Geology and Tectonic Setting of the Cordillera Blanca

The Cordillera Blanca is situated in the northern Peruvian Andes and hosts some of the highest elevations in the Andean Range. Cored by a—granitic pluton and flanked by Mesozoic metasedimentary rocks and Cenozoic volcanics, the range harbors a portion of Andean geologic history spanning the last ~200 Ma. While the region is dominated by igneous rocks, this part of the Andes has not experienced active magmatism since ~5 Ma. One of the most striking features of the range is the active Cordillera Blanca Normal Fault, a ~200 km long fault accommodating extension and strike-slip deformation and enabling the high elevation glaciated peaks of the footwall block. While this region shares a similar geologic history with the rest of the Andean Range, including long-lived subduction and mountain building since the Mesozoic, the Cordillera Blanca is situated above a flat slab section of the downgoing Nazca Plate, which adds a complexity to the tectonic history of this region. Understanding the connection between the initiation and kinematics of this extensional crustal-scale fault set within and parallel to a contractional margin is an area of active research. The Quaternary geologic record preserves a rich record of Pleistocene glaciations and associated post-glacial landscape processes. The striking topography, geology, landforms, and active Earth processes that make this region an important archeological zone and modern tourist destination as well as a resource-rich location (e.g. hydroelectric power generation, metal mining, water resources for coastal agriculture) also expose the highly populated Callejón de Huaylas valley to geohazards such as mass wasting events, floods, and earthquakes.