local
project:
The
Neogene basins located in the central-eastern Mediterranean area
recorded several tectono-sedimentary, stratigraphical and palaeoecological
events related to the tectono-eustatic activity and to the climatic
and palaeoeceanographical changes which affected the Mediterranean
area during the building of the peri-Mediterranean chains. One
of the more significative time-interval concerning the palaeogeographic
evolution of the Mediterranean is the Messinian stage. During
it, the different building phases of the peri-Mediterranean chains
(i.e. the contemporaneous formation and eastward migration of
the epi-suture and peri-suture basins) caused continuous and important
palaeogeographic changes in the whole Mediterranean domain. More
in detail, within the Messinian stage, a particular time-interval
not yet completely investigated is the post-evaporitic one. This
time-span, comprised between the deposition of the primary evaporites
linked to the Messinian salinity crisis and the restored,at the
beginning of the Early Pliocene, of “normal” marine
conditions in the whole Mediterranean domain, has been characterized
by deep palaeoceanographic and palaeogeographic changes. As a
consequence, all the sedimentary basins changed from hyperhaline
to hypohaline conditions. Their deposits contain fossil assemblages
that show a Parathetyan affinity, due both to a persistent isolation
of the Mediterranean domain from the Atlantic Ocean and to the
contemporaneous connection between Mediterranean and Parathetys.
Moreover, during this period in central Italy a major orogenetic
event took place, with the accretion of the Apennine chain and
its eastward migration towards the Adriatic foreland.
The main goal of this research program is to detail as much as
possible, using high-resolution stratigraphic analyses, modes
and times in which these changes took place. Stratigraphical analyses
will allow to verify if the recognized events were isochronous
in the whole analysed area and could even point out other events
not yet detected from the studies carried out till now on the
Messinian post-evaporitic deposits.
The program of this Research Unit will focus the study on the
analysis of different basins (whose sedimentary successions include
the Messinian-Zanclean boundary) referable to the Apennine Foreland
Basin System (such as pre-orogenic basins developed in the non-flexured
foreland domain and sin- and late-orogenic basins developed in
foredeep and thrust domains) and to its Tyrrhenian hinterland
zone, in order to depict the late Messinian evolution of the Mediterranean
area. Moreover, a new geological survey will start in the Iraklion
Basin (Crete Island) in order to obtain data to compare the stratigraphical
evolution of eastern and central Mediterranean sectors.
As regards the late Messinian Foreland Basin System, the sections
of Perticara (Montefeltro), Maccarone (Apiro, Marche) and Fonte
dei Pulcini (Taranta Peligna, Maiella) have been chosen for a
detailed study. In the Tyrrhenian hinterland, the onshore Mondragone
1 deep-bore-hole will be revised, thank to ENI-Agip that allows
us to re-study the paleontological contents of the sediment cores.
The paleontological study, together with the interpretation of
some reflection seismic lines will lead to describe the tectono-sedimentary
characteristics of this late Messinian basin related to the evolution
of the Tyrrhenian extensional zone.
All the selected stratigraphic successions will be analysed from
a high-resolution cyclostratigraphic point of view, through the
definition of the cyclic variations of some physical-chemical
parameters such as the CaCO3 content, the magnetic susceptibility,
the clay-mineral content, the natural radioactivity and the frequencies
of the micropaleontological record, which are all driven by the
cyclic variations of the orbital parameters which affect the terrestrial
insolation (precession, obliquity and eccentricity). In particular,
it will be interesting to verify a possible astronomical forced
cyclicity of the clay-minerals content, which, at present, it
has not yet been confirmed.
Besides the cyclostratigraphical data, both the qualitative and
the quantitative analyses of the clay-minerals recovered in the
analysed sediments will provide valuable informations about the
palaeoclimate. In fact, both the qualitative and the quantitative
composition of the clay-minerals inside the sediments are linked
to climate. For example, high percentages of smectites have been
related to changes from wet to dry climate conditions. Particularly,
abrupt variations in the smectites percentages have been recorded
at the Messinian/Zanclean boundary relating them to an equally
abrupt climatic change from wet to dry conditions.
All the programmed analyses represent valuable tools to reach
some goals of the national research project such as: the definition
of a high-resolution stratigraphical frame of the late Messinian
and the palaeoenvironmental characterization, on a regional scale,
of the post-evaporitic Messinian successions (task 1); the high-frequency
climatic control on the cyclical patterns of the post-evaporitic
successions (task 5); the regional characterization of the Mio-Pliocene
boundary (task 8).
The aforementioned proposed sections will be analysed from a biostratigraphical,
palaeoecological and palaeoclimatical point of view, using ostracods,
forams, calcareous nannofossils, pollens and dynocysts. The integrated
analysis based on these data will provide a more complete picture
of the major palaeoenvironmental and palaeoclimatical changes
that affected the central-eastern Mediterranean during the Messinian
post-evaporitic time-interval. This analysis will contribute to
the reconstruction of the time-space changes of the Mediterranean
palaeoenvironments and to a better understanding of the complex
relationships between climate, tectonics and eustasy during the
post-evaporitic Messinian. Thus, the integrated study of the proposed
sections will contribute to a better understanding of the environmental
scenarios that developed between the end of the evaporitic deposition
and the Pliocene transgression. In particular, it will help to
verify: 1) the possibilities of superficial waters exchanges between
Mediterranean and Parathetys; 2) the possible sea-water inflows
inside the widespread lago-mare environment that characterised
the Mediterranean after the salinity crisis; 3) the influence
of climatic changes on the Mediterranean hydrologic balance, which
could be at the basis of the main salinity variations recorded
by the Mediterranean waterbody. Therefore, this integrated analysis
could contribute to reach the goals of the following tasks:
Task 1 - palaeoenvironmental characterization, on a regional scale,
of the post-evaporitic Messinian successions;
Task 4 - times and modes of the transition between hyperhaline
to hypohaline conditions;
Task 6 - time and space definition of sea-water inflows on the
Lago-Mare basins and their palaeogeographical implications;
Task 8 - regional characterization of the Mio-Pliocene boundary.
Moreover, through the calibration of the main ecobiostratigraphical
recognized events, the integrated analysis will contribute to
correlate the different examined successions, in order to depict
differences in the physical stratigraphy of the analysed sedimentary
basins. The differences in the tectono-sedimentary evolution could
be eventually related to different geodynamic conditions in the
central-eastern Mediterranean, during the post-evaporitic phase
of the Messinian stage. If the case, a specific contribution will
be provided to those tasks which intend to define the origin of
the intra-Messinian erosive surface (task 3) and the role played
by the Tortonian-Messinian orogenic phase in the origin of the
Messinian events of the Mediterranean area (task 2).
The sedimentological and stratigraphical analyses, which will
be performed by this Research Unit, will benefit of the competences
that are present within the Research Units 5 and 6. Moreover,
the Research Units 3 and 4 will contribute to construct a common
biostratigraphical framework for calcareous nannofossils and forams.
In conclusion, this Research Unit, using ecostratigraphical analyses
(ostracods, forams, calcareous nannofossils, pollens and dynocysts),
cyclostratigraphical analyses (CaCO3 content, magnetic susceptibility,
clay-minerals, natural radioactivity), palaeoclimate analyses
(pollens, dynocysts, clay-minerals), palaeoecological analyses
(ostracods, forams, calcareous nannofossils) and sequence stratigraphy,
will contribute to reach the goals of the following tasks:
Task 1 - definition of a high-resolution stratigraphic frame of
the late Messinian time-interval and palaeoenvironmental characterization
of the post-evaporitic Messinian successions on a regional scale;
Task 2 - definition of the role played by the Tortonian-Messinian
orogenic phases of the Mediterranean area in the origin of the
Messinian events;
Task 3 - definition of the origin of the wide intra-Messinian
erosive surface and of the related deposits;
Task 4 - definition of times and modes of the changes from hyperhaline
to hypohaline conditions of the Mediterranean waterbody;
Task 5 - definition of the role of the high-frequency climatic
control on the cyclical patterns of the post-evaporitic successions;
Task 6 - time and space definition of sea-water influxes on the
Lago-Mare basins and their palaeogeographical implications;
Task 8 - regional characterization of the Mio-Pliocene boundary.
During the first phase of the research, the Research Unit will
complete the sampling of the selected stratigraphical successions.
In particular, the Maccarone section, representing one of the
more complete Messinian post-evaporitic successions, could be
assumed as a type section for this time-interval. This section
will be sampled in detail to provide ostracod, forams, calcareous
nannoplancton, clay-minerals, natural radioactivity, CaCO3 content
and magnetic susceptibility analyses, which will flank the pollen
analyses that have been already performed.
Moreover, it will be implemented the sampling of the Perticara
(Montefeltro) section. At present a detailed sampling has been
performed only in the upper 20 m of the sedimentary succession,
including the upper portion of the Argille a Colombacci Fm. and
the Pliocene Argille Azzurre Fm., and it will be extended to the
lower portion of the Argille a Colombacci Fm. Regarding Fonte
dei Pulcini section (Maiella), the sampling has already been carried
out on the upper 70 m of the Messinian post-evaporitic deposits
and on the basal 230 m of Lower Pliocene clays, but it will be
extended, as far as it will be possible, towards the Messinian
evaporites. A new sequence stratigraphic survey will start in
the Neogene Iraklion basin (Crete Island) in order to define the
tectono-sedimentary conditions that was established near the Mio-Pliocene
boundary and to compare them with the results of the studies carried
out on the central Mediterranean areas. Moreover, in the first
phase of the research, the samples will be prepared for laboratory
analyses (micropaleontological, geochemical, mineralogical and
palaeomagnetical analyses). Then, the analyses will be performed
using the appropriate instruments: stereomicroscopes and SEM for
the micropaleontological analyses, X-ray diffractometer for the
qualitative and quantitative analyses of the clay-minerals, geochemical
analyses for the CaCO3 content and palaeomagnetical analyses for
magnetic susceptibility.
During the second research phase, the results of the previously
listed analyses will be elaborated and integrated. The quantitative
analyses which will be performed on the Maccarone type-section
will be used to compare, identify and correlate the cyclicity
detected in the other sections, in order to: 1) calibrate the
main tectono-sedimentary, ecobiostratigraphical and palaeoclimatical
events recognized in the examined sections; 2) understand the
palaeoenvironmental scenarios verified during the Messinian post-evaporitic
phase in the central-eastern Mediterranean; 3) define times and
modes in which the main palaeoenvironmental changes was settled;
4) compare the recognized events recorded in the different tectono-sedimentary
environments in the central Mediterranean to those which affected
the Crete Island.
Finally, the obtained results will be put, together with those
accomplished by the other Research Units (in particular Units
4, 5, 6 and 7) in a regional GIS data-base which will be used
to define two or more tectono-sedimentary transects through the
Tyrrhenian-Apennine system. These transects could evidence possible
differences in the times and ways in which the different central
Mediterranean sedimentary basins developed during the late Messinian
Lago-Mare event.
Notes to the economic plan of the project
As a justification of the estimated cost for “Materiale di
consumo e funzionamento”), it is worth to note the high number
of laboratory analyses planned in the project. As a consequence,
taking into account both the sample number that have to be treated
(>400) for each different analytical techniques (ostracods,
forams, nannofossils, pollen, geochemistry, XRD clay minerals)
and the expensive cost of the sample treatment for pollen analysis
(15€/sample), about the 80% of the total amount will be utilized
to purchase consumables for sample treatment laboratories.
