Olivine-mica pyroxenite xenoliths from northern Tanzania: metasomatic products of upper-mantle peridotite

1992 ◽  
Vol 50 (1-2) ◽  
pp. 131-142 ◽  
Author(s):  
J.B. Dawson ◽  
J.V. Smith
Keyword(s):  
Upper Mantle ◽  
Mantle Peridotite ◽  
Northern Tanzania

Enrichment of upper mantle peridotite: petrological, trace element and isotopic evidence in xenoliths from SE China

2003 ◽  
Vol 198 (3-4) ◽  
pp. 163-188 ◽  
Author(s):  
Xisheng Xu ◽  
Suzanne Y O'Reilly ◽  
W.L Griffin ◽  
Xinmin Zhou
Keyword(s):  
Trace Element ◽  
Upper Mantle ◽  
Mantle Peridotite ◽  
Isotopic Evidence ◽  
Se China

scholarly journals Experimental study of formation of chromian priderite and yimengite as products of modal mantle metasomatism

2019 ◽  
Vol 486 (6) ◽  
pp. 709-713
Author(s):  
V. G. Butvina ◽  
S. S. Vorobey ◽  
O. G. Safonov ◽  
D. A. Varlamov ◽  
G. V. Bondarenko ◽  
...  
Keyword(s):  
Experimental Study ◽  
Upper Mantle ◽  
Mantle Peridotite ◽  
Mantle Metasomatism ◽  
Mantle Minerals ◽  
Silicate Inclusions ◽  
Chromium Spinel ◽  
Series Of Experiments ◽  
Indicator Minerals ◽  
The Relationship

The article presents the data of a series of experiments on the synthesis of exotic titanates (priderite and yimengite) as a result of the reproduction of metasomatic conditions of transformation of mantle minerals (chromite, ilmenite). It was first synthesized chromian priderite not containing Ba. The experiments showed the possibility of crystallization of this mineral as a reaction product of high-chromium spinel and rutile with potassium aqueous carbonate fluid (melt) in the upper mantle. In particular, the obtained experimental data allow us to interpret the relationship between K-Cr-priderite and carbonate-silicate inclusions in chromites of Bohemian garnet peridotites. In the experimental study of the reaction of chromite and ilmenite with aqueous potassium-carbonate fluid (melt) obtained both phases of titanates (priderite and yimengite) - indicator minerals, mantle metasomatism, which directly confirms the possibility of formation of yimengite and K-Cr-priderite and other titanates, the result of mantle metasomatism of upper mantle peridotite under conditions of the highest activity of potassium.

scholarly journals The emplacement of peridotites and associated oceanic rocks from the Lizard Complex, southwest England

2002 ◽  
Vol 139 (1) ◽  
pp. 27-45 ◽  
Author(s):  
C. A. COOK ◽  
R. E. HOLDSWORTH ◽  
M. T. STYLES
Keyword(s):  
Upper Mantle ◽  
Mantle Peridotite ◽  
Temperature Deformation ◽  
Crustal Rocks ◽  
Kinematic Indicators ◽  
Pull Apart Basin ◽  
Mantle Peridotites ◽  
Mineral Assemblages ◽  
Metamorphic Assemblage ◽  
Oceanic Rocks

Upper mantle peridotites and associated oceanic rocks from the Lizard Complex, southwest England, preserve evidence for a multistage geological history. Steeply dipping pre-emplacement fabrics record high-temperature (900–1100°C) shearing and exhumation of the mantle peridotites apparently formed during localized NE–SW rifting in a pull-apart basin setting (c. 400–390 Ma). Associated oceanic rocks (Landewednack amphibolites) preserve a pre-emplacement prograde brown amphibole-bearing metamorphic assemblage and steeply dipping fabric thought to have formed as the newly formed oceanic crust was juxtaposed with newly exhumed hot mantle peridotite during NE–SW rifting. In both the peridotites and Landewednack amphibolites, steep pre-emplacement structures are cross-cut by low-angle mylonitic fabrics thought to have formed during the initial phases of emplacement of mantle over crustal rocks in a partially intra-oceanic setting (c. 390–375 Ma). The fabrics in peridotites and amphibolites exhibit retrograde mineral assemblages (c. 500–800°C), with the amphibolites preserving two superimposed assemblages, green amphibole + titanite and colourless magnesio-hornblende, respectively, that are thought to record progressive down-temperature deformation during thrusting. Emplacement-related structures in both the basal peridotites and amphibolites consistently dip at low to moderate angles NW, with down-dip lineations and kinematic indicators showing consistent top-to-the-NW senses of shear. Syn-emplacement magmatism is recorded by intrusions of foliated Kennack Gneiss. Anastomosing serpentine-filled faults mark many existing low-angle contacts between the peridotites and Landewednack amphibolites and appear to represent the final, lowest-temperature (< 250°C) stages of emplacement (c. 370 Ma). This study shows that ‘dynamothermal aureoles’ in ophiolites may preserve evidence for tectonothermal events that pre-date thrust emplacement.

Upper-mantle amphiboles: a review

1982 ◽  
Vol 45 (337) ◽  
pp. 35-46 ◽  
Author(s):  
J. B. Dawson ◽  
J. V. Smith
Keyword(s):  
Upper Mantle ◽  
Water Storage ◽  
Mantle Peridotite ◽  
Chemical Data ◽  
Storage Site ◽  
Relative Paucity

AbstractTextural and chemical data are reviewed for amphiboles occurring in Cr-diopside series and Al-augite series xenoliths; as megacrysts in a variety of igneous environments; and also as minor phases in tectonic slices of upper-mantle peridotite. New data are given for pargasite and associated phases in a lherzolite from Tanzania and in kelyphite replacing garnet in a S. African kimberlite xenolith. It is concluded that only pargasites and titaniferous pargasites occurring in Cr-diopside series blocks have formed under upper-mantle conditions. Although amphibole is present in the upper mantle, as suggested by Oxburgh (1964), its relative paucity suggests it is not a major alkali and water storage site; phlogopite is a more likely candidate, particularly in the deeper parts of the upper mantle.

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