In this study the formation of the polygenetic High Tatra granitoid magma is discussed. Felsic and mafic magma mixing and mingling processes occurred in all magma batches composing the pluton and are documented by the typical textural assemblages, which include: mafic microgranular enclaves (MME), mafic clots, felsic clots, quartz-plagioclase-titanite ocelli, biotite-quartz ocelli, poikilitic plagioclase crystals, chemically zoned K-feldspar phenocrysts with inclusion zones and calcic spikes in zoned plagioclase. Geochemical modelling indicates the predominance of the felsic component in subsequent magma batches, however, the mantle origin of the admixed magma input is suggested on the basis of geochemical and Rb-Sr, Sm-Nd and Pb isotopic data. Magma mixing is considered to be a first-order magmatic process, causing the magma diversification. The cumulate formation and the squeezing of remnant melt by filter pressing points to fractional crystallization acting as a second-order magmatic process.
Many granitic intrusions display evidence of magma mixing processes. The interaction of melts of contrasting composition may play a significant role during their generation and evolution. The Strzegom-Sobótka massif (SSM), located in the Sudetes (SW Poland) in the north-eastern part of the Bohemian Massif of the Central European Variscides, exhibits significant evidence of magma mingling on the macro- and micro-scales. The massif is a composite intrusion, with four main varieties: hornblende-biotite granite (with negligible amount of hornblende) and biotite granite in the western part, and two-mica granite and biotite granodiorite in the eastern part. Field evidence for magma mingling is easily found in the biotite granodiorite, where dark enclaves with tonalitic composition occur. Enclaves range from a few centimeters to half a meter in size, and from ellipsoidal to rounded in shape. They occur individually and in homogeneous swarms. The mixing textures in the enclaves include fine-grained texture, acicular apatite, rounded plagioclase xenocrysts, ocellar quartz and blade-shaped biotite. The most interesting feature of the enclaves is the presence of numerous monazite-(Ce) crystals, including unusually large crystals (up to 500 μm) which have grown close to the boundaries between granodiorite and enclaves. The crystallization of numerous monazite grains may therefore be another, previously undescribed, form of textural evidence for interaction between two contrasting magmas. The textures and microtextures may indicate that the enclaves represent globules of hybrid magma formed by mingling with a more felsic host melt. Chemical dating of the monazite yielded an age of 297±11 Ma.
Jotunites (hypersthene monzodiorites/ferromonzodiorites) are rocks coeval with plutonic AMCG (anorthosite– mangerite–charnockite–rapakivi granite) suites, which are characteristic of the Proterozoic Eon. It has been experimentally shown that jotunite magma can be recognised as parental to anorthosites and related rocks: since then, research on these rocks has taken on a particular importance. Jotunites were recently described within the deeply buried c. 1.5 Ga Suwałki and Sejny anorthosite massifs in the crystalline basement of NE Poland. The major and trace element compositions of Polish jotunites show them to have a calc-alkalic to alkali-calcic and ferroan character, with a relatively wide range of SiO2 content (40.56 wt. % up to 47.46 wt. %) and high concentrations of Fe (up to 22.63 wt. % Fe2O3), Ti (up to 4.34 wt. % TiO2) and P (up to 1.46 wt. % P2O5). Slight differences in textural features, mineralogical compositions, and geochemistry of whole-rock jotunite samples from distinct massifs allow us to distinguish two kinds: a primitive one, present in the Sejny Intrusion, and a more evolved one, related to the Suwałki Massif.
For the die casting conditions of aluminium bronzes assumed based on the literature data, a thick-walled bush was cast, made of complex
aluminium bronze (Cu-Al-Fe-Ni-Cr). After the cast was removed from the mould, cracks were observed inside it. In order to identify the
stage in the technological production process at which, potentially, the formation of stresses damaging the continuity of the microstructure
created in the cast was possible (hot cracking and/or cold cracking), a computer simulation was performed. The article presents the results
of the computer simulation of the process of casting the material into the gravity die as well as solidifying and cooling of the cast in the
shape of a thick-walled bush. The simulation was performed with the use of the MAGMA5 program and by application of the
CuAl10Ni5,5Fe4,5 alloy from the MAGMA5 program database. The results were compared with the location of the defects identified in
the actual cast. As a result of the simulation of the die-casting process of this bush, potential regions were identified where significant
principal stresses accumulate, which can cause local hot and cold cracking. Until now, no research has been made of die-cast aluminium
bronzes with a Cr addition. Correlating the results of the computer simulation validated by the analysis of the actual cast made it possible
to clearly determine the critical regions in the cast exposed to cracking and point to the causes of its occurrence. Proposals of changes in
the bush die casting process were elaborated, in order to avoid hot tearing and cold cracking. The article discusses the results of
preliminary tests being a prologue to the optimization of the die-casting process parameters of complex aluminium bronze thick-walled
bushs.