bluuebunny/crossref_metadata_2025_split huggingface dataset:
Eustatically controlled sedimentation recorded by Eocene strata of the James Ross Basin, Antarctica
Authors: Marenssi Sergio A. 
Published: April 2008

Abstract

The Eocene La Meseta Formation is an unconformity-bounded unit that records the geological evolution of the James Ross Basin, NE Antarctic Peninsula, during a period of decreasing tectonism and a lull in volcanic activity. This unit represents a composite incised valley, filled with deltaic, estuarine and shallow-marine deposits showing a landwards facies shift that indicates deposition during an overall sea-level rise. The six unconformity-based internal units (Valle de las Focas, Acantilados, Campamento,
Cucullaea
I,
Cucullaea
II and Submeseta allomembers) are interpreted to represent minor-scale regressive-transgressive events. Geological, palaeontological and new strontium isotopic ages allow the correlation of base-level changes with second- and third-order eustatic sea-level fluctuations. The base of the La Meseta Formation is correlated with a global 56 Ma lowstand in sea level followed by a main episode of flooding between 54.3 and 52.4 Ma. The base of the
Cucullaea
I Allomember is correlated with the well-known late Ypresian (49 Ma) lowstand, and the base of the Submeseta Allomember with the 36 Ma lowstand. Correlation of Eocene sea-level fluctuations in the northern Antarctic Peninsula with the global sea-level curve strengthens the concept of global syncroneity of the eustatic sea-level curve.
First gondwanatherian mammal from Antarctica
Authors: Goin Francisco J. , Reguero Marcelo A. , Pascual Rosendo , von Koenigswald Wighart , Woodburne Michael O. , Case Judd A. , Marenssi Sergio A. , Vieytes Carolina , Vizcaíno Sergio F. 
Published: April 2008

Abstract

Gondwanatherians are an enigmatic group of extinct non-therian mammals apparently restricted to some of the western Gondwanan continents (Late Cretaceous-early Palaeocene of South America, and Late Cretaceous of Madagascar and India). They developed rodent-like incisors and the earliest known hypsodont cheek-teeth among mammals. Recently, a small rodent-like dentary fragment was recovered from middle Eocene beds on the Antarctic Peninsula, preserving part of the incisor; both the incisor enamel structure and the mandibular morphology suggest close affinities with
Sudamerica ameghinoi
from the early Palaeocene of Patagonia, up to now the youngest known Gondwanatheria. Thus, the new specimen becomes the youngest occurrence of a gondwanathere, adding significant direct and indirect evidence on: (1) the already documented cosmopolitanism of gondwanatheres among Gondwanan mammals; and (2) the crucial biogeographical role of Antarctica during the Cretaceous-Tertiary mammalian transition.
Tectonic development of the Eastern Mediterranean region: an introduction
Authors: Robertson Alastair H. F. , Mountrakis Demosthenis 
Published: April 2008

Abstract
The Eastern Mediterranean is one of the key regions for the understanding of fundamental tectonic processes, including continental rifting, passive margins, ophiolites, subduction, accretion, collision and post-collisional exhumation. It is also ideal for understanding the interaction of tectonic, sedimentary, igneous and metamorphic processes through time that eventually lead to the development of an orogenic belt. Below, we will outline some milestones in the development of tectonic-related research in the Eastern Mediterranean region. We will mention how studies of the Eastern Mediterranean contribute to our understanding of fundamental tectonic processes and indicate how papers in this volume contribute to this aim. Current and emerging research themes will be highlighted. We will also outline the main alternative tectonic reconstructions of the region (see Fig. 1), and mention which of these the different contributors favour. Tethyan nomenclature remains controversial and we will suggest an appropriate informal terminology for the various oceanic basins that existed. An entrée to some of the key literature sources is also provided. Citations here are mainly to edited volumes, which provide access to this large subject area.
Many of the papers in this book integrate and synthesize large amounts of geological information for extended periods of geological time. The papers are ordered in a general time sequence with a view to linking those that consider comparable tectonic setting and processes. The locations of the areas are shown in Figures 2 and 3. Figure 2 also shows the main sutures, and Figure 3 illustrates the main neotectonic elements of the region.
Tethyan ophiolite emplacement, Africa to Europe motions, and Atlantic spreading
Authors: Smith A. G. 
Published: April 2008

AbstractFinal emplacement of the mid-Jurassic and mid-Cretaceous supra-subduction zone (SSZ) ophiolites onto adjacent continental areas in the Mediterranean region is synchronous with reductions in the rate of motion between Africa and stable Europe. The Apennine-Ligurian-Alpine ophiolites lack SSZ chemistry, are mid-ocean ridge basalt (MORB)-like, range in age fromc.169 to 148 Ma, and were emplaced in late Cretaceous and Cenozoic time. The Hellenic-Dinaric SSZ ophiolites include some MORB, ranging from 173 to 168 Ma, and were emplaced, eroded, and covered by younger sediments byc.140 Ma. The creation of the Apennine-Ligurian-Alpine and Hellenic-Dinaric suites is attributed to the motion of Adria, which formed a promontory on Africa, or essentially moved with it, as the central Atlantic opened. Extension to the west of Adria gave rise to the Ligurian Sea, generating MORB crust; to the east, a pre-existing Triassic ocean was subducted, with rollback creating Jurassic SSZ ophiolites that were emplaced onto adjacent continental margins in the later stages of convergence. The two episodes of slower motions between Africa and Europe are attributed to two episodes of attempted subduction of a passive continental margin. This speculation suggests that emplacement of some SSZ ophiolites may exert a significant control on oceanic spreading patterns.
Late Proterozoic and Silurian basement units within the Serbo-Macedonian Massif, northern Greece: the significance of terrane accretion in the Hellenides
Authors: Himmerkus F. , Reischmann T. , Kostopoulos D. 
Published: April 2008

Abstract

The Serbo-Macedonian Massif (SMM) is a large, elongate basement complex in the Internal Hellenides, which stretches from Serbia to the Chalkidiki Peninsula in northern Greece. As a result of similarities in lithology and structural grain, the SMM has long been considered part of the adjacent Rhodope Massif. Recent work, however, based on precise geochronological and geochemical data, has revealed that the SMM is not a homogeneous crustal entity but made up of several crustal units, only one of which is related to the Rhodope Massif. One of these units, the Pirgadikia Unit, occurs as a tectonic sliver in a mélange zone bordering the western margin of the SMM that separates it from the adjacent Vardar Zone. The Pirgadikia Unit consists of leucocratic mylonitic para- and orthogneisses. According to trace-element and Sr-isotope data, the orthogneisses originated in a magmatic arc setting. Dating of this unit by the Pb-Pb single-zircon evaporation method yielded Pan-African ages of 555.8±2.6 Ma on a paragneiss collected near the village of Taxiarchis, and two ages of 570.0±7.0 Ma and 587.6±3.4 Ma on orthogneisses from the quayside at Pirgadikia village. The rocks enveloping this Late Precambrian basement complex are gneisses of the Vertiskos Unit. This unit, which is regarded as a distinct terrane, occupies the northwestern part of the Greek SMM and consists of Silurian orthogneisses with a magmatic arc signature and subordinate metasediments. Orthogneisses of the Vertiskos Unit adjacent to the mylonites of the Pirgadikia Unit gave Pb-Pb ages of between 428.2±1.2 Ma and 433.0±2.1 Ma. One of these samples was additionally dated by the conventional U-Pb method. This sample has three concordant zircon grains confirming a Silurian intrusion age and two inherited cores pointing to an older basement into which precursor rocks to the Silurian gneisses were intruded. The upper intercept of a Concordia plot yielded an age of
c
. 2.5 Ga, which is a common age in the cratons of Gondwana. The Pan-African age of the Pirgadikia Unit and the inherited ages of the Vertiskos Unit support the notion that these units are terranes derived from Gondwana. They were finally accreted to the Hellenic orogen during the closure of one of the branches of the Tethys Ocean. The presence of exotic terranes in the Internal Hellenides contradicts the hypothesis that this part of the Hellenides formed a stable hinterland during the Alpine phase and thus the Hellenides can be considered an accretionary orogen.
Sedimentary evidence from the south Mediterranean region (Sicily, Crete, Peloponnese, Evia) used to test alternative models for the regional tectonic setting of Tethys during Late Palaeozoic-Early Mesozoic time
Authors: Robertson A. H. F. 
Published: April 2008

Abstract
The south Mediterranean region, including western Sicily, Crete and mainland Greece (southern Peloponnese and Evia), is critical to an interpretation of the Late Palaeozoic-Early Mesozoic tectonic evolution of Tethys. Several contrasting tectonic models compete to explain the regional evolution. In a divergence-related hypothesis (Model 1) the south Aegean region experienced pulsed rifting along the northern margin of Gondwana that culminated in break-up to form the Pindos ocean in the region of Greece. In an alternative convergence-related hypothesis (Model 2) the south Aegean experienced Late Palaeozoic Early Mesozoic northward subduction, accretion and arc magmatism, culminating in ‘Cimmerian’ suturing of a Palaeotethyan ocean in latest Triassic time. In a third model, southward subduction of a Palaeotethyan ocean took place beneath the North Gondwana margin during Late Palaeozoic-Triassic time, giving rise to back-arc magmatism in an extensional setting. In addition, a more complex setting involving two opposing subduction zones (Andean-type and intra-oceanic) has also been suggested (Model 4), mainly based on lava geochemistry. To test these tectonic alternatives, mainly sedimentary studies were carried out in western Sicily, western and eastern Crete, the Peloponnese and Evia (eastern central Greece). Western Sicily was studied as a proxy for the unexposed deep Mediterranean south of Crete. Most of the available evidence supports the divergence-related (pulsed rift) hypothesis (Model 1). There is no clear evidence of sea-floor spreading (e.g. ophiolites) to the south of what became the Pindos ocean, or of plate convergence (e.g. magmatic arcs, subduction complexes), or collisional deformation in the south Aegean region that could be related to subduction or collision during the Mid-Carboniferous to Triassic, as in Model 2. Model 3 is not supported by evidence from the wider region (northern Greece, Turkey). Model 4 is not supported by evidence independent of igneous geochemistry. In the proposed interpretation, the northern margin of Gondwana initially rifted during Mid-Carboniferous to Early Permian time to form a wide deep-water basin. This was followed by further rifting, associated with volcanism during the Early Triassic; final continental break-up and spreading to form the Pindos ocean to the north during Late Triassic to Early Jurassic time then followed. Mid-Triassic uplift of part of the rift basin is explained as a flexural response to rifting as a precursor to opening of the Pindos ocean. Passive margin subsidence during the Early Mesozoic relates to opening of the Pindos ocean to the north. A subduction geochemical signature within some Triassic volcanic rocks, in this interpretation, is explained by melting of heterogeneous sub-crustal mantle, following an earlier, possibly Hercynian, subduction event.
Tectonic and sedimentary evolution of the Cenozoic Hatay Graben, Southern Turkey: a two-phase model for graben formation
Authors: Boulton Sarah J. , Robertson Alastair H. F. , Ünlügenç Ulvi C. 
Published: April 2008

Abstract
New structural and sedimentary studies form the basis of a new interpretation for the Neogene Hatay Graben. Fault analysis reveals three contemporaneous trends of fault orientation (000°–180°, 045°–225° and 150°–350°) suggesting that the graben is transtensional in nature. Sedimentary studies show that, following shallow-marine deposition from the Late Cretaceous to the Eocene, a hiatus ensued until Early Miocene fluvial sedimentation. After a Mid-Miocene marine transgression, water depths increased until the Messinian salinity crisis, followed by a regression from the Pliocene to the present day. The basin initially developed as the distal margin of a foreland basin of the Tauride allochthon to the north, developing a classic sedimentary sequence during Mid-Late Miocene. Stresses caused by loading of the crust created a flexural forebulge to the south that supplied sediment mainly northwards. During the Plio-Quaternary, transtensional graben development took place, primarily influenced by the westward tectonic escape of Anatolia along the East Anatolia Fault Zone and left-lateral offset along the northward extension of the Dead Sea Transform Fault. This area is, thus, an excellent example of a foreland basin reactivated in a strike-slip setting. Our new two-phase model: foreland basin, then transtensional basin for the Hatay Graben, is in contrast to previous models, in which it was generally assumed that the Plio-Quaternary Hatay Graben represents a direct extension of the Dead Sea Fault Zone or the East Anatolian Fault Zone.
Multifractal variability in self-potential signals measured in seismic areas
Authors: Telesca Luciano , Lapenna Vincenzo , Macchiato Maria 
Published: April 2008

Abstract

Multifractal variability in the time dynamics of geoelectrical data, recorded in a seismic area of southern Italy, was studied by means of Multifractal Detrended Fluctuation Analysis (MF-DFA), which allows the detection of multifractality in nonstationary signals. Our findings show that the multifractality of the geoelectrical time series recorded in the study area is mainly due to the different long-range correlations for small and large fluctuations. Furthermore, the singularity spectrum has led to a better description of the signal, revealing a clear enhancement of its degree of multifractality (measured by the variation of the standard deviation of the generalized Hurst exponents
h
(
q
) or the Hölder exponents α) in association with the occurrence of the largest earthquake. However, in order to assess significant correlations between large earthquakes and patterns of multifractal parameters, an investigation of data sets covering longer periods and different seismotectonic environments is needed. The study also furnishes details on our approach for investigating the complex dynamics of earthquake-related geoelectrical signals.
A general landslide distribution applied to a small inventory in Todi, Italy
Authors: Turcotte Donald L. , Malamud Bruce D. , Guzzetti Fausto , Reichenbach Paola 
Published: April 2008

Abstract
Large numbers of landslides can be associated with a trigger, for example, an earthquake or a large storm. We have previously hypothesized that the frequency—area statistics of landslides triggered in an event are well approximated by a three-parameter inverse-gamma distribution, irrespective of the trigger type. The use of this general distribution was established using three substantially complete and well-documented landslide event inventories: 11,000 landslides triggered by the Northridge California Earthquake, 4000 landslides triggered by rapidly melting snow cover in the Umbria region of Italy, and 9000 landslides triggered by heavy rainfall associated with Hurricane Mitch in Guatemala. In this paper, we examine further this general landslide distribution by using an inventory of 165 landslides triggered by heavy rainfall in the region of Todi, Central Italy. Our previous studies have shown the applicability of our general landslide distribution to events with 4000–11,000 landslides. This smaller inventory provides a critical step in examining the applicability of the general landslide distribution. We find very good agreement of the Todi event with our general distribution. This also provides support for our further hypothesis that the mean area of landslides triggered by an event is approximately independent of the event size.
Power-law extreme flood frequency
Authors: Kidson R. , Richards K. S. , Carling P. A. 
Published: April 2008

Abstract
Conventional Flood Frequency Analysis (FFA) has been criticized both for its questionable theoretical basis, and for its failure in extreme event prediction. An important research issue for FFA is the exploration of models that have theoretical/explanatory value as the first step towards more accurate predictive attempts. Self-similar approaches offer one such alternative, with a plausible theoretical basis in complexity theory that has demonstrable wide applicability across the geophysical sciences. This paper explores a simple self-similar approach to the prediction of extreme floods. Fifty river gauging records from the USA exhibiting an outlier event were studied. Fitting a simple power law (PL) relation to events with return period of 10 years or greater resulted in more accurate discharge and return period estimates for outlier events relative to the Log-Pearson III model. Similar success in predicting record events is reported for 12 long-term rainfall records from the UK. This empirical success is interpreted as evidence that self-similarity may well represent the underlying physical processes generating hydrological variables. These findings have important consequences for the prediction of extreme flood events; the PL model produces return period estimates that are far more conservative than conventional distributions.
Models, data and mechanisms: quantifying wildfire regimes
Authors: Millington James D. A. , Perry George L. W. , Malamud Bruce D. 
Published: April 2008

Abstract
The quantification of wildfire regimes, especially the relationship between the frequency with which events occur and their size, is of particular interest to both ecologists and wildfire managers. Recent studies in cellular automata (CA) and the fractal nature of the frequency-area relationship they produce has led some authors to ask whether the power-law frequency-area statistics seen in the CA might also be present in empirical wildfire data. Here, we outline the history of the debate regarding the statistical wildfire frequency-area models suggested by the CA and their confrontation with empirical data. In particular, the extent to which the utility of these approaches is dependent on being placed in the context of self-organized criticality (SOC) is examined. We also consider some of the other heavy-tailed statistical distributions used to describe these data. Taking a broadly ecological perspective we suggest that this debate needs to take more interest in the mechanisms underlying the observed power-law (or other) statistics. From this perspective, future studies utilizing the techniques associated with CA and statistical physics will be better able to contribute to the understanding of ecological processes and systems.
‘Transgressive washing’ concept: a sequence stratigraphic approach for calci- and siliciclastic turbidites
Authors: El Kadiri Kh. , Chalouan A. , Bahmad A. , Salhi F. , Liemlahi H. 
Published: April 2008

Abstract
Carbonate breccias, calciturbidites and sandstone flysch sediments are typically assigned to the lowstand regime, based on the double assumption that these thick sedimentary packages necessitate (1) emergence phases for the production of their terrigenous material, and (2) a relatively lower position of the shoreline, which did not lie too far from the shelf-break line. In strictly regarding these conditions, we can run the risk of neglecting the role played by the transgression-related currents in reworking and exporting basinward bioclastic and siliciclastic sands from shelves. The ‘transgressive washing’ concept proposed here accounts for the latter mechanism, particularly in the case when the stratigraphic record shows that the onset of both the calci- and siliciclastic material was contemporaneous with newly marine-encroached continental source areas. Four examples from the Rifian internal (source) and external zones (basin) are presented to illustrate this phenomenon.
Mauretanian flysch nappe in the northwestern Rif Cordillera (Morocco): deformation chronology and evidence for a complex nappe emplacement
Authors: Chalouan A. , El Mrihi A. , El Kadiri Kh. , Bahmad A. , Salhi F. , Hlila R. 
Published: April 2008

Abstract
This study deals with the Mauretanian flysch nappe in the southern side of the Gibraltar Strait, NW of the Rif belt (Morocco), where it is possible to better appraise the stacking pattern of its two structural components (the Tisirene and Béni Ider nappes), and to decipher the chronology of deformation and its structural relationships with the overlying (Predorsalian and Numidian nappes) and the underlying nappes (Melloussa and Intrarif units). It is found that the main deformations were produced by an intermittent compressional regime, during which north-south- to NW-SE-directed compressional phases alternated with ENE-WSW to east-west-directed compressional ones. Whereas the former were generated by the Africa-Iberia convergence and resulted in small-scale thrusts and a brittle deformation style, the latter were driven by the west-drifting Alboran plate and resulted in paroxysmal fold-thrust deformations. Field evidence shows that the emplacement of the Mauretanian nappe over the Massylian one and the Intrarif units operated by inter-related compressional and gravitational processes, by virtue of which the majority of nappes stacked in an out-of-sequence regime. The precise age of the paroxysmal phases remains uncertain because of paucity or absence of direct stratigraphical data. However, this structural evolution is likely to have started as early as the mid-Burdigalian, when sedimentation synchronously ceased in the flysch trough. Its final phases may be placed precisely between the Langhian (N8) age of the most recent formations overlapped by these nappes and the late Tortonian age of the oldest formations transgressively covering them.