Research program
Mesozoic rifting events in the Central Mediterranean: paleogeography and tectonic evolution
University Co-ordinator
Università degli Studi di NAPOLI "Federico II" -
SCIENZE DELLA TERRA - NAPOLI(NA)
Research Unit Leader
Alessandro IANNACE
Description
The main task of this U. O. (2) will be a systematic and critical analysis of the Triassic and Jurassic successions aimed to the general understanding of the depositional paleoenvironments and specifically to the quantification, with the highest accuracy, of the subsidence evolution within the different tectono-sedimentary systems.The programmed research activities will develop as follows:1) Bibliography – A significant step of the research will be a systematic, critical evaluation of all the existing literature with the specific objective of collecting all the detailed stratigraphic data and to select the best sedimentary successions, particulary for the areas not directly known to the proponents, upon which to concentrate the next stratigraphic analysis.2) Stratigraphic analysis – The selected sections will be analyzed in terms of facies associations and biostratigraphy. As described below, this work will be partly a deepening of previous study already performed by the proponents, partly an original analysis on sections known from the existing literature. With respect to previous work, a careful attention will be placed on the exact evaluation of the stratigraphic thicknesses in order to minimize the effect of tectonic deformation. Moreover, part of this analytic work will be aimed to the distinction of the syn-rift and post-rift portions of the stratigraphic successions.The proponents have a significant experience on carbonate sedimentology and biostratigraphy. On these topics, scientific collaborations are in progress with other Universities (Erlangen, Heidelberg, Granada). The group include two PhD students who are already actively involved into a stratigraphic and structural analysis of the Calabria successions wihin the frame of another COFIN 2001 project. Moreover, the cooperation with the other U. O. will provide further analytical tools making easier the correlation among the other studied sections.The geographic areas and the stratigraphic intervalto be analyzed will be:- Monti Picentini (Salerno) and Monti di Praia a Mare (Cosenza) for the platform carbonates of Upper Triassic age;- Monti Lattari and Picentini (Salerno) and Monte Pollino (Potenza) for the platform carbonate Jurassic;- Coast Range of Calabria for the Middle Upper Triassic;- Val D'Agri and Lagonegro (Potenza) for the Triassic and Jurassic of the Lagonegro succession.The most important area to study the Upper Triassic platform carbonate is the Monti Picentini group, because they include the only stratigraphic succession where the base of the Norian Dolomia Principale is preserved (Scandone and Sgrosso, 1963). This section, together with another already studied at the Lucania-Calabria border (Parente & Climaco, 1999), will be the reference for the subsidence analysis of similar domain during Upper Triassic. The Picentini Mountains, and specifically the Giffoni-Monti Mai area (Iannace & Zamparelli, 1996), will be also the key sector for the subsidence analysis of the Norian-Liassic intraplatform basins. It is clear; however, that the poor biostratigraphic resolution and the uncertainities on the geochronoloic calibration of the Triassic stages will allow only a broad evaluation of the cumulative subsidence of these successions. Nevertheless, these data will represent a fundamental point when compared on a regional scale with other Triassic and Jurassic examples.A different approach will be followed for the platform carbonates of Jurassic age. In this case, the existence of little deformed calcareous successions and the better stratigraphic resolution will enable a more accurate subsidence study. From the literature and direct experience of the proponents, acquired during CARG gelogical mapping, good stratigraphic sections will be selected for a detailed analysis of the biozones (mainly foraminifers and algae) and of the sedimentary trends to be contrasted with the eustatic curves published for this time slice (Hallam, 2001). This study will be complemented with an isotope stratigraphy study to provide better correlation with the pelagic successions studied by U.O. 1 and 4. Carbon isotope analyses on selected slices of the sections and Sr isotopes analyses on more restricted points should lead to the recognition in the shallow water realm of the well known events of the pelagic realm (Jenkins, 1988; Bartolini et al., 1996; Morettini et al., 2003). Specific theme to be addressed are biological and sedimentological events such as the "facies a Lithiotis" and the Oolitic event of Mid-Jurassic. This comparison with the pelagic record will provide useful constraints also for the understanding of the effect of paleoceanographic and paleoclimatic factors controlling the drowning events. Furthermore, for the subsidence analysis of these succession a cooperation with Heidelberg University researchers, who have recently worked on the basin modelling of Jurassic successions of Morocco (Zuelke et al., 2004) has been established.For the Middle Upper Triassic successions of Northern Calabria, which have an epimetamorphic character, only a rough evaluation of the tectono-sedimentary evolution can be expected, which nevertheless will be useful when compared with similar successions of Tuscany. This will represent the first attempt to substantiate the often proposed correlation between these two sectors (Bigi et al., 1991) and, even considering the approximations imposed by the structural complexity of the Calabria outcrops, will represent an important clue for the main objective of the project. The most significant stratigraphic successions will be carefully revised with special attention to the tectonic structures for a better evaluation of their thickness. In this respect, will be useful the comparison with the Betic Cordillera units, where Anisian to Norian successions with very similar facies evolution have been described (Garcia Tortosa 2002) and which are been already visited by some of the proponents in cooperation with Granada University (Iannace et al., 2004).A significant piece of the study will be the stratigraphic analysis of the Jurassic portion of the Verbicaro succession. This Unit, despite its importance for the understanding of the paleogeography of SouthernApennines, has been studied, after the sixties, only in its Triassic portion (Iannace et al. 1994, Ietto et al., 1995; Climaco et al. 1997). It has been recently demonstrated that it represent the stratigraphic prosecution of the Triassic part of the San Donato Unit (Iannace et al., 2004). Within this project, as part of a PhD on-going thesis, we will analyze the paleoenvironmental and paleotectonic significance of the sharp facies and thickness variations present within the Jurassic and Cretaceous part of the succession (Damiani, 1970) and of the tilted blocks quoted by Climaco et al. (1999).It will be important, in this respect, the collaboration with the U. O. 4 for an estimate of the paleobatimetry of the Jurassic "Calcari con Selce" Formation and some radiolarites quoted by Grandjacquet and Grandjacquet (1962). The latter wil be sampled and studied in detail because they may provide important constraints for paleogeographic reconstructions. The possibility will also be evaluated to study systematically the orientation of cement-filled dykes quoted by Climaco et al. (1997) within the Triassic dolomites of the Verbicaro unit. The exchange with the U. O. 1, which will study better exposed dykes in Sicily, will be fundamental in this case to interpret their orientation in terms of paleotectonic directions of extension.The most sinificant part of the work on the Lagonegro successions will be a very careful re-evaluation of the many, and often contradictory, biostratigraphic data recently published. This will be coupled with field controls and analysis in order to quantify the sedimentary dynamics of this relevant paleogeographic element. A similar approah will be followed for the Budva-Cukali successions of the Dinarides, in this case with the contribute of a foreign component of the project, which has a very wide experience on the Geology of Dinarides.
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