Fluid evolution during high-pressure partial melting in the Austroalpine Ulten Zone, northern Italy

1996 ◽  
Vol 58 (3-4) ◽  
pp. 131-144 ◽  
Author(s):  
W. H�ller ◽  
G. Hoinkes
Keyword(s):  
High Pressure ◽  
Partial Melting ◽  
Northern Italy ◽  
Fluid Evolution

Mantle-derived dunite and lherzolite nodules from Ubekendt Ejland, west Greenland Tertiary province

1982 ◽  
Vol 46 (340) ◽  
pp. 329-336 ◽  
Author(s):  
Jørgen Gutzon Larsen
Keyword(s):  
High Pressure ◽  
Partial Melting ◽  
High Temperatures ◽  
Mantle Material ◽  
West Greenland ◽  
Coexisting Phases ◽  
Pressure Regime ◽  
Very High

AbstractScattered dunite and lherzolite nodules occur in one of the youngest basanitoid lavas on Ubekendt Ejland. They have protogranular to porphyroclastic textures. The dunites are composed of olivine (Fo93.2−91.9b), enstatite (En93.4−92.8) low in Al2O3 and CaO, and Cr-spinel (61-13% Cr2O3 and 3–55% Al2O3). A solitary lherzolite module has olivine (Fo94.7–94.1), enstatite (En94.7–94.2), Cr-rich spinel, Ti-phlogopite (11% TiO2), and hyalophane. Petrographic evidence suggests that the two latter minerals have not been introduced by magmatic injection from the host in spite of the refractory nature of the coexisting phases, and metasomatic processes prior to the last deformation are therefore indicated. Partial melting of such mantle material would presumably produce small amounts of alkaline liquids even at very high temperatures. Another lherzolite nodule from a lamprophyre dyke has minerals with lower Mg/(Mg + Fe) ratios which, together with its preserved igneous textures, suggest a high-pressure precipitate. The lowest well-esablished equilibrium temperatures of 700–830°C for both dunites and lherzolites indicate a pressure regime of 12-17 kbar, according to the oceanic geotherm, whereas unrealistically high pressure (20–5 kbar) are suggested using the continental shield geotherm.

High-pressure experimental studies on the origin of anorthosite

1969 ◽  
Vol 6 (3) ◽  
pp. 427-440 ◽  
Author(s):  
Trevor H. Green
Keyword(s):  
High Pressure ◽  
Partial Melting ◽  
Lower Crust ◽  
Experimental Studies ◽  
Quartz Diorite ◽  
Main Phase ◽  
Large Field ◽  
High Alumina ◽  
High Alumina Basalt ◽  
Rock Types

Experimental crystallization of anhydrous synthetic quartz diorite (≈andesite), gabbroic anorthosite, and high-alumina basalt has been conducted in their respective partial melting fields at high pressure. The quartz diorite composition shows a large field of crystallization of plagioclase from 0–13.5 kb, together with subordinate amounts of orthopyroxene and clinopyroxene and minor opaque minerals. In the gabbroic anorthosite, plagioclase is the main phase crystallizing from 0–22.5 kb, but at higher pressure it is replaced by aluminous clinopyroxene. Aluminous clinopyroxene is the main phase crystallizing from the high-alumina basalt from 9–18 kb and is joined by plagioclase at lower temperatures. At higher pressure it is joined by garnet. The albite content of the liquidus and near-liquidus plagioclase increases markedly with increasing pressure in each of the three compositions.The results for the high-alumina basalt and gabbroic anorthosite compositions preclude any major trends towards alumina enrichment and derivation of anorthositic plutons at crustal or upper mantle depths under anhydrous conditions. However, the results for the quartz diorite suggest that anorthositic complexes may form as a crystalline residuum from the partial melting of a lower crust of overall andesitic composition or from fractional crystallization of an andesitic magma. In either case a large separation of plagioclase crystals occurs (andesine – acid labradorite composition at lower crustal pressures), together with subordinate pyroxenes and ore minerals. Under appropriate temperature conditions separation of crystals and liquid by a filter-pressing mechanism during deformation may result in the genesis of igneous complexes containing rock types ranging in composition from gabbro through gabbroic anorthosite to anorthosite, together with associated acid rocks. The acid rocks need not necessarily remain spatially associated with the refractory gabbroic anorthosite and anorthosite. Where these processes have operated in the crust, anorthositic rocks may be left as the main component of the lower crust, while the low melting acidic fraction has intruded to higher levels.

scholarly journals High-pressure Partial Melting of Mafic Lithologies in the Mantle

2004 ◽  
Vol 45 (12) ◽  
pp. 2407-2422 ◽  
Author(s):  
T. KOGISO
Keyword(s):  
High Pressure ◽  
Partial Melting

scholarly journals High-pressure meta-ophiolite boulders and cobbles from northern Italy as possible raw-material sources for “greenstone” prehistoric tools: petrography and archaeological assessment

2019 ◽  
Vol 31 (5-6) ◽  
pp. 905-917 ◽  
Author(s):  
Benjámin Váczi ◽  
György Szakmány ◽  
Elisabetta Starnini ◽  
Zsolt Kasztovszky ◽  
Zsolt Bendő ◽  
...  
Keyword(s):  
High Pressure ◽  
Northern Italy ◽  
Raw Material ◽  
Material Sources

Behavior of barium isotopes during high-pressure metamorphism and fluid evolution

2021 ◽  
Vol 575 ◽  
pp. 117176
Author(s):  
Xiao-Feng Gu ◽  
Shun Guo ◽  
Hui-Min Yu ◽  
Juan Xu ◽  
Fang Huang
Keyword(s):  
High Pressure ◽  
High Pressure Metamorphism ◽  
Fluid Evolution

High-pressure partial melting and melt loss in felsic granulites in the Kutná Hora complex, Bohemian Massif (Czech Republic)

Lithos ◽  
2011 ◽  
Vol 125 (1-2) ◽  
pp. 641-658 ◽  
Author(s):  
Radmila Nahodilová ◽  
Shah Wali Faryad ◽  
David Dolejš ◽  
Peter Tropper ◽  
Jürgen Konzett
Keyword(s):  
High Pressure ◽  
Czech Republic ◽  
Partial Melting ◽  
Bohemian Massif
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