Gauss-Matuyama polarity transition obtained from a loess section at Weinan, North-Central China

A record of Gauss-Matuyama (G/M) geomagnetic polarity transition has been o btained from a loess section at Weinan. Shaanxi Province in China. Grain si ze and weathering intensity analysis demonstrate a rather weak pedogenesis in the oldest loess unit L33 was deposited. Rock-and paleo-magnetic investi gations indicate that the remanent magnetization is mainly carried by magne tite and maghemite deposited as detrital grains. The record of the polarity transition based on ChRM directions of the low coercivity magnetic phase c omprises 33 transitional directions. A pre-transitional excursion defined b y 4 intermediate directions and lasting about 2.2 +/- 0.13 ka appears to ha ve occurred prior to the G/M polarity transition. Then, the record displays a N-S-N cycle with VGPs locating principally on American and Eastern-Asia longitudes. Finally, the reverse polarity is established with VGPs clusteri ng in the Atlantic near southern Africa. The total duration of the directio nal change for the G/M transitions at Weinan, as derived from independent l oess accumulation ratios, is about 9.43 +/- 0.64. During the G-M polarity t ransition, the decrease in field intensity occurs.