scholarly journals Isotopic and Trace Element Remote Sensing of Montana Continental Lithosphere from Erupted Magmas

2019 ◽  
Keyword(s):  
Remote Sensing ◽  
Trace Element ◽  
Continental Lithosphere

scholarly journals Micro-Analytical Studies of the Petrogenesis of  Silicic Arc Magmas in the Taupo Volcanic Zone  and Southern Kermadec Arc, New Zealand

2021 ◽  
Author(s):  
◽  
Katharine Emma Saunders
Keyword(s):  
Trace Element ◽  
Melt Inclusions ◽  
Fractional Crystallisation ◽  
Taupo Volcanic Zone ◽  
Continental Lithosphere ◽  
Crystal Mush ◽  
Volcanic Zone ◽  
Element Modelling ◽  
Magma Genesis ◽  
Arc Magmas

<p>The petrogenesis of silicic arc magmas is controversial with end-member models of fractional crystallisation and crustal anatexis having been invoked. A prime example of this is the archetypical continental Taupo Volcanic Zone and the adjacent oceanic Kermadec Arc. Insights into the genesis and timescales of magmatic processes of four continental rhyolitic magmas (Whakamaru, Oruanui, Taupo and Rotorua eruptives) and an oceanic (Healy seamount) rhyodacitic magma are documented through micro-analytical chemical studies of melt inclusions and crystal zonation of plagioclase and quartz. Electron probe microanalysis, laser ablation inductively coupled plasma mass spectrometry and Fourier transform infrared spectroscopy have been used to measure major, trace and volatile element concentrations, respectively, of melt inclusions and crystals. Melt inclusions are high silica (e.g. 74 - 79 wt%) irrespective of arc setting and display a wide range of trace element compositions (e.g. Sr = 17 - 180 ppm). Taupo Volcanic Zone melt inclusions exhibit higher K2O and Ce/Yb relative to Healy melt inclusions reflecting the assimilation of continental lithosphere. Quantitative trace element modelling of melt inclusion compositions: (a) demonstrates that magma genesis occurred through 62 - 76% fractional crystallisation at Healy whereas assimilation of continental lithosphere (greywacke) in addition to 60 - 80% fractional crystallisation is required for the Taupo Volcanic Zone magmas; and (b) suggests the presence of crystal mush bodies beneath silicic magma chambers in both continental and oceanic arc environments. Water concentrations of melt inclusions ranged between 1.4 - 5.1 wt% for the Whakamaru, Taupo and Healy samples. However, the inconsistency in the measured molecular water to hydroxyl concentrations of melt inclusions relative to those determined experimentally for groundmass rhyolitic glasses provide evidence for the degassing of inclusions prior to quenching, by diffusion of hydroxyl groups through the crystal host. Thus, partial pressures of water estimated from the inclusions and inferred depths of the crystallising magma bodies are underestimated. Chemical profiles of mineral zonation, however, indicate a more complex origin of silicic melts than simple fractionation and assimilation. For example, trace element modelling of Whakamaru plagioclase suggests that the three distinct textural plagioclase populations present in Whakamaru samples crystallised from four physiochemically discrete silicic melts. This modelling indicates a strong petrogenetic link between andesitic and silicic magmas from the chemical variation of selected Whakamaru plagioclase crystals possessing high anorthite (45-60 mol %) cores and low anorthite (~ 30 mol %) rim compositions and the interaction of greywacke partial melts. Furthermore, Sr diffusion modelling of core-rim interfaces of the same plagioclase crystals indicate the amalgamation of the magma chamber occurred continuously over the 15,000 years preceding the climactic eruption. Conversely, the major element zonation of Taupo plagioclases implies magma genesis occurred solely through assimilation and fractional crystallisation without the incorporation of evolved crystal mush magmas, indicating a spectrum of magmatic processes are occurring beneath the Taupo Volcanic Zone with each eruption providing only a snapshot of the petrogenesis of the Taupo Volcanic Zone.</p>

scholarly journals Evidence for a Carbonatite-Influenced Source Assemblage for Intraplate Basalts from the Buckland Volcanic Province, Queensland, Australia

Minerals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 546 ◽  
Author(s):  
Joshua J. Shea ◽  
Stephen F. Foley
Keyword(s):  
Trace Element ◽  
Mantle Source ◽  
Alkali Basalt ◽  
Element Concentration ◽  
Continental Lithosphere ◽  
Alkali Basalts ◽  
Volcanic Province ◽  
Eastern Australia ◽  
Low K ◽  
Similar Enrichment

Eastern Australia contains a widespread suite of primitive (MgO ≥ 7.5 wt.%) intraplate basaltic provinces, including those sited along the longest continental hotspot track on Earth (≈2000 km), the Cosgrove track. The Buckland volcanic province is the most southerly basaltic province on the Cosgrove track before a >1600 km stretch that contains only sparse leucitite volcanism. Buckland is also situated just northeast of the edge of thick cratonic lithosphere where it transitions to a thinner continental lithosphere (<110 km) to the east, which may influence the production of plume-derived melts. Here, analysis of minor and trace elements in olivines in alkali basalts and basanites from the Buckland Province are combined with whole-rock compositions to elucidate the mantle source assemblages, and to calibrate minor and trace element indicators in olivine for application to source mineralogy. Olivine xenocrysts show element concentration ranges typical for peridotites; Mn and Al concentrations indicate that the ambient mantle is spinel, rather than garnet, peridotite. High modal pyroxene content is indicated by high Ni, Zn/Fe, and Fe/Mn in olivines, while high Ti/Sc is consistent with amphibole in the source. Residual phlogopite in the source of the basanites is indicated by low K/Nb in whole rocks, while apatite contains high P2O5 and low Rb/Sr (≥0.015) and Sr/La (≥13). The basanite source assemblage probably contains apatite, phlogopite, olivine, clinopyroxene and orthopyroxene, whereas the alkali basalt source assemblage is probably amphibole, olivine, orthopyroxene and clinopyroxene ± phlogopite ± apatite. Both source assemblages correspond broadly to olivine websterite, with the basanite source lying deeper than that for alkali basalt, explaining the occurrence of phlogopite in the source. This mineralogy, along with whole-rock Ti/Eu, Zr/Hf and P2O5/TiO2 values approaching those of natural carbonatites, provide evidence showing that the Buckland source consists of a peridotite that has interacted with a carbonate-rich melt whose origin may be in the deep lithosphere or asthenosphere beneath the craton. Similar enrichment processes are probably common throughout eastern Australia, controlling trace element characteristics in basaltic provinces. The topography of the underside of the lithosphere may play a significant role in determining mantle source assemblages by diverting and concentrating melt flow, and thus influence the location of basaltic provinces.

scholarly journals A new tool to probe lithosphere evolution: OH signatures of pyroxenes

2021 ◽  
Author(s):  
Jannick Ingrin
Keyword(s):  
Trace Element ◽  
Infrared Spectra ◽  
Critical Review ◽  
Oceanic Lithosphere ◽  
Exact Nature ◽  
Schematic Diagram ◽  
Continental Lithosphere ◽  
Review Of The Literature ◽  
Frequency Range

&lt;p&gt;Four OH stretching bands in the frequency range 3300 &amp;#8211; 3700 cm&lt;sup&gt;-1&lt;/sup&gt; dominate the infrared spectra of lithospheric pyroxenes. Depending on their metasomatic history or geodynamic origin, they have characteristic OH signatures. Pyroxenes from continental lithosphere that undergone &amp;#8220;wet&amp;#8221; metasomatism have distinct signature of those having undergone &amp;#8220;dry&amp;#8221; metasomatism. Pyroxenes from oceanic lithosphere have yet a third type of signature. Our most recent analyses of xenoliths and a critical review of the literature show that the phenomenon is widely distributed among continents and oceans. The phenomenon affects simultaneously opx and cpx from the same rock and various lithologies: peridotites, pyroxenites and granulites. In continental lithosphere, pyroxenes affected by &amp;#8220;wet&amp;#8221; metasomatism are dominated by OH bands at 3600 and 3415 cm&lt;sup&gt;-1&lt;/sup&gt; for opx and 3635 and 3445 cm&lt;sup&gt;-1&lt;/sup&gt; for cpx . Whereas pyroxenes affected by &amp;#8220;dry&amp;#8221; metasomatism are dominated by OH bands at 3570 and 3515 cm&lt;sup&gt;-1&lt;/sup&gt; for opx and 3595 and 3515 cm&lt;sup&gt;-1&lt;/sup&gt; for cpx. Opxs from oceanic lithosphere have OH spectra dominated by the band at 3415 cm&lt;sup&gt;-1&lt;/sup&gt;, and with a smaller by bands at 3520 and 3570 cm&lt;sup&gt;-1&lt;/sup&gt; (Fig. 1).&lt;/p&gt;&lt;p&gt;In all these observations it was not possible to correlate the signatures with a specific major, minor or trace element. Therefore, the exact nature of the observed signatures remains unidentified. Notwithstanding, these OH signatures are representative of specific lithospheric events and offer a potential new benchmark for the study of lithospheric processes.&lt;/p&gt;&lt;p&gt;Fig.1&amp;#160;: Schematic diagram showing the 3 types of signatures for opx. Spectra from opxs in oceanic lithosphere are from Gose, J., Schmadicke, E. and Beran A.: Geology, 37, 543-546, 2009. Drawing of subduction is from WangZ-Z., Liu,J., Xia, Q-K., Hao Y_T. and Wang Q-Y.: Lithos, 360-361, 2020.&lt;/p&gt;&lt;p&gt;&lt;img src=&quot;https://contentmanager.copernicus.org/fileStorageProxy.php?f=gepj.124142acd70060797211161/sdaolpUECMynit/12UGE&amp;app=m&amp;a=0&amp;c=e5a56ce0ae9e538db3dd556392f1dd4d&amp;ct=x&amp;pn=gepj.elif&amp;d=1&quot; alt=&quot;&quot;&gt;&lt;/p&gt;

Geo-environmental evaluation of Wadi El Raiyan Lakes, Egypt, using remote sensing and trace element techniques

2017 ◽  
Vol 10 (10) ◽  
Author(s):  
Hend S. Abu Salem ◽  
Atef Abu Khatita ◽  
Mamdouh M. Abdeen ◽  
Essam A. Mohamed ◽  
Ahmed M. El Kammar
Keyword(s):  
Remote Sensing ◽  
Trace Element ◽  
Environmental Evaluation

scholarly journals Micro-Analytical Studies of the Petrogenesis of  Silicic Arc Magmas in the Taupo Volcanic Zone  and Southern Kermadec Arc, New Zealand

2021 ◽  
Author(s):  
◽  
Katharine Emma Saunders
Keyword(s):  
Trace Element ◽  
Melt Inclusions ◽  
Fractional Crystallisation ◽  
Taupo Volcanic Zone ◽  
Continental Lithosphere ◽  
Crystal Mush ◽  
Volcanic Zone ◽  
Element Modelling ◽  
Magma Genesis ◽  
Arc Magmas

<p>The petrogenesis of silicic arc magmas is controversial with end-member models of fractional crystallisation and crustal anatexis having been invoked. A prime example of this is the archetypical continental Taupo Volcanic Zone and the adjacent oceanic Kermadec Arc. Insights into the genesis and timescales of magmatic processes of four continental rhyolitic magmas (Whakamaru, Oruanui, Taupo and Rotorua eruptives) and an oceanic (Healy seamount) rhyodacitic magma are documented through micro-analytical chemical studies of melt inclusions and crystal zonation of plagioclase and quartz. Electron probe microanalysis, laser ablation inductively coupled plasma mass spectrometry and Fourier transform infrared spectroscopy have been used to measure major, trace and volatile element concentrations, respectively, of melt inclusions and crystals. Melt inclusions are high silica (e.g. 74 - 79 wt%) irrespective of arc setting and display a wide range of trace element compositions (e.g. Sr = 17 - 180 ppm). Taupo Volcanic Zone melt inclusions exhibit higher K2O and Ce/Yb relative to Healy melt inclusions reflecting the assimilation of continental lithosphere. Quantitative trace element modelling of melt inclusion compositions: (a) demonstrates that magma genesis occurred through 62 - 76% fractional crystallisation at Healy whereas assimilation of continental lithosphere (greywacke) in addition to 60 - 80% fractional crystallisation is required for the Taupo Volcanic Zone magmas; and (b) suggests the presence of crystal mush bodies beneath silicic magma chambers in both continental and oceanic arc environments. Water concentrations of melt inclusions ranged between 1.4 - 5.1 wt% for the Whakamaru, Taupo and Healy samples. However, the inconsistency in the measured molecular water to hydroxyl concentrations of melt inclusions relative to those determined experimentally for groundmass rhyolitic glasses provide evidence for the degassing of inclusions prior to quenching, by diffusion of hydroxyl groups through the crystal host. Thus, partial pressures of water estimated from the inclusions and inferred depths of the crystallising magma bodies are underestimated. Chemical profiles of mineral zonation, however, indicate a more complex origin of silicic melts than simple fractionation and assimilation. For example, trace element modelling of Whakamaru plagioclase suggests that the three distinct textural plagioclase populations present in Whakamaru samples crystallised from four physiochemically discrete silicic melts. This modelling indicates a strong petrogenetic link between andesitic and silicic magmas from the chemical variation of selected Whakamaru plagioclase crystals possessing high anorthite (45-60 mol %) cores and low anorthite (~ 30 mol %) rim compositions and the interaction of greywacke partial melts. Furthermore, Sr diffusion modelling of core-rim interfaces of the same plagioclase crystals indicate the amalgamation of the magma chamber occurred continuously over the 15,000 years preceding the climactic eruption. Conversely, the major element zonation of Taupo plagioclases implies magma genesis occurred solely through assimilation and fractional crystallisation without the incorporation of evolved crystal mush magmas, indicating a spectrum of magmatic processes are occurring beneath the Taupo Volcanic Zone with each eruption providing only a snapshot of the petrogenesis of the Taupo Volcanic Zone.</p>

Phased Arrays for Radio Astronomy, Remote Sensing, and Satellite Communications

2018 ◽  
Author(s):  
Karl F. Warnick ◽  
Rob Maaskant ◽  
Marianna V. Ivashina ◽  
David B. Davidson ◽  
Brian D. Jeffs
Keyword(s):  
Remote Sensing ◽  
Radio Astronomy ◽  
Phased Arrays ◽  
Satellite Communications
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