Mineral chemistry and geothermometry of Fe-Ti oxides in the Khanlogh magnetite-apatite ore, northwest of Neyshabour, NE Iran

2016 ◽  
Vol 281 (3) ◽  
pp. 227-246
Author(s):  
Parvin Najafzadeh Tehrani ◽  
Ali Asghar Calagari ◽  
Francisco Velasco Roldan ◽  
Vartan Simmonds ◽  
Kamal Siahcheshm
Keyword(s):  
Mineral Chemistry ◽  
Ti Oxides ◽  
Ne Iran

Mineral chemistry and P-T conditions of the adakitic rocks from Torud–Ahmad Abad magmatic belt, S-SE Shahrood, NE Iran

2017 ◽  
Vol 182 ◽  
pp. 110-120
Author(s):  
Fazilat Yousefi ◽  
Mahmoud Sadeghian ◽  
Christina Wanhainen ◽  
Habibollah Ghasemi ◽  
Papadopoulou Lambrini ◽  
...  
Keyword(s):  
Mineral Chemistry ◽  
Adakitic Rocks ◽  
Ne Iran

scholarly journals MAGMA GENERATION AND MIXING IN THE EARLIEST VOLCANIC CENTRE OF SANTORINI (AKROTIRI PENINSULA). MINERAL CHEMISTRY EVIDENCE FROM THE AKROTIRI PYROCLASTICS

2017 ◽  
Vol 43 (5) ◽  
pp. 2625
Author(s):  
K. Kitsopoulos
Keyword(s):  
Magma Mixing ◽  
Mineral Chemistry ◽  
Silicic Magma ◽  
High Alumina ◽  
Primitive Mantle ◽  
Volcanic Centre ◽  
Magma Generation ◽  
High Alumina Basalt ◽  
Ti Oxides

Santorini is a dominant expression of magma generation and subsequent volcanism in the Meditereanean area, where a calk-alkaline, high-alumina, basalt-andesite-dacite type of volcanism was expressed from eight centres. The volcanics of the Akrotiri peninsula are considered to be the products of the earliest (Pliocene Pleistocene) volcanic centre. The present study has investigated the mineral chemistry of some major pyrogenic phenocrysts, such as plagioclase and Fe-Ti oxides, of the Akrotiri pyroclatics unit, which have undergone a notable zeolitization procedure. The results are compatible with magma mixing mechanism of a primitive mantle derived, saturated, of mafic composition component with silicic magma in shallow crustal depths.

Petrology of sub-cratonic pyroxenite and eclogite containing lamellae-bearing garnet, Western Gneiss Region, Norway

2020 ◽  
Author(s):  
Dirk Spengler ◽  
Taisia A. Alifirova ◽  
Herman L. M. van Roermund ◽  
Hans-Joachim Massonne
Keyword(s):  
Lithospheric Mantle ◽  
Mineral Chemistry ◽  
Wide Distribution ◽  
Stability Field ◽  
Western Gneiss Region ◽  
Entire Area ◽  
Ultra High Pressure ◽  
Ti Oxides ◽  
Lamellar Inclusions ◽  
Micron Size

<p>Garnet from the lithospheric mantle underneath cratons can contain oriented lamellar inclusions of pyroxene and oxides like rutile as a result of exsolution of majoritic and titaniferous components due to cooling and/or decreasing pressure. We investigated ten new such microstructure-bearing samples of pyroxenite and eclogite from six peridotite bodies in SW Norway, which were once located in the E Greenland mantle lithosphere. The lamellar inclusions occur in porphyroclastic garnet and vary – dependent on their size – systematically in shape, (acicular to short-prismatic), width (~50 μm to sub-micron size), spacing (several 100 to ~10 μm), and phase (pyroxene to pyroxene + Ti-oxides to Ti-oxides). Smaller lamellae can fill the space between larger lamellae, which support consecutive generations. The larger (early formed) lamellae are more poorly preserved and more difficult to locate in the suite of samples than the smaller (lately formed) exsolutes. A younger generation of lamellar and other inclusions occur lined-up along healed cracks cutting across cores but not rims of garnet. These inclusions comprise oxides, silicates, carbonates (aragonite, calcite, magnesite) and fluid inclusions (N<sub>2</sub>, CO<sub>2</sub>, H<sub>2</sub>O). Their origin either relates to the Precambrian rock history and/or to a hydrous environment as typical for mantle wedge metasomatism prior to Scandian recrystallisation. Mineral chemistry suggests that the lamellae-bearing garnet grains equilibrated at two discrete depth levels, corresponding to ~3.7 GPa (850 °C) and ~3.0 GPa (710 °C), at a cratonic geotherm corresponding to 38 mW/m<sup>2</sup> surface heat flow. Five samples contain porphyroclastic orthopyroxenes with Al<sub>2</sub>O<sub>3</sub> concentration showing W-shaped profiles and/or very low Al<sub>2</sub>O<sub>3</sub> content (0.18–0.23 wt%) in cores of large (>200 µm) recrystallised grains. Both characteristics typify short intracrystalline diffusion lengths and are consistent with an early prograde metamorphic evolution into the diamond stability field. This evolution is related to subduction during the Scandian orogeny. Porphyroclastic orthopyroxenes in other samples show U-shaped Al<sub>2</sub>O<sub>3</sub> concentration profiles and long diffusion lengths of several 100 μm, i.e. longer than the grain radius of the recrystallised grains. Their cores contain high Al<sub>2</sub>O<sub>3</sub> contents (0.65–1.16 wt%) consistent with a diffusional overprint that followed partial rock recrystallisation and obliterated pro- and peak metamorphic records. The presence of systematic exsolution microstructures in all samples demonstrates a similar early evolution of pyroxenite and eclogite in all six peridotite bodies. The wide distribution of our samples across the Western Gneiss Region indicates that (1) majoritic and titaniferous garnet occurred widespread in the E Greenland lithospheric mantle and (2) rock bodies of Scandian ultra-high pressure metamorphism can be found in nearly the entire area between Nordfjord and Storfjord and from the coast towards ~100 km in the hinterland, i.e. in a region much larger than previously anticipated.</p>

Mineral chemistry and Ti in zircon thermometry: Insights into magmatic evolution of the Sangan igneous rocks, NE Iran

Geochemistry ◽  
2018 ◽  
Vol 78 (2) ◽  
pp. 205-214 ◽  
Author(s):  
Fatemeh Sepidbar ◽  
Hassan Mirnejad ◽  
Changqian Ma
Keyword(s):  
Mineral Chemistry ◽  
Igneous Rocks ◽  
Magmatic Evolution ◽  
Zircon Thermometry ◽  
Ne Iran
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