Mineral chemistry and geothermobarometry of the Balıkesir Volcanites (NW Anatolia, Turkey) 

2021 ◽  
Author(s):  
Alp Ünal ◽  
Şafak Altunkaynak
Keyword(s):  
Mineral Composition ◽  
Magma Chamber ◽  
Magma Mixing ◽  
Textural Properties ◽  
Mineral Chemistry ◽  
Oscillatory Zoning ◽  
Magma Chamber Processes ◽  
Crystallization Conditions ◽  
Compositional Variations ◽  
Opaque Minerals

<p>Balıkesir Volcanites (BV) are included into the Balıkesir Volcanic Province and contain various products of Oligo-Miocene volcanic activity in NW Anatolia. BV are formed from trachyandesite, andesite and dacite lavas with associated pyroclastic rocks. In this study, we report the petrographical investigations, mineral chemistry results and geothermobarometry calculations of the Balıkesir Volcanites in order to deduce the magma chamber processes and crystallization conditions. Andesites present a mineral composition of plagioclase (An35–50) + amphibole (edenitic hornblende) +biotite ± quartz and opaque minerals. The major phenocryst phases in dacite lavas are plagioclase (An39–53), quartz, amphibole (magnesio-hornblende), biotite, sanidine and opaque minerals. The mineral composition of the trachyandesites, on the other hand, is represented by plagioclase (An38–57) + amphibole (pargasitic hornblende) + biotite + clinopyroxene (endiopside- augite) ± sanidine ± quartz ± opaque minerals. Balıkesir Volcanites present distinct textural properties such as rounded plagioclase phenocrysts with reaction rims, oscillatory zoning, honeycomb and sieve textures in plagioclase, reverse mantled biotite and hornblende crystals. The plagioclase- amphibole geothermobarometry calculations of Balıkesir volcanites indicate that, andesite and dacite lavas present similar crystallization temperature and pressures conditions of 798- 813°C and 1,98- 2.17 kbar. Oppositely, trachyandesites were crystallized under 857°C and 3,72 kbar temperature and pressure conditions. These results show that the andesite and dacite lavas were originated from the same magma chamber with the depth of 7km whereas trachyandesites were evolved in a deeper magma chamber with 13 km depth. Combined mineral chemistry, petrography and geothermobarometry studies indicate that the open system processes such as magma mixing/mingling and/or assimilation fractional crystallization (AFC) were responsible for the textural and compositional variations of the Balıkesir Volcanites.</p>

scholarly journals Editorial for the Special Issue “Mineral Textural and Compositional Variations as a Tool for Understanding Magmatic Processes”

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 102
Author(s):  
Silvio Mollo ◽  
Flavio Di Stefano ◽  
Francesca Forni
Keyword(s):  
Magma Chamber ◽  
Igneous Rocks ◽  
Eruption Dynamics ◽  
Special Issue ◽  
Magma Chamber Processes ◽  
Magmatic Processes ◽  
Compositional Variations

This Special Issue of Minerals collects seven different scientific contributions highlighting how magma chamber processes and eruption dynamics studied either in the laboratory or in nature may ultimately control the evolutionary histories and geochemical complexities of igneous rocks [...]

Primitive intratransform volcanism at Garrett Transform Fault (East Pacific Rise)

1997 ◽  
Vol 34 (8) ◽  
pp. 1101-1117 ◽  
Author(s):  
R. Hébert ◽  
R. Hekinian ◽  
D. Bideau
Keyword(s):  
Magma Mixing ◽  
East Pacific Rise ◽  
Source Region ◽  
Mineral Chemistry ◽  
Oscillatory Zoning ◽  
Chromian Spinel ◽  
Transform Fault ◽  
East Pacific ◽  
Simply Connected ◽  
Ocean Ridge

The paper presents the results of a petrological study of samples collected by submersible from volcanic features that floor the intratransform domain of the Garrett Transform Fault. Most intratransform volcanics are typically highly porphyritic and primitive mid-ocean ridge basalt (MORB) (glasses have Mg# higher than 0.65), whereas most volcanics close to the East Pacific Rise – transform intersection zone are nearly aphyric evolved MORB (glasses have Mg# lower than 0.54). In the intratransform volcanics, phenocrysts and megacrysts are plagioclase and olivine and accessory spinel microphenocrysts in the magnesian lavas, and clinopyroxene and plagioclase in ferrobasalts. Variable mineral chemistry of plagioclase and spinel, chemical disequilibria between these phases and surrounding glass, and resorption features and oscillatory zoning in plagioclase suggest that limited magma mixing occurred during genesis of intratransform MORB. Aluminous- to chromian-spinel compositions are in agreement with melt interactions in small magma pockets. These processes are superimposed on complex partial melting events of a heterogeneous source region underlying the intratransform domain. Generation of most ferrobasalts can be explained by crystal fractionation of primitive MORB. Some ferrobasalts appear to derive from discrete magma bodies, since they are not simply connected to the magnesian tholeiites through fractional crystallization processes.

scholarly journals Igneous Rock Associations 23. The Bushveld Complex, South Africa: New Insights and Paradigms

2019 ◽  
Vol 45 (3-4) ◽  
pp. 117-135
Author(s):  
Stephen A. Prevec
Keyword(s):  
Magma Chamber ◽  
Bushveld Complex ◽  
Magma Mixing ◽  
Layered Intrusion ◽  
Ore Deposits ◽  
Magmatic Fluid ◽  
Magma Chamber Processes ◽  
Ore Minerals ◽  
Gravity Driven ◽  
Conventional Cooling

SUMMARYThe Bushveld Complex has continued to serve as the basis for study into the fundamental nature of petrological processes for layered intrusion formation and for oxide and sulphide hosted Platinum Group Element (PGE)–Cu–Ni ore deposits. These studies have included discoveries in terms of the physical extent of Bushveld magmatism, both laterally and internally. Lateral variations in the mafic to ultramafic Rustenburg Layered Suite of the Northern Lobe of the complex have also revealed petrologically distinctive Upper Critical Zone equivalent rocks (the so-called Flatreef) with enhanced contamination and mineralization traits that reflect a transition between Eastern and Western Lobe equivalent stratigraphy and Platreef-style complexity. Traditional magma mixing models have been re-examined in light of radiogenic isotopic evidence for crustal involvement early in the chromite precipitation or formation process, combined with evidence for associated heterogeneous fluid contents, cryptic layering profiles, and textural evidence. A wide variety of alternative ore-genesis models have been proposed as a consequence. The fundamental mechanics of magma chamber processes and the existence of the magma chamber as an entity have been called into question through various lines of evidence which have promoted the concept of progressive emplacement of the complex as a stack of not-necessarily-quite-sequentially intruded sills (with or without significant quantities of transported phenocrysts), emplaced into variably crystallized and compacted crystal-liquid mush mixtures, modified by compaction-driven late magmatic fluid (silicate and aqueous) activity. Alternatively, petrological and geochemical observations have been used to discount these interpretations in favour of more conventional cooling and gravity-driven accumulation of silicate and ore minerals in a large, liquid-dominated system.RÉSUMÉLe complexe de Bushveld a demeuré à la base d’études sur la nature fondamentale des processus pétrologiques de formation d’intrusions litées et des gîtes des éléments du groupe platine (ÉGP)-Cu-Ni hébergés dans les oxydes et les sulfures. Ces études ont comporté des découvertes sur l’étendue physique, à la fois latérale et interne, du magmatisme de Bushveld. Les variations latérales de la suite stratifiée et mafique à ultramafique Rustenburg du lobe nord du complexe ont également révélé des roches équivalentes pétrologiquement distinctes de la zone critique supérieure (le communément désigné Flatreef) avec des traits de contamination et de minéralisation accrus qui reflètent une transition entre la stratigraphie équivalente des lobes est et ouest et la complexité de type Platreef. Les modèles traditionnels de mélanges magmatiques ont été réexaminés à la lumière de preuves isotopiques radiogéniques indiquant une implication de la croûte au début du processus de précipitation ou de formation de la chromite, combinées à des preuves de contenu fluide hétérogène associé, de profils de litage cryptique et de preuves texturales. Ainsi, une grande variété de modèles alternatifs de genèse de minerai a été proposée. La mécanique fondamentale des processus de la chambre magmatique et l'existence de la chambre magmatique en tant qu'entité ont été remises en question au moyen de divers éléments de preuve qui ont mis en avant le concept de mise en place progressive du complexe sous forme d'un empilement non-nécessairement séquentiel de sills injectés (avec ou sans quantités significatives de phénocristaux transportés) mis en place dans des mélanges de bouillie cristaux/liquide à cristallisation et compaction variable, modifiés par une activité tardive de fluide magmatique (silicaté et aqueux) induite par la compaction. Alternativement, des observations pétrologiques et géochimiques ont été utilisées pour écarter ces interprétations en faveur d'un processus plus conventionnel de refroidissement et d’accumulation de minérais silicatés et minéralisés induite par la gravité dans un vaste système à dominance liquide.

Mineral chemistry of the Mull-Morvern Tertiary lava succession, western Scotland

1998 ◽  
Vol 62 (3) ◽  
pp. 295-312 ◽  
Author(s):  
Andrew C. Kerr
Keyword(s):  
Trace Element ◽  
Magma Chamber ◽  
Magma Mixing ◽  
Mineral Chemistry ◽  
Fractional Crystallisation ◽  
Basic Material ◽  
Mixing Processes ◽  
Trace Element Chemistry ◽  
Wide Range ◽  
Mineral Compositions

AbstractThe 1800 m thick preserved remnant of the Tertiary lava succession of Mull and Morvern consists of three basic mantle-derived magma types, with compositions varying from tholeiitic to mildly alkalic, and from picritic basalts to trachytes. This results in a similarly wide range in mineral compositions. Contrary to the suggestions of previous workers the mineral chemistry of the lava succession (in conjunction with published major and trace element chemistry) is strongly supportive of a fractional crystallisation origin for the more evolved lavas.Resorped and regrown (with more basic material) plagioclase phenocrysts found in the more-evolved are indicative of magma mixing processes involving replenishment of an evolving magma chamber with more-basic magma. Lavas containing 15–20 vol.% plagioclase phenocrysts probably represent eruptions from the top of a magma chamber where flotation cumulates of plagioclase had developed. Fragmental phenocrysts found in some highly plagioclase phyric lavas (from near the top of the preserved lava succession) suggest that the eruption of lavas may have been explosive.

PETROCHEMISTRY AND MAGMA CHAMBER PROCESSES OF THE PERUVIAN COASTAL BATHOLITH GRANITES IN THE NORTHERN PART OF THE AREQUIPA SEGMENT

2016 ◽  
Author(s):  
Ana Maria Martinez ◽  
◽  
Benjamin L. Clausen ◽  
Scott R. Paterson ◽  
Vali Memeti
Keyword(s):  
Magma Chamber ◽  
Magma Chamber Processes
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