Paleomagnetic analysed of two sediment cores off Cape Ghir

Holocene records documenting variations in direction and intensity of the geomagnetic field during the last about seven and a half millennia are presented for Northwest Africa. High resolution paleomagnetic analyses of two marine sediment sequences recovered from around 900 meter water depth on the upper continental slope off Cape Ghir (30°51'N, 10°16'W) were supplemented by magnetic measurements characterizing composition, concentration, grain size and coercivity of the magnetic mineral assemblage. Age control for the high sedimentation rate deposits (~60 cm/kyr) was established by AMS radiocarbon dates. The natural remanent magnetization (NRM) is very predominantly carried by a fine grained, mostly single domain (titano-)magnetite fraction allowing the reliable definition of stable NRM inclinations and declinations from alternating field demagnetization and principal component analysis. […]

本数据集呈现了约七千五百年间，西北非地区地磁场方向与强度变化的Holocene时期记录。通过对位于开普吉尔（北纬30°51'，西经10°16'）上大陆坡约900米水深处提取的两条海洋沉积序列进行高分辨率古地磁分析，并辅以表征磁性矿物组合成分、浓度、粒度和矫顽力的磁测量，以补充相关数据。通过AMS放射性碳测年法对高沉积速率沉积物（约每千年60厘米）进行年代控制。自然剩余磁化（NRM）主要被细粒度、多数为单畴（钛磁铁矿）的磁铁矿组分所携带，这使得从交变场退磁和主成分分析中可靠地定义稳定的NRM倾角和偏角成为可能。