1,720,987 research outputs found
Stratigraphie séquentielle et analyse de l'espace disponible du Jurassique supérieur et du Crétacé inférieur du Bassin de Paris.
No full textProvenance of Upper Pliocene conglomerates of the Mutignano Formation (Abruzzo, Italy) : implications for unraveling the uplift history of the external zones of Central Apennines
No full textThe Maiella escarpment (Apulia platform, Italy): geology and modelling of an Upper Cretaceous scalloped erosional platform margin
No full textThis report focuses on one of the most debated features of the
Maiella geology, i.e. the «paleoescarpment», a ca. 1000 m high erosional
surface, abruptly separating Cretaceous slope from platform
facies. The attempt has been to address some crucial questions such
as the reconstruction of a morphologic model applicable to the
entire exhumed portion of the Maiella escarpment, and to investigate
the relationships between the paleoescarpment morphology and
mechanisms responsible for the platform margin erosion.
Two-dimensional data, three-dimensional reconstruction and
quantitative simulation, enable a reconciliation between the tectonic
and sedimentary interpretation of the erosional mechanisms of the
Maiella margin. Tectonic mechanisms, associated with the activity
of a fault system and earthquake swarms, trigger sedimentary
processes, such as imposing landslides, producing the erosion of the
Maiella platform margin and its scalloped morphology
Quantitative analysis of Upper Jurassic Ellipsactinia limestones: examples from the Lazio-Abruzzi platform margin (Central Apennines, Italy)
No full textNew geological constraints for the extension of northern Apulia platform margin west of the Maiella Mt. (Central Apennines, Italy).
No full textCarbonate production of ancient debris-dominated reefs: An outcrop-based example from the Upper Jurassic Reef Complex of the central Apennines (Italy)
No full textThis study provides the fi rst quantitative
carbonate production estimate of an ancient
debris reef, represented by the Upper Jurassic
reef complex of the central Apennines.
The components of carbonate production
(Pnet, Psed, and Pgross) have been defi ned
entirely on the basis of outcrop data. The reef
volume (Pnet) was reconstructed based on
the present distribution of the Upper Jurassic
reef complex and its relationship with
coeval successions of platform and slope.
The volume of sediment exported along the
slope (Psed) was obtained through the reconstruction
of the thickness reduction pattern
of the reef-derived sediments, at increasing
distances from the platform margin. Several
variables have been introduced to overcome
the lack of data in some areas.
The estimates obtained indicate that the
Upper Jurassic reef complex produced a total
amount of calcium carbonate equal to 1.7–2.3
times the amount of material retained in the
reef complex. This excess volume of sediment
produced was redistributed along the slopebasin
system, up to a distance of ~55 km
from the platform margin. According to the
indices commonly used for quantifying carbonate
production, the Upper Jurassic reef
shows values that are consistently lower than
other ancient and Holocene reef systems.
The interaction between the sedimentologic
characteristics of the reef structure and the
hydrodynamic processes is ultimately seen as
the main mechanism responsible for the low
growth potential and reduced export of reef
material. The methodology and the procedure
used were designed specifi cally for the
site being studied but could potentially be
adapted for use in other regions where the
data required are diffi cult to access
DIFFERENTIAL COMPACTION AS A CONTROL ON DEPOSITIONAL ARCHITECTURES ACROSS THE NORTHERN MARGIN OF THE APULIA CARBONATE PLATFORM (MAIELLA MT., CENTRAL APENNINES, ITALY)
No full textThe role of differential compaction as a control in the creation of accommodation and on compaction-modified depositional features
and stratal geometries across theMaiella platform margin, has been investigated through a combined analysis of seismic scale outcrops,
porosity evaluation and modeling. Geologic evolution and large exposures make the platform margin of the Maiella an ideal place to
investigate the effects of differential compaction.Ahigh-relief cemented carbonate platform, a deep basin filled with highly compactable
deposits, and a prograding grain-rich succession sealing morphologic differences across the platform margin, represent suitable features
for promoting differential compaction.
Stratal relationships across the platform margin exhibit evidence of differential compaction-induced effects, such as basinward
divergence and thickening of strata, updip pinch-out of wedge-shaped stratal packages, and an anticline hinge. Porosity analysis and
modeling indicate that, through progressive loading,mechanical and chemical processes act in concert to destroymost of the depositional
porosity. Mechanical compaction appears to have played the greatest part in the total budget of compaction. However, chemical
compaction seems to have played a prominent role in the formation of geometrically consistent depositional profiles during progradation.
Due to differential compaction across the platformmargin a compaction hinge formed concomitantlywith the beginning of progradation,
producing a basin-facing monocline characterized by the progressive steepening of basinward stratal dips. The resulting compactioninduced
stratal deformation, together with sea level changes, controls the distribution, and depositional timing of wedge-shaped stratal
packages during late Cretaceous and Paleocene and the distribution of coral–algal reef buildups, during the late Eocene–earlyOligocene.
The development of the compaction hinge usually follows the progressive increase of loading, but a decrease in compaction
dissipationmay be caused by overburdening of compactable deposits. This will cause a delayed compaction-induced subsidence, whose
effects will be produced after deposition, i.e. during loading interruption. This mechanism is thought to have an important role in the
timing of compaction-induced subsidence throughout the end of Cretaceous and the early Tertiary, and it is considered, together with sea
level, as themain controlling process of the occurrence and distribution of downslope sediments, during a long-lasting period of platform
emersion
Earthquake-induced turbidites triggered by sea level oscillations in the Upper Cretaceous and Paleocene of Italy.
No full textEarthquakes are widely recognized as triggers for turbidites,
submarine debris flows and slumps. In tectonically active areas,
surprisingly small changes in stress can trigger seismic events,
implying that past sea level changes may be important in
controlling the timing of seismicity and the occurrence of
turbidites. We apply this idea in an analysis of turbidites from
the upper Cretaceous–Paleocene Scaglia Rossa Formation of the
Umbria-Marches region of Italy. These turbidites are composed
of resedimented foraminiferal tests derived from fluidizing
deep-water (1500 m), pelagic sediments; seismic triggering is
the most likely triggering mechanism given this setting and
composition. The timing of these turbidites (and associated
synsedimentary slumps), constrained by biostratigraphy and
magnetostratigraphy, reveals an unusual, non-random temporal
pattern that appears to correlate well with proposed eustatic
fluctuations. This correlation between turbidites and eustatic
fluctuations leads us to suggest that stress and pore fluid
pressure changes associated with changing sea level may
trigger periods of increased seismicity in the geological past
- …
