Reconstruction of the northeastern margin of the North China Craton: Paleomagnetic records from tectonic thermal events in Huinan of Jilin Province

The northeastern margin of North China Craton is located in an active area of tectonic movement. Paleomagnetic study can provide a basis record for tectonic evolution and magmatic thermal events. 246 samples were collected from 32 mining sites of the Middle Cambrian in Huinan area, Jilin Province, for petrology, rock magnetism and systematic thermal demagnetization experiments. Rock magnetic study implies that the main magnetic minerals of the Xuzhuang Formation sandy mudstone are hematite and magnetite. The main magnetic minerals of the Zhangxia Formation limestone are magnetite with smaller particles and a small amount of pyrite. Stepwise thermal demagnetization succeeded in isolating the middle-temperature characteristic directions of the samples. The average direction of the Xuzhuang Formation (D/I = 10.9°/50.8°, α₉₅ = 11.7°, corresponding pole position is 76°N, 264.6°E, A₉₅ = 13°), indicates that magmatic activity in the Early Cretaceous affected it. The average direction of the Zhangxia Formation (D/I = 29.1°/59.0°, α₉₅ = 6.5°, corresponding pole position is 68°N, 213.7°E, A₉₅ = 8.4°) were remagnetized which is related to Quaternary volcanic activity. Based on the analysis of regional geological background, at least two strong tectonic thermal events may have occurred from the Early Cretaceous to Quaternary respectively in Huinan area of Jilin Province, which also moved toward north large distance affected by Dunhua−Minshan sinistral slip fault during that time. These magnetic minerals were all remagnetizd and recorded a stable middle−temperature characteristic direction.