Burial dating of fluvial terraces using cosmogenic nuclides, ArieÛ River

Dating of the fluvial terraces and providing a morphochronological picture has always been part of a controversial scientific debate, both locally and globally. The rivers in the Transylvanian Basin were studied between 1960 and 1980 and mainly focused on the number of teracces, the timing of river incision and how these terraces are represented in a palaeoreconstruction framework. In most cases, these studies were based on sedimentology, palynology, palaeontology, and archeology, but their chronological history has never been established. Surface exposure dating using the 10Be and 26Al cosmogenic nuclides would be an ideal dating method; however, river terrace deposits are made of individual clasts, each with their unique complex history of an initial exposure during exhumation and fluvial transport and then burial. This study is based on the numerical dating of the River Arieş terraces in the Corneşti – Plăieşti area using the cosmogenic burial dating method. The morphological features of the study area were initially mapped in the field using topographical maps (1:25 000), geological maps (1:50,000), and orthophotographs (50 cm resolution). The cosmogenic samples were collected from three different terraces from depths down to 12-15 m from newly excavated parts within the study area. The 10Be and 26Al burial dating of these river terraces yields palaeoincision rates in the upper basin during the terraces deposition, provides age estimates for these deposits and further argues for the role of climate and tectonics in the deposition and subsequent incision of the terraces. Keywords— fluvial terraces; cosmogenic nuclides; burial dating; Romania; Arieş