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Satellite bathymetry map of the western Indian Ocean basin. Approximate aerial extent of Deccan Traps lava flows are shown by the gray fields on the Indian subcontinent. Numbers in the shaded region correspond to sampling regions: 1-Kutch (samples 1-5), 2-Saurashtra (samples 6-46), 3-Pavagadh, Kalsubai, Amba Dongar and surrounds (samples 48-54, 63-78), 4-Dhule and surrounds (samples 55-62), 5-Mumbai, Western Ghats and coastal Maharashtra (samples 79-115, MMF7). Approximate trace of the Réunion hotspot is shown by the transparent black arrow, approximate plate motion vectors are shown by solid black arrows over land areas and are proportional to plate motions. Base map reproduced from the GEBCO world map 2014, www.gebco.net.
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![Figure 2 (a) 187 Os/ 188 Os versus [Os] for Deccan lavas (red circles),...](profile/James-Day-13/publication/320835153/figure/fig2/AS:674896124342272@1537919183748/a-187-Os-188-Os-versus-Os-for-Deccan-lavas-red-circles-with-inferred-compositions_Q320.jpg)
Geodynamical models of mantle plumes often invoke initial, high volume plume 'head' magmatism, followed by lower volume plume 'tails'. However, geochemical links between plume heads, represented by flood basalts such as the Deccan Traps, and plume tails, represented by ocean islands such as La Réunion, are ambiguous, challenging this classical view...
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... best studied examples of plume head and tail relationships along a linear, age-progressive volcanic track is the Deccan-Réunion hotspot. There, a volumetrically massive continental flood basalt (CFB) province, the Deccan Traps, is linked by aseismic, submarine ridges to ocean island basalts (OIB) that actively erupt on the island of La Réunion (Fig. 1). A genetic link between Deccan CFB and Réunion OIB, and for other similar hotspot tracks, has often been implicitly assumed by mantle plume theory and is demanded by recent geody- namical models (Glišovi´cGlišovi´c and Forte, 2017). Such assumptions, however, are at odds with expected physical consequences of ancient mantle plumes; for ...
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... elemental and isotopic characteristics of Deccan Traps continental flood basalts (CFB) and determine their relationship to Réunion ocean island basalts (OIB). Sampling was performed throughout the western extent of the Deccan Traps, from northern expo- sures in the Kutch region of Gujarat, to southern exposures near Mahabaleshwar in Maharashtra ( Fig. S-1). These areas cover much of the chemostratigaphy of the Deccan Traps ( Fig. S-2), with the exception of the uppermost Desur and Panhala Formations, and possibly also the lowermost Jawhar Forma- tion. The availability of published maps identifying the surfi- cial extent of chemostratigraphic units, particularly far from the "main ...
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... Perspectives Letters Letter 2012; and likely results from sulphide satura- tion in evolved melts, causing rapid loss of IPGE to sulphide phases and preferential retention of PPGE in residual melts (Jamais et al., 2008). This process can be traced on a plot of PPGE versus Cu (Fig. S-10a), where PPGE contents below a certain level indicated by sulphur accumulation (traced by Cu) indicates previous extraction of sulphides. Many of our samples lie above the qualitative line separating S-saturated and S-undersaturated melts ( Keays andLightfoot, 2007, 2010), but still overlap with the field of S-saturated West Greenland ...
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... magma composition by regressing Ir versus MgO data for mineral separates and determining concentrations of the remaining HSE using the HSE/Ir ratios of the olivine separates. We can then quantify the effects of sulphide extraction using the partitioning data of Jamais et al. (2008) and empirically determined partition coef- ficients of Day (2013) (Fig. S-10b) and this assumed parental melt HSE concentration. With an assumed tholeiitic parental magma MgO composition of 16 wt. %, we model extraction of an olivine-clinopyroxene-orthopyroxene-plagioclase assem- blage and assimilation of upper continental crust (Peucker-Ehrenbrink and Jahn, 2001;Nishimura, 2012). Concentrations of MgO are ...
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Strongly SiO2-undersaturated alkalic rocks (Mg# > 50, SiO2 ≤ 45 wt%, Na2O + K2O ≥ 3 wt%) occur in three early-stage (Sarnu-Dandali, Mundwara, Bhuj) and one late-stage (Murud-Janjira) rift-associated volcanic complexes in the Cretaceous-Paleogene Deccan Traps flood basalt province of India. Thermobarometry based on clinopyroxene-liquid equilibrium s...
Citations
... It is followed by a thin island chain to the south, formed by the eruption of the Reunion mantle plume. 50,51 The distinctive eruption behavior of the Hawaiian plume seems to contradict the mantle plume hypothesis, which ll The Innovation 4(2): 100404, March 13, 2023 predicts that the eruption rate of the plume tail should be significantly lower than that of the plume head. 1,13,52 It is important to note that the rapidly increasing eruption rate of the Hawaiian plume in the last few million years is due to the growth of the Loa trend, which became clearly discernable at $5 Ma (Figures 1 and 2). ...
The Hawaiian-Emperor seamount chain has shown two subparallel geographical and geochemical volcanic trends, Loa and Kea, since ∼5 Ma, for which numerous models have been proposed that usually involve a single mantle plume sampling different compositional sources of the deep or shallow mantle. However, both the dramatically increased eruption rate of the Hawaiian hotspot since ∼5 Ma and the nearly simultaneous southward bending of the Hawaiian chain remain unexplained. Here, we propose a plume-plume interaction model where the compositionally depleted Kea trend represents the original Hawaiian plume tail and the relatively enriched Loa trend represents an emerging plume head southeast of the Hawaiian plume tail. Geodynamic modeling further suggests that the interaction between the existing Hawaiian plume tail and the emerging Loa plume head is responsible for the southward bending of the Hawaiian chain. We show that the arrival of the new plume head also dramatically increases the eruption rate along the hotspot track. We suggest that this double-plume scenario may also represent an important mechanism for the formation of other hotspot tracks in the Pacific plate, likely reflecting a dynamic reorganization of the lowermost mantle. Public summary: Hawaiian hotspot track displays two subparallel isotopic trends since 5 Ma. This is coeval with increased eruption rate and southward bending of the track. These data support a new plume head emerging next to the old Hawaiian plume. Our double-plume model may represent a new mechanism for hotspot evolution.
... The concept of mantle plume was initially proposed by W. Jason Morgan in 1971 based on the observation of the Hawaii hot spots (Wilson, 1963) to explain the age-progressive chains of volcanic islands that stretch across the ocean basins (Morgan, 1971). A mantle plume is generally composed of a huge head and a narrow tail that is connected to the deep mantle (Campbell et al., 1989;Campbell & Griffiths, 1990, 1992Hill et al., 1992;Kent et al., 1996;Larson, 1991;Peters & Day, 2017). During the ascent of a mantle plume, the head would trap large amounts of mantle material to enlarge itself. ...
There are various explanations for how the Earth’s continents form, develop, and change but challenges remain in fully understanding the driving forces behind plate tectonics on our planet.
... The concept of mantle plume was initially proposed by W. Jason Morgan in 1971 based on the observation of the Hawaii hot spots (Wilson, 1963) to explain the age-progressive chains of volcanic islands that stretch across the ocean basins (Morgan, 1971). A mantle plume is generally composed of a huge head and a narrow tail that is connected to the deep mantle (Campbell et al., 1989;Campbell & Griffiths, 1990, 1992Hill et al., 1992;Kent et al., 1996;Larson, 1991;Peters & Day, 2017). During the ascent of a mantle plume, the head would trap large amounts of mantle material to enlarge itself. ...
The continental crust is unique to the Earth in the solar system, and controversies remain regarding its origin, accretion and reworking of continents. The plate tectonics theory has been significantly challenged in explaining the origin of Archean (especially pre-3.0 Ga) continents as they rarely preserve hallmarks of plate tectonics. In contrast, growing evidence emerges to support oceanic plateau models that better explain characteristics of Archean continents, including the bimodal volcanics and nearly coeval emplacement of tonalite-trondjhemite-granodiorite (TTG) rocks, presence of ∼1600°C komatiites and dominant dome structures, and lack of ultra-high-pressure rocks, paired metamorphic belts and ophiolites. On the other hand, the theory of plate tectonics has been successfully applied to interpret the accretion of continents along subduction zones since the late Archean (3.0–2.5 Ga). During subduction processes, the new mafic crust is generated at the base of continents through partial melting of mantle wedge with the addition of H2O-dominant fluids from subducted oceanic slabs and partial melting of the juvenile mafic crust results in the generation of new felsic crusts. This eventually leads to the outgrowth of continents. Subduction processes also cause softening, thinning, and recycling of continental lithosphere due to the vigorous infiltration of volatile-rich fluids and melts, especially along weak belts/layers, leading to widespread continental reworking and even craton destruction. Reworking of continents also occurs in continental interiors due to either plate boundary processes or plume-lithosphere interactions. The effects of plumes have proven to be less significant and cause lower degrees of lithospheric modification than subduction-induced craton destruction.
... The concept of mantle plume was initially proposed by W. Jason Morgan in 1971 based on the observation of the Hawaii hot spots (Wilson, 1963) to explain the age-progressive chains of volcanic islands that stretch across the ocean basins (Morgan, 1971). A mantle plume is generally composed of a huge head and a narrow tail that is connected to the deep mantle (Campbell et al., 1989;Campbell & Griffiths, 1990, 1992Hill et al., 1992;Kent et al., 1996;Larson, 1991;Peters & Day, 2017). During the ascent of a mantle plume, the head would trap large amounts of mantle material to enlarge itself. ...
... It has been suggested, based on unradiogenic He and Ne, that the source of these samples is deep, undegassed mantle (Breddam et al., 2000;Moreira et al., 2001). The remaining samples come from several ocean island localities in the Pacific, Indian and Atlantic ocean basins and have been previously characterized for major-and trace-elements, radiogenic isotopes, and Si and Ga stable isotopic compositions (LeRoex, 1985;Albarède and Tamagnan, 1988;Breddam et al., 2000;Claude-Ivanaj et al., 2001;Breddam, 2002;Workman et al., 2004;Geist et al., 2006;Jackson et al., 2007aJackson et al., , 2007bMillet et al., 2008;Kurz et al., 2009;Day et al., 2010;Kawabata et al., 2011;Hart and Jackson, 2014;Garapić et al., 2015, Pringle et al., 2016, Peters & Day, 2017Kato et al., 2017). ...
... g Puchtel et al. (2013). h Peters and Day (2017). ...
The radiogenic ⁸⁷Rb-⁸⁷Sr system has been widely applied to the study of geological and planetary processes. In contrast, the stable Sr isotopic composition of the bulk silicate Earth (BSE) and the effects of igneous differentiation on stable Sr isotopes are not well-established. Here we report the stable Sr isotope (⁸⁸Sr/⁸⁶Sr, reported as δ88/86Sr, in parts per mil relative to NIST SRM 987) compositions for ocean islands basalts (OIB), mid-ocean ridge basalts (MORB) and komatiites from a variety of locations. Stable Sr isotopes display limited fractionation in a OIB sample suite from the Kilauea Iki lava lake suggesting that igneous processes have limited effect on stable Sr isotope fractionation (±0.12‰ over 20% MgO variation; 2sd). In addition, OIB (δ88/86Sr = 0.16–0.46‰; average 0.28 ± 0.17‰), MORB (δ88/86Sr = 0.27–0.34‰; average 0.31 ± 0.05‰) and komatiites (δ88/86Sr = 0.20–0.97‰; average 0.41 ± 0.16‰) from global localities exhibit broadly similar Sr stable isotopic compositions. Heavy stable Sr isotope compositions (δ88/86Sr > 0.5‰) in some Barberton Greenstone belt komatiites may reflect Archean seawater alteration or metamorphic processes and preferential removal of the lighter isotopes of Sr. To first order, the similarity among OIBs from three different ocean basins suggests homogeneity of stable Sr isotopes in the mantle. Earth's mantle stable Sr isotopic composition is established from the data on OIB, MORB and komatiites to be δ88/86Sr = 0.30 ± 0.02‰ (2sd). The BSE δ88/86Sr value is identical, within uncertainties, to the composition of carbonaceous chondrites (δ88/86Sr = 0.29 ± 0.06‰; 2sd) measured in this study.
With a size of over 500,000 km2, the Deccan Volcanic Province (DVP) covers a large area of the Indian subcontinent. Stratigraphically continuous lava flows piled up to 3000 m record about five million years of volcanic activity. The peak activity of one million years coincides with the migration of the Indian subcontinent across the Réunion plume. Previous studies inferred an isotopic “common signature” for most DVP basalts that is best explained by a mixture of early Réunion plume-related melts and melts from the depleted upper mantle. Further chemical variability of the DVP sequence was explained by the incorporation of material from the lithospheric mantle and continental crust possibly within a single magma chamber system. Yet, indications for a complex crustal magmatic system have also been brought forward by earlier studies and find recently more support in explaining the magmatic plumbing system of the DVP and Large Igneous Provinces in general.
This study presents new major and trace element data, including high-precision concentration measurements of high-field strength elements by isotope dilution and Sr-Nd-Hf-Pb isotope compositions for basaltic samples that cover nearly the complete DVP main section. Based on significant variations in Nb/Th (and Th/Ta) over a wide range of MgO concentrations we identified three distinct magma differentiation trends. The distinct differentiation trends result from three types of parental melts that are best explained by different proportions of lower and upper mantle melts indicated by diluted Réunion plume-like trace element and isotope compositions that assimilated variable amounts of metasomatized lithospheric mantle and crustal material. Most likely the assimilation occurred before any major differentiation events, thus fixing the Nb/Th (and Th/Ta) of each group regardless of the degree of differentiation. The chemical trends can also be replicated using a statistical numerical approach, confirming that their geochemical signature truly reflects individual differentiation of three distinct parental melts. Field relations require that lavas related to these three unique differentiation trends erupted contemporaneously. This is in contrast to the idea of a gradually evolving single magma chamber system and the concept of a general chemostratigraphy for the DVP main plateau. Rather, our study reveals fast-changing contributions of different mantle reservoirs and provides new insight into the magma-plumbing systems of Large Igneous Provinces that may be more complex.
In peninsular India, the Deccan Traps record massive, continental-scale volcanism in a sequence of magmatic events that mark the mass extinction at the Cretaceous-Paleogene boundary. Although the Deccan volcanism is linked with the Réunion hotspot, the origin of its periodic magmatic pulses is still debated. We develop a numerical model, replicating the geodynamic scenario of the African superplume underneath a moving Indian plate, to explore the mechanism of magmatic pulse generation during the Deccan volcanism. Our model finds a connection between the Réunion hotspot and the African large low shear-wave velocity province (LLSVP) to show pulse generation from a thermochemical plume in the lower mantle. The plume is perturbed at 660 km, and its head eventually detaches from the tail under the influence of Indian plate movement to produce four major pulses (periodicity: 5 - 8 Ma), each giving rise to multiple secondary magmatic pulses at a time interval of ~ 0.15-0.4 Ma.
Thick and highly viscous roots are the key to cratonic survival. Nevertheless, cratonic roots can be destroyed under certain geological scenarios. Eruption of mantle plumes underneath cratons can reduce root viscosity and thus make them more prone to deformation by mantle convection. It has been proposed that the Indian craton could have been thinned due to eruption of the Réunion plume underneath it at ca. 65 Ma. In this study, we constructed spherical time-dependent forward mantle convection models to investigate whether the Réunion plume eruption could have reduced the Indian craton thickness. Along with testing the effect of different strengths of craton and its surrounding asthenosphere, we examined the effect of temperature-dependent viscosity on craton deformation. Our results show that the plume-induced thermomechanical erosion could have reduced the Indian craton thickness by as much as ~130 km in the presence of temperature-dependent viscosity. We also find that the plume material could have lubricated the lithosphere-asthenosphere boundary region beneath the Indian plate. This could be a potential reason for acceleration of the Indian plate since 65 Ma.
The Kerguelen large igneous province (LIP) has been related to mantle plume activity since at least 120 Ma. There are some older (147–130 Ma) magmatic provinces on circum-eastern Gondwana, but the relationship between these provinces and the Kerguelen mantle plume remains controversial. Here we present petrological, geochronological, geochemical, and Sr–Nd–Hf–Pb–Os isotopic data for high-Ti mafic rocks from two localities (Cuona and Jiangzi) in the eastern Tethyan Himalaya igneous province (147–130 Ma). Zircon grains from these two localities yielded concordant weighted mean 206Pb/238U ages of 137.25 ± 0.98 and 131.28 ± 0.78 Ma (2σ), respectively. The analyzed mafic rocks are enriched in high field strength elements and have positive Nb–Ta anomalies relative to Th and La, which have ocean island basalt-like characteristics. The Cuona basalts were generated by low degrees of melting (3–5%) of garnet lherzolites (3–5 vol.% garnet), and elsewhere the Jiangzi diabases were formed by relatively lower degrees of melting (1–3%) of garnet lherzolite (1–5 vol.% garnet). The highly radiogenic Os and Pb isotopic compositions of the Jiangzi diabases were produced by crustal contamination, but the Cuona basalts experienced the least crustal contamination given their relatively low γOs(t), 206Pb/204Pbi, 207Pb/204Pbi, and 208Pb/204Pbi values. Major and trace element geochemical and Sr–Nd–Hf–Pb–Os isotope data for the Cuona basalts are similar to products of the Kerguelen mantle plume head. Together with high mantle potential temperatures (>1500°C), this suggests that the eastern Tethyan Himalaya igneous province (147–130 Ma) was an early magmatic product of the Kerguelen plume. A mantle plume initiation model can explain the temporal and spatial evolution of the Kerguelen LIP, and pre-continental break-up played a role in the breakup of eastern Gondwana, given the >10 Myr between initial mantle plume activity (147–130 Ma) and continental break-up (132–130 Ma). Like studies of Re-Os isotopes in other LIPs, the increasing amount of crustal assimilation with distance from the plume stem can explain the variations in radiogenic Os.
The Steens Formation is one of the earliest and most primitive (>7 wt. MgO) eruptive products of the Columbia River Basalt Group (CRBG) and the CRBG-Yellowstone-Snake River large igneous province. New major-, trace-, and highly siderophile-element abundance and ⁸⁷Sr/⁸⁶Sr, ¹⁴³Nd/¹⁴⁴Nd and ¹⁸⁷Os/¹⁸⁸Os data are reported for the lower and upper Steens Formation to examine likely mantle sources and the nature of magmatic differentiation and crustal contamination acting on lavas. Examined Steens Formation basalts are relatively mafic (7–9 wt% MgO), incompatible trace element enriched, and have weaker Nb and Ta anomalies compared to other CRBG lavas. The most primitive basalts have isotopic compositions at the time of crystallization consistent with originating from a mantle source that was relatively depleted (⁸⁷Sr/⁸⁶Sr = ~0.7033; εNdi = ~ + 6.5; γOsi = ~ + 1). Primary magma compositions for the Steens Formation do not provide compelling evidence for a subducted slab component, instead suggesting derivation from primitive mantle sources more similar to those of other Mesozoic continental flood basalts (CFB; e.g., Deccan, North Atlantic Igneous Province). Onset of sulfide saturation in the CRBG occurs at lower MgO (<7 wt%) than in other CFB (~ 8 wt%) leading to the high Os contents in Steens Formation basalts. Collectively, the Steens Formation exhibits decreasing Os contents, εNdi values and increasing ¹⁸⁷Os/¹⁸⁸Os with decreasing MgO. These geochemical signatures are consistent with increasing crustal contamination to parent melts with time, a feature that is also shared for the CRBG as a whole. Calculations based on Os and Nd isotopes of likely mantle and crust components to different formations of the CRBG indicates a progressive increase in the quantities of crust from ~1 to 2% from Steens Formation magmatism to more than 6% during Grande Ronde and Wanapum eruptions. These results would indicate increasing crustal contamination and enhanced potential cryptic degassing of CO2 in the later, more voluminous stages of CRBG magmatism, after ~16.5 Ma. Unless mantle-derived melts can produce sufficient greenhouse gas emission, there is likely an offset between the inception of the mid-Miocene Climatic Optimum at 17 Ma and maximum CO2 release, indicating that CRBG eruption was a contributing factor to climate change at that time, but not the trigger for it.
