RICERCA ITALIANA     

The evolution of Ionian and Atlantic rift systems through the events recorded in the sedimentary sequences.

Università degli Studi di Perugia

Abstract

Previous researches carried out during the COFIN 2000 and COFIN 2002, confirmed the hypothesis that the italian peninsula consists of two different parts: (a) the southern part is related to the early rifting phase and successive opening of the southern branch of Tethys, now called Ionian Tethys (FINETTI, 2003; STAMPFLI et al. 1991; STAMPFLI & BOREL, 2002; CIARAPICA & PASSERI, 1998; 2002); (b) the northern part shows a more complex evolution, being linked, in a first phase, to the northern branch of Tethys Ocean and later, after the filling of this former trough, to the rifting and successive opening of the Liguria-Piedmont Ocean (Alpine Tethys of STAMPFLI & BOREL, 2002), that is the northeastern prolongation of the Atlantic Ocean. According to this view, the Southern and Central Apennines (Lagonegro-Molise Basin and the adjacent platforms) are part of the continental margin of the Ionian Ocean, while the Northern Apennines (Tuscany-Umbria-Marche Basin) and a large part of the Alps are the passive continental margins of the Liguria-Piedmont Ocean (with the exception of some eastern sectors as the Hallstatt-Meliata Basin and the Belluno-Slovenian trough). At now, these two rifting systems appear completely disjointed and unrelated for both age of first phase of rifting (Middle Triassic in the Lagonegro Basin, post-Carnian in the northern apenninic and alpine basins) and trend (SE-NW for Lagonegro-Ionian trough, SW-NE for the Liguria-Piedmont trough). This independence caused >>>

Principal Investigator

Leonsevero PASSERI Università degli Studi di PERUGIA

Research Objectives

Between Permian and Late Jurassic the southwestern branch of the Tethys, known as Ionian Ocean, opened and between Late Triassic and Late Jurassic also the Liguria-Piedmont rifting (linked to the Central Atlantic) occurred. From Permian to Middle Triassic the paleogeographic trends of the Mediterranean area are due only to the evolution of the Tethyan Gulf while, since the Late Triassic, they are controlled by the Tethyan evolution to the east and by the opening of the Atlantic Ocean and of its Liguria-Piedmont (L-P) branch to the west and northwest. The different evolution of the L-P Ocean and of the Ionian Ocean lead to consider the two rifting systems as completely independent each other (CIARAPICA & PASSERI, 2002), although in the SENGOR's hypothesis (1984), the two oceanic branches would connect in a hypothetical triple junction. In this view the Italian peninsula is a complex building linked, in part, to the geodynamics of the Tethyan domain (Southern Apennines) and in part to the Atlantic / L-P domain (Northern Apennines, Western - Central Alps and partially Eastern Alps). On this premise, the compared analysis between the evolution of the different segments of the Alps and Apennines can provide an important contribution to understand the geodynamic evolution of the Mediterranean area during the break-up of Pangea.
Aim of this program is to reach some goals that belong to three different levels.
A) The lower level (basal or fundamental) consists on >>>

First Results

During the first phase the main part of field work will be carried out with lithostratigraphic and sedimentological analyses and with samples collecting.

A) STRATIGRAPHY
A 1) Integrated biozonations for the Triassic, on the base of different fossil groups (ammonoids, conodonts, radiolarians, bivalves, foraminifers, algae, palynomorphs, tetrapode footprints) in Lagonegro and Southern Alps. Collection of data in order to define a carbon isotopic curve for most of the Ladinian - Rhaetian interval in Lagonegro and Southern Alps; the obtained curve will be compared with Upper Triassic isotopic curves from literature, which come from areas located far from the Southern Alps and Lagonegro. Collection of samples for magnetostratigraphy.
A 2) Elaboration of biozonations based on radiolarians in some Jurassic sections of the Lagonegro area.
A 3) Elaboration of biozonations based on calcareous nannoplankton calibrated with zonations based on ammonoids in some Jurassic sections ( Gran Sasso, Monte Bulgheria, La Spezia, Val di Lima).
A 4) Preliminary results on the elaboration of biozonations based on foraminifers and algae calibrated with zonations based on ammonoids in some sections of Apennines and Morocco.
A 5) definition of some associations of tetrapod footprints in Southern Alps and in the mediterranean area.

B) EVENTS
B 1) definition of the main events of resedimentation in the Monte Facito fm and their >>>

Timescale

24 months

National and international background

The R.U. of this program have already demonstrated their ability for cooperating during the earlier Cofin 2000 and 2002.
Every unit is characterized by different specializations that make stimulating and efficient the application to the same geological problem.
The Perugia research unit owns a long tradition of studies on sedimentology and stratigraphy of carbonate complexes, and on paleogeographic restorations documented by studies on modern carbonate environments (Red Sea, Maldives, Caicos) and on Mesozoic and Cenozoic carbonate complexes in Southern Alps and Apennines. The sedimentological studies on fossil deposits were always supported by biostratigraphic analyses on the base of benthic foraminifers, ammonoids, radiolarians. In this project to the Perugia unit skilful researchers coming from other universities are added, to enlarge the potentialities and enrich the competences (on nannoplancon, structural geology, stratigraphy and geological experience).
The Padova research unit owns a consistent experience on the Triassic stratigraphy of the Southern Alps and Lagonegro Basin, and has refined its skills in the topics of ammonoid biostratigraphy, conodont biostratigraphy and of tetrapods ichnology. Such experience extends to the stratigraphy and sedimentology of the study areas.
The Camerino R.U. owns great experience on biostratigraphy, paleontology (benthic foraminifers), paleoecology in Mesozoic carbonate platform and transition zones of >>>