engleski

Jurassic carbonate succession of Gorski kotar (Western Dinarides - Croatia) as sedimentary reflection of geodynamics within the Peritethyian region

The shallow-water carbonate succession of Gorski kotar (Western Dinarides - Croatia) contains typical sedimentary signature of Jurassic inner Adriatic carbonate platform depositional events. During the most of the Early Jurassic, deposition was characterized by the periodic sea-bottom oscillations around the fair-weather wave-base when successive series of autocycles were formed. As these environmental conditions existed throughout the platform, the uniformity of sedimentary events and their apparently simultaneous alternation took place. From the late Early Jurassic till the end of the early Late Jurassic, platform sedimentary environments experienced a slight deepening, when micritic limestones were predominantly produced in great amount all over the platform. They were sporadically and irregularly intercalated with the coarser-grained intercalations of varying structure and thickness as a consequence of sporadic storms and/or higher tides that triggered progradations from the neighboring topographic highs, characterized with more favorable ecological conditions for abundant inhabitance of various organisms. This longterm micritic dominated sedimentary interval was a reflection of geodynamics within the Peritethyian region, caused by opening of the Dinaridic branch of the Tethys on the NE side of the Adriatic carbonate platform, and the opening of the Adriatic basin on the S-SW side of it. Namely, this extensional events at both platform sides caused slight and steady deepening of the Adriatic platform interior, with predominant carbonate deposition within the subtidal below-the fair-weather wave-base when predominant micritic-rich limestones originated. The establishment of long-lasting peritidal conditions observed within the late Upper Jurassic part of the succession, indicate the shallowing of the Adriatic platform realm. This was a consequence of advanced NE platform margin shifting towards the S-SW, which triggered simultaneous and gradual uplift of S-SW platform margin. This uplifting stopped when further shifting at the NE Adriatic carbonate platform margin stopped, i.e. at the end of the Late Jurassic when closing of the Dinaridic branch of the Tethys began. This led to predominance of a slight subsidence rate within the sedimentary environment that, combined with global eustatic sea-level rise, enabled the pronounced drowning of the S-SW Adriatic platform margin as well as the inner platform area during the transition from the Late Jurassic to the Early Cretaceous.

Jurasic; carbonate succession; Gorski kotar; geodynamics; Peritethyian region

nije evidentirano