Ruggero Matteucci

Recent foraminiferal assemblages from mixed carbonate-siliciclastic sediments of southern Somalia and eastern Kenya

A total of 256 recent benthic foraminiferal species belonging to 111 genera is identified from 73 carbonate-siliciclastic sedimen samples collected along the coast of southern Somalia (Burgao channel) and eastern Kenya (Lamu Archipelago). This represents the first survey of recent foraminifers in this region of East Africa. The sediment samples are representative of different environments (e.g., mangrove flats, tidal channels, restricted shelf, and open shelf), water depths (0-60 m), and salinities (strongly brackish to normal marine conditions). Q-mode Hierarchical Cluster Analysis reveals that nine assemblages can be distinguished; for each assemblage, faunal composition and distribution, diversity indices and dominance are assessed. As predicted by ecological models, there is an overall trend of increasing species diversity from the backwater zone within channels to open marine conditions, and from intertidal to subtidal settings. Salinity, suspended sediment, nutrient levels, and tidal exposure are the most influential factors in determining benthic foraminiferal distribution patterns. An interesting feature is the nearshore contraction of the depth gradient determining the shallower distribution of several larger foraminiferal species, as evidenced by the depth ranges of five species of Amphistegina

Recent coral facies of the Indian Ocean Coast of Somalia with an interim check list of corals

SummaryFrom a study of two areas, Jesira and the Bajuni Archipelago, about 400 km apart, a general pattern can be established for the Recent facies, together with the morphological and taxonomic features of the corals. Present day coral development is characterized by true fringing reefs in the Bajuni Archipelago and by scattered patches and knolls in the Jesira area. The coral fauna, consisting of 27 genera and 63 species so far (including all uncertainties, but not sight records), is rather poor, though coral communities are locally well developed. These figures probably reflect incomplete study and sampling. Although comparison with other areas may therefore be premature, a preliminary biogeographical analysis suggests that this fauna is more closely related to that of the Red Sea than to East Africa and the Seychelles. This differs from other published biogeographical work on Indian Ocean coral faunas, but further study of the corals in this and neighbouring areas of the Indian Ocean is needed in order to resolve this apparent anomaly.

The Middle Eocene siliceous sponges from Val di Chiampo (Lessini Mountains, northern Italy)

The Lower Lutetian hyaloclastites cropping out in the Val di Chiampo (Vicenza, northern Italy) contain a very rich and diversified siliceous sponge fauna. In this paper we give preliminary determinations and illustrations of 23 siliceous sponge species. The most abundant are the Lychniscosa, with ten species, followed by Hexactinosa, with seven species, and Lithistida, with six species. Twelve species are in open nomenclature, five are identical or similar to species described by Pisera and Busquets (2002), from the Bartonian of the Ebro Basin (Spain), and five are compared with species described by Pomel (1872) from the Miocene of Algeria. From a paleoecological point of view, it is supposed that the sponge fauna inhabited the euphotic zone.

The Italian Cenozoic siliceous sponges: a review, with a revision of the Catullo (1856) collection

ABSTRACT - Siliceous sponges are known from Eocene, Miocene and Pliocene levels in Italy, but they are poorly investigated. The taxa recognized or erected by authors of the second half of the nineteenth century (T.A. Catullo, A. Manzoni, P. Malfatti) are listed and discussed. The geographical, geological and paleoenvironmental knowledge about the marine levels bearing their rigid skeletal bodies are reviewed. For most of these deposits, the presence of a volcanoclastic input has been evidenced. All the examined original specimens of Catullo’s (1856) siliceous sponge collection, stored at the Geological and Paleontological Museum of University of Padua, are recognized as non referable to siliceous sponges.

Paleocene palustrine and ephemeral alluvial facies in southern Sardinia (Italy)

Paleocene ephemeral alluvial and palustrine deposits have been recognized in several small outcrops in southern Sardinia. Three sedimentary units have been distinguished: the basal one, mainly terrigenous, made up of alluvial pedogenized deposits, the intermediate one, entirely carbonate, made up of pedogenized fresh water deposits, and the third one, terrigenous-carbonate, recording the beginning of the Thanetian marine ingression in Sardinia. The carbonate deposits are the most developed and are mainly characterized by the presence of Microcodium, both with corn-cob aggregates, in some cases forming palisades or reef-like buildups, and with disarticulated grains forming resedimented deposits; charophyte stems and gyrogonites and stromatolites are also present, in some cases frequent. Deposits rich in charophyte stems indicate the presence of perennial water ponds. Alternances of humid and dry periods favoured erosive fluctuations, as indicated by the frequence of resedimented intraclasts of fresh water sediments, biotic remains as charophytes and stromatolites and, over all, detrital disaggregated Microcodium grains. The studied small outcrops are the only remnants of a probably wide Paleocene continental sedimentary cover, and provide informations on a variety of depositional facies, which are useful proxies for depicting a landscape with wetlands and detrital Microcodium deposits, similar to the coheval continental landscape widespread in southern France and in northeastern Spain.