Exhumation and uplift of the Northern Peruvian Andes

Abstract

The Transcontinental Amazon Basin, home of one of the most biodiverse ecosystems on earth, is accepted to have been stablished by the Late Miocene, having evolved from a megawetland in the Middle Miocene (~11 Ma). However, the present-day vast biodiversity was established later, prior to the Pleistocene (ca. 3 Ma). Both the establishment of the current diversity and the development of the basin are suggested to have been closely related with the uplift of the Andes, specifically with the attainment of a critical elevation capable of blocking moisture from the Amazon and form orographic precipitation. Thus, the determination of the timing and rates of such surface uplift are crucial to understand the role of this event in the creation of the basin and the development of the biodiversity, as well as to explain a potential lag-time between both events. Along the Andes, constraints on surface uplift are available in the North, in Colombia and in the South, in the Central Andean Altiplano region. However, very few information is available for the Northern Peruvian Andes, which comprises a significant portion of the Western edge of the Amazon Basin. In order to have such information, I propose to conduct a multi technique analysis using low-temperature bedrock thermochronology to date the exhumation, stable isotope geochemistry for paleoaltimetry determinations, and cosmogenic nuclide, luminesce dating and morphometric analyses in fluvial terraces to date Quaternary uplift. Published molecular phylogenetic data will be used along with the calculated uplift rates to stablish its relationship with diversification events and the suitability of such data to be used as paleoaltitudinal proxies. (AU)