Molybdenite Re–Os dating of biotite dehydration melting in the Rogaland high-temperature granulites, S Norway

2003 ◽  
Vol 208 (3-4) ◽  
pp. 181-195 ◽  
Author(s):  
Bernard Bingen ◽  
Holly Stein
Keyword(s):  
High Temperature ◽  
Dehydration Melting ◽  
Biotite Dehydration Melting

scholarly journals Petrogenesis of Mesozoic, Peraluminous Granites in the Lamoille Canyon Area, Ruby Mountains, Nevada, USA

2003 ◽  
Vol 44 (4) ◽  
pp. 713-732 ◽  
Author(s):  
Sang-Yun Lee ◽  
Calvin G. Barnes ◽  
Arthur W. Snoke ◽  
Keith A. Howard ◽  
Carol D. Frost
Keyword(s):  
Great Basin ◽  
Late Cretaceous ◽  
Heat Input ◽  
Crustal Thickening ◽  
Dehydration Melting ◽  
Granitic Gneiss ◽  
Peraluminous Granites ◽  
Ruby Mountains ◽  
Sevier Orogeny ◽  
Biotite Dehydration Melting

Abstract Two groups of closely associated, peraluminous, two-mica granitic gneiss were identified in the area. The older, sparsely distributed unit is equigranular (EG) with initial εNd ∼ − 8·8 and initial 87Sr/86Sr ∼0·7098. Its age is uncertain. The younger unit is Late Cretaceous (∼80 Ma), pegmatitic, and sillimanite-bearing (KPG), with εNd from −15·8 to −17·3 and initial 87Sr/86Sr from 0·7157 to 0·7198. The concentrations of Fe, Mg, Na, Ca, Sr, V, Zr, Zn and Hf are higher, and K, Rb and Th are lower in the EG. Major- and trace-element models indicate that the KPG was derived by muscovite dehydration melting (<35 km depth) of Neoproterozoic metapelitic rocks that are widespread in the eastern Great Basin. The models are broadly consistent with anatexis of crust tectonically thickened during the Sevier orogeny; no mantle mass or heat contribution was necessary. As such, this unit represents one crustal end-member of regional Late Cretaceous peraluminous granites. The EG was produced by biotite dehydration melting at greater depths, with garnet stable in the residue. The source of the EG was probably Paleoproterozoic metagraywacke. Because EG magmatism probably pre-dated Late Cretaceous crustal thickening, it required heat input from the mantle or from mantle-derived magma.

Very high temperature, moderate pressure metamorphism in the New Russia gneiss complex, northeastern Adirondack Highlands, metamorphic aureole to the Marcy anorthosite

1999 ◽  
Vol 36 (1) ◽  
pp. 1-13 ◽  
Author(s):  
J Alcock ◽  
Peter Muller
Keyword(s):  
New York ◽  
High Temperature ◽  
Moderate Pressure ◽  
Dehydration Melting ◽  
Eastern Margin ◽  
Gneiss Complex ◽  
Anorthosite Massif ◽  
Metamorphic Gradient ◽  
High Temperature Metamorphism ◽  
Very High

The New Russia gneiss complex in the northeastern Adirondack Highlands of New York includes meta-anorthosite gneiss and anatectic gneiss derived from metagabbro, mangerite, and charnockite. Metamorphic conditions during anatexis (850-950°C, highest near the anorthosite, with pressure ~750 MPa) are inferred from minerals and textures produced by dehydration melting of pargasitic hornblende and from ternary feldspar in anatectic segregations. The complex abuts and is crosscut by the eastern margin of the ~1130 Ma Marcy anorthosite massif. The crosscutting contact, the presence of meta-anorthosite gneiss within the complex and undeformed meta-anorthosite in the massif, and the occurrence of deformed and undeformed anatectic segregations within the New Russia gneisses indicate an approximate synchroneity of penetrative deformation, very high temperature metamorphism, and emplacement of anorthosite with both intrusion and anatexis outlasting deformation. The position of the New Russia gneisses, the metamorphic gradient within them, and the contemporaneity of anatexis with intrusion of anorthosite imply that the complex is the metamorphic aureole of the Marcy anorthosite.

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

Geology ◽  
2021 ◽  
Author(s):  
Panlao Zhao ◽  
Xu Chu ◽  
Anthony E. Williams-Jones ◽  
Jingwen Mao ◽  
Shunda Yuan
Keyword(s):  
Partial Melting ◽  
Geochemical Data ◽  
Dehydration Melting ◽  
Metasedimentary Rocks ◽  
Partial Melt ◽  
Tin Deposits ◽  
Higher Temperature ◽  
Biotite Dehydration Melting ◽  
Highly Evolved

Most tungsten (W) and tin (Sn) deposits are associated with highly evolved granites derived from the anatexis of metasedimentary rocks. They are commonly separated in both space and time, and in the rare cases where the W and Sn mineralization are part of a single deposit, the two metals are temporally separate. The factors controlling this behavior, however, are not well understood. Our compilation of whole-rock geochemical data for W- and Sn-related granites in major W-Sn metallogenic belts shows that the Sn-related granites are generally the products of higher-temperature partial melting (~800 °C) than the W-related granites (~750 °C). Thermodynamic modeling of partial melting and metal partitioning shows that W is incorporated into the magma formed during low-temperature muscovite-dehydration melting, whereas most of the Sn is released into the magma at a higher temperature during biotite-dehydration melting; the Sn of the magma may be increased significantly if melt is extracted prior to biotite melting. At the same degree of partial melting, the concentrations of the two metals in the partial melt are controlled by their concentration in the protolith. Thus, the nature of the protolith and the melting temperature and subsequent evolution of the magma all influence the metallogenic potential of a magma and, in combination, helped control the spatial and temporal segregation of W and Sn deposits in all major W-Sn metallogenic belts.

Petrological evidence for crustal thickening and extension in the Serre granulite terrane (Calabria, southern Italy)

2006 ◽  
Vol 143 (2) ◽  
pp. 145-163 ◽  
Author(s):  
PASQUALE ACQUAFREDDA ◽  
ANNAMARIA FORNELLI ◽  
ANTONIO PAGLIONICO ◽  
GIUSEPPE PICCARRETA
Keyword(s):  
High Temperature ◽  
Phase Equilibria ◽  
Southern Italy ◽  
Crustal Thickening ◽  
Stability Field ◽  
Low Grade ◽  
Dehydration Melting ◽  
Prograde Metamorphism ◽  
Isothermal Decompression ◽  
The Stability

The paper presents the metamorphic trajectory recorded by metapelitic migmatites of the upper part of the Hercynian lower continental crust of the Serre (southern Calabria, Italy). The relict minerals, reaction textures and phase equilibria define a clockwise P–T path. The prograde metamorphism from temperature of about 500°C and pressure of 4–5 kbar to T<700°C and P∼8 kbar stabilized the assemblage Grt+Ky+Bt+Ms(Si/11ox=3.26–3.29) in the uppermost metapelites of the profile. Progressive heating led to H2O-fluxed and dehydration melting first of Ms, then of Bt at T<700°C in the stability field of sillimanite. This process was followed by nearly isothermal decompression producing additional melt with a transition from Grt to a Grt+Crd stability field. Further decompression caused the formation of Crd-corona around garnet. Nearly isobaric cooling led to rehydration and retrogression across the stability field of andalusite up to the stability field of kyanite. The lowermost metapelites of the studied profile have lost most of the memory of the prograde P–T path; they record decompression and cooling. High-temperature mylonites occur in which boudinage, elongation and pull-aparts characterize the porphyroclasts. The pull-aparts in the high-T mylonites are filled with low-P minerals (Crd+Spl). The Hercynian metamorphic trajectory and the microtextures are consistent with crustal thickening and subsequent extensional regime. During extension, an important tectonic denudation probably caused the isothermal decompression. Extension also occurred in post-Hercynian times as documented by pull-aparts in sillimanite porphyroclasts filled with chloritoid within a low-grade mylonite.

Early Oligocene partial melting via biotite dehydration melting and prolonged low-pressure–low-temperature metamorphism of the upper High Himalaya Crystalline Sequence in the far east of Nepal

2018 ◽  
Vol 481 (1) ◽  
pp. 147-173 ◽  
Author(s):  
T. Imayama ◽  
T. Takeshita ◽  
K. Yi ◽  
M. Fukuyama
Keyword(s):  
Low Temperature ◽  
Partial Melting ◽  
Channel Flow ◽  
Far East ◽  
Low Pressure ◽  
Dehydration Melting ◽  
Early Oligocene ◽  
The Far East ◽  
Supplementary Material ◽  
Biotite Dehydration Melting

AbstractEarly Oligocene partial melting and prolonged low-pressure–low-temperature (low-P/T) metamorphism were investigated in migmatites and orthogneisses from the upper High Himalaya Crystalline Sequence (HHCS) in the far east of Nepal. The migmatites were formed by biotite dehydration melting at c. 800°C from 33 to 25 Ma. Cordierite was only produced at shallow crustal levels at pressures <6 kbar. After Early Oligocene partial melting, the low-P/T metamorphism continued until 17 Ma during exhumation of the cordierite-bearing migmatites. Early Oligocene biotite dehydration melting in the upper HHCS occurred at different times and locations from the Early Miocene muscovite dehydration melting in the underlying HHCS and the metamorphic discontinuity was accompanied by thrusting of the High Himalayan Discontinuity at c. 27–19 Ma. Pervasive partial melting and prolonged low-P/T metamorphism in the upper HHCS is more compatible with a lateral southwards channel flow of the upper HHCS along the High Himalayan Discontinuity, whereas current channel flow models explaining the exhumation of the HHCS as driven only by the coupled activity of the Main Central Thrust and South Tibetan Detachment have faced difficulties in explaining the timing of the low-P/T metamorphism observed in the upper HHCS.Supplementary material: The representative cordierite compositions from the cordierite migmatites, the far east of Nepal are available at https://doi.org/10.6084/m9.figshare.c.4068815

Influence of Thermo-Mechanical Processing on the Microstructure of Beryllia Dispersed Nickel Alloys

1973 ◽  
Vol 31 ◽  
pp. 184-185
Author(s):  
M.S. Grewal ◽  
S.A. Sastri ◽  
N.J. Grant
Keyword(s):  
High Temperature ◽  
Nickel Alloys ◽  
Thermomechanical Processing ◽  
Cold Work ◽  
High Temperature Strength ◽  
Strengthening Effect ◽  
Mechanical Processing ◽  
Uniform Dispersion ◽  
Oxide Particles ◽  
Nickel Base

Currently there is a great interest in developing nickel base alloys with fine and uniform dispersion of stable oxide particles, for high temperature applications. It is well known that the high temperature strength and stability of an oxide dispersed alloy can be greatly improved by appropriate thermomechanical processing, but the mechanism of this strengthening effect is not well understood. This investigation was undertaken to study the dislocation substructures formed in beryllia dispersed nickel alloys as a function of cold work both with and without intermediate anneals. Two alloys, one Ni-lv/oBeo and other Ni-4.5Mo-30Co-2v/oBeo were investigated. The influence of the substructures produced by Thermo-Mechanical Processing (TMP) on the high temperature creep properties of these alloys was also evaluated.

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