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

作　　者：Dunja Aljinovic Micha Horacek Leopold Krystyn Sylvain Richoz Tea Kolar-Jurkovsek Duje Smircic Bogdan Jurkovsek 

机构地区：[1]University of Zagreb, Faculty of Mining, Geology and Petroleum Engineering, Pierottijeva 6, Zagreb 10000, Croatia [2]BLT Wieselburg, HBLFA Francisco-Josephinum, Rottenhauserstr. 1, Wieselburg 3250, Austria [3]Institute of Paleontology, Vienna University, A lthanstrafle 14, Vienna 1090, Austria [4]Lund University, Lithosphere and Biosphere science, Solvegatan 12, Lund 22362, Sweden [5]Geological Survey of Slovenia, Dimiceva Ulica 14, Ljubljana 1000, Slovenia

出　　处：《Journal of Earth Science》2018年第4期806-823,共18页地球科学学刊（英文版）

基　　金：part of the Austrian-Croatian Bilateral Project (No. 2014-15) supported by OeAD;the Austrian Agency for International Mobility and Cooperation in Education;the Croatian Ministry of Science, Education and Sport;partly supported by the Slovenian Research Agency (No. P1-0011)

摘　　要：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 613C curve is consistent with former studies. It displays a general increase from the Griesbachian to a prominent maximum beyond the ＋8%0 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 silicielastic member （red-coloured shale, siltstone, sandstone with oolitic/bioclastie 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.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 613C curve is consistent with former studies. It displays a general increase from the Griesbachian to a prominent maximum beyond the ＋8%0 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 silicielastic member （red-coloured shale, siltstone, sandstone with oolitic/bioclastie 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.

关 键 词：Early Triassic DINARIDES epeiric ramp 6Z3C isotope curve litho- and biostratigraphy. 

分 类 号：P318.4[天文地球—固体地球物理学] TH112[天文地球—地球物理学]