Abstract
Emplacement of a series of late Jurassic to early Cretaceous tonalites and diorites at depths of 4 to 9 km accompanied volcanic arc construction in the Foothills terrane, central Sierra Nevada, California. Emplacement of these plutons occurred after initiation of faulting and rigid-rotation of bedding and immediately before widespread cleavage development. Pluton emplacement occurred by permissive emplacement in the hinges of large anticlines or domes, or as structurally controlled sill-like bodies in a ductile shear zone and was accompanied by widespread mingling of magmas. Subsequent deformation rotated but did not internally deform one pluton, strongly deformed several others and shortened the overlying volcanic and sedimentary sequences by 30 to 50%. We suggest that deformation was active throughout volcanic arc construction, but evolved from early more "brittle" deformation to ductile flow immediately after pluton emplacement and back to brittle deformation as the arc was uplifted and cooled. At this location, arc magmatism lasted at least 30 Ma whereas deformation lasted at least 35 Ma and possibly much longer. The different emplacement mechanisms, changing style of deformation and differences in viscosity contrast between plutons and wall rocks resulted in an impressive variety of structural characteristics and apparent timing relationships for the subvolcanic plutons.
Original language | English |
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Pages (from-to) | 89-110 |
Number of pages | 22 |
Journal | Tectonophysics |
Volume | 191 |
Issue number | 1-2 |
DOIs | |
Publication status | Published - 20 May 1991 |