Paleotopography and erosion rates in the central Hangay Dome, Mongolia: Landscape evolution since the mid-Miocene

• There is evidence of significant topographic relief in the Hangay Dome at 13 Ma.
• The Hangay Dome has been eroding at a rate of ∼41 m/Myr for the past ∼7 Myr.
• This study finds no geomorphic evidence of recent, rapid uplift in the Hangay Dome.
• Topographic relief in the modern Hangay Dome likely reflects climate forcing.

Standing over 2 km above the surrounding topography and flanked by orogen-scale strike-slip faults, the Hangay Dome in central Mongolia is characterized by long wavelength high topography, basaltic eruptions spanning 30 million years, and an abundance of flat-topped summit plateaus. However, despite decades of research, the origin and timing of the intraplate Hangay Dome uplift continues to be debated. Using Landsat imagery, GIS, and cosmogenic beryllium-10, we employ geomorphic investigations of (1) paleotopography preserved beneath basalt flows of known age, (2) erosion rates at various temporal scales, and (3) the relative contribution of glacial activity to total erosion to provide insight into the nature of landscape evolution in the Egiin Davaa region of the central Hangay Dome since the middle Miocene. Reconstruction of paleo-valleys cut into Paleozoic basement rock that exhibit a degree of local relief (>600 m) similar to the modern landscape, sluggish mean erosion rates (<45 m Myr−1), and dominance of glacial erosion suggest that there has been no dramatic change in tectonic forcing of the study area since ∼13 Ma, and that high amplitude climate oscillations beginning in the Pliocene have led to an environment influenced primarily by the activity of glaciers. These results provide support for uplift onset during the Oligocene or early Miocene, quantify landscape evolution since the middle Miocene, and underscore the importance of considering geomorphic archives found on Earth’s surface when building models of intra-continental epeirogeny.