Koleva-Rekalova, E., Metodiev, L., Ivanova, D. (2007) Documentation and correlation of
transgressive-regressive cycles from three Lower-Middle Jurassic successions of the Western
Balkan Mts, Bulgaria// Geologica Balc., V.36, no.3-4. P.91-96. Pdf: http://www.geology.bas.bg/geolbal/12_Koleva.pdf
The transgressive-regressive character and cyclic patterns of the European Jurassic rocks are topics of long-standing interest and debates. As a contrast, in Bulgarian geological literature there is a small number of publications concerning sequence stratigraphy and transgressive-regressive cyclicity of the Jurassic sediments. The main objective of the present study is to document the transgressive-regressive cyclic recurrence of three Lower-Middle Jurassic sections, exposed near the villages of Beledie Han and Breze (Western Balkan, Bulgaria). Fore thirdorder coarsening and shallowing upward transgressive-regressive cycles are recognized on the base of detailed sedimentlogical investigations and dated by precise ammonite zonation which is supplemented by foraminiferal data. It is evidenced that these depositional cycles build up the regressive phase (numbered R6, in accordance with other European basins) of a second order transgressive-regressive facies cycle. This investigation of cyclic character of the studied sections shows that sedimentation during the Toarcian and Early-Mid Aalenian time was formed under conditions of gradual regression of the sea basin.
