Biostratigraphy and palaeoenvironmental development of the Callovian-Valanginian carbonate platform from the Lyubash unit (SW Bulgaria)

• Autorzy: Ivanova, D. , Koleva-Rekalova, El , Kołodziej, B. , Metodiev, L. , Roniewicz, E.
• Konferencja: International Congress on the Jurassic System (7 ; 06-18.09.2006 ; Kraków, Poland)
• Języki publikacji: PL

Abstrakty

EN

This study deals with the successions located in the Lyubash unit (SW Bulgaria), which represents a part of the Moesian Carbonate Platform in Middle Jurassic – Early Cretaceous time interval. According to the recent tectonic scheme of Bulgaria (Dabovski et al. 2002) the Lyubash unit belongs to Srednogorie tectonic zone of the Balkan orogenic system. Three sections have been sampled and studied – Rebro, Lyalintsi and Velinovo, which are built up by thick-bedded to massive light grey to whitish organogenic and micritic limestones of the Javorets, Gintsi and Slivnitsa formations. Detailed studies on foraminifera and calcareous dinocyst, provided new biostratigraphic data, and confirmed the Middle Callovian-Valanginian age of the examined sediments as assumed previously by Sapunov et al. (1985). Foraminifera are particularly abundant in the lagoon facies, and represented by genera: Globuligerina, Ophthalmidium, Cornuspira, Ammobaculites, Mesoendothyra, Labyrinthina, Kurnubia, Pseudocyclammina, Dobrogelina, Rumanoloculina, Hechtina, Meandrospira, Valvulina, Trocholina, and Neotrocholina. The sedimentological analysis allowed recognizing microfacies groups assigned to three facies zones: platform slope facies, reef and peri-reef facies and lagoon-tidal flat facies. The development of the platform is characterized by complex vertical and lateral alternation of the studied microfacies. Platform slope facies are prevalent at the section Rebro; the Lyalintsi section is dominated by reef and peri-reef facies, and the section Velinovo is mainly dominated by lagoon facies. Sea-level fluctuations are observed, however generally, a shallowing-upward trend in the platform evolution is observed in all three sections. Coral-microbial reefs are developed as biostromes, and contain numerous and highly differentiated scleractinian corals: 70 species (6 new) from 50 genera (4 new). Among them following corals are the most common: phacelloid Latomeandra, Stylosmilia, Thecosmilia, Cladophyllia, ramose Solenocoenia, Meandrophyllia, lameller Synastraea and Microsolena. Reef development has been disturbed by sea level rise, evidenced by limestones with Saccocoma, intercalated with coral biostromes.

Słowa kluczowe

EN

Callovian; Valanginian; carbonate platform; biostratigraphy; Lyubash unit; SW Bulgaria; palaeoenvironmental development

• Czasopismo: Volumina Jurassica
• Rocznik: 2006
• Tom: Vol. 4, no. 1
• Strony: 174-175
• Opis fizyczny: Bibliogr. 2 poz.

Twórcy

autor

Ivanova, D.

autor

Koleva-Rekalova, El

autor

Kołodziej, B.

autor

Metodiev, L.

autor

Roniewicz, E.

• Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria,

Bibliografia

• Dabovski C., Boyanov I., Khrischev Kh., Nikolov T., Sapunov I., Yanev Y. and Zagorchev I. 2002. Structure and Alpine evolution of Bulgaria. Geologica Balcanica, 32, 2-4: 9-15.
• Sapunov I., Tchoumatchenco P., Dodekova L. and Bakalova D. 1985. Stratigraphy of the Callovian and Upper Jurassic rocks in Southwestern Bulgaria. Geologica Balcanica, 15, 2: 3-61.