Pervasive, tholeiitic refertilisation and heterogeneous metasomatism in Northern Victoria Land lithospheric mantle (Antarctica)

Lithos ◽  
2016 ◽  
Vol 248-251 ◽  
pp. 493-505 ◽  
Author(s):  
Beatrice Pelorosso ◽  
Costanza Bonadiman ◽  
Massimo Coltorti ◽  
Barbara Faccini ◽  
Massimiliano Melchiorre ◽  
...  
Keyword(s):  
Lithospheric Mantle ◽  
Victoria Land

Nature and evolution of the northern Victoria Land lithospheric mantle (Antarctica) as revealed by ultramafic xenoliths

2021 ◽  
pp. M56-2020-11
Author(s):  
Massimo Coltorti ◽  
Costanza Bonadiman ◽  
Federico Casetta ◽  
Barbara Faccini ◽  
Pier Paolo Giacomoni ◽  
...  
Keyword(s):  
Lithospheric Mantle ◽  
Evolutionary History ◽  
Major Elements ◽  
Mantle Xenoliths ◽  
Victoria Land ◽  
Ultramafic Xenoliths ◽  
Large Sector ◽  
Subcontinental Lithosphere ◽  
Comparative Manner

AbstractA review of northern Victoria Land ultramafic xenoliths, collected and studied over more than 30 years, was carried out. More than 200 samples were gathered and characterized in a coherent and comparative manner, both for mantle-derived and cumulate xenoliths. Almost 2000 analyses of major elements and more than 300 analyses of trace elements of in situ and separated olivine, pyroxenes, amphibole, spinel and glass were taken into consideration. Particular attention was devoted to mantle lithologies in order to emphasize the composition and the evolution of this portion of the subcontinental lithosphere. The three main localities in northern Victoria Land where mantle xenoliths were found (i.e. Mount Melbourne (Baker Rocks), Greene Point and Handler Ridge), over a >200 km distance, were described and compared with ultramafic xenoliths in three other localities (Harrow Peaks, Browning Pass and Mount Overlord) that are mainly cumulate in nature. Altogether, these data enabled us to reconstruct a long evolutionary history, from old depletion to most recent refertilization and metasomatic events, for this large sector of the northern Victoria Land subcontinental lithospheric mantle.

Oxo-amphiboles in mantle xenoliths: evidence for H2O-rich melt interacting with the lithospheric mantle of Harrow Peaks (Northern Victoria Land, Antarctica)

2015 ◽  
Vol 109 (6) ◽  
pp. 741-759 ◽  
Author(s):  
S. Gentili ◽  
C. Bonadiman ◽  
C. Biagioni ◽  
P. Comodi ◽  
M. Coltorti ◽  
...  
Keyword(s):  
Lithospheric Mantle ◽  
Mantle Xenoliths ◽  
Victoria Land

Depletion, metasomatism and refertilisation in the Sub-Continental Lithospheric Mantle beneath northern Victoria Land (Antarctica): a review

2021 ◽  
Author(s):  
Massimo Coltorti ◽  
Costanza Bonadiman ◽  
Federico Casetta ◽  
Barbara Faccini ◽  
Pier Paolo Giacomoni ◽  
...  
Keyword(s):  
Lithospheric Mantle ◽  
Large Scale ◽  
Ross Sea ◽  
Mantle Xenoliths ◽  
Rift System ◽  
Stability Field ◽  
Alkaline Magmatism ◽  
Metasomatic Process ◽  
Victoria Land ◽  
Continental Lithospheric Mantle

<p>Assessing the nature and evolution of the Sub-Continental Lithospheric Mantle (SCLM) is crucial to understand the dynamics of Earth’s interior and the global scale tectono-magmatic processes. The study of ultramafic xenoliths brought to the surface in specific context, such as northern Victoria Land (Antarctica), is a key to investigate how the SCLM bear witness of large-scale geodynamic episodes. Indeed, the Antarctica lithosphere was involved into three main tectono-magmatic episodes since Paleozoic, i.e. the 550-110 Ma Ross subduction, the Jurassic (~182 Ma) Ferrar magmatism and the Cenozoic alkaline magmatism responsible for the opening of the West Antarctic Rift System (WARS).</p><p>In this study, a review of the petrological and geochemical features of >200 mantle-derived and cumulate xenoliths brought to the surface at Baker Rocks, Greene Point, Handler Ridge, Harrow Peaks, Browning Pass and Mount Overlord enabled us to reconstruct the main depletion and enrichment processes that took place in the Antarctica SCLM. Strong depletion is recorded by Greene Point lherzolites and harzburgites (18-21%), which likely began melting in the garnet facies and terminated in the spinel facies (Perinelli et al. 2006), whereas mild melt extraction in the spinel stability field was hypothesized at Baker Rocks and Handler Ridge (12-16% and 7-13% melting, respectively). The onset of the Jurassic Ferrar large magmatic event is testified by both the refertilisation in Greene Point-Baker Rocks peridotites and the appearance of cumulate orthopyroxenites/olivine-websterites at Harrow Peaks and Baker Rocks. Late enrichment process/es took place in concomitance with the Cenozoic alkaline magmatism of the WARS, resulting in both cryptic and modal metasomatism and overprinting earlier chemical modifications. This metasomatism was particularly effective at Baker Rocks, as shown by the increase of clinopyroxene abundance, its trace element enrichment and the formation of amphibole disseminated and in veins. Clinopyroxene composition in Cenozoic cumulate rocks matches the enrichment path observed in the peridotites, supporting the link between the last metasomatic process and the recent alkaline magmatism.</p><p>Among mantle xenoliths populations, Greene Point record the highest T-P (870-1059 °C; 0.8-1.6 GPa) and the least oxidized conditions (fO<sub>2</sub> down to -2/-3 ΔFMQ). Cumulate rocks yield the highest fO<sub>2</sub> (up to +1.5 ΔFMQ), at T varying between 900 and 1150°C, approximating the conditions of crystallizing melts. No discrepancies in fO<sub>2</sub> emerged between amphibole-bearing and amphibole-free peridotites, ruling out a strict correlation between amphibole stability, H<sub>2</sub>O activity and fO<sub>2</sub>. Nevertheless, the alkaline metasomatic event, which led to amphibole formation, caused a remarkable increase in the H<sub>2</sub>O content of the system. In fact, anhydrous peridotites preserve bulk H<sub>2</sub>O contents ≤128 ppm, while lherzolites with disseminated amphibole and hornblendites have H<sub>2</sub>O contents as up to 354-1120 ppm and 1.42 wt%, respectively.</p><p> </p><p>Perinelli, C., et al. 2006. Geochemical and O-isotope constraints on the evolution of lithospheric mantle in the Ross Sea rift area (Antarctica). Contributions to Mineralogy and Petrology, 151(3), 245-266.</p>

Preferential localized thinning of lithospheric mantle in the melt-poor Malawi Rift

2020 ◽  
Vol 13 (8) ◽  
pp. 584-589
Author(s):  
Emily Hopper ◽  
James B. Gaherty ◽  
Donna J. Shillington ◽  
Natalie J. Accardo ◽  
Andrew A. Nyblade ◽  
...  
Keyword(s):  
Lithospheric Mantle
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