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The Benkovac Stone Member of the Promina Formation: A Late Eocene Succession of Storm-Dominated Shelf Deposits

E. Mrinjek
V. Pencinger
J. Sremac
B. Lukšić

Puni tekst: engleski, pdf (3 MB) str. 163-184 preuzimanja: 759* citiraj
APA 6th Edition
Mrinjek, E., Pencinger, V., Sremac, J. i Lukšić, B. (2005). The Benkovac Stone Member of the Promina Formation: A Late Eocene Succession of Storm-Dominated Shelf Deposits. Geologia Croatica, 58 (2), 163-184. Preuzeto s https://hrcak.srce.hr/3654
MLA 8th Edition
Mrinjek, E., et al. "The Benkovac Stone Member of the Promina Formation: A Late Eocene Succession of Storm-Dominated Shelf Deposits." Geologia Croatica, vol. 58, br. 2, 2005, str. 163-184. https://hrcak.srce.hr/3654. Citirano 20.06.2021.
Chicago 17th Edition
Mrinjek, E., V. Pencinger, J. Sremac i B. Lukšić. "The Benkovac Stone Member of the Promina Formation: A Late Eocene Succession of Storm-Dominated Shelf Deposits." Geologia Croatica 58, br. 2 (2005): 163-184. https://hrcak.srce.hr/3654
Harvard
Mrinjek, E., et al. (2005). 'The Benkovac Stone Member of the Promina Formation: A Late Eocene Succession of Storm-Dominated Shelf Deposits', Geologia Croatica, 58(2), str. 163-184. Preuzeto s: https://hrcak.srce.hr/3654 (Datum pristupa: 20.06.2021.)
Vancouver
Mrinjek E, Pencinger V, Sremac J, Lukšić B. The Benkovac Stone Member of the Promina Formation: A Late Eocene Succession of Storm-Dominated Shelf Deposits. Geologia Croatica [Internet]. 2005 [pristupljeno 20.06.2021.];58(2):163-184. Dostupno na: https://hrcak.srce.hr/3654
IEEE
E. Mrinjek, V. Pencinger, J. Sremac i B. Lukšić, "The Benkovac Stone Member of the Promina Formation: A Late Eocene Succession of Storm-Dominated Shelf Deposits", Geologia Croatica, vol.58, br. 2, str. 163-184, 2005. [Online]. Dostupno na: https://hrcak.srce.hr/3654. [Citirano: 20.06.2021.]

Sažetak
The Late Eocene Benkovac Stone Member of the Promina Formation of northern Dalmatia, Croatia, is a thinly bedded succession of alternating carbonate sandstones and calcareous mudstones, ca. 40 m thick, exposed as a narrow, SE-trending outcrop belt near the town of Benkovac. This unit occurs in the middle part of the Promina Formation, which is a spectacular calciclastic succession of deposits of late Middle Eocene to Early Oligocene age, about 2000 m thick, showing an upward trasition from deep-marine turbidites to shallow-marine and alluvial deposits.

The sheet-like sandstone beds of the Benkovac Stone Member are mainly 1–25 cm thick and have been classified into 6 facies and 3 subfacies, differing in stratification or showing various internal sequences of stratification types. The thicker and most common beds show plane-parallel stratification passing upward into hummocky cross-lamination and undulatory to flat parallel lamination (Facies S1), or consist of only the latter two divisions (Facies S2). Subordinate beds show convolute stratification (Facies S3), are amalgamated (Facies S4), or are homogenized and merely graded (Facies S6). The thinner beds have more uneven boundaries and show translatory ripple cross-lamination (Subfacies S5a), climbing ripple cross-lamination (Subfacies S5b) or pinch-and-swell lamination attributed to starved and rolling-grain ripples (Subfacies S5c). The intervening mudstone beds (Facies M) are silt-streaked and bioturbated. Trace fossils indicate a combination of Zoophycos and Cruziana ichnofacies.

The sedimentary succession was deposited in a microtidal offshore transition zone characterized by muddy “background” sedimentation punctuated by discrete storm events. The observed spectrum of tempestite sandstone beds represents a wide range of storm events, varying in magnitude and in the mode of sand dispersal – from the pure action of oscillatory waves to pure geostrophic currents. The majority of tempestites are attributed to a combination of these two end-member factors, with the geostrophic currents often enhanced by a high load of sediment suspension (density-modified currents).

The Benkovac Stone Member is underlain by muddy offshore deposits (Debelo Brdo Member) and covered by sandy to gravelly shoreface deposits (Otavac Member), which in turn pass upwards into braidplain deltaic and alluvial deposits. This regressive succession is considered to be a parasequence deposited as a highstand systems tract during a gradual, stepwise rise of relative sea level. The thick parasequence consists of progradational and retrogradational sets of much smaller parasequences, the record of which differs markedly in the shoreface and offshore transitional part. The difference is attributed to the underlying contrast in the physical factors controlling the supply of sand to these shallow shelf zones.

Ključne riječi
Shelf; Shoreface; Offshore transition zone; Tempestites; Hummocky cross-lamination; Wave ripples; Oscillatory waves; Combined-flow currents; Trace fossils; Braidplain delta; Sequence stratigraphy; Northern Dalmatia; Croatia

Hrčak ID: 3654

URI
https://hrcak.srce.hr/3654

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