<sup>40</sup>Ar/<sup>39</sup>Ar ages in mantle xenolith phlogopites: determining the ages of multiple lithospheric mantle events and diatreme ascent rates
in southern Africa and Malaita, Solomon Islands
Jo-Anne Wartho
Simon P. Kelley
10.6084/m9.figshare.3454190.v1
https://geolsoc.figshare.com/articles/dataset/_sup_40_sup_Ar_sup_39_sup_Ar_ages_in_mantle_xenolith_phlogopites_determining_the_ages_of_multiple_lithospheric_mantle_events_and_diatreme_ascent_rates___in_southern_Africa_and_Malaita_Solomon_Islands/3454190
<p>Kimberlites are extraordinary natural phenomena, ascending through the Earth’s lithosphere, entraining xenoliths, to erupt
at the surface within hours to days of their inception deep within the lithospheric mantle. With the realization that some
Ar/Ar phlogopite grain core ages may be indicative of geological events, we have undertaken high spatial resolution Ar/Ar
dating of phlogopites in xenoliths and megacrysts from Kimberley, Monastery and Letseng in southern Africa, and Malaita, in
the Solomon Islands, to est whether other mantle phlogopite cores may yield meaningful ages.
</p> <p>Modelling of Ar diffusive loss profiles from phlogopite grain boundaries to cores provides information on both the eruption
age and the duration of outgassing within the kimberlite magma, and hence yields estimates on diatreme ascent rates. The ascent
durations are very similar for all of the southern African pipes studied, yielding durations of 0.9–6.9 days, assuming an
average kimberlite magma temperature of 1000 °C. These can be compared to estimates from phlogopite xenoliths from Siberian
diamond-bearing kimberlites yielding ascent durations of 2–15 hours (assuming the same magma temperature).
</p>
2016-06-21 11:57:40
Ar diffusive loss profiles
mantle xenolith phlogopites
lithospheric mantle events
Solomon Islands Kimberlites
phlogopite grain boundaries
kimberlite magma temperature
diatreme ascent rates
ascent durations
mantle phlogopite cores
Geology