mantle, possibly compris-
ing a volcanic hotspot(Hole & LeMasurier
1994; Winberry & Anandakrishnan 2004). Tephra
layers recovered from the Byrd Ice Core near the
WAIS divide suggest that multiple Marie Byrd
Land volcanoes were active in the Late Quaternary
(Wilch et al. 1999), while recent seismic activity
in Marie Byrd Land has been interpreted as cur-
rently active volcanism (Lough et al. 2013). In the
Pine Island Glacier catchment, strong radar-sounded
englacial reectors have been interpreted as evi-
dence of a local eruption that occurred approxi-
mately 20002400 years ago (Fig. 3) (see Corr &
Vaughan 2008) while, on the opposite rift ank in
the Transantarctic Mountains, Mount Erebus com-
prises a known active volcano located above another
potential volcanic hotspot (Gupta et al. 2009). Vol-
canism across the region is also likely to contribute
to the elevated geothermal heat uxes that have been
inferred to underlie much of the WAIS (Shapiro &
Ritzwoller 2004; Fox Maule et al. 2005; Schroeder
et al. 2014). The deployment of broadband seismics
to recover the mantle structure beneath the WAIS is
now showing great promise (e.g. Heeszel et al.
2016), and our map of potential volcanic locations
could help target further installations directed to-
wards improved monitoring of the continents sub-
glacial volcanic activity.
Implications for ice stability and future
volcanism
The wide spread of volcanic edices and the possi-
bility of extensive volcanism throughout the
WARS also provides potential inuences on the
stability of the WAIS. Many parts of the WAIS over-
lie basins that descend from sea level with distance
inland, lending the ice sheet a geometry that is
prone to runaway retreat (Bamber et al. 2009;
Alley et al. 2015). Geological evidence points to
the likelihood that the WAIS experienced extensive
retreat during Quaternary glacial minima (Naish
et al. 2009) and concurrently contributed several
metres to global sea-level rise (OLeary et al.
2013). Currently, the WAIS may be undergoing
another such wholesale retreat, as ice in the Pacic-
facing sector has consistently been retreating from
the time of the earliest aerial and satellite observa-
tions (Rignot 2002; McMillan et al. 2014; Mouginot
et al. 2014). We do not consider it likely that volca-
nism has played a signicant role in triggering
the current retreat, for which there is compelling
evidence that the forcing has initiated from the mar-
gins (Turner et al. 2017), but we do propose that
subglacial volcanism has the potential to inuence
future rates of retreat by (1) producing enhanced
basal melting that could impact upon basal ice
motion and (2) providing edices that may act to
pin retreat.
On the rst of these possibilities, some authors
have suggested that active subglacial volcanism,
through providing enhanced basal melting that
might lubricatebasal motion, could play a role in
WAIS instability (Blankenship et al. 1993; Vogel
et al. 2006; Corr & Vaughan 2008). A possible anal-
ogy is provided by subglacial volcanism in Iceland,
where subglacial eruptions have been known to
melt basal ice, ood the basal interface and induce
periods of enhanced ice ow (e.g. Magnússon
et al. 2007; Einarsson et al. 2016); however, in Ice-
lands ice caps the ice is considerably thinner than in
the WAIS and, hence, more prone to subglacial-
melt-induced uplift. Nevertheless, there is evidence
to suggest that changes to subglacial water distribu-
tion can occur beneath the WAIS, and that they can
sometimes have profound impacts on ice dynamics:
examples are ice-dynamic variability over subglacial
lakes (e.g. Siegfried et al. 2016) or the suggestion
that subglacial water pulses may have been responsi-
ble for historical occurrences of ice-stream piracy
(e.g. Anandakrishnan & Alley 1997; Vaughan et al.
2008). Much recent attention has focused on the
drainage of subglacial lakes comprising plausible
triggers of such dynamic changes, but subglacial
eruptions may represent another pulsed-water source
whose occurrence has rarely, if ever, been factored
into ice-sheet models. Even inactive or dormant
M. VAN WYK DE VRIES ET AL.
volcanism has the potential to inuence ice ow by
increasing heat ux to the subglacial interface; this
may generate a basal melt cavity and enhance ice
ow (Bourgeois et al. 2000; Schroeder et al. 2014).
On the other hand, volcanic edices, whether
active or not, stand as signicant protuberances
which may act geometrically as stabilizing inu-
ences on ice retreat. Numerical models used to pro-
ject potential rates of WAIS retreat show that, once
initiated, ice retreat will continue unabated as long
as the ice bed is smooth and downslopes inland,
but that any increase in roughness or obstacle in
the bed can act to delay or stem retreat (Ritz et al.
2015; Nias et al. 2016). We have identied here
a number of volcanic edices sitting within the
WAISdeep basins; these edices, which are likely
to owe their existence to volcanism, could represent
some of the most inuential pinning points for past
and future ice retreat.
Looking ahead, the thinning and potential
removal of ice cover from the WARS volcanic prov-
ince could have profound impacts for future volcanic
activity across the region. Research in Iceland has
shown that with thinning ice cover, magma pro-
duction has increased at depth as a response to
decompression of the underlying mantle (Jull &
McKenzie 1996; Schmidt et al. 2013). Moreover,
there is evidence that, worldwide, volcanism is
most frequent in deglaciating regions as the overbur-
den pressure of the ice is rst reduced and then
removed (Huybers & Langmuir 2009; Praetorius
et al. 2016). Unloading of the WAIS from the
WARS therefore offers signicant potential to
increase partial melting and eruption rates through-
out the rifted terrain. Indeed, the concentration of
volcanic edices along the WARS could be con-
strued as evidence that such enhanced volcanic activ-
ity was a feature of Quaternary minima. This raises
the possibility that in a future of thinning ice cover
and glacial unloading over the WARS, subglacial
volcanic activity may increase and this, in turn,
may lead to enhanced water production and contrib-
ute to further potential ice-dynamical instability.
Conclusions
By applying morphometric analysis to a digital ele-
vation model of the West Antarctic Rift System,
and assessing the results with respect to auxiliary
information from ice-surface expressions to aero-
geophysical data, we have identied 138 subglacial
volcanic edices spread throughout the rift. The
volcanoes are widely distributed in the broad rift
zone, with particular concentrations in Marie
Byrd Land and along the central WARS axis. The
results demonstrate that the West Antarctic Ice
Sheet shrouds one of the worlds largest volcanic
provinces, similar in scale to the East African
Rift System. The overall volcano density beneath
West Antarctica was found to be one edice per
18 500 ± 500 km
2
, with a central belt along the
rifts central sinuous ridge containing one edice
per 7800 ± 400 km
2
. The presence of such a volcanic
belt traversing the deepest marine basins beneath the
centre of the West Antarctic Ice Sheet could prove to
be a major inuence on the past behaviour and future
stability of the ice sheet.
We would like to thank John Smellie and Matteo Spagnolo
for insightful and thorough reviews of a rst draft of this
manuscript that contributed, we hope, to a much improved
paper.
References
ALLEY, R.B., ANANDAKRISHNAN,S.ET AL. 2015. Oceanic
forcing of ice sheet retreat: West Antarctica and more.
Annual Reviews in Earth and Planetary Sciences,43,
207231.
ANANDAKRISHNAN,S.&ALLEY, R.B. 1997. Stagnation of ice
stream C, West Antarctica by water piracy. Geophysical
Research Letters,24, 265268.
BAMBER, J.L., RIVA, R.E.M., VERMEERSEN, B.L.A. & LE
BROCQ, A.M. 2009. Reassessment of the potential sea-
level rise from a collapse of the West Antarctic Ice
Sheet. Science,324, 901903.
BEHRENDT, J.C., LEMASURIER, W.E., COOPER, A.K., TESSEN-
SOHN, F., TREHU,A.&DAMASKE, D. 1991. Geophysical
studies of the West Antarctic Rift System. Tectonics,
10, 12571273.
BEHRENDT, J.C., FINN, C.A., BLANKENSHIP, D.D. & BELL, R.E.
1998. Aeromagnetic evidence for a volcanic caldera(?)
complex beneath the divide of the West Antarctic Ice
Sheet. Geophysical Research Letters,25, 43854388.
BEHRENDT, J.C., BLANKENSHIP, D.D., MORSE, D.L., FINN,
C.A. & BELL, R.E. 2002. Subglacial volcanic features
beneath the West Antarctic Ice Sheet interpreted from
aeromagnetic and radar ice sounding. In:S
MELLIE, J.L.
&C
HAPMAN, M.G. (eds) VolcanoIce Interaction on
Earth and Mars. Geological Society, London, Special
Publications, 202, 337355, https://doi.org/10.
1144/GSL.SP.2002.202.01.17
BINGHAM, R.G. & SIEGERT, M.J. 2009. Quantifying subgla-
cial bed roughness in Antarctica: implications for ice-
sheet dynamics and history. Quaternary Science
Reviews,28, 223236.
BINGHAM, R.G., FERRACCIOLI, F., KING, E.C., LARTER, R.D.,
PRITCHARD, H.D., SMITH, A.M. & VAUGHAN, D.G. 2012.
Inland thinning of West Antarctic Ice Sheet steered
along subglacial rifts. Nature,487, 468471.
BLANKENSHIP, D.D., BROZENA, R.B., BEHRENDT, J.C. & FINN,
C.A. 1993. Active volcanism beneath the West Antarc-
tic ice sheet and implications for ice-sheet stability.
Nature,361, 526529.
BO, S., SIEGERT, M.J. ET AL. 2009. The Gamburtsev moun-
tains and the origin and early evolution of the Antarctic
Ice Sheet. Nature,459, 690693.
BOURGEOIS, O., DAUTEUIL,O.&VLIET-LANOE, B.V. 2000.
Geothermal control on ow patterns in the Last Glacial
SUBGLACIAL VOLCANOES IN WEST ANTARCTICA
Maximum ice sheet of Iceland. Earth Surface Processes
and Landforms,25,5976.
BROZ, P., HAUBER, E., PLATZ,T.&BALME, M. 2015. Evi-
dence for Amazonian highly viscous lavas in the south-
ern highlands on Mars. Earth and Planetary Science
Letters,415, 200212.
CHANG, M., JAMIESON, S.S.R., BENTLEY, M.J. & STOKES,
C.R. 2015. The surcial and subglacial geomorphology
of western Dronning Maud Land, Antarctica. Journal of
Maps,12, 892903.
CORR, H.F.J. & VAUGHAN, D.G. 2008. A recent volcanic
eruption beneath the West Antarctic ice sheet. Nature
Geoscience,1, 122125.
DALZIEL, I.W.D. 2006. On the extent of the active West Ant-
arctic Rift System. Terra Antartica Reports,12,193202.
DAMIANI, T.M., JORDAN, T.A., FERRACCIOLI, F., YOUNG, D.A.
&B
LANKENSHIP, D.D. 2014. Variable crustal thickness
beneath Thwaites Glacier revealed from airborne gra-
vimetry, possible implications for geothermal heat
ux in West Antarctica. Earth and Planetary Science
Letters,407, 109122.
DERYDT, J., GUDMUNDSSON, G.H., CORR, H.F.J. & CHRISTOF-
FERSEN, P. 2013. Surface undulations of Antarctic ice
streams tightly controlled by bedrock topography. The
Cryosphere,7, 407417.
EBINGER, C.J. 2005. Continental break-up: the East African
perspective. Astronomical Geophysics,46, 216221.
EBINGER, C., AYELE,A.ET AL. 2010. Length and timescales
of rift faulting and magma intrusion: the Afar Rifting
cycle from 2005 to present. Annual Review of Earth
and Planetary Sciences,38, 437464.
EBINGER, C.J., VAN WIJK,J.&KEIR, D. 2013. The time scales
of continental rifting: implications for global processes.
In:B
ICKFORD, M.E. (ed.) The Web of Geological Sci-
ences: Advances, Impacts, and Interactions. Geological
Society of America, Special Papers, 500, 371396.
EINARSSON, B., MAGNÚSSON, E., ROBERTS, M.J., PÁLSSON, F.,
THORSTEINSSON,T.&JÓHANNSSON, T. 2016. A spectrum
of jökulhlaup dynamics revealed by GPS measure-
ments. Annals of Glaciology,57,4761.
ELLIOTT, D.H. 2013. The geological and tectonic evolution
of the Transantarctic Mountains: a review. In:H
AM-
BREY, M.J., BARKER, P.F., BARRETT, P.J., BOWMAN, V.,
DAVIES, B., SMELLIE, J.L. & TRANTER, M. (eds) Antarctic
Palaeoenvironments and Earth-Surface Processes.
Geological Society, London, Special Publications,
381,735, https:// doi.org/10.1144/SP381.14
ELLIS,M.&KING, G. 1991. Structural control of ank vol-
canism in continental rifts. Science,254, 839842.
ELY, J.C., CLARK, C.D. ET AL. 2016. Do subglacial bedforms
comprise a size and shape continuum? Geomorphology,
257, 108119.
FAVALLI, M., KARÁTSON, D., YEPES,J.&NANNIPIERI,L.
2014. Surface tting in geomorphology examples
for regular-shaped volcanic landforms. Geomorphol-
ogy,221, 139149.
FITZGERALD, P.G. 2002. Tectonics and landscape evolution
of the Antarctic plate since the breakup of Gondwana,
with an emphasis on the West Antarctic Rift System
and the Transantarctic Mountains. Royal Society of
New Zealand Bulletin,35, 453469.
FOX MAULE, C., PURUCKER, M., OLSEN,N.&MOSEGAARD,K.
2005. Heat ux anomalies in Antarctica revealed from
satellite magnetic data. Science,309, 464467.
FRETWELL, P., PRITCHARD, H.D. ET AL. 2013. Bedmap2:
improved ice bed, surface and thickness datasets for
Antarctica. The Cryosphere,7, 375393.
GLOBAL VOLCANISM PROGRAM 2013. VENZKE, E. (ed.) Volca-
noes of the World, v. 4.5.3. Smithsonian Institution,
https://doi.org/10.5479/si.GVP.VOTW4-2013
GROSSE, P., EUILLADES, P.A., EUILLADES, L.D. & VAN WYK DE
VRIES, B. 2014. A global database of composite volcano
morphology. Bulletin of Volcanology,76, 784.
GUPTA, S., ZHAO,D.&RAI, S.S. 2009. Seismic imaging of
the upper mantle under the Erebus hotspot in Antarc-
tica. Gondwana Research,16, 109118.
HEESZEL, D.S., WIENS, D.A. ET AL. 2016. Upper mantle struc-
ture of central and West Antarctica from array analysis
of Rayleigh wave phase velocities. Journal of Geophys-
ical Research,121, 17581775.
HICKSON, C.J. 2000. Physical controls and resulting mor-
phological forms of Quaternary ice-contact volcanoes
in western Canada. Geomorphology,32, 239261.
HOLE, M.J. & LEMASURIER, W.E. 1994. Tectonic controls
on the geochemical composition of the Cenozoic,
mac volcanic alkaline rocks from West Antarctica.
Contributions to Mineralogy and Petrology,117,
182202.
HUYBERS,P.&LANGMUIR, C. 2009. Feedback between
deglaciation, volcanism, and atmospheric CO
2
.Earth
and Planetary Science Letters,286, 479491.
JAMIESON, S.S.R., SUGDEN, D.E. & HULTON, N.R.J. 2010.
The evolution of the subglacial landscape of Antarctica.
Earth and Planetary Science Letters,293,127.
JAMIESON, S.S.R., STOKES, C.R. ET AL. 2014. The glacial geo-
morphology of the Antarctic ice sheet bed. Antarctic
Science,26, 724741.
JAMIESON, S.S.R., ROSS,N.ET AL. 2016. An extensive sub-
glacial lake and canyon system in Princess Elizabeth
Land, East Antarctica. Geology,44,8790.
JORDAN, T.A., FERRACCIOLI, F., VAUGHAN, D.G., HOLT, J.W.,
CORR, H., BLANKENSHIP, D.D. & DIEHL, T.M. 2010.
Aerogravity evidence for major crustal thinning under
the Pine Island Glacier region (West Antarctica). Geo-
logical Society of America Bulletin,122, 714726.
JULL,M.&MCKENZIE, D. 1996. The effect of deglaciation
on mantle melting beneath Iceland. Journal of Geo-
physical Research,101, 2181521828.
KALBERG, T., GOHL, K., EAGLES,G.&SPIEGEL, C. 2015. Rift
processes and crustal structure of the Amundsen Sea
Embayment, West Antarctica, from 3D potential eld
modelling. Marine Geophysical Research,36,
263279.
KIM, H.R., VON FRESE, R.R.B., TAYLOR, P.T., GOLYNSKY,
A.V., GAYA-PIQUÉ, L.R. & FERRACCIOLI, F. 2007.
Improved magnetic anomalies of the Antarctic litho-
sphere from satellite and near-surface data. Geophysical
Journal International,171, 119126.
LEMASURIER, W.E. 2008. Neogene extension and basin
deepening in the West Antarctic rift inferred from com-
parisons with the East African rift and other analogs.
Geology,36, 247250.
LEMASURIER, W.E. 2013. Shield volcanoes of Marie Byrd
Land, West Antarctic rift: oceanic island similarities,
continental signature, and tectonic controls. Bulletin
of Volcanology,75, 726.
LEMASURIER, W.E., THOMSON, J.W., BAKER, P.E., KYLE,
P.R., ROWLEY, P.D., SMELLIE, J.L. & VERWOERD, W.J.
M. VAN WYK DE VRIES ET AL.
1990. Volcanoes of the Antarctic Plate and Southern
Oceans Antarctic. American Geophysical Union, Ant-
arctic Research Series, 48.
LINDBACK,K.&PETTERSSON, R. 2015. Spectral roughness
and glacial erosion of a land-terminating section of the
Greenland Ice Sheet. Geomorphology,238,149159.
LOUGH, A.C. & OTHERS. 2013. Seismic detection of an active
subglacial magmatic complex in Marie Byrd Land, Ant-
arctica. Nature Geoscience,6, 10311035.
MAGNÚSSON, E., ROTT, H., BJÖRNSSON,H.&PÁLSSON,F.
2007. The impact of jökulhlaups on basal sliding
observed by SAR interferometry on Vatnajökull, Ice-
land. Journal of Glaciology,53, 232240.
MCKNIGHT, S.B. & WILLIAMS, S.N. 1997. Old cinder cone or
young composite volcano?: The nature of Cerro Negro,
Nicaragua. Geology,25, 339342.
MCMILLAN, M., SHEPHERD,A.ET AL. 2014. Increased ice
losses from Antarctica detected by CryoSat-2. Geo-
physical Research Letters,41, 38993905.
MOUGINOT, J., RIGNOT,E.&SCHEUCHL, B. 2014. Sustained
increase in ice discharge from the Amundsen Sea
Embayment, West Antarctica, from 1973 to 2013. Geo-
physical Research Letters,41, 15761584.
NAISH, T., POWELL,R.ET AL. 2009. Obliquity-paced Pliocene
West Antarctic ice sheet oscillations. Nature,458,
322328.
NIAS, I.J., CORNFORD, S.L. & PAYNE, A.J. 2016. Contrasting
the modelled sensitivity of the Amundsen Sea Embay-
ment ice streams. Journal of Glaciology,62, 552562.
NSIDC 2014. IceBridge Accumulation Radar L1B Geolo-
cated Radar Echo Strength Proles. Version 2,
IRMCR1B. NASA National Snow and Ice Data Center,
Distributed Active Archive Center, Boulder CO, USA
(updated 2015).
OLEARY, M.J., HEARTY, P.J., THOMPSON, W.G., RAYMO,
M.E., MITROVICA, J.X. & WEBSTER, J.M. 2013. Ice
sheet collapse following a prolonged period of stable
sea level during the last interglacial. Nature Geosci-
ence,6, 796800.
PEDERSEN, G.B.M. & GROSSE, P. 2014. Morphometry of
subaerial shield volcanoes and glaciovolcanoes from
Reykjanes Peninsula, Iceland: effects of eruption envi-
ronment. Journal of Volcanology and Geothermal
Research,282, 115133.
POLLARD,D.&DECONTO, R.M. 2009. Modelling West Ant-
arctic ice sheet growth and collapse through the past
ve million years. Nature,458, 329332.
PRAETORIUS, S., MIX,A.ET AL. 2016. Interaction between cli-
mate, volcanism, and isostatic rebound in Southeast
Alaska during the last deglaciation. Earth and Plane-
tary Science Letters,452,7989.
RIGNOT, E. 2002. Ice-shelf changes in Pine Island Bay,
Antarctica, 19472000. Journal of Glaciology,48,
247256.
RIGNOT, E., MOUGINOT,J.&SCHEUCHL, B. 2011. Ice ow of
the Antarctic Ice Sheet. Science,333, 14271430.
RITZ, C., EDWARDS, T.L., DURAND, G., PAYNE, A.J., PEYAUD,
V. & HINDMARSH, R.C.A. 2015. Potential sea-level rise
from Antarctic ice-sheet instability constrained by
observations. Nature,528, 115118.
ROSE, K.C., FERRACCIOLI,F.ET AL. 2013. Early East Antarc-
tic Ice Sheet growth recorded in the landscape of the
Gamburtsev Subglacial Mountains. Earth and Plane-
tary Science Letters,375,112.
ROSE, K.C., ROSS,N.ET AL. 2014. A temperate former
West Antarctic ice sheet suggested by an extensive
zone of subglacial meltwater channels. Geology,42,
971974.
ROSS, N., JORDAN, T.A. ET AL. 2014. The Ellsworth subgla-
cial highlands: inception and retreat of the West Antarc-
tic Ice Sheet. Geological Society of America Bulletin,
126,315.
SCAMBOS, T., HARAN, T., FAHNESTOCK, M., PAINTER,T.&
BOHLANDER, J. 2007. MODIS-based Mosaic of Antarc-
tica (MOA) data sets: Continent-wide surface morphol-
ogy and snow grain size. Remote Sensing of
Environment,111, 242257.
SCHEINERT, M., FERRACCIOLI,F.ET AL. 2016. New Antarctic
gravity anomaly grid for enhanced geodetic and geo-
physical studies in Antarctica. Geophysical Research
Letters,43, 600610.
SCHMIDT, P., LUND, B., HIERONYMUS, C., MACLENNAN, J.,
ÁRNARDÓTTIR,T.&PAGLI, C. 2013. Effects of pre-
sent day deglaciation in Iceland on mantle melt pro-
duction rates. Journal of Geophysical Research,118,
33663379.
SCHROEDER,D.M.,BLANKENSHIP, D.D.,YOUNG,D.A.&QUAR-
TINI, E. 2014.Evidence for elevated andspatially variable
geothermal ux beneath the West Antarctic Ice Sheet.
Proceedings of the National Academy of Sciences of
the United States of America,111,90709072.
SHAPIRO, N.M. & RITZWOLLER, M.H. 2004. Inferring surface
heat ux distributions guided by a global seismic
model: particular application to Antarctica. Earth and
Planetary Science Letters,223, 213224.
SIDDOWAY, C.S. 2008. Tectonics of the West Antarctic rift
system: new light on the history and dynamics of dis-
tributed intracontinental extension. In:C
OOPER, A.K.,
BARRETT, P.J., STAGG, H., STOREY, B., STUMP,E.&
WISE, W. (eds) Antarctica: A Keystone in a Changing
World, Proceedings of the 10th International Sympo-
sium on Antarctic Earth Sciences. The National Acad-
emies Press, Washington, DC, 91114.
SIEBERT,L.&SIMKIN, T. 2002. Volcanoes of the World: an
Illustrated Catalog of Holocene Volcanoes and their
Eruptions. Smithsonian Institution, Global Volcanism
Program Digital Information Series, GVP-3.
SIEGFRIED, M.R., FRICKER, H.A., CARTER, S.P. & TULACZYK,
S. 2016. Episodic ice velocity uctuations triggered by
a subglacial ood in West Antarctica. Geophysical
Research Letters,43, 26402648.
SMELLIE, J.L. 2008. Basaltic subglacial sheet-like
sequences: Evidence for two types with different impli-
cations for the inferred thickness of associated ice.
Earth-Science Reviews,88,6088.
SMELLIE, J.L. & EDWARDS, B.R. 2016. Glaciovolcanism
on Earth and Mars. Cambridge University Press,
Cambridge.
SPIEGEL, C., LINDOW,J.ET AL. 2016. Tectonomorphic evolu-
tion of Marie Byrd Land Implications for Cenozoic
rifting activity and onset of West Antarctic glaciation.
Global and Planetary Change,145,98115.
STRETCH, R.C., MITCHELL, N.C. & PORTARO, R.A. 2006.
A morphometric analysis of the submarine volcanic
ridge south-east of Pico Island, Azores. Journal of Vol-
canology and Geothermal Research,156,12, 3554.
STUDINGER, M., BELL, R.E., BLANKENSHIP, D.D., FINN, C.A.,
ARKO, R.A., MORSE, D.L. & JOUGHIN, I. 2001.
SUBGLACIAL VOLCANOES IN WEST ANTARCTICA
Subglacial sediments: a regional geologic template for
ice ow in West Antarctica. Geophysical Research Let-
ters,28, 34933496.
STUDINGER, M., BELL, R.E., FINN, C.A. & BLANKENSHIP, D.D.
2002. Mesozoic and Cenozoic extensional tectonics of
the West Antarctic Rift System from high-resolution
airborne geophysical mapping. Royal Society of New
Zealand Bulletin,35, 563569.
TURNER, J., ORR, A., GUDMUNDSSON, G.H., JENKINS, A., BING-
HAM, R.G., HILLENBRAND, C.-D. & BRACEGIRDLE, T.J.
2017. Atmosphere-ice-ocean interactions in the
Amundsen Sea Embayment, West Antarctica. Reviews
of Geophysics,55, 235276.
VAUGHAN, D.G., CORR, H.F.J., SMITH, A.M., PRITCHARD,H.
D. & SHEPHERD, A. 2008. Flow-switching and water
piracy between Rutford Ice Stream and Carlson Inlet,
West Antarctica. Journal of Glaciology,54,4148.
VOGEL, S.W., TULACZYK, S., CARTER, S., RENNE, P., TURRIN,
B. & GRUNOW, A. 2006. Geologic constraints on
the existence and distribution of West Antarctic subgla-
cial volcanism. Geophysical Research Letters,33,
L23501.
WARDELL, L.J., KYLE, P.R. & CHAFFIN, C. 2014. Carbon
dioxide and carbon monoxide emission rates from an
alkaline intra-plate volcano: Mt. Erebus, Antarctica.
Journal of Volcanology and Geothermal Research,
131, 109121.
WILCH, T.I., MCINTOSH, W.C. & DUNBAR, N.W. 1999. Late
Quaternary volcanic activity in Marie Byrd Land:
potential
40
Ar/
39
Ar-dated time horizons in West Ant-
arctic ice and marine cores. Geological Society of Amer-
ica Bulletin,111, 15631580.
WINBERRY, J.P. & ANANDAKRISHNAN, S. 2004. Crustal struc-
ture of the West Antarctic Rift System and Marie Byrd
Land hotspot. Geology,32, 977980.
YOUNG, D.A. & OTHERS. 2011. A dynamic early East Ant-
arctic Ice Sheet suggested by ice-covered fjord land-
scapes. Nature,474,7275.
M. VAN WYK DE VRIES ET AL.
... according to geomagnetic evidence-just 30 and only 30, hotspots have been active and every hotspot was associated with a huge local volcanic activity that, however, later eventually continued, although in general with no equivalent comparably violent paroxysm. This feature is suggestive that, after the first removal of the "plug", the hotspot no more affords to fully recover and reset the former energy reservoir 27 . ...
... Hence, for the time being, the "mantle convection" concept is only speculative and must be neglected or rebutted. 27 A conspicuous literature exists dealing with hotspot definition and also with a speculated hotspot framework and with the relative drift between hotspots. No final evidence and agreement were ever attained, not even on the total number of hotspots. ...
... Discoveries of hydrothermal activity in the waters around Antarctica and confined by the Polar Front (defined as Southern Ocean in Talley et al., 2011), have been made along Antarctic mid-ocean ridges and back-arc spreading centres since the early 2000s (e.g., German et al., 2000;Rogers and Linse, 2014;Hahm et al., 2015;Park et al., 2021), the West Antarctic Rift System (e.g., Bohrmann et al., 1999, Van Wyk de Vries et al., 2017 and the South Sandwich Island arc (e.g., Leat et al., 2000;Cole et al., 2014;Linse et al., 2019). More recently influence of hydrothermal activity in the Southern Ocean has been reported on not only bathyal chemosynthetic ecosystems Linse et al., 2019) but also pelagic ecosystems via massive surface phytoplankton blooms (e.g., Ardyna et al., 2019;Schine et al. 2021). ...
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... The basins are associated with large numbers of subglacial lakes 18 In the Siple Coast region (Fig. 3c), the map shows a sedimentary basin interspersed with extensive volcanoes 15 , re ecting the volcanic-sedimentary nature of the West Antarctic Rift System 26 . The overlying ice streams are characterised by rapid changes in the ice-sheet state controled by the till property variations coupled with subglacial hydrology 27,28 . ...
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The study of volcano-ice interactions, or 'glaciovolcanism', is a field experiencing exponential growth. This comprehensive volume presents a discussion of the distinctive processes and characteristics of glaciovolcanic eruptions, their products, and landforms, with reference to both terrestrial and Mars occurrences. Supported by abundant diagrams and photos from the authors' extensive collections, this book outlines where eruptions have occurred and will occur in the future on Earth, the resulting hazards that are unique to volcano-ice interactions, and how the deposits are used to unravel planetary palaeoclimatic histories. It has a practical focus on lithofacies, glaciovolcanic edifice morphometry and construction, and applications to palaeoenvironmental studies. Providing the first global summary of past and current work, this book also identifies those areas in need of further research, making this an ideal reference for academic researchers and postgraduate students, in the fields of volcanology, glaciology, planetary science and palaeoenvironmental studies. Provides the first comprehensive glaciovolcanic lexicon of terminology and an extensive bibliography, allowing readers to quickly identify access points into the literature Uses a combination of qualitative and quantitative descriptions of important physical and chemical processes, making it accessible to a broad range of readers Outlines critical areas for future research, acting as a guide for student projects and to focus new research efforts. © John L. Smellie and Benjamin R. Edwards 2016. All right Reserved.
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