Abstract
•Secondarily acquired magnetization prevails in Early Cretaceous rocks on the Sikhote Alin Superterrane.•Such magnetization shows anomalously large clockwise deflected declination (D=127.5°).•Large clockwise rotation is expected for the Sikhote Alin Superterrane with respect to Eurasia.•The Sikhote Alin Superterrane kept its E–W elongated orientation before the start of rotation.
We present new Early Cretaceous paleomagnetic results from the Zhuravlevka-Amur Terrane of the Eurasian Continent, Far East Russia. Out of 34 total sites, 14 were collected from Komsomolsk-on-Amur area (50.6°N, 137.2°E) and 20 from Vaninsky area (49.1°N, 139.2°E). Thermal demagnetization reveals the presence of two interpretable magnetization components in 19 sites, with laboratory unblocking temperatures of 350°C and/or 500–580°C. The remanent directions of the low-temperature component are either parallel or anti-parallel to those obtained from the high-temperature component. Results of fold tests show that both components are secondary. Rock magnetic and reflected light microscopic observations indicate a chemical origin for both of these components, as evident from the presence of secondary pyrrhotite and magnetite. The Komsomolsk-on-Amur area provides an in-situ formation mean direction of D=127.5°, I=66.7° (k=28.2, α95=9.3°, N=10 sites). When combined with the reported paleomagnetic data from Early to Middle Cretaceous accretionary wedge rocks of the Kiselevka-Manoma Terrane and the Early Cretaceous Western Sakhalin turbidite basin rocks (D=94.2° and D=57.1°, respectively), large magnitude of clockwise rotations of 66–118° is demonstrated for the eastern part of the Sikhote-Alin Superterrane with respect to Eurasia. In addition, these three landmasses maintained their E–W elongated orientations before the start of rotation, implying southward directed subduction of the oceanic plates beneath northern margins. These reconstructions of the Sikhote-Alin Superterrane provide clues on the tectonic evolution of Panthalassa Ocean.