NEOGLOBOQUADRINA ATLANTICA PRAEATLANTICA, NEW SUBSPECIESFROM LATE MIDDLE MIOCENE

A new subspecies of Neogloboquadrina atlantica atlantica previously reported under different names, is here distinguished and named Neogloboquadrina atlantica praeatlantica. Its first occurrence into the Mediterranean dated at 11.78 Ma, is not evolutionary appearance but is related to a global climatic cooling which pushed southwards from high latitude this taxon; however, the area of its evolutionary appearance is not clearly defined; its extinction occurs within the Globigerinoides obliquus extremus Zone. N. atlantica atlantica which evolves from N. atlantica praeatlantica occurs in the Mediterranean at 11.15 Ma, just after the Mediterranean exit of Paragloborotalia siakensis (Le Roy).  &nbsp

HIGH RESOLUTION CALCAREOUS PLANKTON BIOSTRATIGRAPHY OF THE SERRAVALLIAN SUCCESSION OF THE TREMITI ISLANDS (ADRIATIC SEA, ITALY)

The planktonic foraminifer and calcareous nannofossil content of two Middle Miocene sections of the Tremiti Islands (Southern Adriatic Sea) have been studied. The two sections are composed of marly limestones rich in calcareous plankton which show cyclic alternations of indurated (higher carbonate content) whitish and less indurated grey or reddish beds. The two sections represent a succession with a total thickness of 38 m. Samples have been collected at a mean spacing of 10-15 cm; qualitative analyses were performed on one sample per meter but quantitative analyses were made for each sample. The abundance fluctuations of several marker species proved to be a very useful tool to correlate the two sections. The astronomical calibration of the sedimentary cycles provided absolute ages for all the recognised calcareous plankton bioevents.&nbsp

Geomorphological map of the Pianosa Island (Tuscan Archipelago, Italy)

The Island of Pianosa is located in the Tuscan Archipelago, a few kilometers south-east of Elba Island, approximately 40 km from Corsica, and 50 km from the Tuscany coast. It represents the emerged portion of a long N-S submarine ridge connecting the Island of Capraia with Scoglio d'Africa, a very small islet located west of the Island of Montecristo. Pianosa has a sub-triangular shape with a similar to 10 km(2) surface area, a coastal perimeter of approximately 18 km, and a maximum height of 29 m a.s.l. The Pianosa landscape has primarily been formed by coastal and karst processes, which have resulted in numerous related landforms. Due to the particular scientific interest of the island, the Geological Survey of Italy has promoted research on Pianosa Island aimed at the development of a 1:12,500 scale geomorphological map

Neogloboquadrina atlantica praeatlantica, new subspecies from late Middle Miocene

3noreservedA new subspecies of Neogloquadrina atlantica atlantica previously reported under different names, is here distinguished and named Neogloboquadrina atlantica praeatlantica. Its first occurrence into the Mediterranean dated at 11.78 Ma, is not evolutionary appearance but is related to a global climatic cooling which pushed southwards from high latitude this taxon; however, the area of its evolutionary appearance is not clearly defined; its extinction occurs within the Globigerinoides obliquus extremus Zone. N. atlantica atlantica which evolves from N. atlantica praeatlantica occurs in the Mediterranean at 11.15 Ma, just after the Mediterranean exit of Paragloborotalia siakensis (Le Roy).mixedFORESI, L.M.; IACCARINO, S., SALVATORINI, G.Foresi, L. M.; Iaccarino, S.; Salvatorini, G

The Middle Miocene climatic transition in the Southern Ocean: Evidence of paleoclimatic and hydrographic changes at Kerguelen plateau from planktonic foraminifers and stable isotopes

Middle Miocene (14.8–11.9 Ma) deep-sea sediments from ODP Hole 747A (Kerguelen Plateau, southern Indian Ocean) contain abundant, well-preserved and diverse planktonic foraminiferal assemblages. A detailed study of the climatic and hydrographic changes that occurred in this region during the Middle Miocene Climatic Transition led to the identification of an intense cooling phase (the Middle Miocene Shift). Abundance fluctuations of planktonic foraminiferal species with different paleoclimatic affinities, and oxygen and carbon stable isotopes have been integrated in a multi-proxy approach. Reconstruction of changes in foraminiferal faunal composition and diversity through time were the basis for identification of three foraminiferal biofacies. The most prominent faunal change took place at 13.8 Ma, when a fauna with warmwater affinity (marked by high abundance of Globorotalia miozea group and Globoturborotalita woodi plexus) was replaced by an oligotypic, opportunistic fauna with typical polar characters and dominated by neogloboquadrinids. This faunal change is interpreted as the result of foraminiferal migration from adjacent bioprovinces, caused by modifications in climate and hydrography. A positive 2.0‰ shift in δ18O (interpreted as the Mi3 event) and a related positive 1.0‰ shift in δ13C (corresponding to the CM6 event) accompanied this faunal turnover. These are interpreted to reflect substantial reorganization of Southern Ocean waters, the northward migration of the Polar Front and a strong increase in primary productivity. The second faunal change took place at 12.9 Ma and was characterized by the gradual decrease in abundance of the neogloboquadrinids and the recovery of Globorotalia praescitula/scitula group and Globigerinita glutinata. A positive 1.5‰ shift in δ18O (interpreted as the Mi4 event) and a concurrent gradual negative shift in δ13C accompanied this faunal change, witnessing further modifications of the climate/ocean system. Variations in sea surface temperature, considered as the main factor causing changes of surface hydrography at the Kerguelen Plateau, seem to have been driven by obliquity and long-term eccentricity, thus suggesting a key role played by the astronomical forcing on the evolution of Southern Ocean dynamics during the Middle Miocene. Also an evident 1.2 Myr modulation of the δ13C record suggests a main control of the long-term obliquity cycles on the carbon cycle dynamics. Particularly, the Mi3/CM6 events exactly fit with a node of the 1.2 Myr modulation cycles. This confirms the key role played by orbital parameters on high-latitude temperatures and Antarctic ice volume, and indirectly on global carbon burial and/or productivity. This climatic transition was marked also by changes in surface hydrography. From 14.8 to 13.8 Ma an intermediate-strength thermocline controlled by seasonality developed just below the photic zone. Weaker seasonality characterized the interval from 13.8 to 12.9 Ma, when the thermocline became shallower and sharper and favored intermediate-water foraminifers. From 12.9 Ma, seasonality increased again and an intermediate-strength thermocline re-developed

Revisiting the taxonomy of the intermediate stages in the Globigerinoides–Praeorbulina lineage

Despite the biostratigraphic and chronostratigraphic importance of the Globigerinoides trilobus-Praeorbulina evolutionary lineage in the upper Burdigalian to Langhian interval, some uncertainties concern the taxonomic interpretation of the intermediate stages of this lineage, in particular the generic attribution of the species sicanus De Stefani 1952 and its relationship with Globigerinoides bisphericus Todd 1954 and Praeorbulina glomerosa curva (Blow 1956). In this study, we present: 1) a review of the intermediate stages of the Globigerinoides trilobus-Praeorbulina evolutionary lineage focussing on the different taxonomic concepts of the species bisphericus, sicanus and glomerosa curva which according to Blow (1956; 1969) and Jenkins et al. (1981) gave rise to two different lines of evolution, and 2) our concepts based on the study of assemblages from several Mediterranean successions which have been compared with those of mid- and low-latitude Atlantic Ocean. On the basis of several diagnostic characters, we identified three morphotypes (Morphotypes 1, 2 and 3) within the populations transitional from G. trilobus to Praeorbulina. In our assemblages, Morphotype 3 and Morphotype 2 are the most representative ones and are considered as Globigerinoides sicanus sensu Blow (1956; 1969) and Kennett and Srinivasan (1983) and as a variant of G. sicanus, respectively. In fact, the taxonomic concepts of Blow, which take both the population variability and the gradual stratigraphic evolution of the biocharacters into account, can be better applied to our assemblages than those of Jenkins et al. (1981), which are mainly based on the characteristics of the holotypes without considering the variability of the species. Accordingly, the evolution of Praeorbulina via G. sicanus (senior synonym of G. bisphericus) proposed by Blow (1956; 1969) can be followed in the studied assemblages and the Praeorbulina datum is represented by the first appearance of P. glomerosa curva. On the basis of our data the evolution of P. glomerosa curva from G. sicanus lasts more than one myr. The main evolutionary changes within G. sicanus populations leading to Praeorbulina are the appearance of specimens with three apertures and the gradual increase in the outline sphericity. Near-spherical individuals of G. sicanus with three apertures can be considered very close to P. glomerosa curva, which in turn is characterized by a spherical outline, at least four apertures with the primary aperture nearly undistinguishable from the supplementary ones and a close umbilicus. Ultimately, our re-examination of the intermediate stages between G. trilobus and Praeorbulina results in a re-evaluation of the evolution proposed by Blow (1956; 1969) with significant bio- and chronostratigraphic implications

The St. Peter’s Pool section (Malta Island): progress towards the Langhian GSSP

The main goal of the project “In search of the Global Stratotype Section and Point of the Langhian Stage and paleoceanographic implication” granted by the Italian Ministry of University and Research and supported by the Subcommision on Neogene Stratigraphy, was to find a potential candidate for hosting the Langhian GSSP. In the framework of the project several sections were investigated and among the others the St. Peter’s Pool one (Foresi et al., 2011), spectacularly outcropping in the Delimara Peninsula, SE of the Malta Island. This section was studied through high-resolution bio-magnetostratigraphy, which resulted in a remarkable improvement of the Mediterranean Langhian knowledge. Calcareous plankton quantitative analyses allowed the definition of several bioevents with a great potential for biostratigraphic correlations. To the well-known bio-horizons, such as the Helicosphera ampliaperta Last Common Occurrence (LCO), the Sphenolithus heteromorphus Paracme and the Paragloborotalia siakensis Acme, many others were added, such as the Paragloborotalia bella LCO and a new P. siakensis Acme, documented for the first time in the Mediterranean area. The following aspects play in favor of the St. Peter’s Pool section as a candidate for hosting the Langhian GSSP: • the excellent exposure and the easy accessibility; • the well-preserved and abundant content of calcareous plankton and the high number of significant bioevents. Two of these can be selected for approximating the Langhian GSSP, namely the LCOs of the nannofossil H. ampliaperta and of the planktonic foraminifer Paragloborotalia bella, both falling in the Chron C5Cn.1n. Particularly the LCO of H. ampliaperta represents a well-defined horizon, also recognizable in extra Mediterranean areas, and its choice could represents a good compromise between thee two recommended events for the definition of the Langhian GSSP (the Praeorbulina datum and the C5Cn/C5Br reversal); • the stratigraphic continuity with the section yielding the Serravallian GSSP (Ras il-Pellegrin in Malta Island); • the cyclic pattern of the succession. On the other hand the magnetostratigraphic data show some uncertainties. Yet, the cyclostratigraphic reconstruction, which is the subject of ongoing studies, has a high potential for establishing a reliable astronomical tuning of the section, providing a further positive element for proposing it as a candidate for the Langhian GSSP. The study will be completed by Oxygen and Carbon isotopes analyses to individuate global paleoclimatic changes

High resolution calcareous plankton biostratigraphy of the Serravallian succession of the Tremiti Islands (Italy)

The planktonic foraminifer and calcareous nannofossil content of two Middle Miocene sections of the Tremiti Islands (Southern Adriatic Sea) have been studied. The two sections are composed of marly limestones rich in calcareous plankton which show cyclic alternations of indurated (higher carbonate content) whitish and less indurated grey or reddish beds. The two sections represent a succession with a total thickness of 38 m. Samples have been collected at a mean spacing of 10-15 cm; qualitative analyses were performed on one sample per meter but quantitative analyses were made for each sample. The abundance fluctuations of several marker species proved to be a very useful tool to correlate the two sections. The astronomical calibration of the sedimentary cycles provided absolute ages for all the recognised calcareous plankton bioevents

Carta geomorfologica dell’Arcipelago Toscano. Isola di Pianosa

This volume is the final issue of a research project on geomorphological mapping at different scales,carried out in the Tuscan Archipelago within an agreement between ex APAT-Geological Survey of Italy-Department Soil Defense and the Department of Geological Sciences of “Roma Tre”University.The resulting maps,digital data-base and explanatory notes (in this volume) represent, without any doubt,an important event.In fact,it introduces geomorphological information to the environmental knowledge of the archipelago, that has been deeply investigated just from the geological and petrological points of view. After an introductory chapter concerning the archipelago geology and climatology,the volume presents a detailed description of the geomophological features of each island. Exception made for Pianosa and Giannutri, all islands are characterized by a rough topography, essentially resulting from the selective erosion of the bedrock, made of a large variety of rock-types.Erosional landforms are predominant with respect to depositional landforms. Among coastal features,cliffs are frequent and well developed,whereas inactive abrasion platforms are few and sometimes of uncertain interpretation.Old dune deposits are relatively frequent along the coast of the Elba and Pianosa islands. Fluvial-denudational and weathering processes are dominant in the inner sectors; karstic landforms are present in Pianosa and Giannutri. Fluvial-denudational landforms are mostly erosional (fluvial valleys,gullies,rills),whereas depositional landforms (alluvial and coastal plains) are less frequent.The weathering processes originate tors, honeycomb sculptures, tafoni and thick weathering mantles. Gravitational processes include degradational escarpments, rockfalls, slides, and rare flows. Talus is widely developed at the foot of slopes. The islands of the Tuscan Archipelago are inhabited since prehistoric times. In protohistoric and historic times, mining in the Elba and Giglio islands, farming, and pasturing induced strong environmental changes. In the last centuries,new and more intensive man-made landforms (urban areas,penality buildings,hydraulic regulation of streams,portual infrastructures) have increasingly modified the landscape of the Tuscan Archipelago

Carta geomorfologica dell’Arcipelago Toscano. Isola di Montecristo

This volume is the final issue of a research project on geomorphological mapping at different scales,carried out in the Tuscan Archipelago within an agreement between ex APAT-Geological Survey of Italy-Department Soil Defense and the Department of Geological Sciences of “Roma Tre”University.The resulting maps,digital data-base and explanatory notes (in this volume) represent, without any doubt,an important event.In fact,it introduces geomorphological information to the environmental knowledge of the archipelago, that has been deeply investigated just from the geological and petrological points of view. After an introductory chapter concerning the archipelago geology and climatology,the volume presents a detailed description of the geomophological features of each island. Exception made for Pianosa and Giannutri, all islands are characterized by a rough topography, essentially resulting from the selective erosion of the bedrock, made of a large variety of rock-types.Erosional landforms are predominant with respect to depositional landforms. Among coastal features,cliffs are frequent and well developed,whereas inactive abrasion platforms are few and sometimes of uncertain interpretation.Old dune deposits are relatively frequent along the coast of the Elba and Pianosa islands. Fluvial-denudational and weathering processes are dominant in the inner sectors; karstic landforms are present in Pianosa and Giannutri. Fluvial-denudational landforms are mostly erosional (fluvial valleys,gullies,rills),whereas depositional landforms (alluvial and coastal plains) are less frequent.The weathering processes originate tors, honeycomb sculptures, tafoni and thick weathering mantles. Gravitational processes include degradational escarpments, rockfalls, slides, and rare flows. Talus is widely developed at the foot of slopes. The islands of the Tuscan Archipelago are inhabited since prehistoric times. In protohistoric and historic times, mining in the Elba and Giglio islands, farming, and pasturing induced strong environmental changes. In the last centuries,new and more intensive man-made landforms (urban areas,penality buildings,hydraulic regulation of streams,portual infrastructures) have increasingly modified the landscape of the Tuscan Archipelago