Magma chamber dynamics recorded by oscillatory zoning in pyroxene and olivine phenocrysts in basaltic lunar meteorite Northwest Africa 032

2014 ◽  
Vol 99 (2-3) ◽  
pp. 355-368 ◽  
Author(s):  
S. M. Elardo ◽  
C. K. Shearer
Keyword(s):  
Magma Chamber ◽  
Oscillatory Zoning ◽  
Northwest Africa ◽  
Lunar Meteorite

scholarly journals New lunar meteorite Northwest Africa 2996: A window into farside lithologies and petrogenesis

2013 ◽  
Vol 48 (2) ◽  
pp. 289-315 ◽  
Author(s):  
Celestine N. Mercer ◽  
Allan H. Treiman ◽  
Katherine H. Joy
Keyword(s):  
Northwest Africa ◽  
Lunar Meteorite

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 Petrogenesis of lunar meteorite Northwest Africa 2977: Constraints from in situ microprobe results

2010 ◽  
Vol 45 (12) ◽  
pp. 1929-1947 ◽  
Author(s):  
Ai-Cheng ZHANG ◽  
Wei-Biao HSU ◽  
Christine FLOSS ◽  
Xian-Hua LI ◽  
Qiu-Li LI ◽  
...  
Keyword(s):  
Northwest Africa ◽  
Lunar Meteorite

Petrogenesis and chronology of lunar meteorite Northwest Africa 4472: A KREEPy regolith breccia from the Moon

2011 ◽  
Vol 75 (9) ◽  
pp. 2420-2452 ◽  
Author(s):  
K.H. Joy ◽  
R. Burgess ◽  
R. Hinton ◽  
V.A. Fernandes ◽  
I.A. Crawford ◽  
...  
Keyword(s):  
The Moon ◽  
Northwest Africa ◽  
Lunar Meteorite

Petrography and chronology of lunar meteorite Northwest Africa 6950

2020 ◽  
Vol 63 (4) ◽  
Author(s):  
Zemin Bao ◽  
Yuruo Shi ◽  
J. Lawford Anderson ◽  
Allen Kennedy ◽  
Zuokai Ke ◽  
...  
Keyword(s):  
Northwest Africa ◽  
Lunar Meteorite

The Youngest Toba Tuff (74 ka) Crystals Characterization

2020 ◽  
Author(s):  
Gabriela Nogo Retnaningtyas Bunga Naen ◽  
Atsushi Toramaru ◽  
Tomoharu Miyamoto ◽  
Haryo Edi Wibowo
Keyword(s):  
Magma Chamber ◽  
Fractional Crystallization ◽  
Optical Microscope ◽  
Oscillatory Zoning ◽  
Geochemical Data ◽  
Thin Sections ◽  
Decompression Rate ◽  
Wide Range ◽  
Different Characteristics ◽  
Toba Caldera

<p>Toba Caldera Complex, Indonesia is well known as the largest Quaternary caldera (87x33 km) that formed by four major eruptions among which the biggest one is the eruption of the Youngest Toba Tuff (YTT) about 74,000 years ago. Textural study of the pumice clast from YTT has been done to estimate the decompression rate by using bubble number density data. The result shows that decompression rate of Toba Caldera forming eruption varies in two order magnitude ranging from 10<sup>6 </sup>– 10<sup>8</sup> Pa/s. Southern pumices show the lower value than pumices from northern caldera. Similarly, new data about lithic distributions and mineral components of YTT from the northern and southern caldera showed several different characteristics. This fact suggests possibility of different processes which is distinguish production of southern and northern deposits. Therefore, understanding both conduit and chamber processes is needed to reveal the origin of differences in deposits. This study aims to elucidate magma chamber condition by characterizing the deposit especially crystals from YTT eruption.</p><p>Characterizations of Toba Tuffs have been made but not been enough to discuss YTT in detail. In this study, we focus on spatial differences in YTT deposits. Samples from four different locations were employed for the analyses. Component analysis was carried out on components larger than 2 mm. Whole-rock geochemical data were obtained by XRF. Petrography analysis for 37 thin sections was conducted using optical microscope. Textural analysis was carried out for 84 free crystals and 25 selected thin sections using microphotographs taken by SEM and further analyzed using image processing software. Chemical analysis for free crystal was carried out by SEM-EDS, while for pumices grain of 22 thin sections was conducted using EPMA.</p><p>Geochemical data showed that YTT magma is rhyodacitic to rhyolitic in whole-rock compositions with wide range of SiO<sub>2</sub> (69.15–76.83 wt.%). There are differences in abundance and type of pumices, free crystals, and lithic in each location<strong>.</strong> Major minerals are plagioclase, biotite, sanidine, and quartz. Common characteristics of northern and southern part deposit is that most of crystals are fractured, some forming aggregates, has anhedral shape and wide variation in size (0.003 mm<sup>2</sup>-13.113 mm<sup>2</sup>). However, there are differences between northern and southern deposits: presence of amphibole with larger size, orange quartz, sieve texture, patchy zoning, oscillatory zoning, crystal clots, and wider range of anorthite (An<sub>25</sub>– An<sub>87</sub>) is mostly found in northern deposits.</p><p>Plagioclase composition from northern part shows bimodal distribution suggesting that crystallization does not occur simultaneously by single process. Furthermore, plots of anorthite number versus size and of average anorthite number versus crystal content show random distribution, suggesting the complex crystallization of plagioclase: other processes than fractional crystallization in magma chamber. Moreover, presence of antecryst and disequilibrium textures in northern deposit indicates intervention from older rocks or even other systems. Different characteristics between northern and southern deposits suggest that YTT deposits are generated by multiple eruptions from independent, at least two magma chambers.</p><p>Keywords: Toba Caldera, the Youngest Toba Tuff (YTT), Crystal Characterization, Conduit Process, Chamber Process, Fractional Crystallization, Multiple eruptions</p>

Raman and infrared spectroscopic perspectives of lunar meteorite Northwest Africa 4884

2019 ◽  
Vol 51 (9) ◽  
pp. 1652-1666
Author(s):  
Haijun Cao ◽  
Jian Chen ◽  
Xiaohui Fu ◽  
Zongcheng Ling
Keyword(s):  
Northwest Africa ◽  
Lunar Meteorite ◽  
Infrared Spectroscopic

scholarly journals SEM-based Quantitative Analysis of Lunar Meteorite Northwest Africa 2727

2019 ◽  
Vol 25 (S2) ◽  
pp. 2492-2493
Author(s):  
Stephen M. Seddio ◽  
Sarah N. Valencia
Keyword(s):  
Quantitative Analysis ◽  
Northwest Africa ◽  
Lunar Meteorite

scholarly journals Geochemistry and mineralogy of a feldspathic lunar meteorite (regolith breccia), Northwest Africa 2200

Polar Science ◽  
2013 ◽  
Vol 7 (3-4) ◽  
pp. 241-259 ◽  
Author(s):  
Hiroshi Nagaoka ◽  
Yuzuru Karouji ◽  
Tomoko Arai ◽  
Mitsuru Ebihara ◽  
Nobuyuki Hasebe
Keyword(s):  
Northwest Africa ◽  
Lunar Meteorite
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