History of Holocene fluvial activity in Romania: evidences based on absolute dating

Abstract

Abstract-The main objective of this paper is to illustrate how was carried the reconstitution of geomorphological activity of rivers in Romania at different times of the Holocene based on the interpretation sedimentation contexts with dated samples, the sediment quality, their deposition styles, relict morphologies and others. The database compiled was processed using bivariate and multivariate statistical techniques or the probability distribution functions. The secondary objectives relate to: (i) Establishing a chronology of fluvial activity in Romania? (ii) How were felt Holocene climatic thresholds (identified in various proxies) in fluvial activity? (iii) How river chronology correlates with other environmental and geoarchaeological in our geographic area? (iv) In this research stage, we can explore some links with Central Europe fluvial chronologies?Keywords-fluvial chronologies; absolute dating; probability density functions; Holocene I. APPROACHING PREMISESRegarding the knowledge evolution on fluvial landforms and processes, the year 2010 stands out as a reference year in grouping the study objectives: (i) before 2010, the fluvial geomorphology research has focused mainly on present-day and modern channel dynamics, on fluvial processes related to human impact and other driving factors; (ii) after 2010, many notable attempts have occurred, with studies focused on the better understanding of the style and of the magnitude of channels changes for different timescales (secular, millennial, Late Holocene, Holocene, Late Glacial and transition to Holocene). Over the last 6 years several scientific studies based on absolute dating were published, with results correlated with multidisciplinary investigations. Due to the increased number of references on past climate and hydrological events, geomorphologists wanted to correlate them with the magnitude of fluvial activity, responsible for the morphologic and sedimentologic adjustment styles of river channels. The required information are stored in sedimentary archives (litho-stratigraphic units whose morphological, granulometric, geochemical, biological characteristics indicate the mechanisms and physical processes which contributed to their deposition) and are dated by one of the known techniques. Because these structures are rich in biogenic material, the most used method to evaluate their age was radiocarbon dating. [7,8], several hundreds of absolute dating of sedimentary archives were statistically approached and conclusions regarding the periods with high fluvial activity registered in the considered regions were obtained. In light of these results we want to report our own results throughout the objectives of the present study.In Romania, significant progress was achieved as regards the chronology of the Holocene.[9] summed the palaeoclimatic data sources and climate reconstructions for the last 15000 years in Romania. The fluvial sedimentary archives (from floodplain and floodplain terraces) and sedimentary archives from small sedimentary basins (small la...

Using archaeological and geomorphological evidence for the establishment of a relative chronology and evolution pattern for Holocene landslides

“…(A) human prehistory and history chronology(synthesized by [39] with slight modifications considering the advancements from [41], (B) human cultures in prehistory and history of Eastern Romania (synthesized by [39], (C) Blytt-Sernander classification system ([142] matched to Romania dates using information from [140]) (B–Bølling, OD–Older Dryas, A–Allerød, YD–Younger Dryas, PB–Preboreal, BR–Boreal, SBR—Subboreal, HCO–Holocene Climatic Optimum, SA–Subatlantic, RWP–Roman Warm Period, MCO–Medieval Climatic Optimum, LIA–Little Ice Age), (D) paleoclimatic reconstructions for Romania of wet vs. dry periods [67,68,140,141,143–145], (E) paleoclimatic reconstructions for Romania of warm vs. cold periods [140,141,143], (F) landslide activity for the studied sites (numbered according to Fig 1 and Table 1); (G) landslide activity for the sites from [39] (numbered according to Fig 1); Pleistocene to Holocene boundary is taken from [146]. https://doi.org/10.6084/m9.figshare.11340497.v1.…”

“…The general characteristics of the Last Glacial Maximum, Lateglacial and Holocene for the Central and Eastern Europe are used to draw some ideas about the environment of North-Eastern Romania because to the present day there are no detailed reconstructions of the paleo-environment in the Moldavian Plateau. There are only two exceptions with regard to the fluvial environments of the Siret River which were reconstructed by [67] for the last 6000 years based on wood C14 chronology, and another one regarding the fluvial and lake sediments of Romania, reconstructed by [68], for the last 12000 years using probability density functions (PDFs) of radiocarbon data.…”

“…Wet periods (also shown by the tree large radial growth), when hydro-geomorphological activity was higher, were identified [68] in the following periods: 6600–5700, 3700–2900, 2300–1900, 1000–900, 750–650, 450–350, 150–50 yr. BP. Spikes in humidity shown by tree ring growth for the last 12000 years are 10300, 9800, 9200, 8500, 8000, 6790, 5650, 3750, 3300, 2850, 2350, 1500, 1300, 880 and 500, while for the last 200 years these are 1824–1825, 1870–1871, 1890–1991, 1926, 1970 and 1997.…”