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The Yoncayolu Metamorphic Rocks (YMR), exposed in the Sakarya zone (Erzincan, NE Turkey), consists mainly of greenschist rocks which are chlorite schists, muscovite-chlorite schists, metabasic rocks and lesser extent of pyhllites and calc-schists. All YMR are fine-grained, weakly foliated and often cut by quartz veins. The common mineral assemblage is chlorite+albite+epidote+quartz ± clinozoisite ± actinolite ± opaques. Geochemically, protoliths of the YMR resemble calc-alkaline volcanic arc rocks. The YMR have high contents of large ion lithophile elements (LILEs) and low contents of high field strength elements (HFSEs) similar to mid-ocean ridge basalt (MORB). (La/Lu)CN values are between 0.26 and 6.16. The REE patterns show slight or no Eu anomalies (EuCN/Eu* of 0.48 to 1.13), suggesting minor plagioglase fractionation. 40Ar-39Ar dating on plagioclases from the metabasic samples of the YMR gave ages of 100.8 ± 3.4 Ma (Albian) and 94.1 ± 3.3 Ma (Cenomanian), suggesting that metamorphism was related to the closure of the Neo-Tethyan Ocean. Metamorphism took place during subduction of the Neo- Tethyan Ocean between ~ 90 –70 Ma. Chlorite geothermometry yielded a temperature of 320 – 350 °C and a pressure around 4 kbar. All these findings lend support for greenschist facies metamorphic conditions during the formation of the YMR.

This thesis attempts to interpret the metamorphic condition and fluid composition experienced by metacarbonates on Utö, located in the south-eastern parts of the Stockholm archipelago. Utö is a part of the Svecofennian domain, and the area Bergslagen, that has hosted several mines over the last millennia. The bedrock in this area has been dated by the U-Pb technique to 1.90-1.87 Ga, placing it in the Paleoproterozoic era (Allen et al. 1996, Lundström et al. 1998). The rocks, of the studied area on the island of Utö, are mainly metacarbonates with a varying purity and thin layers of volcanic ash. These rocks become more felsic towards the north-western coast as the layers of felsic ash become more dominant. To determine the P-T-XCO2 of metamorphism, metacarbonates were examined, in the field, in thin sections and mineral chemistry was determined by SEM analysis. Three samples were collected along a 1km transect, along which the assemblage calcite + dolomite + quartz + tremolite + diopside was observed. Petrographic and SEM analysis were performed to gather chemical data from coexisting calcite and dolomite in order to calculate temperature using the calcite-dolomite geothermometer. Chemical data from the SEM analysis were also run with AX and THERMOCALC together with pressure data received from a study by Engström (2011) of the adjacent island, Persholmen, to generate a T- XCO2 diagram. Pressure was estimated to 3.1 +/- 1.3 kbars, temperature calculated to 442°C 30°C and XCO2 to range from 0,00067-0,0038 with the standard deviation taken in to account. These results record equilibration with a CO2-bearing hydrous fluid at greenschist facies conditions. Metamorphic map of Sweden

Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-27T11:24:38Z No. of bitstreams: 0Bitstream added on 2014-05-27T14:35:44Z : No. of bitstreams: 1 2-s2.0-77951069166.pdf: 718441 bytes, checksum: 8eb48304099737179873b54a458b7597 (MD5) Made available in DSpace on 2014-05-27T11:24:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-03-01 Metaultramafic bodies tectonically emplaced within the metasedimentary sequence of the Araxá Group are associated with an ophiolitic melange in southeast Goiás. In the region of Crominia - Mairipotaba, they occur as lenticular bodies aligned E-W. Cumulate textures and geochemical data indicate that the parent rocks had harzburgitic to dunitic compositions. Relicts of primary crystals of olivine and orthopyroxene are suggestive of amphibolite facies metamorphic re-equilibration fabrics, even though the paragenesis and mineral associations of these metaultramafic rocks are typical of greenschist facies (T < 550°C and P = 5.5 kbar). The chromitites exhibit massive to breccioid structure and pull-apart texture, with chromite crystals around 0.5 mm in size. Chromite concentrations in the chromitite levels reach 70 to 85% by volume of the rock. The crystals are dispersed in the matrix, which is composed essentially of serpentine, and subordinately of chlorite and talc. The textures and geochemical data (Cr 2O 3 x TiO 2 and Mg x Cr ratios present in the chromitite) are similar to those observed in ophiolitic complexes. Hence, they correspond to allochthonous bodies (Alpine type) associated with an ophiolitic mélange. Departamento de Petrologia e Metalogenia UNESP, Av. 24-A 1.515, CEP 13506-900, Rio Claro, SP Pós-graduação em Geologia Regional Instituto de Geociências e Ciências Exatas UNESP, Rio Claro, SP Departamento de Mineralogia e Geotectônica Instituto de Geociências USP, São Paulo, SP Departamento de Petrologia e Metalogenia UNESP, Av. 24-A 1.515, CEP 13506-900, Rio Claro, SP Pós-graduação em Geologia Regional Instituto de Geociências e Ciências Exatas UNESP, Rio Claro, SP

Petrography, mineralogy and geochemistry of rodingites of the Piedmont ophiolite nappe, Western Alps (Italy). The focus of this research has been the estimation of the timing of the rodingitization process relative to the metamorphic evolution of the ophiolitic remnants in the Western Alps. Four rodingitic sites were studied: Perrères (Valtournanche, Val d'Aoste), Monte Avic (Val d'Aoste) and, in the Voltri Massif, Vara and La Carta. All of these occur in a high pressure – low temperature metamorphic context, retromorphosed to greenschist facies. For comparison, two samples from the mid-Atlantic fractures zones were examined. The petrographic study of the rodingites has revealed a primary paragenesis and a rodingitic paragenesis. The primary paragenesis comprises relict magmatic clinopyroxene (clinopyroxene 1) transformed into diopside, apatite and oxides (ilmenite and/or magnetite and/or chromite). The rodingitic paragenesis consists of garnet (grossular-alamandine and/or grossular-andradite), diopsidic clinopyroxene (clinopyroxene 2), chlorite (clinochlore), and epidote or vesuvianite. In the Voltri Massif, sphene, albite, amphiboles and carbonates are accessory minerals. The narrow rim of chloritoschist located between the rodingitic dyke and the surrounding serpentinite constitutes the only observable zonation. Epidote and vesuvianite represent the last phases of the rodingitic transformation process. A crystallisation – deformation study of the Perrères site, together with data on fluid inclusions in one sample from Vara, have shown that the garnet crystallized under greenschist facies conditions (i.e. 2 to 3 kbars and 360 to 400°C). Study of the rare earth elements (REE) and trace elements in rocks and individual minerals has led to the establishment of a model with three phases. The first phase is characterized by the clinopyroxene 1 which retained its REE-magmatic signature (isochemical); the second phase is represented by the garnet which is in equilibrium with clinopyroxene 2; while the third phase is marked by the appearance of epidote which seems to have grown at the expense of garnet. This study has also shown that the hypothesis which envisages an eclogitic protolith cannot be confirmed. Finally, the comparison between rodingites and the gabbroic samples collected by drilling in mid-Atlantic zones (Barling et al., 1997) suggests that the protoliths for the Perrères and Monte Avic rodingites were probably troctolitic cumulates and gabbros sensu stricto, while the Voltri Massif rodingites had an oxide-rich gabbro protolith. The initial liquids would have been of MORB-type , wich fit with the geochemical data of the alpine ophiolites. (SC - Sciences) -- UCL, 2001

The six exposures of the Upper tectonic Unit of the Cycladic Massif occurring on the island of Tinos are shown to comprise a metamorphosed dismembered ophiolite complex. The common stratigraphic section consisting of tens-of-metres- thick tectonic slices of mafic phyllites overlain by serpentinites and gabbros is considered to have been derived by a combination of thrusting during obduction and subsequent attenuation by low-angle normal faults. All rock types show evidence of a phase of regional greenschist-facies metamorphism, which in the case of the phyllites is accompanied by penetrative deformation. The greenschist-facies metamorphism in gabbros is preceded by high temperature sea-floor amphibolite-facies alteration, whereas in the serpentinites, the antigorite + forsterite greenschist-facies assemblage overprinted an earlier low temperature lizardite serpentinite. Trace element patterns of the mafic phyllites and a harzburgitic origin of meta-serpentinites suggest a supra subduction zone (SSZ) affinity for the ophiolitic suite. ρ18O values of phyllites, gabbros and serpentinites range from 6 to 15%o. Model calculations indicate that such values are consistent with low temperature (50–200°C) alteration of parent rocks by sea-water at varying water/rock ratios. This would agree with the early low temperature mineralogy of the serpentinites, but the early high temperature alteration of the gabbros would require the presence of18O-enriched sea-water.The following overall history is suggested for Tinos ophiolitic slices. (1) Oceanic crust was generated at a supra-subduction zone spreading centre with high temperature alteration of gabbros. (2) Tectonic disturbance (its early hot stages recorded in an amphibolitic shear zone at the base of serpentinites) brought the already cooled ultramafics into direct contact with sea-water and caused low-Tserpentinization. (3) Tectonism after cooling involved thrusting which caused repetition and inversion of the original order of the oceanic suite. (4) Regional metamorphism of all the ophiolite components at greenschist-facies conditions (−450°C) overprinted the early alteration mineralogy. It was probably induced by continued thrusting and piling up of nappes. The Tinos ophiolite, dated as late Cretaceous and genetically related to other low pressure rock-units of the same age in the Aegean, differs in age and degree of dismemberment and metamorphism from ophiolites in mainland Greece.

The basic and ultrabasic rocks from Mina Salamanca district and Los Gateados area are metamorphosed in epidote-amphibolite facies, and locally, in greenschist facies conditions. The green chist facies assemblages develop associated to carbonate (± .quartz ) veins in the amphibolites and to talc + magnesite assemblages in serpentinites . In the latter case, the fluids dissolved a primary, disseminated sulfide mineralization and gave rise to a massive ore along a fault zone in Mina Salamanca district

The basic and ultrabasic rocks from Mina Salamanca district and Los Gateados area are metamorphosed in epidote-amphibolite facies, and locally, in greenschist facies conditions. The green chist facies assemblages develop associated to carbonate (± .quartz ) veins in the amphibolites and to talc + magnesite assemblages in serpentinites . In the latter case, the fluids dissolved a primary, disseminated sulfide mineralization and gave rise to a massive ore along a fault zone in Mina Salamanca district, Las rocas básicas y ultrabásicas del distrito de Mina de Salamanca y el área de Los Gateados han sido metamorfoseadas en facies de epidota-anfibolitas, y localmente, en condiciones de facies de esquistos. Las asociaciones de facies de esquistos desarrollan venas asociadas al carbonato (± .cuarzo) en las anfibolitas y a asociaciones de talco + magnesita en las serpentinitas. En este último caso, los fluidos disolvieron una mineralización primaria diseminada de sulfuro y dieron lugar a una mena masiva en torno a una zona de falla en el distrito de Mina Salamanca.

Spilites, altered diabases and meta-basalts from Hruskovec quarry on Mt. Kalnik form part of a complex sequence of extrusive rocks. They are the result of several successive extrusions of basaltic lava within Upper Cretaceous sediments of heterogeneous petrographic composition. The mineral composition and the numerous textural variations are the results of different cooling histories. Intense spilitization was caused by descendent (sea water) and ascendent (juvenile) solutions. Products of the hydrothermal alteration are the result of very low to low-grade metamorphism. The contacts of the extrusives with surrounding sediments suggest an Upper Cretaceous age for the volcanism. The rocks resemble the extrusives found in other parts of Mt. Kalnik, as well as the extrusives from the wider area of NW Croatia and the rocks found in ophiolitic complexes of the Internal Dinarides.