Upwelling Mantle Plume Research Articles

Seismic tomographic evidence for upwelling mantle plume in NE China

In this study, we collected teleseismic data recorded by permanent and mobile seismic stations and carried out a teleseismic P-wave tomographic study. The results reveal low velocity perturbation regions at the central part of NE China and specifically in the Songliao basin at different depths, which correspond to the location of a proposed upwelling mantle plume identified by receiver function in a recent study. Receiver function data show a predominantly mafic/ultra-mafic lower crust in the Songliao basin, in contrast to the predominantly felsic lower crust in the other regions. The vestige of upwelling mantle plume is well defined at the mantle transition region. Based on the above results, we suggest that the volcanism in NE China and the Songliao basin formation might be related to Mesozoic mantle plume beneath NE China. We also evaluate alternate models on lower crustal delamination contributing to the volcanism in NE China following collision and amalgamation between the Siberia craton and the North China–Mongolian block during late Jurassic and early Cretaceous.

Plume‐orogenic lithosphere interaction recorded in the Haladala layered intrusion in the Southwest Tianshan Orogen, NW China

AbstractThe plume‐orogenic lithosphere interaction may be common and important for the generation of large igneous provinces. The information regarding such a process is recorded by the Haladala gabbroic intrusion (~300 Ma), the largest layered ultramafic‐mafic intrusion hosting V‐Ti magnetite deposits in the Southwest Tianshan Orogen, NW China. The Haladala gabbros exhibit unfractionated chondrite‐normalized rare earth element patterns with negative Nb and Ta anomalies and positive Pb anomaly on the primitive mantle‐normalized multielement variation diagram. They are characterized by low initial Sr isotopes, slightly decoupled but high positive bulk rock εNd(t) and εHf(t), and high 207Pb/204Pb and 208Pb/204Pb relative to 206Pb/204Pb, delineating a DUPAL signature in the sources. The Haladala gabbros cannot be arc or postcollisional magmatism, given the lack of hydrous minerals and low K contents, respectively. This is further supported by the relatively low oxygen fugacity required for the gradual enrichment of V‐Ti magnetite during the magma fractionation and by an overall anhydrous mantle source suggested by troctolite mineral assemblage (olivine + plagioclase). The emplacement age of the Haladala gabbros is identical to that of the Wajilitag kimberlites in the Tarim's interior, which have been interpreted as the first magmatic expression of the Tarim mantle plume. We thus propose that the Haladala gabbroic intrusion was generated in a hybrid geodynamic setting in which the Southwest Tianshan Orogen was impacted by an upwelling mantle plume. In this sense, the Haladala layered gabbroic intrusion records the early phase of magmatism of the Tarim plume, which was preferentially emplaced in a lithospheric weak zone.

Crustal and uppermost mantle structure variation beneath La Réunion hotspot track

The Piton de la Fournaise basaltic volcano, on La Reunion Island in the western Indian Ocean, is one of the most active volcanoes in the world. This volcano is classically considered as the surface expression of an upwelling mantle plume and its activity is continuously monitored, providing detailed information on its superficial dynamics and on the edifice structure. Deeper crustal and upper mantle structure under La Reunion Island is surprisingly poorly constrained, motivating this study. We used receiver function techniques to determine a shear wave velocity profile through the crust and uppermost mantle beneath La Reunion , but also at other seismic stations located on the hotspot track, to investigate the plume and lithosphere interaction and its evolution through time. Receiver functions (RFs) were computed at permanent broad-band seismic stations from the GEOSCOPE network (on La Reunion and Rodrigues), at IRIS stations MRIV and DGAR installed on Mauritius and Diego Garcia islands, and at the GEOFON stations KAAM and HMDM on the Maldives. We performed non-linear inversions of RFs through modelling of P-to-S conversions at various crustal and upper mantle interfaces. Joint inversion of RF and surface wave dispersion data suggests a much deeper Mohorovici´iscontinuity (Moho) beneath Mauritius (∼21 km) compared to La Reunion (∼12 km). A magmatic underplated body may be present under La Reunion as a thin layer (≤3 km thick), as suggested by a previous seismic refraction study, and as a much thicker layer beneath other stations located on the hotspot track, suggesting that underplating is an important process resulting from the plume–lithosphere interaction. We find evidence for a strikingly low velocity layer starting at about 33 km depth beneath La Reunion that we interpret as a zone of partial melt beneath the active volcano. We finally observe low velocities below 70 km beneath La Reunion and below 50 km beneath Mauritius that could represent the base of the oceanic lithosphere.

Geochemistry and petrogenesis of mafic–ultramafic suites of the Irindina Province, Northern Territory, Australia: Implications for the Neoproterozoic to Devonian evolution of central Australia

Petrological and geochemical data for magmatic mafic–ultramafic suites of the Irindina and Aileron provinces of the Eastern Arunta region, Northern Territory, Australia constrain the petrogenesis and tectonic setting of magmatic events covering ~500millionyears. Six geochemically distinct magmatic suites, here named A–F, have been identified and provide evidence of the tectonic history of this region and also are linked to two mineralisation-related magmatic events: the Lloyd Gabbro (Ni–Cu–PGE mineralisation) and the Riddoch Amphibolite (Cyprus-style Cu–Co volcanogenic massive sulphide mineralisation).The whole-rock geochemistry of Suites A and F is indicative of melts derived from a range of mantle depths (garnet to spinel lherzolite) and source enrichment. Suite D is likely related to the ~1070Ma Warakurna/Giles event of central Australia, including the Alcurra (Musgrave) and Stuart (Arunta) dyke swarms, and likely formed through either: a) melting of subduction modified, sub-continental lithospheric mantle (SCLM) by an upwelling mantle plume; or b) a combination of intra-plate tectonic processes involving a long-lived thermal anomaly, lithospheric-scale architecture that focussed magmatism, and large-scale tectonism. Suite F represents more alkaline magmas, derived from a deeper source, but most likely formed during the same Warakurna LIP event (possibly contemporaneously) as Suite D. Suite E (the Riddoch Amphibolite) was most likely emplaced in a back-arc basin (BAB) setting at ~600Ma, coincident with Delamerian subduction and BAB formation along the eastern Proterozoic margin of Australia from Queensland to the eastern Arunta and possibly further south. Subsequent destabilisation of the SCLM underneath the North Australian Craton generated the ~510Ma Kalkarindji LIP in the form of Suite B intrusions that assimilated some of the older Suite E (Riddoch) material. This event is locally known as the ~506Ma Stanovos Igneous Suite and represents the most voluminous magmatic event within the study area. Suite A samples are more alkaline and cannot be correlated with any known magmatic events; however, they probably represent an unidentified alkaline phase of the Kalkarindji LIP event derived from a deep mantle source region. This suite is similar to the more widespread Kalkarindji and Suite B/Stanovos magmas in that these magmas assimilated arc material (i.e., Suite D) prior to emplacement. The last magmatic event occurred during the exhumation and inversion of the Irindina basin during the 450–300Ma Alice Springs Orogeny, resulting in the formation of melts derived from a deep mantle source. These melts subsequently became contaminated en route to emplacement as the ~409Ma Suite C Lloyd Gabbro.

Thermal evolution of Venus with argon degassing

Decades-old measurements of atmospheric and elemental surface composition constrain the history of Venus. In this study, we search for a model featuring continuous evolution in the stagnant-lid regime that predicts the present-day atmospheric mass of radiogenic argon and satisfies the other available constraints. For comparison, we also consider the end-member scenario of a single catastrophic resurfacing event. Thermal evolution simulations are performed that track the mass transport of argon and potassium and include a simple model of upwelling mantle plumes. Sensitivity analyses and linear regression are used to quantify the range of initial conditions that will produce desired values for key model output parameters. Decompression melting of passively upwelling mantle causes considerable mantle processing and crustal growth during the early evolution of Venus. Mantle plumes have negligible effects on recent crustal production, but may be important to local surface features. For a wide range of initial conditions, continuous evolution in the stagnant-lid regime predicts the correct amount of argon degassing, along with the absence of a global magnetic field, crustal and lithosphere thicknesses matching modern estimates, and volcanism consistent with the cratering record. Argon degassing does not uniquely constrain mantle dynamics, but the success of simple stagnant-lid models diminishes the need to invoke dramatic changes like catastrophic resurfacing.

On the origin of recent intraplate volcanism in Australia

Many intraplate volcanic provinces do not appear to originate from plate-boundary processes or upwelling mantle plumes. Edge-driven convection (EDC), where a small-scale convective instability (induced by local variations in lithospheric thickness) displaces hot mantle material upward, provides an alternative hypothesis for such volcanism. Recently, EDC has been postulated as the trigger for Quaternary intraplate volcanism in Australia, due to the proximity of a craton edge. However, the Precambrian shield region of the Australian continent has a boundary that is at least 10,000 km long, yet the Newer Volcanics Province (NVP) is contained within a 400 × 100 km region. This brings into question EDC as a causal mechanism, unless nucleation at a single location can be explained. Here, we use a combination of seismic tomography and geodynamic modeling to show, for the first time, that (1) the source of the NVP is restricted to the upper mantle, and (2) mantle upwelling triggered by EDC is localized and intensified beneath the NVP as a result of three-dimensional variations in lithospheric thickness and plate motion–induced shear flow. This study helps to solve the global puzzle of why step changes in lithospheric thickness, which occur along craton edges and at passive margins, produce volcanism only at isolated locations.

North Atlantic magmatism controlled by temperature, mantle composition and buoyancy

Compositional variations in the mantle can generate anomalous magmatism, calling into question the need for hot, upwelling mantle plumes. Numerical simulations, however, point to a plume source for the North Atlantic large igneous province.

Intracontinental anorogenic alkaline magmatism and carbonatites, associated mineral systems and the mantle plume connection

Intracontinental alkaline complexes and carbonatites commonly occur in rift-related settings, best exemplified by the Cenozoic–present day East African Rift System. Examples in the ancient geological record are more difficult to unravel due to subsequent overprinting during tectono-thermal events unrelated to the original rifting. In the present paper, with the exception of the Bayan Obo carbonatite, I have used examples of anorogenic alkaline complexes and carbonatites that are effectively pristine and unaffected or little influenced by later geological events. In this context, I report on two alkaline complexes and associated mineralisation in Namibia (Brandberg and Erongo) related to the opening of the South Atlantic and the Paraná–Etendeka large igneous province. With regard to carbonatites and associated mineralisation, I discuss the exceptionally well-preserved Kruidfontein and Goudini in South Africa, Mount Weld and Gifford Creek ferrocarbonatite complex in Western Australia, the controversial Bayan Obo in northern China and the carbonatites of the Mianning–Dechang belt in SW China. It is proposed that all these igneous systems are formed by processes of partial melting in metasomatised lithospheric mantle, induced by upwelling mantle plumes. Furthermore, it is contended that these alkaline and carbonatite igneous systems are generally formed in the distal sectors of a mantle plume due to lateral transfer of volatiles, resulting in low degrees of partial melting in the metasomatised sub-continental lithospheric mantle.

Helium and lead isotopes reveal the geochemical geometry of the Samoan plume.

Hotspot lavas erupted at ocean islands exhibit tremendous isotopic variability, indicating that there are numerous mantle components hosted in upwelling mantle plumes that generate volcanism at hotspots like Hawaii and Samoa. However, it is not known how the surface expression of the various geochemical components observed in hotspot volcanoes relates to their spatial distribution within the plume. Here we present a relationship between He and Pb isotopes in Samoan lavas that places severe constraints on the distribution of geochemical species within the plume. The Pb-isotopic compositions of the Samoan lavas reveal several distinct geochemical groups, each corresponding to a different geographic lineament of volcanoes. Each group has a signature associated with one of four mantle endmembers with low (3)He/(4)He: EMII (enriched mantle 2), EMI (enriched mantle 1), HIMU (high µ = (238)U/(204)Pb) and DM (depleted mantle). Critically, these four geochemical groups trend towards a common region of Pb-isotopic space with high (3)He/(4)He. This observation is consistent with several low-(3)He/(4)He components in the plume mixing with a common high-(3)He/(4)He component, but not mixing much with each other. The mixing relationships inferred from the new He and Pb isotopic data provide the clearest picture yet of the geochemical geometry of a mantle plume, and are best explained by a high-(3)He/(4)He plume matrix that hosts, and mixes with, several distinct low-(3)He/(4)He components.

Restoration of geometry and emplacement mode of the Permian mafic dyke swarms in Keping and its adjacent areas of the Tarim Block, NW China

Abstract The Permian mafic dyke swarms are widely distributed in the Tarim Block, East Tianshan and the western Junggar Block in northwestern China. These mafic dyke swarms, together with coeval basalts, mafic–ultramafic intrusions and A-type granitic plutons, constitute the Permian Tarim large igneous province (LIP), which is considered to be mantle plume-derived. In this study, multi-source high-resolution remote sensing images are used to identify the geometry and emplacement mode of the mafic dykes, sills and flood basalts in Keping and its adjacent areas including Bachu (northwestern Tarim Block), Beishan and Kuluketag (northeastern Tarim Block) and Kelamyi (western Junggar Block). Structural analysis and paleomagnetic results are used to restore the primary geometry of the mafic dykes. The results indicate that the lengths and thicknesses among a total of 117 extracted mafic dykes in Keping follow negative exponent size distributions. The mafic dykes have a mean thickness of 3.8 m with a maximum of 21.4 m. The length of unconnected mafic dyke segments ranges from 0.127 km to 17.1 km, with an arithmetic length of 1.8 km. The restoration of geometry of the mafic dykes indicates that the Permian mafic dyke swarms in Keping may have extended as far as 61–69 km along a primary orientation of about N320°W, and the flood basalts of the Tarim LIP may have extended to Keping so that the areal extent of the Tarim LIP could be enlarged for about 12,000 km 2 compared with that originally reported (about 250,000 km 2 ). The geometric features of the mafic dyke swarms in Keping and its adjacent areas are different from those of the giant radiating dyke swarms due to radial fractures associated with domal uplift. The mafic dyke swarms and sills in the Tarim LIP make up the plumbing system of the mantle plume. Accompanied by the upwelling of mantle plume, many eruptive centers and regional dykes are generated in Beishan, East Tianshan and Tarim basin. The flood basalts in Keping are fissure-type, which may have been fed by magma conduits from the plume center; whereas in Bachu, the central volcanic eruption is dominant.

Interactions between continent-like ‘drift’, rifting and mantle flow on Venus: gravity interpretations and Earth analogues

Abstract Regional shear zones are interpreted from Bouguer gravity data over northern polar to low southern latitudes of Venus. Offset and deflection of horizontal gravity gradient edges (‘worms’) and lineaments interpreted from displacement of Bouguer anomalies portray crustal structures, the geometry of which resembles both regional transcurrent shear zones bounding or cross-cutting cratons and fracture zones in oceanic crust on Earth. High Bouguer anomalies and thinned crust comparable to the Mid-Continent Rift in North America suggest underplating of denser, mantle-derived mafic material beneath extended crust in Sedna and Guinevere planitia on Venus. These rifts are partitioned by transfer faults and flank a zone of mantle upwelling (Eistla Regio) between colinear hot, upwelling mantle plumes. Data support the northward drift and indentation of Lakshmi Planum in western Ishtar Terra and >1000 km of transcurrent displacement between Ovda and Thetis regiones. Large displacements of areas of continent-like crust on Venus are interpreted to result from mantle tractions and pressure acting against their deep lithospheric mantle ‘keels’ commensurate with extension in adjacent rifts. Displacements of Lakshmi Planum and Ovda and Thetis regiones on Venus, a planet without plate tectonics, cannot be attributed to plate boundary forces (i.e. ridge push and slab pull). Results therefore suggest that a similar, subduction-free geodynamic model may explain deformation features in Archaean greenstone terrains on Earth. Continent-like ‘drift’ on Venus also resembles models for the late Cenozoic–Recent Earth, where westward translation of the Americas and northward displacement of India are interpreted as being driven by mantle flow tractions on the keels of their Precambrian cratons. Supplementary material: Bouguer gravity and topographic images over a segment of the Mid-Atlantic ridge and Ross Island and surrounds in Antarctica, principal horizontal stress trajectories about mantle plumes on Earth, map and interactive 3D representations of cratonic keels beneath North America from seismic tomography, and a centrifuge simulation for comparison with Venus in support of our tectonic model are available at http://www.geolsoc.org.uk/SUP18736 .

Plume or no plume: Emeishan Large Igneous Province in Southwest China revisited from receiver function analysis

The Late Permian Emeishan Large Igneous Province at the western margin of the Yangtze craton and eastern Tibet is popularly regarded as the signature of mantle plume impingement onto the lithosphere. In this study, we investigate the crustal structure and upper mantle discontinuities of this region by employing H–k stacking of receiver function and depth domain receiver function. Our results image the mantle transition zone. However, no vestiges of any mantle plume upwelling in this area are recorded in our results, and the region is characterized by a largely cold domain. In contrast, our data reveal a region of lower crustal delamination that coincides with the cold mantle transition zone. We therefore suggest that the delaminated lower crustal material was recycled into the upper mantle or the mantle transition zone, turning the latter into a cold domain. The delamination of the lower crust might have also led to asthenospheric upwelling and plume-like upwelling from the mantle transition zone that generated the basalts in the Emeishan Large Igneous Province.

The Early Permian Tarim Large Igneous Province: Main characteristics and a plume incubation model

The Early Permian magmatism in Tarim, NW China comprises diamondiferous kimberlites, lamprophyres, flood basalts, Fe–Ti oxide ore-bearing layered mafic–ultramafic intrusions, bi-modal dyke swarms, alkaline igneous complexes (including syenites and A-type granites), rhyolites and pyroclastic rocks. The extent of this intraplate magmatism exceeds 250,000 km 2 , making it comparable to Large Igneous Provinces (LIPs). Screening of available radiometric ages reveals three main magmatic episodes in the Tarim LIP, with the first being marked by ~ 300 Ma small-volume kimberlites, followed by two phases of bimodal magmatism at ~ 290 Ma and at ~ 280 Ma, respectively. This relatively long time interval of the Early Permian magmatism is consistent with a low eruption rate of the Tarim LIP and is supported by the intercalation of volcanic rocks with sediments in outcrops and drill holes. Although the spatial distribution of each magmatic episode in the Tarim LIP is far from assessed, it seems that the ~ 290 Ma flood basalts are widespread across the province, whereas ~ 300 Ma kimberlites and ~ 280 Ma ultramafic–mafic–felsic intrusions and dyke swarms only occur in the Bachu Uplift and around the margins of the Tarim craton. We propose that the ~ 300 Ma kimberlites were derived from deep part of the metasomatized sub-continental lithospheric mantle (SCLM), while the ~ 290 Ma flood basalts were likely formed as a result of mixing of plume-derived melts with SCLM-derived melts (e.g., lamproitic melt) as they rose through the SCLM. In contrast, the ~ 280 Ma magmas were most likely derived from the convecting mantle. A plume incubation model is proposed to account for the temporo-spatial distribution of the Tarim LIP, in which different styles of plume–lithosphere interaction are recognized. In the first two episodes, the mantle plume incubating the base of the craton provides the heat that triggered melting of the enriched components in the SCLM. In contrast, adiabatic decompression melting within the plume produced the ~ 280 Ma magmatic phase. Thermal modeling suggests that lithospheric thinning by thermal erosion might have been associated with the upwelling mantle plume, with the greatest thinning occurring in the Bachu area. Thinned spots and weak zones at the margins of cratons and mobile belts caused preferential channeling of plume flow and subsequent decompression melting. This explains the localized distribution of ~ 280 Ma magmas in the Tarim LIP. • Spatial distribution of igneous rocks in the Tarim large igneous province • Three magmatic episodes possess distinct rock association and geochemistry. • Lithospheric thinning in association with thermal erosion by upwelling mantle • Plume–lithosphere interaction in the formation of the Tarim LIP

Mantle flow and multistage melting beneath the Galápagos hotspot revealed by seismic imaging

Upwelling mantle plumes are thought to be sheared by the motions of the overlying tectonic plates. Seismic imaging of a hotspot beneath the Galapagos Islands, however, identifies a plume that is not deflected in the direction of plate motion and whose characteristics are instead controlled by multistage melting processes.

Seismic anisotropy surrounding South China Sea and its geodynamic implications

Several mechanisms have been proposed for the opening of the South China Sea. Here, we use SKS splitting analysis to investigate the mantle flow surrounding the South China Sea. We use a total of 23 seismic stations and 87 events. We applied spectral analysis and cluster analysis to find a stable splitting solution for each event. The main conclusions are: (1) In northern Vietnam, the NW–SE fast direction is parallel to the absolute plate motion as well as GPS observations with splitting times larger than 1 s, indicating a coupled lithosphere and mantle. In contrast, in southern Vietnam, the NE–SW fast direction suggests that the lithosphere and asthenosphere are decoupled. (2) The fast directions beneath the South China Block and central Taiwan are NE–SW and NS respectively, both parallel to surface deformations with splitting times greater than 1 s, indicating that mantle flow and surface deformation are related. (3) The observed NW–SE fast directions beneath Hainan Island reflect the India–Eurasia collision, and show no signatures of an upwelling mantle plume directly underneath Hainan Island. This implies that Hainan Island is tectonically closely related to the Red River Fault, not the South China Block. (4) In Borneo, the observed NE-SW direction is parallel to the Palawan Trench, consistent with flow associated with the inactive proto-South China Sea subduction system. The SKS splitting observations surrounding South China Sea cannot be explained by a single geologic process, with either the collision-driven extrusion model or the slab pull model fitting the data presented here.

Hidden hotspot track beneath the eastern United States

Hotspot tracks are thought to be the surface expressions of tectonic plates moving over upwelling mantle plumes, and are characterized by volcanic activity that is age progressive. At present, most hotspot tracks are observed on oceanic or thin continental lithosphere. For old, thick continental lithosphere, such as the eastern United States, hotspot tracks are mainly inferred from sporadic diamondiferous kimberlites putatively sourced from the deep mantle. Here we use seismic waveforms initiated by the 2011 M_w 5.6 Virginia earthquake, recorded by the seismic observation network USArray, to analyse the structure of the continental lithosphere in the eastern United States. We identify an unexpected linear seismic anomaly in the lower lithosphere that has both a reduced P-wave velocity and high attenuation, and which we interpret as a hotspot track. The anomaly extends eastwards, from Missouri to Virginia, cross-cutting the New Madrid rift system, and then bends northwards. It has no clear relationship with the surface geology, but crosses a 75-million-year-old kimberlite in Kentucky. We use geodynamical modelling to show that an upwelling thermal mantle plume that interacts with the base of continental lithosphere can produce the observed seismic anomaly. We suggest that the hotspot track could be responsible for late Mesozoic reactivation of the New Madrid rift system and seismicity of the eastern United States.

Seismic evidence for plume-induced rifting in the Songliao Basin of Northeast China

Abstract The concept of Pacific slab subduction has been advocated in many popular models as the main cause for lithospheric delamination in the eastern part of the North China Craton since Mesozoic. This process is considered to have induced extensional tectonics generating the Songliao Basin and widespread magma intrusion and eruption. In this paper, we used H-κ and CCP (common-conversion-point) stacking technique of receiver function to characterize the crustal structure and upper mantle discontinuities in this region. Seismic evidence from our results present a different perspective suggesting mantle plume, continental rifting process and magmatic underplating in this region. A projection of the proposed plume onto the surface overlaps with the locations of the lithosphere and crustal thinning as well as the mafic–ultramafic domains. We therefore propose that an upwelling mantle plume and related extension might have been the main trigger for the formation of the Mesozoic Songliao Basin in NE China.

Topography of the lithosphere–asthenosphere boundary below the Upper Rhine Graben Rift and the volcanic Eifel region, Central Europe

We study the crust–mantle and lithosphere–asthenosphere boundaries (Moho and LAB) in Central Europe, specifically below the Upper Rhine Graben (URG) rift, the Eifel volcanic region and their surrounding areas. Teleseismic recordings at permanent and mobile stations are analysed to search for shear ( S ) wave to compressional ( P ) wave converted phases. After a special processing these phases are identified in shear wave receiver functions ( S -RFs). Conversions from the Moho at 2.9–3.3 s arrival time are the clearest signals in the S -RFs and indicate a relatively flat Moho at 27–30 km depth. A negative polarity conversion signal at 7–9 s arrival time can be explained with a low shear wave velocity zone (LVsZ) in the upper mantle. We use forward S -RF waveform modelling and Monte-Carlo techniques to determine shear wave velocity ( vs )–depth ( z ) profiles which explain the observed S -RF and which outline variations of the lithospheric thickness in the study region. Across the URG rift and its surrounding mountain ranges (Black Forest, Odenwald etc.) the LAB is at a depth of about 60 ± 5 km. This depth is found for the rift itself as well as for the rift shoulders. Southeast and southwest of the URG, in the regions of the Swabian Alb and Vosges Mountains, the LAB dips to about 78 ± 5 km depth. In the volcanic Eifel region the LAB is at a much shallower depth of just 41 ± 5 km. There an upwelling mantle plume thermally eroded the lower lithosphere. The reduction of vs is about 2%–4% in the upper asthenosphere compared to the lower lithosphere. This vs contrast may be explained with a low portion of partial melt or hydrous minerals in the asthenosphere. • Densely spaced S -wave receiver functions are determined. • Waveform modelling provides constraints of a low velocity mantle layer (LAB). • LAB topography varies significantly in the study region. • Lithosphere thickness is only about 41 km above the Eifel plume. • Lithosphere thickness is about 60 km in the Upper Rhine Graben and at its flanks.

Bifurcation of the Yellowstone plume driven by subduction-induced mantle flow

In the northwestern United States, two neighbouring volcanic chains—the Snake River Plain and High Lava Plains—decrease in age in opposing directions. Laboratory experiments show that diverging volcanic chains can form where vigorous mantle circulation beneath a subduction zone causes an upwelling mantle plume to split into two.

Relative importance of different physical processes on upper crustal specific heat flow in the Eifel-Maas region, Central Europe and ramifications for the production of geothermal energy

We study the recent upper crustal heat flow variations caused by long-term physical processes such as paleoclimate, erosion, sedimentation and mantle plume upwelling. As specific heat flow is a common lower boundary condition in many models of heat en fluid flow in the Earth’s crust we quantify its long-term transient variation caused by paleoclimate, erosion or sedimentation, mantle plume upwelling and deep groundwater flow. The studied area extends between the Eifel mountains and the Maas river inCentral Europe. The total variation due to these processes in our study area amounts to tectonic events manifested in the studied area 20 mW/m2, about 30% of the present day specific heat flow in the region.