bluuebunny/crossref_metadata_2025 huggingface dataset:
Geochemistry and petrology of a Middle Tithonian limestone-marl rhythmite in the Neuquén Basin, Argentina: depositional and burial history
Authors: Scasso R. A. , Alonso M. S. , Lanés S. , Villar H. J. , Laffitte G.
Published: April 2008

The Middle Tithonian Los Catutos Member (Vaca Muerta Formation, Neuquén Basin), is lithologically and geochemically similar to limestone-marl alternations from the Late Jurassic of the northern hemisphere. Both marls and limestones are pelbiomicrites and biopelmicrites principally composed of pellets, radiolaria, forams, ostracods, equinoids, spicules of sponges and gastropods, cemented by several generations of calcite cement. Smectite and interlayers are the major epiclastic components of the fraction below 2 μm, reflecting pedogenic processes developed on volcanogenic source rocks. More abundant kaolinite in some marls reflects stronger humid conditions in the source area and enhanced terrigenous supply. Al
2
O
3
content is demonstrated to be a reliable indicator of clastic input. The same is not true for silica, often related to high biogenic productivity of siliceous organisms. Rocks show total organic carbon (TOC) contents up to 1.95% and constitute regular to good sources for hydrocarbons, although thermally immature. Rhythmites formed gently sloping mounds accumulated in a distal submarine ramp under low-energy and poorly oxygenated open-sea conditions. Sedimentation rates were high due to high productivity on the sea surface, and supply of terrigenous and carbonate sediments transported by suspension plumes originated in shallow, photic areas. δ
13
C values correspond well with the published curves for the Tithonian sea water and with other records from Tethyan limestones. A preliminary analysis of negative excursions of δ
13
C point to a productivity crisis or a mixture of water layers in a stratified sea with a periodicity of 400 ka, which could be a result of changes in the orbital eccentricity of the Earth. Light isotopic composition of O in bulk rocks is the result of diagenetic neomorphism and cement precipitation. Calculated palaeotemperatures from δ
18
C are consistent with those derived from measured vitrinite reflectance (
Ro%
) and burial history reconstruction. Data indicate initial burial during the Tithonian extending up to the Lower Cretaceous, a short period of uplift (Intravalaginian tectonic phase), and renewed uplift during the Cenomanian followed by significant Late Cretaceous sedimentation and Pliocene thrusting.
Hemipelagic record of orbitally-induced dilution cycles in Lower Cretaceous sediments of the Neuquén Basin
Authors: Sagasti Guillermina
Published: April 2008

The lower Valanginian-lower Barremian Agrio Formation in the Mendoza region of the Neuquén Basin (Argentina) accumulated in a hemipelagic outer ramp/basin setting. The formation records the alternation of periods of fine-grained carbonate accumulation and periods of fine-grained clastic deposition, which resulted in a strongly rhythmic succession in which dark clastic hemicycles alternate with light carbonate hemicycles. Clastic and carbonate hemicycles show distinct geochemical signatures that reflect cyclic fluctuations in terrigenous influx to the basin. Clastic hemicycles have relatively high percentages of Fe, Al and K, and less than 60% CaCO
3
, whereas carbonate hemicycles contain relatively low quantities of detrital elements (Fe, Al and K), and more than 60% CaCO
3
. Fluctuations in terrigenous supply to the basin occurred in response to the alternation between two contrasting climate regimes and resulted in the formation of dilution cycles. Warm temperate (winter-wet) climate conditions led to the accumulation of clastic hemicycles, whereas arid conditions promoted the deposition of carbonate hemicycles. The ultimate mechanism that controlled the alternation of the dark and light intervals was orbital forcing, as the latitudinal shifting of climate zones was driven by the
c
. 21 000 years precessional cycle.
Jurassic marine reptiles of the Neuquén Basin: records, faunas and their palaeobiogeographic significance
Authors: Gasparini Zulma , Fernández Marta
Published: April 2008

The largest diversity of Jurassic marine reptiles from Gondwana has been recorded in the Neuquén Basin. Although the Early Jurassic records are limited, the records from the Middle Jurassic, especially the early Bajocian plesiosaurs and ichthyosaurs, are unique in the world. The highest abundance and taxonomic diversity is recorded from the Late Jurassic (Tithonian). Pleurodiran (Notoemys) and cryptodiran turtles (Neusticemys), ichthyosaurs (Ophthalmosaurus, Caypullisaurus), pliosaurs (Pliosaurus, Liopleurodon) and crocodilians (Geosaurus, Metriorhynchus, Dakosaurus) are members of this rich marine herpetofauna. Except for Notoemys, the other reptiles are pelagic. Their habits and large size (Caypullisaurus, Liopleurodon, Dakosaurus) suggest that they entered the sheltered Neuquén Basin occasionally, possibly for reproduction in protected areas. The model of a protected basin, open to the Pacific Ocean through gaps in an emergent by island-arc complex, fits well with the ecological requirements inferred for most of the pelagic reptiles. The Caribbean Corridor may also have played a significant role as a seaway at least during the Middle Jurassic and probably before. New findings in Tithonian and Berriasian sediments of the Neuquén Basin suggest that there was no massive extinction among the marine herpetofauna at the Jurassic-Cretaceous boundary.
Lithofacies, palaeoecology and palaeoenvironments of the Agrio Formation, Lower Cretaceous of the Neuquén Basin, Argentina
Authors: Lazo Darío G. , Cichowolski Marcela , Rodríguez Débora L. , Aguirre-Urreta M. Beatriz
Published: April 2008

The lithofacies and macrofossil guilds of the Agrio Formation (Upper Valanginian—Lower Barremian) have been analysed using evidence from sedimentological, taphonomic and palaeoecological studies. The study area is Agua de la Mula and adjacent regions in central Neuquén. Seven lithofacies have been recognized in the field, which indicate that the Agrio Formation was deposited in an open-marine, ramp depositional system under storm influence. Lithofacies indicate conditions that range from low-energy basin to high-energy inner ramp. Outer and mid-ramp deposits are the most abundant. Macrofossils have been grouped into 16 guilds based on tiering, life habit and feeding category. The guilds indicate normal benthic oxygen level, normal salinity, and soft—firm muddy and sandy bottoms. Suspension-feeders are more common than deposit-feeders suggesting the predominance of suspended food particles over deposited food resources. A low input of siliciclastics and, possibly, other palaeoceanographic conditions allowed the development of oolitic facies in the inner ramp and coral patch reefs in the upper mid-ramp for a limited period of time.
Surface topography and internal strain variation in wide hot orogens from three-dimensional analogue and two-dimensional numerical vice models
Authors: Cruden Alexander R. , Nasseri Mohammad H. B. , Pysklywec Russell
Published: April 2008

The post-accretionary deformation of wide, hot orogens is characterized by pure-shear or transpressional shortening of relatively weak lithosphere (the orogen) between converging stronger blocks (the vice). We report on a series of analogue vice models and compare the resulting three-dimensional strain fields and surface topographies to equivalent two-dimensional numerical experiments. In the analogue models a rheologically stratified (frictional/viscous) weak orogenic lithosphere overlying a viscous asthenosphere is squeezed between converging strong lithospheric blocks. Ductile lower crust and mantle in the weak lithosphere is free to flow laterally, parallel to the orogen. The Argand number describes the model dynamics and strongly controls both the orogenic relief and the degree of lower crustal orogen parallel stretching in the analogue models. Cross sections of numerical and analogue experiments display consistent geometries in which upper crustal deformation is characterized by upright folding compared to apparently decoupled horizontal strains in the lower crust. The relative buoyancy and degree of orogen parallel flow in the lower crust of the analogue models has a dramatic influence on three-dimensional strain fields and the kinematics of upper crustal curvilinear shear zones. The analogue and numerical results demonstrate the importance of three-dimensional effects in determining the structure of natural orogens and compare favourably to field and geophysical observations of large hot orogens in the geological record.
Inversion of a symmetric basin: insights from a comparison between analogue and numerical experiments
Authors: Panien M. , Buiter S. J. H. , Schreurs G. , Pfiffner O. A.
Published: April 2008

We use both analogue and numerical experiments to study the inversion by shortening of a symmetric sedimentary basin. The combination of the two modelling techniques uses the strengths of each method to provide insight into basin-inversion processes. The experiments start with a pre-existing basin filled, in part, with weak layers simulating weak sedimentary rocks. Both footwall and hanging wall can deform freely. The physical properties of the materials used in the analogue experiments (sand and microbeads) and the numerical experiments are appropriately scaled to represent upper crustal rocks. We present a systematic study of the effects of basin infill, basin width and basin location and a sensitivity analysis to understand the effects of the boundary conditions. The results of both methods show that the graben fill accommodates most shortening. Weak layers play an important role in localising shortening with limited reactivation of pre-existing (but weakened) faults. In general, forward thrusts and back thrusts nucleate at the lateral contrast of strong and weak materials and cut across the graben-bounding faults. Weak basal detachments are required to transfer shortening to the basin region. The overall evolution of the analogue and numerical models is encouragingly similar.
Recent advances and current problems in modelling surface processes and their interaction with crustal deformation
Authors: Braun Jean
Published: April 2008

I present a brief summary of recent advances in the field of computational geomorphology and various attempts to couple numerical models of landscape evolution to models of crustal/lithospheric deformation. The most commonly used formulations for the various physical processes at play during surface erosion, transport and deposition are presented, as well as an outline of how they have been incorporated in a variety of numerical schemes. I also explain how the coupling between erosion and tectonics has been performed under various simplifying assumptions. Determining the rate constants for each of the proposed landforming mechanisms remains a difficult challenge that has recently been helped by the advent of new low temperature thermochronometers and exposure dating by cosmogenic radionuclides. I demonstrate how the information contained in the relationship between age and elevation can be used to provide constraints on the ‘age’ of a landscape, as well as how important rate information can be extracted from various datasets by using simple modelling techniques. This paper demonstrates why the field of computational geomorphology needs to harmonize the various parameterizations (often the legacy of empirical relationships derived from observations at the human scale), quantitative estimates of the value of the numerous rate parameters and improvement of the numerical techniques.
The deliberate search for the stratigraphic trap: an introduction
Authors: Allen Matthew R. , Goffey Graham P. , Morgan Richard K. , Walker Ian M.
Published: April 2008

This Special Publication draws upon contributions to a similarly titled conference ‘The Deliberate Search for the Stratigraphic Trap — Where Are We Now?’ held at the Geological Society in London during 2004. Observations in this introductory paper have been drawn from the authors’ experience, talks given at the conference and papers within this volume. Specifically it is noted that by analogy to basins which are perceived to be mature for structural traps, stratigraphic traps can have substantial remaining potential. Additionally, current exploration for stratigraphic traps seems rather restricted to areas where seismic data allow the direct assessment of fluid fill and reservoir development. It is argued that the industry is probably not doing enough to learn from established stratigraphic traps to guide future exploration for such traps. Looking forward, it is suggested that the industry faces two key challenges. Firstly, the use of all available data to assess fluid type and reservoir presence in areas of unfavourable rock physics, and secondly, the development of sufficiently sophisticated predictive models of stratigraphic trap development.
Evaluating subtle stratigraphic traps: prospect to portfolio
Authors: Binns P. E.
Published: April 2008

A compilation of 85 stratigraphic traps demonstrates the variety of trapping mechanisms and the scope for developing new concepts by matching geological models with features in 3D seismic volumes. However, aspects of quantitative evaluation may discourage exploration. Investors require assurance in the form of probabilistic evaluations of risk and value but information critical to the evaluation of new stratigraphic concepts is likely to be lacking. As estimates of risk and uncertainty vary with information, prospects evaluated with radically different levels of information must be ranked with care. The requirements for quantitative project ranking and portfolio optimization have to be reconciled with the need to ‘venture into the unknown’. The character of stratigraphic prospects dictates different evaluation methods from those used to evaluate structural prospects. This, together with the high degree of sensitivity of value to evaluation methodology, can also lead to inconsistencies in ranking.

Within the context of a company’s overall strategy and risk tolerance, organizational and cultural factors may influence prospect selection. In particular over-emphasis on quantitative methods may not have the intended effect. A common understanding, amongst technical and commercial disciplines and decision makers, of the background to quantification is essential.

Factors which encourage the progression of stratigraphic prospects include a dedicated geoscience effort, a separate ‘growth’ portfolio of new concepts, a formal structure for progressing these and a stable organization.
Breast screening, chicken sexing and the search for oil: challenges for visual cognition
Authors: Donnelly N. , Cave K. R. , Welland M. , Menneer T.
Published: April 2008

Interpretation of images of the Earth’s subsurface is a process whereby humans perceived and categorize visual features derived from seismic data. The seismic data are presented in the form of vertical slices showing points of change in some variable being measured (e.g. acoustic impedance) and horizontal slices showing surfaces interpolated between values at a particular time or horizon across multiple vertical slices. These images are usually highly complex and their nature has been determined largely by the technical capabilities of the hardware and software of the imaging technology. Because of these constraints, we argue, images do not convey information as readily as they could. We believe that these images could be more informative if they were constructed and tailored with known properties of the human visual system. Furthermore, little or no consideration has been given to the training and selection for image interpretation vis-à-vis the fundamental psychological skills that distinguish good from poor interpreters. In this paper we argue that tailoring images to the human visual system and developing working practices that eliminate biases will improve the detection of subtle features related to hydrocarbon traps. Furthermore, establishing training procedures that enhance the visual system’s ability to detect and encode hydrocarbon traps, and creating selection procedures that select individuals with excellent visual imagery skills will also facilitate performance.
Application of a sealing surface classification for stratigraphic related traps in the UK Central North Sea
Authors: Corcoran Joel
Published: April 2008

Traps can be categorized by defining the relationship of the seals with respect to the reservoir/seal bounding surface(s). Two major subdivisions provide the foundation of the classification;
one-seal traps
are structures which possess closed contours at the reservoir/seal interface, whereas
poly-seal traps
are those where closed contours at the reservoir/seal(s) interface do not exist or are inadequate to entirely close the trap on a single sealing surface; thus implicating the requirement of one or more base and/or lateral seals. The nature (conformable, unconformable, tectonic, facies change, waste zone) and combination of the seals essential to contain the hydrocarbon pool with respect to the one-seal and poly-seal distinction allow for further subdivisions of each of these classes. This publication catalogues a variety of Lower Cretaceous, Upper Jurassic and Tertiary stratigraphic related traps (stratigraphic and combination) from the Central North Sea with respect to fourteen applicable sealing-surface classes.

The paper also provides a source for identifying and categorizing prospective stratigraphic related traps in accordance with documented field examples from the Central North Sea. In addition, the author demonstrates the scheme as a first-pass exploration tool to rank future portfolios of stratigraphically trapped prospects with respect to the trapping integrity/reliability of the sealing surface(s).
Pleistocene coralline algal build-ups (
coralligène de plateau
) and associated bioclastic deposits in the sedimentary cover of Cutro marine terrace (Calabria, southern Italy)
Authors: Nalin R. , Basso D. , Massari F.
Published: April 2008

Carbonate build-ups mainly constructed by encrusting coralline red algae are currently developing on Mediterranean soft bottoms, at depths ranging from 20 m to 160 m. They are usually referred to as ‘
coralligène de plateau
’. Few fossil examples of these bioconstructions have been described in the literature and their evolution in the context of a stratigraphic cycle has never been modelled in detail. Cutro marine terrace (Calabria, southern Italy) preserves mid-Pleistocene deposits assigned to Marine Isotope Stage (MIS) 7 or MIS 9. Extensive algal build-ups representing the deepest unit of the succession occur in the outer and central portion of the terrace, interpreted as the most distal setting from the palaeo-shoreline. Two studied sections, Vrica and Telegrafo, showed that the solid biogenic framework grew over a basal rhodolithic layer, which was stabilized by the binding activity and overgrowth of non-geniculate Corallinales (calcareous red algae). Therefore, these bioconstructions represent a rare fossil example of
coralligène de plateau
. At the Telegrafo section,
Titanoderma pustulatum
has been identified as the major rhodolith component. The build-ups are dominated by
T. pustulatum
, associated mainly with
Mesophyllum
spp. and locally with
Lithophyllum stictaeforme
. Rhodalgal bioclastic deposits are found in lateral contact with the build-ups. The two facies developed together under a hydrodynamic regime where phases of sedimentation from storm-driven currents alternated with phases of calm conditions. They were deposited during a single stratigraphic cycle beginning with the generation of a ravinement surface during the transgressive systems tract (TST) and ending with the burial of the
coralligène
by well-sorted shoreface bioclastic sands. Optimal and extensive growth of the
coralligène
took place during the highstand systems tract (HST).
Rhodolith facies evolution and burial as a response to Holocene transgression at the Pontian Islands shelf break
Authors: Basso Daniela , Morbioli Claudia , Corselli Cesare
Published: April 2008

Cool to periglacial conditions, accompanied by a sea-level drop, are thought to result in an unchanged composition and ecological meaning of the rhodalgal carbonates, which occur frequently in the present-day, current-swept areas of the Mediterranean upper shelf. Form, internal structure and species composition of rhodoliths are believd to reflect the environmental conditions present in their biotope. To test these hypotheses, the relationship between rhodolith facies and sea-level rise was investigated in four cores recovered at the Pontian Islands (Tyrrhenian Sea) shelf break. The core basal intervals have been AMS radiocarbon dated, providing uncalibrated ages ranging from 10 040 ± 50 years
bp
to 10 380 ± 50 years
bp
. All four cores show a transition from basal rhodolith-rich, biodetritic, muddy-gravelly sand to rhodolith-barren, silty sand or sandy mud, along a deepening-upward succession. A facies of coralline-coated fragments of bryozoan colonies has been identified above the rhodolith facies as the deepest coralline growth form in all cores, before the final burial. Molluscan associations and rhodolith abundance, morphology and composition are ecologically compatible with the embedding sediment and testify the transition from the late Pleistocene circalittoral coastal detritic or shelf-edge detritic assemblages at the base of cores, up to the present-day bathyal muds. In the late Pleistocene and Holocene, as at present, the Pantine shelf was characterized by a low sedimentary input under moderate current action, fostering deep coralline growth.
Lithofacies and dynamics of a cool-water carbonate seaway: mid-Tertiary, Te Kuiti Group, New Zealand
Authors: Anastas Alexis S. , Dalrymple Robert W. , James Noel P. , Nelson Campbell S.
Published: April 2008

The Waimai, Orahiri and Otorohanga limestones of the upper Eocene to lowermost Miocene Te Kuiti Group, North Island, New Zealand, provide examples of cool-water carbonate sedimentation within seaways. The limestones are dominated by grainstones and packstones, and contain abundant bryozoans, benthic foraminifers and echinoderm fragments, with only small amounts of siliciclastic material. Horizontally bedded and cross-bedded lithofacies represent sedimentation in wave-dominated and current-dominated settings, respectively; biostrome lithofacies are less abundant and tend to be associated with the current-generated deposits. The migration of dune fields and the associated biostromes generate laterally restricted cyclic alternations of lithofacies. Stratigraphic partitioning of cross-bedded and wave-dominated lithofacies demonstrate that the Te Kuiti seaway alternated between current-dominated, wave-dominated and mixed-energy conditions. Eustatically and/or tectonically produced changes in water depth had the most important influence, with current-dominated conditions prevailing when water depth was optimal to allow flow acceleration through the seaway. Wave-dominated or mixed-energy conditions prevailed when water depth was less or more than this optimum depth. Mixed-energy conditions were most prevalent in widest seaways. The controls on seaway sedimentation inferred have application to other carbonate and siliciclastic seaway successions.
The meteorite collection of the National Museum of Natural History in Paris, France
Authors: Caillet Komorowski Catherine L.V.
Published: April 2008

The French national meteorite collection of the Muséum National d’Histoire Naturelle (MNHN) represents one of the richest collections in the world in terms of its historical heritage and scientific value, particularly for samples of observed falls (512). In fact, early meteoritic research was dominated by French 18th and 19th century scientists such as René Just Haüy, Auguste Daubrée, Stanislas Meunier and Alfred Lacroix. They all contributed, along with Jean Orcel and Paul Pellas in the last 80 years, to form this exceptional collection. The fall at L’Aigle in 1803 led to the recognition of the nature of meteorites and the promotion of the science of meteoritics by Jean-Baptiste Biot. The first catalogue of the meteorite collection elaborated by Cordier in 1837 contained 43 specimens. The collection now contains about 3385 specimens representing 1343 distinct meteorites, to which can be added at least 3000 tektites and numerous specimens of impactites, casts, artificial samples and thin sections. France has the greatest number of meteorite falls by surface unit and by number of inhabitants, with 70 distinct meteorite falls recovered. The collection offers a diverse range of meteorites such as those containing rare presolar grains, the famous carbonaceous chondrite Orgueil (fall, 14 May 1864), the first martian meteorite, Chassigny (fall, 3 October 1815) and Ensisheim (fall, 7 November 1492), which is one of the two oldest observed and documented meteorites and the first meteorite to be registered in the catalogue. The MNHN collection represents a resource that is particularly appreciated by the scientific community.
A review of the non-destructive identification of diverse geomaterials in the cultural heritage using different configurations of Raman spectroscopy
Authors: Smith David C.
Published: April 2008

Non-destructive Raman microscopy (RM) applied to geomaterials in the cultural heritage is reviewed by means of explaining selected examples representative of the different kinds of geomaterials that can be characterized and of the different kinds of analytical configuration that can be employed. To explain the versatility and considerable analytical potential of RM that result from its unique combination of capabilities, the first sections summarize the theory and practice of the method and its advantages and disadvantages. The most modern configurations (mobile RM (MRM) and ultra-mobile RM; micromapping and imaging; telescopy) are described. Applications in the new age of ‘don’t move it, don’t even touch it’ archaeometry have previously been classified into 10 domains, seven of which concern geomaterials: gems; rocks; ceramics; corroded metals; coloured vitreous materials; and mineral pigments on an inorganic or organic substrate. The representative examples here include all these domains and cover the time range from Prehistoric through Egyptian, Roman, Meso-American, Medieval, Chinese, Renaissance and Mogul cultures to modern colouring of glass and a contemporaneous simulation of submarine archaeology.
Provenance and technology of Apulian Neolithic pottery
Authors: Laviano Rocco , Muntoni Italo M.
Published: April 2008

Apulia is the best-represented region in Italy as far as archaeometric analyses of Neolithic pottery are concerned. Cross-checked use of petrological (optical microscopy), mineralogical (X-ray powder diffraction) and chemical analyses (X-ray fluorescence) have been performed, in the Dipartimento Geomineralogico of Bari University, on 375 Early to Late Neolithic (from the seventh to the fourth millennium
bc
) pottery samples from the Tavoliere and Murge areas. A correlated analysis of 134 samples of the main clayey deposits of the two areas was also conducted. Generally local clays were used and, in some cases, the exploitation of a range of different local fabrics has been verified. In Middle Neolithic sites, the use of non-local clay, probably imported, has been also determined. Few finished pots were actually exchanged at an inter-site scale during the Neolithic. Preparation of raw materials has shown different choices followed by ancient potters. Clays are usually more or less refined and the use of mineral temper such as sand, quartz, calcite and grog has been found. The maximum temperature reached during firing is usually between 600–700 and 850 °C. For some Middle Neolithic fine painted pottery higher temperatures have been suggested (between 850 and 1050 °C), revealing a better firing control and the use of kilns.
The ceramic technology used in the manufacture of Iron Age pottery from Galilee
Authors: Shoval Shlomo , Beck Pirhiyah , Yadin Esther
Published: April 2008

The Iron Age ceramic technology used in the manufacture of functional pottery from Galilee was studied. Applied methods included petrography, X-ray diffraction, infrared spectroscopy and chemical analyses. The results demonstrate that the potters in biblical times had knowledge of raw materials and manufacturing technologies, enabling them to select suitable ones, according to their advantages, for the manufacture of cooking pots, storage jars and tableware vessels. The paper describes the petrography of the pottery, the composition of the ceramic matrix, the firing temperature, the tempering of the cooking pots, the processes that allow consolidation of the ceramic and the origin of the pottery. The results are placed in an archaeological context.
Chemical and mineralogical investigations of majolicas (16th–19th centuries) from Laterza, southern Italy
Authors: Dell’Aquila C. , Laviano R. , Vurro F.
Published: April 2008

Laterza (southern Italy) was the most important town for the manufacture of Apulian majolica ceramic from the 16th century until the end of the 18th century. The Laterza majolicas have previously been subjected to only preliminary analyses. This study extends the archaeometric knowledge of the Laterza productions with mineralogical, petrographical and chemical characterizations of ceramic body, glazed coating and pigments of the majolica. A number of 16th to 19th century pottery and tile fragments of majolica have been studied and compared with clay from local and surrounding deposits. Analyses were carried out by optical microscope, scanning electron microscope, energy-dispersive spectrometry, X-ray powder diffraction, X-ray fluorescence and inductively coupled plasma. A purification process of the raw material is suggested and for some fragments, doubtfully attributed to Laterza, a different place of manufacture. Slip (‘ingobbio’) was never found under the glaze. Si, Pb and Sn are confirmed as the principal elements in the tin-glazed coatings. The differences in the glaze opacity were attributed to different manufacturing techniques and not simply the quantity of tin. The orange-yellow colour is due to a Sb-Pb compound; black to Ni with a lower amount of Co, Fe and Sb; blue to Co, As, Fe and Ni; and Mn is the pigment of the violet-brown.
Obsidian localization and circulation in northwestern Patagonia (Argentina): sources and archaeological record
Authors: Bellelli C. , Pereyra F. X. , Carballido M.
Published: April 2008

The objectives of the current research are to characterize obsidian sources and lithic archaeological remains in two areas of NW Patagonia, so as to establish spatial distribution and network circulation patterns. Obsidian tools and remains were found in archaeological contexts dated back 3200 years and up to the 16th–18th centuries. Geological and artefact sample rocks were analysed by instrumental neutron activation analysis and inductively coupled plasma emission mass spectrometry. Four potential sources were detected (Sacanana, Angostura Blanca, Portada Covunco and Laguna La Larga). Obsidians in the region appear to be related to two petrotectonic associations: (1) an arc source, located in the western part of Argentina and Chile, of Plio-Pleistocene age; (2) an intraplate and back-arc source, located in the North Patagonian Massif, east of the studied area, of Miocene age. The latter, because of the higher frequency of tools and remains that appear in archaeological context, seems to be more intensively used. Some hypotheses about obsidian circulation patterns, the mobility of northern Patagonia hunter-gatherers, and landscape occupation throughout the last 3200 years are outlined based on the results obtained in this work.
Geological tools to interpret Scottish medieval carved sculpture: combined petrological and magnetic susceptibility analysis
Authors: Miller Suzanne , McGibbon Fiona M. , Caldwell David H. , Ruckley Nigel A.
Published: April 2008

Geological surveys of 172 early and late medieval sculptured stones from central and western Scotland have been undertaken to determine the provenance of the materials used. Non-destructive petrological studies (including grain size, mineralogy distribution, and textural and structural characteristics) and magnetic susceptibility measurements are used to characterize the sculptured stones and potential source material. The results indicate that for the early medieval sculpture: (1) all the sculptured stones are sandstone with the exception of one siltstone and one granite; (2) the sedimentary rocks are consistent with sources in the Lower Old Red Sandstone of the area; (3) from within the Lower Old Red Sandstone, a number of different geological units have been used. For the late medieval sculpture, the results indicate that: (1) various rock types have been used including schist, slate and sandstone; (2) non-locally derived material is used extensively in some areas, suggesting a more developed network for procurement of raw materials. The analytical techniques used also provide additional information in the art historical interpretation of a number of carved stones by identifying carved fragments from the same monument.
Identification, characterization and weathering of the stones used in medieval religious architecture in L’Aquila (Italy)
Authors: Quaresima R. , Giampaolo C. , Spernanzoni F. , Volpe R.
Published: April 2008

In the city of L’Aquila the historical and artistic significance and the density of religious buildings is notable. From the 11th to the 19th century the ornamental stones quarried in the surroundings of L’Aquila have been used for religious architecture, civil artefacts and buildings of great artistic and historical relevance. Great emphasis has been placed on the recognition of ancient quarries where these ornamental stones were carved. In this paper the petrographical, physical, mechanical and technological characteristics of the limestones and marly limestones sampled in the quarries are reported. The main characteristics will be discussed and correlated to the decay forms, with the aim of achieving a general strategic approach based on a diagnostic phase and an application phase.
Palaeoclimate analysis of Late Cretaceous angiosperm leaf floras, James Ross Island, Antarctica
Authors: Hayes Peta A. , Francis Jane E. , Cantrill David J. , Crame J. Alistair
Published: April 2008

The fossilized remains of Cretaceous angiosperm leaves are preserved within sandstones and siltstones of the Coniacian Hidden Lake Formation (Gustav Group) and the Santonian-early Campanian Santa Marta Formation (Marambio Group) in the James Ross Basin, Antarctic Peninsula region. The leaves represent the remains of vegetation that grew at approximately 65°S on an emergent volcanic arc, now represented by the Antarctic Peninsula, and were subsequently transported and buried in marine sediments in the adjacent back-arc basin. Some of the angiosperm leaf morphotypes show similarities to leaves of living families such as Sterculiaceae, Lauraceae, Winteraceae, Cunoniaceae and Myrtaceae. Palaeoclimate analysis based on physiognomic aspects of the leaves, such as leaf-margin analysis, indicates that the mean annual temperatures for the Hidden Lake and Santa Marta formations were 13–21 °C (mean 17 °C) and 15–23 °C (mean 19 °C), respectively. The fossil plants are indicative of warm climates without extended periods of winter temperatures below freezing and with adequate moisture for growth. This period of Cretaceous warmth in Antarctica corresponds with the Cretaceous thermal maximum, an interval of peak global warmth from the Turonian to the early Campanian.
Cretaceous and Cenozoic vegetation of Antarctica integrating the fossil wood record
Authors: Poole Imogen , Cantrill David J.
Published: April 2008

A compilation of data for Cretaceous and Cenozoic Antarctic fossil wood floras, predominantly from the James Ross Island Basin, provides a different perspective on floristic and vegetation change when compared with previous studies that have focused on leaf macrofossils or palynology. The wood record provides a filtered view of tree-forming elements within the vegetation, something that cannot be achieved from studies focusing on regional palynology or leaf floras. Four phases of vegetation development in the over-storey are recognized in the Cretaceous and Cenozoic of the Antarctic Peninsula based on the distribution and taxonomic composition of wood floras: Aptian-Albian coniferous forests; ?Cenomanian-Santonian mixed angiosperm forests; Campanian-Maastrichtian southern temperate forests; and Palaeocene-Eocene reduced diversity
Nothofagus
forests. Comparisons between the wood record and information derived from palynological and leaf floras have important implications for our understanding of the spatial composition of the vegetation. There is no doubt that climate change during the Cretaceous and Tertiary influenced the vegetational composition, but evolving palaeoenvironments in the Antarctic Peninsula region were probably of equal, if not greater, importance.
Palaeobiological significance of high-latitude Late Cretaceous vertebrate fossils from the James Ross Basin, Antarctica
Authors: Martin James E. , Crame J. Alistair
Published: April 2008

A diverse marine assemblage of vertebrate fossils has been collected in recent years under the auspices of the British Antarctic Survey from Seymour, James Ross and Vega islands east of the Antarctic Peninsula. The specimens were derived from the Late Campanian Santa Marta Formation, Early Maastrichtian Snow Hill Island Formation and the Early-Late Maastrichtian López de Bertodano Formation. Sharks, teleosts, plesiosaurs and mosasaurs are represented, but birds and sea turtles are absent from the BAS collections; neornithine birds have been previously reported from the Late Cretaceous deposits of Antarctica. Shark teeth are relatively abundant, but teleosts are seemingly under-represented. Plesiosaurs (Elasmosauridae) are more abundant and complete than mosasaurs, and juveniles of both marine reptile groups are relatively common. The marine lizards, mosasaurs, are taxonomically diverse as elsewhere in the world, but with relatively few individuals compared to the plesiosaurs, which are taxonomically limited. A converse relationship normally occurs at other lower latitude Late Cretaceous localities. Some of these abundances and appearances may be due to collection bias, particularly due to difficult collecting conditions and weathering, but certain distributions may be the result of high latitudes.
Stratigraphy, correlations and palaeogeography of Palaeozoic terranes of Bulgaria and NW Turkey: a review of recent data
Authors: Yanev S. , Göncüoğlu M. C. , Gedik I. , Lakova I. , Boncheva I. , Sachanski V. , Okuyucu C. , Özgül N. , Timur E. , Maliakov Y. , Saydam G.
Published: April 2008

Within the Alpine tectonic units SE of the European Variscan Orogenic Belt in Bulgaria and NW Turkey several crustal blocks are identified. Although their contact relations with surrounding units are obscured by Alpine events, the differences in the succession of events, stratigraphy, sedimentology and palaeobiogeographical distribution within them permits recognition of the Moesian, Balkan, Istanbul and Zonguldak Terranes. The Moesian terrane corresponds to the pre-Variscan Palaeozoic and Neoproterozoic rocks of the Moesian microplate in north Bulgaria and south Romania. The Balkan Terrane in Bulgaria incorporates Neoproteozoic and Palaeozoic sequences in the Western Balkanides (part of the Carpathian-Balkan orogen) and another three allochthonous units (Kraishte, Central Balkanides and Strandzhides). In NW Anatolia in Turkey, the Caledonian basement and Ordovician to Carboniferous sedimentary succession are divided into the Istanbul Terrane and the Zonguldak Terrane. With the exception of the Moesian Terrane in the Bulgarian area, they all comprise a Cadomian basement with relicts of oceanic lithosphere, volcanic arc and a continental crust of unknown affinity. Based on characteristic features within their Palaeozoic successions, there terranes are correlated with the main terrane assemblages in Central and Eastern Europe. It is suggested that they all are of peri-Gondwanan origin but behaved independently while drifting towards Laurussia. During the Early Devonian the Zonguldak Terrane docked to Baltica, whereas the others were still at similar palaeolatitudes to the Central European terranes (e.g. Saxo-Thuringian). This was followed by the successive accretion of the Moesian Terrane to Laurussia along the Rhenohercynian suture at the end of Devonian-Early Carboniferous and of the Balkan and Istanbul Terranes the Early and Late Carboniferous.
Evolution of Early Mesozoic back-arc basins in the Black Sea-Caucasus segment of a Tethyan active margin
Authors: Kazmin V. G. , Tikhonova N. F.
Published: April 2008

Six new reconstructions illustrate the evolution of back-arc basins in the Black Sea-Caucasus region from the Mid-Triassic to the end of the Mid-Jurassic. The
c.
2000 km long Tauric (Küre) basin opened in the Late Permian-Early Triassic as the Pontides-Transcaucasus and Rhodope microcontinents rifted from the Eurasian margin. The oceanic floor of the Tauric basin in the Mid-Triassic was at least 300 km wide. In the east the basin closed near the present-day Caspian Sea and to the west of the West Crimea transform it split into two branches to the south and north of the Moesian platform. The Tauric basin was partly inverted in the Carnian, when several Gondwanian terranes (Iran, South Armenia) collided with the Palaeotethyan subduction zone. Following the initiation of a new subduction zone, the back-arc extension resumed in the Norian-Early Jurassic. Opening of the Izmir-Ankara-Sevan back-arc basin commenced south of the Pontides-Transcaucasus. Simultaneously, rifting began in the Greater Caucasus and continued until the Early Pliensbachian. This was followed by the continental break-up in the Late Pliensbachian-Toarcian. A narrow (100–150 km) strip of oceanic crust had formed by the beginning of the Aalenian. In the Late Aalenian a southward-migrating subduction zone at the southern margin of the Izmir-Ankara-Sevan basin had reached the central part of Neo-Tethys and presumably collided with a mid-oceanic ridge. Subduction was blocked and Africa-Eurasia convergence was compensated by inversion in the Tauric and Greater Caucasus basins. The basins were closed by the end of the Bathonian.
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

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

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

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.