Continental rupture and the creation of new crust in the Salton Trough rift, Southern California and northern Mexico: Results from the Salton Seismic Imaging Project. Issue 10 (30th October 2016)

• Record Type: Journal Article
• Authors: Han, Liang; Hole, John A.; Stock, Joann M.; Fuis, Gary S.; Kell, Annie; Driscoll, Neal W.; Kent, Graham M.; Harding, Alistair J.; Rymer, Michael J.; González‐Fernández, Antonio; Lázaro‐Mancilla, Octavio
• Is Part Of: Journal of geophysical research. Volume 121:Issue 10(2016:Oct.)
• Page Start: 7469
• Page End: 7489
• Publication Date: 2016-10-30
• Subjects: active rifting -- continental rifting -- crustal structure -- Salton Trough -- controlled source seismic -- seismic velocity; Geomagnetism -- Periodicals; Geochemistry -- Periodicals; Geophysics -- Periodicals; Earth sciences -- Periodicals; 551.1
• DOI: 10.1002/2016JB013139
• Languages: English
• ISSNs: 2169-9313

Abstract

Abstract: A refraction and wide‐angle reflection seismic profile along the axis of the Salton Trough, California and Mexico, was analyzed to constrain crustal and upper mantle seismic velocity structure during active continental rifting. From the northern Salton Sea to the southern Imperial Valley, the crust is 17–18 km thick and approximately one‐dimensional. The transition at depth from Colorado River sediment to underlying crystalline rock is gradual and is not a depositional surface. The crystalline rock from ~3 to ~8 km depth is interpreted as sediment metamorphosed by high heat flow. Deeper felsic crystalline rock could be stretched preexisting crust or higher‐grade metamorphosed sediment. The lower crust below ~12 km depth is interpreted to be gabbro emplaced by rift‐related magmatic intrusion by underplating. Low upper mantle velocity indicates high temperature and partial melting. Under the Coachella Valley, sediment thins to the north and the underlying crystalline rock is interpreted as granitic basement. Mafic rock does not exist at 12–18 km depth as it does to the south, and a weak reflection suggests Moho at ~28 km depth. Structure in adjacent Mexico has slower midcrustal velocity, and rocks with mantle velocity must be much deeper than in the Imperial Valley. Slower velocity and thicker crust in the Coachella and Mexicali valleys define the rift zone between them to be >100 km wide in the direction of plate motion. North American lithosphere in the central Salton Trough has been rifted apart and is being replaced by new crust created by magmatism, sedimentation, and metamorphism. Key Points: Seismic refraction and reflection data constrain crustal and upper mantle structure of the Salton Trough Actively extending crust is 17–18 km thick and roughly one‐dimensional for >100 km in the plate motion direction North American lithosphere in the central Salton Trough has been rifted apart and is being replaced by new crust