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Exhumation history of the eastern Tethyan Himalaya: Evidence from Apatite (U[sbnd]Th)/He Thermochronology.

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Title: Exhumation history of the eastern Tethyan Himalaya: Evidence from Apatite (U[sbnd]Th)/He Thermochronology.
Authors: Han, Xu1 (AUTHOR), Dai, Jin-Gen1 (AUTHOR) djgtibet@163.com, Liu, Bo-Rong1 (AUTHOR), Yu, Zhi-Cheng1 (AUTHOR)
Source: Tectonophysics. Jan2026, Vol. 920, pN.PAG-N.PAG. 1p.
Subjects: Tectonic exhumation, Erosion, Valleys, Geological time scales, Structural geology, Climate change
Geographic Terms: South Asia, Himalaya Mountains
Abstract: The Himalayan orogen is an ideal natural laboratory for investigating exhumation processes due to the diverse and distinctive tectonic and climatic features. Whereas numerous low-temperature thermochronometric studies have been conducted on southern flank of the orogen (mainly in the Greater Himalaya and Lesser Himalaya), the dominant controls on exhumation remain debated due to the complex interactions between climate, topography, and tectonics. In contrast, the Tethyan Himalaya along the northern flank exhibits relatively limited recent tectonic activity and spatially uniform precipitation, which makes it more suitable for exploring controlling factors of exhumation. To reconstruct the exhumation history of the eastern Tethyan Himalaya and identify its controls, we collected bedrock samples along river channels for apatite (U Th)/He dating. Low-temperature thermochronology and thermal history modeling indicate three rapid exhumation phases: ca. 10–7 Ma, ca. 6–3 Ma, and ca. 2–0 Ma. The ca. 10–7 Ma phase correlates with the Asian summer monsoon intensification, during which increased precipitation enhanced fluvial incision. The ca. 6–3 Ma phase is the last vestige of tectonically controlled rapid exhumation in Himalaya, subsequent to the decline of the India-Asia convergence rate at ca. 6 Ma. The most recent phase (<2 Ma) is primarily linked to localized normal faulting. Additionally, a pronounced geomorphic contrast is observed: river valleys south of the Himalayan drainage divide exhibit significantly wider widths compared to tributaries of the upper and lower Yarlung River located north of the divide. These differences correlate with exhumation timing, as areas experiencing older exhumation phases exhibit wider valleys. This correlation suggests that fluvial erosion exerts a long-term control on exhumation patterns within the orogen. • Three rapid exhumation phases in eastern Tethyan Himalaya occurred at ca. 10–7, 6–3, and 2–0 Ma. • Increased rainfall drove river incision, which caused rapid exhumation during ca. 10–7 Ma. • Older exhumation processes correspond to wider river valleys. [ABSTRACT FROM AUTHOR]
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Abstract:The Himalayan orogen is an ideal natural laboratory for investigating exhumation processes due to the diverse and distinctive tectonic and climatic features. Whereas numerous low-temperature thermochronometric studies have been conducted on southern flank of the orogen (mainly in the Greater Himalaya and Lesser Himalaya), the dominant controls on exhumation remain debated due to the complex interactions between climate, topography, and tectonics. In contrast, the Tethyan Himalaya along the northern flank exhibits relatively limited recent tectonic activity and spatially uniform precipitation, which makes it more suitable for exploring controlling factors of exhumation. To reconstruct the exhumation history of the eastern Tethyan Himalaya and identify its controls, we collected bedrock samples along river channels for apatite (U Th)/He dating. Low-temperature thermochronology and thermal history modeling indicate three rapid exhumation phases: ca. 10–7 Ma, ca. 6–3 Ma, and ca. 2–0 Ma. The ca. 10–7 Ma phase correlates with the Asian summer monsoon intensification, during which increased precipitation enhanced fluvial incision. The ca. 6–3 Ma phase is the last vestige of tectonically controlled rapid exhumation in Himalaya, subsequent to the decline of the India-Asia convergence rate at ca. 6 Ma. The most recent phase (<2 Ma) is primarily linked to localized normal faulting. Additionally, a pronounced geomorphic contrast is observed: river valleys south of the Himalayan drainage divide exhibit significantly wider widths compared to tributaries of the upper and lower Yarlung River located north of the divide. These differences correlate with exhumation timing, as areas experiencing older exhumation phases exhibit wider valleys. This correlation suggests that fluvial erosion exerts a long-term control on exhumation patterns within the orogen. • Three rapid exhumation phases in eastern Tethyan Himalaya occurred at ca. 10–7, 6–3, and 2–0 Ma. • Increased rainfall drove river incision, which caused rapid exhumation during ca. 10–7 Ma. • Older exhumation processes correspond to wider river valleys. [ABSTRACT FROM AUTHOR]
ISSN:00401951
DOI:10.1016/j.tecto.2025.231035