Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (19) Citing Articles via Google Scholar Google Scholar Articles by Aguirre-Díaz, G. J. Articles by Labarthe-Hernández, G. Search for Related Content GeoRef GeoRef Citation

Fissure ignimbrites: Fissure-source origin for voluminous ignimbrites of the Sierra Madre Occidental and its relationship with Basin and Range faulting

¹ Centro de Geociencias, Campus-Juriquilla, Universidad Nacional Autónoma de México, Querétaro, Qro. 76230, Mexico
² Instituto de Geología, Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico

The Sierra Madre Occidental is mostly composed of middle Tertiary large-volume ignimbrites. From the United States–Mexico border (31°N), the Sierra Madre Occidental extends southward to its intersection with the Mexican volcanic belt (21°N). Ignimbrites of equivalent age extend into southern Mexico as discontinuous outcrops. Considering the average thickness of 1000 m for these ignimbrites based on representative measured sections, a conservative estimate of their total volume is 393,000 km³. Fewer than 15 calderas have been identified in this province, and the source of most of these ignimbrites has been an unsolved problem. We present geologic evidence indicating that fissures, most of them with the regional trend of Basin and Range faults, served as conduits for the ignimbrites. These fissures can be several kilometers long and are represented by pyroclastic (ignimbrite) dikes, rhyolitic lava dikes, linearly aligned lava domes, and elongated coignimbrite lithic-lag breccias adjacent to Basin and Range faults. Considering that the Basin and Range extension overlapped in time and space with the ignimbrite flare-up, we propose a model in which batholith-sized magma chambers reached shallow crustal levels and erupted their contents when they reached Basin and Range normal faults. The faults acted as vents and caused fast decompression when the system was opened, and large volumes of silicic magmas were explosively erupted. Finally, devolatilized rhyolitic magmas were emplaced as domes or dikes. We propose the term "fissure ignimbrites" for ignimbrites formed in this way.

Key Words: ignimbrite • Basin and Range • pyroclastic dikes • Sierra Madre Occidental • Mexico

This article has been cited by other articles:

				C. Winter, C. Breitkreuz, and M. Lapp Textural analysis of a Late Palaeozoic coherent-pyroclastic rhyolitic dyke system near Burkersdorf (Erzgebirge, Saxony, Germany) Geological Society, London, Special Publications, January 1, 2008; 302(1): 199 - 221. [Abstract] [Full Text] [PDF]

				S. E. Bryan, L. Ferrari, P. W. Reiners, C. M. Allen, C. M. Petrone, A. Ramos-Rosique, and I. H. Campbell New Insights into Crustal Contributions to Large-volume Rhyolite Generation in the Mid-Tertiary Sierra Madre Occidental Province, Mexico, Revealed by U Pb Geochronology J. Petrology, January 1, 2008; 49(1): 47 - 77. [Abstract] [Full Text] [PDF]

				L. Ferrari, M. Valencia-Moreno, and S. Bryan Magmatism and tectonics of the Sierra Madre Occidental and its relation with the evolution of the western margin of North America Geological Society of America Special Papers, January 1, 2007; 422(0): 1 - 39. [Abstract] [Full Text] [PDF]

				G. Pe-Piper and D. J.W. Piper Neogene backarc volcanism of the Aegean: New insights into the relationship between magmatism and tectonics Geological Society of America Special Papers, January 1, 2007; 418(0): 17 - 31. [Abstract] [Full Text] [PDF]

				A. F. Nieto-Samaniego, S. A. Alaniz-Alvarez, and A. Camprubi Mesa Central of Mexico: Stratigraphy, structure, and Cenozoic tectonic evolution Geological Society of America Special Papers, January 1, 2007; 422(0): 41 - 70. [Abstract] [Full Text] [PDF]

				D.M. Gravley, C.J.N. Wilson, G.S. Leonard, and J.W. Cole Double trouble: Paired ignimbrite eruptions and collateral subsidence in the Taupo Volcanic Zone, New Zealand Geological Society of America Bulletin, January 1, 2007; 119(1-2): 18 - 30. [Abstract] [Full Text] [PDF]

				E. R. Swanson, K. A. Kempter, F. W. McDowell, and W. C. McIntosh Major ignimbrites and volcanic centers of the Copper Canyon area: A view into the core of Mexico's Sierra Madre Occidental Geosphere, May 1, 2006; 2(3): 125 - 141. [Abstract] [Full Text] [PDF]