A detailed paleomagnetic and rock-magnetic investigation of the Matuyama-Brunhes geomagnetic reversal recorded in the tephra-paleosol sequence of Tlaxcala (Central Mexico)

摘要: Geomagnetic reversals are global phenomena, for about 50 years the paleomagnetists attempted to acquire as many detailed records possible using magnetic memory of sediments and lava flows. Yet, transitional field behavior remains poorly characterized largely because sporadic aspect volcanic eruptions. In some specific cases, paleosols such those developed from alluvial or aeolian sediments, may also record variations Field across polarity changes. Here, we report a paleomagnetic rock-magnetic investigation on radiometrically dated chromic luvisols located in Central Mexico carrying detrital chemical remanent magnetization. The research was order i) demonstrate primary origin remanence ii) show that paleosoils good candidates provide high resolution geomagnetic during reversals. lower part paleosoil sequence shows clearly defined reverse magnetization followed by geomagnetically unstable ended normal remanence. Our AMS rock data suggest is acquired initial stage soil formation context active activity since fabric essentially sedimentary paleodirections almost antipodal. Titanomagnetites identified main carriers measurements including thermomagnetics hysteresis cycles. We propose transition recorded this study correspond B-M boundary, considering K-Ar datings available at bottom potentially recorders paleosecular variation. identification boundary within studied has fundamental significance improving chronological scale Tlaxcala paleosol-sedimentary its correlation with proxies.