Miocene high elevation in the Central Alps

Reconstructing Oligocene-Miocene paleoelevation contributes to our understanding of the evolutionary history of the European Alps and sheds light on geodynamic and Earth surface processes involved in the development of Alpine topography. Despite being one of the most intensively explored mountain ranges worldwide, constraints on the elevation history of the European Alps remain scarce. Here we present stable and clumped isotope measurements to provide a new paleoelevation estimate for the mid-Miocene (similar to 14.5 Ma) European Central Alps. We apply stable isotope delta-delta paleoaltimetry to near-sea-level pedogenic carbonate oxygen isotope (delta O-18) records from the Northern Alpine Foreland Basin (Swiss Molasse Basin) and high-Alpine phyllosilicate hydrogen isotope (delta D) records from the Simplon Fault Zone (Swiss Alps). We further explore Miocene paleoclimate and paleoenvironmental conditions in the Swiss Molasse Basin through carbonate stable (delta O-18, delta C-13) and clumped (Delta(47)) isotope data from three foreland basin sections in different alluvial megafan settings (proximal, mid-fan, and distal). Combined pedogenic carbonate delta O-18 values and Delta(47) temperatures (30 +/- 5 degrees C) yield a near-sea-level precipitation delta O-18(w) value of -5.8 +/- 1.2 parts per thousand and, in conjunction with the high-Alpine phyllosilicate delta D value of -14.6 +/- 0.3 parts per thousand, suggest that the region surrounding the Simplon Fault Zone attained surface elevations of > 4000 m no later than the mid-Miocene. Our near-sea-level delta O-18(w) estimate is supported by paleoclimate (iGCM ECHAM5-wiso) modeled delta O-18 values, which vary between -4.2 parts per thousand and -7.6 parts per thousand for the Northern Alpine Foreland Basin.

Automated summary

Reconstructing the Oligocene-Miocene paleoelevation of the European Central Alps reveals that the region attained surface elevations of >4000 m in the mid-Miocene (around 14.5 Ma), based on stable and clumped isotope measurements.