How Did South China Connect to and Separate From Gondwana? New Paleomagnetic Constraints From the Middle Devonian Red Beds in South China

• Published in: Geophysical research letters 2019-07, Vol.46 (13), p.7371-7378
• Main Authors: Xian, Hanbiao, Zhang, Shihong, Li, Haiyan, Xiao, Qisheng, Chang, Linxi, Yang, Tianshui, Wu, Huaichun
• Format: Article
• Language: English
• Subjects: Accretion; Cambrian; Deposition; Devonian; Evolution; Fossils; Geological time; Gondwana; Oceans; Palaeomagnetism; Paleoceanography; Paleomagnetism; Paleozoic; Polar wandering; Separation; South China
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2019GL083123

The paleogeographic relationship between South China and Gondwana is critical for understanding the dispersion of Gondwana, accretion of Asia, and evolution of the Paleo‐Tethys. However, the lack of robust Devonian paleomagnetic data prevents a confirmative reconstruction of South China's connection to Gondwana and its subsequent separation during the Paleozoic. Here we report a new paleopole (33.6°N, 236.4°E; A95 = 3°) from the Givetian red beds (~385 Ma) in central South China. Fitting apparent polar wander paths between South China and Gondwana suggests that South China was connected to East Gondwana from the earliest Cambrian to Early Devonian, with its position closed to NW Australia. Thereafter, South China separated from Gondwana during ~400–385 Ma, as evidenced by their decoupled apparent polar wander paths. The paleomagnetic data suggest that the Paleo‐Tethys Ocean between South China and East Gondwana had been up to ~1,600 km latitudinally wide by ~360 Ma. Plain Language Summary South China is thought to have drifted away from the north Gondwana margin during the Paleozoic. Two critical questions remain unanswered: (1) How did South China connect to Gondwana? (2) When and how did South China break up from Gondwana? Here we present new paleomagnetic evidence for the connection and separation between South China and Gondwana. Our results, in combination with existing data, suggest that South China was connected to East Gondwana from ~540 to ~400 Ma, with its position closed to northwest Australia. South China broke up from Gondwana during ~400–385 Ma, accompanied with the opening of the Paleo‐Tethys Ocean. By ~360 Ma, South China was separated from East Gondwana by the ocean with a N–S width of ~1,600 km. Key Points A new paleopole (33.6°N, 236.4°E; A95 = 3°) was obtained from the Givetian red beds (~385 Ma) in South China South China was connected to East Gondwana during ~540–400 Ma, with its position closed to northwest Australia South China broke up from East Gondwana during ~400–385 Ma and they were separated by an ocean with a N–S width of ~1,600 km by ~360 Ma