Abstract
Paleomagnetism of the southwestern U.S.A. recorded by 0–5 Ma igneous rocks
Scripps Institution of Oceanography, University of California, San Diego, California, USA
Scripps Institution of Oceanography, University of California, San Diego, California, USA
Scripps Institution of Oceanography, University of California, San Diego, California, USA
Scripps Institution of Oceanography, University of California, San Diego, California, USA
Scripps Institution of Oceanography, University of California, San Diego, California, USA
Scripps Institution of Oceanography, University of California, San Diego, California, USA
The issue of permanent nondipole contributions to the time-averaged field lies at the very heart of paleomagnetism and the
study of the ancient geomagnetic field. In this paper we focus on paleomagnetic directional results from igneous rocks of
the southwestern U.S.A. in the age range 0–5 Ma and investigate both the time-averaged field and its variability about the
mean value. Several decades of work in the southwestern United States have resulted in the publication of paleomagnetic data
from over 800 individual paleomagnetic sites. As part of a new investigation of the San Francisco Volcanics, we collected
paleomagnetic samples from 47 lava flows, many of which have been previously dated. The new data combined with published data
are highly scattered. Contributions to the scatter were considered, and we find that removal of data sets from tectonically
active areas and judicious selection according to
Received 8 March 2001; accepted 25 January 2003; published 11 April 2003.
Citation: (2003), Paleomagnetism of the southwestern U.S.A. recorded by 0–5 Ma igneous rocks, Geochem. Geophys. Geosyst., 4(4), 8802, doi:10.1029/2002GC000343.
Cited By
Brown, Laurie L. (2004), Paleomagnetism and 40Ar/39Ar Chronology of Lavas from Meseta del Lago Buenos Aires, Patagonia, Geochem Geophys Geosyst, 5, Q01H04, doi:10.1029/2003GC000526.
Johnson, C. L., C. G. Constable, L. Tauxe, R. Barendregt, L. L. Brown, R. S. Coe, P. Layer, V. Mejia, N. D. Opdyke, and B. S. Singer (2008), Recent investigations of the 0–5 Ma geomagnetic field recorded by lava flows, Geochem Geophys Geosyst, 9, Q04032, doi:10.1029/2007GC001696.
Lawrence, K. P., C. G. Constable, and C. L. Johnson (2006), Paleosecular variation and the average geomagnetic field at ±20° latitude, Geochem Geophys Geosyst, 7, Q07007, doi:10.1029/2005GC001181.
Mankinen, Edward A. (2008), Paleomagnetic study of late Miocene through Pleistocene igneous rocks from the southwestern USA: Results from the historic collections of the U.S. Geological Survey Menlo Park laboratory, Geochem Geophys Geosyst, 9, Q05017, doi:10.1029/2008GC001957.
Mejia, V. (2005), Paleosecular variation and time-averaged field recorded in late Pliocene–Holocene lava flows from Mexico, Geochem Geophys Geosyst, 6, Q07H19, doi:10.1029/2004GC000871.
Petronille, Marie (2005), Paleomagnetism of Ar-Ar dated lava flows from the Ceboruco-San Pedro volcanic field (western Mexico): Evidence for the Matuyama-Brunhes transition precursor and a fully reversed geomagnetic event in the Brunhes chron, J Geophys Res, 110, B08101, doi:10.1029/2004JB003321.
Stone, David B., and Paul W. Layer (2006), Paleosecular variation and GAD studies of 0–2 Ma flow sequences from the Aleutian Islands, Alaska, Geochem Geophys Geosyst, 7, Q04H22, doi:10.1029/2005GC001007.
Tauxe, Lisa (2004), Paleomagnetism and 40Ar/39Ar ages from volcanics extruded during the Matuyama and Brunhes Chrons near McMurdo Sound, Antarctica, Geochem Geophys Geosyst, 5, Q06H12, doi:10.1029/2003GC000656.
Tauxe, Lisa (2004), Paleomagnetic results from the Snake River Plain: Contribution to the time-averaged field global database, Geochem Geophys Geosyst, 5, Q08H13, doi:10.1029/2003GC000661.
