Assimilation of felsic crust by basaltic magma: Thermal limits and extents of crustal contamination of mantle-derived magmas

Research Article| June 01, 1995 Assimilation of felsic crust by basaltic magma: Thermal limits and extents of crustal contamination of mantle-derived magmas Peter W. Reiners; Peter W. Reiners 1Department of Geological Sciences, University of Washington, Seattle, Washington 98195 Search for other works by this author on: GSW Google Scholar Bruce K. Nelson; Bruce K. Nelson 1Department of Geological Sciences, University of Washington, Seattle, Washington 98195 Search for other works by this author on: GSW Google Scholar Mark S. Ghiorso Mark S. Ghiorso 1Department of Geological Sciences, University of Washington, Seattle, Washington 98195 Search for other works by this author on: GSW Google Scholar Author and Article Information Peter W. Reiners 1Department of Geological Sciences, University of Washington, Seattle, Washington 98195 Bruce K. Nelson 1Department of Geological Sciences, University of Washington, Seattle, Washington 98195 Mark S. Ghiorso 1Department of Geological Sciences, University of Washington, Seattle, Washington 98195 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1995) 23 (6): 563–566. https://doi.org/10.1130/0091-7613(1995)023<0563:AOFCBB>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Peter W. Reiners, Bruce K. Nelson, Mark S. Ghiorso; Assimilation of felsic crust by basaltic magma: Thermal limits and extents of crustal contamination of mantle-derived magmas. Geology 1995;; 23 (6): 563–566. doi: https://doi.org/10.1130/0091-7613(1995)023<0563:AOFCBB>2.3.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 SocietyGeology Search Advanced Search Abstract Basaltic magma is the most widely used probe of mantle chemistry and structure. Chemical characterization of the sources for mantle-derived magma is possible only after quantitative evaluation of possible contamination by crustal wall rocks. The most commonly invoked contamination mechanisms are the combined processes of crustal assimilation and magmatic fractional crystallization (AFC). Because of the energetic link between these processes, predicting assimilation and crystallization progress requires modeling both heat and mass transfer in the magma–country-rock system. Using the MELTS software package, we modeled isenthalpic (heat-balanced) AFC between two common types of basaltic magma and several types of felsic crust at 1 kbar. Our simulations show that during the early stages of isenthalpic AFC, the ratio of rates of assimilation to crystallization (r) may be substantially greater than one (2.0–2.7), allowing assimilation of a mass of country rock up to 5%–18% of the initial magma mass with only 3%–7% crystallization. The second stage of AFC, beginning with plagioclase and/or pyroxene saturation, is characterized by lower r (0.5–1.0). The initial high-r stage results from suppression of crystallization associated with the change in magma composition as assimilation progresses. Under certain conditions, even small degrees of crystallization of olivine alone, coupled with cooling of the magma, can accommodate relatively large amounts of crustal assimilation, and cause large shifts in isotopic and trace element geochemical indices with little differentiation. 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.