Anisotropy of magnetic susceptibility of Hannuoba basalt, northern China: Constraints on the vent position of the lava sequences

Anisotropy of magnetic susceptibility (AMS) was determined for Hannuoba basaltic samples from 17 flows (21.4 ± 0.7Ma) distributed in three sections (Jianshaba, Yuershan and Manjing) around Zhangbei, northern China. The results show normal ‘flow’ fabrics with horizontal foliation planes. The typical ratios of the principal AMS axes are 1.01 for the magnetic lineation (L) and 1.02 for the foliation (F), respectively. Magnetic hysteresis loop, isothermal remanence, thermomagnetic properties, and optical observations indicate that pseudo‐single domain (PSD) low‐titanium magnetite particles dominate the low‐field susceptibility of samples. Thus the AMS of the magma at this area is believed to be originated from the lineation of the low‐Titanium magnetite particles driven by the lava flow. Since the Kmax trends coincide well with the observed flow directions, the intersection of the mean Kmax trends from these three sites perfectly defines the previously known vent position of the lava sequences.