Accelerated Pleistocene exhumation and isostatic uplift along the Himalaya

Abstract

The Himalayan Mountains exhibit extreme topography, with the highest peaks and most incised rivers on earth. Rapid uplift, surface erosion and geomorphological changes have been taking place in the Himalaya throughout the late Cenozoic. Although the interactions among tectonics, climate, and surface erosion have been intensively studied over the past several decades, the landscape evolution and formation of extreme topography in the Himalaya are still unclear. Here, we present low-temperature thermochronology and thermal history modeling results that reveal the Makalu massif (∼87°E) in the central part of the Himalayan orogen may have experienced over 4 km of exhumation since 2 Ma. Combined with 1442 previously published cooling ages, we derive temporal and spatial variation in exhumation rates since 10 Ma for the entire Himalaya and reveal rapid cooling and exhumation since the Pleistocene. The isostatic response to this erosional unloading exhumation is quantified using a two-dimensional flexural model. Calculated results show that vertical uplift reached nearly 3200 m in the highest parts of the Himalaya orogen, suggesting that the isostatic response may play an important role in the building of relief and extreme topographic elevations since the Pleistocene.