|
|
|
|||||||||||||||||
| JOURNAL HOME | HELP | CONTACT PUBLISHER | SUBSCRIBE | ARCHIVE | SEARCH | TABLE OF CONTENTS |
1 Department of Earth Sciences, Boston University, 685 Commonwealth Avenue, Boston, Massachusetts 02215
2 Department of Geology, CB 3315 Mitchell Hall, University of North Carolina, Chapel Hill, North Carolina 27599
3 White Mountain Research Station, 3000 East Line Street, Bishop, California 93514
4 Department of Geology and Geophysics, 717 WBB, University of Utah, Salt Lake City, Utah 84112
Field relationships and new U-Pb geochronology reveal that a significant number of dikes associated with the Independence dike swarm, both within the type locality and elsewhere, are of Cretaceous age. A new U-Pb zircon age for a diorite dike in the type locality of the Independence dike swarm in California confirms that some mafic dikes in the swarm are coeval with previously dated Late Jurassic felsic dikes. Cretaceous dikes in the eastern Sierra Nevada batholith are located nearand may be genetically related tocoeval mafic and felsic plutons. However, the presence of Cretaceous dikes throughout the swarm demonstrates that this is not a local phenomenon, and caution therefore should be exercised when using Independence-like dikes as temporal markers. We have not identified any consistent petrographic or chemical criteria that distinguish Jurassic Independence dikes from Cretaceous dikes. However, Jurassic dikes in the Sierra Nevada commonly contain a sinistral shear fabric that is absent in both dated Cretaceous dikes and undated dikes that intrude dated Cretaceous plutons. Despite intruding at least 60 m.y. apart, the orientations and petrology of the Jurassic and Cretaceous dikes are remarkably similar. Because dikes were intruded over a time period characterized by large changes in the orientation of plate convergence west of the Sierran arc, it is unlikely that the uniform structural orientation of Jurassic and Cretaceous dikes resulted from regional stresses imposed by the subducting plate. Instead, the orientation of Jurassic and Cretaceous dikes (and of many Sierran Cretaceous plutons) may have been controlled by preexisting faults or by the orientation of the continental margin.
Key Words: California Sierra Nevada batholith dike swarm geochronology tectonics
This article has been cited by other articles:
![]() |
K. L. Frankel, A. F. Glazner, E. Kirby, F. C. Monastero, M. D. Strane, M. E. Oskin, J. R. Unruh, J. D. Walker, S. Anandakrishnan, J. M. Bartley, et al. Active tectonics of the eastern California shear zone Field Guides, January 1, 2008; 11(0): 43 - 81. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. M. Bartley, A. F. Glazner, D. S. Coleman, A. Kylander-Clark, R. Mapes, and A. M. Friedrich Large Laramide dextral offset across Owens Valley, California, and its possible relation to tectonic unroofing of the southern Sierra Nevada Geological Society of America Special Papers, January 1, 2007; 434(0): 129 - 148. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. L. Barbeau Jr., M. N. Ducea, G. E. Gehrels, S. Kidder, P. H. Wetmore, and J. B. Saleeby U-Pb detrital-zircon geochronology of northern Salinian basement and cover rocks Geological Society of America Bulletin, March 1, 2005; 117(3-4): 466 - 481. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. H. Mahan, J. M. Bartley, D. S. Coleman, A. F. Glazner, and B. S. Carl Sheeted intrusion of the synkinematic McDoogle pluton, Sierra Nevada, California Geological Society of America Bulletin, December 1, 2003; 115(12): 1570 - 1582. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. S. Coleman, S. Briggs, A. F. Glazner, and C.J. Northrup Timing of plutonism and deformation in the White Mountains of eastern California Geological Society of America Bulletin, January 1, 2003; 115(1): 48 - 57. [Abstract] [Full Text] [PDF] |
||||
![]() |
O. T. Tobisch, O. T. Tobisch, R. S. Fiske, J. B. Saleeby, E. Holt, and S. S. Sorensen Steep tilting of metavolcanic rocks by multiple mechanisms, central Sierra Nevada, California Geological Society of America Bulletin, July 1, 2000; 112(7): 1043 - 1058. [Abstract] [Full Text] [PDF] |
||||
| JOURNAL HOME | HELP | CONTACT PUBLISHER | SUBSCRIBE | ARCHIVE | SEARCH | TABLE OF CONTENTS |