Geochemistry, Geophysics, Geosystems Geochem Geophys Geosyst 1525-2027 1525-2027 10 2013 14 10 10.1002/ggge.v14.10 https://agupubs.onlinelibrary.wiley.com/toc/15252027/14/10 Snapshot of the Matuyama‐Brunhes reversal process recorded in <sup>40</sup> Ar/ <sup>39</sup> Ar‐dated lavas from Guadeloupe, West Indies M. C. Brown Helmholtz‐Zentrum Potsdam Deutsches GeoForschungsZentrum Telegrafenberg 14473 Potsdam Germany B. R. Jicha Department of Geoscience University of Wisconsin‐Madison Madison Wisconsin USA B. S. Singer Department of Geoscience University of Wisconsin‐Madison Madison Wisconsin USA J. Shaw Geomagnetism Laboratory School of Environmental Sciences University of Liverpool Liverpool UK

We obtain new 40 Ar/ 39 Ar ages for three lavas that record part of the Matuyama‐Brunhes geomagnetic field reversal process on Guadeloupe. These lavas record a reversed‐transitional‐reversed magnetostratigraphy and yield a weighted mean isochron age of 785.2 ± 5.2 ka (2 σ analytical uncertainty) relative to an age for the Fish Canyon sanidine standard of 28.201 Ma. This age is of greater accuracy than ages obtained previously by K‐Ar dating. These lavas may record directional fluctuations occurring between the Matuyama‐Brunhes precursor and the final directional reversal. Such variations have been observed in some globally distributed coupled paleomagnetic and oxygen isotope marine sedimentary records of the Matuyama‐Brunhes reversal. Previous paleointensity estimates from these lavas indicate reduced, but fluctuating field strength during this time.

Key Points

New Ar/Ar dates from lavas on Guadeloupe island

Lavas record part of the Matuyama‐Brunhes geomagnetic reversal process

10 2013 10 2013 4341 4350 10.1002/ggge.20263 http://onlinelibrary.wiley.com/termsAndConditions#vor 10.1002/ggge.20263 https://agupubs.onlinelibrary.wiley.com/doi/10.1002/ggge.20263 https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/ggge.20263 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fggge.20263 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fggge.20263 10.1007/s11214-010-9695-2 10.1126/science.256.5055.356 10.1111/j.1365-246X.2006.03234.x 10.1016/j.pepi.2008.11.001 Paleomagnetism: Magnetic Domains to Geologic Terrains Butler R. F. 1992 10.1016/j.epsl.2011.07.026 10.1016/S0031-9201(99)00170-3 10.1029/1999JB900238 10.1098/rsta.2000.0572 10.1038/39570 10.1111/j.1365-246X.2004.02329.x 10.1029/2010GC003203 10.1016/S0009-2541(98)00049-7 10.1016/S0031-9201(99)00147-8 10.1038/nature02459 10.1029/145GM16 10.1098/rsta.2000.0578 10.1016/j.epsl.2004.03.003 10.1098/rspa.1953.0064 10.1029/1999JB900048 10.1016/j.pepi.2007.03.003 10.1016/0012-821X(95)00231-Z 10.1111/j.1365‐246X.2011.05086.x 10.1130/B30472.1 10.1139/e88-024 10.1126/science.1154339 10.1016/j.epsl.2006.10.025 10.1111/j.1365‐246X.2009.04264.x 10.1029/2004PA001071 10.1016/S0016-7037(99)00204-5 10.1029/2010JB008093 10.1046/j.1365-246x.2000.00130.x 10.1029/JB090iB12p10417 10.1029/95JB03740 10.1046/j.1365-246X.2002.01841.x 10.1016/S0012-821X(03)00053-0 10.1029/97PA01019 10.1016/j.quageo.2009.02.015 10.1016/j.gca.2011.06.021 10.1080/13658810601169899 10.1029/2002JB002124 10.1016/j.epsl.2011.09.017 10.1016/j.epsl.2007.03.030 10.1016/j.jvolgeores.2009.08.016 Radiogenic Isotope Geochronology in The Geologic Time Scale Schmitz M. D. 115 2012 10.1016/0012-821X(96)00003-9 10.1038/nature03431 10.1016/0012-821X(77)90060-7 10.1016/j.epsl.2010.05.031 10.1029/2003GC000635 10.1016/0012-821X(92)90114-B An Introduction to Error Analysis: The Study of Uncertainties in Physics Measurements Taylor J. R. 1997 10.1186/BF03352221 10.1016/0012-821X(89)90154-4 10.1029/1998JB900099 10.1029/98EO00426 10.1111/j.1365‐246X.2005.02665.x 10.1186/BF03351679