Strength variations of the Australian continent: Effects of temperature, strain rate, and rheological changes

Tesauro, Magdala; Kaban, Mikhail K.; Petrunin, Alexey G.; Aitken, Alan

doi:10.1016/j.gloplacha.2020.103322

Cited by 7 publications

(4 citation statements)

References 69 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In conclusion, a novel perspective is applied to the mineral assemblage of olivine + clinopyroxene + orthopyroxene + spinel + phlogopite + amphibole in mantle xenoliths and it can provide further restraints about the effective reducing/oxidizing state of the lithospheric mantle. In addition, this petrological study provides a new finding for a potential geotherm in the southeast Australian upper mantle, which is fully consistent with the results of previous thermal models 86 – 89 .…”

Section: Discussionsupporting

confidence: 90%

“…Marked in blue and in red are the P–T regions geologically incoherent and coherent with (spinel-bearing) mantle lithologies, respectively. The modelled P–T locus crosses at ~ 2.3 GPa/1190 K the geotherm calculated for this study (blue thick line) from the analysis of surface heat flow data and combining seismic tomography gravity data 88 , 89 . This P–T path is slightly “cooler” with respect to the Australian geotherm’s field (grey field) from literature 86 , 87 .…”

Section: Discussionmentioning

confidence: 53%

“…The Australian mantle domain that stabilized the Mount Leura xenolith mineral assemblages under study is placed in this region. Using the recent thermal model of the crust and upper mantle of the Australian continent, obtained from the analysis of surface heat flow data and combining seismic tomography and gravity data 88 , 89 , it was possible to calculate the geotherm of this mantle column down to 200 km of depth in the proximity of the xenolith location (38°14′41.0"S; 143°09′27.5"E). The new proposed geotherm (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…The new proposed geotherm (Fig. 5 ) takes into account the mantle xenolith’s petrological evidence (part of this study) of the extensive re-fertilization that occurred during the Proterozoic tectonic events 88 , 89 . The resulting geotherm, specifically related to the mantle column of the Mount Leura xenoliths, is slightly “cooler” than the Australian mantle geotherms’ field (2.3 GPa /1290 K) and intersects the modelled P – T locus of the amphibole-phlogopite equilibrium at ~ 2.3 GPa/1190 K. This P – T point represents the plausible thermal-baric conditions of the mantle region (~ 70 km depth) related to the Mount Leura xenolith provenance.…”

Section: Discussionmentioning

confidence: 99%

See 3 more Smart Citations

Phlogopite-pargasite coexistence in an oxygen reduced spinel-peridotite ambient

Bonadiman

Brombin

Andreozzi

et al. 2021

Sci Rep

Self Cite

View full text Add to dashboard Cite

The occurrence of phlogopite and amphibole in mantle ultramafic rocks is widely accepted as the modal effect of metasomatism in the upper mantle. However, their simultaneous formation during metasomatic events and the related sub-solidus equilibrium with the peridotite has not been extensively studied. In this work, we discuss the geochemical conditions at which the pargasite-phlogopite assemblage becomes stable, through the investigation of two mantle xenoliths from Mount Leura (Victoria State, Australia) that bear phlogopite and the phlogopite + amphibole (pargasite) pair disseminated in a harzburgite matrix. Combining a mineralogical study and thermodynamic modelling, we predict that the P–T locus of the equilibrium reaction pargasite + forsterite = Na-phlogopite + 2 diopside + spinel, over the range 1.3–3.0 GPa/540–1500 K, yields a negative Clapeyron slope of -0.003 GPa K–1 (on average). The intersection of the P–T locus of supposed equilibrium with the new mantle geotherm calculated in this work allowed us to state that the Mount Leura xenoliths achieved equilibrium at 2.3 GPa /1190 K, that represents a plausible depth of ~ 70 km. Metasomatic K-Na-OH rich fluids stabilize hydrous phases. This has been modelled by the following equilibrium equation: 2 (K,Na)-phlogopite + forsterite = 7/2 enstatite + spinel + fluid (components: Na2O,K2O,H2O). Using quantum-mechanics, semi-empirical potentials, lattice dynamics and observed thermo-elastic data, we concluded that K-Na-OH rich fluids are not effective metasomatic agents to convey alkali species across the upper mantle, as the fluids are highly reactive with the ultramafic system and favour the rapid formation of phlogopite and amphibole. In addition, oxygen fugacity estimates of the Mount Leura mantle xenoliths [Δ(FMQ) = –1.97 ± 0.35; –1.83 ± 0.36] indicate a more reducing mantle environment than what is expected from the occurrence of phlogopite and amphibole in spinel-bearing peridotites. This is accounted for by our model of full molecular dissociation of the fluid and incorporation of the O-H-K-Na species into (OH)-K-Na-bearing mineral phases (phlogopite and amphibole), that leads to a peridotite metasomatized ambient characterized by reduced oxygen fugacity.

show abstract

Section: Discussionsupporting

confidence: 90%