Role of fractional crystallization and partial melting in the generation of intermediate and acidic magmas of the Andaman Island Ophiolite suite of India

2021 ◽  
Author(s):  
Ashima Saikia ◽  
Salim Akhtar ◽  
Priyanka Negi
Keyword(s):  
Partial Melting ◽  
Fractional Crystallization ◽  
Andaman Island ◽  
Ophiolite Suite

scholarly journals Supplemental Material: The role of phyllosilicate partial melting in segregating tungsten and tin deposits in W-Sn metallogenic provinces

2021 ◽  
Author(s):  
Panlao Zhao ◽  
Shunda Yuan ◽  
et al.
Keyword(s):  
Partial Melting ◽  
Fractional Crystallization ◽  
Modeling Method ◽  
Tin Deposits

Partial melting and fractional crystallization modeling method, and explanation of supplemental figures.<br>

scholarly journals Supplemental Material: The role of phyllosilicate partial melting in segregating tungsten and tin deposits in W-Sn metallogenic provinces

2021 ◽  
Author(s):  
Panlao Zhao ◽  
Shunda Yuan ◽  
et al.
Keyword(s):  
Partial Melting ◽  
Fractional Crystallization ◽  
Modeling Method ◽  
Tin Deposits

Partial melting and fractional crystallization modeling method, and explanation of supplemental figures.<br>

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.

scholarly journals Geochemistry of Garga-Sarali intrusive granitoids (central domain of the central African fold belt in Cameroon): petrological implication

2020 ◽  
Vol 8 (1) ◽  
pp. 33
Author(s):  
Daama Isaac ◽  
Mbowou Gbambie Isaac Bertrand ◽  
Yamgouot Ngounouno Fadimatou ◽  
Ntoumbe Mama ◽  
Ngounouno Ismaïla
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Partial Melting ◽  
Fractional Crystallization ◽  
Coarse Grained ◽  
Geochemical Analysis ◽  
Fold Belt ◽  
Volcanic Arcs ◽  
Fine Grained ◽  
Incompatible Elements

The Garga-Sarali granitoids outcrop in form of large slabs and undistorted large blocks, into a schisto-gneissic basement. These rocks contain mainly muscovite and microcline, followed by K-feldspar, quartz, biotite, pyroxene, zircon and oxides, with coarse-grained to fine-grained textures. Geochemical analysis show that it belongs to differentiated rocks group (granodiorite-granite) with high SiO2 (up to 72 wt%) contents. Their genesis was made from a process of partial melting and fractional crystallization. These rocks are classified as belonging to I- and S-Type, meta-peraluminous, shoshonitic granites; belonging to the domain of volcanic arcs. The rare earth elements patterns suggest a source enriched of incompatible elements. The Nb-Ta and Ti negative anomalies from the multi-element patterns are characteristics of the subduction domains.  

scholarly journals Lithogeochemistry of the Mid-Ocean Ridge Basalts near the Fossil Ridge of the Southwest Sub-Basin, South China Sea

Minerals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 465 ◽  
Author(s):  
Kai Sun ◽  
Tao Wu ◽  
Xuesong Liu ◽  
Xue-Gang Chen ◽  
Chun-Feng Li
Keyword(s):  
South China Sea ◽  
Partial Melting ◽  
Fractional Crystallization ◽  
South China ◽  
Spreading Rate ◽  
Tholeiitic Basalt ◽  
Spinel Peridotite ◽  
China Sea ◽  
Mid Ocean Ridge ◽  
Ocean Ridge

Mid-ocean ridge basalts (MORB) in the South China Sea (SCS) record deep crust-mantle processes during seafloor spreading. We conducted a petrological and geochemical study on the MORBs obtained from the southwest sub-basin of the SCS at site U1433 and U1434 of the International Ocean Discovery Program (IODP) Expedition 349. Results show that MORBs at IODP site U1433 and U1434 are unaffected by seawater alteration, and all U1433 and the bulk of U1434 rocks belong to the sub-alkaline low-potassium tholeiitic basalt series. Samples collected from site U1433 and U1434 are enriched mid-ocean ridge basalts (E-MORBs), and the U1434 basalts are more enriched in incompatible elements than the U1433 samples. The SCS MORBs have mainly undergone the fractional crystallization of olivine, accompanied by the relatively weak fractional crystallization of plagioclase and clinopyroxene during magma evolution. The magma of both sites might be mainly produced by the high-degree partial melting of spinel peridotite at low pressures. The degree of partial melting at site U1434 was lower than at U1433, ascribed to the relatively lower spreading rate. The magmatic source of the southwest sub-basin basalts may be contaminated by lower continental crust and contributed by recycled oceanic crust component during the opening of the SCS.

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