The Role of Partial Melting of Metasediments in the Formation of the Anorthosite-Norite-Syenite Complex, Laramie Range, Wyoming

1975 ◽  
Vol 83 (6) ◽  
pp. 749-762 ◽  
Author(s):  
George W. De Vore
Keyword(s):  
Partial Melting ◽  
Laramie Range

scholarly journals The role of sulphur on the melting of Ca-poor sediment and on trace element transfer in subduction zones: an experimental investigation

2021 ◽  
Author(s):  
Anne-Aziliz Pelleter ◽  
Gaëlle Prouteau ◽  
Bruno Scaillet
Keyword(s):  
Trace Element ◽  
Partial Melting ◽  
Subduction Zones ◽  
Sediment Flux ◽  
Arc Magmas ◽  
Trace Element Contents ◽  
The Stability ◽  
Element Transfer ◽  
High Sediment

Abstract We performed phase equilibrium experiments on a natural Ca-poor pelite at 3 GPa, 750-1000 °C, under moderately oxidizing conditions, simulating the partial melting of such lithologies in subduction zones. Experiments investigated the effect of sulphur addition on phase equilibria and compositions, with S contents of up to ∼ 2.2 wt. %. Run products were characterized for their major and trace element contents, in order to shed light on the role of sulphur on the trace element patterns of melts produced by partial melting of oceanic Ca-poor sediments. Results show that sulphur addition leads to the replacement of phengite by biotite along with the progressive consumption of garnet, which is replaced by an orthopyroxene-kyanite assemblage at the highest sulphur content investigated. All Fe-Mg silicate phases produced with sulphur, including melt, have higher MgO/(MgO+FeO) ratios (relative to S-free/poor conditions), owing to Fe being primarily locked up by sulphide in the investigated redox range. Secular infiltration of the mantle wedge by such MgO and K2O-rich melts may have contributed to the Mg and K-rich character of the modern continental crust. Addition of sulphur does not affect significantly the stability of the main accessory phases controlling the behaviour of trace elements (monazite, rutile and zircon), although our results suggest that monazite solubility is sensitive to S content at the conditions investigated. The low temperature (∼ 800 °C) S-bearing and Ca-poor sediment sourced slab melts show Th and La abundances, Th/La systematics and HFSE signatures in agreement with the characteristics of sediment-rich arc magmas. Because high S contents diminish phengite and garnet stabilities, S-rich and Ca-poor sediment sourced slab melts have higher contents of Rb, B, Li (to a lesser extent), and HREE. The highest ratios of La/Yb are observed in sulphur-poor runs (with a high proportion of garnet, which retains HREE) and beyond the monazite out curve (which retains LREE). Sulphides appear to be relatively Pb-poor and impart high Pb/Ce ratio to coexisting melts, even at high S content. Overall, our results show that Phanerozoic arc magmas from high sediment flux margins owe their geochemical signature to the subduction of terrigenous, sometimes S-rich, sediments. In contrast, subduction of such lithologies during Archean appears unlikely or unrecorded.

An experimental study of the role of shear deformation on partial melting of a synthetic metapelite

2011 ◽  
Vol 503 (1-2) ◽  
pp. 92-99 ◽  
Author(s):  
Elizaveta Tumarkina ◽  
Santanu Misra ◽  
Luigi Burlini ◽  
James A.D. Connolly
Keyword(s):  
Experimental Study ◽  
Partial Melting ◽  
Shear Deformation

The role of subgrain boundaries in partial melting

2016 ◽  
Vol 89 ◽  
pp. 181-196 ◽  
Author(s):  
Jamie S.F. Levine ◽  
Sharon Mosher ◽  
Jeffrey M. Rahl
Keyword(s):  
Partial Melting

Fluid processes during the exhumation of high-P metamorphic belts

2002 ◽  
Vol 66 (1) ◽  
pp. 93-119 ◽  
Author(s):  
J. A. Miller ◽  
I. S. Buick ◽  
I. Cartwright ◽  
A. Barnicoat
Keyword(s):  
Fluid Flow ◽  
Partial Melting ◽  
Significant Role ◽  
Large Scale ◽  
Shear Zones ◽  
Direct Role ◽  
Detachment Faults ◽  
Dehydration Reactions ◽  
Exhumation History

AbstractFluids can play a direct role in exhumation by influencing exhumation mechanisms and the driving processes for these mechanisms. In addition, the process of exhumation leads to the development of fluid-related features that in themselves may not drive exhumation. Fluids involved in exhumation are generally derived from dehydration reactions occurring during decompression, but at shallower crustal levels may also involve the introduction of exotic fluids. The composition of fluids attending exhumation are generally saline – CO2 mixtures, but N2, CH4, H2O mixtures have also been recorded. Studies of fluid features related to exhumation have found that fluids may contribute to density changes and the initiation of partial melting during decompression, as well as the development of extensive vein systems. However, the preservation of geochemical signatures related to fluid processes occurring prior to high-P and ultrahigh-P metamorphism indicates that large-scale pervasive fluid flow systems, in general, do not operate at any stage during the exhumation history. Large-scale channelled fluid flow may have operated in detachment faults and shear zones related to exhumation, and this requires further study. The most significant role of fluids during exhumation appears to be their controlling influence on the preservation of high-P or ultrahigh-P rocks.

The role of partial melting on superplasticity of Si3N4p/Al-Cu-Mg composite

2000 ◽  
Vol 42 (5) ◽  
pp. 479-485 ◽  
Author(s):  
H.-G Jeong ◽  
K Hiraga ◽  
M Mabuchi ◽  
K Higashi
Keyword(s):  
Partial Melting
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