2022
61.
Kerraouch, I.; Kebukawa, Y.; Bischoff, A.; Zolensky, M. E.; Wölfer, E.; Hellmann, J. L.; Ito, M.; King, A.; Trieloff, M.; Barrat, J. A.; Schmitt-Kopplin, P.; Pack, A.; Patzek, M.; Hanna, R. D.; Fockenberg, T.; Marrocchi, Y.
In: Geochimica et Cosmochimica Acta, vol. 334, pp. 155–186, 2022.
@article{Kerraouch_etal2022,
title = {Heterogeneous nature of the carbonaceous chondrite breccia Aguas Zarcas -- Cosmochemical characterization and origin of new carbonaceous chondrite lithologies},
author = {I. Kerraouch and Y. Kebukawa and A. Bischoff and M. E. Zolensky and E. W\"{o}lfer and J. L. Hellmann and M. Ito and A. King and M. Trieloff and J. A. Barrat and P. Schmitt-Kopplin and A. Pack and M. Patzek and R. D. Hanna and T. Fockenberg and Y. Marrocchi},
doi = {10.1016/j.gca.2022.07.010},
year = {2022},
date = {2022-01-01},
urldate = {2022-01-01},
journal = {Geochimica et Cosmochimica Acta},
volume = {334},
pages = {155--186},
abstract = {On April 23rd, 2019, the Aguas Zarcas meteorite fall occurred in Costa Rica. Because the meteorite was quickly recovered, it contains valuable extraterrestrial materials that have not been contaminated by terrestrial processes. Our X-ray computed tomography (XCT) and scanning electron microscopy (SEM) results on various pre-rain fragments from earlier work (Kerraouch et al., 2020; 2021) revealed several distinct lithologies: Two distinct metal-rich lithologies (Met-1 and Met-2), a CM1/2 lithology, a C1 lithology, and a brecciated CM2 lithology consisting of different petrologic types. Here, we further examined these lithologies in the brecciated Aguas Zarcas meteorite and report new detailed mineralogical, chemical, isotopic, and organic matter characteristics. In addition to petrographic differences, the lithologies also display different chemical and isotopic compositions. The variations in their bulk oxygen isotopic compositions indicate that the various lithologies formed in different environments and/or under diverse conditions (e.g., water/rock ratios). Each lithology experienced a different hydration period during its evolution. Together, this suggests that multiple precursor parent bodies may have been involved in these processes of impact brecciation, mixing, and re-assembly. The Cr and Ti isotopic data for both the CM1/2 and Met-1 lithology are consistent with those of other CM chondrites, even though Met-1 displays a significantly lower e50Ti isotopic composition that may be attributable to sample heterogeneities on the bulk meteorite scale and may reflect variable abundances of refractory phases in the different lithologies of Aguas Zarcas. Finally, examination of the organic matter of the various lithologies also suggests no strong evidence of thermal events, but a short-term heating cannot completely be excluded. Raman parameters indicate that the peak temperature has been lower than that for Yamato-793321 (CM2, textasciitilde 400 textdegreeC). Considering the new information presented in this study, we now better understand the origin and formation history of the Aguas Zarcas daughter body.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
On April 23rd, 2019, the Aguas Zarcas meteorite fall occurred in Costa Rica. Because the meteorite was quickly recovered, it contains valuable extraterrestrial materials that have not been contaminated by terrestrial processes. Our X-ray computed tomography (XCT) and scanning electron microscopy (SEM) results on various pre-rain fragments from earlier work (Kerraouch et al., 2020; 2021) revealed several distinct lithologies: Two distinct metal-rich lithologies (Met-1 and Met-2), a CM1/2 lithology, a C1 lithology, and a brecciated CM2 lithology consisting of different petrologic types. Here, we further examined these lithologies in the brecciated Aguas Zarcas meteorite and report new detailed mineralogical, chemical, isotopic, and organic matter characteristics. In addition to petrographic differences, the lithologies also display different chemical and isotopic compositions. The variations in their bulk oxygen isotopic compositions indicate that the various lithologies formed in different environments and/or under diverse conditions (e.g., water/rock ratios). Each lithology experienced a different hydration period during its evolution. Together, this suggests that multiple precursor parent bodies may have been involved in these processes of impact brecciation, mixing, and re-assembly. The Cr and Ti isotopic data for both the CM1/2 and Met-1 lithology are consistent with those of other CM chondrites, even though Met-1 displays a significantly lower e50Ti isotopic composition that may be attributable to sample heterogeneities on the bulk meteorite scale and may reflect variable abundances of refractory phases in the different lithologies of Aguas Zarcas. Finally, examination of the organic matter of the various lithologies also suggests no strong evidence of thermal events, but a short-term heating cannot completely be excluded. Raman parameters indicate that the peak temperature has been lower than that for Yamato-793321 (CM2, textasciitilde 400 textdegreeC). Considering the new information presented in this study, we now better understand the origin and formation history of the Aguas Zarcas daughter body.
62.
Avice, G.; Meier, M. M. M.; Marrocchi, Y.
Origin of radiogenic 129Xe variations in carbonaceous chondrites Journal Article
In: Geochemical Perspectives Letters, vol. 23, pp. 1–4, 2022.
@article{Avice_etal2022,
title = {Origin of radiogenic 129Xe variations in carbonaceous chondrites},
author = {G. Avice and M. M. M. Meier and Y. Marrocchi},
doi = {10.7185/geochemlet.2228},
year = {2022},
date = {2022-01-01},
journal = {Geochemical Perspectives Letters},
volume = {23},
pages = {1--4},
abstract = {Noble gases trapped in primitive meteorites (chondrites) allow quantification of the physical processes that operated during the evolution of the protoplanetary disk (e.g., Kuga et al., 2015). Although these elements are present in different carriers contained in meteorites (including presolar SiC, diamonds, graphite; Ott, 2014), they are mainly hosted in a phase \^{a} referred to as phase Q\^{a} whose nature is still poorly characterised (Busemann et al., 2000). Notwithstanding this uncertainty, it has been shown that phase Q dominates the heavy noble gas budget of chondrites and is closely associated with carbonaceous material that survives HF/HCl attack of bulk meteorites (Lewis et al., 1975). Thanks to its extreme sensitivity to oxidation, the xenon isotopic composition of phaseQhas been precisely determined, revealing a mass dependent isotopic fractionation relative to solar wind (SW-Xe) in favour of the heavy isotopes relative to the light ones (Wieler et al., 1991; Busemann et al., 2000; Gilmour, 2010). However, the commonly used Xe-Q isotopic composition hinges on the average of measurements of several carbonaceous chondrites (CCs) showing distinct Xe isotopic compositions between and within each group, especially for 129Xe (Busemann et al., 2000). Such 129Xe excesses result from the decay of extinct 129I (t1/2 = 16 Myr), which was producing radiogenic 129Xe* during the first \^{a}`u100 million years of the solar system (Jeffery and Reynolds, 1961). The measurement of xenon isotopes in the coma of comet 67P/Churyumov-Gerasimenko revealed extreme 129Xe enrichment relative to 132Xe and the solar composition (Marty et al., 2017). As this large monoisotopic excess would require unlikely 129I enrichment, it has been interpreted as originating from a specific nucleosynthetic process producing 129Xe that was sampled by icy bodies formed in the outer solar system (Marty et al., 2017). Interestingly, the carbon-rich primitive chondrites Tagish Lake and Tarda are thought to originate from D-type asteroids (Hiroi et al., 2001; Marrocchi et al., 2021) considered to have formed at large heliocentric distances beyond the current orbit of Saturn, and potentially as far as the Kuiper Belt (i.e. 30--50 astronomical units = au; Levison et al., 2009). Here we report the results of a comprehensive study of the isotopic compositions of noble gases contained in Tagish Lake and Tarda to evaluate if material accreted in the outer solar system presents specific signatures. We compare our data to other CCs and discuss the origin of the variable radiogenic 129Xe excesses between and within each CC groups.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Noble gases trapped in primitive meteorites (chondrites) allow quantification of the physical processes that operated during the evolution of the protoplanetary disk (e.g., Kuga et al., 2015). Although these elements are present in different carriers contained in meteorites (including presolar SiC, diamonds, graphite; Ott, 2014), they are mainly hosted in a phase â referred to as phase Qâ whose nature is still poorly characterised (Busemann et al., 2000). Notwithstanding this uncertainty, it has been shown that phase Q dominates the heavy noble gas budget of chondrites and is closely associated with carbonaceous material that survives HF/HCl attack of bulk meteorites (Lewis et al., 1975). Thanks to its extreme sensitivity to oxidation, the xenon isotopic composition of phaseQhas been precisely determined, revealing a mass dependent isotopic fractionation relative to solar wind (SW-Xe) in favour of the heavy isotopes relative to the light ones (Wieler et al., 1991; Busemann et al., 2000; Gilmour, 2010). However, the commonly used Xe-Q isotopic composition hinges on the average of measurements of several carbonaceous chondrites (CCs) showing distinct Xe isotopic compositions between and within each group, especially for 129Xe (Busemann et al., 2000). Such 129Xe excesses result from the decay of extinct 129I (t1/2 = 16 Myr), which was producing radiogenic 129Xe* during the first â`u100 million years of the solar system (Jeffery and Reynolds, 1961). The measurement of xenon isotopes in the coma of comet 67P/Churyumov-Gerasimenko revealed extreme 129Xe enrichment relative to 132Xe and the solar composition (Marty et al., 2017). As this large monoisotopic excess would require unlikely 129I enrichment, it has been interpreted as originating from a specific nucleosynthetic process producing 129Xe that was sampled by icy bodies formed in the outer solar system (Marty et al., 2017). Interestingly, the carbon-rich primitive chondrites Tagish Lake and Tarda are thought to originate from D-type asteroids (Hiroi et al., 2001; Marrocchi et al., 2021) considered to have formed at large heliocentric distances beyond the current orbit of Saturn, and potentially as far as the Kuiper Belt (i.e. 30--50 astronomical units = au; Levison et al., 2009). Here we report the results of a comprehensive study of the isotopic compositions of noble gases contained in Tagish Lake and Tarda to evaluate if material accreted in the outer solar system presents specific signatures. We compare our data to other CCs and discuss the origin of the variable radiogenic 129Xe excesses between and within each CC groups.
63.
Yokoyama, T.; Nagashima, K.; Nakai, I.; Young, E. D.; Abe, Y.; Aléon, J.; Alexander, C. M. O’D; Amari, S.; Amelin, Y.; Bajo, K.; Bizzarro, M.; Bouvier, A.; Carlson, R. W.; Chaussidon, M.; Choi, B. G.; Dauphas, N.; Davis, A. M.; Rocco, T. Di; Fujiya, W.; Fukai, R.; Gautam, I.; Haba, M. K.; Hibiya, Y.; Hidaka, H.; Homma, H.; Hoppe, P.; Huss, G. R.; Ichida, K.; Iizuka, T.; Ireland, T. R.; Ishikawa, A.; Ito, M.; Itoh, S.; Kawasaki, N.; Kita, N. T.; Kitajima, K.; Kleine, T.; Komatani, S.; Krot, A. N.; Liu, M. C.; Masuda, Y.; McKeegan, K. D.; Morita, M.; Motomura, K.; Moynier, F.; Nguyen, A.; Nittler, L.; Onose, M.; Pack, P.; Park, C.; Piani, L.
Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites Journal Article
In: Science, 2022.
@article{Yokoyama_etal2022,
title = {Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites},
author = {T. Yokoyama and K. Nagashima and I. Nakai and E. D. Young and Y. Abe and J. Al\'{e}on and C. M. O’D Alexander and S. Amari and Y. Amelin and K. Bajo and M. Bizzarro and A. Bouvier and R. W. Carlson and M. Chaussidon and B. G. Choi and N. Dauphas and A. M. Davis and T. Di Rocco and W. Fujiya and R. Fukai and I. Gautam and M. K. Haba and Y. Hibiya and H. Hidaka and H. Homma and P. Hoppe and G. R. Huss and K. Ichida and T. Iizuka and T. R. Ireland and A. Ishikawa and M. Ito and S. Itoh and N. Kawasaki and N. T. Kita and K. Kitajima and T. Kleine and S. Komatani and A. N. Krot and M. C. Liu and Y. Masuda and K. D. McKeegan and M. Morita and K. Motomura and F. Moynier and A. Nguyen and L. Nittler and M. Onose and P. Pack and C. Park and L. Piani},
doi = {10.1126/science.abn7850},
year = {2022},
date = {2022-01-01},
urldate = {2022-01-01},
journal = {Science},
abstract = {Carbonaceous meteorites are thought to be fragments of C-type (carbonaceous) asteroids. Samples of the C-type asteroid (162173) Ryugu were retrieved by the Hayabusa2 spacecraft. We measure the mineralogy, bulk chemical and isotopic compositions of Ryugu samples. They are mainly composed of materials similar to carbonaceous chondrite meteorites, particularly the CI (Ivuna-type) group. The samples consist predominantly of minerals formed in aqueous fluid on a parent planetesimal. The primary minerals were altered by fluids at a temperature of 37 textpm 10textdegreeC, 5.2+0.7\^{a}0.8 (Stat.) +1.6\^{a}2.1 (Syst.) million years after formation of the first solids in the Solar System. After aqueous alteration, the Ryugu samples were likely never heated above textasciitilde100textdegreeC. The samples have a chemical composition that more closely resembles the Sun’s photosphere than other natural samples do.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Carbonaceous meteorites are thought to be fragments of C-type (carbonaceous) asteroids. Samples of the C-type asteroid (162173) Ryugu were retrieved by the Hayabusa2 spacecraft. We measure the mineralogy, bulk chemical and isotopic compositions of Ryugu samples. They are mainly composed of materials similar to carbonaceous chondrite meteorites, particularly the CI (Ivuna-type) group. The samples consist predominantly of minerals formed in aqueous fluid on a parent planetesimal. The primary minerals were altered by fluids at a temperature of 37 textpm 10textdegreeC, 5.2+0.7â0.8 (Stat.) +1.6â2.1 (Syst.) million years after formation of the first solids in the Solar System. After aqueous alteration, the Ryugu samples were likely never heated above textasciitilde100textdegreeC. The samples have a chemical composition that more closely resembles the Sun’s photosphere than other natural samples do.
64.
Xu, Q. H.; Wang, L.; Liu, J.; Deloule, E.; Hanski, E.; Gu, X. Y.; Chen, H.; Xia, Q. K.
Linking the Jehol Biota evolution to the Early Cretaceous volcanism during the North China craton destruction: Insights from F, Cl, S, and P Journal Article
In: Journal of Geophysical Research ?Ĭ Solid Earth, vol. 127, pp. e2022JB024388, 2022.
@article{Xu_etal2022,
title = {Linking the Jehol Biota evolution to the Early Cretaceous volcanism during the North China craton destruction: Insights from F, Cl, S, and P},
author = {Q. H. Xu and L. Wang and J. Liu and E. Deloule and E. Hanski and X. Y. Gu and H. Chen and Q. K. Xia},
doi = {10.1029/2022JB024388},
year = {2022},
date = {2022-01-01},
journal = {Journal of Geophysical Research ?\"{A}¬ Solid Earth},
volume = {127},
pages = {e2022JB024388},
abstract = {The Early Cretaceous Jehol Biota evolution has remarkable spatiotemporal correlation with the destruction of the North China craton though the coupling mechanism remains enigmatic. The craton destruction was accompanied by intense magmatic activity and the released volatiles and nutrients might have had climatic and environmental impacts on the biotic evolution. In this study, we investigated the mentioned hypothetical causal link by determining concentrations and total emissions of volatile elements (S, F, Cl) and bulk-rock P contents of volcanic rocks that were erupted during the pre-flourishing, flourishing and post-flourishing stages of the Jehol Biota. Our results show that the volcanism near the flourishing stage has lower S (1,083--2,370 ppm), Cl (1,277--5,608 ppm) and higher P2O5 contents (0.48--0.84 wt.%) than that in the non-flourishing stages with S of 1,991--3,288 ppm, Cl of 7,915--12,315 ppm and P2O5 of 0.17--0.23 wt.%.Fluorine contents in the three stages vary from 893 to 3,746 ppm. The total volatile emissions are minor in the flourishing stage (1--14 Gt S, 0.6--10 Gt Cl, 0.6--9 Gt F) but elevated in the non-flourishing stages (2--766 Gt S, 4--1,168 Gt Cl, 1--175 Gt F). Our data suggest that regional climatic and environmental impacts of volcanism in the non-flourishing stages probably hindered the species diversification. The high P flux released from lithospheric mantle-derived lavas during the peak time of craton destruction might have enhanced primaryproductivity and contributed to the flourishing of the Jehol Biota. Our study provides insights into the relationship between the biosphere and deep geodynamic processes driven by volcanism.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The Early Cretaceous Jehol Biota evolution has remarkable spatiotemporal correlation with the destruction of the North China craton though the coupling mechanism remains enigmatic. The craton destruction was accompanied by intense magmatic activity and the released volatiles and nutrients might have had climatic and environmental impacts on the biotic evolution. In this study, we investigated the mentioned hypothetical causal link by determining concentrations and total emissions of volatile elements (S, F, Cl) and bulk-rock P contents of volcanic rocks that were erupted during the pre-flourishing, flourishing and post-flourishing stages of the Jehol Biota. Our results show that the volcanism near the flourishing stage has lower S (1,083--2,370 ppm), Cl (1,277--5,608 ppm) and higher P2O5 contents (0.48--0.84 wt.%) than that in the non-flourishing stages with S of 1,991--3,288 ppm, Cl of 7,915--12,315 ppm and P2O5 of 0.17--0.23 wt.%.Fluorine contents in the three stages vary from 893 to 3,746 ppm. The total volatile emissions are minor in the flourishing stage (1--14 Gt S, 0.6--10 Gt Cl, 0.6--9 Gt F) but elevated in the non-flourishing stages (2--766 Gt S, 4--1,168 Gt Cl, 1--175 Gt F). Our data suggest that regional climatic and environmental impacts of volcanism in the non-flourishing stages probably hindered the species diversification. The high P flux released from lithospheric mantle-derived lavas during the peak time of craton destruction might have enhanced primaryproductivity and contributed to the flourishing of the Jehol Biota. Our study provides insights into the relationship between the biosphere and deep geodynamic processes driven by volcanism.
65.
Tielke, J. A.; Peslier, A. H.; Christoffersen, R.; Erickson, T. M.; Cine, II.; Jakubek, R. S.; Cintala, M. J.; Rahman, Z.; Fries, M. D.; Bouilhol, P.
Dislocation generation in experimentally shocked olivine crystals Journal Article
In: Journal of Geophysical Research (Planets), vol. 127, pp. e2021JE007042, 2022.
@article{Tielke_etal2022,
title = {Dislocation generation in experimentally shocked olivine crystals},
author = {J. A. Tielke and A. H. Peslier and R. Christoffersen and T. M. Erickson and II. Cine and R. S. Jakubek and M. J. Cintala and Z. Rahman and M. D. Fries and P. Bouilhol},
doi = {10.1029/2021JE007042},
year = {2022},
date = {2022-01-01},
journal = {Journal of Geophysical Research (Planets)},
volume = {127},
pages = {e2021JE007042},
abstract = {During shock metamorphism, crystals in planetary bodies are exposed to extreme conditions of stress, pressure, and temperature, resulting in the development of a range of shock-induced defects, including dislocations. To investigate the shock-induced development of dislocations in olivine, one of the most common minerals found in meteorites and other planetary samples, a series of shock experiments were carried out on olivine single crystals. Olivine crystals were shocked to peak reverberation pressures ranging from 21.3 to 58.7 GPa in a flat-plate accelerator. The crystals were characterized using electron backscatter diffraction (EBSD), Raman spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy, and electron microprobe. EBSD analyses reveal that geometrically necessary dislocations form on all common slip systems. Raman spectroscopy reveals that the full width at half height of characteristic peaks increases linearly as a function of shock pressure. Dislocation loops with the Burgers vector b = [001] have higher densities near fractures as revealed by TEM analyses, whereas dislocations away from fractures are more dependent on the crystal orientation relative to impact direction. The type and density of dislocations that form during shock are largely independent of the starting hydrogen content of crystals. Calculations that incorporate post-shock cooling rates of meteorites ejected from planetary surfaces, dislocation annihilation rates in olivine, and dislocation densities measured in shocked olivine suggest that shock-induced dislocations are preserved in olivine in meteorites ejected from planetary bodies and therefore give insight into the conditions of ancient impact events in the solar system.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
During shock metamorphism, crystals in planetary bodies are exposed to extreme conditions of stress, pressure, and temperature, resulting in the development of a range of shock-induced defects, including dislocations. To investigate the shock-induced development of dislocations in olivine, one of the most common minerals found in meteorites and other planetary samples, a series of shock experiments were carried out on olivine single crystals. Olivine crystals were shocked to peak reverberation pressures ranging from 21.3 to 58.7 GPa in a flat-plate accelerator. The crystals were characterized using electron backscatter diffraction (EBSD), Raman spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy, and electron microprobe. EBSD analyses reveal that geometrically necessary dislocations form on all common slip systems. Raman spectroscopy reveals that the full width at half height of characteristic peaks increases linearly as a function of shock pressure. Dislocation loops with the Burgers vector b = [001] have higher densities near fractures as revealed by TEM analyses, whereas dislocations away from fractures are more dependent on the crystal orientation relative to impact direction. The type and density of dislocations that form during shock are largely independent of the starting hydrogen content of crystals. Calculations that incorporate post-shock cooling rates of meteorites ejected from planetary surfaces, dislocation annihilation rates in olivine, and dislocation densities measured in shocked olivine suggest that shock-induced dislocations are preserved in olivine in meteorites ejected from planetary bodies and therefore give insight into the conditions of ancient impact events in the solar system.
66.
Radu, I. B.; Moine, B. N.; Bolfan-Casanova, N.; Ionov, D. A.; Devidal, J. L.; Deloule, E.; Korsakov, A. V.; Golovin, A. V.; Oleinikov, O. B.; Cottin, J. Y.
Zoisite in cratonic eclogite xenoliths - Implications for water in the upper mantle Journal Article
In: Lithos, vol. 418-419, pp. 106681, 2022.
@article{Radu_etal2022,
title = {Zoisite in cratonic eclogite xenoliths - Implications for water in the upper mantle},
author = {I. B. Radu and B. N. Moine and N. Bolfan-Casanova and D. A. Ionov and J. L. Devidal and E. Deloule and A. V. Korsakov and A. V. Golovin and O. B. Oleinikov and J. Y. Cottin},
doi = {10.1016/j.lithos.2022.106681},
year = {2022},
date = {2022-01-01},
urldate = {2022-01-01},
journal = {Lithos},
volume = {418-419},
pages = {106681},
abstract = {A significant portion of the Earth’s water is found at trace levels in nominally anhydrous rock forming minerals in the crust and mantle. Its distribution has far-reaching implications in melt-generating processes, mantle rheology and the stability of the lithosphere. We report petrographic, major and trace element, Fourier transform infrared spectroscopy and secondary ion mass spectrometry data on four eclogite xenoliths from the Obnazhennaya kimberlite, Siberia that contain hydrous minerals at upper mantle conditions. Al-rich (\>9.9 wt% Al2O3) omphacitic clinopyroxene, a major mineral of eclogites, contains crystallographically controlled exsolutions of CaO-rich (up to 23.6 wt%) garnet (coronae, lenses), garnet-zoisite (lamellae) or amphiboles (needle/blade-like exsolutions). The omphacite hosting the exsolved lamellae shows enrichment or depletion in major (Al, Si, Mg) and trace (e.g., HREE) elements compatible with garnet and zoisite, proportional to the abundance of exsolutions.We argue that zoisite likely formed concomitantly with garnet exsolution from a water- and Al-rich precursory omphacite, without any fluid addition. The compositional gradients are consistent with diffusion-controlled partitioning in a closed system, and their preservation indicates the exsolution likely took place shortly prior to eclogite entrapment by the kimberlite. Large, non-exsolved, omphacite grains contain minimum textasciitilde870--1500ppm wt. H2O (determined as OH). We infer that intertwined lamellae of hydrous garnet (600--960 ppm wt. H2O)and minor (\<1%) zoisite (2 wt% H2O) formed at mantle conditions due to progressive exsolution, withoutexternal fluids. Recalculated whole rock water contents range from textasciitilde320 to 970 ppm wt. H2O. These estimatesexceed by far those for the surrounding peridotitic mantle and suggest that, although a minor component,eclogites may locally be an important water reservoir in the cratonic mantle.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A significant portion of the Earth’s water is found at trace levels in nominally anhydrous rock forming minerals in the crust and mantle. Its distribution has far-reaching implications in melt-generating processes, mantle rheology and the stability of the lithosphere. We report petrographic, major and trace element, Fourier transform infrared spectroscopy and secondary ion mass spectrometry data on four eclogite xenoliths from the Obnazhennaya kimberlite, Siberia that contain hydrous minerals at upper mantle conditions. Al-rich (>9.9 wt% Al2O3) omphacitic clinopyroxene, a major mineral of eclogites, contains crystallographically controlled exsolutions of CaO-rich (up to 23.6 wt%) garnet (coronae, lenses), garnet-zoisite (lamellae) or amphiboles (needle/blade-like exsolutions). The omphacite hosting the exsolved lamellae shows enrichment or depletion in major (Al, Si, Mg) and trace (e.g., HREE) elements compatible with garnet and zoisite, proportional to the abundance of exsolutions.We argue that zoisite likely formed concomitantly with garnet exsolution from a water- and Al-rich precursory omphacite, without any fluid addition. The compositional gradients are consistent with diffusion-controlled partitioning in a closed system, and their preservation indicates the exsolution likely took place shortly prior to eclogite entrapment by the kimberlite. Large, non-exsolved, omphacite grains contain minimum textasciitilde870--1500ppm wt. H2O (determined as OH). We infer that intertwined lamellae of hydrous garnet (600--960 ppm wt. H2O)and minor (<1%) zoisite (2 wt% H2O) formed at mantle conditions due to progressive exsolution, withoutexternal fluids. Recalculated whole rock water contents range from textasciitilde320 to 970 ppm wt. H2O. These estimatesexceed by far those for the surrounding peridotitic mantle and suggest that, although a minor component,eclogites may locally be an important water reservoir in the cratonic mantle.
67.
Pignatelli, I.; Giuliani, G.; Morlot, C.; Pardieu, V.
The ‘Star of David’ pattern and presence of macrosteps on ruby and sapphire crystals from Aappaluttoq, Greenland Journal Article
In: Journal of Gemmology, vol. 38, no. 4, pp. 364–375, 2022.
@article{Pignatelli_etal2022,
title = {The ‘Star of David’ pattern and presence of macrosteps on ruby and sapphire crystals from Aappaluttoq, Greenland},
author = {I. Pignatelli and G. Giuliani and C. Morlot and V. Pardieu},
doi = {10.15506/JoG.2022.38.4.364},
year = {2022},
date = {2022-01-01},
journal = {Journal of Gemmology},
volume = {38},
number = {4},
pages = {364--375},
abstract = {A ‘Star of David’ appearance is rarely exhibited on gem corundum crystals due totriangular step patterns in opposing orientations on each pinacoidal face. Such samples were recently found at the Aappaluttoq mine in Greenland, and are characterised by eye-visible triangular macrosteps with micrometre- to millimetre-size edges, an uncommon feature on natural corundum crystals. The edge height, as well as the presence of wide terraces and trench-like defects on the crystals, suggest that the macrosteps result from step bunching and faceting1 processes. The macrosteps likely formed under high-temperature conditions and intense fluid-rock interactions, in a growth medium where impurities and direction of fluid flow played an important role in the step formation. Large macrosteps are also found on corundum crystals from other deposits of both magmatic and metamorphic origin.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A ‘Star of David’ appearance is rarely exhibited on gem corundum crystals due totriangular step patterns in opposing orientations on each pinacoidal face. Such samples were recently found at the Aappaluttoq mine in Greenland, and are characterised by eye-visible triangular macrosteps with micrometre- to millimetre-size edges, an uncommon feature on natural corundum crystals. The edge height, as well as the presence of wide terraces and trench-like defects on the crystals, suggest that the macrosteps result from step bunching and faceting1 processes. The macrosteps likely formed under high-temperature conditions and intense fluid-rock interactions, in a growth medium where impurities and direction of fluid flow played an important role in the step formation. Large macrosteps are also found on corundum crystals from other deposits of both magmatic and metamorphic origin.
68.
Ou, Q.; Daout, S.; Weiss, J. R.; Shen, L.; Lazecky, M.; Wright, T. J.; Parsons, B. E.
Large-scale interseismic strain mapping of the NE Tibetan Plateau from sentinel-1 interferometry Journal Article
In: Journal of Geophysical Research ?Ĭ Solid Earth, vol. 127, pp. e2022JB024176, 2022.
@article{Ou_etal2022,
title = {Large-scale interseismic strain mapping of the NE Tibetan Plateau from sentinel-1 interferometry},
author = {Q. Ou and S. Daout and J. R. Weiss and L. Shen and M. Lazecky and T. J. Wright and B. E. Parsons},
doi = {10.1029/2022JB024176},
year = {2022},
date = {2022-01-01},
journal = {Journal of Geophysical Research ?\"{A}¬ Solid Earth},
volume = {127},
pages = {e2022JB024176},
abstract = {The launches of the Sentinel-1 synthetic aperture radar satellites in 2014 and 2016 started a new era of high-resolution velocity and strain rate mapping for the continents. However, multiple challenges exist in tying independently processed velocity data sets to a common reference frame and producing high-resolution strain rate fields. We analyze Sentinel-1 data acquired between 2014 and 2019 over the northeast Tibetan Plateau, and develop new methods to derive east and vertical velocities with \^{a}`u100 m resolution and \^{a}`u1 mm/yr accuracy across an area of 440,000 km2. By implementing a new method of combining horizontal gradients of filtered east and interpolated north velocities, we derive the first \^{a}`u1 km resolution strain rate field for this tectonically active region. The strain rate fields show concentrated shear strain along the Haiyuan and East Kunlun Faults, and local contractional strain on fault junctions, within the Qilianshan thrusts, and around the Longyangxia Reservoir. The Laohushan-Jingtai creeping section of the Haiyuan Fault is highlighted in our data set by extremely rapid strain rates. Strain across unknown portions of the Haiyuan Fault system, including shear on the eastern extension of the Dabanshan Fault and contraction at the western flank of the Quwushan, highlight unmapped tectonic structures. In addition to the uplift across most of the lowlands, the vertical velocities also contain climatic, hydrological or anthropogenic-related deformation signals. We demonstrate the enhanced view of large-scale active tectonic processes provided by high-resolution velocities and strain rates derived from Sentinel-1 data and highlight associated wide-ranging research applications.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The launches of the Sentinel-1 synthetic aperture radar satellites in 2014 and 2016 started a new era of high-resolution velocity and strain rate mapping for the continents. However, multiple challenges exist in tying independently processed velocity data sets to a common reference frame and producing high-resolution strain rate fields. We analyze Sentinel-1 data acquired between 2014 and 2019 over the northeast Tibetan Plateau, and develop new methods to derive east and vertical velocities with â`u100 m resolution and â`u1 mm/yr accuracy across an area of 440,000 km2. By implementing a new method of combining horizontal gradients of filtered east and interpolated north velocities, we derive the first â`u1 km resolution strain rate field for this tectonically active region. The strain rate fields show concentrated shear strain along the Haiyuan and East Kunlun Faults, and local contractional strain on fault junctions, within the Qilianshan thrusts, and around the Longyangxia Reservoir. The Laohushan-Jingtai creeping section of the Haiyuan Fault is highlighted in our data set by extremely rapid strain rates. Strain across unknown portions of the Haiyuan Fault system, including shear on the eastern extension of the Dabanshan Fault and contraction at the western flank of the Quwushan, highlight unmapped tectonic structures. In addition to the uplift across most of the lowlands, the vertical velocities also contain climatic, hydrological or anthropogenic-related deformation signals. We demonstrate the enhanced view of large-scale active tectonic processes provided by high-resolution velocities and strain rates derived from Sentinel-1 data and highlight associated wide-ranging research applications.
69.
Marrocchi, Y.; Piralla, M.; Regnault, M.; Batanova, V.; Villeneuve, J.; Jacquet, E.
Isotopic evidence for two chondrule generations in CR chondrites and their relationships to other carbonaceous chondrites Journal Article
In: Earth and Planetary Science Letters, vol. 593, pp. 117683, 2022.
@article{Marrocchi_etal2022,
title = {Isotopic evidence for two chondrule generations in CR chondrites and their relationships to other carbonaceous chondrites},
author = {Y. Marrocchi and M. Piralla and M. Regnault and V. Batanova and J. Villeneuve and E. Jacquet},
doi = {10.1016/j.epsl.2022.117683},
year = {2022},
date = {2022-01-01},
journal = {Earth and Planetary Science Letters},
volume = {593},
pages = {117683},
abstract = {Among primitive meteorites, CR chondrites have peculiar isotopic compositions, the origin of which is uncertain and may have involved contributions from primordial molecular cloud material or the chondrites’ formation and agglomeration late during the evolution of the protoplanetary disk. Here, we report a comprehensive textural and isotopic characterization of type I CR chondrules and provide new insights on their formation conditions. We find that two chondrule populations characterized bydifferent sizes and oxygen isotopic compositions co-exist in CR chondrites. The typically larger, 16O-poor (17O \> -4) chondrules (type I-CR chondrules) appear to have formed late out of a CR reservoir already populated by typically smaller, 16O-rich (17O \< -4) chondrules (type I-CO chondrules). Before formation of type I-CR chondrules, the CR reservoir was likely dominated by CI-like dust, in line with the proximity of CR with CI chondrites for many isotopic ratios. The CR reservoir thus may have largely belonged to the continuum shown by other carbonaceous chondrites, although some isotopic ratios maintain some originality and suggest isotopic variation of CI-like dust in the outer disk. Combined with literature data,our data (i) demonstrates that recycling processes are responsible for the singular compositions of CR chondrites and their chondrules for isotopic systems with drastically different geochemical behaviors (O, Cr, Te) and (ii) support the homogeneous distribution of 26Al throughout the protoplanetary disk.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Among primitive meteorites, CR chondrites have peculiar isotopic compositions, the origin of which is uncertain and may have involved contributions from primordial molecular cloud material or the chondrites’ formation and agglomeration late during the evolution of the protoplanetary disk. Here, we report a comprehensive textural and isotopic characterization of type I CR chondrules and provide new insights on their formation conditions. We find that two chondrule populations characterized bydifferent sizes and oxygen isotopic compositions co-exist in CR chondrites. The typically larger, 16O-poor (17O > -4) chondrules (type I-CR chondrules) appear to have formed late out of a CR reservoir already populated by typically smaller, 16O-rich (17O < -4) chondrules (type I-CO chondrules). Before formation of type I-CR chondrules, the CR reservoir was likely dominated by CI-like dust, in line with the proximity of CR with CI chondrites for many isotopic ratios. The CR reservoir thus may have largely belonged to the continuum shown by other carbonaceous chondrites, although some isotopic ratios maintain some originality and suggest isotopic variation of CI-like dust in the outer disk. Combined with literature data,our data (i) demonstrates that recycling processes are responsible for the singular compositions of CR chondrites and their chondrules for isotopic systems with drastically different geochemical behaviors (O, Cr, Te) and (ii) support the homogeneous distribution of 26Al throughout the protoplanetary disk.
70.
Lorenzon, S.; Novella, D.; Nimis, P.; Jacobsen, S. D.; Thomassot, E.; Pamato, M. G.; Prosperi, L.; Lorenzetti, A.; Alvaro, M.; Brenker, F.; Salvadego, F.; Nestola, F.
Ringwoodite and zirconia inclusions indicate downward travel of super-deep diamonds Journal Article
In: Geology, 2022.
@article{Lorenzon_etal2022,
title = {Ringwoodite and zirconia inclusions indicate downward travel of super-deep diamonds},
author = {S. Lorenzon and D. Novella and P. Nimis and S. D. Jacobsen and E. Thomassot and M. G. Pamato and L. Prosperi and A. Lorenzetti and M. Alvaro and F. Brenker and F. Salvadego and F. Nestola},
doi = {10.1130/G50111.1},
year = {2022},
date = {2022-01-01},
journal = {Geology},
abstract = {Natural diamonds and their inclusions provide unique glimpses of mantle processes from as deep as \^{a}`u800 km and dating back to 3.5 G.y. Once formed, diamonds are commonly interpreted to travel upward, either slowly within mantle upwellings or rapidly within explosive, carbonate-rich magmas erupting at the surface. Although global tectonics induce subduction of material from shallow depths into the deep mantle, mineralogical evidence for downward movements of diamonds has never been reported. We report the finding of an unusual composite inclusion consisting of ringwoodite (the second finding to date), tetragonal zirconia, and coesite within an alluvial super-deep diamond from the Central African Republic. We interpret zirconia + coesite and ringwoodite as prograde transformation products after zircon or reidite (ZrSiO4) and olivine or wadsleyite, respectively. This inclusion assemblage can be explained if the diamond traveled downward after entrapping olivine/wadsleyite + zircon/reidite, dragged down by a subducting slab, before being delivered to the surface. This indicates that the commonly assumed view that diamonds form at, and capture material from, a specific mantle level and then travel upward is probably too simplistic.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Natural diamonds and their inclusions provide unique glimpses of mantle processes from as deep as â`u800 km and dating back to 3.5 G.y. Once formed, diamonds are commonly interpreted to travel upward, either slowly within mantle upwellings or rapidly within explosive, carbonate-rich magmas erupting at the surface. Although global tectonics induce subduction of material from shallow depths into the deep mantle, mineralogical evidence for downward movements of diamonds has never been reported. We report the finding of an unusual composite inclusion consisting of ringwoodite (the second finding to date), tetragonal zirconia, and coesite within an alluvial super-deep diamond from the Central African Republic. We interpret zirconia + coesite and ringwoodite as prograde transformation products after zircon or reidite (ZrSiO4) and olivine or wadsleyite, respectively. This inclusion assemblage can be explained if the diamond traveled downward after entrapping olivine/wadsleyite + zircon/reidite, dragged down by a subducting slab, before being delivered to the surface. This indicates that the commonly assumed view that diamonds form at, and capture material from, a specific mantle level and then travel upward is probably too simplistic.
71.
Liu, J.; Tao, C. H.; Zhou, J. P.; Shimizu, K.; Li, W.; Liang, J.; Liao, S.; Kuritani, T.; Deloule, E.; Ushikubo, T.; Nakagawa, T.; Yang, W. F.; Zhang, G.; Liu, Y. L.; Zhu, C. W.; Sun, H.; Zhou, J.
Water enrichment in the mid-ocean ridge by recycling of mantle wedge residue Journal Article
In: Earth and Planetary Science Letters, vol. 584, pp. 116550, 2022.
@article{Liu_etal2022,
title = {Water enrichment in the mid-ocean ridge by recycling of mantle wedge residue},
author = {J. Liu and C. H. Tao and J. P. Zhou and K. Shimizu and W. Li and J. Liang and S. Liao and T. Kuritani and E. Deloule and T. Ushikubo and T. Nakagawa and W. F. Yang and G. Zhang and Y. L. Liu and C. W. Zhu and H. Sun and J. Zhou},
doi = {10.1016/j.epsl.2022.117455},
year = {2022},
date = {2022-01-01},
journal = {Earth and Planetary Science Letters},
volume = {584},
pages = {116550},
abstract = {Trace amounts of water in the sub-oceanic mantle play crucial role in the vigor of mantle convection and the production of oceanic crust, and other many geodynamic processes. Consequently, the cycling of H2O between the mantle and the exosphere in the mantle is one of the critical processes governing Earth’s geodynamical and geochemical evolution. While the deep cycling of altered oceanic lithosphere was considered as the main way to replenish the water in oceanic upper mantle, the significance of the arc mantle wedge after the genesis of arc magmatism dragged down by the subducting slab concomitantly has been not well constrained. Here, we report that fresh depleted basaltic glasses from the ultraslow-spreading Southwestern Indian Ridge (SWIR), located far from any recent subduction zones, show unusually high H2O/Ce ratios (\>600), water contents and heavy hydrogen isotopic compositions. These results could be best explained by recycling of water through melting of a residual hydrous mantle wedge after early melt extraction. Considering that such mantle wedges residue dragged down to the deeper mantle could occupy a volume one order of magnitude larger than that of the subducted lithosphere in the earth history, we suggest that the potential role of such shallow recycling should be considered in studies of global water recycling and the origin of water in the upper asthenosphere.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Trace amounts of water in the sub-oceanic mantle play crucial role in the vigor of mantle convection and the production of oceanic crust, and other many geodynamic processes. Consequently, the cycling of H2O between the mantle and the exosphere in the mantle is one of the critical processes governing Earth’s geodynamical and geochemical evolution. While the deep cycling of altered oceanic lithosphere was considered as the main way to replenish the water in oceanic upper mantle, the significance of the arc mantle wedge after the genesis of arc magmatism dragged down by the subducting slab concomitantly has been not well constrained. Here, we report that fresh depleted basaltic glasses from the ultraslow-spreading Southwestern Indian Ridge (SWIR), located far from any recent subduction zones, show unusually high H2O/Ce ratios (>600), water contents and heavy hydrogen isotopic compositions. These results could be best explained by recycling of water through melting of a residual hydrous mantle wedge after early melt extraction. Considering that such mantle wedges residue dragged down to the deeper mantle could occupy a volume one order of magnitude larger than that of the subducted lithosphere in the earth history, we suggest that the potential role of such shallow recycling should be considered in studies of global water recycling and the origin of water in the upper asthenosphere.
72.
Ito, G.; Flahaut, J.; Gonzalez-Maurel, O.; Godoy, B.; Payet, V.; Barthez, M.
Remote sensing survey of Altiplano-Puna volcanic complex rocks and minerals for planetary analog use Journal Article
In: Remote Sensing, vol. 14, no. 9, pp. 2081, 2022.
@article{Ito_etal2022,
title = {Remote sensing survey of Altiplano-Puna volcanic complex rocks and minerals for planetary analog use},
author = {G. Ito and J. Flahaut and O. Gonzalez-Maurel and B. Godoy and V. Payet and M. Barthez},
doi = {10.3390/rs14092081},
year = {2022},
date = {2022-01-01},
journal = {Remote Sensing},
volume = {14},
number = {9},
pages = {2081},
abstract = {The Altiplano-Puna Volcanic Complex (APVC) of the Central Andes is an arid region with extensive volcanism, possessing various geological features comparable to those of other solar system objects. The unique features of the APVC, e.g., hydrothermal fields and evaporite salars, have been used as planetary analogs before, but the complexity of the APVC presents a wealth of opportunities for more analog studies that have not been exploited previously. Motivated by the potential of using the APVC as an analog of the volcanic terrains of solar system objects, we mapped the mineralogy and silica content of the APVC up to 100,000 km2 in northern Chile based on a combination of remote sensing data resembling those of the Moon and Mars. The band ratio indices of Landsat 8 Operational Land Imager multispectral images and mineral classifications based on spectral hourglass approach using Earth Observing-1 Hyperion hyperspectral images (both in the visible to shortwave infrared wavelengths) were used to map iron-bearing and alteration minerals. We also used Hyperion imagery to detect feldspar spectral signatures and demonstrated that feldspar minerals can be detected on non-anorthosites, which may influence interpretations of feldspar spectral signatures on Mars. From the Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Emissivity Dataset, we derived the silica percentage of non-evaporite rocks within errors of approximately 2--3 wt.% SiO2 for those in the 60--70 wt.% range (about 8 wt.% errors for the 50--60 wt.% range). Based on an integrated assessment of the three datasets, we highlighted three regions of particular interest worthy of further field investigation. We also evaluated the benefits and limitations of all three remote sensing methods for mapping key minerals and capturing rock diversity, based on available samples and existing geological maps.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The Altiplano-Puna Volcanic Complex (APVC) of the Central Andes is an arid region with extensive volcanism, possessing various geological features comparable to those of other solar system objects. The unique features of the APVC, e.g., hydrothermal fields and evaporite salars, have been used as planetary analogs before, but the complexity of the APVC presents a wealth of opportunities for more analog studies that have not been exploited previously. Motivated by the potential of using the APVC as an analog of the volcanic terrains of solar system objects, we mapped the mineralogy and silica content of the APVC up to 100,000 km2 in northern Chile based on a combination of remote sensing data resembling those of the Moon and Mars. The band ratio indices of Landsat 8 Operational Land Imager multispectral images and mineral classifications based on spectral hourglass approach using Earth Observing-1 Hyperion hyperspectral images (both in the visible to shortwave infrared wavelengths) were used to map iron-bearing and alteration minerals. We also used Hyperion imagery to detect feldspar spectral signatures and demonstrated that feldspar minerals can be detected on non-anorthosites, which may influence interpretations of feldspar spectral signatures on Mars. From the Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Emissivity Dataset, we derived the silica percentage of non-evaporite rocks within errors of approximately 2--3 wt.% SiO2 for those in the 60--70 wt.% range (about 8 wt.% errors for the 50--60 wt.% range). Based on an integrated assessment of the three datasets, we highlighted three regions of particular interest worthy of further field investigation. We also evaluated the benefits and limitations of all three remote sensing methods for mapping key minerals and capturing rock diversity, based on available samples and existing geological maps.
73.
Girault, F.; Viveiros, F.; Silva, C.; Thapa, S.; Pacheco, J. E.; Adhikari, L. B.; Bhattarai, M.; Koirala, B. P.; Agrinier, P.; France-Lanord, C.; Zanon, V.; Vandemeulebrouck, J.; Byrdina, S.; Perrier, F.
Radon signature of CO2 flux constrains the depth of degassing: Furnas volcano (Azores, Portugal) versus SyabruâBensi (Nepal Himalayas) Journal Article
In: Scientific Reports, vol. 12, pp. 10837, 2022.
@article{Girault_etal2022,
title = {Radon signature of CO2 flux constrains the depth of degassing: Furnas volcano (Azores, Portugal) versus Syabru\^{a}Bensi (Nepal Himalayas)},
author = {F. Girault and F. Viveiros and C. Silva and S. Thapa and J. E. Pacheco and L. B. Adhikari and M. Bhattarai and B. P. Koirala and P. Agrinier and C. France-Lanord and V. Zanon and J. Vandemeulebrouck and S. Byrdina and F. Perrier},
doi = {10.1038/s41598-022-14653-5},
year = {2022},
date = {2022-01-01},
journal = {Scientific Reports},
volume = {12},
pages = {10837},
abstract = {Substantial terrestrial gas emissions, such as carbon dioxide (CO2), are associated with active volcanoes and hydrothermal systems. However, while fundamental for the prediction of future activity, it remains difficult so far to determine the depth of the gas sources. Here we show how the combined measurement of CO2 and radon-222 fluxes at the surface constrains the depth of degassing at two hydrothermal systems in geodynamically active contexts: Furnas Lake Fumarolic Field (FLFF, Azores, Portugal) with mantellic and volcano-magmatic CO2, and Syabru-Bensi Hydrothermal System (SBHS, Central Nepal) with metamorphic CO2. At both sites, radon fluxes reach exceptionally high values (\> 10 Bq m\^{a}2 s\^{a}1) systematically associated with large CO2 fluxes (\> 10 kg m\^{a}2 day\^{a}1). The significant radon\^{a}CO2 fluxes correlation is well reproduced by an advective--diffusive model of radon transport, constrained by a thorough characterisation of radon sources. Estimates of degassing depth, 2580 textpm 180 m at FLFF and 380 textpm 20 m at SBHS, are compatible with known structures of both systems. Our approach demonstrates that radon\^{a}CO2 coupling is a powerful tool to ascertain gas sources and monitor active sites. The exceptionally high radon discharge from FLFF during quiescence (\^{a} 9 GBq day\^{a}1) suggests significant radon output from volcanoes worldwide, potentially affecting atmosphere ionisation and climate.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Substantial terrestrial gas emissions, such as carbon dioxide (CO2), are associated with active volcanoes and hydrothermal systems. However, while fundamental for the prediction of future activity, it remains difficult so far to determine the depth of the gas sources. Here we show how the combined measurement of CO2 and radon-222 fluxes at the surface constrains the depth of degassing at two hydrothermal systems in geodynamically active contexts: Furnas Lake Fumarolic Field (FLFF, Azores, Portugal) with mantellic and volcano-magmatic CO2, and Syabru-Bensi Hydrothermal System (SBHS, Central Nepal) with metamorphic CO2. At both sites, radon fluxes reach exceptionally high values (> 10 Bq mâ2 sâ1) systematically associated with large CO2 fluxes (> 10 kg mâ2 dayâ1). The significant radonâCO2 fluxes correlation is well reproduced by an advective--diffusive model of radon transport, constrained by a thorough characterisation of radon sources. Estimates of degassing depth, 2580 textpm 180 m at FLFF and 380 textpm 20 m at SBHS, are compatible with known structures of both systems. Our approach demonstrates that radonâCO2 coupling is a powerful tool to ascertain gas sources and monitor active sites. The exceptionally high radon discharge from FLFF during quiescence (â 9 GBq dayâ1) suggests significant radon output from volcanoes worldwide, potentially affecting atmosphere ionisation and climate.
74.
Faure, F.; Auxerre, M.; Casola, V.
Slow cooling during crystallisation of barred olivine chondrules Journal Article
In: Earth and Planetary Science Letters, vol. 593, pp. 117649, 2022.
@article{Faure_etal2022,
title = {Slow cooling during crystallisation of barred olivine chondrules},
author = {F. Faure and M. Auxerre and V. Casola},
doi = {10.1016/j.epsl.2022.117649},
year = {2022},
date = {2022-01-01},
journal = {Earth and Planetary Science Letters},
volume = {593},
pages = {117649},
abstract = {Barred olivine (BO) chondrules are small ferromagnesian silicate igneous droplets with unique dendritic textures that are considered to have formed in the early solar system during one or more brief high-temperature episodes, followed by rapid cooling in a gas. Rapid cooling rates of 100--7200 \^{a}¦C/h during chondrule formation have been proposed based on experiments attempting to reproduce BO crystal textures. However, the BO texture has never truly been reproduced under such rapid cooling conditions. Here, we experimentally show that true BO textures can be produced either after rapid cooling (\>50 \^{a}¦C/h) following by reheating step or by cooling rates slower than 10 \^{a}¦C/h. Regardless of the thermal history considered, the chemical compositions of glass inclusions trapped within olivines of BO chondrules imply a final slow cooling rate one to two orders of magnitude below previous estimates. Such slow cooling rates are consistent with those estimated for plagioclase-bearing porphyritic chondrules and magmatic type-B Ca-Al-rich inclusions, suggesting that slow cooling rates are common to all similar chondritic objects.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Barred olivine (BO) chondrules are small ferromagnesian silicate igneous droplets with unique dendritic textures that are considered to have formed in the early solar system during one or more brief high-temperature episodes, followed by rapid cooling in a gas. Rapid cooling rates of 100--7200 â¦C/h during chondrule formation have been proposed based on experiments attempting to reproduce BO crystal textures. However, the BO texture has never truly been reproduced under such rapid cooling conditions. Here, we experimentally show that true BO textures can be produced either after rapid cooling (>50 â¦C/h) following by reheating step or by cooling rates slower than 10 â¦C/h. Regardless of the thermal history considered, the chemical compositions of glass inclusions trapped within olivines of BO chondrules imply a final slow cooling rate one to two orders of magnitude below previous estimates. Such slow cooling rates are consistent with those estimated for plagioclase-bearing porphyritic chondrules and magmatic type-B Ca-Al-rich inclusions, suggesting that slow cooling rates are common to all similar chondritic objects.
75.
Dodds, N.; Daout, S.; Walker, R. T.; Begenjev, G.; Bezmenov, Y.; Mirzin, R.; Parsons, B.
Interseismic deformation and strain-partitioning along the Main Köpetdag Fault, Turkmenistan, with Sentinel-1 InSAR time-series Journal Article
In: Geophysical Journal International, vol. 230, no. 3, pp. 1612–1629, 2022.
@article{Dodds_etal2022,
title = {Interseismic deformation and strain-partitioning along the Main K\"{o}petdag Fault, Turkmenistan, with Sentinel-1 InSAR time-series},
author = {N. Dodds and S. Daout and R. T. Walker and G. Begenjev and Y. Bezmenov and R. Mirzin and B. Parsons},
year = {2022},
date = {2022-01-01},
journal = {Geophysical Journal International},
volume = {230},
number = {3},
pages = {1612--1629},
abstract = {The Main K\"{o}petdag Fault (MKDF) is a predominantly right-lateral strike-slip fault that dissects the northern edge of the K\"{o}petdag mountains of Turkmenistan and Iran. The fault represents the northernmost expression of deformation from the Arabia--Eurasia collision to the east of the Caspian Sea, and plays an important role facilitating the motion of the South Caspian Basin (SCB). Despite the kinematic significance of the MKDF, previous geodetic measurements of the slip-rate across the fault have been highly variable, with a recent geological slip-rate supporting evidence for rapid motion across the fault. To resolve this ambiguity, we derive Sentinel-1 InSAR time-series in both the ascending and descending LOS (line-of-sight) to measure interseismic motion across the MKDF. This implements a processing strategy for the correction and performance analysis of tropospheric models from GACOS (Generic Atmospheric Correction Online Service), which suggests a 25--40 per cent underestimation in the amplitude of the tropospheric path delay in this region. Modelling the rate of fault-parallel motion across the MKDF and combining this with a geological slip-rate constrains 9 textpm 2 mmthinspaceyr--1 right-lateral motion, along with a shallow locking depth of \^{a}6 km. The LOS time-series resolves path delays of greater than 1 mmthinspaceyr--1 in both LOS geometries to the north of the MKDF, aligned with mapped frontal thrust scarps to the north of the MKDF. Modelling this as uplift from deformation across these frontal thrusts estimates 4 textpm 2 mmthinspaceyr--1 of shortening across the fault system. This implies that convergence measured with GNSS within the East Caspian Lowlands is partitioned across frontal thrusts to the north of the MKDF. Revising an Iran--Eurasia--SCB velocity triangle suggests that motion along the conjugate MKDF and Shahroud fault zones is representative of the motion of the SCB, which is moving at 10 textpm 2 mmthinspaceyr--1 in a direction of 330textdegree textpm 10textdegree relative to Eurasia.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The Main Köpetdag Fault (MKDF) is a predominantly right-lateral strike-slip fault that dissects the northern edge of the Köpetdag mountains of Turkmenistan and Iran. The fault represents the northernmost expression of deformation from the Arabia--Eurasia collision to the east of the Caspian Sea, and plays an important role facilitating the motion of the South Caspian Basin (SCB). Despite the kinematic significance of the MKDF, previous geodetic measurements of the slip-rate across the fault have been highly variable, with a recent geological slip-rate supporting evidence for rapid motion across the fault. To resolve this ambiguity, we derive Sentinel-1 InSAR time-series in both the ascending and descending LOS (line-of-sight) to measure interseismic motion across the MKDF. This implements a processing strategy for the correction and performance analysis of tropospheric models from GACOS (Generic Atmospheric Correction Online Service), which suggests a 25--40 per cent underestimation in the amplitude of the tropospheric path delay in this region. Modelling the rate of fault-parallel motion across the MKDF and combining this with a geological slip-rate constrains 9 textpm 2 mmthinspaceyr--1 right-lateral motion, along with a shallow locking depth of â6 km. The LOS time-series resolves path delays of greater than 1 mmthinspaceyr--1 in both LOS geometries to the north of the MKDF, aligned with mapped frontal thrust scarps to the north of the MKDF. Modelling this as uplift from deformation across these frontal thrusts estimates 4 textpm 2 mmthinspaceyr--1 of shortening across the fault system. This implies that convergence measured with GNSS within the East Caspian Lowlands is partitioned across frontal thrusts to the north of the MKDF. Revising an Iran--Eurasia--SCB velocity triangle suggests that motion along the conjugate MKDF and Shahroud fault zones is representative of the motion of the SCB, which is moving at 10 textpm 2 mmthinspaceyr--1 in a direction of 330textdegree textpm 10textdegree relative to Eurasia.
76.
Dasari, S.; Paris, G.; Charreau, J.; Savarino, J.
Sulfur-isotope anomalies recorded in Antarctic ice cores as a potential proxy for tracing past ozone layer depletion events Journal Article
In: PNAS Nexus, vol. 1, pp. 1–9, 2022.
@article{Dasari_etal2022,
title = {Sulfur-isotope anomalies recorded in Antarctic ice cores as a potential proxy for tracing past ozone layer depletion events},
author = {S. Dasari and G. Paris and J. Charreau and J. Savarino},
doi = {10.1093/pnasnexus/pgac170},
year = {2022},
date = {2022-01-01},
journal = {PNAS Nexus},
volume = {1},
pages = {1--9},
abstract = {Changes in the cosmic-ray background of the Earth can impact the ozone layer. High-energy cosmic events [e.g. supernova (SN)] or rapid changes in the Earth’s magnetic field [e.g. geomagnetic Excursion (GE)] can lead to a cascade of cosmic rays. Ensuing chemical reactions can then cause thinning/destruction of the ozone layer---leading to enhanced penetration of harmful ultraviolet (UV) radiation toward the Earth’s surface. However, observational evidence for such UV ‘‘windows’’ is still lacking. Here,we conduct a pilot study and investigate this notion during two well-known events: the multiple SN event (≈10 kBP) and the Laschamp GE event (≈41 kBP).We hypothesize that ice-core-$Delta$33S records---originally used as volcanic fingerprints---can reveal UV-induced background-troposphericphotochemical imprints during such events. Indeed, we find nonvolcanic S-isotopic anomalies ($Delta$33S ≠ 0texttenthousand) in background Antarctic ice-core sulfate during GE/SN periods, thereby confirming our hypothesis. This suggests that ice-core-$Delta$33S records can serve as a proxy for past ozone-layer-depletion events},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Changes in the cosmic-ray background of the Earth can impact the ozone layer. High-energy cosmic events [e.g. supernova (SN)] or rapid changes in the Earth’s magnetic field [e.g. geomagnetic Excursion (GE)] can lead to a cascade of cosmic rays. Ensuing chemical reactions can then cause thinning/destruction of the ozone layer---leading to enhanced penetration of harmful ultraviolet (UV) radiation toward the Earth’s surface. However, observational evidence for such UV ‘‘windows’’ is still lacking. Here,we conduct a pilot study and investigate this notion during two well-known events: the multiple SN event (≈10 kBP) and the Laschamp GE event (≈41 kBP).We hypothesize that ice-core-$Delta$33S records---originally used as volcanic fingerprints---can reveal UV-induced background-troposphericphotochemical imprints during such events. Indeed, we find nonvolcanic S-isotopic anomalies ($Delta$33S ≠ 0texttenthousand) in background Antarctic ice-core sulfate during GE/SN periods, thereby confirming our hypothesis. This suggests that ice-core-$Delta$33S records can serve as a proxy for past ozone-layer-depletion events
77.
Condamine, P.; Couzinié, S.; Fabbrizio, A.; Devidal, J. L.; Médard, E.
Trace element partitioning during incipient melting of phlogopite-peridotite in the spinel and garnet stability fields Journal Article
In: Geochimica et Cosmochimica Acta, vol. 327, pp. 53–78, 2022.
@article{Condamine_etal2022,
title = {Trace element partitioning during incipient melting of phlogopite-peridotite in the spinel and garnet stability fields},
author = {P. Condamine and S. Couzini\'{e} and A. Fabbrizio and J. L. Devidal and E. M\'{e}dard},
doi = {10.1016/j.gca.2022.04.011},
year = {2022},
date = {2022-01-01},
journal = {Geochimica et Cosmochimica Acta},
volume = {327},
pages = {53--78},
abstract = {Potassium-rich magmatism represents subordinate magma volumes worldwide but has been observed in many geodynamic settings. Most potassic magmas are thought to derive from very-low degrees of melting of metasomatized mantle lithologies.We performed piston-cylinder experiments to determine trace element partition coefficients between incipient potassic silicate melts and phlogopite textpm pargasite peridotite in the spinel (1 GPa) and garnet stability fields (3 GPa). Most of the rare Earth elements (REEs) are compatible in pargasite but incompatible in phlogopite. Although garnet remains the mineral phase most efficiently fractionating heavy from light REEs (Dgrt=melt Yb =Dgrt=melt La \> 750), orthopyroxene can also significantly fractionate REEs, e.g., achieving Dopx=melt Yb =Dopx=melt La \> 100 at 3 GPa. Mineral-liquid partition coefficients vary by about one order of magnitude between incipient melts derived from the spinel and garnet stability fields. We thus show that trace element partitioning at the onset of melting is controlled more by pressure (through melt composition) than by the extent of melting. With increasing pressure, Rb and Ba exhibit different behaviors in phlogopite, with Dphl=melt Ba \> Dphl=melt Rb at 1 GPa and the opposite at 3 GPa. At 1 GPa, a decrease of melt polymerization (lower NBO/T) with increasing melt fraction translates into a significant decrease of most phlogopite partition coefficients. Finally, we show that resolvable inter-element fractionations do occur when phlogopite- (and pargasite)-bearing peridotite are melted, indicating that trace element ratios are not always faithfully representative of that of their sources but bear the imprint of varied P--T conditions of melting and contrasted pre-metasomatic histories. This self-consistent partition coefficient dataset thus gives a new scope to understand the complex petrogenesis of K-rich magmas in orogenic settings.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Potassium-rich magmatism represents subordinate magma volumes worldwide but has been observed in many geodynamic settings. Most potassic magmas are thought to derive from very-low degrees of melting of metasomatized mantle lithologies.We performed piston-cylinder experiments to determine trace element partition coefficients between incipient potassic silicate melts and phlogopite textpm pargasite peridotite in the spinel (1 GPa) and garnet stability fields (3 GPa). Most of the rare Earth elements (REEs) are compatible in pargasite but incompatible in phlogopite. Although garnet remains the mineral phase most efficiently fractionating heavy from light REEs (Dgrt=melt Yb =Dgrt=melt La > 750), orthopyroxene can also significantly fractionate REEs, e.g., achieving Dopx=melt Yb =Dopx=melt La > 100 at 3 GPa. Mineral-liquid partition coefficients vary by about one order of magnitude between incipient melts derived from the spinel and garnet stability fields. We thus show that trace element partitioning at the onset of melting is controlled more by pressure (through melt composition) than by the extent of melting. With increasing pressure, Rb and Ba exhibit different behaviors in phlogopite, with Dphl=melt Ba > Dphl=melt Rb at 1 GPa and the opposite at 3 GPa. At 1 GPa, a decrease of melt polymerization (lower NBO/T) with increasing melt fraction translates into a significant decrease of most phlogopite partition coefficients. Finally, we show that resolvable inter-element fractionations do occur when phlogopite- (and pargasite)-bearing peridotite are melted, indicating that trace element ratios are not always faithfully representative of that of their sources but bear the imprint of varied P--T conditions of melting and contrasted pre-metasomatic histories. This self-consistent partition coefficient dataset thus gives a new scope to understand the complex petrogenesis of K-rich magmas in orogenic settings.
78.
Auxerre, M.; Faure, F.; Lequin, D.
The effects of superheating and cooling rate on olivine growth in chondritic liquid Journal Article
In: Meteoritics & Planetary Science, pp. 1–22, 2022.
@article{Auxerre_etal2022,
title = {The effects of superheating and cooling rate on olivine growth in chondritic liquid},
author = {M. Auxerre and F. Faure and D. Lequin},
doi = {10.1111/maps.13830},
year = {2022},
date = {2022-01-01},
journal = {Meteoritics \& Planetary Science},
pages = {1--22},
abstract = {Chondrules, the major constituent of chondrites, are millimeter-sized igneous objects resulting from the crystallization of silicate liquids produced by the partial orcomplete melting of chondritic precursors, whose exact nature remains disputed. Variouschondrule textures are observed as a function of the extent of the initial melting event.Here, we report dynamic crystallization experiments performed with a broad range ofcooling rates (2--750textdegreeCh\^{a}1) from superliquidus or subliquidus initial conditions todemonstrate the control of nucleation on the final chondrule texture. Classical crypto-porphyritic, micro-porphyritic, and porphyritic olivine textures were reproduced insubliquidus experiments in which heterogeneous nucleation dominates. In contrast, we wereunable to reproduce barred olivine textures, regardless of the cooling rates investigated fromsuperliquidus conditions ; instead, macro-porphyritic textures were systematically obtained atlow cooling rates (\<10textdegreeCh\^{a}1). The small number and large size of crystals in the macro-porphyritic texture are consistent with the initial step of superheating and the presence oflong embayments that indicate an initial episode of rapid growth due to delayed nucleation.Crystals then acquired polyhedral shapes during a subsequent episode of slow growth.When the growth rate is too slow to decrease the degree of supersaturation in the liquid, anew episode of rapid growth produces a new generation of melt inclusions},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Chondrules, the major constituent of chondrites, are millimeter-sized igneous objects resulting from the crystallization of silicate liquids produced by the partial orcomplete melting of chondritic precursors, whose exact nature remains disputed. Variouschondrule textures are observed as a function of the extent of the initial melting event.Here, we report dynamic crystallization experiments performed with a broad range ofcooling rates (2--750textdegreeChâ1) from superliquidus or subliquidus initial conditions todemonstrate the control of nucleation on the final chondrule texture. Classical crypto-porphyritic, micro-porphyritic, and porphyritic olivine textures were reproduced insubliquidus experiments in which heterogeneous nucleation dominates. In contrast, we wereunable to reproduce barred olivine textures, regardless of the cooling rates investigated fromsuperliquidus conditions ; instead, macro-porphyritic textures were systematically obtained atlow cooling rates (<10textdegreeChâ1). The small number and large size of crystals in the macro-porphyritic texture are consistent with the initial step of superheating and the presence oflong embayments that indicate an initial episode of rapid growth due to delayed nucleation.Crystals then acquired polyhedral shapes during a subsequent episode of slow growth.When the growth rate is too slow to decrease the degree of supersaturation in the liquid, anew episode of rapid growth produces a new generation of melt inclusions
79.
Wolzlaw, J. F.; Bastian, L.; Guillong, M.; Forni, F.; Laurent, O.; Neukampf, J.; Sulpizio, R.; Chelle-Michou, C.; Bachmann, O.
Garnet petrochronology reveals the lifetime and dynamics of phonolitic magma chambers at Somma-Vesuvius Journal Article
In: Science Advances, vol. 8, pp. eabk2184, 2022.
@article{Wolzlaw_etal2022,
title = {Garnet petrochronology reveals the lifetime and dynamics of phonolitic magma chambers at Somma-Vesuvius},
author = {J. F. Wolzlaw and L. Bastian and M. Guillong and F. Forni and O. Laurent and J. Neukampf and R. Sulpizio and C. Chelle-Michou and O. Bachmann},
doi = {10.1126/sciadv.abk2184},
year = {2022},
date = {2022-01-01},
journal = {Science Advances},
volume = {8},
pages = {eabk2184},
abstract = {Somma-Vesuvius is one of the most iconic active volcanoes with historic and archeological records of numerous hazardous eruptions. Petrologic studies of eruptive products provide insights into the evolution of the magma reservoir before eruption. Here, we quantify the duration of shallow crustal storage and document the evolution of phonolitic magmas before major eruptions of Somma-Vesuvius. Garnet uranium-thorium petrochronology suggests progressively shorter pre-eruption residence times throughout the lifetime of the volcano. Residence times mirror the repose intervals between eruptions, implying that distinct phonolite magma batches were present throughout most of the volcano’s evolution, thereby controlling the eruption dynamics by preventing the ascent of mafic magmas from longer-lived and deeper reservoirs. Frequent lower-energy eruptions during the recent history sample this deeper reservoir and suggest that future Plinian eruptions are unlikely without centuries of volcanic quiescence. Crystal residence times from other volcanoes reveal that long-lived deep-seated reservoirs and transient upper crustal magma chambers are common features of subvolcanic plumbing systems.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Somma-Vesuvius is one of the most iconic active volcanoes with historic and archeological records of numerous hazardous eruptions. Petrologic studies of eruptive products provide insights into the evolution of the magma reservoir before eruption. Here, we quantify the duration of shallow crustal storage and document the evolution of phonolitic magmas before major eruptions of Somma-Vesuvius. Garnet uranium-thorium petrochronology suggests progressively shorter pre-eruption residence times throughout the lifetime of the volcano. Residence times mirror the repose intervals between eruptions, implying that distinct phonolite magma batches were present throughout most of the volcano’s evolution, thereby controlling the eruption dynamics by preventing the ascent of mafic magmas from longer-lived and deeper reservoirs. Frequent lower-energy eruptions during the recent history sample this deeper reservoir and suggest that future Plinian eruptions are unlikely without centuries of volcanic quiescence. Crystal residence times from other volcanoes reveal that long-lived deep-seated reservoirs and transient upper crustal magma chambers are common features of subvolcanic plumbing systems.
80.
Vezinet, A.; Thomassot, E.; Luo, Y.; Sarkar, C.; Pearson, D. G.
In: Geosciences, vol. 12, no. 1, pp. 36, 2022.
@article{Vezinet_etal2022,
title = {Diachronous redistribution of Hf and Nd isotopes at the crystal scale---consequences for the isotopic evolution of a poly-metamorphic crustal terrane},
author = {A. Vezinet and E. Thomassot and Y. Luo and C. Sarkar and D. G. Pearson},
doi = {10.3390/geosciences12010036},
year = {2022},
date = {2022-01-01},
journal = {Geosciences},
volume = {12},
number = {1},
pages = {36},
abstract = {In metamorphic rocks, mineral species react over a range of pressure--temperature conditions that do not necessarily overlap. Mineral equilibration can occur at varied points along the metamorphic pressure--temperature (PT) path, and thus at different times. The sole or dominant use of zircon isotopic compositions to constrain the evolution of metamorphic rocks might then inadvertently skew geological interpretations towards one aspect or one moment of a rock’s history.Here, we present in-situ U--Pb/Sm--Nd isotope analyses of the apatite crystals extracted from two meta-igneous rocks exposed in the Saglek Block (North Atlantic craton, Canada), an Archean metamorphic terrane, with the aim of examining the various signatures and events that they record. The data are combined with published U--Pb/Hf/O isotope compositions of zircon extracted from the same hand-specimens. We found an offset of nearly ca. 1.5 Gyr between U-Pb ages derived fromthe oldest zircon cores and apatite U--Pb/Sm--Nd isotopic ages, and an offset of ca. 200 Ma between the youngest zircon metamorphic overgrowths and apatite. These differences in metamorphic ages recorded by zircon and apatite mean that the redistribution of Hf isotopes (largely hosted in zircon) and Nd isotopes (largely hosted in apatite within these rocks), were not synchronous at the handspecimenscale (\^{a}¤textasciitilde0.001 m3). We propose that the diachronous redistribution of Hf and Nd isotopes and their parent isotopes was caused by the different PT conditions of growth equilibration between zircon and apatite during metamorphism. These findings document the latest metamorphic evolution of the Saglek Block, highlighting the role played by intra-crustal reworking during the late-Archean regional metamorphic event.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In metamorphic rocks, mineral species react over a range of pressure--temperature conditions that do not necessarily overlap. Mineral equilibration can occur at varied points along the metamorphic pressure--temperature (PT) path, and thus at different times. The sole or dominant use of zircon isotopic compositions to constrain the evolution of metamorphic rocks might then inadvertently skew geological interpretations towards one aspect or one moment of a rock’s history.Here, we present in-situ U--Pb/Sm--Nd isotope analyses of the apatite crystals extracted from two meta-igneous rocks exposed in the Saglek Block (North Atlantic craton, Canada), an Archean metamorphic terrane, with the aim of examining the various signatures and events that they record. The data are combined with published U--Pb/Hf/O isotope compositions of zircon extracted from the same hand-specimens. We found an offset of nearly ca. 1.5 Gyr between U-Pb ages derived fromthe oldest zircon cores and apatite U--Pb/Sm--Nd isotopic ages, and an offset of ca. 200 Ma between the youngest zircon metamorphic overgrowths and apatite. These differences in metamorphic ages recorded by zircon and apatite mean that the redistribution of Hf isotopes (largely hosted in zircon) and Nd isotopes (largely hosted in apatite within these rocks), were not synchronous at the handspecimenscale (â¤textasciitilde0.001 m3). We propose that the diachronous redistribution of Hf and Nd isotopes and their parent isotopes was caused by the different PT conditions of growth equilibration between zircon and apatite during metamorphism. These findings document the latest metamorphic evolution of the Saglek Block, highlighting the role played by intra-crustal reworking during the late-Archean regional metamorphic event.