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Earth Systems and Cycles
Published in Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough, Earth Materials, 2019
Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough
Sometimes a rock may melt completely, but often only partial melting occurs, because most rocks contain more than one mineral and different minerals melt at different temperatures. So, some rocks contain relict (leftover) minerals that did not melt and veins or patches of newly produced magma. When such rocks cool, the result is a migmatite, a rock that contains two different distinguishable components. Figure 2.14 shows a migmatite from western Norway. In migmatites, the minerals that did not melt are equivalent to metamorphic minerals, and the minerals that formed from crystallization of partial melts are igneous minerals.
Materials for Additive Manufacturing
Published in Manu Srivastava, Sandeep Rathee, Sachin Maheshwari, T. K. Kundra, Additive Manufacturing, 2019
Manu Srivastava, Sandeep Rathee, Sachin Maheshwari, T. K. Kundra
Binding using melting is another consolidation mechanism which includes partial and full melting of metallic materials. During partial melting, one portion of material remains solid while the other portion is in melted form and the liquefied material spreads inbetween solid particles. Full melting is another prime binding mechanism which results in completely dense components, thus eliminating need for post-processing densification. Thus, melting is a main binding mechanism to produce dense metal parts in DED and PBF processes.
Magmatism and Magmatic Rocks
Published in Aurèle Parriaux, Geology, 2018
In general, during magma creation, if temperatures remain below this maximum temperature, partial melting occurs. The fact that melting is partial and selective implies that the composition of the magma that has already formed must be different from that of the initial rock. We will examine other processes of differentiation that modify the chemical composition of magma.
Formation of Cu–Au porphyry deposits: hydraulic quartz veins, magmatic processes and constraints from chlorine
Published in Australian Journal of Earth Sciences, 2023
G. N. Phillips, J. R. Vearncombe, J. D. Clemens, A. Day, A. F. M. Kisters, B. P. Von der Heyden
The host rocks for porphyry Cu–Au deposits span a variety of settings in the crust and mantle. The dominant minerals that link the main, unaltered host rocks of diorite, quartz diorite, monzodiorite and granodiorite are plagioclase, lesser K-feldspar and minor to moderate quartz contents, with additional biotite and hornblende. Granodiorites that are not associated with Precambrian trondhjemite–tonalite–granodiorite series can have a variety of origins. These origins include fractionation from enriched mantle parental magmas, such as K-rich diorites, and possibly magma mixing, although this is disputed (e.g. Frost & Mahood, 1987). Brown (2001) pointed out that granitic magmas (granites to granodiorites) are the necessary complements to the melt-depleted granulites commonly formed in the deep crust (e.g. Arth & Hanson, 1972; Otamendi et al., 2009). For the majority of granodiorites (and other I-type granitic rocks), Clemens et al. (2011) showed that the only mechanism that simultaneously explains their major-element, trace-element, isotopic and mineralogical characteristics is partial melting of pre-existing meta-igneous crustal rocks, with variable entrainment of the solid products of the melting reactions. Recent summaries of the evidence can be found in Clemens (2012) and Brown (2013). Some of the more mafic plutonic rocks (such as diorites and monzodiorites), which also host Cu–Au porphyry deposits, are likely to represent magmas produced largely through partial melting of enriched mantle and subsequent differentiation or hybridisation (e.g. Shaw et al., 1993).