To better understand the Neotethyan paleogeography, a paleomagnetic and geochronological study has been performed on the Early Cretaceous Sangxiu Formation lava flows, which were dated from ~135.1 Ma to ~124.4 Ma, in the Tethyan Himalaya. The tilt-corrected site-mean characteristic remanent magnetization (ChRM) direction for 26 sites is Ds = 296.1°, Is = −65.7°, ks = 51.7, α95 = 4.0°, corresponding to a paleopole at 5.9°S, 308.0°E with A95 = 6.1°. Positive fold and reversal tests prove that the ChRM directions are prefolding primary magnetizations. These results, together with reliable Cretaceous-Paleocene paleomagnetic data observed from the Tethyan Himalaya and the Lhasa terrane, as well as the paleolatitude evolution indicated by the apparent polar wander paths (APWPs) of India, reveal that the Tethyan Himalaya was a part of Greater India during the Early Cretaceous (135.1–124.4 Ma) when the Neotethyan Ocean was up to ~6900 km, it rifted from India sometime after ~130 Ma, and that the India-Asia collision should be a dual-collision process including the first Tethyan Himalaya-Lhasa terrane collision at ~54.9 Ma and the final India-Tethyan Himalaya collision at ~36.7 Ma.
The precollisional locations and geometries of the Lhasa terrane (LT) are critical to constrain the India‐Asia collision. However, the inclinations of the Cretaceous paleomagnetic data obtained from the northern limb of folds are obviously lower than those obtained from the southern limb, which cause large discrepant paleolatitudes of the LT prior to India‐Asia collision. Here, we carried out a new paleomagnetic investigation on the Late Cretaceous Jingzhushan Formation red beds in the far western LT. The tilt‐corrected site mean direction yielded a palaeopole at 74.4°N, 226.0°E with A95 = 3.8° (N = 54). This paleomagnetic data set passes fold tests and indicates that the studied area was located at 19.6° ± 3.8°N during the Late Cretaceous. However, the mean inclination calculated from the northern limb of folds (Is = 19.0°) is significantly lower than that of the southern limb of folds (Is = 51.8°). This inclination discrepancy of the Jingzhushan Formation red beds may be attributed to the syntectonic sedimentation. Nevertheless, the site mean direction obtained from both limbs of folds is generally consistent with the site mean direction after syntectonic‐sedimentation correction. Our new paleomagnetic results, combined with the reliable Cretaceous paleomagnetic results from the LT showed that the southern margin of Asia had a present‐day relatively east‐west alignment prior to India‐Asia collision.
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