Abstract Identification of large-volume, short-duration mafic magmatic events of intraplate affinity in both continental and oceanic settings on the Earth and other planets provides invaluable clues for understanding several vital geological issues of current concern. Of particular importance is understanding the assembly and dispersal of supercontinents through Earth's history, dramatic climate change events including mass extinctions, and processes that have produced a wide range of large igneous province (LIP)-related resources such as Ni–Cu–PGE, Au, U, base metals and petroleum. This current volume presents some of the latest developments and new information on the temporal and spatial distribution of LIPs in both the Precambrian and Phanerozoic, their origin, the plumbing system of mafic dyke swarms, sill provinces and layered intrusions, and links to mantle plume/superplume events, supercontinent reconstructions and associated metallogeny.

Abstract The decompressional release of magma at continental triple-rift break-up, large igneous province (LIP) centres, above mantle plume stems, results in highly magmatic settings. As a particularly well-exposed example, it is proposed that the East Greenland coastal dyke swarm preserves a structural record of how dyke dilations v. tectonic extension increased upon approaching its Kangerlussuaq triple rift centre. Such more magmatic break-up is reflected by how abruptly its volcanic rifted margin transitions into 100% dykes, and, in this case, up to 100 km further inland than its geophysically determined continent–ocean boundary. Correspondingly high magma flux through an igneous Kap Edward Holm centre sustained the lateral injection of up to 150 km-long dykes, evidenced by increased cut-off dyke thicknesses, below which there is an anomalously low abundance of thinner dykes, that conform to the cube root of their thermal arrest distance. Only the thickest and, thereby, longest dyke injections linked up with a more southerly located igneous Imilik centre of an en echelon offset dyke swarm, the complex transition into which is also addressed. This highly magmatic central plumbing system is further compared to similar volcanic zones across Iceland and other post-Paleozoic break-up LIPs in order to contextualize its importance.

Abstract The 1.1 Ga Midcontinent Rift System (MRS) of North America comprises a series of Mesoproterozoic flood basalts and intrusive rocks emplaced in the Lake Superior region. The mafic rocks preserved on the NW flank of Lake Superior offer insights into the early development of the rift. New geochemical data collected from intrusive rocks in the Logan Basin, coupled with improved constraints on timing relationships between units, allow for a better understanding of the geochemical evolution of intrusive rocks therein. The extensive dataset suggests many previously unrecognized relationships between MRS intrusive rocks, indicating multiple, distinct mantle-source characteristics with highly variable crustal contamination histories, implying a complicated magma plumbing system. The data presented here suggest that five geochemically distinct mantle source regions were involved in the emplacement of the Logan Igneous Suite, each with its own distinct contamination history and perhaps different degrees of partial melting. The geochemical variations could suggest either a progressive, relative depletion in the mantle source over time or heterogeneity of the source region. However, based on the model for MRS magmatism presented here, we suggest that units related to the Logan Igneous Suite were tapping a heterogeneous mantle source that varied over time.

Abstract Continental flood basalt provinces (CFBPs) are large igneous features formed by the extrusion of massive amounts of lavas that require significant evolution within the lithosphere. Although sequential lava flows are effective probes of magmatic systems, CFBPs are typically poorly preserved. We focus on lava flows from the well-preserved 1.1 Ga Keweenawan CFBP that erupted within the Midcontinent Rift System. We present a new geochemical, petrographic, and stratigraphic synthesis from the Main stage Portage Lake Volcanics (PLV). Flow-by-flow analysis of the PLV reveals that major element behaviour is decoupled from trace element behaviour; MgO exhibits limited variability, while compatible and incompatible trace elements deviate from high to low concentrations throughout the sequence. The concentrations of incompatible trace elements slightly decrease from the base of the sequence to the top. We investigate these observations by applying a recharge, evacuation, assimilation and fractional crystallization model to geochemical and petrographic data. Our modelling demonstrates a magmatic system experiencing increased evacuation rates while fractionation and assimilation rates decrease, indicating an increase in magmatic flux. The outcome of this modelling is a progressively more efficient magma system within the PLV. This study highlights the utility of joint petrographic and geochemical interpretation in constraining CFBP magma evolution.

Abstract Geological, geochemical, isotopic and geochronological data for Paleoproterozoic mafic intrusions and dykes indicate that distinct magmatic events dated at c. 2.50, 2.45, 2.40, 2.30, 2.23 and 2.12 Ga can be distinguished in the Belomorian Province, Eastern Fennoscandian Shield. The similarity of Paleoproterozoic magmatic barcodes for the Belomorian Province and the Karelian Craton in the c. 2.5–2.1 Ga interval suggests a neighbouring position of these crustal segments in an Archean continent. Intensive tectonic and metamorphic reworking of mafic intrusions and dykes in the Belomorian Province during the c. 2.0–1.8 Ga Lapland–Kola Orogeny produced differences in mineral assemblages and tectonic position in comparison with the Karelian Craton.

Abstract The North China craton is encircled by four successive triple-conjugated rifts, which are respectively the centres of large igneous provinces (LIPs) of bimodal compositions, i.e. Xiong'er rift (south, c. 1.78 Ga Taihang LIP), Yanliao rift (north, c. 1.32 Ga Yanliao LIP), Xuhuai rift (east, c. 1.23 Ga Licheng and c. 0.92 Ga Dashigou LIPs) and Langshan rift (west, c. 0.82 Ga Qianlishan LIP). These rifts are genetically related to their contemporaneous LIPs based on their consistent geometry. Spatial migration of these rifts and LIPs indicates their propagation from along one marginal side to the opposite side of the craton, which may have resulted in the sequential breakup of the proto-North China craton from one side to the other during 1.8–0.8 Ga. However, the observation that the lithosphere under the LIP-associated rift regions is less destroyed (decratonized) in the Mesozoic indicates a possible role of LIPs in strengthening intracratonic steady state. This study shows that LIPs may change craton stability in either direction.

Abstract The Archean age granite gneiss basement along the Prydz Bay coastline in East Antarctica hosts north–south-, east–west-, NE–SW- and NW–SE-trending mafic dyke swarms in the Vestfold Hills region that intruded between 2420 and 1250 Ma. The orientations of dykes do not show a direct correlation with the dyke geochemistry. Instead the dykes can be broadly discriminated into high-Mg and Fe-rich tholeiites. The former type is more siliceous, large ion lithophile elements (LILEs), high field strength elements (HFSEs) and light REEs enriched crystallized from a fractionated melt with a notable crustal component or fluid enrichment through the previous subduction process. The Fe-rich tholeiites are less siliceous, have lower abundances of LILEs and REEs, that indicates derivation from an undifferentiated, primitive melt. The geochemical characteristics of both types underline a shallow level and a high degree of melting in the majority of cases, and a broadly island arc basalt (IAB) affinity. Palaeomagnetic analysis of hand samples shows directional groups consistent with geochemical groupings. The Vestfold Hills dykes show a possible linkage with the coeval mafic dykes in the Eastern Dharwar and Bastar cratons of the South Indian Block, based on the similarity in the Paleoproterozoic palaeolatitudes.

Abstract We propose a Precambrian megacraton (consisting of two or more ancient cratons), DHABASI in the Indian Shield, which includes the Dharwar, Bastar and Singhbhum cratons. This interpretation is mainly based on seven large igneous provinces (LIPs) that are identified in these three cratons over the age range of c. 3.35–1.77 Ga, a period of at least 1.6 Ga. The absence of any subsequent break-up of DHABASI since 1.77 Ga suggests that this megacraton has existed for the past 3.35 Ga. In addition to their use in recognizing this megacraton, these LIP events may also provide likely targets for Cu–Ni–Cr–Co–platinum group element deposits. We suggest that the megacraton DHABASI was an integral part of supercontinents/supercratons through Earth's history, and that it should be utilized as a distinct building block for palaeocontinental reconstructions rather than using the individual Dharwar, Bastar and Singhbhum cratons.

Abstract Northern Indian Shield and the western Himalaya have an impressive record of mafic magmatism. The Aravalli Craton preserved 2.3 Ga komatiitic (picritic) and 2.1–1.8 Ga tholeiities. Gwalior and Betul belts preserved 2.1 and 1.5–1.2 Ga tholeiites, respectively. Western Himalaya has preserved 2.1–1.8 Ga tholeiites in Garhwal and Himachal regions. Studied rocks depict enriched rare earth elements, large ion lithophile elements and depleted high field strength elements. Whereas komatiites/picrites represent higher degrees of partial melting ( c. 35–40%) at higher temperatures ( c. 1500°C), tholeiites represent lower degrees of partial melting ( c. 10%) at lower temperatures ( c. 1200°C). Our results indicate interaction of mantle plume with variably enriched subcontinental lithospheric mantle sources, causing generation of these varied magmatic suites of rocks. Whereas the higher temperature komatiitic/picritic melts from the Aravalli region appear to have been generated closer to the plume head, the lower temperature tholeiitic melts from the shield region and western Himalaya were generated towards the plume margins. Different terrains of the study have undergone plume tectonics causing the development of the rift valleys. The majority of these developed into aulacogens, except for the Aravalli basin, which developed into deeper marine facies.

Abstract The Permian silicic rocks in the Phan Si Pan (PSP) Uplift area and Tu Le (TL) basin of NW Vietnam (collectively the PSP–TL region) are associated with the Emeishan large igneous province (ELIP). The Permian Muong Hum, Phu Sa Phin and Nam Xe–Tam Duong granites and Tu Le rhyolites are alkali ferroan A 1 -type granitic rocks, which probably formed by fractional crystallization of high-Ti basaltic magma that was contaminated by melts derived from the Neoproterozoic host rocks. Zircon U–Pb laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) geochronology yielded weighted-mean 206 Pb/ 238 U ages of 246 ± 3 to 259 ± 3 Ma for granites, and 249 ± 3 and 254 ± 2 Ma for rhyolites. This is contrasted with previously published high precision U–Pb ages, obtained using chemical abrasion–isotope dilution–thermal ionization mass spectrometry method applied on the same zircon grains, which suggests that the calculated LA–ICP–MS U–Pb ages are variably inaccurate by up to 10 Ma, although at the single-grain level dates generally agree within uncertainty. The similarity of rock texture, whole-rock geochemistry, emplacement ages and fractionation phases between the PSP–TL region and silicic rocks in the Inner Zone ELIP (i.e. Panzhihua, Binchuan) suggests they were spatially proximal before being sinistrally displaced along the Ailao Shan–Red River shear zone.

Abstract New 40 Ar/ 39 Ar data from dykes intruded into Sverdrupfjella and Ahlmanryggen, Dronning Maud Land, Antarctica, indicate that dyke emplacement commenced at c. 207 Ma and lasted until c. 178 Ma. Whereas the ages ascribed to the Karoo-age magmatism contributing to Gondwana breakup are typically inferred as being c. 182 Ma, the data indicate that ages older than c. 192 Ma in the broader Karoo Province are restricted to western Dronning Maud Land, Antarctica, indicating the locality where breakup was initiated. Limited palaeomagnetic data from c. 178–185 Ma dykes combined with published palaeomagnetic data from similar-aged dykes in Vestfjella and the Ferrar Province, suggest that Antarctica had already drifted/rifted significantly away from southern Africa from c. 207 to c. 180 Ma, earlier than previously thought. The data, if correct, require a re-evaluation of the ages ascribed to ocean-floor anomalies used to constrain reconstructions of Gondwana and may provide insight into the history of microcontinental blocks including the Falkland Islands, Haag nunataks, Ellsworth–Whitmore block and Maurice Ewing Bank.

Abstract We present the results of a geochronological investigation that was conducted on mafic rocks (dolerites) that form two giant dyke swarms in NE Brazil, whose intrusion was correlated to the break-up of the West Gondwana supercontinent and the opening of the Atlantic Ocean. Despite their impressive dimensions, these swarms lack any geological information, which motivated us to develop a speedy, low-cost analytical protocol, modified from the Cassignol unspiked K–Ar technique, to define age patterns. The results were interpreted in light of basic statistical treatments and, although some limitations were mostly related to grain-size heterogeneities, they successfully matched other 40 K-based ages (conventional K–Ar and 40 Ar/ 39 Ar) reported in the literature and showed that the dyke swarms share two main age intervals of rock formation identified as the Early Cretaceous and Late Jurassic.

Abstract We report new U–Pb zircon ages for mafic plutonic (gabbro) and volcanic (andesite) rocks, along with the whole-rock chemistry of a mafic–felsic suite of volcanic rocks from the Siang window of the Eastern Himalayan Syntaxis, NE India. Field relationships, and mineralogical and geochemical characteristics, of the studied mafic–intermediate–felsic rocks suggest their co-magmatic linkage that was generated in an extensional tectonic environment. Incompatible trace elements and low concentrations of large ion lithophile elements (LILEs) and REE behaviour reflect both the enriched nature of the mafic rocks and the limited influence of crustal contamination in their genesis. Partial melting and fractional crystallization processes have played a major role during the genesis of these felsic volcanics from the parental mafic magma. The laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) zircon U–Pb ages suggest that the mafic plutonic rock was emplaced at c. 121.18 ± 1 Ma and intermediate volcanic rock was emplaced at c. 135.48 ± 0.50 Ma during the Early Cretaceous period. The new ages are consistent with earlier reported zircon U–Pb ages (133.0 ± 1.9–130.7 ± 1.8 Ma) of felsic volcanic rocks from the present study area. Our new field observations, and mineralogical and geochemical characteristics, in conjunction with the U–Pb isotopic database suggest that the major magmatic event in the core of the Siang window of the Eastern Himalaya is coeval with the Rajmahal–Sylhet–Mikir–Shillong flood basalts of eastern and northeastern India, and the Comei–Bunbury Large Igneous Province of southeastern Tibet and SW Australia. These events are related to the break-up of eastern Gondwana and outbreak of the Kerguelen plume.

Abstract The Late Cretaceous magmatism in Madagascar is correlated with the break-up between Madagascar and Greater India, with a presumed track of a hotspot from Madagascar towards the Marion Island and with an anoxic event in the Late Cretaceous. The lava succession and associated dyke swarms and sills of western Madagascar (Mailaka area) represent a volumetrically important area of the igneous province, where dykes with random orientation, several igneous intrusions and a flood basalt to rhyodacite sequence do occur. The magmas have a tholeiitic and weakly alkaline affinity. Using plagioclase separates, we obtained two plateau 40 Ar/ 39 Ar ages, and an inverse isochron age statistically indistinguishable, ranging from 92.9 ± 3.8 to 91.2 ± 1.3 Ma (2 σ ). These ages indicate that tholeiitic and alkaline rocks were erupted in the same age span. In addition, these ages are close to the Cenomanian–Turonian (C–T; 93.9 ± 0.2 Ma) boundary and are indistinguishable from the U–Pb ages available for the capping rhyodacitic unit of the Mailaka lava succession. A filtered compilation of eight ages for northern and central-western Madagascar rocks suggests a duration for the magmatic activity in this part of Madagascar province of the order of c. 3 Ma. If the western Madagascar magmatism is plume related, the plume head would need to have been located near the Mailaka area at c. 93 Ma. The geochemistry of the mafic lavas and dykes of western Madagascar is barely distinguishable from mid-ocean ridge basalt (MORB), with an increasing crustal contamination towards the evolved rocks, and does not constrain input of typical components derived by plume magmatism.

Abstract We review and compare morphologies from continental basaltic lavas, using examples from the Deccan Volcanic Province to compile their internal configurations and mutual associations and compare them. The mechanism of endogenous transfer of lava within an insulating (rapidly developed) crust provides an efficient mode of dispersal of the molten lava in flood basalts. The growth of the lava flow can be achieved by a single extrusion or by multiple pulses of endogenous emplacement that enable the lava to efficiently spread over large areas and thicken. We show that the morphology of a lobe manifests the response of the molten lava to several parameters (including volumetric rate of emplacement, substrate topography, viscosity, vapour loss, etc.) that govern the dynamics and cooling history of basaltic lava after it starts to spread on the surface. The lateral transition from one morphology to another within lobes of a lava flow is a testimony to the interactive response of the lava dynamics and rheology to variation in the local systems in which they were emplaced. The morphologies do not evolve as rigid partitioned categories from ‘áā and pāhoehoe lava types' but as parametric progression of interactive variations in the spreading and cooling lava. A hierarchical recognition of lobes, flows and flow fields and mapping of the morphology (and their lateral transition or continuity) combined with the stacking patterns provides the volcanological framework for a sound stratigraphic mapping of flood basalts. Such an architectural documentation of flood basalt provinces will lead to robust models of their eruptive histories.

Abstract The Koyna borehole penetrated c. 1 km through the Deccan basalt units and into the cratonic basement beneath, thus providing a unique insight into the subsurface succession of the main Deccan province. Earlier studies focused on southwestern Deccan lava packages exposed in the Western Ghat escarpment, and resolved a well-constrained stratigraphy and key reference sections, but lacked supporting subsurface data. To construct the stratigraphy and correlate it with the main Deccan formations, we report flow-wise physical and chemical data of a c. 932 m-thick core. We document 37 lava-flow units and four lava-flow groups that have similar major-oxide contents. These groups fit into two of the recognized chemostratigraphic formations, and the transitional Poladpur–Ambenali lavas. In addition, data plots on Ba v. Sr; Ba v. Zr/Nb; Ba/Y v. Zr/Nb; and Ba, Sr, Ba/Y, Zr/Nb v. height bivariate diagrams confine them to the Poladpur and Ambenali formations. Lava flows match with the Khumbarli and Mahabaleshwar Ghat sections and Killari core. The granitoid basement–basalt and the Poladpur Formation v. Ambenali Formation contacts lie at −332.5 and c. 482 m above sea-level, respectively. Further, the new data endorse the southern overstepping of chemostratigraphic units and the asymmetry of the Deccan edifice due to the northward motion of the Indian Plate over the nascent Réunion plume ( c. 67–64 Ma). For comparison, the oldest 66.4 Ma lava flow predates the Cretaceous–Paleogene boundary (KPB) (66.052 Ma) by <0.35 Ma, with much of the Wai Subgroup erupted syn-KPB or >0.55 Ma post-KPB; however, the restricted lava thickness at the contact between the Poladpur and Ambenali formations provides a reference point in the Deccan stratigraphy.

Abstract The initial interaction between material rising from the African Large Low Shear Velocity Province and the African lithosphere manifests as the Eocene continental large igneous province (LIP), centred on southern Ethiopia and northern Kenya. Here we present a geographically well-distributed geochemical dataset comprising flood basalt lavas of the Eocene continental LIP to refine the regional volcano-stratigraphy into three distinct magmatic units: (1) the highly alkaline small-volume Akobo Basalt (49.4–46.6 Ma), representing the initial phase of flood basalt volcanism derived from the melting of lithospheric–mantle metasomes; (2) the primitive and spatially restricted Amaro Basalt (45.2–39.8 Ma), representing the early main phase of flood basalt volcanism derived from the melting of the upwelling thermochemical anomaly; and (3) the spatially extensive Gamo–Makonnen magmatic unit (38–28 Ma), representing the mature main phase of flood basalt volcanism that has undergone significant processing within the lithosphere and resulted in relatively homogeneous compositions. The focused intrusion of these main phase magmas over 10 myr preconditioned the African lithosphere for the localization of strain during subsequent episodes of lithospheric stretching. The focusing of strain into the region occupied by this continental LIP may have contributed to the initial extension in SW Ethiopia that is associated with the East African Rift.

Abstract In this contribution, I discuss the putative link of mantle plumes with selected categories of mineral systems. Continental rifting and break-ups can be induced by the upwelling of mantle plumes, also resulting in the generation of a wide range of mineral deposits. These include magma-associated ores, anorogenic igneous events responsible for iron oxide–copper–gold (IOCG) deposits, carbonatites and hydrothermal-induced mineralization, as well as hydrocarbons, salt domes, petroleum and gas, and several mineral systems in continental passive margins. Amongst the magma-associated mineral systems, the Ni–Cu–platinum group element (PGE), Fe–Ti–V and Cr deposits are the economically most important, such as those of the Bushveld Igneous Complex in South Africa. Anorogenic magmas are generally alkaline and associated with IOCG mineral systems, as exemplified by the giant Olympic Dam and similar deposits in South America. Carbonatites are considered as a distal effect of hotspot mantle plumes, as shown by Mount Weld in Australia, which may be related to the Bushveld Superplume. Plume-related thermal anomalies are the principal factor for the inception of hydrothermal circulation and the genesis of a wide range of hydrothermal mineral systems in rift-related tectonic settings. These include large-scale sedimentary-rock-hosted metalliferous ores, such as sedimentary exhalative (SEDEX) deposits. A modern example of is provided by the Red Sea brine pools. Some key examples are presented in this paper.