20.500.12556/DiRROS-16014-218740a5-debe-66f9-ce7a-28b2ab3b3ae5 A glimpse of the lost Upper Triassic to Middle Jurassic architecture of the Dinaric Carbonate Platform margin and slope Pogled v izgubljeno zgornjetriasno in spodnjejursko arhitekturo pobočja in roba Dinarske karbonatne platforme In the southernmost outcrops of the Slovenian Basin the Middle Jurassic coarse-grained limestone breccia (mega)beds are interstratified within a succession that is otherwise dominated by hemipelagites and distal turbidites. In this paper, these beds are described as the Ponikve Breccia Member of the Tolmin Formation. We provide descriptions of the studied sections with detailed geological maps and analysis of the breccia lithoclasts. From the latter, a non-outcropping margin of the Dinaric Carbonate Platform is reconstructed. In the Late Triassic the platform margin was characterized by a Dachstein-type marginal reef. After the end-Triassic extinction event, the platform architecture remained, but the reefs were replaced by sand shoals characterized by ooids. In the late Early Jurassic and/or early Middle Jurassic a slope area might have been dissected by normal faults and a step-like paleotopography was formed. In the Bajocian, during a period of major regional geodynamic perturbations, extensional or transtensional tectonic activity intensified and triggered the large-scale collapses of the Dinaric Carbonate Platform margin producing the limestone breccias described herein. This may in turn have caused a backstepping of the platform margin, as is evident from the occurrence of Late Jurassic marginal reefs that are installed directly above the Upper Triassic and Lower Jurassic inner platform successions. V najjužnejših izdankih Slovenskega bazena se znotraj zaporedja, v katerem sicer prevladujejo hemipelagične kamnine in distalni turbiditi, pojavljajo (vele)plasti srednjejurske debelozrnate apnenčeve breče. V prispevku so te plasti opisane kot Ponikvanska breča in sicer kot člen Tolminske formacije. V opisu podajamo podroben opis proučenih profilov, vključujoč detajlne geološke karte in analizo litoklastov v breči. Iz slednjega je bilo možno rekonstruirati danes nerazgaljeni rob Dinarske karbonatne platforme. V poznem triasu je bil zanj značilen dachsteinski tip obrobnega grebena. Po triasno-jurskem izumrtju je arhitektura platforme sicer ostala enaka, vendar so grebene nadomestile peščene plitvine, za katere so značilni ooidi. V pozni spodnji juri in/ali zgodnji srednji juri je bilo območje pobočja razčlenjeno najverjetneje z normalnimi prelomi in nastala je stopničasta paleotopografija. V bajociju se je v času velikih regionalnih geodinamskih sprememb okrepila ekstenzijska ali transtenzijska tektonska aktivnost, ki je sprožila obsežne porušitve robnega dela Dinarske karbonatne platforme in nastale so tukaj opisane apnenčaste breče. To bi lahko povzročilo umik roba platforme, kar je razvidno iz pozicije zgornjejurskih obrobnih grebenov, ki se pojavljajo neposredno nad zgornjetriasnim in spodnjejurskim zaporedjem notranjega dela platforme. Slovenian Basin Dinaric Carbonate Platform Middle Jurassic limestone breccia debris-flow stratigraphy Ponikve breccia Slovenski bazen Dinarska karbonatna platforma srednja jura apnenčaste breče drobirski tok stratigrafija Ponikvanska breča true false true Geološki zavod Slovenije Angleški jezik Slovenski jezik © Author(s) 2022. Neznano 2023-01-06 03:34:53 2023-01-18 08:53:54 2023-03-02 08:05:51 0000-00-00 00:00:00 2022 0 0 str. 177-216 no. 2 vol. 65 2022 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 2022-12-21 551.7:552.511"622.44" 0016-7789 10.5474/geologija.2022.011 135317763 https://www.geologija-revija.si/index.php/geologija/article/view/1843/1908 1 42b89ca3-9705-11ed-b359-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=21372 1843-Article_Text-12342416-1-10-20221221-1.pdf 1843-Article_Text-12342416-1-10-20221221-1.pdf 1 AC42F9F76EBF76222F8E230257D66D31 48416bd3dd0921bee05cb82d6447cefe4b8e5fe4af0dff3e75c38eb8f4c47e93 acf25292-9710-11ed-b359-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=21385 Geološki zavod Slovenije Institut Jožef Stefan Zavod za gradbeništvo Slovenije Geologija 0 0 0