The calculated degrees of partial melting for the massive chromites are 21%−22%, and for the disseminated chromites in peridotites the degrees are 17%−18%. The calculated …

The Bushveld Igneous Complex (BIC) is known for its laterally extensive platinum group element–bearing layers, the most famous being the Merensky Reef and the UG-2 chromitite in the eastern and western limbs of the complex. In the northern limb, the Platreef mineralization and a thick chromitite seam below it (referred to as the "UG-2 equivalent" or UG …

The traditional interpretation of such layers in the frame of gravity settling models is that chromite was the first to settle on the chamber floor 32 – 35 followed, after some period of post-depositional cooling, by in situ growth of plagioclase oikocrysts from the interstitial melt in a mushy chromitite. An important point is that settling ...

The dunite/chromitite boundary shows an interlocking texture; olivine inclusions in chromites in the podiform chromitites show the same optical extinction with larger adjacent olivines in the dunite clots. ... This bimodal occurrence has been attributed to differing conditions in terms of multi-stage melting, high water pressure and oxygen ...

The Jacurici Complex hosts the largest chromite deposit in Brazil in an up to 8-m-thick chromitite layer within a tectonically segmented 300-m-thick intrusion. The ore has been interpreted as the result of crustal contamination-driven crystallization in a magma conduit. This study addresses the stratigraphy, mineralogical and textural relationships, and mineral …

A magmatic dropstone approach has not yet been applied to a problem of massive chromitites in mafic layered intrusions although it has been already employed to address a few petrological problems such as the origin of igneous layering (e.g., Irvine et al., 1998).Importantly, the vast majority of the layered intrusions lack any rocks that grew from the roof downward …

The modes were determined by point counting (minimum 450 points) of individual thin sections. opx, orthopyroxene; plag, plagioclase; cpx, clinopyroxene; chr, chromite; qtz þ k-felds, quartz þ K ...

The element with the lowest melting point is helium, with a melting point of 0.95 K (−272.20 °C, −457.96 °F) at 2.5 MPa pressure. This is very near absolute zero . The metal with the lowest melting point is mercury, with a melting point of …

X-ray elemental mapping of an acicular inclusion in Fig. 1 d shows that the inclusion is rich in Si and Ca (Fig. 1 g). A typical energy-dispersive X-ray spectrum by TEM reveals a composition typical of diopside - CaMgSi 2 O 6 (Fig. 1 h). The TEM analyses of the needle-like grains show both crystalline and amorphous varieties (Fig. 2).A selected area …

Photomicrographs of ophiolite-hosted diamonds from chromitite and peridotite. (a) Diamonds from the Ray-Iz chromitite, Russia [17]; (b) diamonds from the Pozanti-Karsanti (Aladag) chromitite ...

may help cause a slab window and partial melting in the deep mantle (e.g.,MTZ), chromite (or its high-pressure polymorphs) and other UHP-minerals can be formed in the Cr-rich melt; finally, …

Now that you understand what is melting point, here is a look at how pressure affects melting points. Pressure and its Effect on Melting Point. In most cases, increased pressure increases the melting point for a material. This means that under high-pressure conditions, you would need to apply more heat to cause a material to melt.

| the formation of diamond and chromitite in Earth's mantle. Subduction carries oceanic and continental crustal material, along with oceanic lithosphere, down to the mantle transition zone or even ...

Recent geochemical and geochronological data from many ophiolites in different orogenic belts have shown strong evidence for structural and compositional heterogeneity in their crustal and mantle units, and for multiple episodes of melt extraction, melt-rock reactions, and melt migration in their mantle evolution history (Batanova et al., 1998; Morishita et al., 2006; Aldanmaz et al., …

This contribution provides an overview of platinum group elements (PGE) distribution and mineralogy in ophiolitic chromitites, which are unusually enriched in the low melting-point Rh, Pt and...

Therefore, a change in pressure to account for the UG2 chromitite is not consistent with the observations. MARCH 2007 Addition of water Nicholson & Mathez (1991) proposed that the thin chromitite seams of the Merensky Reef formed at fronts of hydrous interstitial melt migrating through the crystal pile.

Differentiation of the continental crust begins with its partial melting. The products of crustal melting are silicic, hydrous, H2O-undersaturated, granitic liquids that are generated within ...

Ultra-high pressure inclusion in Archean ophiolitic podiform chromitite in mélange block suggests deep subduction on early Earth ... resulting in adiabatic melting that allowed crustal material to be trapped in chromite grains crystallizing in high-Mg melts. ... is almost absent in the central CNCC (only 6% data points) but spread throughout ...

The stability of anhydrous phase B, Mg14Si5O24, has been determined in the pressure range of 14–21 GPa and the temperature range of 1100–1700 °C with both normal and reversal experiments ...

The calc-alkaline andesitic rocks and sanukitoids were produced by partial melting of metasomatic domains that were generated by reaction of the mantle wedge peridotite with the hydrous melts, but ...

The formation of a chromitite body, its size and type of chromitite microstructures could reflect focused melt flow within these high-porosity and high-permeability networks of …

chromitite layer marks the point where there was a substantial injection of new magma into the chamber, ... melt. The chromitites represent, therefore, the products

The melting point is that temperature at which a solid is converted into a liquid. The effect of pressure of the melting point of a solid depends on whether it is expanding or contracting on melting. In case of majority of solids, the melting point increases with increase in pressure as the solid itself is usually more dense than the liquid.

More recently, the identification of ultra-high pressure (UHP) ... Conversely, the lack of water in MOR mantle makes it difficult to meet the conditions for producing boninitic melt and podiform chromitite. Methods. Electron probe microanalysis (EPMA). Major-element compositions of chromite and clinopyroxene were obtained using a JEOL JXA8530F ...

melting point of 1553 °C (at atmospheric pressure; Fig. 4 a). The first question to answer was that what is the maximum mass of floor cumulates that the superliquidus melts can assimilate without in-

In this study, we present field and microtextural data on chromitites from the Bushveld Complex whose formation require many times their own volume of magma to supply …

Some of the focus points and/or findings presented in these papers are summarized as follows: the chemical and mineralogical characteristics of chromitite can be used to determine the tectonic ...

I don't believe there is an equation that you can use for melting points of a general substance as a function of pressure (since the melting phase transition has a lot to do with the geometry of the molecule and the structure of the solid), but there is one for the boiling point of any pure substance when you are not near the critical point.. The liquid-vapor transition follows a very …

The olivine and chromitite δ18Oolivine/chromite and δ18Omelt values point out these minerals and melt isotopic compositions similar to mantle values and rich, heavy stable isotopes. The highest δ18Ochromite isotopic composition values indicate that as the heavy isotope in the melt increases, the concentration in the mineral increases.

Thermodynamic modelling results reveal a wedge-shaped domain in pressure-temperature space in the subcratonic mantle within which Cr-bearing orthopyroxene forms as …