Hotspots are anomalous regions of volcanism at Earth’s surface that show no obvious association with tectonic plate boundaries. Classic examples include the Hawaiian–Emperor chain and the Yellowstone–Snake River Plain province. The majority are believed to form as Earth’s tectonic plates move over long-lived mantle plumes: buoyant upwellings that bring hot material from Earth’s deep mantle to its surface1. It has long been recognized that lithospheric thickness limits the rise height of plumes2,3,4 and, thereby, their minimum melting pressure. It should, therefore, have a controlling influence on the geochemistry of plume-related magmas, although unambiguous evidence of this has, so far, been lacking. Here we integrate observational constraints from surface geology, geochronology, plate-motion reconstructions, geochemistry and seismology to ascertain plume melting depths beneath Earth’s longest continental hotspot track, a 2,000-kilometre-long track in eastern Australia that displays a record of volcanic activity between 33 and 9 million years ago5,6, which we call the Cosgrove track. Our analyses highlight a strong correlation between lithospheric thickness and magma composition along this track, with: (1) standard basaltic compositions in regions where lithospheric thickness is less than 110 kilometres; (2) volcanic gaps in regions where lithospheric thickness exceeds 150 kilometres; and (3) low-volume, leucitite-bearing volcanism in regions of intermediate lithospheric thickness. Trace-element concentrations from samples along this track support the notion that these compositional variations result from different degrees of partial melting, which is controlled by the thickness of overlying lithosphere. Our results place the first observational constraints on the sub-continental melting depth of mantle plumes and provide direct evidence that lithospheric thickness has a dominant influence on the volume and chemical composition of plume-derived magmas.
Subscribe to Journal
Get full journal access for 1 year
only $3.90 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
Morgan, W. J. Convection plumes in the lower mantle. Nature 230, 42–43 (1971)10.1038/230042a0
Davies, G. F. Thermomechanical erosion of the lithosphere by mantle plumes. J. Geophys. Res. 99, 15709–15722 (1994)
Farnetani, C. G. & Richards, M. A. Thermal entrainment and melting in mantle plumes. Earth Planet. Sci. Lett. 136, 251–267 (1995)
White, R. S. & McKenzie, D. Mantle plumes and flood basalts. J. Geophys. Res. 100, 17543–17585 (1995)
Cohen, B. E., Knesel, K. M., Vasconcelos, P. M., Thiede, D. S. & Hergt, J. M. 40Ar/39Ar constraints on the timing and origin of Miocene leucitite volcanism in southeastern Australia. Aust. J. Earth Sci. 55, 407–418 (2008)
Cohen, B. E., Knesel, K. M., Vasconcelos, P. M. & Schellart, W. P. Tracking the Australian plate motion through the Cenozoic: constraints from 40Ar/39Ar geochronology. Tectonics 32, 1371–1383 (2013)
Duncan, R. A. & Richards, M. A. Hotspots, mantle plumes, flood basalts and true polar wander. Rev. Geophys. 29, 31–50 (1991)
Steinberger, B. Plumes in a convecting mantle: models and observations for individual hotspots. J. Geophys. Res. 105, 11127–11152 (2000)
Courtillot, V., Davaille, A., Besse, J. & Stock, J. Three distinct types of hotspots in the Earth’s mantle. Earth Planet. Sci. Lett. 205, 295–308 (2003)
Campbell, I. H. & Griffiths, R. W. The changing nature of mantle hotspots through time: implications for the geochemical evolution of the mantle. J. Geol. 100, 497–523 (1992)
Wellman, P. & McDougall, I. Cainozoic igneous activity in eastern Australia. Tectonophys. 23, 49–65 (1974)
Johnson, R. W. (ed.) Intraplate Volcanism in Eastern Australia and New Zealand Ch. 1.1 (Cambridge Univ. Press, 1989)
Knesel, K. M., Cohen, B. E., Vasconcelos, P. M. & Thiede, D. S. Rapid change in drift of the Australian plate records collision with Ontong Java plateau. Nature 454, 754–757 (2008)
Sutherland, F. L., Graham, I. T., Meffre, S., Zwingmann, H. & Pogson, R. E. Passive-margin prolonged volcanism, east Australian plate: outbursts, progressions, plate controls and suggested causes. Aust. J. Earth Sci. 59, 983–1005 (2012)
Davies, D. R. & Rawlinson, N. On the origin of recent intra-plate volcanism in Australia. Geology 42, 1031–1034 (2014)
King, S. D. & Anderson, D. L. Edge-driven convection. Earth Planet. Sci. Lett. 160, 289–296 (1998)
Ewart, A., Chappell, B. W. & Menzies, M. A. An overview of the geochemical and isotopic characteristics of the eastern Australian Cainozoic volcanic provinces. J. Petrol. 1, 225–273 (1988)
Torsvik, T. H., Steinberger, B., Gurnis, M. & Gaina, C. Plate tectonics and net lithosphere rotation over the past 150 Myr. Earth Planet. Sci. Lett. 291, 106–112 (2010)
Leitch, A. M. & Davies, G. F. Mantle plumes and flood basalts: enhanced melting from plume ascent and an eclogite component. J. Geophys. Res. 106, 2047–2059 (2001)
Tarduno, J. A. et al. The Emperor Seamounts: southward motion of the Hawaiian hotspot plume in Earth’s mantle. Science 301, 1064–1069 (2003)
Davies, D. R. & Davies, J. H. Thermally-driven mantle plumes reconcile multiple hotspot observations. Earth Planet. Sci. Lett. 278, 50–54 (2009)
Sleep, N. H. Lateral flow of hot plume material ponded at sublithospheric depths. J. Geophys. Res. 101, 28065–28083 (1996)
Rawlinson, N., Kennett, B. L. N., Salmon, M. & Glen, R. A. in The Earth’s Heterogeneous Mantle: A Geophysical, Geodynamical, and Geochemical Perspective Ch. 2 (eds Khan, A., & Deschamps, F. ) 47–78 (Springer, 2015)
Kennett, B. L. N., Fichtner, A., Fishwick, S. & Yoshizawa, K. Australian Seismological Reference Model (AuSREM): mantle component. Geophys. J. Int. 192, 871–887 (2013)
Farrington, R. J., Stegman, D. R., Moresi, L. N., Sandiford, M. & May, D. A. Interactions of 3D mantle flow and continental lithosphere near passive margins. Tectonophys. 483, 20–28 (2010)
Paul, B., Hergt, J. M. & Woodhead, J. D. Mantle heterogeneity beneath the Cenozoic volcanic provinces of central Victoria inferred from trace-element and Sr, Nd, Pb and Hf isotope data. Aust. J. Earth Sci. 52, 243–260 (2005)
Hofmann, A. W. in Treatise on Geochemistry Vol. 2 (ed. Carlson, R. W. ) 61–101 (Elsevier, 2003)
Ringwood, A. E. Composition and Petrology of the Earth’s Mantle (McGraw-Hill, 1975)
Rawlinson, N. et al. Complex continental growth along the proto-Pacific margin of East Gondwana. Geology 42, 783–786 (2014)
Montelli, R., Nolet, G., Dahlen, F. A. & Masters, G. A catalogue of deep mantle plumes: new results from finite-frequency tomography. Geochem. Geophys. Geosys. 7, Q11007 (2006)
McDonough, W. F. & Sun, S.-S. The composition of the Earth. Chem. Geol. 120, 223–253 (1995)
Antretter, M., Steinberger, B., Heider, F. & Soffel, H. Paleolatitudes of the Kerguelen hotspot: new paleomagnetic results and dynamic modelling. Earth Planet. Sci. Lett. 203, 635–650 (2002)
Tarduno, J. A., Bunge, H.-P., Sleep, N. & Hansen, U. The bent Hawaiian-Emperor hotspot track: inheriting the mantle wind. Science 324, 50–53 (2009)
Rawlinson, N. & Urvoy, M. Simultaneous inversion of active and passive source datasets for 3-D seismic structure with application to Tasmania. Geophys. Res. Lett. 33, L24313 (2006)
Rawlinson, N., Tkalcic, H. & Reading, A. M. Structure of the Tasmanian lithosphere from 3D seismic tomography. Aust. J. Earth Sci. 57, 381–394 (2010)
Rawlinson, N., Salmon, M. & Kennett, B. L. N. Transportable seismic array tomography in southeast Australia: illuminating the transition from Proterozoic to Phanerozoic lithosphere. Lithos 189, 65–76 (2014)
Simons, F. J. & van der Hilst, R. D. Age-dependent seismic thickness and mechanical strength of the Australian lithosphere. Geophys. Res. Lett. 29, 1529 (2002)
Fishwick, S. & Rawlinson, N. 3-D structure of the Australian lithosphere from evolving seismic datasets. Aust. J. Earth Sci. 59, 809–826 (2012)
Yoshizawa, K. Radially anisotropic 3-D shear wave structure of the Australian lithosphere and asthenosphere from multi-mode surface waves. Phys. Earth Planet. Inter. 235, 33–48 (2014)
Fishwick, S., Heintz, M., Kennett, B. L. N., Reading, A. M. & Yoshizawa, K. Steps in lithospheric thickness within eastern Australia: evidence from surface wave tomography. Tectonics 27, TC4009 (2008)
Kennett, B. L. N. & Salmon, M. AuSREM: Australian seismological reference model. Aust. J. Earth Sci. 59, 1091–1103 (2012)
Nelson, D. R., McCulloch, M. T. & Sun, S.-S. The origins of ultrapotassic rocks as inferred from Sr, Nd, and Pb isotopes. Geochim. Cosmochim. Acta 50, 231–245 (1986)
D.R.D. is funded by an Australian Research Council Future Fellowship (FT140101262). G.I. acknowledges support from the Ringwood Fellowship at the Australian National University. Digital geological data were provided by Geosciences Australia.
The authors declare no competing financial interests.
Extended data figures and tables
Extended Data Figure 1 Locations of the 15 volcanic centres used in our reconstruction of the Cosgrove hotspot track.
The hotspot track is indicated with a dashed line.
As in Fig. 1a but incorporating all 15 dated volcanic complexes and extended southwards to show the predicted present-day location of the underlying mantle plume (green square to the northwest of Tasmania). The approximate location of the East Australia Plume System, imaged previously using finite frequency tomography30, is marked by the dotted green line.
The number of predicted volcanic centre locations, from a total of 15 (listed in Extended Data Table 1), that fall within the uncertainty circles surrounding the dated volcanic centres, for a range of plume drift velocities and melt region diameters. Note that the reconstructions illustrated in Fig. 1a and Extended Data Fig. 2 assume a plume drift velocity of 1 cm yr−1 and a melt region diameter of 100 km (black square).
Extended Data Figure 4 Location of WOMBAT array stations used to create the three-dimensional P-wave velocity model from which our lithospheric thickness estimate was derived.
Station spacing is ∼50 km, which roughly equates to the maximum horizontal resolution of the three-dimensional velocity model.
North of ∼28° S, the model reverts to the AuSREM mantle model, owing to a lack of additional data coverage in this region (see Extended Data Fig. 4).
a, b, Lithosphere thickness model illustrated in Fig. 1b (a), alongside an estimate of its uncertainty (b), given by the standard deviation (σ) of an ensemble of 540 plausible models examined. Note that south of ∼28 °S, the lithospheric thickness estimate is constrained by high-resolution body-wave tomography (∼50 km horizontal resolution), whereas north of this latitude it is constrained entirely by the AuSREM mantle model (∼200–250 km horizontal resolution)24.
About this article
Cite this article
Davies, D., Rawlinson, N., Iaffaldano, G. et al. Lithospheric controls on magma composition along Earth’s longest continental hotspot track. Nature 525, 511–514 (2015). https://doi.org/10.1038/nature14903
The Lithospheric Thickness Control on the Compositional Variation of Continental Intraplate Basalts: A Demonstration Using the Cenozoic Basalts and Clinopyroxene Megacrysts From Eastern China
Journal of Geophysical Research: Solid Earth (2020)
New Zealand Journal of Geology and Geophysics (2020)
Basalt lava flows of the intraplate Newer Volcanic Province in south-east Australia (Melbourne region): 40Ar/39Ar geochronology reveals ~8 Ma of episodic activity
Journal of Volcanology and Geothermal Research (2020)
Lithospheric architecture of a Phanerozoic orogen from magnetotellurics: AusLAMP in the Tasmanides, southeast Australia