|
|
 |
|||||||||||||||||
|
|||||||||||||||||
 |
|||||||||||||||||
| JOURNAL HOME | HELP | CONTACT PUBLISHER | SUBSCRIBE | ARCHIVE | SEARCH | TABLE OF CONTENTS |
1 Centro de Geociencias, Universidad Nacional Autónoma de México, Campus Juriquilla, Apdo. Postal 1-742, C.P. 76001 Querétaro, Querétaro, Mexico
2 Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road NW, Washington, D.C. 20015, USA
3 Dipartimento di Scienze della Terra, Università degli Studi di Firenze, Via La Pira 4, I-50121 Firenze, Italy
Mantle plumes or decompression melting of a heterogeneous mantle have been proposed to explain oceanic-island basalt (OIB) type lavas found in the western Trans-Mexican volcanic belt. We show that mantle plumes cannot account for several geologic observations, whereas decompression melting is unrealistic given the low extension rate in the volcanic arc. On the basis of new geologic and geochemical studies, we propose an alternative model that reconciles geologic data, plate tectonic history, and petrology. Since 8.5 Ma, the volcanic front has migrated trenchward 
80 km, and OIB began to be emplaced in the rear half of the arc after a period of stalled subduction of the Rivera plate between 7.2 and 4.8 Ma. As a whole, OIB accounts for 5% of the total volume of volcanism. Their trace element signatures require an enriched-mantle source, akin to the deep asthenosphere, but also indicate a minor involvement of a subduction component. We propose that during the period of very low convergence at the end of the Miocene, the leading edge of the Rivera slab started to sink into the mantle and continued rolling back until it reached the present dip of 45°. The sinking of the slab may have induced small amounts of asthenosphere to flow laterally into the opening mantle wedge, from the Gulf of California rift on the west and through the subducted Rivera-Cocos plate boundary on the east. This mechanism would produce veins of relatively enriched mantle, which would be able to produce melts with an OIB composition once the flux of fluids released from the subducted slab resumed.
Key Words: Mexico • Rivera plate • Trans-Mexican volcanic belt • oceanic island basalts • slab rollback • asthenosphere
This article has been cited by other articles:
|
|
 |
|
  P. R. Castillo Origin of Nb-enriched basalts and adakites in Baja California, Mexico, revisited: Reply Geological Society of America Bulletin, September 1, 2009; 121(9-10): 1470 - 1472. [Full Text] [PDF]
|
|
|
|
 |
|
 G. F. Zellmer Petrogenesis of Sr-rich adakitic rocks at volcanic arcs: insights from global variations of eruptive style with plate convergence rates and surface heat flux Journal of the Geological Society, July 1, 2009; 166(4): 725 - 734. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. Vigouroux, P. J. Wallace, and A. J. R. Kent Volatiles in High-K Magmas from the Western Trans-Mexican Volcanic Belt: Evidence for Fluid Fluxing and Extreme Enrichment of the Mantle Wedge by Subduction Processes J. Petrology, September 1, 2008; 49(9): 1589 - 1618. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. R. Castillo Origin of the adakite-high-Nb basalt association and its implications for postsubduction magmatism in Baja California, Mexico Geological Society of America Bulletin, March 1, 2008; 120(3-4): 451 - 462. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Agostini, C. Doglioni, F. Innocenti, P. Manetti, S. Tonarini, and M. Y. Savascin The transition from subduction-related to intraplate Neogene magmatism in the Western Anatolia and Aegean area Geological Society of America Special Papers, January 1, 2007; 418(0): 1 - 15. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Gomez-Tuena, Ma. T. Orozco-Esquivel, and L. Ferrari Igneous petrogenesis of the Trans-Mexican Volcanic Belt Geological Society of America Special Papers, January 1, 2007; 422(0): 129 - 181. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. M. Petrone, L. Francalanci, L. Ferrari, P. Schaaf, and S. Conticelli The San Pedro-Cerro Grande volcanic complex (Nayarit, Mexico): Inferences on volcanology and magma evolution Geological Society of America Special Papers, January 1, 2006; 402(0): 65 - 98. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. Ferrari Slab detachment control on mafic volcanic pulse and mantle heterogeneity in central Mexico Geology, January 1, 2004; 32(1): 77 - 80. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
I. S. Torres-Alvarado, S. P. Verma, and F. Velasco-Tapia Generation of oceanic-island basalt-type volcanism in the western Trans-Mexican volcanic belt by slab rollback, asthenosphere infiltration, and variable flux melting: Comment and Reply: COMMENT Geology, September 1, 2002; 30(9): 857 - 858. [Full Text] [PDF]
|
|
|
|
|
|
L. Ferrari, C. M. Petrone, and L. Francalanci Reply Geology, September 1, 2002; 30(9): 858 - 859. [Full Text] [PDF]
|
|
| JOURNAL HOME | HELP | CONTACT PUBLISHER | SUBSCRIBE | ARCHIVE | SEARCH | TABLE OF CONTENTS |
