New Early Permian Paleomagnetic and Geochronological Data From the Xilinhot–Songliao Block and Their Implications for the Relationship Between the Paleo‐Asian Ocean and the Paleo‐Tethys Ocean

The paleogeographic position of the Xilinhot–Songliao Block (XSB) is crucial to understand the spatiotemporal relationship between the Paleo‐Asian Ocean (PAO) and East Paleo‐Tethys Ocean (EPTO) tectonic domains. However, the lack of robust early Permian paleomagnetic data in the XSB has led to uncertainty in its paleogeographic position. Here, we report a well‐dated (286.1–281.25 Ma) paleomagnetic pole (38.4°N/17.6°E, A95 = 4.0°) from andesites of the Dashizhai Formation in the XSB. We combined our paleomagnetic data with available geological and paleontological data to reconstruct the paleogeographic relationship between the PAO and EPTO. The XSB was located on the northern margin of the EPTO at ∼285 Ma, suggesting that the northern boundary of the EPTO tectonic domain extended to the southern margin of the XSB, the Hegenshan Ocean (between the XSB and the Mongolia Block) corresponds to the eastern PAO, and the XSB separated the eastern PAO and EPTO at ∼285 Ma. Plain Language Summary The evolution of the Paleo‐Asian Ocean (PAO) and the East Paleo‐Tethys Ocean (EPTO) tectonic domains constructed the late Paleozoic paleogeographic pattern of Central and East Asia. Due to contradictions between the tectonic paleogeography and paleobiogeography of the Xilinhot–Songliao Block (XSB) during the early Permian, the spatiotemporal relationship between the two tectonic domains has been unclear. In this study, we present well‐dated paleomagnetic constraints on the paleogeographic position of the XSB at ca. 285 Ma. We provide a new reconstruction for the Northeast Asian block, which suggests that the XSB was located between the eastern PAO and the EPTO during that time and was the intermediate unit that separated the two tectonic domains. Key Points The Xilinhot–Songliao Block (XSB) was located at ∼19.3°N on the northern margin of the East Paleo‐Tethys Ocean (EPTO) at 285 Ma The northern boundary of the EPTO tectonic domain extended to the southern margin of the XSB The Hegenshan Ocean between the XSB and Mongolia Block was the main ocean basin of the eastern Paleo‐Asian Ocean at 285 Ma