PERMO-TRIASSIC MAGNETOSTRATIGRAPHY IN WULONG AREA, SICHUAN, CHINA

The Permo-Triassic boundary in Wulong area, Sichuan Province, South China lies in a continuous marine carbonate succession with abundant fossil records. Two well-exposed sections were sampled for magnetostratigraphic studies. The experimental results of rock magnetism reveal that the samples from the Triassic limestones contain only magnetites among which 70% are multi-domain. The ChRM direction is carried by remaining 30% of single-domain magnetite. The Permian limestone samples are dominated by single-domain to superparamagnetic magnetites with little ChRM direction due to their fine-grained texture. Nevertheless, the polarity determination is still possible based on the NRM vector changes during thermal demagnetization. A Permo-Triassic polarity profile in Wulong area is established in the paper, and a tentative correlation with other known profiles is pursued. The authors suggest that the Illawarra reversal starts at the upper part of Wujiapingian, while some normal polarity events may exist in the Kiaman Epoch.