Analysis of Experimentally Zoned Crystals to Investigate The Thermo-Chemical Evolution of Magma Reservoirs

2020 ◽  
Author(s):  
Alessandro Musu ◽  
Luca Caricchi ◽  
Diego Perugini ◽  
Rosa Anna Corsaro ◽  
Francesco Vetere ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Magma Mixing ◽  
Deformation Gradient ◽  
Major And Trace Elements ◽  
Machine Learning Algorithms ◽  
Concentric Cylinder ◽  
Distribution Maps ◽  
Chemical Zoning ◽  
Magma Reservoirs ◽  
Static Conditions

<p>Magma reservoirs are characterized by thermal and chemical gradients producing large variations of the spatial distribution of the physical properties of the magma they contain. Understanding the pre-eruptive thermal, chemical and physical evolution of magma represents an important step to correctly interpret the signs of an impending eruption. In this framework, the chemical zoning of minerals, which provide us a record of these thermal and chemical perturbations, represents an important tool to reconstruct reservoir dynamics. We study the effect of the competition between changing intensive parameters, element diffusion and mineral growth on the chemical zoning of minerals. We grow chemical zoned minerals at the Petro-Volcanology Research Group of the University of Perugia, using tephra from 2002-03 Mt. Etna eruption as starting material. The zonation in minerals is been forced inside a high-temperature furnace by oscillating the temperature under three different conditions: static conditions, using a controlled deformation gradient (concentric cylinder apparatus) and using a chaotic mixing regime (Chaotic Magma Mixing Device – CMMD). We collect major and trace elements distribution maps on a large number of crystals using Electron Probe Micro Analyzer (EPMA) and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS), respectively. The data will be analysed using a series of custom built machine learning algorithms to disentangle zoning related to variations of the thermodynamic conditions of crystal growth from the effects of the competition between diffusion and growth. Our data will help deciphering the zoning patterns observed in natural crystals, improve our understanding of magma reservoir dynamics and help the interpretation of monitoring signals in the period preceding a volcanic eruption.</p>

Crystal zoning patterns: competition between crystal growth and elements diffusion

2021 ◽  
Author(s):  
Alessandro Musu ◽  
Luca Caricchi ◽  
Diego Perugini ◽  
Rosa Anna Corsaro ◽  
Francesco Vetere ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Volcanic Activity ◽  
Magma Mixing ◽  
Deformation Gradient ◽  
Machine Learning Algorithms ◽  
Chemical Zoning ◽  
Magma Reservoirs ◽  
Physico Chemical ◽  
Thermodynamic Conditions ◽  
Static Conditions

<p>Magma reservoirs represent areas of large variation in the physico-chemical properties of magmas and are directly associated with volcanic activity. Understanding the processes acting at inaccessible depths is of crucial importance to interpret monitoring signals and to develop quantitative models to forecast volcanic activity. Minerals are witnesses of the temporal evolution of the physico-chemical conditions within magma reservoirs recording variations of intensive parameters as chemical signals. However, the competition between crystal growth and elements diffusion in the melt phase can also modulate the chemical zoning of minerals, therefore complicating the interpretation of chemical zoning patterns. To disentangle this complexity, chemically zoned minerals are synthetically grown at the Petro-Volcanology Research Group of the University of Perugia, under controlled conditions. For these experiments tephra from 2002-03 Mt. Etna eruption is used as starting material. The zonation in minerals is been forced inside a high-temperature furnace by oscillating the temperature with three different setups: static conditions, using a controlled deformation gradient (Concentric Cylinder Apparatus) and using a chaotic mixing regime (Chaotic Magma Mixing Device). The zoned crystals are analysed for major and trace elements by Electron Probe Micro Analyzer (EPMA) and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS), respectively. High spatial resolution elemental maps (0.5 micrometres) are also collected to characterise the zoning of selected crystals. The data are analysed using a series of custom-built machine learning algorithms to disentangle zoning related to variations of the thermodynamic conditions of crystal growth from the effects of the competition between diffusion and growth. The main target of this project is to provide quantitative tools to distinguish between chemical zoning forced by thermodynamic conditions of growth and chemical zoning produced by competition between crystal growth and element diffusion.</p>

scholarly journals Magma Mixing Genesis of the Mafic Enclaves in the Qingshanbao Complex of Longshou Mountain, China: Evidence from Petrology, Geochemistry, and Zircon Chronology

Minerals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 195 ◽  
Author(s):  
Wenheng Liu ◽  
Xiaodong Liu ◽  
Jiayong Pan ◽  
Kaixing Wang ◽  
Gang Wang ◽  
...  
Keyword(s):  
Host Rock ◽  
Inductively Coupled Plasma ◽  
Magma Mixing ◽  
Coarse Grained ◽  
Calc Alkaline ◽  
Quartz Crystals ◽  
Alkaline Rocks ◽  
Mafic Enclaves ◽  
Normal Zoning ◽  
Host Rocks

The Qingshanbao complex, part of the uranium metallogenic belt of the Longshou-Qilian mountains, is located in the center of the Longshou Mountain next to the Jiling complex that hosts a number of U deposits. However, little research has been conducted in this area. In order to investigate the origin and formation of mafic enclaves observed in the Qingshanbao body and the implications for magmatic-tectonic dynamics, we systematically studied the mineralogy, petrography, and geochemistry of these enclaves. Our results showed that the enclaves contain plagioclase enwrapped by early dark minerals. These enclaves also showed round quartz crystals and acicular apatite in association with the plagioclase. Electron probe analyses showed that the plagioclase in the host rocks (such as K-feldspar granite, adamellite, granodiorite, etc.) show normal zoning, while the plagioclase in the mafic enclaves has a discontinuous rim composition and shows instances of reverse zoning. Major elemental geochemistry revealed that the mafic enclaves belong to the calc-alkaline rocks that are rich in titanium, iron, aluminum, and depleted in silica, while the host rocks are calc-alkaline to alkaline rocks with enrichment in silica. On Harker diagrams, SiO2 contents are negatively correlated with all major oxides but K2O. Both the mafic enclaves and host rock are rich in large ion lithophile elements such as Rb and K, as well as elements such as La, Nd, and Sm, and relatively poor in high field strength elements such as Nb, Ta, P, Ti, and U. Element ratios of Nb/La, Rb/Sr, and Nb/Ta indicate that the mafic enclaves were formed by the mixing of mafic and felsic magma. In terms of rare earth elements, both the mafic enclaves and the host rock show right-inclined trends with similar weak to medium degrees of negative Eu anomaly and with no obvious Ce anomaly. Zircon LA-ICP-MS (Laser ablation inductively coupled plasma mass spectrometry) U-Pb concordant ages of the mafic enclaves and host rock were determined to be 431.8 5.2 Ma (MSWD (mean standard weighted deviation)= 1.5, n = 14) and 432.8 4.2 Ma (MSWD = 1.7, n = 16), respectively, consistent with that for the zircon U-Pb ages of the granite and medium-coarse grained K-feldspar granites of the Qingshanbao complex. The estimated ages coincide with the timing of the late Caledonian collision of the Alashan Block. This comprehensive analysis allowed us to conclude that the mafic enclaves in the Qingshanbao complex were formed by the mixing of crust-mantle magma with mantle-derived magma due to underplating, which caused partial melting of the ancient basement crust during the collisional orogenesis between the Alashan Block and Qilian rock mass in the early Silurian Period.

scholarly journals Extreme isotopic heterogeneity in Samoan clinopyroxenes constrains sediment recycling

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jenna V. Adams ◽  
Matthew G. Jackson ◽  
Frank J. Spera ◽  
Allison A. Price ◽  
Benjamin L. Byerly ◽  
...  
Keyword(s):  
Mantle Source ◽  
Magma Mixing ◽  
Major And Trace Elements ◽  
Mantle Heterogeneity ◽  
Isotopic Data ◽  
Nd Isotopes ◽  
Isotopic Heterogeneity ◽  
Total Variability ◽  
High Silica ◽  
Insight Into

AbstractLavas erupted at hotspot volcanoes provide evidence of mantle heterogeneity. Samoan Island lavas with high 87Sr/86Sr (>0.706) typify a mantle source incorporating ancient subducted sediments. To further characterize this source, we target a single high 87Sr/86Sr lava from Savai’i Island, Samoa for detailed analyses of 87Sr/86Sr and 143Nd/144Nd isotopes and major and trace elements on individual magmatic clinopyroxenes. We show the clinopyroxenes exhibit a remarkable range of 87Sr/86Sr—including the highest observed in an oceanic hotspot lava—encompassing ~30% of the oceanic mantle’s total variability. These new isotopic data, data from other Samoan lavas, and magma mixing calculations are consistent with clinopyroxene 87Sr/86Sr variability resulting from magma mixing between a high silica, high 87Sr/86Sr (up to 0.7316) magma, and a low silica, low 87Sr/86Sr magma. Results provide insight into the composition of magmas derived from a sediment-infiltrated mantle source and document the fate of sediment recycled into Earth’s mantle.

Rejuvenation events recorded in alkali feldspar from the Tuolumne Intrusive Complex

2021 ◽  
Author(s):  
Susanne Seitz ◽  
Guilherme Gualda ◽  
Luca Caricchi
Keyword(s):  
Trace Elements ◽  
Hierarchical Clustering ◽  
Alkali Feldspar ◽  
Growth Conditions ◽  
Major And Trace Elements ◽  
Sem Analysis ◽  
Intrusive Complex ◽  
Cluster Number ◽  
Chemical Zoning ◽  
Chemical Signatures

<p>Zoned minerals preserve information about their growth conditions, by changing their composition as function of temperature, pressure and melt composition. By carefully looking at a zoned minerals we can determine characteristics of the main stages of the evolution of magmatic systems.</p><p>We study alkali feldspar megacrysts from the Tuolumne Intrusive Complex in California, with the aim of deciphering chemical signatures of rejuvenation events. We characterize the chemical zoning of alkali feldspar using X-ray tomography, BSE imaging, EDS-SEM analysis and LA-ICPMS analysis along profiles. We use hierarchical clustering based on major and trace elements to objectively identify compositional groups for each chemical profile. By reducing the complexity of chemical zoning to one dimension (i.e. cluster number) we can trace the evolution of the conditions of growth and identify rejuvenation events.</p><p>Alkali feldspar megacrysts (up to 20 cm in size) from the Cathedral Peak unit of the Tuolumne Intrusive Complex occur predominantly disperse and only make between 8 - 12 % of the total crystal population. They are mostly homogeneous in major element, and markedly oscillatory zoned in trace elements such as Ba, Sr, and Rb. Using hierarchical clustering we identify four different chemical groups within the alkali feldspar crystals. Each chemical group is repeated multiple times in a single crystal. Overall the crystals show a decreasing trend of Ba towards the rim. Extended alkali feldspar crystallization would lead to a depletion of Ba in the melt and consequently to the growth of low Ba-zones of alkali feldspar. In some crystals the sequence of decreasing Ba is repeated twice. We propose that this reflects melt recharge in a melt-rich magmatic system.</p>

scholarly journals DISTRIBUTION OF CHEMICAL ELEMENTS IN SOIL FROM CRN DRIM RIVER BASIN, REPUBLIC OF MACEDONIA

2019 ◽  
Vol 40 (1) ◽  
pp. 73 ◽  
Author(s):  
Trajče Stafilov ◽  
Robert Šajn ◽  
Ivana Mickovska
Keyword(s):  
River Basin ◽  
Inductively Coupled Plasma ◽  
Chemical Elements ◽  
Soil Samples ◽  
Emission Spectrometry ◽  
Natural Occurrence ◽  
Plasma Atomic Emission Spectrometry ◽  
Distribution Maps ◽  
Republic Of Macedonia ◽  
Anthropogenic Element

The aim of this study was to investigate the distribution of chemical elements in topsoil and subsoil, focusing on the identification of natural and anthropogenic element sources in the area of the Crn Drim River Basin, Republic of Macedonia. For that purpose, by using sampling network of 5 × 5 km, 124 soil samples from 62 locations (topsoil and bottom soil) were collected. In total 60 elements were analysed, from which 18 elements (Ag, Al, B, Ba, Ca, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, P, Pb, V и Zn) were analysed by inductively coupled plasma - atomic emission spectrometry (ICP-AES) and an additional 42 elements were analysed by ICP - mass spectrometry (ICP-MS). Multivariate statistical analysis was applied to the obtained data. Factor analysis applied to the ICP-AES results produced four geogenic fac-tors: F1 (Ba and K); F2 (Ag, Cd, Cu, Ni, Pb and Zn), F3 (Cr, Fe, Na, Ni and V) and F4 (Al, Ca, Mg and Mn). Data ob-tained from the distribution maps and data analysis on soil samples, indicate the natural occurrence of the analysed ele-ments as well as low concentrations of heavy metals in the studied area.

Geochronology and geochemistry of igneous rocks in the southeastern Lesser Xing’an Range, northeastern China: petrogenesis and implications for the early Mesozoic tectonic evolution

2020 ◽  
Vol 57 (4) ◽  
pp. 506-523
Author(s):  
Jin-hua Qin ◽  
Cui Liu ◽  
Jin-fu Deng
Keyword(s):  
Field Strength ◽  
Inductively Coupled Plasma ◽  
High Field ◽  
Magma Mixing ◽  
Tectonic Setting ◽  
Alkali Feldspar ◽  
Igneous Rocks ◽  
Geochemical Data ◽  
High Field Strength ◽  
Alkaline Granite

We present systematic U–Pb age data collected by laser ablation multi-collector inductively coupled plasma mass spectrometry, precise geochemical data, and Nd isotope data for igneous rocks from the southeastern Lesser Xing’an Range (SE LXR). The results indicate that the formation ages as follows: Maojiatun alkaline granite, 207.2 ± 0.84 Ma and 204.6 ± 0.93 Ma; Diorite porphyrite, 164.5 ± 0.97 Ma; and Tieli syenogranite, 186.7 ± 1.50 Ma. The alkaline granite has high silicon, potassium, alkali, and FeOT contents; it is enriched in high field strength elements, Zr, Hf, Th, Rb, and U; is depleted in Ba, Sr, Nb, Ta, P, Ti, etc.; and has high ratios of 10000Ga/Al. It shows an A2-type granite affinity. The Tieli alkali-feldspar granite has high total alkali contents and is enriched in high field strength elements and rare earth elements and depleted in Sr, Ba, Ti, and P, and shows varying degrees of alkalinity. Rocks from SE LXR display similar εNd (t) values with corresponding to Nd model ages of 1095 to 813 Ma. The igneous rocks from the SE LXR are proposed to be derived from melting of the Neoproterozoic lower crust and potential magma mixing with ancient crystalline basement. The formation of the Maojiatun alkaline granite occurred in response to a postorogenic event following the closure of the Paleo-Asian Ocean. However, the SE LXR exhibited an extensional back-arc tectonic setting in the Early Jurassic. The Middle Jurassic diorite porphyrite could be related to the temporary stagnation of the westward subduction of the Paleo-Pacific plate.

scholarly journals Petrologic Insights into Rift Zone Magmatic Interactions from the 2011 Eruption of Kīlauea Volcano, Hawaiʻi

2019 ◽  
Vol 60 (11) ◽  
pp. 2051-2075
Author(s):  
Brett H Walker ◽  
Michael O Garcia ◽  
Tim R Orr
Keyword(s):  
Trace Element ◽  
Rift Zone ◽  
Magma Mixing ◽  
Major And Trace Elements ◽  
Kilauea Volcano ◽  
The Other ◽  
Least Squares Regression ◽  
Mixing Processes ◽  
Residual Magma ◽  
Kīlauea Volcano

Abstract The high frequency of historical eruptions at Kīlauea Volcano presents an exceptional opportunity to address fundamental questions related to the transport, storage, and interaction of magmas within rift zones. The Nāpau Crater area on Kīlauea’s East Rift Zone (ERZ) experienced nine fissure eruptions within 50 years (1961–2011). Most of the magma intruded during these frequent eruptions remained stored within the rift zone, creating a potential magma mixing depot within the ERZ. The superbly monitored and sampled 2011 eruption (Puʻu ʻŌʻō episode 59) presents an extraordinary opportunity to evaluate magma mixing processes within the ERZ. Whole-rock, glass, and olivine compositions were determined, not only for lava from the 2011 eruption, but also for a new suite of Nāpau Crater area samples from the 1963, 1965, 1968, 1983, and 1997 eruptions, as well as the previously undocumented 1922 eruption. Whole-rock XRF data revealed two geochemically distinct magma batches for episode 59: one less evolved (∼6·6 wt % MgO, 0·46 wt % K2O) than the other (∼6·2 wt % MgO, 0·58 wt % K2O). Episode 59 lava is remarkably aphyric (∼0·1 vol. % phenocrysts), making use of mineralogy to identify parent magma affinities problematic. Linear compositional trends of whole-rock major and trace elements, and reversely zoned olivine crystals indicate episode 59 lavas underwent magma mixing. Least squares regression calculations and plots of major and trace element data, were used to evaluate whether the episode 59 samples are products of mixing summit-derived magma with residual magma from previous Nāpau Crater area eruptions. The regression results and trace element ratios are inconsistent with previously proposed mixing scenarios, but they do support mixing between summit-derived magma and residual magma from the 1983 and 1997 Nāpau Crater area eruptions. These magmas were stored in physically and chemically distinct pods at depths of 1·6–3·0 km prior to mixing with new magma intruded from the summit to produce the episode 59 lava. One pod contained a fractionated equivalent of 1983 lava, and the other a hybrid of compositions similar to 1983 and 1997 lavas. The petrology of episode 59 lava demonstrates that magmas from two previous eruptions (1983 and 1997) were available to mix with magma intruded from the summit region. This study clarifies the pre-eruptive history of the mixed episode 59 lava, and elucidates the evolution of the volcano's magmatic system in a region of frequent eruptions.

Distribution of gallium between phenocrysts and melt in peralkaline salic volcanic rocks, Kenya Rift Valley

2010 ◽  
Vol 74 (2) ◽  
pp. 351-363 ◽  
Author(s):  
R. Macdonald ◽  
N. W. Rogers ◽  
B. Bagiński ◽  
P. Dzierżanowski
Keyword(s):  
Rift Valley ◽  
Inductively Coupled Plasma ◽  
Magma Mixing ◽  
Volcanic Rocks ◽  
Alkali Feldspar ◽  
Volcanic Complex ◽  
Kenya Rift ◽  
Inductively Coupled ◽  
Plasma Mass Spectrometry ◽  
Kenya Rift Valley

AbstractGallium abundances, determined by laser ablation-inductively coupled plasma-mass spectrometry, are presented for phenocrysts and glassy matrices from a metaluminous trachyte and five peralkaline rhyolites from the Greater Olkaria Volcanic Complex, Kenya Rift Valley. Abundances in the glasses range from 28.9 to 33.3 ppm, comparable with peralkaline rhyolites elsewhere. Phenocryst Ga abundances (in ppm) are: sanidine 31.5–45.3; fayalite 0.02–0.22; hedenbergite 3.3–6.3; amphibole 12; biotite 72; ilmenite 0.56–0.72; titanomagnetite 32; chevkinite-(Ce) 364. The mafic phases and chevkinite-(Ce) are enriched in Ga relative to Al, whereas Ga/Al ratios in sanidine are smaller than in coexisting glass. Apparent partition coefficients range from <0.01 in fayalite to 12 in chevkinite-(Ce). Coefficients for hedenbergite, ilmenite and titanomagnetite decrease as melts become peralkaline. The sharp increase in Ga/Al in the more fractionated members of alkaline magmatic suites probably results from alkali feldspar-dominated fractionation. Case studies are presented to show that the Ga/Al ratio may be a sensitive indicator of such petrogenetic processes as magma mixing, interaction of melts with F-rich volatile phases, mineral accumulation and volatile-induced crustal anatexis.

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