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<front>
<journal-meta>
<journal-id journal-id-type="archive">gsminmag</journal-id>
<journal-title>Mineralogical Magazine</journal-title>
<abbrev-journal-title abbrev-type="full">Mineralogical Magazine</abbrev-journal-title>
<issn pub-type="ppub">0026-461X</issn>
<publisher>
<publisher-name>Mineralogical Society</publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.1180/minmag.1978.042.324.06</article-id>
<title-group>
<article-title>Crystallization History of Sector-Zoned Microcline Megacrysts from the Godani Valley Pluton, Nigeria</article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname>Vaniman</surname>
<given-names>David</given-names>
</name>
<xref ref-type="author-notes" rid="FN1">1</xref>
<aff>Board of Earth Sciences, University of California, Santa Cruz, California 95064</aff></contrib></contrib-group>
<author-notes>
<fn fn-type="present-address" id="FN1"><label>1</label><p>Present address: Department of Earth and Space Sciences, State University of New York, Stony Brook, New York 11794.</p></fn></author-notes>
<pub-date pub-type="ppub">
<month>12</month>
<year>1978</year>
</pub-date>
<volume>42</volume>
<issue>324</issue>
<fpage>443</fpage>
<lpage>451</lpage>
<history>
<date date-type="received">
<day>12</day>
<month>8</month>
<year>1977</year>
</date>
<date date-type="rev-recd">
<day>23</day>
<month>5</month>
<year>1978</year>
</date></history>
<copyright-statement>Copyright &#x00A9; 1978, The Mineralogical Society</copyright-statement>
<copyright-year>1978</copyright-year>
<abstract>
<title>Summary</title>
<p>Sector-zoning is brought out by mineral inclusions (plagioclase, biotite, hornblende, sphene, and apatite) in 2 to 5 cm microcline megacrysts of the Godani Valley pluton, Nigeria. The inclusions are concentrated in the megacryst rims beneath the faces &#x007B;110&#x007D; and &#x007B;20<inline-formula><mml:math><mml:mrow><mml:mover><mml:mn>1</mml:mn><mml:mo>&#x00AF;</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula>&#x007D;; the megacryst cores are not sector-zoned. Comparison with other occurrences (Portugal and Czechoslovakia) shows that this type of sector-zoning is not controlled by growth rate. Chemical sector-zoning does not occur in the Godani megacrysts. Growth from magma is proposed, with preference for inclusions on faces at a high angle to the feldspar <italic>a</italic>-chain. A superficially similar type of sector-zoning occurs in microcline megacrysts of both pluton and wall rock at Papoose Flat, California, suggesting that this feature can be generated either by growth from magma or by replacement.</p></abstract>
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