Reconstruction of mantle sections beneath Yakutian kimberlite pipes using monomineral thermobarometry

Four original monomineral methods for mantle peridotite associations are used to reconstruct P – T conditions beneath the kimberlite pipes of Yakutia. The clinopyroxene Jd–Di method gives the closest coincidence with Opx barometry in accord with all physico-chemical boundaries. Garnet thermometers c...

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Bibliographic Details
Main Authors: I. V. Ashchepkov, N. P. Pokhilenko, N. V. Vladykin, A. Y. Rotman, V. P. Afanasiev, A. M. Logvinova, S. I. Kostrovitsky, L. N. Pokhilenko, M. A. Karpenko, S. S. Kuligin, E. V. Malygina, Y. B. Stegnitsky, N. A. Alymova, O. S. Khmelnikova
Format: Dataset
Language:unknown
Published: 2016
Subjects:
Geology
Yakutian kimberlite pipes
Opx
Ol
mantle peridotite associations
Cr
pyroxenite layer
monomineral
section
method
horizon
lithologically
kimberlite pipes
Gar’
Yakutia
Online Access:https://doi.org/10.6084/m9.figshare.3454502.v1
https://figshare.com/articles/Reconstruction_of_mantle_sections_beneath_Yakutian_kimberlite_pipes_using_monomineral_thermobarometry/3454502
Description
Summary:Four original monomineral methods for mantle peridotite associations are used to reconstruct P – T conditions beneath the kimberlite pipes of Yakutia. The clinopyroxene Jd–Di method gives the closest coincidence with Opx barometry in accord with all physico-chemical boundaries. Garnet thermometers calibrated using Opx, Gar–Cpx and Ni-garnet thermometers and two variants of barometers were developed separately for pyroxenites and peridotites. A Cr–Sp thermobarometer uses the monomineralic version of the Ol–Sp thermometer and a newly calibrated Cr–Sp barometer. A picroilmenite method uses the Ol–Sp thermometer and a pressure-calibration of the geikielite component. Each mantle column is divided into two (upper and lower) sections by a pyroxenite layer located near 40 kbar. Below the pyroxenite layer, the lower section comprises 3–4 lithologically distinct horizons, with a thermally perturbed layer at the base. Above the pyroxenite layer are 3–5 lithologically distinct horizons, which are more fertile than the lower sections. Splitting of the geotherms characterizes most P – T diagrams and is ascribed to multistage melt percolation processes typical for the mantle beneath kimberlite pipes. The largest pipes are diamond-bearing and have a highly depleted peridotite lens above the asthenospheric layer.

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