First Paleomagnetic and Geochronological Results From the Early Cretaceous Volcanic Rocks in the Western Tethyan Himalaya: Contribution to the Breakup of Eastern Gondwana and the Paleogeography of Neo-Tethys Ocean

Abstract

The temporal-spatial relationships of widely distributed latest Jurassic–Early Cretaceous igneous rocks in the Tethyan Himalaya (TH) are crucial for understanding the breakup of eastern Gondwana and the paleogeography of the Neo-Tethys Ocean. However, no paleomagnetic data are available from the Early Cretaceous volcanic rocks in the central-western TH. Here, we report the first paleomagnetic and geochronological results from Early Cretaceous volcanic rocks, dated at ∼144‒142 Ma, in the western TH. The tilt-corrected site-mean direction for 31 sites is Ds = 303.9°, Is = −58.7° with α₉₅ = 4.3°, yielding a mean pole at 1.9°N, 303.2°E (A₉₅ = 5.0°) and a paleolatitude of 40.8 ± 5.0°S for the Zhongba area. Positive fold and reversal tests support pre-fold primary magnetizations. Our paleomagnetic and geochronological results, combined with those from the eastern TH, northeastern India, and southwestern Australia, reveal that the latest Jurassic–Early Cretaceous volcanic rocks were emplaced across a paleolatitudinal range from approximately 40.8°S to 55.5°S, with a central paleolatitude of about 48.2°S, which is consistent with the present-day latitude of the Kerguelen Mantle Plume (KMP). This, along with the affinity of these rocks to the KMP-related magmatic rocks supports that the latest Jurassic–Early Cretaceous TH igneous rocks originated from the KMP, and that the KMP contributed to the breakup of eastern Gondwana. Comparison of Early Cretaceous paleolatitudes observed from the western TH and Lhasa terrane shows that the latitudinal width of the Neo-Tethys Ocean was ∼6,600 km at ∼144–142 Ma.