Ternate Formation, a late Eocene bioclastic submarine fan of the Lombardian basin (southern Alps)

Conference · Mon Aug 01 04:00:00 EDT 1988 · AAPG Bull.; (United States)

OSTI ID:5694492

Bernoulli, D; Herb, R; Gruenig, A

The Ternate Formation consists of some 150 m of redeposited bioclastic limestones, channelized rubble beds, and pebbly mudstones and subordinate hemipelagic marls with a late Eocene fauna of planktonic Foraminifera (Globorotalia cerroazulensis cerroazulensis Zone). Parallel-bedded massive or graded bioclastic limestones are overlain by channelized deposits. Large channels are up to 12 m deep; some contain pebbly mudstones with large slabs and boulders of older marls and limestones in a matrix of middle Eocene marls. More typically, the channels are filled by pebbly calcirudites grading into calcarenites and laterally wedging out over very short distances. Interchannel deposits are thin-bedded, graded calcarenites and thin green marls. The bioclastic limestones contain mainly coralline algae, larger Foraminifera (nummulitids, Discocyclina), bryozoans, echinoderms, and other shallow-water biota. All lithic fragments are of local, south-Alpine origin. By far the most abundant are spiculitic limestones and marls of Liassic age and Upper Cretaceous to middle Eocene limestones and marls. Most of the redeposited calcareous sand and gravel was deposited in ephemeral channels which cut across each other in a very complex way and were briefly active. This depositional system matches the suprafan environment of a prograding submarine fan of low transport efficiency. The facies of the conglomerates, the local source of the lithic fragments, and comparison with other lower Tertiary bioclastic deep-water deposits suggest short transport and deposition in one (or a series) of local bioclastic submarine fans. The benthic Foraminifera associated with the hemipelagic marls indicate deposition in the upper bathyal zone (600-1,000 m).

• Research Organization: ETH-Zentrum, Zuerich (Switzerland)
• OSTI ID: 5694492
• Report Number(s): CONF-8809346-
• Conference Information: Journal Name: AAPG Bull.; (United States) Journal Volume: 72:8
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
ALGAE
ALLUVIAL DEPOSITS
ALPS
ANIMALS
CARBONATE ROCKS
CENOZOIC ERA
CRETACEOUS PERIOD
DEPOSITION
EOCENE EPOCH
EUROPE
FORAMINIFERA
GEOLOGIC AGES
GEOLOGIC DEPOSITS
INVERTEBRATES
LIMESTONE
MESOZOIC ERA
MICROORGANISMS
MOUNTAINS
PLANTS
PROTOZOA
ROCKS
SARCODINA
SEDIMENTARY ROCKS
SWITZERLAND
TERTIARY PERIOD
WESTERN EUROPE