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Petrology and petrogenesis of the Bokan Granite Complex, southeastern Alaska

1982; Geological Society of America; Volume: 93; Issue: 9 Linguagem: Inglês

10.1130/0016-7606(1982)93 2.0.co;2

1943-2674

Tommy B. Thompson, John R. Pierson, Thomas Lyttle,

Geochemistry and Geologic Mapping

Research Article| September 01, 1982 Petrology and petrogenesis of the Bokan Granite Complex, southeastern Alaska TOMMY B. THOMPSON; TOMMY B. THOMPSON 1Department of Earth Resources, Colorado State University, Fort Collins, Colorado 80523 Search for other works by this author on: GSW Google Scholar JOHN R. PIERSON; JOHN R. PIERSON 1Department of Earth Resources, Colorado State University, Fort Collins, Colorado 80523 Search for other works by this author on: GSW Google Scholar THOMAS LYTTLE THOMAS LYTTLE 1Department of Earth Resources, Colorado State University, Fort Collins, Colorado 80523 Search for other works by this author on: GSW Google Scholar Author and Article Information TOMMY B. THOMPSON 1Department of Earth Resources, Colorado State University, Fort Collins, Colorado 80523 JOHN R. PIERSON 1Department of Earth Resources, Colorado State University, Fort Collins, Colorado 80523 THOMAS LYTTLE 1Department of Earth Resources, Colorado State University, Fort Collins, Colorado 80523 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1982) 93 (9): 898–908. https://doi.org/10.1130/0016-7606(1982)93 2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation TOMMY B. THOMPSON, JOHN R. PIERSON, THOMAS LYTTLE; Petrology and petrogenesis of the Bokan Granite Complex, southeastern Alaska. GSA Bulletin 1982;; 93 (9): 898–908. doi: https://doi.org/10.1130/0016-7606(1982)93 2.0.CO;2 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 The Bokan Granite Complex is a peralka-line ring-dike complex emplaced into marine shales, volcanic flows and tuffs, and plutonic rocks. Mineralogically and chemically, the Complex is composed of I-type granites. Aegirine- and riebeckite-bearing granite aplites, porphyries, and pegmatites comprise twelve distinct intrusive episodes. The aegirine-bearing rocks occur in an outer annular zone formed during early crystallization. Subsequent rocks are riebeckite-bearing, due to devolatilization of the magma chamber during a collapse-ring-dike emplacement event. Early crystallization of alkali feldspar occurred during magma ascension from a lower crustal-upper mantle source. At shallow depths, subsolvus crystallization allowed microcline and albite to dominate. Local bodies of aegirine syenite were formed during the early collapse-ring-dike emplacement, in response to the magma devolatilization. The riebeckite granites reflect lower Po2 and possibly declining peralkalinity.The granitic rocks at Bokan all exhibit Na2O contents greater than K2O. Lithophile elements are concentrated in all the rocks, especially in zones where hydrothermal albite and chlorite formed. Rb/Sr ratios increase in progressively younger rocks in the Complex. Agpaitic ratios vary from 0.92 to 2.08 for the granitic rocks. 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.