Title: Evolution of the Southern Margin of the Julian Basin with Emphasis on the Megabeds and Turbidites Seqence of the Southern Julian Prealps (NE Italy)
Abstract:From the Maaslrichtian up to the Early Eocene, the Julian (or Slovenian) Basin is characterized by a mixed siliciclastic/carbonale deposits system which exhibit complex sedimentalion patterns dependin...From the Maaslrichtian up to the Early Eocene, the Julian (or Slovenian) Basin is characterized by a mixed siliciclastic/carbonale deposits system which exhibit complex sedimentalion patterns depending on various controls: sea level changes; tectonic movements in both carbonate platform and northern source areas; subsidence; proximity/distality to siliciclastic, calciclastic, allodapic (carbonate) sediment source areas; abundance of terrigenous detritus; paleomorphology of the slope of the Friuli Platform, the main source of carbonate detritus. The depositional sequences ofthe Julian Basin are the result of these controls and their interaction. Herein the examination of the stratigraphic sections is restricted to the Middle Paleocene up to the Early Eocene (Flysch di Masarolis and Flysch del Grivo),where the most important carbonate are recognized. Fourteen stratigraphic sections of the with megabeds sequence were examined (mainly along the N-S direction). All sections are located near the southern margin of the basin, at the foot of the slope of the north-eastern edge of the Friuli Platform. Comparison of log s revealed marked differenoes in the thickness of the and of the interbedded calciturbidites and siliciclaslic turbidites. This could be ascribed to the proximity to the source areas of mega beds and to the abrupt stope morphology. By means of the litho-biostratigraphic analysis of the sedimeents which filled the Julian Basin, the provenances from the main source areas are outlined. The prevailing calciclastic detrilus (CE ,I) mixed with allodapic carbonate sediments (CI) came from the South; siliciclastic detritus (N CE) mixed with other calciclastic detritus (CE, II) from N, NW as consistently indicated by paleocurrent directions; minor (and late) mixed carbonate sediments (CE, ill) came from NE. A rough sedimentary balance comprising megabeds, thick beds, multisource turbidites (siliciclastic, carbonate, mixed plus couplets) is calculated. An attempt to apply the eustatic sea level curve of Haq et al. (1987) to Maastrichtian-Paleocene and Eocene deposits of the Julian Basin is made. Lowstands of the Maastrichtian- Paleocene and of the Late Ypresian are well recognizable. More problem s arise upon examining the Flysch del Grivo section which is slrongly controlled by tectonic mechanisms. The triggering mechanisms for mega bed emplacement in the Julian Basin is related to seismic activity along the southern border of the basin. In conclusion, the with megabeds sequence is integrated within the framewot;k of the geological evolution of the Julian Basin.Read More
Publication Year: 1992
Publication Date: 1992-08-20
Language: en
Type: article
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Cited By Count: 23
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