Item talk:Q274030

{

 "USGS Publications Warehouse": {
   "@context": "https://schema.org",
   "@type": "Article",
   "additionalType": "Journal Article",
   "name": "A Coast Mountains provenance for the Valdez and Orca groups, southern Alaska, based on Nd, Sr, and Pb isotopic evidence",
   "identifier": [
     {
       "@type": "PropertyValue",
       "propertyID": "USGS Publications Warehouse IndexID",
       "value": "70018220",
       "url": "https://pubs.usgs.gov/publication/70018220"
     },
     {
       "@type": "PropertyValue",
       "propertyID": "USGS Publications Warehouse Internal ID",
       "value": 70018220
     },
     {
       "@type": "PropertyValue",
       "propertyID": "DOI",
       "value": "10.1016/0012-821X(93)90042-8",
       "url": "https://doi.org/10.1016/0012-821X(93)90042-8"
     },
     {
       "@type": "PropertyValue",
       "propertyID": "ISSN",
       "value": "0012821X"
     }
   ],
   "journal": {
     "@type": "Periodical",
     "name": "Earth and Planetary Science Letters",
     "volumeNumber": "116",
     "issueNumber": "1-4"
   },
   "inLanguage": "en",
   "isPartOf": [
     {
       "@type": "CreativeWorkSeries",
       "name": "Earth and Planetary Science Letters"
     }
   ],
   "datePublished": "1993",
   "dateModified": "2023-12-09",
   "abstract": "Nd, Sr, and Pb isotopic data were obtained for fourteen fine- to coarse-grained samples of accreted flysch of the Late Cretaceous and early Tertiary Valdez and Orca Groups in southern Alaska to determine the flysch provenance. Argillites and greywackes from the Orca Group, as well as compositionally similar but higher metamorphic grade rocks from the Valdez Group, show a restricted range of correlated\u00a0\u03b5Nd\u00a0( \u22120.6 to \u22123.8) and\u00a087Sr/86Sr (0.7060\u20130.7080) at the time of sediment deposition ( \u223c 50 Ma). Pb isotopic compositions also vary over a narrow range (\u00a0206Pb/204Pb= 19.138\u201319.395,\u00a0207Pb/204Pb= 15.593\u201315.703,\u00a0208Pb/204Pb= 38.677\u201339.209), and in the Orca Group the samples generally become more radiogenic with decreasing\u00a0\u03b5Nd\u00a0and increasing\u00a087Sr/86Sr. All samples have similar trace element compositions characterized by moderate light rare earth element enrichments, and low ratios of high field strength elements to large ion lithophile elements. Based on petrographic, geochemical, and isotopic data the sedimentary rocks are interpreted to have been derived largely from a Phanerozoic continental margin arc complex characterized by igneous rocks with\u00a0\u03b5Nd\u00a0values between 0 and \u22125. The latter conclusion is supported by the\u00a0\u03b5Nd\u00a0values of a tonalite clast and a rhyodacite clast in the Orca Group (\u03b5Nd\u00a0= \u22124.9and\u22120.9, respectively). However, trondjemitic clasts in the Orca Group have significantly lower\u00a0\u03b5Nd\u00a0( \u223c \u221210) and require a derivation of a portion of the flysch from Precambrian crustal sources. The Nd, Sr, and Pb isotopic compositions of both the Valdez and Orca Groups overlap the values determined for intrusive igneous rocks exposed within the northern portion of the Late Cretaceous to early Tertiary Coast Mountains Plutonic Complex in western British Columbia and equivalent rocks in southeastern Alaska. The isotopic data support previous conclusions based on geologic studies which suggest that the flysch was shed from this portion of the batholith, and from overlying continental margin arc-related volcanic rocks, following its rapid uplift in the Late Cretaceous and early Tertiary. The Precambrian crustal material present in the flysch may have been derived from Late Proterozoic or older metasedimentary and metaigneous rocks now exposed along the western margin of the Coast Mountains Plutonic Complex.",
   "description": "13 p.",
   "publisher": {
     "@type": "Organization",
     "name": "Elsevier"
   },
   "author": [
     {
       "@type": "Person",
       "name": "Plafker, G.",
       "givenName": "G.",
       "familyName": "Plafker",
       "identifier": {
         "@type": "PropertyValue",
         "propertyID": "ORCID",
         "value": "0000-0003-3972-0390",
         "url": "https://orcid.org/0000-0003-3972-0390"
       }
     },
     {
       "@type": "Person",
       "name": "Farmer, G. L.",
       "givenName": "G. L.",
       "familyName": "Farmer"
     },
     {
       "@type": "Person",
       "name": "Ayuso, R.",
       "givenName": "R.",
       "familyName": "Ayuso"
     }
   ]
 }

}