{
"USGS Publications Warehouse": {
"@context": "https://schema.org",
"@type": "Article",
"additionalType": "Journal Article",
"name": "Disequilibrium dihedral angles in dolerite sills",
"identifier": [
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"value": "70118289",
"url": "https://pubs.usgs.gov/publication/70118289"
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"value": 70118289
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"propertyID": "DOI",
"value": "10.1130/G33119.1",
"url": "https://doi.org/10.1130/G33119.1"
}
],
"journal": {
"@type": "Periodical",
"name": "Geology",
"volumeNumber": "40",
"issueNumber": "9"
},
"inLanguage": "en",
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"name": "Geology"
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"datePublished": "2012",
"dateModified": "2014-07-28",
"abstract": "The geometry of clinopyroxene-plagioclase-plagioclase junctions in mafic rocks, measured by the median dihedral angle \u0398cpp, is created during solidification. In the solidifying Kilauea Iki (Hawaii) lava lake, the wider junctions between plagioclase grains are the first to be filled by pyroxene, followed by the narrower junctions. The final \u0398cpp, attained when all clinopyroxene-plagioclase-plagioclase junctions are formed, is 78\u00b0 in the upper crust of the lake, and 85\u00b0 in the lower solidification front. \u0398cpp in the 3.5-m-thick Traigh Bh\u00e0n na Sg\u00f9rra sill (Inner Hebrides) is everywhere 78\u00b0. In the Whin Sill (northern England, 38 m thick) and the Portal Peak sill (Antarctica, 129 m thick), \u0398cpp varies symmetrically, with the lowest values at the margins. The 266-m-thick Basement Sill (Antarctica) has asymmetric variation of \u0398cpp, attributed to a complex filling history. The chilled margins of the Basement Sill are partially texturally equilibrated, with high \u0398cpp. The plagioclase grain size in the two widest sills varies asymmetrically, with the coarsest rocks found in the upper third. Both \u0398cpp and average grain size are functions of model crystallization times. \u0398cpp increases from 78\u00b0 to a maximum of \u223c100\u00b0 as the crystallization time increases from 1 to 500 yr. Because the use of grain size as a measure of crystallization time is dependent on an estimate of crystal growth rates, dihedral angles provide a more direct proxy for cooling rates in dolerites.",
"description": "4 p.",
"publisher": {
"@type": "Organization",
"name": "Geological Society of America"
},
"author": [
{
"@type": "Person",
"name": "Richardson, Chris",
"givenName": "Chris",
"familyName": "Richardson"
},
{
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"name": "Holness, Marian B.",
"givenName": "Marian B.",
"familyName": "Holness"
},
{
"@type": "Person",
"name": "Helz, Rosalind T.",
"givenName": "Rosalind T.",
"familyName": "Helz",
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"value": "0000-0003-1550-0684",
"url": "https://orcid.org/0000-0003-1550-0684"
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