Naslov
Upper Jurassic and Cretaceous peritidal, lagoonal, shallow marine and perireefal Sediments of Istria

Autori
Tišljar, Josip ; Velić, Ivo ; Radovčić, Jokov ; Crnković, Branko

Vrsta, podvrsta i kategorija rada
Poglavlja u knjigama, znanstveni

Knjiga
CONTRIBUTION TO SEDIMENTOLOGY OF SAME CARBONATE AND CLASTIC UNITS OF THE COASTAL DINARIDES

Urednik/ci
Babić, Ljubo ; Jelaska, Vladimir

Izdavač
International Association of Sedimentologists (IAS)

Grad
Split

Godina
1983

Raspon stranica
79-85

Ključne riječi
carbonate sediments, early-diagenetic dolomites, LLH-stromatolite, peritidal, lagonal-shallow marine environments, Upper Jurassic, Cretaceous, Istria, Croatia

Sažetak
The Upper Jurassic and Cretaceous sediments in western and southern Istria are shallow-marine carbonates deposited onto a vast carbonate platform in a supratidal, intertidal, subtidal, lagoonalm back reef and perireefal environments.Early-diagenetic dolomites without traces of evaporites, formed by early-diagenetic dolomitization of supratidal carbonate muds under relatively humid climate have been found only in the Berriasian succession of western Istria.In the Lower Cretaceous most frequent are shallowing-upward cycles composed of pelletal or skeletal wackestones and LLH-stromatolites with fenestral fabric and desiccation cracks within mudstone laminae. Lagoonal limestones are mostly micritic rocks consisting predominantly of carbonate mud, i.e. micrite, and algal oncoids, faecal pellets, peloids and skelets and/or bioclasts of restricted marine flora and fauna: green-algae (especially Salpingoporella dinarica), gastropods, ostracods and micritized benthic foraminifera - primarily palorbitolinas and mesorbitolinas. Within the Upper Albian inner platform lagoonal and shallow subtidal oncoid and peloidal mud-bearing limestones very characteristic is occurrence of “ quartz diagenetic sediments” .The origin of “ Quartz sediments” is probably connected with processes of early-diagenetic silicification of carbonate sediments, caused by aeolian input of very fine volcanic ash mixed with carbonates, which was gradually dissolved in restricted alcalic lagoonal environments.Alternations of rudist coquinas and thinner or thicker rudist biostromes and/or thickets with rudist shells in life position are common, and in some localities even predominant lithology, in the Cenomanian of southern Istria. On the Fenoliga islet limestone are represened by exposure of several meters thick rudist coquinas and biostromes and especially with numerous dinosaur footprints.

Izvorni jezik
Engleski

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