Toward a thermal model fo

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• journal_title：American Mineralogist
• Contributor：S.A. Morse
• Publisher：Mineralogical Society of America
• Date：2008-
• Format：text/html
• Language：en
• Identifier：10.2138/am.2008.2792
• journal_abbrev：American Mineralogist
• issn：0003-004X
• volume：93
• issue：1
• firstpage：248
• section：Letters

摘要

<p id="p-1">After a review of history, it is shown that in a comprehensive 1-atm study by pan id="xref-ref-3-1" class="xref-bibr">McBirney and Naslund (1990)pan>, the Skaergaard liquidus temperature is linear from LZa to UZa on stratigraphic height when corrected to pressure. The augite saturation point at LZa/b has the same liquid composition in terms of plagioclase An content as the corresponding point in the Kiglapait intrusion, studied at 5 kbar by pan id="xref-ref-5-1" class="xref-bibr">Morse et al. (2004)pan>. This temperature, 1203 °C at 5 kbar, is transformed to the Skaergaard pressure at LZa/b to a value of 1173 °C. From this fixed point, all other liquidus temperatures at Skaergaard are scaled to mean plagioclase core compositions from a detailed study by pan id="xref-ref-8-1" class="xref-bibr">Toplis et al. (2007)pan>. All such points from LZb to UZa lie, within experimental error, on the regression from McBirney and Naslund, and the further points in UZb and UZc also agree. Plagioclase-based temperatures at the base of LZa exceed the earlier estimates by ~24 °C and imply a possible temperature of 1210 °C in the Hidden Zone. These results provide a good interim model for the Skaergaard liquidus pending further experimental study at the liquidus. p>