Johannes Pignatti

Extreme sulphur isotope fractionation in the deep Cretaceous biosphere

Abstract: Isotopically light sulphur in sedimentary pyrite was generally predominant during the Cretaceous as a consequence of volcanic and hydrothermal activity and bacterial sulphate reduction (BSR). However, we report super-high sulphur isotopic compositions of sedimentary pyrite (δ34S +89.3‰) from late mid-Cretaceous sediments from the Central Apennines, Italy. These exceptionally high δ34S values are not consistent with current models for interpreting the geological record for sulphur isotopes because these cannot explain the extreme isotopic fractionation observed in our study. Precise details of the mechanism for producing pyrite so highly enriched in 34S remain elusive, but the large variation in δ34S values (>70‰) within the analysed samples and the considerable micro-scale variations in δ34S (up to 50‰ even within a single nodule) indicate a complex mechanism of sulphate reduction and pyrite precipitation. This includes early removal of isotopically light H2S by pyrite precipitation in the water column, diffusion and advection of H2S and SO42−, and finally BSR. Similar but less severe conditions occur in the Black Sea and in deep ocean sediments. These new findings provide new insights for the interpretation of the palaeoceanographic conditions that prevailed during the Mesozoic.

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

Conflicting evolutionary and biostratigraphical trends in Nephrolepidina praemarginata (Douvillé, 1908) (Foraminiferida)

Six late Rupelian populations of Nephrolepidina praemarginata (Douvillé, 1908) have been isolated from a succession of the Caltavuturo Formation (Madonie Mts, Sicily). A total of 25 embryonal parameters were obtained from oriented equatorial sections of megalospheric specimens; 8 indexes were derived from selected parameters and 9 indexes were considered for the neanic apparatus, out of which 2 are introduced here: N05 (number of annuli in a radius of 0.5 mm) and r5 (distance occupied by the first five annuli). The data show marked deviations from the expected trend of traditional biometric measures; this is interpreted as dependent on environmental factors. Previous studies on the succession evidenced an increase in basin depth; this can be inferred also from the biometric analysis of the inner characters of the allochthonous Nephrolepidina tests. Here, we explore the paleobiological potential of parameters linked to embryo size and wall thickness, and discuss how depth-dependent parameters may affect the interpretation of evolutionary trends and biostratigraphy in radial foraminifers.

Heterostegina matteuccii sp. nov. (Foraminiferida: Nummulitidae) from the lower Oligocene of Sicily and Aquitaine: a possible transatlantic immigrant

The systematics and phylogenetic relations of the Oligocene species of Heterostegina (Nummulitidae) are poorly known compared to those of Eocene and Miocene species. The new species Heterostegina matteuccii sp. nov., characterized by the combination of an advanced nepionic stage (i.e. very few operculine chambers) and a relatively small proloculus, is here described from the lower Oligocene Caltavuturo Formation of Portella Colla (Madonie Mts, Sicily, Italy). The same species is recorded also in the ‘Calcaire à astéries’ Formation of Illats (Northern Aquitaine, near Bordeaux, France). Biometrically, H. matteuccii sp. nov. does not fit within any known Neo-Tethyan lineage of Heterostegina from the Eocene to the Miocene, and hence is considered to be a member of a distinct phyletic lineage. The advanced nepionic stage of H. matteuccii sp. nov., however, calls for the existence of predecessors. The Priabonian (and possibly also earliest Oligocene) H. ocalana Cushman, 1921 from the American-Caribbean realm is here interpreted as the most probable ancestral form for the H. matteuccii lineage. Thus, an early Oligocene eastward transatlantic migration of this lineage may be inferred. New results of strontium isotope stratigraphy from both sides of the Atlantic Ocean are consistent with this hypothesis. http://zoobank.org/urn:lsid:zoobank.org:pub:CC54DB64-091D-4CDE-A6AB-6DC620F0FC23

Microfacies analysis of deep-water breccia clasts: a tool for interpreting shallow- vs. deep-ramp Paleogene sedimentation in Cephalonia and Zakynthos (Ionian Islands, Greece)

The tectono-sedimentary evolution of the western Pre-Apulian zone of the Hellenides is investigated through comparison of the microfacies of clasts from breccia beds within gravity-flow successions of Zakynthos with those of the carbonate ramp of the westernmost part of Cephalonia. After the demise of a Late Cretaceous rimmed platform, the Paleogene successions of the Ionian Islands represent different facies patterns of a carbonate ramp. In western Cephalonia (Lixouri peninsula), different successions suggest the existence of five juxtaposed tectono-sedimentary sectors, remnants of a larger carbonate ramp. In Zakynthos, six distinct sectors with different toe of slope-proximal basin stratigraphic successions were recognized, all affected by a Paleocene-Lower Eocene hiatus, which can be grouped into two tectono-sedimentary units. Through the analysis of successions of the Lixouri peninsula and breccia clasts from Zakynthos, 24 age-constrained and spatially related Upper Cretaceous–Oligocene microfacies types were recognized, illustrating a variety of sedimentary environments. These microfacies were allocated to five different stages in the evolution of a tectono-sedimentary model from down-faulting, through backstepping, uplift and dismantling, to fault-controlled subsidence and finally complete drowning. Various microfacies of the clasts can be correlated to the stratigraphic record of the Lixouri peninsula, whereas others are absent there. Thus an inferred adjacent source terrain, now tectonically obliterated, was likely located west of the present-day Ionian Islands.

CAUDAMMINA GUTTA , A NEW SPECIES OF HORMOSINELLIDAE (FORAMINIFERIDA) FROM THE RUPELIAN OF SICILY (ITALY)

A new species of agglutinated foraminifer, Caudammina gutta n. sp., is described from Lower Oligocene (upper Rupelian) strata of the Caltavuturo Formation near Portella C olla in the Madonie Mts. (northern Sicily). The new species comes from assemblages rich in deep-water agglutinated foraminifers (DWAF). Biometrical data based on two populations of the new species are compared with the species currently referred to the genus Caudammina , as yet known from the Tithonian to the Middle Eocene. C. gutta n. sp. has a large-sized pyriform test and is the end-member of a Cretaceous-Paleogene lineage which is interpreted as an example of size increase in time conforming to Cope’s rule.

Bartonian orthophragminids with new endemic species from the Pirkoh and Drazinda formations in the Sulaiman Range, Indus Basin, Pakistan

Abstract The Pirkoh and Drazinda formations in the Sulaiman Range, central Pakistan, yielded assemblages of (early) Bartonian orthophragminids, characterized predominantly by discocyclinids with a significant number of species probably endemic to Indian Subcontinent. The rarity of Asterocyclina and the absence of Orbitoclypeus and Nemkovella are noteworthy. Ten species of Discocyclina Gümbel and two species of Asterocyclina Gümbel, referable to the Shallow Benthics Zone (SBZ) 17 are described for the first time from Pakistan. The discocyclinids, i.e. Discocyclina praeomphalus, D. sulaimanensis, D. kutchensis, along with the new taxa established here, D. zindapirensis sp. nov., D. rakhinalaensis sp. nov., and D. pseudodispansa sp. nov., seem to be confined to the Indo-Pakistani region (Eastern Tethys). The Discocyclina dispansa, D. discus, D. nandori, and D. augustae lineages known from Western Tethys are also common in the Indian Subcontinent, as are asterocyclinids, such as Asterocyclina sireli and A. stellata. The upper part of the Drazinda Formation (‘Pellatispira beds’), referable to latest Bartonian and/or the early Priabonian, is poor in orthophragminids and is characterized by the occurrence of reticulate Nummulites, Heterostegina, Pellatispira and Silvestriella. The records of ‘Lepidocyclina of Caribbean affinity’ with large embryons from the Eocene of the Indian Subcontinent correspond to misidentified Discocyclina discus.

The Xiphoteuthididae Bather, 1892 (Aulacocerida, Coleoidea)

Problems in the classification of the Xiphoteuthididae have been recently addressed (Mariotti and Pignatti, 1992, 1994, 1996; Pignatti and Mariotti, 1996), but a critical revision is still lacking, owing mainly to their incomplete fossil record. The following outline of a classification summarizes diagnostic characters, taxonomic relationships, and geological occurrences of the genera currently included in the family Xiphoteuthididae: Atractites Gumbel, 1861, Breviatractites Mariotti and Pignatti, 1992, Claviatractites Mariotti and Pignatti, 1996, Crassiatractites Mariotti and Pignatti, 1992, Delphinoteuthis Mariotti and Pignatti, 1994, Metabelemnites Flower, 1944, Choanoteuthis Fischer, 1951, and Calliconites Gemmellaro, 1904. The taxonomic status of Choanoteuthis and the supragen- eric attribution of Calliconites remain uncertain.

A Sculpted Dish from Tello Made of a Rare Stone (Louvre-AO 153)

A fragment of a sculpted stone dish from Tello (ancient Ĝirsu), which was found in the early excavations directed by Ernest de Sarzec, has been as studied by us in the frame of a wider research project on artifacts made of a peculiar dark grey limestone spotted with white-to-pink fossil corals of the genus Waagenophyllum. Recorded in an old inventory of the Louvre, the piece in question has quite surprisingly remained unpublished until now. The special points of interest to be addressed here are: the uncommon type of stone, which was presumably obtained from some place in Iran; the finely carved lion image that decorates the vessel; and the mysterious iconographic motif that is placed on the lion’s shoulder. A partially preserved Sumerian inscription, most probably to be attributed to the famous ruler Gudea of Lagash should also be noted.1 Close formal and stylistic comparisons with other artifacts of the same period from Tello make it clear that Waagenophyllum limestone, stemming probably from some Iranian source, was imported to Ĝirsu to be locally carved in Sumerian style in the palace workshops. Mesopotamian objects made of this rare stone provide another element for reconstructing the patterns of material exchange between southern Mesopotamia and the Iranian Plateau in the late 3rd millennium Bc.

Symbols at War. The Impact of Corallium rubrum in the Indo-Pakistani Subcontinent

The extraction, trade and ornamental use of corals in the Indo-Pakistani Subcontinent has been traditionally described from the exclusive viewpoint of the Indo-Roman trade, when red Corallium rubrum from the Mediterranean became a crucial export in the system of exchanges described in the famous Periplus Maris Erythraei. The present work focuses on a different version of the story, considering the much longer history of the exploitation and transformation of local Indo-Pacific corals. The historical trajectory presented in this paper examines the apparent rejection of local corals in the early and middle Bronze age and gradual acceptance of local corals in the late Bronze and Iron age. We argue that general replacement of local corals by imported Corallium rubrum in the early historical period is closely associated with the rise of the first Buddhist communities and their rejection of traditional Brahmanic values, in a new world globalised by long-distance trade and the imminent rise of the Kushan imperial political unification.