Phase equilibria and geochemical constraints on the petrogenesis of high-Ti picrite from the Paleogene East Greenland flood basalt province
Various models have been invoked to explain the petrogenesis and Ti-content bimodality of lavas in large igneous provinces. We performed phase equilibrium experiments on an extremely high-Ti (5.4 wt% TiO2) near-primitive picrite from the base of the Paleogene (~ 55 Ma old) East Greenland Flood Basal...
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ftgfzpotsdam:oai:gfzpublic.gfz-potsdam.de:item_2737913 2023-05-15T16:03:36+02:00 Phase equilibria and geochemical constraints on the petrogenesis of high-Ti picrite from the Paleogene East Greenland flood basalt province Zhang, Y. Hou, T. Veksler, I. Lesher, C. Namur, O. 2018 https://gfzpublic.gfz-potsdam.de/pubman/item/item_2737913 unknown info:eu-repo/semantics/altIdentifier/doi/10.1016/j.lithos.2017.11.011 info:eu-repo/semantics/altIdentifier/urn/http://doi.crossref.org/servlet/query?format=unixref&pid=bib@gfz-potsdam.de&id=10.1016/j.lithos.2017.11.011 https://gfzpublic.gfz-potsdam.de/pubman/item/item_2737913 Lithos info:eu-repo/semantics/article 2018 ftgfzpotsdam https://doi.org/10.1016/j.lithos.2017.11.011 2022-09-14T05:56:54Z Various models have been invoked to explain the petrogenesis and Ti-content bimodality of lavas in large igneous provinces. We performed phase equilibrium experiments on an extremely high-Ti (5.4 wt% TiO2) near-primitive picrite from the base of the Paleogene (~ 55 Ma old) East Greenland Flood Basalt Province to constrain the mantle melting source. This sample has low An content, a steep rare earth element (REE) profile, and is enriched in incompatible trace elements. Near-liquidus phase relations determined over pressures of 1 atm to 1.5 GPa and temperatures from 1094 to 1400 °C reveal that the high-Ti picritic glasses are multi-saturated with olivine (Ol) + orthopyroxene (Opx) at pressures around 1 GPa, but have only Ol or Opx on the liquidus at lower and higher pressures, respectively. This indicates that the primitive melt was last equilibrated with olivine-free rocks, e.g., pyroxenite before it left the lithospheric mantle. Considering the high CaO/Al2O3 ratio (1.14) of our starting material and the presence of low-Ca pyroxene (pigeonite) at high pressure in our experiments, we propose that garnet pyroxenite was present in the mantle source. Residual garnet in the source could adequately explain the low Al2O3 content (7.92 wt%) and steep heavy REE patterns of the picrite. The high Ni content of the picritic lava (ca. 460 ppm) at 13 wt% MgO also supports a source depleted in olivine. We suggest that the high degree of enrichment in incompatible elements results from melting of a metasomatized mantle. Based on geochemical modelling, we propose that the mantle source contains 5% Ti-enriched amphibole and that moderate partial melting (15–20%) of this source can produce the high-Ti picritic lavas of East Greenland. Article in Journal/Newspaper East Greenland Greenland GFZpublic (German Research Centre for Geosciences, Helmholtz-Zentrum Potsdam) Greenland Lithos 300-301 20 32 |
institution |
Open Polar |
collection |
GFZpublic (German Research Centre for Geosciences, Helmholtz-Zentrum Potsdam) |
op_collection_id |
ftgfzpotsdam |
language |
unknown |
description |
Various models have been invoked to explain the petrogenesis and Ti-content bimodality of lavas in large igneous provinces. We performed phase equilibrium experiments on an extremely high-Ti (5.4 wt% TiO2) near-primitive picrite from the base of the Paleogene (~ 55 Ma old) East Greenland Flood Basalt Province to constrain the mantle melting source. This sample has low An content, a steep rare earth element (REE) profile, and is enriched in incompatible trace elements. Near-liquidus phase relations determined over pressures of 1 atm to 1.5 GPa and temperatures from 1094 to 1400 °C reveal that the high-Ti picritic glasses are multi-saturated with olivine (Ol) + orthopyroxene (Opx) at pressures around 1 GPa, but have only Ol or Opx on the liquidus at lower and higher pressures, respectively. This indicates that the primitive melt was last equilibrated with olivine-free rocks, e.g., pyroxenite before it left the lithospheric mantle. Considering the high CaO/Al2O3 ratio (1.14) of our starting material and the presence of low-Ca pyroxene (pigeonite) at high pressure in our experiments, we propose that garnet pyroxenite was present in the mantle source. Residual garnet in the source could adequately explain the low Al2O3 content (7.92 wt%) and steep heavy REE patterns of the picrite. The high Ni content of the picritic lava (ca. 460 ppm) at 13 wt% MgO also supports a source depleted in olivine. We suggest that the high degree of enrichment in incompatible elements results from melting of a metasomatized mantle. Based on geochemical modelling, we propose that the mantle source contains 5% Ti-enriched amphibole and that moderate partial melting (15–20%) of this source can produce the high-Ti picritic lavas of East Greenland. |
format |
Article in Journal/Newspaper |
author |
Zhang, Y. Hou, T. Veksler, I. Lesher, C. Namur, O. |
spellingShingle |
Zhang, Y. Hou, T. Veksler, I. Lesher, C. Namur, O. Phase equilibria and geochemical constraints on the petrogenesis of high-Ti picrite from the Paleogene East Greenland flood basalt province |
author_facet |
Zhang, Y. Hou, T. Veksler, I. Lesher, C. Namur, O. |
author_sort |
Zhang, Y. |
title |
Phase equilibria and geochemical constraints on the petrogenesis of high-Ti picrite from the Paleogene East Greenland flood basalt province |
title_short |
Phase equilibria and geochemical constraints on the petrogenesis of high-Ti picrite from the Paleogene East Greenland flood basalt province |
title_full |
Phase equilibria and geochemical constraints on the petrogenesis of high-Ti picrite from the Paleogene East Greenland flood basalt province |
title_fullStr |
Phase equilibria and geochemical constraints on the petrogenesis of high-Ti picrite from the Paleogene East Greenland flood basalt province |
title_full_unstemmed |
Phase equilibria and geochemical constraints on the petrogenesis of high-Ti picrite from the Paleogene East Greenland flood basalt province |
title_sort |
phase equilibria and geochemical constraints on the petrogenesis of high-ti picrite from the paleogene east greenland flood basalt province |
publishDate |
2018 |
url |
https://gfzpublic.gfz-potsdam.de/pubman/item/item_2737913 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
East Greenland Greenland |
genre_facet |
East Greenland Greenland |
op_source |
Lithos |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1016/j.lithos.2017.11.011 info:eu-repo/semantics/altIdentifier/urn/http://doi.crossref.org/servlet/query?format=unixref&pid=bib@gfz-potsdam.de&id=10.1016/j.lithos.2017.11.011 https://gfzpublic.gfz-potsdam.de/pubman/item/item_2737913 |
op_doi |
https://doi.org/10.1016/j.lithos.2017.11.011 |
container_title |
Lithos |
container_volume |
300-301 |
container_start_page |
20 |
op_container_end_page |
32 |
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1766399281603805184 |