Palaeomagnetism of the mid-Cretaceous red beds from the Tethyan Himalaya: direction discrepancy and tectonic implications

Abstract

Understanding the northern extension of Greater India is vital for modeling the India-Asia collision process and the formation of the Tibetan Plateau. We present new palaeomagnetic data from the mid-Cretaceous (ca. 106 Ma) Gyabula Formation red beds in the Tethyan Himalaya. Well-defined high laboratory unblocking temperature component magnetizations were isolated from 19 sites and pass the fold tests, indicating that they are pre-folding magnetizations. The tilt-corrected site-mean direction is D s = 222.9°, I s = +39.4° with α 95 = 4.2°. The site-mean inclination increases from 39.4° to 45.8° after anisotropy-based inclination shallowing correction. The declination and inclination differ considerably from those of neighboring sections. This directional discrepancy of the red beds may be attributed to the fact that the sampled section (sites ZB1–11, 40–52) is overturned and local vertical axis rotation. The combination of our new and previously published palaeomagnetic data shows that the Tethyan Himalaya was located at 27.5° ± 2.4°S for the sampled area. Our new results, together with the reliable Cretaceous palaeomagnetic data obtained from the Tethyan Himalaya as well as coeval palaeolatitudes expected from the Indian craton, support a smaller Greater India and that the Tethyan Himalaya did not rift from the Indian craton during the mid-Cretaceous. Thematic collection: This article is part of the Mesozoic and Cenozoic tectonics, landscape and climate change collection available at: https://www.lyellcollection.org/topic/collections/mesozoic-and-cenozoic-tectonics-landscape-and-climate-change Supplementary material: https://doi.org/10.6084/m9.figshare.c.6795683