Subduction, convergence and the mode of backarc extension in the Mediterranean region

Abstract 30-35 Ma ago a major change occurred in the Mediterranean region, from a regionally compressional subduction coeval with the formation of Alpine mountain belts, to extensional subduction and backarc rifting. Backarc extension was accompanied by gravitational spreading of the mountain belts formed before this Oligocene revolution. Syn-rift basins formed during this process above detachments and low-angle normal faults. Parameters that control the formation and the kinematics of such flat-lying detachments are still poorly understood. From the Aegean Sea to the Tyrrhenian Sea and the Alboran Sea, we have analysed onshore the deformation and P-T-t evolution of the ductile crust exhumed by extension, and the transition from ductile to brittle conditions as well as the relations between deep deformation and basin formation. We show that the sense of shear along crustal-scale detachments is toward the trench when subduction proceeds with little or no convergence (northern Tyrrhenian and Alboran after 20 Ma) and away from the trench in the case of true convergence (Aegean). We tentatively propose a scheme explaining how interactions between the subducting slab and the mantle control the basal shear below the upper plate and the geometry and distribution of detachments and associated sedimentary basins. We propose that ablative subduction below the Aegean is responsible for the observed kinematics on detachments (i.e. away from the trench). The example of the Betic Cordillera and the Rif orogen, where the directions of stretching were different in the lower and the upper crust and changed through time, is also discussed following this hypothesis.

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Lateral variations of pressure-temperature evolution in non-cylindrical orogens and 3-D subduction dynamics: the Betic-Rif Cordillera example

10.5194/egusphere-egu21-7837 ◽

2021 ◽

Author(s):

Eloïse Bessière ◽

Laurent Jolivet ◽

Romain Augier ◽

Stéphane Scaillet ◽

Jacques Précigout ◽

...

Keyword(s):

Mediterranean Region ◽

Major Change ◽

Geodynamic Setting ◽

Time Deformation ◽

Complex Interactions ◽

Longitudinal Variations ◽

The Mediterranean ◽

Slab Tearing ◽

Mantle Exhumation

Orogens closely linked to 3-D subduction dynamics are frequently non-cylindrical and the Mediterranean region is a perfect natural laboratory to observe several of them, as well as their interactions. Through the succession of extension, subduction and sometimes collision events, the kinematic reconstructions of such orogens can be difficult and the subject of active debates. The internal zones are often non-consensual, especially when their long-term Pressure-Temperature-time-deformation (P-T-t-d) evolutions are studied. This complexity is mostly due to pre-orogenic inheritance or complex interactions between the subducting lithosphere, the overriding plate and the asthenosphere. All these elements are described and documented in Mediterranean orogens, i.e., a complex shape of the Eurasian and African margins in pre-orogenic times and a complex slab retreat and tearing dynamics. Their 3-D geometry results in strongly arcuate belts, such as the Betic-Rif Cordillera, located in the westernmost part of the Mediterranean region.Focused on the Internal Zones of the Betic-Rif Cordillera and based on recent findings (Orogen Project framework), a synthesis of the tectono-metamorphic evolution shows the relations in space and time between tectonic and P-T evolutions. The reinterpretation of the contact between peridotite massifs and Mesozoic sediments as an extensional detachment leads to a discussion of the geodynamic setting and timing of mantle exhumation. Based on new 40Ar/39Ar ages in the Alpuj&#225;rride Complex (metamorphic formations of the Betic Internal Zones) and a discussion of published ages in the Nevado-Filabride Complex (metamorphic formations of the Betic Internal Zones), we conclude that the age of the HP-LT metamorphism is Eocene in all the Internal Zones. A first-order observation is the contrast between the well-preserved Eocene HP-LT blueschists-facies rocks of the Eastern Alpuj&#225;rride-Sebtide Complex and the younger HT-LP conditions reaching partial melting recorded in the Western Alpuj&#225;rride. We propose a model where the large longitudinal variations in the P-T evolution are mainly due to (i) differences in the timing of subduction and exhumation, (ii) the nature of the subducting lithosphere and (iii) a major change in subduction dynamics at ~20 Ma associated with a slab-tearing event.

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New records of amphipod crustaceans along the Israeli Mediterranean coast, including a rare Mediterranean endemic species, Maera schieckei Karaman & Ruffo, 1971

Biodiversity Data Journal ◽

10.3897/bdj.8.e53864 ◽

2020 ◽

Vol 8 ◽

Author(s):

Sabrina Lo Brutto ◽

Davide Iaciofano

Keyword(s):

Mediterranean Sea ◽

Mediterranean Basin ◽

Eastern Mediterranean ◽

Aegean Sea ◽

Western Mediterranean ◽

Mediterranean Coast ◽

Tyrrhenian Sea ◽

Western Mediterranean Basin ◽

The Mediterranean ◽

Distribution And Ecology

A survey has been carried out at four Israeli rocky sites to evaluate the diversity of the amphipod fauna on various hard substrates, still scarcely monitored, as potential pabulum for amphipod crustacean species. A survey of shallow rocky reefs along the Mediterranean coast of Israel recovered 28 species and integrated the Amphipoda checklist for the country ofIsrael with 12 newly-recorded species. Such renewed national list includes Maera schieckei Karaman & Ruffo, 1971, a rare species endemic to the Mediterranean Sea, recorded here for the first time from the southern Levant Basin. The species, described from specimens collected in the Tyrrhenian Sea in 1970, has been only recorded eight times within the whole Mediterranean Sea. A revision of the bibliography on the distribution and ecology of M. schieckei showed that, although mentioned only for the western Mediterranean basin by some authors, it is listed in the checklist of amphipods of the Aegean Sea and neighbouring seas and has been found in the eastern Mediterranean basin since 1978. Maera schieckei was rarely found in the Mediterranean, one of the most studied marine biogeographic region as concerns the amphipod fauna; and the species seems to prefer bays or gulf areas. The role of updating and monitoring faunal composition should be re-evaluated.

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Late evolution of the inner Northern Apennines from the structure of the Monti del Chianti-Monte Cetona Ridge (Tuscany, Italy)

10.5194/egusphere-egu21-1764 ◽

2021 ◽

Author(s):

Andrea Brogi

Keyword(s):

Middle Miocene ◽

Sedimentary Basins ◽

Northern Apennines ◽

Normal Faults ◽

Tyrrhenian Sea ◽

Scientific Debate ◽

Marine Deposits ◽

Accommodation Space ◽

Tectonic Events ◽

Late Evolution

The Neogene and Quaternary tectonic evolution of the inner Northern Apennines (i.e southern Tuscany and northern Tyrrhenian Sea), as well as its crustal features (i.e. low crustal thickness, Neogene-Quaternary magmatism, widespread geothermal anomalies, lateral segmentation of the stacked tectonic units, extensive deep sedimentary basins), are framed in different geodynamic scenarios: compressional, extensional or both, pulsing. Consequently, the basin and range structure that characterises the northern Tyrrhenian Sea and southern Tuscany is considered as a consequence of (i) out-of-sequence thrusts and related thrust-top-basins, (ii) polyphased normal faulting that formed horst and graben structures or (iii) a combination of both. This paper provides a new dataset from a sector of the eastern inner Northern Apennines (i.e. Monti del Chianti - Monte Cetona ridge) contributing to this scientific debate. New fieldwork and structural analysis carried out in selected areas along the ridge allowed to define the chronology of the main tectonic events on the basis of their influence on the marine and continental sedimentation. The dataset supports for early Miocene - (?) Serravallian in-sequence and out-of-sequence thrusting. Thrusting produced complex staking patterns of Tuscan and Ligurian Units. Extensional detachments developed since later middle Miocene and controlled the Neogene sedimentation in bowl-shaped structural depressions, later dissected by normal faults enhancing the accommodation space for Pliocene marine deposits in broad NNW-trending basins (Siena-Radicofani and Valdichiana Basins). In this perspective, no data supports for active, continuous or pulsing, compressional tectonics after late Serravalian. As a result, in the whole inland inner Northern Apennines the extensional tectonics was continuously active at least since middle Miocene and controlled the basins development, magmatism and structure of the crust and lithosphere.

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Performance evaluation of ECMWF ERA5 Reanalysis waves in the Mediterranean Sea

10.5194/egusphere-egu21-1798 ◽

2021 ◽

Author(s):

Tahsin Görmüş ◽

Berna Ayat ◽

Burak Aydoğan

Keyword(s):

Mediterranean Sea ◽

Correlation Coefficients ◽

Aegean Sea ◽

Predictive Performance ◽

Wave Climate ◽

Northwestern Part ◽

Tyrrhenian Sea ◽

Time Intervals ◽

The Mediterranean ◽

Marine Environment Monitoring

This study evaluates the performance significant wave height hindcast from ECMWF&#8217;s latest atmospheric dataset ERA5 in the Mediterranean Sea. Towards this aim, in-situ products from Copernicus Marine Environment Monitoring Service are used. There are nearly 160 observation points along the Mediterranean Sea which are acquired by different institutions with fixed buoys, moorings, and fixed points. The time intervals dating back to 1980s to nowadays, with most of them belongs to the 2000s. To evaluate the verification of ERA5 wave climate with the actual observations, standard statistical metrics such as correlation coefficients (r) are used to compare two datasets in the selected points. The analysis of two time series is done for overlapping time intervals and also for values above a certain threshold, with the purpose of measuring ERA5&#8217;s predictive performance of storm conditions. Preliminary results showed that the observations and numerical results of ERA5 are relatively well-matched. The average correlation coefficient is r=0.8 for the selected points which are spatially disperse in the basin. In the Aegean Sea, the coefficient is calculated as r=0.83 between the observations and ERA5, from a moored surface buoy near the Mykonos island with the time coverage of between 2001 and 2019. Some other examples can be given from the Adriatic Sea (r=0.90, 2013-2014), Tyrrhenian Sea (r= 0.96, 2013-2015), Northwestern part of the basin (r=0.71, 2007-2019), and Balearic Sea (r=0.81, 2004-2019).

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Terrestrial climate variability and seasonality changes in the Mediterranean region between 15 000 and 4000 years BP deduced from marine pollen records

Climate of the Past ◽

10.5194/cp-5-615-2009 ◽

2009 ◽

Vol 5 (4) ◽

pp. 615-632 ◽

Cited By ~ 102

Author(s):

I. Dormoy ◽

O. Peyron ◽

N. Combourieu Nebout ◽

S. Goring ◽

U. Kotthoff ◽

...

Keyword(s):

North Atlantic ◽

Mediterranean Region ◽

Aegean Sea ◽

Comparative Approach ◽

Climate Signal ◽

The North ◽

Climate Reconstructions ◽

Mediterranean Regions ◽

The North Atlantic ◽

The Mediterranean

Abstract. Pollen-based climate reconstructions were performed on two high-resolution pollen marines cores from the Alboran and Aegean Seas in order to unravel the climatic variability in the coastal settings of the Mediterranean region between 15 000 and 4000 years BP (the Lateglacial, and early to mid-Holocene). The quantitative climate reconstructions for the Alboran and Aegean Sea records focus mainly on the reconstruction of the seasonality changes (temperatures and precipitation), a crucial parameter in the Mediterranean region. This study is based on a multi-method approach comprising 3 methods: the Modern Analogues Technique (MAT), the recent Non-Metric Multidimensional Scaling/Generalized Additive Model method (NMDS/GAM) and Partial Least Squares regression (PLS). The climate signal inferred from this comparative approach confirms that cold and dry conditions prevailed in the Mediterranean region during the Oldest and Younger Dryas periods, while temperate conditions prevailed during the Bølling/Allerød and the Holocene. Our records suggest a West/East gradient of decreasing precipitation across the Mediterranean region during the cooler Late-glacial and early Holocene periods, similar to present-day conditions. Winter precipitation was highest during warm intervals and lowest during cooling phases. Several short-lived cool intervals (i.e. Older Dryas, another oscillation after this one (GI-1c2), Gerzensee/Preboreal Oscillations, 8.2 ka event, Bond events) connected to the North Atlantic climate system are documented in the Alboran and Aegean Sea records indicating that the climate oscillations associated with the successive steps of the deglaciation in the North Atlantic area occurred in both the western and eastern Mediterranean regions. This observation confirms the presence of strong climatic linkages between the North Atlantic and Mediterranean regions.

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On the presence of the Mediterranean endemic Microdeutopus sporadhi Myers, 1969 (Crustacea: Amphipoda: Aoridae) in the Gulf of Naples (Italy) with a review on its distribution and ecology

Mediterranean Marine Science ◽

10.12681/mms.650 ◽

2013 ◽

Vol 14 (3) ◽

pp. 56 ◽

Cited By ~ 2

Author(s):

M. B. SCIPIONE

Keyword(s):

Mediterranean Sea ◽

Aegean Sea ◽

Tyrrhenian Sea ◽

Northern Adriatic Sea ◽

Northern Adriatic ◽

Gulf Of Naples ◽

The Mediterranean ◽

Distribution And Ecology ◽

Island Of Ischia

The species Microdeutopus sporadhi (Crustacea: Amphipoda: Aoridae), endemic of the Mediterranean Sea, was described by Myers in 1969 on material collected from the Aegean Sea in a sheltered environment with high sedimentation rates. A check on the distribution and ecology of M. sporadhi showed that: — although not mentioned in the checklist of amphipods of the Italian seas, it was already found in the central Tyrrhenian Sea in 1983-84 and in the northern Adriatic Sea in 2002-03; — it was rarely found in the Mediterranean Sea, one of the most studied basins as concerns amphipod fauna; but notwithstanding the few records available, the wide ecological spectrum of this species was pointed out. The present study, conducted off the Island of Ischia (Gulf of Naples, Italy), showed the presence of rich and well established populations through time, but only in a peculiar substratum (artificial collectors) and environment (low pH values). The species seems to be able to withstand harsh environmental conditions and probably to conceal itself through a cryptic behaviour, escaping traditional sampling methods. The role of rare or hidden species in bio-assessment should be re-evaluated.

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Terrestrial climate variability and seasonality changes in the Mediterranean region between 15000 and 4000 years BP deduced from marine pollen records

Climate of the Past Discussions ◽

10.5194/cpd-5-735-2009 ◽

2009 ◽

Vol 5 (1) ◽

pp. 735-770 ◽

Cited By ~ 5

Author(s):

I. Dormoy ◽

O. Peyron ◽

N. Combourieu-Neboutb ◽

S. Goring ◽

U. Kotthoff ◽

...

Keyword(s):

North Atlantic ◽

Mediterranean Region ◽

Aegean Sea ◽

Comparative Approach ◽

Climate Signal ◽

The North ◽

Climate Reconstructions ◽

Mediterranean Regions ◽

The North Atlantic ◽

The Mediterranean

Abstract. Pollen-based climate reconstructions were performed on two high-resolution pollen – marines cores from the Alboran and Aegean Seas in order to unravel the climatic variability in the coastal settings of the Mediterranean region between 15 000 and 4000 cal yrs BP (the Lateglacial, and early to mid-Holocene). The quantitative climate reconstructions for the Alboran and Aegean Sea records focus mainly on the reconstruction of the seasonality changes (temperatures and precipitation), a crucial parameter in the Mediterranean region. This study is based on a multi-method approach comprising 3 methods: the Modern Analogues Technique (MAT), the recent Non-Metric Multidimensional Scaling/Generalized Additive Model method (NMDS/GAM) and Partial Least Squares regression (PLS). The climate signal inferred from this comparative approach confirms that cold and dry conditions prevailed in the Mediterranean region during the Heinrich event 1 and Younger Dryas periods, while temperate conditions prevailed during the Bølling/Allerød and the Holocene. Our records suggest a West/East gradient of decreasing precipitation across the Mediterranean region during the cooler Late-glacial and early Holocene periods, similar to present-day conditions. Winter precipitation was highest during warm intervals and lowest during cooling phases. Several short-lived cool intervals (i.e., Older Dryas, another oscillation after this one (GI-1c2), Gerzensee/Preboreal Oscillations, 8.2 ka event, Bond events) connected to the North Atlantic climate system are documented in the Alboran and Aegean Sea records indicating that the climate oscillations associated with the successive steps of the deglaciation in the North Atlantic area occurred in both the western and eastern Mediterranean regions. This observation confirms the presence of strong climatic linkages between the North Atlantic and Mediterranean regions.

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Cyclonic Activity In The Mediterranean Region From A High-Resolution Perspective Using Ecmwf Era5 Dataset

10.21203/rs.3.rs-390147/v1 ◽

2021 ◽

Author(s):

Leonardo Aragão ◽

Federico Porcu'

Keyword(s):

High Resolution ◽

Mediterranean Region ◽

Aegean Sea ◽

Annual Number ◽

Cyclonic Activity ◽

Reanalysis Dataset ◽

Subjective Analysis ◽

Detection And Tracking ◽

The Mediterranean ◽

Resolution Dataset

Abstract This study focuses on developing a new Cyclone Detection and Tracking Method (CDTM) to take advantage of the recent availability of a high-resolution reanalysis dataset of ECMWF ERA5. The proposed algorithm is used to perform a climatological analysis of the cyclonic activity in the Mediterranean Region (MR) into a 40-year window (1979–2018). The tuning of the new CDTM was based on the comparison with currently available CDTMs and verified through careful subjective analysis to fully exploit the finer details of MR cyclones features. The application of the new CDTM to the ERA5 high-resolution dataset resulted in an increase of 40% in the annual number of cyclones, mainly associated with subsynoptic and baroclinic driven lows. The main cyclogenetic areas and seasonal cycle were properly identified into the MR context, including areas often underestimated, such as the Aegean Sea, and emerging new ones with cyclogenetic potential such as the coast of Tunisia and Libya. The better cyclone features description defined three distinct periods of cyclonic activity in the MR with peculiar and persistent characteristics. In the first period (Apr-Jun), cyclones develop more frequently and present higher velocities and deepening rates. In the second (Jul-Sep), the cyclonic activity is governed by thermal lows spreading slowly over short tracks without reaching significant depths. In the last and longest season (Oct-Mar), cyclones become less frequent, but with the highest deepening rates and the lowest MSLP values, ranking this period as the most favourable to intense storms.

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