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Rhyolite-basalt complex on Gardiner River, Yellowstone Park, Wyoming

1944; Geological Society of America; Volume: 55; Issue: 9 Linguagem: Inglês

10.1130/gsab-55-1047

1943-2674

Ray E. Wilcox,

Isotope Analysis in Ecology

Research Article| September 01, 1944 Rhyolite-basalt complex on Gardiner River, Yellowstone Park, Wyoming RAY E. WILCOX RAY E. WILCOX Search for other works by this author on: GSW Google Scholar Author and Article Information RAY E. WILCOX Publisher: Geological Society of America Received: 07 Aug 1943 First Online: 02 Mar 2017 Online Issn: 1943-2674 Print Issn: 0016-7606 © 1944 Geological Society of America GSA Bulletin (1944) 55 (9): 1047–1080. https://doi.org/10.1130/GSAB-55-1047 Article history Received: 07 Aug 1943 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation RAY E. WILCOX; Rhyolite-basalt complex on Gardiner River, Yellowstone Park, Wyoming. GSA Bulletin 1944;; 55 (9): 1047–1080. doi: https://doi.org/10.1130/GSAB-55-1047 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Certain lavas on Gardiner River in Yellowstone Park, Wyoming, have been cited (Iddings, 1899, p. 430; Fenner, 1934; 1937; 1938) as representing extensive assimilation of solid basaltic material by molten rhyolitic lava at pressures near that of the atmosphere. The writer, however, concludes that the features of the Gardiner River lavas resulted from the mixing of nearly contemporaneous rhyolitic and basaltic lavas. On this basis, the occurrence does not bear on the question of the relative importance of assimilation versus gravitational differentiation in the origin of rocks.The proponents of assimilation base their case on the definite intrusive relationships of the rhyolite into the basalt (Iddings, 1899, p. 430–32; Fenner, 1938), the roughly V-shaped form of the rhyolite-basalt contact, and the chemical gradation from rhyolite to basalt (Fenner, 1938). However, the writer concludes that, if the two lavas had been erupted simultaneously, the solidifying effect of the normally cooler rhyolitic lava on the basaltic lava would have caused the same relationships.Two important features point strongly to an origin of the Gardiner River lavas by mixing of molten rhyolitic and basaltic lavas: (1) A chill phase of the rhyolite against country rock but not against the basalt indicates that the basalt was not cold when contacted by the rhyolitic lava. (2) The presence of quartz and orthoclase xenocrysts (originally phenocrysts of the rhyolitic magma) within the basalt several yards from the contact indicates that the basalt was liquid or mushy when contacted by the rhyolitic lava. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.