Crustal Cross Sections from the Western North American Cordillera and Elsewhere: Implications for Tectonic and Petrologic Processes
Mesozoic magmatism in an upper- to middle-crustal section through the Cordilleran continental margin arc, eastern Transverse Ranges, California
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Published:January 01, 2009
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CiteCitation
Sarah K. Needy, J. Lawford Anderson, Joseph L. Wooden, R.J. Fleck, Andrew P. Barth, Scott R. Paterson, Valbone Memeti, Geoffrey S. Pignotta, 2009. "Mesozoic magmatism in an upper- to middle-crustal section through the Cordilleran continental margin arc, eastern Transverse Ranges, California", Crustal Cross Sections from the Western North American Cordillera and Elsewhere: Implications for Tectonic and Petrologic Processes, Robert B. Miller, Arthur W. Snoke
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The eastern Transverse Ranges provide essentially continuous exposure for >100 km across the strike of the Mesozoic Cordilleran orogen. Thermobarometric calculations based on hornblende and plagioclase compositions in Mesozoic plutonic rocks show that the first-order distribution of rock units resulted from differential Laramide exhumation. Mesozoic supracrustal rocks are preserved in the relatively little exhumed eastern part of the eastern Transverse Ranges and south-central Mojave Desert, and progressively greater rock uplift and exhumation toward the west exposed rocks originating at mid-crustal depths. The eastern Transverse Ranges thus constitute a tilted, nearly continuously exposed crustal section of the Mesozoic magmatic arc and framework rocks from subvolcanic levels to paleodepths as great as ~22 km. The base of this tilted arc section is a moderately east-dipping sheeted magmatic complex >10 km in width by 70 km in length, constructed structurally beneath, yet synchronous with Late Jurassic and Cretaceous upper-crustal plutons. Geochronology and regional structural relations thus suggest that arc magmas generated in the lower crust of this continental arc interacted in a complex mid-crustal zone of crystallization and mixing; products of this zone were parental magmas that formed relatively homogeneous upper crustal felsic plutons and fed lavas and voluminous ignimbrites.
- absolute age
- amphibole group
- California
- chain silicates
- clinoamphibole
- Cretaceous
- crust
- crystallization
- dates
- exhumation
- feldspar group
- felsic composition
- framework silicates
- hornblende
- igneous rocks
- ignimbrite
- intrusions
- ion probe data
- Jurassic
- magmas
- magmatism
- mass spectra
- Mesozoic
- metamorphic rocks
- mixing
- North America
- North American Cordillera
- P-T conditions
- plagioclase
- plutonic rocks
- plutons
- pyroclastics
- SHRIMP data
- silicates
- spectra
- supracrustals
- tilt
- Transverse Ranges
- U/Pb
- United States
- uplifts
- Upper Jurassic
- volcanic rocks
- Little San Bernardino Mountains
- Pinto Mountains
- Hexie Mountains