Binäärisestä sekoittumisesta Magmakammiosimulaattoriin - Assimilaation geokemiallinen mallinnus magmaattisissa systeemeissä

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 modes of magmatic interaction and discuss and review a range of geochemical (+/- thermodynamical) models used to model assimilation. We define assimilation in its simplest form as an end-member mode of magmatic interaction in which an initial state (t0) that includes a system of melt and solid wallrock evolves to a later state (tn) where the two entities have been homogenized. In complex natural systems, assimilation can refer more broadly to a process where a mass of magma wholly or partially homogenizes with materials derived from wallrock that initially behaves as a solid. The first geochemical models of assimilation used binary mixing equations and then evolved to incorporate mass balance between a constant-composition assimilant and magma undergoing simultaneous fractional crystallization. More recent tools incorporate energy and mass conservation in order to simulate changing magma composition as wallrock undergoes partial melting. For example, the Magma Chamber Simulator utilizes thermodynamic constraints to document the phase equilibria and major element, trace element, and isotopic evolution of an assimilating and crystallizing magma body. Such thermodynamic considerations are prerequisite for understanding the importance and thermochemical consequences of assimilation in nature, and confirm that bulk assimilation of large amounts of solid wallrock is limited by the enthalpy available from the crystallizing resident magma. Nevertheless, the geochemical signatures of magmatic systems-although dominated for some elements (particularly major elements) by crystallization processes-may be influenced by simultaneous assimilation of partial melts of compositionally distinct wallrock.Peer reviewe

Surgical treatment of chronic acromioclavicular joint dislocation with autogenous tendon grafts

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Fluids as primary carriers of sulphur and copper in magmatic assimilation

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 is the main source of sulphur for the world-class Cu-Ni sulphide deposits of the 1.1 Ga Duluth Complex, Minnesota. These experiments show that an autochthonous devolatilization fluid effectively mobilizes carbon, sulphur, and copper in the black shale within subsolidus conditions (≤ 700 °C). Further mobilization occurs when the black shale melts and droplets of Cu-rich sulphide melt and pyrrhotite form at ∼1000 °C. The sulphide droplets attach to bubbles of devolatilization fluid, which promotes buoyancy-driven transportation in silicate melt. Our study shows that devolatilization fluids can supply large proportions of sulphur and copper in mafic–ultramafic layered intrusion-hosted Cu-Ni sulphide deposits.</p

Surgical treatment of Rockwood grade-V acromioclavicular joint dislocations 50 patients followed for 15-22 years

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Solisluumurtumien konservatiivinen ja operatiivinen hoito : Systemaattinen kirjallisuuskatsaus 1190 potilaasta

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Molecular understanding of sulphuric acid-amine particle nucleation in the atmosphere

4 pages 359-363 in the print version, additional 7 pages online.Peer reviewe

Fluidit rikin ja kuparin pääasiallisina kuljettajina magmaattisessa assimilaatiossa

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 is the main source of sulphur for the world-class Cu-Ni sulphide deposits of the 1.1 Ga Duluth Complex, Minnesota. These experiments show that an autochthonous devolatilization fluid effectively mobilizes carbon, sulphur, and copper in the black shale within subsolidus conditions ( Experiments show that when magma heats black shale wall-rock, fluids form and mobilize S and Cu, which can then concentrate and form base metal deposits. The fluids also attach to sulphide droplets and cause them to float in the host silicate melt.Peer reviewe

Publisher Correction to: Sedimentary and metamorphic processes priming black shale for magmatic assimilation of sulfur: an example from the Virginia Formation, Minnesota, United States

International audienc

Sedimentary and metamorphic processes priming black shale for magmatic assimilation of sulfur: an example from the Virginia Formation, Minnesota, United States

International audienceThe 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 Pyrrhotite Unit. The Bedded Pyrrhotite Unit was the main supply of sulfur in some of the magmatic sulfide deposits but its origin has not been studied in detail. Using Raman spectroscopy, we show that the carbonaceous material within the regionally metamorphosed normal black shale is graphitized biogenic material. The Bedded Pyrrhotite Unit contains pyrobitumen that represents residues of oil that accumulated to porous horizons, which formed due to dissolution of precursor sedimentary clasts. Replacement of the clasts by quartz and sulfides facilitated the formation of the pyrrhotite laminae of the Bedded Pyrrhotite Unit, which likely occurred during regional metamorphism