When rainfall trapped in fluid inclusion restores the relief of an orogen: Insights from the Cenozoic Himalayas

The involvement of meteoric water in orogens dynamics through surface processes is well known as for example in the Himalayas where erosion, resulting of the interplay between climate and tectonics shapes the most spectacular landscapes on the planet. But what about more internal and deepest surface fluid infiltration? Here we report analysis of the delta 18O(water) and delta D(water) of extracted water from fluid inclusions hosted into Cenozoic quartz veins sampled in the core of the Himalayan range, near the Main Central Thrust and the South Tibetan Detachment. Isotopic and microthermometric values suggest a meteoric origin for the fluids trapped in the quartz of syn-to post-kinematic veins formed between 10 to 20 km depth. Moreover, the isotopic compositions obtained in this study on quartz fluid inclusions water collected along a transect across the Himalayan range evolved with the topography in a similar manner than the modern meteoric water. Considering the age of formation of the quartz veins between 18 and 12 Ma, we deduce that the morphology of the Himalayan topographic front was already shaped during the Miocene but located further north. (c) 2023 Elsevier B.V. All rights reserved.

Automated summary

The study analyzed the water isotopes (delta 18O(water) and delta D(water)) of fluid inclusions in Cenozoic quartz veins from the core of the Himalayan range. The results suggest that the fluids originated from meteoric water and formed at depths of 10 to 20 km. The isotopic compositions of the quartz fluid inclusions water varied with topography in a similar manner to modern meteoric water. The findings indicate that the topographic front of the Himalayan range was already formed during the Miocene but located further north.