A review of the composition and chemistry of peridotite mantle xenoliths in volcanic rocks from Antarctica and their relevance to petrological and geophysical models for the lithospheric mantle

2021 ◽  
pp. M56-2021-26
Author(s):  
A. P. Martin
Keyword(s):  
Lithospheric Mantle ◽  
Volcanic Rocks ◽  
Mantle Peridotite ◽  
Mantle Xenoliths ◽  
Future Research ◽  
Isostatic Adjustment ◽  
Peridotite Mantle ◽  
Geodynamic Models ◽  
The Antarctic ◽  
First Time

AbstractThis chapter reviews the geochemistry and petrology of mantle peridotite xenoliths from across Antarctica, including parameters that are of most relevance to geophysical studies. This Memoir is the first time such a complete overview of the chemistry of Antarctic mantle xenoliths has been available and Antarctica should no longer be the ignored continent in studies of mantle xenoliths in volcanic rocks. Xenoliths indicate that the chemistry, heat flow and water content of the Antarctic lithospheric mantle varies regionally at scales of one to thousands of kilometres. The prevalence of variability in xenoliths suggests that the Antarctic mantle is ubiquitously heterogeneous. This has important, yet unquantified, implications for interpreting geophysical data and for reference Earth models used in Antarctic geophysical studies. Information about and interpretations of Antarctic mantle xenoliths can be linked to studies from once adjacent continental blocks in Africa, India, Australia, New Zealand and South America. Together, this can improve understanding of the mantle contribution to glacial isostatic adjustment and geodynamic models to show how the Antarctic mantle fits with adjacent continents in the puzzle of lithospheric blocks. Numerous, fundamental and important research questions remain unanswered making further study of the Antarctic mantle an exciting prospect for future research.

scholarly journals Antarctic Palaeotopography

2021 ◽  
pp. M56-2020-7
Author(s):  
Guy J. G. Paxman
Keyword(s):  
Ice Sheet ◽  
Future Research ◽  
Dynamic Topography ◽  
Antarctic Ice Sheet ◽  
Isostatic Adjustment ◽  
Subglacial Topography ◽  
Mantle Processes ◽  
Ice Sheet Dynamics ◽  
The Antarctic

AbstractThe development of a robust understanding of the response of the Antarctic Ice Sheet to present and projected future climatic change is a matter of key global societal importance. Numerical ice sheet models that simulate future ice sheet behaviour are typically evaluated with recourse to how well they reproduce past ice sheet behaviour, which is constrained by the geological record. However, subglacial topography, a key boundary condition in ice sheet models, has evolved significantly throughout Antarctica's glacial history. Since mantle processes play a fundamental role in the generation and modification of topography over geological timescales, an understanding of the interactions between the Antarctic mantle and palaeotopography is crucial for developing more accurate simulations of past ice sheet dynamics. This chapter provides a review of the influence of the Antarctic mantle on the long-term evolution of the subglacial landscape, through processes including structural inheritance, flexural isostatic adjustment, lithospheric cooling and thermal subsidence, volcanism and dynamic topography. The uncertainties associated with reconstructing these processes through time are discussed, as are important directions for future research and the implications of the evolving subglacial topography for the response of the Antarctic Ice Sheet to climatic and oceanographic change.

Ultramafic mantle xenoliths in the Late Cenozoic Volcanic rocks of the Antarctic Peninsula and Jones Mountains, West Antarctica

2021 ◽  
pp. M56-2019-44
Author(s):  
Philip T. Leat ◽  
Aidan J. Ross ◽  
Sally A. Gibson
Keyword(s):  
Antarctic Peninsula ◽  
Upper Mantle ◽  
Lithospheric Mantle ◽  
Volcanic Rocks ◽  
Oceanic Lithosphere ◽  
Incompatible Trace Element ◽  
Mantle Xenoliths ◽  
South Shetland Islands ◽  
West Antarctica ◽  
Gondwana Margin

AbstractAbundant mantle-derived ultramafic xenoliths occur in Cenozoic (7.7-1.5 Ma) mafic alkaline volcanic rocks along the former active margin of West Antarctica, that extends from the northern Antarctic Peninsula to Jones Mountains. The xenoliths are restricted to post-subduction volcanic rocks that were emplaced in fore-arc or back-arc positions relative to the Mesozoic-Cenozoic Antarctic Peninsula volcanic arc. The xenoliths are spinel-bearing, include harzburgites, lherzolites, wehrlites and pyroxenites, and provide the only direct evidence of the composition of the lithospheric mantle underlying most of the margin. The harzburgites may be residues of melt extraction from the upper mantle (in a mid-ocean ridge type setting), that accreted to form oceanic lithosphere, which was then subsequently tectonically emplaced along the active Gondwana margin. An exposed highly-depleted dunite-serpentinite upper mantle complex on Gibbs Island, South Shetland Islands, supports this interpretation. In contrast, pyroxenites, wehrlites and lherzolites reflect percolation of mafic alkaline melts through the lithospheric mantle. Volatile and incompatible trace element compositions imply that these interacting melts were related to the post-subduction magmatism which hosts the xenoliths. The scattered distribution of such magmatism and the history of accretion suggest that the dominant composition of sub-Antarctic Peninsula lithospheric mantle is likely to be harzburgitic.

scholarly journals Redox state of southern Tibetan upper mantle and ultrapotassic magmas

Geology ◽  
2020 ◽  
Vol 48 (7) ◽  
pp. 733-736 ◽  
Author(s):  
Weikai Li ◽  
Zhiming Yang ◽  
Massimo Chiaradia ◽  
Yong Lai ◽  
Chao Yu ◽  
...  
Keyword(s):  
Upper Mantle ◽  
Lithospheric Mantle ◽  
Redox State ◽  
Volcanic Rocks ◽  
Mantle Xenoliths ◽  
Continental Plate ◽  
Cratonic Mantle ◽  
Tectonic Settings ◽  
Mantle Condition ◽  
Typical Range

Abstract The redox state of Earth’s upper mantle in several tectonic settings, such as cratonic mantle, oceanic mantle, and mantle wedges beneath magmatic arcs, has been well documented. In contrast, oxygen fugacity () data of upper mantle under orogens worldwide are rare, and the mechanism responsible for the mantle condition under orogens is not well constrained. In this study, we investigated the of mantle xenoliths derived from the southern Tibetan lithospheric mantle beneath the Himalayan orogen, and that of postcollisional ultrapotassic volcanic rocks hosting the xenoliths. The of mantle xenoliths ranges from ΔFMQ = +0.5 to +1.2 (where ΔFMQ is the deviation of log from the fayalite-magnetite-quartz buffer), indicating that the southern Tibetan lithospheric mantle is more oxidized than cratonic and oceanic mantle, and it falls within the typical range of mantle wedge values. Mineralogical evidence suggests that water-rich fluids and sediment melts liberated from both the subducting Neo-Tethyan oceanic slab and perhaps the Indian continental plate could have oxidized the southern Tibetan lithospheric mantle. The conditions of ultrapotassic magmas show a shift toward more oxidized conditions during ascent (from ΔFMQ = +0.8 to +3.0). Crustal evolution processes (e.g., fractionation) could influence magmatic , and thus the redox state of mantle-derived magma may not simply represent its mantle source.

Fe-Cu-S rich melts in the subcontinental lithospheric mantle: insight from the Lower Silesian (SW Poland) xenoliths

2020 ◽  
Author(s):  
Hubert Mazurek ◽  
Jakub Ciążela ◽  
Magdalena Matusiak-Małek ◽  
Jacek Puziewicz ◽  
Theodoros Ntaflos
Keyword(s):  
Lithospheric Mantle ◽  
Volcanic Rocks ◽  
Oceanic Lithosphere ◽  
Mantle Xenoliths ◽  
Subcontinental Lithospheric Mantle ◽  
Origin And Evolution ◽  
Depleted Mantle ◽  
Group A ◽  
Sw Poland ◽  
Group B

<p>Migration of strategic metals through the lithospheric mantle can be tracked by sulfides in mantle xenoliths. Cenozoic mafic volcanic rocks from the SW Poland (Lower Silesia, Bohemian Massif) host a variety of subcontinental lithospheric mantle (SCLM) xenoliths. To understand metal migration in the SCLM we studied metal budget of peridotites from the Wilcza Góra basanite and their metasomatic history.</p><p>The Wilcza Góra xenoliths are especially appropriate to study metasomatic processes as they consist of 1) peridotites with Ol<sub>Fo=89.1-91.5 </sub>representing depleted mantle (group A); 2) peridotites with Ol<sub>Fo=84.2-89.2</sub> representing melt-metasomatized mantle (group B), as well as 3) hornblende-clinopyroxenites and websterites with Ol<sub>Fo=77.2-82.5</sub> representing former melt  channels (group C; Matusiak-Małek et al., 2017). The inherent sulfides are either interstitial or enclosed in the silicates. High-temperature exsolutions of pyrrhotite (Po), pentlandite (Pn) and chalcopyrite (Ccp) indicate magmatic origin of the sulfides.</p><p>The three peridotitic groups differ by sulfide mode and composition. The sulfide modes are enhanced in group C (0.022-0.963 vol.‰) and group B (<0.028 vol. ‰) with respect to group A (<0.002 vol.‰). The sulfides of group C are Ni-poor and Fe-Cu-rich as reflected in their mineral composition (Po<sub>55-74</sub>Ccp<sub>1-2</sub>Pn<sub>24-44</sub> in group A, Po<sub>67-85</sub>Ccp<sub>1-6</sub>Pn<sub>14-33</sub>, in group B and Po<sub>80-97</sub>Ccp<sub>1-7</sub>Pn<sub>2-20 </sub>in group C) and major element chemical composition. Ni/(Ni+Fe) of pentlandite is the lowest in group C (~0.25) and the highest in group A (0.54-0.61). Cu/(Cu+Fe) of chalcopyrite is 0.32-0.49 in group C contrasting to~0.50 in groups A and B. </p><p>The sulfide-rich xenoliths of group C indicate an important role of pyroxenitic veins in transporting Fe-Cu-S-rich melts from the upper mantle to the crust. However, the moderately enhanced sulfide modes in melt-mantle reaction zones represented by xenoliths of group B demonstrate that the upper continental mantle is refertilized with these melts during their ascent. Hence, significant portion of S and metals remains in the mantle never reaching the crust, as has been previously observed in the oceanic lithosphere (Ciazela et al., 2018).</p><p> </p><p><strong>Acknowledgments:</strong> This study was supported by the NCN project no. UMO-2014/15/B/ST10/00095. The EPMA analyses were funded from the Polish-Austrian project WTZ PL 08/2018.</p><p> </p><p><strong>References:</strong></p><p>Ciazela, J., Koepke, J., Dick, H. J. B., Botcharnikov, R., Muszynski, A., Lazarov, M., Schuth, S., Pieterek, B. & Kuhn, T. (2018). Sulfide enrichment at an oceanic crust-mantle transition zone: Kane Megamullion (23 N, MAR). Geochimica et Cosmochimica Acta, 230, 155-189</p><p>Matusiak-Małek, M., Puziewicz, J., Ntaflos, T., Grégoire, M., Kukuła, A. & Wojtulek P.   M. (2017). Origin and evolution of rare amphibole-bearing mantle peridotites from Wilcza Góra (SW Poland), Central Europe. Lithos 286–287, 302–323.</p>

scholarly journals Crystal preferred orientation of olivine in mantle xenoliths from Catalonia (NE Spain) Orientación cristalina preferente del olivino en xenolitos mantélicos de Cataluña (NE de España)

2018 ◽  
Vol 36 (36) ◽  
pp. 119
Author(s):  
M. Fernández-Roig ◽  
G. Galán ◽  
E. Mariani
Keyword(s):  
Lithospheric Mantle ◽  
Fiber Type ◽  
Volcanic Rocks ◽  
Preferred Orientation ◽  
Mantle Xenoliths ◽  
Fiber Types ◽  
Electron Backscattered Diffraction ◽  
Crystal Preferred Orientation ◽  
Diffraction Patterns ◽  
Península Ibérica

Abstract: Mantle xenoliths in Neogene-Quaternary alkaline volcanic rocks from the Catalan Volcanic Zone indicate that ≪anhydrous≫ spinel lherzolites, harzburgites and much subordinate olivine websterites form the lithospheric mantle of NE Iberian Peninsula. Olivine crystal preferred orientation, determined by indexation of electron-backscattered diffraction patterns, provides three types of deformation fabric: a dominant [010]-fiber type in peridotites and websterites equilibrated at high temperature, and subordinate orthorhombic and [100]-fiber types, which appear mostly in porphyroclas tic and equigranular lherzolites equilibrated at lower temperature.Keywords: Lithospheric mantle, lherzolites, harzburgites, websterites, olivine, deformation fabric.Resumen: Los xenolitos mantelitos en lavas alcalinas neógeno-cuaternarias de la Zona Volcánica de Cataluña indican que lherzolitas y harzburgitas ≪ anhidras≫  y con espinela son las rocas predominantes en el manto litosférico del NE de la Península Ibérica, con presencia también subordinada de websteritas olivínicas. Las orientaciones cristalográficas preferentes del olivino, determinadas por indexación de los espectros de difracción de electrones retrodispersados, muestran tres tipos de fábrica de deformación: una dominante, tipo axial [010], en peridotitas y websteritas equilibradas a alta temperatura, y otras subordinadas, de tipo ortorrómbico y axial [100], que aparecen en lherzolitas porfidoclásticas y equigranulares equilibradas a menor temperatura.Palabras clave: Manto litosférico, lherzolitas, harzburgitas, websterita, olivino, fábricas de deformación

Lichens of the Oasis Molodyozhnyi and adjacent areas (Enderby Land, Antarctic)

2013 ◽  
Vol 47 ◽  
pp. 167-178 ◽  
Author(s):  
M. P. Andreev
Keyword(s):  
Liquid Water ◽  
Climate Conditions ◽  
Water Ice ◽  
Buellia Frigida ◽  
Antarctic Continent ◽  
Harsh Climate ◽  
The Antarctic ◽  
First Time ◽  
Lichen Flora

Lichen flora and vegetation in the vicinity of the Russian base «Molodyozhnaya» (Enderby Land, Antarctica) were investigated in 2010–2011 in details for the first time. About 500 specimens were collected in 100 localities in all available ecotopes. The lichen flora is the richest in the region and numbers 39 species (21 genera, 11 families). The studied vegetation is very poor and sparse, but typical for coastal oases of the Antarctic continent. The poorness is caused by the extremely harsh climate conditions, insufficient availability of liquid water, ice-free land, and high insolation levels. The dominant and most common lichens are Rinodina olivaceobrunnea, Amandinea punctata, Candelariella flava, Physcia caesia, Caloplaca tominii, Lecanora expectans, Caloplaca ammiospila, Lecidea cancriformis, Pseudephebe minuscula, Lecidella siplei, Umbilicaria decussata, Buellia frigida, Lecanora fuscobrunnea, Usnea sphacelata, Lepraria and Buellia spp.

A Bibliometric Review on Outcome-Based Learning for Graduate Employability: Mapping the Research Front

2021 ◽  
pp. 002205742110164
Author(s):  
Mohammad Zahir Raihan ◽  
Md. Abul Kalam Azad
Keyword(s):  
Research Trend ◽  
Future Research ◽  
Research Front ◽  
Important Research ◽  
R Software ◽  
Future Research Agenda ◽  
Graduate Employability ◽  
Important Research Topic ◽  
Bibliometric Review ◽  
First Time

The outcome-based learning for graduate employability in higher education has been an important research topic among the policymakers, academicians, and researchers over the years. Yet, no bibliometric review on this topic has been published. This study, for the first time, examines bibliometric analysis on this topic examining current research trend and future research agenda. The bibliometrix package in R software and VOSviewer software are used for visualization and interpretation of results. A content analysis is performed to manually examine the bibliometric results.

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