The Tolmin Basin constitutes the western part of the Slovenian Basin, a large Mesozoic interplatform basin that was bounded to the north by the Julian Carbonate Platform and to the south by the ...Dinaric Carbonate Platform. Today, it is found along the structural boundary between the Southern Alps and the External Dinarides in northwestern Slovenia. After the drowning of the Julian Carbonate Platform, the Tolmin Basin was dominated by pelagic deposits, namely the Toarcian marlstones (Perbla Formation), the Aalenian to lower Tithonian siliceous limestones and radiolarites (Tolmin Formation), and the upper Tithonian to the Berriasian Biancone Limestone Formation. In this study, a basin-scale sedimentary evolution and calpionellid biostratigraphy of the latter is presented. The Biancone Limestone Formation is a calpionellid-bearing pelagic limestone typical of all deepened segments of the Adria microplate in this time interval. It is generally monotonous but shows considerable vertical and lateral variations. The lower boundary with radiolarites is sharp, revealing a pronounced and rapid overturn in pelagic sedimentation. The lower Berriasian slumps indicate a tectonic pulse. Rare beds of resedimented limestones, assigned to the middle Berriasian, are similar in composition to those intercalated in the underlying radiolarites. They thus show that the factors that led to a significant shift in pelagic sedimentation had little or no effect on shallow-marine carbonate production. In the upper Berriasian, an increase in clay content is evident in the formation, which is explained by the uplift and erosion of the propagating thrust belt in the Neotethys area, superimposed by humidification.
We present a paleoenvironmental reconstruction for the mountain fringe between the South-Eastern Alps and the Northern Dinarides (NE-Italy/W-Slovenia) during the Last Glacial Maximum. We focused on a ...new sedimentary and paleoecological archive spanning the LGM acme, located in an aggrading, permanently flooded and ponded plain, dammed by an active fluvioglacial megafan. The ecosystem reconstruction, based on two high resolution pollen records, is supported by a rich plant macrofossil flora and constrained by a robust radiocarbon chronology between 26 and 22calka BP. We show evidence for persistence of boreal trees and of different open boreal forest types throughout the LGM at the south-eastern mountain fringe of the Alps and the Northern Dinarides. Fire frequency is responsible for high, oscillating forest openness. The paleobotanical record is discussed in the light of the ecogeographic diversity of the region. A belt formed by Swiss stone pine, larch and dwarf mountain pine on limestone bedrock, and accompanied by Spruce in the floodplain, extended uphill, while proximal outwash plain supported Scots pine and dwarf mountain pine. These differences arise from groundwater regimes rather than from local climate variability. A steep moisture gradient from the semiarid pedoclimatic regime prevailing in the Adriatic alluvial plain to the forested mountain fringe is related to the orographic rainout triggered by southern air circulation. Mesophytic broad-leaved forest trees did not withstand the LGM temperature extremes in zonal ecosystems at the Alpine–Dinaric fringe; however, the fossil evidence suggests a number of microrefugia in karstic and thermal spring habitats of the northern Adriatic.
•Paleoenvironmental reconstruction at Alps–Dinarides fringe during the Last Glacial Maximum•Relationships between regional geological frame, sedimentary environments, and forest history•Persistence of trees and of different types of open boreal forest throughout the LGM
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