Michele Morsilli

Jurassic Dinosaur Footprints from Southern Italy: Footprints as Indicators of Constraints in Paleogeographic Interpretation

Abstract Three loose blocks, rich in dinosaur footprints, were found in a small pier at Mattinata (Gargano Promontory, Foggia, Italy), most probably quarried from the Upper Jurassic Sannicandro Formation. All of the footprints in the blocks are ascribed to medium-sized theropod trackmakers. Recent track discoveries from both the Early Cretaceous San Giovanni Rotondo Limestone and the Late Cretaceous Altamura Limestone, as well as this new discovery, reveal the consistency of terrestrial associations along the southern margin of the Tethys Ocean in the peri-Mediterranean area at the end of Jurassic through Cretaceous times. The presence of these dinosaur-track-rich levels within marine sediments of the Apulia Platform underlines the relevance of dinosaur footprints as a means of constraining paleogeographic reconstructions.

CARBONATE FACIES ZONATION OF THE UPPER JURASSIC-LOWER CRETACEOUS APULIA PLATFORM MARGIN (GARGANO PROMONTORY, SOUTHERN ITALY)

The Late Jurassic-Early Cretaceous Apulia platform margin and the transition to adjacent basinal deposits (inner platform to basin) are well exposed in the Gargano Promontory. Detailed field work has allowed to recognize eight main facies associations which reflect various depositional environments, and which document a differentiated zonation, from the inner platform to the basin. A shallow lagoon existed in the internal part of the Gargano Promontory with a transition to tidal flat areas (F1). Oolitic shoals (F2) bordered this internal peritidal area passing seaward to a reef-flat with abundant corals (F3). A reef-front, associated with a coral rubble zone, has been found in some areas (F4). In the external margin zone, massive wackestones with Ellipsactinia occur (F5) and pass gradually to a rudstone facies on the proximal slope (F6). The base-of-slope facies association consists of pelagic sediments interbedded with gravity-displaced deposits (F7 and F8). The depositional profile of the Apulia Platform is typical of the Tethyan Jurassic-Early Cretaceous platforms, with slope declivities in the order of 25°-28°. The remarkable progradation of the platform in the northern tract of the Gargano (Lesina and Varano lakes area) and its substantial stability east- and southwards (Mattinata area) suggest a possible windward position of the margin in this latter portion and, in contrast, a leeward position of the northern portion.

Rhodolith-rich lithofacies of the Porto Badisco Calcarenites(upper Chattian, Salento, southern Italy)

This study describes the rhodolith-rich lithofacies of the Porto Badisco Calcarenites, an upper Chattian rhodalgal/larger foraminiferaldominated unit exposed in the southern part of the Apulia Carbonate Platform (Salento Peninsula, Italy). The lensoid rhodolith-rich lithosome at the base of the studied section is made of rhodolith rudstone and floatstone which infill a channel-like depression inherited from the substrate. Changes in the texture of the rhodolith facies and in the inner structure of the rhodoliths reflect variations in submarine current velocity across the section of the channel. Inherited topography controlled both the locus and the mode of rhodolith accumulation. The rhodolith lithosome is bounded by a flat surface above which rhodoliths are notably absent and beds are tabular. This implies that rhodolith accumulation ended as soon as substrate topography was completely levelled off. The taxonomic composition of the red algal and larger foraminiferal assemblages suggests that the rhodolith-rich unit deposited in the oligophotic zone. The abundance of tropical genera among the coralline algae (Lithoporella and Sporolithon) and the high diversity of larger foraminiferal assemblages indicate that the deposition of the Porto Badisco Calcarenites took place in the warm waters of the tropical to subtropical zone

DROWNED KARST LANDSCAPE OFFSHORE THE APULIAN MARGIN (SOUTHERN ADRIATIC SEA, ITALY)

The south Adriatic shelf offshore of the predominently carbonate Apulian coast is characterized by a peculiar rough topography interpreted as relic karst formed at a time of lower sea level. The study area covers a surface of about 220 km, with depths ranging from 50 to 105 m. The most relevant and diagnostic features are circular depressions a few tens to 150 m in diameter and 0.50 to 20 m deep thought to be dolines at various stages of evolution. The major doline, Oyster Pit, has its top at about 50 m water depth and is 20 m deep. It is partly filled with sediments redeposited by episodic mass failure from the doline’s flank. Bedrock samples from the study area document that Plio-Pleistocene calcarenites, tentatively correlated with the Calcarenite di Gravina Fm, are a prime candidate for the carbonate rocks involved in the karstification, although the presence of other units, such as the Peschici or Maiolica Fms, is not excluded. The area containing this subaerial karst landscape was submerged about 12,500 years ago as a result of the postglacial transgression over the continental shelf.

Quantifying the geometry and sediment fabric of linear slopes: examples from the Tertiary of Italy (Southern Alps and Gargano Promontory)

The geometries and sediment characteristics of two well-exposed submarine slope successions of ancient carbonate platforms were studied to analyse the relationship between inclinations of linear slopes and sediment fabric. The two examples are an Oligocene platform-to-slope succession exposed on the Brione Mountain in the Southern Alps, and an Eocene slope-tobasin succession exposed on the Saraceno Mountain in the Gargano Promontory. The planar slope of the Brione Mountain outcrop is inclined up to 20–25j and consists of fine to coarse sand sized, skeletal packstones and grainstones, and that of the Saraceno Mountain outcrop has a modal angle of 15–22.5j, and comprises very fine to coarse sand sized, poorly washed skeletal packstones, grainstones, and rudstones. The good agreement between the inclinations of the linear slope profiles and angles of repose published in the literature implies that these slopes are at or very close to the angle of repose. The general rule that in systems built to the angle of repose, slope angle is directly correlated to sediment fabric, can be applied to linear slopes. D 2002 Elsevier Science B.V. All rights reserved.

The Apulia Carbonate Platform—Gargano Promontory, Italy (Upper Jurassic–Eocene)

The Upper Jurassic to Eocene carbonate rocks of the Gargano Promontory belong to the Apulia Carbonate Platform (ACP) and provide a spectacular and complete succession of slope and base-of-slope resedimented gravity flow carbonates with preserved reservoir properties and, with its coeval carbonate platform, displaying various tectonostratigraphic architectures. The ACP margin is characterized by an overall aggrading architecture, and different geometric and depositional features. Facies types and sedimentary dynamics of the carbonate slope and gravity deposits can be analyzed with respect to the stratigraphic architecture of the platform-to-basin transition. These outcrops are the only analogs of some important oil reservoirs and plays present in the equivalent slope to basin succession in the Adriatic offshore and elsewhere.

FISH FEEDING TRACES FROM MIDDLE EOCENE LIMESTONES (GARGANO PROMONTORY, APULIA, SOUTHERN ITALY)

ABSTRACT More than two hundred subcircular to crescent-shaped depressions, often with radiating markings, were discovered on a 120 m2 bedding plane interpreted as base-of-slope carbonate deposits and belonging to the Lutetian–Bartonian Peschici Formation at San Lorenzo (Vieste, Gargano Promontory, Italy). The area was mapped using a high-resolution aerial camera (mounted on a kite) and a terrestrial laser scanner. The survey allowed detailed morphologic analysis and topographic mapping of the traces, in order to analyze the very regular distribution pattern. The ichnological study, combined with sedimentologic and stratigraphic analyses, identifies the depressions as fish feeding traces. Although the tracemaker cannot be definitely identified, the comparison with modern and fossil fish excavations suggests a higher affinity with bony fishes (e.g., sturgeons) than with rays. The trace fossils are here attributed to the ichnogenus Piscichnus and constitute the first discovery of this ichnotaxon in the middle Eocene of the Apulia Carbonate Platform and of Italy.

A THEROPOD DOMINATED ICHNOCOENOSIS FROM LATE HAUTERIVIAN-EARLYBARREMIAN OF BORGO CELANO (GARGANO PROMONTORY, APULIA, SOUTHERN ITALY)

Several dinosaur footprints were discovered on three different levels cropping out in the CO.L.MAR quarry, south of the village of Borgo Celano in the Gargano Promontory (Apulia, southern Italy). The track-bearing levels belong to a carbonate inner platform succession referred to the Lower Cretaceous (upper Hauterivian-lower Barremian). This paper describes only the lowest dinoturbated bed, where footprints are preserved as natural cast. Forty footprints, mostly tridactyl, have been attributed to medium-sized theropods. Tridactyl tracks are similar to Kayentapus Welles, 1971 regarding ichnotaxonomy. Round shaped footprints, previously not described from this site, are found in association with tridactyl footprints and are related to ornitischian dinosaurs.

ABSTRACT: Carbonate Production, Relative Sea Level Fluctuations and Slope Geometry: Case Histories from the Middle-Triassic of the Italian Dolomites

The understanding of carbonate platform reservoirs can be enhanced through the analysis of outcropping counterparts, such as the ones provided by the study platforms (Cernera and Latemar), particularly rich in both marine cements and microbial boundstones. The birth of both coeval platforms was matched with an anoxic event and with the deposition of a potential source horizon, rich in marine organic matter. The evolution of the short lived Cernera Platform was controlled by a very fast subsidence, badly compensated by its aggrading evolution. The lengthening slopes rapidly steeped up, while the cementation intensity increased. The carbonate production was unable to support the fast platform volume increase and the slope deposits therefore became thinner and thinner, forcing the margin to retrograde; the platform eventually drowned and it was covered by condensed pelagic facies and deep water stromatolite-like structures. The Latemar slope experienced a similar lengthening and steeping up evolution; this carbonate system however grew in a comparatively less subsiding area and it was therefore able to keep and eventually catch up the relative sea level increase. While the platform core shallowed from subtidal environments to cyclic emersions, in the adjacent slopes loose bioclastic and micritic sediments gave place to breccia rich in carbonate cements and microbial boundstones. The subsidence then slowed down considerably enabling the platform to laterally prograde, but no margin are presently preserved from this phase. Both platforms were then at least partially sealed by volcanic and terrigenous deposits and incompletely affected by a permeability enhancing dolomitization.