Depths and temperatures of <10.5 Ma mantle melting and the lithosphere-asthenosphere boundary below southern Oregon and northern California
Plagioclase and spinel lherzolite thermometry and barometry are applied to an extensive geochemical dataset of young (<10.5 Ma) primitive basaltic lavas from across Oregon's High Lava Plains, California's Modoc Plateau, and the central-southern Cascades volcanic arc to calculate the dep...
| Main Authors: | , , , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
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American Geophysical Union (AGU)
2014
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| Online Access: | http://hdl.handle.net/1721.1/85581 https://orcid.org/0000-0003-3136-4942 |
| _version_ | 1811081551138521088 |
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| author | Till, Christy B. Grove, Timothy L. Carlson, Richard W. Donnelly-Nolan, Julie M. Fouch, Matthew J. Wagner, Lara S. Hart, William K. |
| author2 | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
| author_facet | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Till, Christy B. Grove, Timothy L. Carlson, Richard W. Donnelly-Nolan, Julie M. Fouch, Matthew J. Wagner, Lara S. Hart, William K. |
| author_sort | Till, Christy B. |
| collection | MIT |
| description | Plagioclase and spinel lherzolite thermometry and barometry are applied to an extensive geochemical dataset of young (<10.5 Ma) primitive basaltic lavas from across Oregon's High Lava Plains, California's Modoc Plateau, and the central-southern Cascades volcanic arc to calculate the depths and temperatures of mantle melting. This study focuses on basalts with low pre-eruptive H2O contents that are little fractionated near-primary melts of mantle peridotite (i.e., basalts thought to be products of anhydrous decompression mantle melting). Calculated minimum depths of nominally anhydrous melt extraction are 40–58 km below Oregon's High Lava Plains, 41–51 km below the Modoc Plateau, and 37–60 km below the central and southern Cascades arc. The calculated depths are very close to Moho depths as determined from a number of regional geophysical studies and suggest that the geophysical Moho and lithosphere-asthenosphere boundary in this region are located in very close proximity to one another (within 5–10 km). The basalts originated at 1185–1383°C and point to a generally warm mantle beneath this area but not one hot enough to obviously require a plume contribution. Our results, combined with a range of other geologic, geophysical, and geochemical constraints, are consistent with a regional model whereby anhydrous mantle melting over the last 10.5 Ma in a modern convergent margin and back arc was driven by subduction-induced corner flow in the mantle wedge, and to a lesser extent, toroidal flow around the southern edge of the subducting Juan de Fuca and Gorda plates, and crustal extension-related upwelling of the shallow mantle. |
| first_indexed | 2024-09-23T11:48:20Z |
| format | Article |
| id | mit-1721.1/85581 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T11:48:20Z |
| publishDate | 2014 |
| publisher | American Geophysical Union (AGU) |
| record_format | dspace |
| spelling | mit-1721.1/855812022-10-01T06:08:35Z Depths and temperatures of <10.5 Ma mantle melting and the lithosphere-asthenosphere boundary below southern Oregon and northern California Till, Christy B. Grove, Timothy L. Carlson, Richard W. Donnelly-Nolan, Julie M. Fouch, Matthew J. Wagner, Lara S. Hart, William K. Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Till, Christy B. Grove, Timothy L. Plagioclase and spinel lherzolite thermometry and barometry are applied to an extensive geochemical dataset of young (<10.5 Ma) primitive basaltic lavas from across Oregon's High Lava Plains, California's Modoc Plateau, and the central-southern Cascades volcanic arc to calculate the depths and temperatures of mantle melting. This study focuses on basalts with low pre-eruptive H2O contents that are little fractionated near-primary melts of mantle peridotite (i.e., basalts thought to be products of anhydrous decompression mantle melting). Calculated minimum depths of nominally anhydrous melt extraction are 40–58 km below Oregon's High Lava Plains, 41–51 km below the Modoc Plateau, and 37–60 km below the central and southern Cascades arc. The calculated depths are very close to Moho depths as determined from a number of regional geophysical studies and suggest that the geophysical Moho and lithosphere-asthenosphere boundary in this region are located in very close proximity to one another (within 5–10 km). The basalts originated at 1185–1383°C and point to a generally warm mantle beneath this area but not one hot enough to obviously require a plume contribution. Our results, combined with a range of other geologic, geophysical, and geochemical constraints, are consistent with a regional model whereby anhydrous mantle melting over the last 10.5 Ma in a modern convergent margin and back arc was driven by subduction-induced corner flow in the mantle wedge, and to a lesser extent, toroidal flow around the southern edge of the subducting Juan de Fuca and Gorda plates, and crustal extension-related upwelling of the shallow mantle. 2014-03-10T17:34:03Z 2014-03-10T17:34:03Z 2013-04 2013-01 Article http://purl.org/eprint/type/JournalArticle 15252027 http://hdl.handle.net/1721.1/85581 Till, Christy B., Timothy L. Grove, Richard W. Carlson, Julie M. Donnelly-Nolan, Matthew J. Fouch, Lara S. Wagner, and William K. Hart. “Depths and Temperatures of <10.5 Ma Mantle Melting and the Lithosphere-Asthenosphere Boundary Below Southern Oregon and Northern California.” Geochem. Geophys. Geosyst. (April 2013): 1–16. Copyright © 2013 American Geophysical Union https://orcid.org/0000-0003-3136-4942 en_US http://dx.doi.org/10.1002/ggge.20070 Geochemistry, Geophysics, Geosystems Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Geophysical Union (AGU) Other univ. web domain |
| spellingShingle | Till, Christy B. Grove, Timothy L. Carlson, Richard W. Donnelly-Nolan, Julie M. Fouch, Matthew J. Wagner, Lara S. Hart, William K. Depths and temperatures of <10.5 Ma mantle melting and the lithosphere-asthenosphere boundary below southern Oregon and northern California |
| title | Depths and temperatures of <10.5 Ma mantle melting and the lithosphere-asthenosphere boundary below southern Oregon and northern California |
| title_full | Depths and temperatures of <10.5 Ma mantle melting and the lithosphere-asthenosphere boundary below southern Oregon and northern California |
| title_fullStr | Depths and temperatures of <10.5 Ma mantle melting and the lithosphere-asthenosphere boundary below southern Oregon and northern California |
| title_full_unstemmed | Depths and temperatures of <10.5 Ma mantle melting and the lithosphere-asthenosphere boundary below southern Oregon and northern California |
| title_short | Depths and temperatures of <10.5 Ma mantle melting and the lithosphere-asthenosphere boundary below southern Oregon and northern California |
| title_sort | depths and temperatures of 10 5 ma mantle melting and the lithosphere asthenosphere boundary below southern oregon and northern california |
| url | http://hdl.handle.net/1721.1/85581 https://orcid.org/0000-0003-3136-4942 |
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