PhD in Geographical and Earth Sciences – Decoding tectonics and climate effects in incipient mountains: the Sierra Nevada (southern Spain) case study

This project aims to constrain the evolving topography of mountain belts and to understand how mountains grow. Constraining how topography of mountains change with time, therefore, is crucial for understanding sediment delivery to the basins and changes in atmospheric circulation. Evidence of the early history of mountain belts is limited, both onshore because of poor preservation of the sediments and offshore where the sedimentary record may be incomplete and/or complicated by other processes, such as onshore temporary storage and sediment reworking.

The Sierra Nevada (Spain) began to emerge above sea-level about 10 Myr. The mountain front, especially on the western side, is defined by active normal faults that have generated river knickpoints that propagate upstream, deeply incising the mountain flank. Upstream of the knickpoints, erosion rates are two orders of magnitude lower than in the steep river valleys, creating stable, gently sloping headwaters and mountain tops. It has been suggested that this low-relief morphology represents a relict landscape that is not affected by rapid erosion, because the limited river discharge at high elevations provides insufficient energy for the knickpoints to propagate further. An important implication of this hypothesis is that the plateau-like morphology of the headwaters is a direct result of erosion efficiency and, therefore, of climate. The fact that this morphology is common to many non-glaciated mountains in arid environments supports this hypothesis, which, however, has never been tested.

This project will test the above hypothesis by constraining the spatial variation of erosion rates as the mountain block of Sierra Nevada evolved through time by analysing the sediments of the Granada basin and the deposits of one of the alluvial fans that overlies the Granada Basin using the burial dating technique.