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2019 (vol. 19)

New stratigraphic and genetic model for the dolomitic Cretaceous Pinda reservoirs in Angola. Part II - Compelling arguments against early dolomitization and early leaching

 | HTML  | PDF [3,099 KB]  | DOI : 10.4267/2042/69773

 Abstract:  This is the second contribution to the stratigraphic and genetic model of the Pinda Group. The mid-Cretaceous Pinda Group of the Congo basin in the northern Angolan offshore is a transgressive supersequence. Its lower part is made of Bufalo and Pacassa facies that correspond respectively to mixed and calcareous-dolomitic grain-dominated fabrics. Both facies were strongly diagenetically altered, mostly by dolomitic replacement and leaching. Contrary to opinions expressed by other authors that both styles of alteration are early diagenetic phenomena, there is substantial evidence for a burial origin with dolomitic replacement and leaching of calcite having started at depths not less than 150 m and 400 m, respectively.

Carnets Geol., vol. 19, no. 4, p. 47-70

Online since February 15, 2019

The "avatars" of Triloculina laevigata Orbigny, 1826, generic and specific attribution

 | HTML  | PDF [1,280 KB]  | DOI : 10.4267/2042/69756

 Abstract:  The purpose of this study is to clarify the problem posed by Triloculina laevigata Orbigny, 1826, nom. nud., described and figured by Fornasini in 1905. An other species, also called Triloculina laevigata was created by Bornemann in 1855 and Orbigny's specific name became invalid. This invalidity was only recently assessed and numerous authors still use the original assignation. Consequently, it seems necessary to erect a new name. After listing the various names, revising the subgenus and genera attributed to Triloculina laevigata, and comparing fossil and recent specimens, the name: Affinetrina alcidi Lévy et al., 1992a, is confirmed.

Carnets Geol., vol. 19, no. 3, p. 35-46

Online since February 4, 2019

Uteria naghanensis n. sp. (Dasycladale) from the Upper Maastrichtian of Iran

 | HTML  | PDF [1,498 KB]  | DOI : 10.4267/2042/69755

 Abstract:  A new dasycladalean alga is described as Uteria naghanensis n. sp. from the late Maastrichtian Tarbur Formation of the Zagros Zone, SW Iran. It is a small to medium-sized, rather well calcified species with small articles each bearing one fertile ampulla, alternating with close-set verticils of numerous sterile laterals. Another characteristic is its comparably wide main axis. The genus Uteria Michelin was so far only known from the Paleogene (Danian-Lutetian). The discovery of U. naghanensis n. sp. in inner platform wackestone of the Tarbur Fm. documents the origination of the genus already in the uppermost Cretaceous within an area belonging to the Arabian Plate.

Carnets Geol., vol. 19, no. 2, p. 21-33

Online since February 3, 2019

Reinstatement of the genus Bakalovaella Bucur, 1993 (Dasycladeae, Dasycladaceae), and a description of its earliest Cretaceous representative
Bruno R.C. GRANIER & Ioan I. BUCUR

 | HTML  | PDF [3,082 KB]  | DOI : 10.4267/2042/69540

 Abstract:  A new Dasycladacean species found in Hauterivian strata in Aquitaine is described. It is ascribed to the genus Bakalovaella Bucur, 1993, which is reinstated here. From a phylogenetic point of view, based of the "lifting piston" model, this taxon should be part of a lineage derived from the Diploporaceae.

Carnets Geol., vol. 19, no. 1, p. 1-19

Online since January 17, 2019

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