Water-level changes and their effect on deepwater sand accumulation in a lacustrine system: a case study from the Late Miocene of western Pannonian Basin, Hungary

Abstract

Major deepwater sand accumulations are known to be connected to sea-level lowstands in marine basins, due to the relative lack of accommodation space on the shelf. This model was tested for the Late Miocene Lake Pannon, a large endorheic lake depositing a sedimentary succession up to 3-4 km thick. The progradation of the shelf between 9.7 and 6 Ma was tracked along a 2D seismic network. The shelf-edge trajectory indicates continuous, moderate lake-level rise between 9.7 and 9 Ma. This is followed by alternating intervals of quasi-steady and rapidly rising relative lake level with a period of ca. 250 ky. However, due to the lack of significant lake-level drops, no third-order sequence boundary was identified in the studied time span (9.7-6 Ma). The sand ratio of the deepwater deposits does not show strong correlation with these lakelevel changes; moreover, the units deposited under rising lake-level conditions generally contain slightly larger proportion of sand. These features can be explained by the climatic origin of water-level rises: increasing precipitation enhances not only water inflow, but also sediment influx, which can overwhelm the well-known effect of accommodation space on the sand transport toward the deep water. The results suggest that shelf-margin trajectory might not be an efficient tool for predicting deepwater accumulations of sand in endorheic lacustrine basins.

Constraining forcing factors and relative sea-level fluctuations in semi-enclosed basins: the Late Neogene demise of Lake Pannon

“…From this high position, gravity mass flows transported the sediments across the shelf and up to 30 km past the shelf edge (Sztanó et al ., ). Within the progradational deposits, an alternation of progradational and aggradational clinothems is evident which is thought to result from a 4th order type of cyclicity (Uhrin & Sztanó, ; Sztanó et al ., ). These cycles may be orbitally forced; eccentricity forcing was previously shown to have an effect on sedimentation in the Vienna Basin part of Lake Pannon (Harzhauser et al ., ; Lirer et al ., ).…”

“…A depositional model for the infill of the Pannonian Basin has previously been developed for the central and western parts of the Pannonian Basin (Uhrin & Sztanó, ; Sztanó et al ., ). This model is based on the depositional geometries observed in the Makó Trough and near the western basin margin, both of which resulted from progradation in front of the paleo‐Danube.…”

Late Miocene sedimentary record of the Danube/Kisalföld Basin: interregional correlation of depositional systems, stratigraphy and structural evolution

“…Its progradation is related to the high clastic sediment input arriving via fluvial and deltaic feeder systems to Lake Pannon. Cyclic variations of sediment input and lake level influence the rate of slope progradation vs. aggradation (Uhrin & Sztanó 2012;Sztanó et al 2013b). On the upper part of the slope, sand bodies related to shelf-edge deltas and sandy canyon-fills may occur.…”

Re-evaluation of the Triassic sequence in the subsurface of the Little Plain Basin Hungary: A case study from the Győrszemere-2 well

“…The shelf-margin slopes prograded across the basin from 10 to 9 My ago, from a NW-N direction. Delta, delta plain, and later sediments of the alluvial plain were deposited until the present (Juhász 1991(Juhász , 1998Uhrin and Sztanó 2011;Magyar et al 2012). …”