Equilibration conditions of Alpine type peridotites and associated rocks

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Institute for Study of the Earth"s Interior, Okayama University , Misasa, Japan
Peridotite -- Anal
Statementby Toshisuke Kawasaki.
SeriesTechnical report of ISEI. Ser. B -- no. 2., Technical report of ISEI -- no. 2.
ContributionsOkayama Daigaku. Chikyū Naibu Kenkyū Sentā.
The Physical Object
Pagination25 p. :
ID Numbers
Open LibraryOL15180083M

Although Alpine peridotites and basaltic lavas are widely associated in eugeosynclines and oceanic areas, their genetic ties are obscure. Three major characteristics of olivine-rich Alpine peridotite and dunite—relict cumulus textures, aggregated masses of chromitite, and intimate association with magnesium-rich gabbro — cannot be explained by partial melting of garnet peridotite to form Cited by: 8.

Alpine-type peridotites and associated pyroxenites are found as lenses in the continental crust in many different orogens. The reconstruction of the pressure–temperature (P–T) evolution of these rocks is, however, difficult or even impossible.

With geothermobarometry, usually one point on the overall P–T path can be by:   Intrusive peridotites predominate among alpine-type ultramafites in the Appalachians, and reflect genesis in a continental (ensialic) eugeosynclinal environment; ophiolites occur Cited by: The Almklovdalen peridotite massif is one of the Alpine-type ultramafic bodies which are scattered within the granitoid gneisses of the WGR of south-western Norway (Fig.1A).

The Proterozoic rocks of the WGR underwent subduction-related metamorphism during Caledonian continental colli-sion with local formation of high-pressure and ultrahigh-Cited by: Alpine-type peridotites and associated pyroxenites are found as lenses in the continental crust in many different orogens.

The reconstruction of the pressure–temperature (P – T) evolution of. Distribution of orogenic peridotites (In A called Alpine-type ultramafic rocks, in B garnet and chlorite peridotites, in C red stars) throughout the Scandinavian Caledonides. A: after Birtel ( We present an updated overview of the petrogenetic evolution of upper mantle peridotites exposed in the Alpine–Apennine ophiolites; the latter represent fragments of Jurassic oceanic lithosphere derived from the Ligurian–Piedmontese basin.

This synthesis is based on the results of recent multidisciplinary studies of these peridotite massifs in the Eastern, Central and Western Alps. Associated mafic rocks include eucrite and bojite at Wairere and feIdspathic peridotites, olivine gabbros, olivine-free gabbros, and troctolites in North Auckland.

Metasomatic changes have affected the chemistry and mineralogy of all rocks and have obscured. Skip to Main Content. Search term.

Details Equilibration conditions of Alpine type peridotites and associated rocks FB2

In the crustal rocks it is associated with mineral assemblages yielding LP‐HT conditions (°C to >°C, 3–6 kbar) achieved at circa 21 Ma. Such conditions are compatible with lithospheric stretching/thinning, responsible for and contemporaneous with the exhumation of the hot peridotites that acted as the main heat source.

The equilibration conditions of vv°C and GPa for garnet-spinel peridotites from the Central Schwarzwald Gneiss Complex (CSGC) are similar to those for eclogites of the Schwarzwald. Three varieties of alpine-type ultramafic rocks are distinguish in the Norwegian Caledonides associated Basal Gneiss Complex.

Type one rocks have primary (magmatic) olivine, clinopyroxene, orthopyroxene and chromite, and are partly or completely serpentinised. They are found exclusively in rocks of Cambro-Silurian age.

Thematic Article Petrology of the Yugu peridotites in the Gyeonggi Massif, South Korea: Implications for its origin and hydration process SHOJI ARAI,1*AKIHIRO TAMURA,1 SATOKO ISHIMARU,1 KAZUYUKI KADOSHIMA,1 YONG-IL LEE2 AND KEN-ICHIRO HISADA3 1Department of Earth Sciences, Kanazawa University, KanazawaJapan (email: [email protected]), 2School of Earth.

A major Alpine‐type peridotite located at Almklovdalen in the Western Gneiss Region of Norway was infiltrated by aqueous fluids at several stages during late Caledonian uplift and retrogressive metamorphism.

Download Equilibration conditions of Alpine type peridotites and associated rocks FB2

Re‐equilibration of the fluid phase topology took place by growth and dissolution processes driven by the excess surface energy. Experimental investigation of the petrogenesis of alpine-type peridotites and related rocks Ultramafic rocks located in orogenic belts have often been considered collectively as alpine-type, although they include a wide variety of mineral parageneses which have had a.

The hydration was associated with enrichment in light REE, resulting from either a slab-derived fluid or a fluid circulating in the crust. The mantle-wedge or abyssal peridotites were emplaced into the continental crust as the Yugu peridotite body during collision of continents to form a high-pressure metamorphic belt in the Gyeonggi Massif.

Description Equilibration conditions of Alpine type peridotites and associated rocks FB2

Recently developed ideas of global tectonics haye provided a new framework within which to consider the origin of alpine‐type peridotites. In plate theory, compressional zones associated with island arcs are considered to represent plate boundaries where oceanic lithosphere is subducted.

gin of alpine-type peridotites were questioned by Harry H. Hess (–), who had studied the occurrence of ultrama fi c rocks and serpentinites in. Henry J. Dick, Thomas Bullen, Chromian spinel as a petrogenetic indicator in abyssal and alpine-type peridotites and spatially associated lavas, Contributions to Mineralogy and Petrology, /BF, 86, 1, (), ().

Type I peridotites and associated volcanic rocks contain spinels with Cr#, and Type II peridotites and volcanics are a transitional group and contain spinels spanning the full range of spinel.

Peridotites from mid-ocean ridges record average f O 2 log units below the quartz-fayalite-magnetite (QFM) buffer (Bryndzia and Wood, ), while peridotites from the forearc region of subduction zones are more variable and encompass more oxidized conditions, with f O 2 as much as log units above the QFM buffer (QFM + The first type occurs associated with sulphides (mainly pyrite), either as inclusions (10–30 μm) or as sub-microscopic gold.

The second gold type consists of large gold grains (≥ μm) within the silicates (mostly quartz). LA-ICP-MS studies reveal that some gold and associated sulphide grains contain high values of Cl, Br, Na, and I.

Many of the peridotite xenoliths included in the San Quintin (Baja California Norte, Mexico) quaternary alkali-basalts have undergone a very intense shear deformation (deviatoric stresses up to GPa), hence a first-order classification into coarse-grained lherzolites and deformed peridotites (porphyroclastic and mosaic textures) has been applied.

All of these rocks show a very limited. A working framework for interpreting the geochemical characteristics of abyssal peridotites in the context of mantle melting, melt extraction and post-melting processes beneath mid-ocean ridges (modified from Niu, ).The mantle beneath an ocean ridge is conveniently considered as having two regions: the melting region between the solidus (P o) and the depth of melting cessation (P f) as a.

As rock textures reflect the physical conditions and the mechanisms of formation of the rocks, new approaches are used for improving texture analyses, both qualitatively and quantitatively. Pioneer work has recently boosted interest in fractal analysis for quantifying and correlating patterns.

The temperature conditions of re-equilibration entirely overlap with those of ductile deformation conditions (Rassios and Kostopoulos,Grieco et al., ). Pristine magmatic chromite compositions evolve via subsolidus re-equilibration during adiabatic cooling within a lithospheric slab “drifting” away from a spreading center.

Introduction. Pettersen () found a conspicuous rock type consisting mainly of orthopyroxene and magnesite near Lake Sagvandet, Troms, in the Caledonian mountain belt of northern Norway and named it assemblage orthopyroxene + dolomite (sagvandite-like) has also been recorded in Lyngenfjord area, 60 km north of the Lake Sagvandet, by Reitan and Geul,Randall.

Henry J. Dick, Thomas Bullen Chromian spinel as a petrogenetic indicator in abyssal and alpine-type peridotites and spatially associated lavas, Contributions to Mineralogy and Petrol no.1 1. Serpentinization greatly affects the physical and chemical properties of lithospheric mantle.

Here we address the fate of serpentinized peridotites and their influence over an ent. Occurrence and ClassificationFragments of the Earth's mantle are frequently transported to the surface via volcanic rocks that are dominantly alkaline in nature.

These fragments range up to sizes in excess of 1 m across. The term "mantle xenoliths" or "mantle nodules" is applied to all rock and mineral inclusions of presumed mantle derivation that are found within host rocks of volcanic origin.

Estimated equilibration conditions for a suite of Kaapvaal spinel and garnet mantle peridotite xenoliths, compared to a 40 mW/m 2 conductive geotherm [Pollack and Chapman, ].

The open blue squares denote spinel‐only peridotites. The open red circles represent low‐temperature garnet‐bearing peridotites.The preservation of ultra-high-pressure and super-reducing phases in the Neotethyan Luobusa ophiolite in Tibet suggests their deep origin near the mantle transition zone.

Dunite and harzburgite core samples from the Luobusa Scientific Drilling Project show supra-subduction zone geochemical signatures and equilibration temperatures of c. –°C. Olivine shows A- B- C- and E-type.The Alpine high-pressure metamorphism of LM rocks is heterogeneously recorded in metagabbros, peridotites and associated metasediments (Kienast & Pognante, ; Pelletier & Muentener, ).

Accord-ing to structural analysis, the western part of the southern boundary between the SLZ and the LM has been deformed since the early stages of Alpine.