Jussi S. Heinonen

• PhD, docent
• Research Leader at Åbo Akademi University

The Merensky Reef of the Bushveld Complex represents a magmatic unconformity that some researchers attribute to chamber replenishment by relatively primitive magma. It is propounded that cumulate rocks in this chamber reacted with replenishing melt, as part of the process that ultimately produced chromitite stringers and reef-style platinum-group e...

The copper-nickel(-platinum-group element) sulfide resources of the Duluth Complex, Minnesota, USA, formed by assimilation of sulfur from the Virginia Formation black shale. In the normal black shale of the Virginia Formation, sulfur is mainly hosted in disseminated pyrite, whereas mm-scale pyrrhotite laminae dominate in the sulfur-rich Bedded Pyrr...

The Karoo large igneous province has been divided into rift zone and basin-related groups, with picrites from the Luenha river, Mozambique, representing an end-member of the latter. New O isotope, major and trace element data for olivine have been combined with MELTS crystallisation modelling to deconvolve compositional diversity associated with ma...

Supplementary materialsfor: Heavy rare earth elements and the sources of continental flood basalts. JS Heinonen, EL Brown, ST Turunen, AV Luttinen Journal of Petrology 63 (10), egac098. (2022) https://doi.org/10.1093/petrology/egac098

Rare earth elements (REEs) in mafic and ultramafic volcanic rocks are useful recorders of mantle source processes because REE ratios are not easily modified by differentiation. Here we utilize REEBOX PRO, a simulator of adiabatic decompression melting of the mantle, to study the behavior of heavy REEs (HREEs) in the formation of continental flood b...

Phase equilibria modeling is a powerful petrological tool to address both forward and inverse geological problems over a broad range of crustal and upper mantle conditions of pressure (P), temperature (T), composition (X), and redox (fO2). The development of thermodynamic databases, relatively realistic activity−composition (a−X) relations for soli...

The Paleoproterozoic Näränkävaara layered intrusion, northern Finland, has a surface area of 25 km x 5 km and a stratigraphic thickness of ~3 km. The main body of the intrusion includes a 1.5–2 km thick basal dunite series and a 1.3 km thick peridotitic-dioritic layered series, the latter with two peridotitic reversals related to magma recharge. In...

Several mafic-ultramafic layered intrusions were emplaced in the NE Fennoscandian Shield during a magmatic episode at 2.44 Ga. The Paleoproterozoic Näränkävaara layered intrusion, northern Finland, is one of the largest ultramafic bodies in the Fennoscandian Shield, with a surface area of 25 km x 5 km and a magmatic stratigraphic thickness of ~3 km...

Supplementary materials for: Thermodynamic constraints on the petrogenesis of massif-type anorthosites and their parental magmas. R Fred, JS Heinonen, A Heinonen, WA Bohrson Lithos 422, 106751. (2022) https://doi.org/10.1016/j.lithos.2022.106751

The Bushveld Complex in South Africa shows spectacular examples of regional and local magmatic erosion of the floor cumulates by new melt batches that replenished the evolving magma chamber. Field observations indicate that, at some stratigraphic levels, at least, 15-20 m of pre-existing floor cumulates, often nearly monomineralic in composition (e...

Development of computational modeling tools has revolutionized studies of magmatic processes over the last four decades. Their refinement from binary mixing equations to thermodynamically controlled geochemical assimilation models has provided more comprehensive and detailed modeling constraints of an array of magmatic systems. One of the questions...

Wall-rock assimilation can cause effective sulfide saturation in magmas and lead to the formation of base and precious metal sulfide deposits. Detailed assessments of how assimilation affects the sulfur content at sulfide saturation (SCSS) in magmas have been scarce because of the lack of suitable thermodynamic modeling tools. The Magma Chamber Sim...

Supplementary materials for: Modelling the formation of linear geochemical trends using the Magma Chamber Simulator: a case study of the Jindabyne granitoids, Lachlan Fold Belt, Australia. KA Iles, JS Heinonen Journal of Petrology 63 (1), egab102. (2022) https://doi.org/10.1093/petrology/egab102

Some geochemical models for basaltic and more primitive rocks suggest that their parental magmas have assimilated tens of weight percent of crustal silicate wall rock. But what are the thermodynamic limits for assimilation in primitive magmas? We pursue this question quantitatively using a freely available thermodynamic tool for phase equilibria mo...

Understanding the origins of major and trace element variations and the isotopic character of granite samples in terms of sources and magmatic processes is, arguably, the core of granite petrology. It is central to attempts to place these rocks in the context of broader geologic processes and continent evolution. For the granites of the Lachlan and...

Magmas readily react with their wall-rocks forming metamorphic contact aureoles. Sulphurand possibly metal mobilization within these contact aureoles is essential in the formation o feconomic magmatic sulphide deposits. We performed heating and partial melting experiments on a black shale sample from the Paleoproterozoic Virginia Formation, which i...

Magmas readily react with their wall-rocks forming metamorphic contact aureoles. Sulphur and possibly metal mobilization within these contact aureoles is essential in the formation of economic magmatic sulphide deposits. We performed heating and partial melting experiments on a black shale sample from the Paleoproterozoic Virginia Formation, which...

The interactions of magmas with their surroundings are important in the evolution of igneous systems and the crust. In this chapter, we conceptually distinguish assimilation from other modes of magmatic interaction and discuss a range of geochemical assimilation models. We define assimilation in its simplest form as an end‐member mode of magmatic i...

Two subvertical gabbroic dikes with widths of ~ 350 m (East-Muren) and ≥ 500 m (West-Muren) crosscut continental flood basalts in the Antarctic extension of the ~ 180 Ma Karoo large igneous province (LIP) in Vestfjella, western Dronning Maud Land. The dikes exhibit unusual geochemical profiles; most significantly, initial (at 180 Ma) ε Nd values in...

Several mafic-ultramafic layered intrusions were emplaced in the Fennoscandian Shield during wide-spread mantle-sourced magmatism at 2.5–2.4 Ga. The Näränkävaara intrusion (surface area 5 × 30 km2), northeastern Finland, contains a 1.5–2 km thick basal dunite (not dated), and a 1.5 km thick layered series (2436 ± 5 Ma). A newly discovered marginal...

We present preliminary results of six new whole-rock Sm-Nd isotope analyses, with samples from both the layered series and the 'basal dunite' series of the Precambrian Näränkävaara intrusion. Because the basal dunite series is mostly composed of low-porosity olivine adcumulates and exhibits several lithological features that are typically found in...

The origin of ferroan A-type granites in anorogenic tectonic settings remains a long-standing petrological puzzle. The proposed models range from extreme fractional crystallization of mantle-derived magmas to partial melting of crustal rocks, or involve combination of both. In this study, we apply whole-rock chemical and Sm-Nd isotopic compositions...

Magmas readily react with their surroundings, which may be other magmas or solid rocks. Such reactions are important in the chemical and physical evolution of magmatic systems and the crust, for example, in inducing volcanic eruptions and in the formation of ore deposits. In this contribution, we conceptually distinguish assimilation from other mod...

About 20 mafic-ultramafic layered intrusions in the northern Fennoscandian shield were emplaced during a widespread magmatic event at 2.5–2.4 Ga. The intrusions host orthomagmatic Ni-Cu-PGE and Cr-V-Ti-Fe deposits. We update the magmatic stratigraphy of the 2.44-Ga Näränkävaara mafic-ultramafic body, northeastern Finland, on the basis of new drill...

The Magma Chamber Simulator (MCS) is a thermodynamic tool for modeling the evolution of magmatic systems that are open with respect to assimilation of partial melts or stoped blocks, magma recharge + mixing, and fractional crystallization. MCS is available for both PC and Mac. In the MCS, the thermal, mass, and compositional evolution of a multicom...

The Magma Chamber Simulator (MCS) is a thermodynamic model that computes the phase, thermal, and compositional evolution of a multiphase-multicomponent system of a Fractionally Crystallizing resident body of magma (i.e., melt ± solids ± fluid), linked wallrock that may either be assimilated as Anatectic melts or wholesale as Stoped blocks, and mult...

Fe–Ti–P-rich mafic to intermediate rocks (monzodiorites and oxide–apatite–gabbronorites, OAGNs) are found as small intrusions in most AMCG (anorthosite–magnerite–charnokite–granite) suites. The origin of the monzodioritic rocks is still debated, but in many studies, they are presumed to represent residual liquid compositions after fractionation of...

Arclogites, i.e., lower crustal garnet-pyroxenite cumulates, are suggested to play an important role in controlling magma differentiation in modern continental arcs. Until now, arclogite-related magmatism has only been described from the Phanerozoic Era. The Svecofennian orogen in the central Fennoscandian Shield hosts a rare association of 1.86 Ga...

Archean terranes are generally poorly exposed and structurally complicated, making models of geological evolution difficult to establish. Because of pervasive metamorphism, strong deformation, and poorly exposed bedrock, the stratigraphy, geochronology, and geological evolution of the northeastern part of the Archean Western Karelia Subprovince, Fi...

The Magma Chamber Simulator (MCS) quantitatively models the phase equilibria, mineral chemistry, major and trace elements, and radiogenic isotopes in a multicomponent–multiphase magma + wallrock + recharge system by minimization or maximization of the appropriate thermodynamic potential for the given process. In this study, we utilize MCS to deciph...

Supplementary tables A2 and A3: SIMS standards data

Supplementary figures

Supplementary data table A4: Whole rock data. From publication DOI: 10.1016/j.gca.2016.09.015

Supplementary table A1: Melt inclusion data. From publication DOI: 10.1016/j.gca.2016.09.015

We present geochemical and isotopic (Nd, Sr) data for a picrite lava suite from the Luenha River and adjacent areas in Mozambique. The Luenha picrites represent a previously unknown type of picrites related to the Karoo large igneous province (LIP) and are distinguished by their notably low TiO2 contents (0.3–1.0 wt%) and coupling of high Nb/Y with...

Karoo continental flood basalt (CFB) province is known for its highly variable trace element and isotopic composition, often attributed to the involvement of continental lithospheric sources. Here, we report oxygen isotopic compositions measured with secondary ion mass spectrometry for hand-picked olivine phenocrysts from ~ 190 to 180 Ma CFBs and i...

Nickel contents and Mn/Fe in olivine phenocrysts have been suggested to reflect the mineral composition of the mantle source of the host magma. This hypothesis is tested here against a well-characterized suite of meimechitic (or Ti-rich komatiitic) dikes from the Antarctic extension of the Jurassic ~180 Ma Karoo large igneous province. The presente...

The 1628* Ma old Luumäki gem beryl pegmatite is hosted by rapakivi granites of the Wiborg batholith in southeast Finland. The moderately evolved niobium-yttrium-fluorine (NYF) pegmatite system belongs to the topaz-beryl type of the rare-element pegmatite class. It has a simple major mineral assemblage of K-feldspar + plagioclase + quartz + biotite...

We present major and trace element compositions of 154 re-homogenised olivine-hosted melt inclusions found in primitive rocks (picrites and ferropicrites) from the Mesozoic Paraná–Etendeka and Karoo Continental Flood Basalt (CFB) provinces. The major element compositions of the melt inclusions, especially their Fe/Mg ratios, are variable and errati...

We present an updated paleomagnetic pole and a new isotope age for the late Paleoproterozoic (Svecofennian) diabase dykes from Keuruu, Central Finland. The paleomagnetic results reveal a dual-polarity remanent magnetization with asymmetry, which we explain by an unremoved secondary component contaminating both normal (N) and reversed (R) vectors. T...

Granitic pegmatites are important hosts for economically important rare-element and gemstone deposits, but the magmatic and hydrothermal processes responsible for enrichment of rare-elements and formation of gem-bearing miarolitic pockets are not fully understood. The Luumäki gem beryl-bearing pegmatite is located within the Wiborg batholith in SE...

Continental flood basalts (CFBs) represent large-scale melting events in the Earth’s upper mantle and show considerable geochemical heterogeneity that is typically linked to substantial contribution from underlying continental lithosphere. Large-scale partial melting of the cold subcontinental lithospheric mantle and the large amounts of crustal co...

The massive outpourings of Karoo and Ferrar continental flood basalts (CFBs) ∼180 Ma ago mark the initial Jurassic rifting stages of the Gondwana supercontinent. The origin and sources of these eruptions have been debated for decades, largely due to difficulties in defining their parental melt and mantle source characteristics. Recent findings of F...

Calculating reliable temperatures of Mg-rich magmas is problematic because melt composition and KD(Fe-Mg)ol-liq, the key parameters of many traditional thermometers, are difficult to constrain precisely. The recently developed Al-in-olivine thermometer [Coogan, L.A., Saunders, A.D., Wilson, R.N., 2014. Aluminum-in-olivine thermometry of primitive b...

The Jurassic Vestfjella dyke swarm at the volcanic rifted margin of western Dronning Maud Land represents magmatism related to the incipient Africa-Antarctica rift zone; that is, rift-assemblage magmatism of the Karoo continental flood basalt (CFB) province. Geochemical and Nd-Sr isotopic data for basaltic and picritic dyke samples indicate diverse...

The great majority of continental flood basalts (CFBs) have a marked lithospheric geochemical signature, suggesting derivation from the continental lithosphere, or contamination by it. Here we present new Pb and Os isotopic data and review previously published major element, trace element, mineral chemical, and Sr and Nd isotopic data for geochemic...

There is a substantial debate on the mantle sources and ultimate origins of continental flood basalts (CFBs), e.g., whether they are related to deep-seated thermal upwellings (i.e. mantle plumes) in the upper mantle or not. Here we present high-precision isotopic (Sr, Nd, Pb, and Os) whole-rock data on some primitive dike rocks (ferropicrites, meim...

Abstract Primitive rocks that are related to continental flood basalts are rare, but often reveal crucial information on the ultimate sources of these huge outpourings of mantle-derived magma. Here we present mineral chemical data for mafic and ultramafic dikes from the Antarctic extension of the Jurassic (~ 180 Ma) Karoo continental flood basalt p...

This study provides insights into the composition and origin of ferropicrite dikes (FeOtot = 13–17 wt. %; MgO = 13–19 wt. %) and associated meimechite, picrite, picrobasalt, and basalt dikes found at Vestfjella, western Dronning Maud Land, Antarctica. The dikes crosscut Jurassic Karoo continental flood basalts (CFB) that were emplaced during the ea...

We present a comprehensive mineral chemical dataset (∼400 analyses) on subalkaline meimechitic (Mg-number = 74–80) and ferropicritic (Mg-number = 67–69) dike samples from the Antarctic extension of the Karoo large igneous province (LIP) in Vestfjella, western Dronning Maud Land. Some of the meimechites, previously considered to be cumulates from fe...

Ferropicrites and their differentiates make up a geochemically distinctive group of dikes that crosscut Jurassic continental flood basalts of the Karoo large igneous province at Vestfjella, western Dronning Maud Land, Antarctica. The Vestfjella ferropicrites can be divided into two geochemical types: The depleted ferropicrites have (La/Sm)N of 1.2–...