Mid-Cenozoic Caetano Tuff, Nevada: Tectonic and correlation implications from paleomagnetic data and sanidine 40Ar/39Ar dating
Abstract
Paleomagnetic results at more than 50 sites in strata mapped as Caetano Tuff in central Nevada reveal characteristic magnetizations with reverse polarity, up to the SE. The site-mean Caetano Tuff paleomagnetic pole (168.7°E, 68.6°N, A95=4.4°, n=44), differs from a reference pole for North America (BC02) by 15±6°. This implies a regional counterclockwise rotation of the sampling region of 9° to 21° relative to cratonic North America. The inferred rotation is estimated to have occurred in the interval 34 to 10 Ma, associated with regional Basin and Range rifting. Twelve new 40Ar/39Ar ages from Caetano ash-flow tuffs and associated rocks, combined with previously published 40Ar/39Ar ages, indicate an age of about 33.76 Ma for the Caetano Tuff. Jointly, the age and polarity information indicate that the eruptions of the Caetano Tuff occurred near the younger limit of polarity chron C13r. Relative to the International Commission of Stratigraphy timescale 2008, the Caetano Tuff is earliest Oligocene. However, relative to recent astronomically tuned geomagnetic polarity timescale chron boundaries, it is latest Eocene.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFMGP11A0761M
- Keywords:
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- 1525 GEOMAGNETISM AND PALEOMAGNETISM / Paleomagnetism applied to tectonics: regional;
- global;
- 1535 GEOMAGNETISM AND PALEOMAGNETISM / Reversals: process;
- timescale;
- magnetostratigraphy;
- 1599 GEOMAGNETISM AND PALEOMAGNETISM / General or miscellaneous