scholarly journals Gore Mountain Garnet Amphibolite records UHT Conditions: Implications for the Rheology of the Lower Continental Crust During Orogenesis

2021 ◽  
Author(s):  
William J Shinevar ◽  
Oliver Jagoutz ◽  
Jill A VanTongeren
Keyword(s):  
Inductively Coupled Plasma ◽  
Diffusion Models ◽  
Hydration Reaction ◽  
Garnet Amphibolite ◽  
Grenville Province ◽  
Inductively Coupled ◽  
Trace Element Chemistry ◽  
Plasma Mass Spectrometry ◽  
Lower Crustal ◽  
Petrographic Study

Abstract The Gore Mountain Garnet Amphibolite (GMGA), part of the Mesoproterozoic Grenville province in the Adirondack Highlands, NY, USA, is an iconic rock type known for hosting the world’s largest garnets (up to 1 m diameter). We present a new detailed petrographic study of these rocks. Field relations, whole rock, and mineral major and trace element chemistry suggest that these rocks formed via a prograde hydration reaction of a metagabbro during an increase in pressure and temperature. Laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) U-Pb geochronology applied to zircon interpreted to be metamorphic in origin dates this reaction to 1053.9±5.4 Ma (2σ; MSWD = 0.94), during the Ottawan Orogeny (1090-1020 Ma). Our results on peak metamorphic P-T conditions based on thermobarometry, diffusion models, and thermodynamic modelling indicate that these rocks formed at ultra-high temperature (UHT, >900˚C) conditions (P = 9–10 kbar, T = 950±40˚C), significantly hotter than previously estimated. Diffusion models pinned by nearby cooling ages require the GMGA to initially cool quickly (9.1 ˚C Myr<su-1p>), followed by slower cooling (2.6 ˚C Myr<su-1p>). The two-stage cooling history for the GMGA could reflect initial advection-dominated cooling followed by conduction-dominated cooling once flow ceases. Our results suggest that the region was hot enough to undergo topography-driven lower crustal flow similar to that hypothesized for modern Tibet for 20–0 Myr (25–0 Myr when the effects of melt are included).

scholarly journals Coupled Substitutions of Minor and Trace Elements in Co-Existing Sphalerite and Wurtzite

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 147 ◽  
Author(s):  
Allan Pring ◽  
Benjamin Wade ◽  
Aoife McFadden ◽  
Claire E. Lenehan ◽  
Nigel J. Cook
Keyword(s):  
Trace Element ◽  
Inductively Coupled Plasma ◽  
Significant Variation ◽  
Inductively Coupled ◽  
Trace Element Chemistry ◽  
Icp Ms ◽  
Two Samples ◽  
Coupled Substitution ◽  
Plasma Mass Spectrometry ◽  
Growth Zoning

The nature of couple substitutions of minor and trace element chemistry of expitaxial intergrowths of wurtzite and sphalerite are reported. EPMA and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analyses display significant differences in the bulk chemistries of the two epitaxial intergrowth samples studied. The sample from the Animas-Chocaya Mine complex of Bolivia is Fe-rich with mean Fe levels of 4.8 wt% for wurztite-2H and 2.3 wt% for the sphalerite component, while the sample from Merelani Hills, Tanzania, is Mn-rich with mean Mn levels in wurztite-4H of 9.1 wt% and for the sphalerite component 7.9 wt% In both samples studied the wurtzite polytype is dominant over sphalerite. LA-ICP-MS line scans across the boundaries between the wurtzite and sphalerite domains within the two samples show significant variation in the trace element chemistries both between and within the two coexisting polytypes. In the Merelani Hills sample the Cu+ + Ga3+ = 2Zn2+ substitution holds across both the wurztite and sphalerite zones, but its levels range from around 1200 ppm of each of Cu and Ga to above 2000 ppm in the sphalerite region. The 2Ag+ + Sn4+ = 3Zn2+ coupled substitution does not occur in the material. In the Animas sample, the Cu+ + Ga3+ = 2Zn2+ substitution does not occur, but the 2(Ag,Cu)+ + Sn4+ = 3Zn2+ substitution holds across the sample despite the obvious growth zoning, although there is considerable variation in the Ag/Cu ratio, with Ag dominant over Cu at the base of the sample and Cu dominant at the top. The levels of 2(Ag,Cu)+ + Sn4+ = 3Zn2+ vary greatly across the sample from around 200 ppm to 8000 ppm Sn, but the higher values occur in the sphalerite bands.

The construction of the Donegal composite batholith, Irish Caledonides: Temporal constraints from U-Pb dating of zircon and titanite

2021 ◽  
Author(s):  
Donnelly B. Archibald ◽  
Lauren M.G. Macquarrie ◽  
J. Brendan Murphy ◽  
Robin A. Strachan ◽  
Chris R.M. McFarlane ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Early Devonian ◽  
Mafic Enclaves ◽  
Inductively Coupled ◽  
Deep Crust ◽  
Icp Ms ◽  
Plasma Mass Spectrometry ◽  
Growth Zones ◽  
Incremental Construction ◽  
Lower Crustal

Magmatic and tectonic processes can transport large volumes of magma generated in the deep crust as discrete pulses to shallower crustal depths, resulting in the incremental construction of large, composite batholiths over thousands to tens of millions of years. The Silurian to Early Devonian Donegal composite batholith in Ireland is a classic example of which regional geological syntheses and lithogeochemical data show that emplacement was syn- and post-kinematic with respect to the terminal phases (ca. 437−415 Ma) of the Caledonian orogeny. We used U-Pb dating of zircon and titanite to investigate the construction of the batholith over time. Imaging of these minerals reveals complex, zoned grains with distinct autocrystic (growth during pluton emplacement) and antecrystic (growth during lower crustal incubation) domains as well as xenocrysts (incorporated from wall rocks). To determine the ages of emplacement and of inherited domains, discrete growth zones were targeted for dating using laser ablation−inductively coupled plasma−mass spectrometry (LA-ICP-MS). Taken together, the zircon and titanite U-Pb isotopic data indicate that magmatism occurred over at least 30 m.y., between ca. 430 Ma and 400 Ma. Batholith emplacement is bracketed by the ca. 427−423 Ma Ardara pluton and the latest phases in the Main Donegal and Trawenagh Bay plutons (ca. 400 Ma). Although apparently volumetrically minor, U-Pb data from spatially associated mafic rocks (appinite suite, lamprophyre dikes, and mafic enclaves in granitoid plutons) yield ages ranging from ca. 431−416 Ma, which indicates ongoing mafic magmatism during emplacement of much of the Donegal composite batholith.

Laser ablation split stream for in situ sulfur isotope and elemental analysis

2021 ◽  
Author(s):  
Marcus Oelze ◽  
Daniel A. Frick ◽  
Sarah A. Gleeson
Keyword(s):  
Laser Ablation ◽  
Inductively Coupled Plasma ◽  
Sulfur Isotope ◽  
Femtosecond Laser Ablation ◽  
Inductively Coupled ◽  
Trace Element Chemistry ◽  
Icp Ms ◽  
Plasma Mass Spectrometry ◽  
Selection Of

In situ sulfur (S) isotope ratios and trace element chemistry were simultaneously determined in a wide selection of different (natural) sulfides and sulfates using femtosecond laser ablation split stream (fsLASS) inductively coupled plasma mass spectrometry (ICP-MS).

scholarly journals U-Pb Age and Hf Isotope Systematics of Zircon from Eclogite Xenoliths in Devonian Kimberlites: Preliminary Data on the Archaean Roots in the Junction Zone between the Sarmatian and Fennoscandian Segments of the East European Platform

Geosciences ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 487
Author(s):  
Leonid Shumlyanskyy ◽  
Stepan Tsymbal ◽  
Monika A. Kusiak ◽  
Simon A. Wilde ◽  
Alexander A. Nemchin ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Inductively Coupled Plasma ◽  
East European Platform ◽  
Hf Isotope ◽  
Junction Zone ◽  
Karelian Craton ◽  
East European ◽  
Inductively Coupled ◽  
Plasma Mass Spectrometry ◽  
Lower Crustal

The results of a laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U–Pb dating and a Hf isotope study of zircon crystals separated from small eclogite xenoliths found in Devonian kimberlites within the Prypyat horst, Ukraine, have been reported. The studied area is located in the junction zone between the Sarmatian and Fennoscandian segments of the East European Platform. Four laser ablation sites on two zircon grains yielded Paleoproterozoic U–Pb ages between 1954 ± 24 and 1735 ± 54 Ma. In contrast, three of four Hf sites revealed negative εHf values and Paleoarchean to Mesoarchean model ages, excluding the possibility that the eclogite xenoliths represented segments of a juvenile Paleoproterozoic subducted slab or younger mafic melts crystallized in the subcontinental lithospheric mantle. A single laser ablation Hf spot yielded a positive εHf value (+3) and a Paleoproterozoic model age. Two models for eclogite origin can be proposed. The first foresees the extension of the Archean lower-crustal or lithospheric roots beneath the Sarmatia–Fennoscandia junction zone for over 200 km from the nearest known outcrop of Archean rocks in the Ukrainian Shield. The second model is that the Central Belarus Suture Zone represents a rifted-out fragment of the Kola–Karelian craton that was accreted to Sarmatia before the actual collision of these two segments of Baltica.

Metal-Organic Frameworks vs. Buffers: Case Study of UiO-66 Stability

2020 ◽  
Author(s):  
Daniel Bůžek ◽  
Slavomír Adamec ◽  
Kamil Lang ◽  
Jan Demel
Keyword(s):  
Inductively Coupled Plasma ◽  
Buffer Capacity ◽  
Metal Organic Framework ◽  
Metal Organic Frameworks ◽  
Analytical Techniques ◽  
Aqueous Dispersions ◽  
Inductively Coupled ◽  
Plasma Mass Spectrometry ◽  
Metal Organic

<div><p>UiO-66 is a zirconium-based metal-organic framework (MOF) that has numerous applications. Our group recently determined that UiO-66 is not as inert in aqueous dispersions as previously reported in the literature. The present work therefore assessed the behaviour of UiO-66 in buffers: 2-amino-2-(hydroxymethyl)-1,3-propanediol (TRIS), 4-(2-hydroxyethyl)piperazine-1-ethane sulfonic acid (HEPES), N-ethylmorpholine (NEM) and phosphate buffer (PB), all of which are commonly used in many UiO-66 applications. High pressure liquid chromatography and inductively coupled plasma mass spectrometry were used to monitor degradation of the MOF. In each buffer, the terephthalate linker was released to some extent, with a more pronounced leaching effect in the saline forms of these buffers. The HEPES buffer was found to be the most benign, whereas NEM and PB should be avoided at any concentration as they were shown to rapidly degrade the UiO-66 framework. Low concentration TRIS buffers are also recommended, although these offer minimal buffer capacity to adjust pH. Regardless of the buffer used, rapid terephthalate release was observed, indicating that the UiO-66 was attacked immediately after mixing with the buffer. In addition, the dissolution of zirconium, observed in some cases, intensified the UiO-66 decomposition process. These results demonstrate that sensitive analytical techniques have to be used to monitor the release of MOF components so as to quantify the stabilities of these materials in liquid environments.</p></div>

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