bluuebunny/crossref_metadata_2025_split huggingface dataset:
Late Cretaceous-Early Cenozoic tectonic evolution of the Eurasian active margin in the Central and Eastern Pontides, northern Turkey
Authors: Rice Samuel P. , Robertson Alastair H. F. , Ustaömer Timur 
Published: April 2008

Abstract
The Izmir-Ankara-Erzincan suture zone (IAESZ) in the Central and the Eastern Pontides comprises a stack of thrust sheets of mainly Late Cretaceous-Early Cenozoic age that are restored as: (1) a subduction-accretion complex; (2) a continental-margin magmatic arc, plus an associated forearc basin; (3) a back-arc basin and its mainly sedimentary fill. Northward thrusting affected all of the Late Cretaceous units during latest Cretaceous (Campanian-Maastrichtian) time. This was followed by regional southward thrusting to form the present thrust stack during Mid-Eocene time. Alternative tectonic models are considered in the light of sedimentary, igneous geochemical and structural evidence, and global comparisons. We infer that the Northern Neotethys was subducted northwards beneath the Eurasian active margin during the Late Cretaceous. Subduction was associated with the genesis of a magmatic arc and a related forearc basin. The subduction zone retreated oceanwards, associated with the opening of a back-arc basin along the Eurasian margin, floored by oceanic crust and overlain by mixed terrigenous and volcaniclastic deep-marine sediments. Ophiolite genesis in a continental margin back-arc setting is suggested by the presence of screens of basement-type metamorphic rocks within an ophiolite-related sheeted dyke complex in the Eastern Pontides. During the latest Cretaceous closure of the inferred back-arc basin resulted in northward emplacement of ophiolitic and related units onto the Eurasian margin, as well exposed in the Central Pontides. In addition, accretionary mélange, volcanic arc, forearc and ophiolitic units were emplaced southwards onto the Tauride continent, represented by the Munzur platform in the Eastern Pontides, also during latest Cretaceous time. This incipient (‘soft’) collision was followed by widespread Paleocene-Early Eocene deposition of Nummulitic shelf carbonates and coarse clastic sediments on deformed and emplaced accretionary mélange, arc and ophiolitic units. Final closure (‘hard collision’) of the Northern Neotethys occurred during the Mid-Eocene, resulting in large-scale southward imbrication, together with northward backthrusting in some areas. Suture tightening and Plio-Quaternary strike-slip ensued.
Geometry and structural evolution of the Mesohellenic Trough (Greece): a new approach
Authors: Vamvaka A. , Kilias A. , Mountrakis D. , Papaoikonomou J. 
Published: April 2008

Abstract
The Mesohellenic Trough (MHT) is an elongate basin parallel to the Hellenide isopic zones that extends from southern Albania through northern Greece. The basin developed from Mid-Late Eocene to Mid-Late Miocene time related to Alpine orogenic processes. Structural and kinematic evidence shows that the MHT developed in response to successive tectonic events, involving isostatic crustal flexure, strike-slip and normal faulting, all related to inferred oblique convergence of the Apulian and Pelagonian microcontinents. The Mesohellenic Trough evolved as a piggyback basin above westward-emplacing ophiolites and higher Pelagonian units. This differs from previous interpretations that envisaged foreland flexure related to backthrusting, or subsidence associated with asymmetrical flexure, or normal faulting. The first stage of basin development during the Mid-Late Eocene was contemporaneous with the final emplacement of Pindos oceanic units and culminated in deformation and uplift of Eocene strata. The second phase was dominated by strikeslip faulting during Oligocene-Early Miocene time. The third stage was characterized by low-angle normal faulting at the eastern boundary of the MHT during the Early-Late Miocene. The evolution of the sedimentary basin ended around Late Miocene time, followed by rapid uplift and marine regression. A compressional event occurred during the latest Miocene. Finally, extensional tectonics affected the area from the Late Miocene to the present.
First results of fission-track thermochronology in the Albanides
Authors: Muceku Bardhyl , Mascle Georges H. , Tashko Artan 
Published: April 2008

Abstract
Albania, situated at the boundary between the Dinaric and the Hellenic branchs of the Dinaro-Hellenic fold belt, has experienced a multiphase geodynamic evolution. The internal zones show a Mid-Jurassic episode of deformation characterized by ophiolite obduction, followed by development of a fold-and-thrust belt in the external zones during the Cenozoic. More recently, Albania has experienced a tensional regime. We present apatite and zircon fission-track (AFT and ZFT) measurements for 22 samples, and seven measurements of track-length distributions to elucidate the thermal evolution. AFT ages vary from 10.8 ± 0.7 Ma to 50.5 ± 5.7 Ma. The oldest ages (Eocene) occur in the western Albanides, corresponding to Eocene emplacement of the internal zones over the external ones. Neogene ages in the eastern Albanides suggest rapid exhumation, which we relate to an extensional regime. The ZFT ages show that the internal Albanides did not reach temperatures > 200 °C during the Cenozoic.
Perspectives for earthquake prediction in the Mediterranean and contribution of geological observations
Authors: Papazachos B. C. , Karakaisis G. F. , Papazachos C. B. , Scordilis E. M. 
Published: April 2008

Abstract

Accelerating seismic strain caused by the generation of intermediate-magnitude preshocks in a broad (critical) region, accompanied by decelerating seismic strain caused by the generation of smaller preshocks in the seismogenic region are systematically observed before strong mainshocks. On the basis of this seismicity pattern a model has been developed that seems promising for intermediate-term earthquake prediction, called the ‘Decelerating in-Accelerating out Seismic Strain Model’. Recent seismological data for the Mediterranean region are used here for backward and forward testing of this model. The selection of the broader Mediterranean region as a test area was motivated not only by the interest of time-dependent seismic hazard assessment in a high-seismicity and highly populated region but also by the fact that the Mediterranean is a natural geophysical and geological laboratory where both complex multi-plate and continuum tectonics are found in a more or less convergent zone. Within this complex geotectonic setting several geological phenomena such as subduction, collision, orogen collapse and back-arc extension take place, leading to the generation of a broad spectrum of mainshocks, reaching M
W
= 8.0 or greater for subduction-related thrust events and a variety of corresponding seismicity levels and neotectonic activity ranging from very low (e.g. large parts of Iberian peninsula) to very high (broader Aegean area). The backward procedure shows that all six strong (M ≥ 6.8) mainshocks that have occurred in the Mediterranean since 1980 had been preceded by preshock sequences that followed this seismicity pattern and satisfy all model constraints. Application of the model for future mainshocks has led to the identification of nine regions (in the Pyrenees, Calabria, NE Adriatic, Albania, Northern Greece, SE Aegean, NW Anatolia, western Anatolia, NE Anatolia) where current intermediate-magnitude seismicity satisfies the constraints of the model and corresponds to strong (M ≥ 6.2) mainshocks. The magnitudes, epicentres and origin times of these probably ensuing mainshocks, as well as their corresponding uncertainties, are estimated, so that it is possible to evaluate the model potential during the next decade (2006–2015). Furthermore, it is shown that geological observations of surface fault traces can contribute to the accurate location of the foci of future strong mainshocks in the Mediterranean and to an estimation of their sizes. For this purpose, globally valid relations between fault parameters based on geological observations (surface fault length,
L
S
, and fault slip,
u
S
) and measures of mainshock size (mainshock magnitude, subsurface fault length,
L
, and fault slip,
u
) are proposed.
An inverse cascade explanation for the power-law frequency-area statistics of earthquakes, landslides and wildfires
Authors: Malamud Bruce D. , Turcotte Donald L. 
Published: April 2008

Abstract
Frequency-magnitude statistics for natural hazards can greatly help in probabilistic hazard assessments. An example is the case of earthquakes, where the generality of a power-law (fractal) frequency-rupture area correlation is a major feature in seismic risk mapping. Other examples of this power-law frequency-size behaviour are landslides and wildfires. In previous studies, authors have made the potential association of the hazard statistics with a simple cellular-automata model that also has robust power-law statistics: earthquakes with slider-block models, landslides with sandpile models, and wildfires with forest-fire models. A potential explanation for the robust power-law behaviour of both the models and natural hazards can be made in terms of an inverse-cascade of metastable regions. A metastable region is the region over which an ‘avalanche’ spreads once triggered. Clusters grow primarily by coalescence. Growth dominates over losses except for the very largest clusters. The cascade of cluster growth is self-similar and the frequency of cluster areas exhibits power-law scaling. We show how the power-law exponent of the frequency-area distribution of clusters is related to the fractal dimension of cluster shapes.
Crustal stress crises and seismic activity in the Italian peninsula investigated by fractal analysis of acoustic emission, soil exhalation and seismic data
Authors: Paparo Gabriele , Gregori Giovanni P. , Poscolieri Maurizio , Marson Iginio , Angelucci Francesco , Glorioso Giorgia 
Published: April 2008

Abstract

Crustal stress can be monitored by acoustic emissions (AE, ultrasound), which give an indication of whether a physical system is subject to stress, either of tectonic or endogenous origin. AE intensity critically depends on the damping of the signal; however, AE signals are clear indicators of the fatigue state of the crustal structures constituting the AE source. This aspect can be studied by fractal analysis of AE time series; these are, however, not suited for earthquake forecasting, as they only denote a changing state involving large lithospheric volumes. Several case histories from Italy show that an increased high-frequency AE activity (200 kHz) occurs approximately seven to eight months in advance of large earthquakes that affect areas of a few hundred kilometres radius, and an increased low-frequency AE activity (at 25 kHz) is observed several weeks in advance. Low-frequency AE also correlate with soil exhalation (water-well chemistry) and CH
4
, whereas fractal analysis of AE signals recorded close to a ‘future’ epicentral area gives a clear indication of the evolution of the system from about two months before the mainshock. This suggests that systematic monitoring of crustal stress variations may be used for assessing the time evolution of seismic activity.
Crustal stress and seismic activity in the Ionian archipelago as inferred by satellite- and ground-based observations, Kefallinìa, Greece
Authors: Poscolieri Maurizio , Lagios Evangelos , Gregori Giovanni P. , Paparo Gabriele , Sakkas Vassilis A. , Parcharidis Issaak , Marson Iginio , Soukis Konstantinos , Vassilakis Emmanuel , Angelucci Francesco , Vassilopoulou Spyridoula 
Published: April 2008

Abstract
Different observational techniques are compared in order to investigate possible correlations in seismic activity. The study site is the island of Kefallinà (Greece), where measurements available included (1) DInSAR, DGPS, and DEM data, (2) soil exhalation measured by monitoring Radon (Rn) well content, and (3) acoustic emissions (AE) at high and low frequency (point-like records with high temporal resolution). AE records provide: (1) relative time variation of the applied stress intensity and (2) the state of fatigue of stressed rock volumes, the AE source. Our results indicate that the large spatial scale (poor time resolution) may be considered quite satisfactory, whereas fractal analysis of the AE time series displayed some discrepancies when compared to analogous investigations in the Italian Peninsula. Therefore, some refinement is needed in order to reach more precise interpretations of the relevant information available with this kind of data. However, both sets of observations appear in agreement with each other, although more exhaustive investigations would require a suitable array of point-like AE and Rn (or other) measuring sites, as well as longer data series. The latter are particularly helpful for detailed interpretations of the different occurrences within tectonically complex settings where crustal stress crises are marked by various types of geological phenomena.
Nonlinear Science issues in the dynamics of unstable rock slopes: new tools for rock fall risk assessment and early warnings
Authors: Zvelebil Jiří , Paluš Milan , Novotná Dagmar 
Published: April 2008

Abstract
Time series of displacement data from unstable rock slopes contain ‘hidden’ information about the dynamics of slope failure. This information cannot be found when using the current linearly causal paradigm based on analytical methods, but is revealed when numerical and graphical methods from the toolbox of the Nonlinear Sciences are applied. The occurrence of fractal patterns, which suggests a qualitative difference between intrinsic slope movement dynamics of time series from the near-to-equilibrium and the far-from-equilibrium dynamical states of slope failure systems, is an example of such a ‘hidden’, diagnostically important indicator. It helps to identify the stage of immediate danger of rock fall occurrence, just in time to launch an efficient early warning. Phase portrait and correlograms of time series proved to be suitable for earlier revelation of transitions from the near-to-equilibrium to the far-from-equilibrium dynamical states, as well as for helping to distinguish between intrinsic slope movement dynamics and climatically driven reversible deformation activity.
Aptian sedimentation: an example of interaction between tectonics and eustatics in Central Tunisia
Authors: Chaabani Fredj , Razgallah Salwa 
Published: April 2008

Abstract
To reconstruct the sequence evolution and distribution of deposits during the Aptian in the Central Tunisian platform, the present study was mainly based on a sedimentological approach. The palaeogeographical reconstruction shows an inner and an external platform separated by the highs of the Central Tunisian islands. These are characterized by carbonate-dominated deposits evolving towards the north into a pelagic marl-dominated sedimentation. The NW-SE-to east-west-directed faults show an important sedimentary control. In fact, a system of tilted blocks located towards the SW characterizes a large part of the platform. The subsidence evolution during the Aptian was marked by a recovery of extensional tectonics. Finally, some halokinetic vertical movements were responsible for several highs during the latest Barremian. The Central Tunisian platform evolution was controlled by drift of the African platform during the opening of the Atlantic Ocean.
Fluid geochemistry versus tectonic setting: the case study of Morocco
Authors: Tassi F. , Vaselli O. , Moratti G. , Piccardi L. , Minissale A. , Poreda R. , Delgado Huertas A. , Bendkik A. , Chenakeb M. , Tedesco D. 
Published: April 2008

Abstract

This paper presents the results of an extensive chemical and isotopic investigation on natural thermal and cold fluids (spring waters and associated gases) discharging throughout the main geological domains of Morocco. The chemical features of the thermal springs are mainly dependent on rock dissolution involving Triassic evaporite formations, producing either Na-Cl or Ca-SO
4
composition, although mixing with shallower connate high-saline waters in Neogene post-orogenic sedimentary layers cannot be ruled out. Only in the Moroccan Meseta and Anti-Atlas domains have spring discharges probably undergone equilibration as a result of water-rock interaction in granites. Of the chemical and isotopic features of the gas seeps,
3
He/
4
He ratios and δ
13
C-CO
2
values indicate the occurrence of a significant contribution of mantle-derived gas, especially at Oulmès (Moroccan Meseta) and Tinejdad-Erfoud (Anti-Atlas), where associated waters are found to equilibrate at relatively high temperatures (
c.
130 °C). These areas are also characterized by the presence of Pliocene to Quaternary basaltic volcanic rocks. Thermal discharges located along the Rif front and related to the NE-SW-oriented main strike-slip faults are associated with a CH
4
- and/or N
2
-rich gas phase, derived respectively from a crustal or an atmospheric source. Some of them have significant contents of
3
He that could indicate the rising of mantle fluids. Such a striking isotopic signature, which is not related to any recent volcanism visible at surface, is likely to be associated with cooling magma at depth related to transpressive fault systems. Similarly, in the northeastern area, the small, although significant, enrichment of
3
He in the gas discharges seeping out along the Nekor seismic active fault and related to Pliocene-Quaternary basalts also suggests a deep-seated (magmatic) contribution. The distribution of thermal discharges is strongly related to the main active tectonic structures of Morocco. Moreover, this study indicates the presence of deep active tectonic structures in areas until now considered as stable. In particular, the NE-SW-trending Nekor fault may be part of a major system that extends to the Moroccan Meseta and into the Smaala-Oulmès fault system, thus emerging as a deep structure with crustal significance.
Chronology of the Middle-Upper Pliocene succession in the Strongoli area: constraints on the geological evolution of the Crotone Basin (Southern Italy)
Authors: Capraro L. , Consolaro C. , Fornaciari E. , Massari F. , Rio D. 
Published: April 2008

Abstract

The aim of this study is to reconstruct the evolution of the Strongoli area, a critical sector of the Crotone Basin (Calabria, Southern Italy), where a thick Middle-Upper Pliocene marine succession is present. The Strongoli succession shows prominent changes in the sedimentary environment that are partly forced by tectonics. Major tectonostratigraphic events have been recognized that might correlate with spreading pulses in the back-arc Tyrrhenian Sea. In particular, we demonstrate that a dramatic basinal collapse at
c.
2.3 Ma correlates with the so-called ‘Calabrian transgression’
Auctorum
and is close in age to the oceanization of the Marsili Basin.
Active faults and inferred seismic sources in the San Vito lo Capo peninsula, northwestern Sicily, Italy
Authors: Tondi E. , Zampieri D. , Giunta G. , Renda P. , Alessandroni M. , Unti M. , Giorgianni A. , Cello G. 
Published: April 2008

Abstract
Two independent active faults, capable of generating medium-sized earthquakes in the San Vito lo Capo peninsula, northwestern Sicily (Italy) have been identified as a result of detailed field studies. In western Sicily, instrumental seismicity is low; in fact, except for the 1968 Belice earthquake (Ms = 5.4), historical records indicate that this area is relatively quiescent. Most of the seismicity is in the offshore sector of the Sicilian Maghrebian Chain, which is characterized by several medium- to low-magnitude events. The main shock of the 2002 Palermo seismic sequence (Mw = 5.9) represents the largest earthquake felt in the area in recent years. The deformation pattern characterizing the most recent faults mapped in northwestern Sicily includes a grid of high-angle faults consisting of major east-west-striking right-lateral and north-south-striking left-lateral features. This fault grid is related to a regional transcurrent right-lateral shear zone, here named the UEKA shear zone, bounded to the north by the Ustica-Eolie fault and to the south by the Kumeta-Alcantara fault. The UEKA shear zone accommodates the regional strain induced by the current stress field acting in the area, which, as emerges from both structural and seismological data, is characterized by a NW-SE-striking main compression.
Characterization of permeability distributions in six lithofacies from the Helsby and Wilmslow sandstone formations of the Cheshire Basin, UK
Authors: Bloomfield J. P. , Moreau M. F. , Newell A. J. 
Published: April 2008

Abstract
The lithofacies and permeability structure of the Abbey Wood borehole, near Delamere, Cheshire, UK, have been investigated so that permeability distributions can be established for characteristic sandstone lithofacies in the Permo-Triassic sandstone aquifer. The borehole penetrates the Helsby Sandstone and Wilmslow Sandstone formations and six major facies (coarse- and fine-grained fluvial channel fill sandstones, sandy sabkha, sand sheet and dune aeolian sandstones, and a massive sandstone facies) and one minor lithofacies, a mudstone facies, have been identified. The permeability distributions for each lithofacies show subtle systematic differences. The two fluvial sandstone facies and the massive sandstone facies have systematically lower permeabilities than the aeolian sandstones, and within the aeolian sandstones the sand sheet and dune sandstones appear to be systematically more permeable than the sabkha facies. Statistical tests on the permeability distributions of each facies indicate that the distributions are statistically distinct and so support the lithofacies classification.
Towards understanding the Dumfries Basin aquifer, SW Scotland
Authors: Akhurst M. C. , Ball D. F. , Brady L. , Buckley D. K. , Burns J. , Darling W. G. , MacDonald A. M. , McMillan A. A. , Ó Dochartaigh B. É. , Peach D. W. , Robins N. S. , Wealthall G. P. 
Published: April 2008

Abstract
The Dumfries Basin aquifer supports groundwater abstraction for public supply, agriculture and industry. Abstraction is concentrated in the western part of the basin, where falling groundwater levels and deteriorating water quality both reflect the effects of intense pumping. There are two bedrock units: a predominantly breccia-coarse sandstone sequence in the west, interfingering with a predominantly sandstone sequence in the NE and east. The basin is bounded by weakly permeable Lower Palaeozoic rocks, and is largely concealed by variable superficial deposits. Surface water flows onto the basin from the surrounding catchment via the Nith and the Lochar Water and their respective tributaries. Direct rainfall recharge occurs via superficial sands and gravels, especially in the north, and discharge is predominantly to the rivers in the central area rather than the sea. A picture is developing of two main aquifer types within the basin: the high-transmissivity western sector underlain by a fracture-flow system with younger water and active recharge and a high nitrate content, compared with the east where groundwater residence times are longer and the storage capacity is higher.