The Tibetan-Himalayan paleotopography – TIBETOP

Assessing the evolution of the Earth’s surface, one of the most important drivers of abiotic and biotic processes, remains a major challenge of Earth and Environmental Sciences today. The Earth’s surface elevation reflects the interplay between deep and surface processes. The world’s highest Himalaya Mountains and Tibetan plateau represent a natural laboratory to obtain models linking topography, geodynamic processes, drainages, biodiversity and climate. However, different topographic growth scenarios are proposed for the Himalayan-Tibetan orogen, and a fierce debate currently occurs involving several international groups, including our own. This lack of consensus can be attributed to: 1) the still sparse coverage in space and time of paleoelevation data, which are mostly concentrated in basins, leaving the adjacent orogenic belts virtually unconstrained; 2) the poor dating and stratigraphic correlations of most study sites; 3) the reliability of paleoaltimetry proxies that, if altered, can lead to defective isotopic signatures. This project ambitiously proposes to unlock these limitations by applying new game-changing paleoaltitude proxies on new priority targets including exhumed deep crustal rocks now forming topographic highs. We will also revise the paleoaltitude and age constraints from associated basins enabling to assess the spatiotemporal interactions with adjacent tectonism and rock uplift. The isotopic composition of ancient meteoric water will be applied to 1. Hydrous synkinematic minerals from deformation zones, 2. Quartz veins, 3. Volcanic glasses, and 4. Carbonates rocks. Tracking palaeofluids from the Earth’s surface down to the lower crust makes TIBETOP unique. In addition to palaeoaltimetry estimates, new insights on crustal-scale fluids transport, and exhumation processes of deep orogenic crust will be gained. Our results will be integrated in paleogeographic maps to constrain climate, surface processes and vegetation models.