Fabrizio Antonioli

Sea-level during the penultimate interglacial period based on a submerged stalagmite from Argentarola Cave (Italy)

Accurate constraints are presented for the absolute age, duration and sea-level for the highstand corresponding to marine isotope stage (MIS) 7.1. Our work is based on a stalagmite collected in a currently submerged cave from Italy (Argentarola Cave). Flooding of this coastal cave is clearly marked within the stalagmite by a thick marine overgrowth of serpulid worms. Precise uranium^thorium (U^Th) ages measured by thermal ionization mass spectrometry suggest that the stalagmite growth varied in phase with climate during MIS 7.2 and MIS 6, the penultimate glacial period. In addition, the period of marine transgression is bracketed between 202 and 190 kyr BP, defining a MIS 7.1 duration of 11 ˛ 2 kyr. Comparison with previous studies provides a new constraint on the sea-level during MIS 7.1 that has approximately remained between 318 and 39 m relative to present sea-level. The timing of the MIS 7.1 highstand is in full agreement with the SPECMAP chronology which contrasts with the growing body of evidence showing a significant phase difference for MIS 5.5. A tempting conclusion is that second order sea-level highstands such as MIS 7.1 may be purely driven by astronomical changes, in contrast with major terminations such as Termination II. Atmospheric CO2 levels may partly explain this contrast since the two sea-level transitions, (MIS 7.2^7.1 and MIS 6^5.5) are characterized by very different CO2 rises (20 vs 100 ppm). fl 2002 Elsevier Science B.V. All rights reserved.

Hydrological conditions over the western Mediterranean basin during the deposition of the cold Sapropel 6 (ca. 175 kyr BP)

A new oxygen isotope record is reported from a stalagmite collected in the Argentarola Cave located on the Tyrrhenian coast of Italy. As shown from observations and numerical modeling of N 18 O in modern precipitation, the recorded N 18 O variability for this zone is dominated by the amount of precipitation (so-called ‘amount effect’). The N 18 O profile measured in the stalagmite is characterized by a prominent negative excursion (ca. 2^3x) between 180 and 170 kyr BP. This paleoclimatic feature is interpreted as being due to a relatively wet period which occurred during the penultimate glacial period, more precisely, during Marine Isotope Stage 6.5. This pluvial phase is shown to correspond chronologically to the deposition of the sapropel event 6 (S6). Although this particular sapropel event occurred during a cold phase, the N 18 O excursion is similar to those corresponding to other sapropels (S4, S3 and S2). The evidence for humid conditions during S6 in the western Mediterranean basin agrees with previous studies based on deep-sea sediment cores. Taken collectively, the data suggest that during sapropel events dilution of ocean surface waters was not restricted to the output of the river Nile but was rather widespread over the entire Mediterranean Sea due to increased rainfall. < 2002 Elsevier Science B.V. All rights reserved.

Phasing and amplitude of sea-level and climate change during the penultimate interglacial

The penultimate interglacial period was punctuated by three sea-level highstands. Uranium–thorium ages obtained from speleothems in Italian caves show that the relationship between the timing of the peaks in sea level and Northern Hemisphere insolation is dependent on the previous extent of continental ice sheets.

Dendropoma lower intertidal reef formations and their palaeoclimatological significance, NW Sicily

Abstract Most carbonate rocky shores of NW Sicily are marked by a coalescence of shells of the gastropod Dendropoma in a construction that is variably developed as a response to wave impact. Here, we review all the available information on these constructions and find that the fossil reefs are reliable sea-level indicators. The thickness of the reef samples never exceeds 30–40 cm below sea-level, whereas all 14 C dates fall within a range of few centuries. Some small fragments ejected by violent sea storms date back to 2500 years cal BP. No samples older than 6200 years cal BP have been detected so far. The present distribution of Mediterranean vermetid platforms should result from a northward migration related to the long term effect of the Holocene sea surface temperature (SST) warming. Some consideration on the morphology of the reefs and the comparison with the available data point out that Dendropoma reefs are excellent biological indicators of sea-level fluctuations especially when detected and sampled in tectonically stable areas as those in NW Sicily.

The Mediterranean coral Cladocora caespitosa: a proxy for past climate fluctuations?

Sclerochronology was applied to recent, Holocene and Pleistocene samples of Cladocora caespitosa. Late Pliocene samples were recrystallised and thus unsuitable for sclerochronology. Quaternary samples showed a clear, alternating banding pattern as in the living coral, confirming a marked seasonality of past climate. The computed mean annual growth rates ranged from 2.1 to 6.9 mm year 1 , with highest growth rates during the warmer phase (isotope stage 5e) of the first climate cycle. It is hypothesised that the largest fossil banks of C. caespitosa grew in a coastal environment with considerable alluvial inputs and warmer temperatures than today. D 2003 Elsevier B.V. All rights reserved.

New data on the Holocenic sea-level rise in NW Sicily (Central Mediterranean Sea)

The emerged and submerged coastal tracts of selected areas in NW Sicily (San Vito Lo Capo Promontory and Marettimo Island in the Egadi Archipelago) have been studied by means of an interdisciplinary approach (geomorphological and neotectonic surveys, palaeontological, depositional and petrographical observations) with the aim to characterize the coastal evolution of the sector over a wide time frame (Late Pleistocene and Holocene) and to recognize the geological indicators of relative sea-level fluctuations. Neotectonic studies performed all along the coastal sector through the check of the present-day height of marine notches and of the inner margin of marine terraces of Eutyrrhenian age allowed to assess the entity of post-Tyrrhenian differential crustal movements in the area. The calculated rates of uplift confirm the relative stability of the area in the last 125 ka and that the relative corrections introduced can be considered negligible in the reconstruction of sea-level rise in the last thousand years. On the base of these considerations, the sea-level rise curve which has been drawn for the Holocene through the radiometric dating (14C and U/Th) of submerged speleothems and Vermetid reefs is assumed to gain a regional significance and to represent a good reference datum for the Central–Southern Mediterranean Sea. In addition, the sea-level rise data are in good agreement with the predicted sea-level curves based on geophysical models previously applied to the same study areas.

Holocene sea-level change in Sicily and its implications for tectonic models: new data from the Taormina area, northeast Sicily

The northeast coast of Sicily shows emergent marine features that have been uplifting during the Holocene along the footwalls of two major regional fault systems, the Malta Escarpment and Messina fault system. Previously, uplift rates were interpreted as up to about 1.8 mm/mm a−1. New dates on shelly remains, collected close to sea-level, from the Taormina area north of Mount Etna, and amended sea-level curves, are used to show that uplift over the past 6000 years has been proceeding at a slower rate of about 1.4 mm a−1. However, over a longer time period, from the Tyrrhenian Oxygen Isotope Stage 5.5 (about 125 ka) to the present day, the uplift rate has been yet slower, at about 1 mm a−1. Northeast Sicily lies in a complex plate boundary region whereas, in contrast, the rest of Sicily appears to have been stable throughout the later Quaternary. Further comparisons show that the French Mediterranean coast [Lambeck, Bard (2000) Earth Planet. Sci. Lett., 175, 202–222] is a region of crustal stability, where movement is dominated by subsidence of the outer portion of the proglacial forebulge of the last glaciation. There the coastline has been progressively submerged during the Holocene, and sea level has never been higher than at present. Northeastern Sicily uplift is therefore more likely controlled by plate processes that mask most of the effects of glacio-hydro-isostatic adjustment.

Coastal structure, sea-level changes and vertical motion of the land in the Mediterranean

Abstract The Mediterranean basin is an important area of the Earth for studying the interplay between geodynamic processes and landscape evolution affected by tectonic, glacio-hydro-isostatic and eustatic factors. We focus on determining vertical deformations and relative sea-level change of the coastal zone utilizing geological, archaeological, historical and instrumental data, and modelling. For deformation determinations on recent decadal to centennial time scales, seismic strain analysis based on about 6000 focal mechanisms, surface deformation analysis based on some 850 continuous GPS stations, and 57 tide gauge records were used. Utilizing data from tectonically stable areas, reference surfaces were established to separate tectonic and climate (eustatic) signals throughout the basin for the last 20 000 years. Predominant Holocene subsidence (west coast of Italy, northern Adriatic sea, most of Greece and Turkey are areas at risk of flooding owing to relative sea-level rise), uplift (local areas in southwestern Italy and southern Greece) or stability (northwestern and central western Mediterranean and Levant area) were determined. Superimposed on the long trends, the coasts are also impacted by sudden extreme events such as recurring large storms and numerous, but unpredictable tsunamis caused by the high seismicity of parts of the basins. Supplementary material: A table of locations and timings of the largest tsunamis in the Mediterranean during the last 5660 years BP is available at http://www.geolsoc.org.uk/SUP18757.

A new marker for sea surface temperature trend during the last centuries in temperate areas: Vermetid reef

The presence of Vermetid reefs in temperate waters, their diffusion in the Mediterranean Sea, and the possibility of performing 14 C ages allowed the use of Vermetids as an indicator of sea level changes. We present new data on sea climate trend fluctuations that could be interpreted as Sea Surface Temperature (SST) variations, recorded on Vermetid (Dendropoma petraeum) reefs, by means of isotopic analysis. The isotopic records show positive values of the d 18 O relative to present-day values in the period between 1600 and 1850 AD; this deviation occurs in association with the climatic cooling event known as Little Ice Age (LIA). Subsequently, we can observe the warming trend that characterized the last century. These preliminary results indicate that Vermetids could be considered a new SST proxy-data for the Mediterranean Sea and, more generally, for temperate areas. D 2003 Elsevier B.V. All rights reserved.

Sea level changes and tectonic mobility: Precise measurements in three coastlines of Italy considered stable during the last 125 ky

Abstract Fast uplift or subsidence rates, related to intense tectonic-seismic activity, affect the Mediterranean coasts, especially in its eastern sector and Calabria, whereas other areas appear relatively stable. Along the southern Italian coast, the most widely distributed and therefore useful reference datum is the paleo sea level related to isotopic substage 5e (125 ky). In the present study, this marker (inner edge of marine terrace or notch) has been safely identified along three sectors of the Italian coast generally considered tectonically stable: eastern Sardinia, southern Latium and northwestern Sicily. In Latium the top of the Eutyrrhenian transgression was found to vary between −5 and +9.8 m a.s.l. along a 100 km long coast. A well carved Eutyrrhenian notch can be followed for ca. 35 km along the coast of Orosei in Sardinia, gradually varying in elevation between 7.7 and 10.5 m a.s.l., thus indicating a regional tilt. In Sicily, the inner edges of the Eutyrrhenian terrace and marine notches are at elevations between 8 and 13.9 m a.s.l. In all these areas the stage 5e marker has shown a significant local mobility demonstrating its utility for detailing either areal or linear tectonic activity during the last 125 ky along the Tyrrhenian Sea coasts.