Trace element partition coefficients and petrogenesis of the 154 ka dacitic Haramul Mic lava dome (Ciomadul, Romania)

2021 ◽  
Author(s):  
Emese Pánczél ◽  
Maurizio Petrelli ◽  
Réka Lukács ◽  
Szabolcs Harangi
Keyword(s):  
Trace Element ◽  
Partition Coefficients ◽  
Lava Dome ◽  
Bulk Composition ◽  
Volcanic Complex ◽  
Elevated Concentration ◽  
Positive Anomaly ◽  
Accessory Zircon ◽  
Eruption Age ◽  
Li Content

<p>Haramul Mic is a ~0.15 km<sup>3 </sup>volume, crystal-rich, homogeneous, high-K dacite lava dome, which is one of the oldest ones in the Ciomadul Volcanic Complex (Romania, eastern-central Europe). The eruption that formed the lava dome occurred after about 200.000 years of quiescence. Eruption age of the dome determined by (U-Th)/He dating on zircon gave 154 +/- 16 ka that is in agreement with the youngest zircon U-Th outer rim date (142 +18/-16 ka). The apparently continuous crystallization of zircon between the eruption age and the 306 +/- 37 ka oldest zircon core date records a long-living magmatic plumbing system.</p><p>The Haramul Mic lava dome rock has 35-40% average crystal content and consists of plagioclase, amphibole, biotite and accessory zircon, apatite, titanite and Fe-Ti oxides. The groundmass is mainly built up by perlitic glass with some microlites and sheared vesicles. The dacite contains sparse mafic enclaves with K-rich, shoshonitic bulk composition, composed of plagioclase and biotite in addition to less amount of amphibole. Felsic crystal clots are more common and they comprise plagioclase, amphibole, biotite and interstitial vesicular glass.</p><p>Trace element content of the mineral phases and the groundmass glass was determined by LA-ICP-MS. All of the studied phases show homogeneous trace element compositions and along with the textural characteristics these imply general equilibrium state in the magma storage system before the eruption. Amphibole-plagioclase geothermometer and geobarometer calculations result in 700-800 <sup>o</sup>C crystallization temperature and 200-300 MPa crystallization pressure.</p><p>In order to reveal the magma chamber processes that triggered the eruption and formed the Haramul Mic lava dome after long quiescence time, it is necessary to understand better the behaviour of trace elements as the most sensitive indicators of magma reservoir mechanisms. We determined mineral-liquid trace element partition coefficients and evaluated the result in the context of crystal lattice strain model. They show many similarities with those proposed for the Fish Canyon Tuff dacite except for Li and Sc. The anomalous behaviour of Sc is clearly expressed by the elevated concentration in the glass phase and many times, there are some zonation in Sc from crystal core to rim. This could be explained either by inherently higher Sc content of the melt reflecting the nature of the primary magmas or by partial remelting of biotite just before the eruption. Significant positive anomaly of Li content can be observed in biotite crystals of the mafic enclave compared with the dacitic host rock. Li content of plagioclase varies between 15-30 ppm with slight rimward depletion.</p><p>Eruption initiation cannot be explained by physical mixing of mafic recharge magma, but rather by volatile transfer or second boiling. The water-rich nature of the melt is reflected by the abundant vesicles in the glassy groundmass. Furthermore, the amphibole phenocrysts have sharp margin without resorption rim, which suggest hydrous melt phase and relatively fast magma ascent.</p><p>This research belongs to the NKFIH-OTKA K135179 project and was supported by the ÚNKP-19-1 New National Excellence Program of the Ministry for Innovation and Technology.</p>

The ’Little’ Fish Canyon Tuff in Romania: Rejuvenation of granodioritic crystal mush resulting in homogeneous dacite recorded by the Haramul Mic lava dome (Ciomadul)

2020 ◽  
Author(s):  
Emese Pánczél ◽  
Maurizio Petrelli ◽  
Réka Lukács ◽  
Szabolcs Harangi
Keyword(s):  
Lava Dome ◽  
Thermal Evolution ◽  
Bulk Composition ◽  
Volcanic Complex ◽  
Bulk Rock ◽  
Crystal Mush ◽  
Magmatic System ◽  
Zircon Core ◽  
Accessory Zircon ◽  
Zircon Crystallization

<p>Long-dormant volcanoes (quiescence time is several 100’s to 10’s thousand years between eruptions) pose a particular hazard, since the long repose time decreases the awareness and there is mostly a lack of monitoring. The Haramul Mic, a pancake-shaped flat dacitic lava dome is part of the Ciomadul Volcanic Complex in eastern-central Europe (Romania) and serves as an excellent example of such volcanoes. The Haramul Mic lava dome is the earliest product of the Young Ciomadul Eruption Period (YCEP), when the activity recrudesced in the area after about 200.000 years quiescence time. Eruption age of the dome determined by (U-Th)/He dating on zircon gave 154 +/- 16 ka that is in agreement with the youngest zircon U-Th outer rim date (142 +18/-16 ka). In the YCEP zircon crystallization dates record typically long, up to 350-400 kyr lifetime of the magmatic plumbing system, in case of  Haramul Mic the oldest zircon core is 306 +/- 37 ka old.</p><p>The 880.7 m high lava dome covers an area of 1.1 km<sup>2</sup> and has a volume of ~0.15 km<sup>3</sup>. It is composed of crystal-rich homogeneous high-K dacite. The average crystal content is 35-40% and consists of plagioclase, amphibole, biotite and accessory zircon, apatite, titanite and Fe-Ti oxides. The groundmass is mainly built up by perlitic glass with some microlites. The dacite includes mafic enclaves having plagioclase and amphibole besides a large amount of biotite crystals, that eventuates K-rich, shoshonitic bulk composition. The dacite contains abundant felsic crystal clots which comprise plagioclase, amphibole, biotite and interstitial vesicular glass.</p><p>Amphiboles are relatively homogeneous in chemical composition. They are low-Al hornblendes suggesting 700-800 <sup>o</sup>C crystallization condition at 200-300 MPa compared with experimental data. Al-in-hornblende geobarometer and amphibole-plagioclase geothermometer calculations give results reproducing these temperature and pressure ranges. Although the Kis-Haram dacite is fairly rich in 25-45 anorthite mol% plagioclase, no negative Eu anomaly can be observed in the bulk rock and the glass. Similarities between Fish Canyon Tuff and Kis-Haram rocks can be strikingly noted regarding the major and trace element contents of mineral phases, glass and bulk rock that all refer to a wet oxidised calc-alkaline magmatic system. The relatively small volume Kis-Haram lava dome represents a rejuvenated low-temperature granodioritic crystal mush having similar features as the large volume silicic eruption of Fish Canyon Tuff. Their recorded almost similarly long zircon crystallization intervals give an interesting aspect with regard to the thermal evolution of the magmatic system and eruption volumes.</p><p>This research was financed by the Hungarian National Research, Development and Innovation Fund (NKFIH) within No. K116528 project and was supported by the ÚNKP-19-1 New National Excellence Program of the Ministry for Innovation and Technology.</p>

Magmatic evolution of zoned and unzoned ignimbrites: evidence for a complex crustal architecture feeding four rapid-sequence, caldera-forming eruptions in the San Juan Mountains, Colorado

2021 ◽  
Author(s):  
Adam Curry ◽  
Luca Caricchi ◽  
Peter W Lipman
Keyword(s):  
Trace Element ◽  
The Other ◽  
San Juan ◽  
Volcanic Complex ◽  
Accessory Zircon ◽  
San Juan Mountains ◽  
Reservoir Architecture ◽  
Magma Reservoirs ◽  
Magmatic Body ◽  
Mineral Assemblages

Abstract The last four caldera-forming ignimbrites in the central San Juan caldera cluster, Colorado, erupted 1,400 km3 in ≤ 80 k.y. and alternated between zoned crystal-poor rhyolite to crystal-rich dacite and unzoned, crystal-rich dacite. The zoned 150 km3 Rat Creek Tuff (26.91 Ma), unzoned 250 km3 Cebolla Creek Tuff, and zoned 500 km3 Nelson Mountain Tuff (26.90 Ma) formed the nested San Luis caldera complex with slightly offset calderas, and the unzoned 500 km3 Snowshoe Mountain Tuff (26.87 Ma) formed the Creede caldera to the south. The Rat Creek Tuff, Nelson Mountain Tuff, and Snowshoe Mountain Tuff have similar mineral assemblages of plagioclase, sanidine, quartz, biotite, hornblende, clinopyroxene, Fe-Ti oxides, and accessory zircon, titanite, and apatite. The Cebolla Creek Tuff differs from the other three ignimbrites with more abundant hornblende and lack of quartz and sanidine. Trace element compositions of interstitial glass are unique to each ignimbrite, correlating with mineral assemblages and inferred crystallization depths. Glass, feldspar, hornblende, and clinopyroxene thermobarometry calculations provide evidence for vertically extensive crustal magma reservoirs with a common magmatic zone at ∼435-470 MPa (∼16-17 km) transitioning into shallow pre-eruptive reservoirs between ∼110-340 MPa (∼4-13 km), similar to the estimated magma reservoir architecture of the Altiplano Puna Volcanic Complex. The upper portions of the eruptible parts of the magma reservoirs of the Rat Creek Tuff (215 ± 50 MPa/∼810-820 °C), Cebolla Creek Tuff (340 ± 20 MPa/∼860-880° C), Nelson Mountain Tuff (215 ± 20 MPa/∼745-800 °C), and Snowshoe Mountain Tuff (110 ± 40 MPa/825 ± 10 °C) occupied shallow levels in the crust similar to other magma reservoirs of the central San Juan caldera complex. Trace element modelling correlates with a deep crystallization signature in the unzoned Cebolla Creek Tuff and Snowshoe Mountain Tuff, typified by a flat trend in Ba versus Sr whole-rock and glass chemistry. The zoned Rat Creek Tuff and Nelson Mountain Tuff are typified by a steep trend in Ba versus Sr chemistry interpreted as a shallower crystallization signature. Similarly, the unzoned Cebolla Creek Tuff and Snowshoe Mountain Tuff have flatter slopes in FeO versus An space of plagioclase chemistry interpreted as more abundant deep plagioclase crystallization and a difficulty to physically mix with Fe-rich mafic recharge magma due to higher viscosity. The zoned Rat Creek Tuff and Nelson Mountain Tuff have higher slopes in FeO versus An space of plagioclase chemistry interpreted as more abundant shallow plagioclase crystallization and more feasible mixing with Fe-rich mafic recharge magma due to lower viscosity. The eruption of the Rat Creek Tuff was likely triggered by mafic injection, but the other three ignimbrites lack mingling textures in pumice, suggesting that other mechanisms were important in causing such large eruptions. After a prolonged period of mantle-derived magma injection and crustal heating (∼25,000 km3 Conejos Formation erupted during ∼35-29 Ma), the San Juan magmatic body became a robust and versatile producer of diverse eruptible magmas in short time periods during its Oligocene ignimbrite flare-up.

scholarly journals Tephrostratigraphy and Magma Evolution Based on Combined Zircon Trace Element and U-Pb Age Data: Fingerprinting Miocene Silicic Pyroclastic Rocks in the Pannonian Basin

2021 ◽  
Vol 9 ◽  
Author(s):  
Réka Lukács ◽  
Marcel Guillong ◽  
Olivier Bachmann ◽  
László Fodor ◽  
Szabolcs Harangi
Keyword(s):  
Trace Element ◽  
Partition Coefficients ◽  
Pannonian Basin ◽  
Trace Element Content ◽  
Element Content ◽  
Published Data ◽  
Concentration Data ◽  
Pyroclastic Deposits ◽  
Silicic Volcanic ◽  
Melt Composition

We present a novel approach to use zircon as a correlation tool as well as a monitor for magma reservoir processes in silicic volcanic systems. Fingerprinting eruption products based on trace element content and U-Pb dates of zircon offers a promising, previously underestimated tephra correlation perspective, particularly in cases where the main minerals and glass are altered. Using LA-ICP-MS analyses, a rapid and cost-effective method, this study presents U-Pb dates and trace element concentration data of more than 950 zircon crystals from scattered occurrences of early to mid-Miocene silicic ignimbrites in the northern Pannonian Basin, eastern-central Europe. This magmatic phase produced >4000 km3 of erupted material, which provide unique stratigraphic marker horizons in central and southern Europe. The newly determined zircon U-Pb eruption ages for the distal pyroclastic deposits are between 17.5 and 14.3 Ma, comparable with the previously published ages of the main eruptive events. Multivariate discriminant analysis of selected trace element concentrations in zircon proved to be useful to distinguish the main volcanic units and to correlate the previously ambiguously categorized pyroclastic deposits with them. Using the zircon trace element content together with published glass data from crystal-poor ignimbrites, we determined the zircon/melt partition coefficients. The obtained values of the distinct eruption units are very similar and comparable to published data for silicic volcanic systems. This suggests that zircon/melt partition coefficients in calc-alkaline dacitic to rhyolitic systems are not significantly influenced by the melt composition at >70 wt% SiO2 at near solidus temperature. The partition coefficients and zircon trace element data were used to calculate the equilibrium melt composition, which characterizes the eruption products even where glass is thoroughly altered or missing. Hence, our results provide important proxies for tephrostratigraphy in addition to yielding insights into the complex processes of silicic magma reservoirs.

scholarly journals Supplemental Material: Petrogenesis of Ordovician granitoids in Western Kunlun, NW Tibetan Plateau: Insights into the evolution of the Proto-Tethys Ocean

2020 ◽  
Author(s):  
Peng Wang ◽  
Guochun Zhao ◽  
et al.
Keyword(s):  
Tibetan Plateau ◽  
Trace Element ◽  
Partition Coefficients ◽  
Hf Isotope ◽  
Igneous Rocks ◽  
Pb Isotope ◽  
Element Modeling ◽  
Western Kunlun ◽  
Tethys Ocean ◽  
Ordovician Granitoids

Table S1: Zircon U-Pb ages of igneous rocks in the Western Kunlun orogenic belt; Table S2: Results of whole-rock major- (wt%) and trace-element (ppm) data from the three intrusions; Table S3: Zircon U-Pb age of the three intrusions; Table S4: Zircon Hf isotope compositions of the three intrusions; Table S5: Whole-rock Sr-Nd-Pb isotope compositions of the three intrusions; Table S6: Representative analyses of feldspar, amphibole, and pyroxene from the Aqiang and Yutian intrusions; Table S7: Bulk partition coefficients used for trace-element modeling in Figure 14; Figure S1: CL images of zircons showing internal textures and ages of 206Pb/238U (Ma).

Dating polymetamorphism using titanite: Linking trace elements, textures, and ages

2021 ◽  
Author(s):  
Jesse Walters ◽  
Alicia Cruz-Uribe ◽  
Won Joon Song ◽  
Joshua Stone ◽  
Hanna Brooks ◽  
...  
Keyword(s):  
Trace Elements ◽  
Trace Element ◽  
Bulk Composition ◽  
Granulite Facies ◽  
Compositional Variation ◽  
Excimer Laser Ablation ◽  
Eu Anomaly ◽  
Fluid Infiltration ◽  
Icp Ms ◽  
The University

<p>Here we present titanite U-Pb dates from two banded calc silicate gneisses (SSP18-1A and 1B) from western Maine. Mineral textures and compositions display multiple phases of metamorphism. The peak lower granulite facies assemblage is Di + Kfs + Pl + Ttn, with little to no calcite present. Late Czo + Tr replaces Di + Pl, suggesting an influx of X<sub>H2O</sub> > 0.90 fluids. Nearby metapelites show the transition from sillimanite-bearing to muscovite-bearing assemblages, indicating that fluid infiltration may be widespread. Compositional maps of clinopyroxene in SSP18-1B show fracturing and rehealing of early Fe-rich diopside with late Mg-rich diopside. Both samples exhibit overprinting of An-rich plagioclase by increasingly Ab-rich plagioclase. Titanite grains in both samples exhibit BSE textures and compositional variation consistent with multiple phases of growth and dissolution-reprecipitation reactions.</p><p>Titanite trace element and U-Pb data were collected by LA-ICP-MS at the University of Maine using an ESI NWR193<sup>UC</sup> excimer laser ablation system coupled to an Agilent 8900 ICP-MS. Single spot ages range from 280 to 400 Ma with 12-20 Ma propagated 2SE. Four composition-date domains are identified in SSP18-1B: A. 400 ± 8 Ma (dark BSE cores), B. 372 ± 4 Ma (bright BSE cores), C. 342 ± 6 Ma (bright BSE cores, no Eu anomaly), and D. 302 ± 3 Ma (dark BSE rims, low LREE). Titanite Fe and Y concentrations increase with decreasing date, whereas Sr concentrations decrease. In clinopyroxene, Fe and Y decrease between high Fe-diopside and late Mg-diopside, placing the fracturing and rehealing events between 400 and 372 Ma. Strontium concentrations in titanite decrease between subsequent generations of plagioclase, diopside, and titanite, suggesting a continual fractionation of Sr from the reactive bulk composition. Low LREE in ca. 300 Ma titanite domains in both samples are consistent with the formation of texturally late allanite and clinozoisite, thus constraining the timing of the high X<sub>H2O</sub> fluid infiltration event. Zr-in-titanite temperatures for rims in the quartz-bearing SSP18-1B give a weighted mean T of 764 °C at 4.5 GPa, consistent with the muscovite-absent sillimanite-bearing assemblage in garnet cores from metapelite samples. However, the 100-150 °C lower Grt-Bt temperatures for metapelites are not consistent with peak metamorphic phase equilibria. Our data demonstrate the utility of linking titanite textures and trace element concentrations with those of other minerals to reveal past metamorphic and deformational events. Additionally, we show that titanite may reliably preserve U and Pb isotopic ratios, trace elements, and textures over subsequent high-T metamorphic events.</p>

Factors affecting the trace element partition coefficients between coexisting sulfides

1970 ◽  
Vol 65 (7) ◽  
pp. 815-837 ◽  
Author(s):  
P. Ghosh-dastidar ◽  
G. E. Pajari ◽  
L. T. Trembath
Keyword(s):  
Trace Element ◽  
Partition Coefficients ◽  
Factors Affecting

Evolution of the Miscibility Gap Between Muscovite and Biotite Solid Solutions with Increasing Lithium Content: An Experimental Study in the System K2O-Li2O-MgO-FeO-Al2O3-SiO2-H2O-HF at 600°C, 2 kbar PH2O: Comparison with Natural Lithium Micas

1986 ◽  
Vol 50 (358) ◽  
pp. 641-651 ◽  
Author(s):  
Gilles Monier ◽  
Jean-Louis Robert
Keyword(s):  
Experimental Study ◽  
Bulk Composition ◽  
Experimental Studies ◽  
Fluorine Content ◽  
Interplanar Distance ◽  
Miscibility Gap ◽  
Lithium Content ◽  
Free System ◽  
Naturally Occurring ◽  
Li Content

AbstractThis paper presents the results of an experimental study of the miscibility gap between trioctahedral and dioctahedral micas in the system K2O Li2O-MgO-FeO-Al2O3-SiO2-H2O-HF at 600°C under 2 kbar PH2O. The existence of this miscibility gap is known from previous experimental studies. The gap is large in the lithium-free system; its width reduces progressively with increasing Li content; for sufficient Li contents (Li > 0.6 atom per formula unit, based on 11 oxygens), a single Li-mica phase is obtained, intermediate between trioctahedral and dioctahedral micas. Any bulk composition located inside the miscibility gap gives an assemblage of two micas, one of the biotite-type and one of the muscovite-type. All the compositions located outside the gap, and, in particular, those belonging to the joins phlogopite-trilithionite and muscovite-zinnwaldite (or its magnesian equivalent) give a single mica phase, provided that the fluorine content is sufficient. The ratio Li/F ≈ 1 is a convenient suitable value. The types of micas and the evolutions of their compositions are well characterized by their interplanar distance d060. These experimental results allow the interpretation of most compositions of naturally occurring lithium micas, in the range 0 ⩽ Li ⩽ 1 a./f.u. Natural micas of biotite-type and muscovite-type are located on both sides of the miscibility gap and their compositions get closer with increasing Li content.

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