|Title||Preliminary early cretaceous paleomagnetic results from the Gansu Corridor, China|
|Publication Type||Journal Article|
|Year of Publication||1995|
|Authors||Frost G M, Coe RS, Meng Z, Peng Z, Chen Y, Courtillot V, Peltzer G, Tapponnier P, Avouac J-P|
|Journal||Earth and Planetary Science LettersEarth and Planetary Science Letters|
We report results from our paleomagnetic study of Lower Cretaceous redbeds from the Gansu Corridor, northwestern China. The characteristic remanent magnetization (ChRM) resides in hematite, often at very high unblocking temperatures (> 660 degrees C). The directions associated with this component exhibit only reversed polarities from locality A (Sunan area), but the samples from locality B (Lanzhou area, 480 km to the southeast) show roughly antipodal normal and reversed polarities. The combined sample directional data from both localities pass a fold test at the 99% confidence level. The mean paleomagnetic pole is located at 48.7 degrees N, 199.7 degrees E, with A(95) = 4.1 degrees, which is discordant with poles of similar age elsewhere from neighboring regions in China. Although represented by relatively few samples (N = 21) this pole suggests that significant post-Cretaceous motion may have occurred between the Gansu Corridor and adjacent blocks. Relative to Eurasia or North China, the discordance corresponds to 28.1 +/- 5.2 degrees or 35.6 degrees +/- 9.7 degrees clockwise rotation and 9.5 degrees +/- 4.5 degrees or 9.8 degrees +/- 8.2 degrees northward displacement respectively. The rotations support, but do not yet distinguish between, several neotectonic models assumed to have acted over the past 15-40 m.y. The displacement is not predicted by any of these models; if real, it may have occurred early in the history of the India-Asia collision, or even before.