Potassium in the Earth's core?
The partitioning of K and Na between liquid Fe-S-O alloys and silicate melt has been determined over the pressure and temperature range 2.5-24 GPa and 1500-1900°C. In experiments with S-free Fe alloys, the alkali elements show completely lithophile behaviour. When S is added, however, K and Na begin...
| Autores principales: | , |
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| Formato: | Journal article |
| Lenguaje: | English |
| Publicado: |
2002
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| _version_ | 1826297144630312960 |
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| author | Gessmann, C Wood, B |
| author_facet | Gessmann, C Wood, B |
| author_sort | Gessmann, C |
| collection | OXFORD |
| description | The partitioning of K and Na between liquid Fe-S-O alloys and silicate melt has been determined over the pressure and temperature range 2.5-24 GPa and 1500-1900°C. In experiments with S-free Fe alloys, the alkali elements show completely lithophile behaviour. When S is added, however, K and Na begin to enter the Fe-liquid phase and their distribution coefficients D1 (=[I]metal/[I]silicate) correlate strongly with O content (and FeO activity) of the Fe-S-O liquid and with the composition of the silicate melt. For potassium, DK is ~ 1.0 for Fe-sulphide liquid containing 30% S and 8% O. Increasing temperature leads to increasing O solubility in the Fe-sulphide liquid and correspondingly higher values of DK. Increasing pressure on the other hand slightly reduces DK values. Given a planetary core containing 10 wt% S and 4-8 wt% O, then several hundred ppm K would be present in the Fe-sulphide liquid if it segregated at low pressures, e.g. in a small planetary body such as Mars. If, as has recently been suggested, the Earth's core separated at the base of a deep magma ocean, then its highest possible K content is about 250 ppm. The latter would generate approximately 20% of the total heat production of the core. K can only be present in the core, however, if, at some time during its formation, a discrete O-rich FeS liquid separated from the silicate mantle. Finally, the sulphide compositions produced in our experiments imply that a combination of S and O could contribute significantly to the light element content of the Earth's core. © 2002 Elsevier Science B.V. All rights reserved. |
| first_indexed | 2024-03-07T04:27:06Z |
| format | Journal article |
| id | oxford-uuid:cd043293-5ad1-4c84-bf9f-7df044ef3f4d |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T04:27:06Z |
| publishDate | 2002 |
| record_format | dspace |
| spelling | oxford-uuid:cd043293-5ad1-4c84-bf9f-7df044ef3f4d2022-03-27T07:25:52ZPotassium in the Earth's core?Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:cd043293-5ad1-4c84-bf9f-7df044ef3f4dEnglishSymplectic Elements at Oxford2002Gessmann, CWood, BThe partitioning of K and Na between liquid Fe-S-O alloys and silicate melt has been determined over the pressure and temperature range 2.5-24 GPa and 1500-1900°C. In experiments with S-free Fe alloys, the alkali elements show completely lithophile behaviour. When S is added, however, K and Na begin to enter the Fe-liquid phase and their distribution coefficients D1 (=[I]metal/[I]silicate) correlate strongly with O content (and FeO activity) of the Fe-S-O liquid and with the composition of the silicate melt. For potassium, DK is ~ 1.0 for Fe-sulphide liquid containing 30% S and 8% O. Increasing temperature leads to increasing O solubility in the Fe-sulphide liquid and correspondingly higher values of DK. Increasing pressure on the other hand slightly reduces DK values. Given a planetary core containing 10 wt% S and 4-8 wt% O, then several hundred ppm K would be present in the Fe-sulphide liquid if it segregated at low pressures, e.g. in a small planetary body such as Mars. If, as has recently been suggested, the Earth's core separated at the base of a deep magma ocean, then its highest possible K content is about 250 ppm. The latter would generate approximately 20% of the total heat production of the core. K can only be present in the core, however, if, at some time during its formation, a discrete O-rich FeS liquid separated from the silicate mantle. Finally, the sulphide compositions produced in our experiments imply that a combination of S and O could contribute significantly to the light element content of the Earth's core. © 2002 Elsevier Science B.V. All rights reserved. |
| spellingShingle | Gessmann, C Wood, B Potassium in the Earth's core? |
| title | Potassium in the Earth's core? |
| title_full | Potassium in the Earth's core? |
| title_fullStr | Potassium in the Earth's core? |
| title_full_unstemmed | Potassium in the Earth's core? |
| title_short | Potassium in the Earth's core? |
| title_sort | potassium in the earth s core |
| work_keys_str_mv | AT gessmannc potassiumintheearthscore AT woodb potassiumintheearthscore |