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The Cordillera Blanca batholith (12–5 Myr) forms the highest Peruvian summits and builds the footwall of the Cordillera Blanca normal fault (CBNF). Even if several models have been proposed, the processes driving both the exhumation of the Cordillera Blanca and extensional deformation along the CBNF are still debated. Here we quantify the emplacement depth and exhumation of the batholith of the northern Peru arc from the late Miocene to present. Based on a compilation of crystallization ages and new thermobarometry data in the Cordillera Blanca batholith, we propose that the batholith was emplaced at a depth of ~3 km in successive sills from 14 to 5 Ma. By contrast, the younger rocks exposed at the surface were emplaced the deepest (i.e., ~6 km) and are located close to the CBNF, suggesting post 5 Ma tilting. Furthermore, a formal inversion of the thermochronologic data indicates an increase of the exhumation rates in the Cordillera Blanca during the Quaternary. The higher predicted exhumation rates correlate with areas of high relief, both in the northern and central part of the Cordillera Blanca, suggesting that Quaternary valley carving by glaciations have a significant impact on the latest stage of the Cordillera Blanca exhumation (2–0 Ma).

[1] By regressing simple, independent variables that describe climate and tectonic processes against measures of topography and relief of 69 mountain ranges worldwide, we quantify the relative importance of these processes in shaping observed landscapes. Climate variables include latitude (as a surrogate for mean annual temperature and insolation, but most importantly for the likelihood of glaciation) and mean annual precipitation. To quantify tectonics we use shortening rates across each range. As a measure of topography, we use mean and maximum elevations and relief calculated over different length scales. We show that the combination of climate (negative correlation) and tectonics (positive correlation) explain substantial fractions (>25%, but

[1] Temperature-time histories of rocks are often used to constrain the kinematics of tectonic events, the evolution of landforms, erosion rates, and/or amount of faulting in tectonically active areas. However, interpretations based on thermal histories are not always straightforward as they rely on several interdependent mechanisms such as heat conduction, heat advection, or the presence of transient topography that must be taken into account. Using a three-dimensional finite element code recently developed by one of the authors, we have calculated temperature-time histories to interpret an existing thermochronological data set (K-Ar and FT) complemented by new low-T thermochronometer data ((U-Th)/He and FT) from the Southern Alps of New Zealand. Combined with inversion methods (Genetic Algorithm and Neighbourhood Algorithm), the model is used to derive from the data information on the tectonomorphic development of the orogen during the Pliocene and Pleistocene epochs. Assuming a quasi-geomorphic steady state, we can constrain the rate of tectonic horizontal advection and vertical uplift as well as the geometry of the main structural boundary, i.e., the Alpine Fault. We can also explain the along-strike geometry of the metamorphic isograds and thermochrons in relationship to surface topography. Furthermore, we show that if one assumes that the landscape has not been horizontally transported by tectonic movement, the relief on the west coast of the Southern Alps has increased. This relief increase could have been initiated at any time between 1.5 Ma and 100 ka. Any relief reduction during this period is ruled out by our modeling. Alternatively, if the landscape is advected horizontally in the direction normal to the trace of the Alpine Fault, a relief increase is not required to explain the thermochronological data.