Temporal Relationship of Increased Palaeodischarges and Late Glacial Deglaciation Phases on the Catchment of River Maros/Mureş, Central Europe

Abstract

River Maros/Mureş has one of the largest alluvial fans in the Carpathian Basin. On the surface of the fan several very wide, braided channels can be identified, resembling increased discharges during the Late Glacial. In our study we investigated the activity period of the largest channel of them, formed under a bankfull discharge three times higher than present day values. Previous investigations dated the formation of the palaeochannel to the very end of the Pleistocene by dating a point bar series upstream of the selected site. Our aim was to obtain further data on the activity period of the channel and to investigate temporal relationships between maximum palaeodischarges, deglaciation phases on the upland catchment and climatic amelioration during the Late Pleistocene. The age of sediment samples was determined by optically stimulated luminescence (OSL). The investigation of the luminescence properties of the quartz extracts also enabled the assessment of sediment delivery dynamics in comparison to other palaeochannels on the alluvial fan. OSL age results suggest that the activity of the channel is roughly coincident with, but slightly older than the previously determined ages, meaning that the main channel forming period started at 13.50±0.94 ka and must have ended by 8.64±0.82 ka. This period cannot directly be related to the major phases of glacier retreat on the upland catchments, and in terms of other high discharge channels only the activity of one overlaps with a major deglaciation phase at ~17-18 ka. Based on these, high palaeodischarges can be rather related to increased Late Glacial runoff, resulted by increasing precipitation and scarce vegetation cover on the catchment. Meanwhile, the quartz luminescence sensitivity of the investigated channel refers to fast sediment delivery from upland subcatchments. Therefore, the retreat of glaciers could affect alluvial processes on the lowland by increasing sediment availability, which contributed to the development of large braided palaeochannels.

The Role of Past Climatic Variability in Fluvial Terrace Formation, a Case Study from River Mureş (Maros), Romania

“…Some parts of the catchment, especially the Retezat Mountains, were glaciated in glacial periods. The proportion of these areas compared to the entire area of the catchment is low, and deglaciation did not contribute considerably to lowland discharges [34]. The channel sediments are dominated by coarse sand and fine gravel at the study site; however, the river also carries a large amount of suspended sediment, eroded mostly along its way through the Transylvanian Basin.…”

“…However, on the lowlands of the Carpathian Basin, steppe vegetation was mostly characteristic [54]. MIS 3 can also be characterized by a more pronounced seasonality in the entire Northern Hemisphere [55] and also in the region [54], thus explaining the initiation of sediment pulses towards the Mureş (Maros) Valley from the glaciated regions of the catchment [34] and the aggradation of a significant valley fill in spite of potential tectonic forcing at the site.…”

“…It also has to be kept in mind that compared to MIS 3, the Bølling-Allerød and later the Holocene periods were warm and humid; thus, the mobilization of LGM deposits is recorded by subsequent sediment pulses on the alluvial fan of the river [34,71]. Due to the fast response of vegetation to warming [54], the system could reach a supply-limited state again but in an interstadial and interglacial climate, conditions which inevitably favor incision (Figure 5).…”

First report on dendrochronological and radiocarbon studies of subfossil driftwood recovered across the Mureş/Maros Alluvial Fan

“…Driftwood samples were recovered either along the present course of the river, or in the vicinity of an avulsion node to the north (Fig. 5), where major shifts in flow direction took place in the Late Glacial and in the beginning of the Atlantic Phase, possibly in response to significant changes in the sediment regime during these periods (Bartyik et al, 2021). In terms of the sites along the present-day course of the river, no previous geochronological data are available.…”

Alluvial ridge development and structure: Case study on the Upper Tisza, Hungary

“…12-13 ka ago, thick overbank fines deposited in C and F alluvial ridges (at the A ridge they were not revealed, probably because there the pit was not deep enough: its bottom sediments are 8.65 ka old). This increased fluvial activity could be related to the last deglaciation of the Carpathians (Bartyik et al, 2021), and the cool and dry climate during the Younger Dryas when the vegetation became sparse and the runoff intensified (Járainé-Komlódi, 1969).…”