Wyniki wyszukiwania - BazTech

Ograniczanie wyników

1 Volumina Jurassica

1 2006

Znaleziono wyników: 1

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: platform to basin transition

Sortuj według:

Ogranicz wyniki do:

Upper Jurassic - Lower Cretaceous platform to basin transition of the Northern Calcareous Alps

Fenninger A., Rasser M.

Volumina Jurassica

2006

Vol. 4, no. 1

87-87

Tectonic events in the Upper Triassic caused the break of carbonate platforms in the Northern Calcareous Alps (NCA). Drawning and synsedimentary faulting stipulated a highly structured seaflor topography with sedimentation of crinoidal limestones, cherty limestones as well as cephalopod limestones on top of the Triassic platforms. This mainly pelagic development lasted until the Oxfordian with deposition of radiolarites and siliceous limestones. The Upper Jurassic to Lower Cretaceous development is linked to the opening of the Northern Atlantic and the Penninic Ocean and led to the break up of Pangea and the Austroalpine units. They became independent from the European Plate and are considered as microplate north of the Apulian Plate. Basin sediments of the central part of the NCA are represented by radiolarites and cherty limestones overlain by Tithonian to Valangian micritic sediments with intercalations of allodapic limestones. Carbonate breccias together with variagated nodular limestones and periplatform ooze are interpreted as slope deposits. Platform environments are represented by large carbonate mud areas with local patch reefs. Other reefal areas of the platform are dominated by "stromatoporids", "chaetedids", scleractinians and microincrusters binding reef rubble. Inner platform environments are dominated by "stromatoporids" while corals are subordinate. In open platform environments secondary framework builders can bind reef rubble. The Jurassic Alpine reefs reflect trends to coral adapted oligotrophic high-energy conditions, representing ancestors of modern reefs. Beside the typical reef guild organisms, gastropods (nerineids) and patches of dasycladales are typical for low energy environments.