Western Tethyan Epeiric Ramp Setting in the Early Triassic : An Example from the Central Dinarides (Croatia)

Summary, in English

In the central part of the External Dinarides in Plavno, Croatia, near Knin, a remarkably thick (927.5 m) Early Triassic depositional sequence was investigated. The Plavno sequence starts in the EarlyGriesbachian and ends with a continuous transition into the Anisian strata. A complete ¹³C isotope curve has been achieved and combined with conodonts, bivalves and ammonoids to establish and correlate stage and substage boundaries. The δ¹³C curve is consistent with former studies. It displays a general increase from the Griesbachian to a prominent maximum beyond the +8‰ amplitude around the Dienerian-Smithian boundary (DSB), followed by a steep and continuous decline to low, negative values in the Smithian. Around the Smithian-Spathian boundary (SSB) a steep rise to a second maximum occurred. It is followed by a saw-tooth shaped decline in the Spathian and a similar increase to a peak at the Spathian-Anisian boundary (SAB). Sedimentologically, the Plavno sequence is interpreted as having been deposited on an extensive epeiric ramp under long-term transgressive conditions, sharing depositional characteristics of both the epeiric platform and the carbonate ramp. The entire Plavno sequence was deposited above the storm-wave base and was storm influenced. Three informal members are differentiated: 1) the dolostone member (Early Griesbachian); 2) the siliciclastic member (red-coloured shale, siltstone, sandstone with oolitic/bioclastic grainstone intercalations), which can be further divided into lower, middle and upper intervals (Late Griesbachian, Dienerian and Smithian); and 3) the mudstone member (grey lime mudstones, marls and calcisiltites with common ammonoids and gastropods-Spathian). The Plavno sequence is compared with other western Tethyan sections. Observed differences stem from local controls on deposition in the overall shallow marine environment.

• Author: Dunja Aljinović; Micha Horacek; Leopold Krystyn; Sylvain Richoz; Tea Kolar-Jurkovšek; Duje Smirčić; Bogdan Jurkovšek
• Department/s: Lithosphere and Biosphere Science
• Publishing year: 2018-08-01
• Language: English
• Pages: 806-823
• Publication/Series: Journal of Earth Science
• Volume: 29
• Issue: 4
• Links: http://dx.doi.org/10.1007/s12583-018-0787-3
• Document type: Journal article
• Publisher: Springer
• Topic: Geology
• Keywords: Dinarides; Early Triassic; epeiricramp; litho- and biostratigraphy; δC isotope curve
• Status: Published
• ISBN/ISSN/Other: ISSN: 1674-487X