bluuebunny/crossref_metadata_2025 huggingface dataset:
Further research on the historical seismicity of Tunisia
Authors: Vogt Jean
Published: July 2007

A first report on the historical seismicity of Tunisia was read at the Joint EGS‐ESC‐CEC Symposium (Bologna, 1988). Subsequently, further research has revealed new information and confirmed previous doubts. Careful discussion of sources definitely throws out the famous 408 Utica earthquake and increasingly the effects of the 306–310 and 365 events seem dubious. On the other hand, several sequences (981, 1735, 1835, 1872, 1881, 1887) are better known, although the location of most epicentres still remains vague. While catalogues underestimate the frequency of events in northern as well as in southern Tunisia (where there is a zelzel legend), they continue to overestimate the intensities of modern earthquakes.
Comrie: a historical scottish earthquake swarm and its place in the history of seismology
Authors: Musson R.M.W.
Published: July 2007

Earthquake swarm activity at Comrie, Perthshire was particularly marked in the period 1839–1846. It served as a focus for early scientific interest in earthquakes in the UK, chiefly under the aegis of the British Association for the Advancement of Science. The work done included both macroseismic and instrumental investigations, and saw the first use of the inverted pendulum in seismology, as well as the first seismometer network anywhere in the world.
Known and unknown earthquakes through some European periodicals of the eighteenth century
Authors: Albini Paola , Torre Fernando Rodriguez de la
Published: July 2007

Since the eighteenth century, pioneer seismologists have used information from the periodical press to compile their lists of European earthquakes. A systematic reading of three eighteenth century periodicals –Gaceta de Madrid (1701–1750), Gazeta de Lisboa (1715–1751) and Mercure de France (1732–1763) – has been carried out in the frame of the EC project ‘Review of Historical Seismicity in Europe (RHISE)’. The retrieval of earthquake records provides data on European and Mediterranean earthquakes. Sources and records are here analysed to verify their reliability and to understand the significance of the earthquake information they supply. Special attention has been paid to earthquakes that affected Italian territory, by means of a comparison between records and space‐time, intensity parameters of the Italian seismic catalogue: this comparison shows that about 45% of the earthquakes mentioned by the periodicals are unknown in the Italian catalogue, and that 30% of them are damaging earthquakes.
Late Oligocene‐Miocene syn‐/‐late‐orogenic successions in Western and Central Mediterranean Chains from the Betic Cordillera to the Southern Apennines*
Authors: Guerrera F. , Martin‐Algarra A. , Perrone V.
Published: July 2007

The identification of syn‐ and late‐orogenic flysch deposits, extending from the Betic Cordillera to the Southern Apennines, assists in the reconstruction of the tectonic‐sedimentary evolution of the perimediterranean chains. A microplate was located between the European and African Plates during the Late Jurassic–Early Cretaceous, bordered northwards by the Piemontese Ocean and southwards by another (North Africa ‘Flysch’ Basin or Maghrebian) Ocean. The Piemontese Ocean and the northern margin of the microplate were structured from the Late Cretaceous to the Eocene to create an Eo‐alpine Chain. The southern margin of the microplate was deformed in the Aquitanian, when the internal areas of the Maghrebian Ocean were characterized by syn‐orogenic flysch deposits. This episode culminated with metamorphism (25–22 Ma) and nappe emplacement, which destroyed the former palaeogeography and created an orogenic belt (AlKaPeCa). Afterwards, a lower Burdigalian late‐orogenic cycle started in the deformed area, which as a result of the opening of the Algero‐Provençal Basin, caused the fragmentation of the AlKaPeCa, its thrusting on the ‘Flysch’ Basin and the collision with the North Africa and South Iberia Margins. These latter were folded and thrusted, the ‘Flysch’ Units pushed over the External Domain and also back‐thrusted. Langhian late‐orogenic deposits suture the new tectonic features. Finally, the whole orogen was thrust onto the foredeep during the Middle–Late Miocene.
Mantle hotspots, plumes and regional tectonics as causes of intraplate magmatism
Authors: Hawkesworth C. J. , Gallagher K.
Published: July 2007

In continental areas it is often difficult to determine the cause of intraplate magmatism. Large volumes of magma, high eruption rates, and the presence of a hotspot trace on the adjacent ocean floor, are all evidence for the presence of an anomalously hot mantle. However, in many continental magmas there are chemical variations with time which are inferred to reflect changes from asthenospheric to predominantly lithospheric source regions, or vice versa. It is argued that these chemical characteristics constrain whether magmatism was triggered by the emplacement of a mantle plume, or by lithospheric extension.
On the genesis of lava cracks in Hawaii
Authors: Scheidegger Adrian E.
Published: July 2007

The orientation structures of lava flows and lava cracks in Hawaii (Big Island) have been analysed statistically. It is shown that the lava flows do not follow epigenetic random directions, but instead follow channels that have been endogenically predesigned. Similarly, the cracks in these flows have consistent directions at 45° to the edges of the lava flows. Thus, these cracks are not simply ‘cooling joints’ but features that correspond to the edge‐crevasses in glacier‐flow: they are shearing phenomena that occur in a similar fashion in any plastic‐type flow.
238U‐series disequilibrium in the Upper Cretaceous oil shales of Israel as the primary source for the Dead Sea's 226Ra anomaly
Authors: Kronfeld J. , Minster T. , Ne'eman E.
Published: July 2007

The Dead Sea contains an anomalously high concentration of soluble radium, which is considerably in excess of its radiogenic parent uranium. Mass balance calculations demonstrated that the radium is brought to the Dead Sea by springs and shallow underground seepages. The primary source from which this radium‐excess is derived has not been identified previously. Using a combination of alpha‐spectrometry, delayed neutron activation (DNA), and gamma‐ray spectrometric analyses, it was found that the extensive oil shales within the Dead Sea watershed exhibit exceptional loss of radium. It is only the coastal hot springs and saline groundwater that have traversed the oil shales that exhibit radium‐excess. Thus, it is demonstrated that a significant portion of the radium‐excess of the Dead Sea brines is derived from the Upper Cretaceous oil shales.
Seismic response of classical monuments‐a numerical perspective developed at the Temple of Apollo in Bassae, Greece
Authors: Papastamatiou Dimitri , Psycharis Loannis
Published: July 2007

We report on the initial phase of assessing numerically the seismic vulnerability of sections of the Temple of Apollo in Bassae, in the W. Peloponnesus, Greece. The site is exposed to large subduction earthquakes and to smaller local extensional events. In this phase the only link with the seismotectonic environment is the selection of representative recorded accelerograms for numerical analysis.

The analysis confirms the highly non‐linear nature of the response of megalithic structures relying for their stability on the friction and cohesion between the constituent blocks. Intact sections of the Temple showed substantial resistance to strong ground motions due to their capacity to absorb energy with large relative movements of the building blocks that do not impair the stability of the structure. However, imperfections typical of the present condition of the monument, namely deterioration of the building stones and of the foundation material, substantially reduce the stability threshold.

Powerful numerical tools are available to assist rational schemes for the protection of ancient structures and to subject archaeological hypotheses to numerical tests. This analysis quantifies the effects of weaknesses of the structure and allows testing the effectiveness of strengthening procedures. In the archaeological context there is a strong interaction with the ongoing geodynamic processes.
Large cold anomalies in the deep mantle and mantle instability in the Cretaceous
Authors: Yuen D.A. , Čadek O.P. , Boehler R. , Moser J. , Matyska C.
Published: July 2007

Two large cold masses in the deep mantle have been delineated by using long‐wavelength seismic tomographic models in conjunction with mineralogical experimental data at high pressure. These cold anomalies are found under the western Pacific and the Americas with temperatures more than 1000 degrees below the ambient mantle temperature. These strong cold anomalies existing in the lower mantle today would suggest that there might have existed not too long ago a substantial temperature jump across a thermal boundary layer between the upper and lower mantle. Numerical simulations in an axisymmetric spherical‐shell model incorporating the two major phase transitions have shown that very large pools of cold material with temperatures of around 1500 K can be flushed down to the core–mantle boundary during this tumultuous gravitational instability. A correlation is found between the current locations of these very cold masses and regions of past subduction since the Cretaceous. Correlation analysis shows that the slab mass‐flux into the lower mantle does not behave in a steady‐state fashion. These findings may support the idea of a strong gravitational instability with origins in the transition zone, as suggested by numerical models of mantle convection.
Lithological influences on the fractal dimension of coastal morphology: the volcanic islands of Vulcano. Stromboli and Alicudi in the Southern Tyrrhenian Sea
Authors: Leonardi Sabrina , Mulargia Francesco , Rossi Pier Maria Luigi
Published: July 2007

Fractal geometry is an important concept for describing geological morphologies, providing not only a qualitative description, but also a basis for quantitative comparisons. The goal of the present study is to identify some of the geological factors which affect the fractal dimension of coastlines. In particular, a tentative classification is presented of the lithological factors influencing the coastlines of recently formed Italian volcanic islands ‐ Vulcano, Stromboli and Alicudi ‐ located in the Southern Tyrrhenian Basin.
Types of crust beneath the Ligurian Sea
Authors: Pasquale V. , Verdoya M. , Chiozzi P.
Published: July 2007

The structural setting beneath the Ligurian Sea resuJts from several tectonic events reflected in the nature of the crust. The central‐western sector, called the Ligurian basin, is part of the northwestern Mediterranean. It is a marginal basin that was generated in Oligocene‐Miocene time by subduction of the Adriatic plate beneath the European plate and by the eastward drift of the Corsica‐Sardinia block. The eastern sector belongs to the Tyrrhenian basin system and is characterized by extensional activity which since Tortonian time superimposed an earlier compressional regime. Our effort has been addressed in particular towards simplifying the complex nature of the crust of the Ligurian basin by modelling its genesis using uniform extension and sea‐floor depth variation with age. In the rift stage of the basin's evolution, the initial subsidence reaches the isostatic equilibrium level of the asthenosphere by a thinning factor of 3.15. The additional passive process, corresponding to the cooling of the lithosphere since 21 Ma, leads to a total tectonic subsidence of 3.4 km, representing the boundary of the extended continental crust. For values up to 4.1 km a transitional‐type crust is expected, whereas for higher tectonic subsidence values a typical oceanic crust should exist. After setting these constraints, the boundaries of the different crust types have been drawn based on total tectonic subsidence observations deduced from bathymetry and post‐rift sediment thickness. Although there is a general agreement with the previous reconstructions deduced from other experimental data, the oceanic realm has wider extent and more complex shape. The northernmost part of this realm shows crust of sub‐oceanic type altemating basement highs with lower subsidence values. The observed surface heat flux is consistent with the predicted geothermal held in the Alpine‐Provençal continental margin and in the oceanic domain. However, a characteristic thermal asymmetry is clearly visible astride the basin, due to the enhanced heat flux of the Corsica margin. Even if the uniform extension model accounts well at a regional level for the present basement depth, a remarkable tectonic subsidence excess has been found in the Alpine‐Provençal continental margin. This evidence agrees with the reprise in compression of the margin; the direction of the greatest principal stress is N120°E on average.
The use of correspondence analysis and principal component analysis as a tool for deducing metamorphic mineral crystallization in Mn‐rich lithologies
Authors: Jiménez‐Millán J. , Jiménez‐Espinosa R. , Velilla N. , Chica‐Olmo M.
Published: July 2007

Principal component analysis (PCA) and correspondence analysis (CA) have been used to identify several critical mineral crystallization factors during metamorphism of Mn‐rich lithologies from the Iberian Massif, Spain. Three types of variables have been considered in the system: mineralogical variables, bulk composition variables and one physical variable (oxygen fugacity). PCA was applied to the compositional variables to obtain four components, which were used as new compositional variables. These, together with the mineralogical and physical variables, were treated in the CA. The plot of the variables on the factor 1‐factor 2 plane reveals that tephroite crystallization is controlled by a compositional variable representing low values of ratio Si/(Mn+Fe) in the rocks. Moreover, it is possible to deduce from this plot the importance of high oxygen fugacity conditions for the crystallization of piemontite. The third factor shows that the crystallization of spessartine does not require very restrictive physical‐chemical conditions.
New injection experiments in non‐Newtonian fluids
Authors: Hallot E. , Auvray B. , de Bremond d'Ars J. , Martin H. , Davy Ph.
Published: July 2007

In order to identify the dominant non‐Newtonian effects which occur during the injection of a new Newtonian magma through a partially crystallized magma chamber, we have performed some preliminary analogue experiments which enable us to point out several features induced by the non‐Newtonian properties of the host fluid during injection processes. These experiments were performed in a three‐dimensional device and involve complex non‐Newtonian fluids—clay suspensions in which rheological properties such as bulk strength, yield strength and rheofluidification exponent may vary. Forced injection takes place through a slot which in the case of a Newtonian host fluid is the geometry that provides planar structures. Depending both on the density contrast and on the rheological contrast between the injected dyed water and the host fluid three kind of structures were observed: (1) permanent plumes when the injected water is lighter than the suspension exhibiting rheological properties close to Newtonian fluids; (2) pseudo‐fountains and spreading at the bottom of the tank with a destabilizing density contrast and in high yield strength/more viscous suspensions; (3) fountains with a slightly stablizing density contrast. The implications for magma chamber evolution are briefly discussed. In particular it seems that homogeneous non‐Newtonian media inhibit the formation of planar structures and partially crystallized magma may induce the spreading of the new magma at the bottom or at the top of the chamber regardless of the density contrast between the magmas.
The Roer Valley Graben earthquake of 13 April 1992 and its seismotectonic setting
Authors: Camelbeeck Thierry , van Eck Torild
Published: July 2007

A moderately sized pure, normal dip‐slip earthquake occurred in the Roer Valley Graben (RVG) near Roermond, The Netherlands on 13 April 1992 at 1h 20m UTC. This contribution presents an overview of the locations, fault‐plane solutions and magnitudes obtained for the mainshock and the aftershocks by the different scientific groups involved in their analysis. The observed maximum intensity of VII is compared with that of other earthquakes in the region to illustrate the relatively low level of damage caused by the mainshock.

Using SH and Lg waves recorded at seven local and regional broadband stations, we determine a seismic moment of 1.4 × 1017 Nm, a static stress drop of 9.7 MPa and an average displacement of 33 cm over a rupture surface of approximately 11 km2.

The seismotectonics of the region extending from the RVG to the city of Liège including the western part of the Rhenish Massif (WRM) and the eastern part of the Brabant Massif (EBM) is analysed based on the Roermond earthquake studies and data collected since 1985 by the Belgian seismic network. The geographical distribution of focal mechanism reveals four different seismotectonic regimes in this area. From stress tensor inversion we find that s̀3 coincides with the minimum horizontal stress component in the RVG, the WRM and possibly in the EBM, while in the Liège region s̀3 is approximately vertical. The minimum horizontal stress component shows a 30° rotation to the north in the WRM and the Liège region and possibly 50° in the EBM when compared with the minimum horizontal stress component in the RVG.
The Roermond earthquake of 13 April 1992, the Netherlands: geological aspects
Authors: Trifonov Vladimir G. , Klerkx Jean , Theunissen Karel
Published: July 2007

The epicentre of the Roermond earthquake is located near the western boundary fault of the Roer valley trough, one of the deepest and the most active in the Quaternary part of the Lower Rhine graben. The Late Pleistocene and Holocene activity of the trough is manifested by offsets of the main (Mindel) and the lower (Riss and Late Pleistocene) terraces along the boundary faults.

Surface fractures have been observed in an area of more than 50 km2: 2.5–3.5 km to the north of the town of Roermond, at 0.8 km to the south of the village of Herkenbosch and in the southeastern part of the village of Montfort. Three types of ruptures were differentiated: scarps up to 50 cm high along open fractures near the Maas River; open fractures (continued by scarps in some places) and open fractures with a liquefaction of the Quaternary alluvium sands. The last type is predominant. The location of the ruptures depends on the landscape and water‐table of the region. While they could be produced solely by hydraulic shock during the earthquake (increased by the wet spring season), the majority of the ruptures strike N50°W ± 10°, i.e. parallel to the main trough faults, or N55°E ± 10°, along ‘neotectonic lines’, parallel to the Maas valley and deduced from space imagery. Thus, the ruptures could be the secondary surficial effect of the earthquake, linked indirectly with the active tectonics of the region.
The Cretaceous–Tertiary boundary in southern low‐latitude regions: preliminary study in Pernambuco, northeastern Brazil
Authors: Albertão Gilberto A. , Koutsoukos Eduardo A.M. , Regali Marília P.S. , Attrep Moses , Martins Paulo P.
Published: July 2007

A preliminary integrated study of a Cretaceous‐Tertiary (K/T) boundary section in Pernambuco, northeastern Brazil, provides evidence for an extraterrestrial bolide impact in the earliest Danian. A non‐graded, nodular carbonate mudstone/wackestone bed is interpreted as a slump or a mud Flow deposit, induced by a tsunami event or by a gravity mass movement during a sea‐level lowstand, the former possibly generated by the K/T boundary Yucatán impact. This bed overlies marlstones deposited in an upper bathyal environment and marks the top of the Cretaceous. Nearly all known latest Maastrichtian planktonic foraminifera are recovered from the Cretaceous strata. Iridium shows a marked peak in a thin hemipelagic claystone layer, about 75 cm above the K/T boundary, deposited in a middle to deep neritic environment. The claystone overlies alternating beds of finegrained limestones and marlstones and a 50 cm‐thick graded bioclastic packstone, which rests upon a marly limestone breccia of the lowermost Danian. Abundant reworked Cretaceous and rare lowermost Danian microfossils (e.g. E. edita, E. eobulloides, E. fringa, G. irregularis, P. eugubina, P. cf. pseudobulloides, W. claytonensis and W. hornerstownensis) have been recovered from these strata. These lowermost Danian beds record the sudden appearance of abundant shock‐metamorphosed quartz grains, with several sets of intersecting deformation lamellae and microtektite‐like microspherules. This suggests that these deposits were formed by an additional tsunami caused by a second impact event in the earliest Danian, near or at the boundary between the Palaeocene P α and P 1a foraminiferal zones. Impact‐derived material has not been found in the uppermost Cretaceous beds.
Oceanic crust production and climate during the last 100 Myr
Authors: Kaiho Kunio , Saito Saneatsu
Published: July 2007

In order to evaluate the possible influence of oceanic crust production on climatic changes during the past 100Myr variations in total oceanic crust for this period including production at mid‐ocean ridges, oceanic plateaus, and back‐arc basins were calculated using the most recent and accurate time‐scales. The rates presented here differ from those of Larson (1991a, b) on Cenozoic fluctuations and show that (1) maximum production values occurred during the Cenomanian, Palaeocene, and late Oligocene‐early Miocene and (2) minimum values occurred in Campanian‐Maastrichtian, late Eocene, and middle Miocene. Significantly, variations of oceanic crust production correspond with variations in the δ18O of deep‐water benthic foraminifera: maximum values of oceanic crust production correspond with minimum values of δ18O, and minimum production values with maximum values of δ18O. This latter synchronism suggests that changes in land‐sea relationships and atmospheric CO2 related to major fluctuations in oceanic crust production were the main cause of mid‐Cretaceous warming and Late Cretaceous cooling, and of climatic quasi‐cycles having a periodicity of 33–38 million years over the last 100 Myr. This is the first report showing variations of ocean crust production synchronized with the Cenozoic climate changes.
Very high18o enrichment in Archean cherts from South India: implications for Archean ocean temperature
Authors: Sharma S. Das , Patil D.J. , Srinivasan R. , Gopalan K.
Published: July 2007

Stable carbon and oxygen isotopic compositions of essentially unmetamorphosed Archean (> 2.6 Gyr old) cherts and carbonates of the Dharwar Sequence of southern India, from the northernmost part of the Dharwar‐Shimoga supracrustal belt (Kalche and Nagargali), have been determined. The cherts from the Nagargali area, which preserve oolitic texture and cryptocrystalline silica, show highly enriched δ18O values ranging from 28 to 31.4%o relative to SMOW. Such values are the highest yet reported from Archean nondetrital sediments, but are similar to those of modern marine cherts. On the assumption of a seawater δ18O of 0%0, calculation of temperature based on the maximum δ18O value of 31.4%0yields a value of 40°C. This is significantly less than 70–80°C reported for the Archean oceans based on cherts and chert‐phosphate pairs. Diagenetically recrystallized microcrystalline chert‐dolomite pairs of Kalche area exhibit a range of oxygen isotopic ratios similar to those reported for Archean cherts and carbonates from other parts of the world. The temperature of diagenesis is estimated to be about 68°C.
Monitoring playa sedimentation using sequential radar images
Authors: Wadge G. , Archer D.J. , Millington A.C.
Published: July 2007

A series of ERS‐1 radar images of the Chott el Djerid playa in Tunisia obtained at intervals of 35 days demonstrates the ability to monitor geological change from space. The C‐band radar backscatter is shown from field measurements to be sensitive to changes in surface roughness at millimetric scale due to evaporative growth of halite and gypsum crystals. Backscatter increases gradually during the dry summer months and decreases rapidly in early winter as the rains begin. Episodic hydrogeological and sedimentological events including lake development, channel flow and aeolian deposition can also be detected in addition to the seasonal pattern. Multitemporal, spaceborne radar offers the prospect of being able to map the dynamics of evaporite sedimentation in continental playas.
On the interaction of geology, measurement, and statistical analysis of small‐scale permeability measurements
Authors: Jensen J.L. , Glasbey C.A. , Corbett P.W.M.
Published: July 2007

Sedimentary rocks exhibit small‐scale (mm) permeability variations which can be detected with a probe permeameter. The structure of the laminations may provide evidence about the characteristics of the measurement device. The statistical interpretation of these measurements using averages and variograms is enhanced when the geological character of the rock is taken into consideration. The three aspects of rock characterization, namely geology, measurement, and statistical analysis, are best assessed in concert. This theme is illustrated using probe data taken from sections of the Rannoch and Etive Formations, Northern North Sea.
Late Cretaceous exhumation of the Oman blueschists and eclogites: a two‐stage extensional mechanism
Authors: Michard A. , Goffé B. , Saddiqi O. , Oberhänsli R. , Wendt A.S.
Published: July 2007

The continental material of the Saih Hatat window has been affected by a Late Cretaceous, obduction‐related, HP‐LT metamorphism below the Oman ophiolite. A high‐rate exhumation process is witnessed by the Maastrichtian‐Palaeocene onlap onto the blueschist‐facies rocks. Drastic metamorphic omissions are documented between the lowest, eclogitic units and the overlying, blueschist‐facies ones. Widespread late‐metamorphic shear structures point to a top‐to‐the‐NNE detachment, in opposition to the sense of the Late Cretaceous obduction. The inversion of the shearing sense occurred under similar, low temperature conditions in both the blueschist and eclogite‐facies units. Admitting that these HP‐LT metamorphic rocks formed progressively at various depth in the subducting Arabian margin, a two‐stage extensional mechanism of exhumation is suggested: (i) early uplift of the eclogitic rocks up to the blueschists depth by ductile thinning or squeezing of a ‘blind extensional allochthon'; (ii) exhumation of the whole HP‐LT metamorphic core complex by inversion of the obduction sole‐thrust and isostatic rebound of the lower plate.
Structural evolution of the ‘41st parallel zone': Tyrrhenian Sea
Authors: Spadini Giacomo , Wezel Forese‐Carlo
Published: July 2007

The present study is based on the interpretation of more than 1300 km of 16 kJ sparker seismic profiles recorded in July 1990, during the Cruise T‐41 of the Geological Institute of Urbino. The investigated area extends along the 41st parallel in the central Tyrrhenian Sea between the northern Sardinian margin to the west and the Latium–Campanian margin to the east. This zone, situated on continental crust, marks the boundary between the northern Tyrrhenian and the southern Tyrrhenian domains.

A kinematic reconstruction is presented, based on the age‐dating of the recognized structures (i.e. normal faults, reverse faults, anticline and flower structures). The evolution of the ‘41st parallel zone’ can be described in terms of polyphase tectonics characterized by different orientations of the stress field during time. The direction of the normal fault‐trends, turned clockwise, striking NE–SW in the late Tortonian–Messinian, E–W in the early Pliocene, NNW–SSE in the late Pliocene and N–S during the Quaternary. The concurrence of compressional and strike‐slip deformations suggests oblique shear motions across the 41st parallel. The occurrence of late Pliocene–Quaternary tectonic activity in the northern Tyrrhenian Sea, locally characterized by inversion tectonics, suggests active mechanisms (intraplate compression?) superimposed on the post‐rift subsidence.
Kinematic evolution of thrust‐related structures in the Umbro‐Romagnan parautochthon (northern Apennines, Italy)
Authors: De Donatis Mauro , Mazzoli Stefano
Published: July 2007

In the internal part of the Umbro‐Marchean‐Romagnan Apennines, the foredeep clastic wedge constituting the Neogene part of the sedimentary cover is completely detached from the underlying Mesozoic–Palaeogene succession. The resulting (Umbro‐Romagnan) parautochthon consists of tectonostratigraphic units with a general geometry of broad synclinal blocks separated by narrow faulted anticlines.

Thrust‐related structures observed in the field require thrust ramp propagation to have occurred within already folded rocks; therefore, they cannot be restored using simple fault‐bend fold or fault‐propagation folding models. Evidence for a passive fold origin in the studied rocks suggests that an early detachment folding episode preceded ramp propagation. The latter was facilitated by the enhanced thickness of incompetent material in the cores of detachment anticlines, which became the preferential sites where thrust ramps cut up‐section. Depending on the trajectory of such thrust ramps, different types of fault‐related structures could develop. Hanging‐wall anticlines which give way to monoclinal structures higher up in the section are associated with listric thrust ramps, whereas hanging wall monoclines approximately parallel to the underlying fault surface are associated with straight‐trajectory ramps.

This kinematic evolution, which occurred partly during syn‐depositional compression, also accounts for the observed lithofacies distribution. The latter reflects an early differentiation of the foredeep trough into sub‐basins that are progressively younger towards the foreland. The detachment anticlines that originally bounded such sub‐basins were the site of later thrust propagation, leading to a tectonic juxtaposition of different tectonostratigraphic units consisting of broad NW‐SE elongate synclinal blocks.
Strain measurements with the borehole slotter
Authors: Becker A. , Werner D.
Published: July 2007

In the past, the doorstopper method has been used successfully for determining in situ tectonic stresses. Here an example is given about the application of the borehole slotter in the domain of tectonic stress determinations, which is an innovative strain relief technique without overcoring. Data are presented that test the reliability of the strain measurements by the borehole slotter under well‐known stress conditions, that indicate the reproducibility of borehole slotter strain data compared with those from doorstopper measurements, and that demonstrate the utility of the borehole slotter even for the determination of weak tectonic strains. In northern Switzerland the borehole slotter was used in a horizontal borehole under lithostatic loading conditions only, in a rock slope area with very heterogeneous stress conditions, and in a vertical borehole where tectonic stress should be dominant. The results show that the borehole slotter is a reliable technique, which allows precise determination of in situ strains. In addition, borehole slotter measurements are less time‐consuming and therefore less costly than most other stress‐measuring techniques—an important aspect in a future of reduced research budgets.

The borehole slotter is a strain relief technique, using a recoverable strain sensor that need not be glued to the rock surface and need not be overcored. It is quicker to use than most other stress or strain measuring techniques, especially in comparison to standard overcoring techniques (Fig. 14).

The borehole slotter supplied convincing results with respect to principal stress orientations, in good agreement with:

(i) principal stress orientations related to lithostatic stress conditions (Dittingen 2 site),

(ii) palaeostress orientations during the main stage of Jura folding only 13 to 7 Ma (Laufen 1 site),

(iii) the results of neighboring door‐stopper measurements (Dittingen 1 site).

The borehole slotter tests do not supply stress magnitudes directly. Thus, the elastic properties of the rock mass have to be determined independently. Stress ratios from borehole dotter tests in Dittingen 2 are realistic.

In conclusion, the borehole slotter is a fully developed probe to measure in situ strains in boreholes. It allows the reliable determination of a large number of data within a short time even in weakly stressed rocks. This makes the borehole slotter a powerful tool for the determination of contemporary regional tectonic stress fields.
Isotope palaeohydrology and the prediction of long‐term repository behaviour
Authors: Fontes Jean‐Charles
Published: July 2007

There are considerable, well‐recognized difficulties involved in the investigation of very low permeability rocks by conventional measurements of water potentials and spatial distribution of hydrological parameters such as permeability and effective porosity. Therefore, most studies of predictive behaviour are based on models which, when unconstrained by data, are often worse than no model at all. Geochemistry and environmental isotope geochemistry are techniques well suited for hydrological investigations of potential sites of nuclear waste isolation and for constraining predictive models.

Stable isotopes constitutive of the water molecule (2H and 18O) may give information on the origin of the water, especially 2H which is practically uninvolved in isotope exchange with rock‐forming minerals. Variations in stable isotope contents can be related to palaeohydrological and palaeoclimatic conditions whereas 3H is indicative of recent recharge.

The 13C content of dissolved carbon is related to its origin(s) and the 14C activity gives a time‐scale. However, the initial carbon isotope contents can be modified by various diagenetic effects such as precipitation/dissolution of secondary calcite and oxidation of reduced carbon. The heavy isotope content of the Total Dissolved Inorganic Carbon (TDIC) cannot be interpreted without a detailed knowledge of the carbon chemistry and of the mineralogy and isotope contents of secondary carbonates. Species of Dissolved Organic Carbon (DOC), with high molecular weights (HMW) can generally be attributed to soil derived compounds. Their 14C content may be measured by AMS (Accelerator Mass Spectrometry) thus providing an estimate of the time elapsed since recharge took place.

Chlorine‐36 is an interesting potential tool for dating old ground waters because of its long half‐life (301 kyr) and its hydrophilic behaviour. It can be also produced in situ in significant amount if the rocks are rich (some tens of ppm) in U and Th. In such cases, this time dependent build‐up provides a more systematic radiochronometer of CI‐ residence time in the rock than the decay of cosmic input 36CI, provided no Cl‐ is leached from the rock.

The isotopic composition of aqueous sulphur compounds depends on their origin and on their diagenetic evolution. The redox reactions of SO2‐4 reduction or of S2‐ oxidation are marked by strong isotope effects especially when generated by bacteria. Sulphate reduction by organic matter is a potential source of dissolved inorganic carbon and may thus interfere with 14C age interpretations.

After discussion of the possible age and origin of waters and solutes, some scenarios of evolution of local and regional palaeohydrological conditions are proposed.

Examples are given with special emphasis on detailed results from the Fennoscanian shield (Stripa project), and from northern Switzerland.
The North Aegean region: a tectonic paradox?
Authors: Pavlides Spyros , Caputo Riccardo
Published: July 2007

In the past two decades, several publications have been presented concerning the recent and active fault geometry, kinematics and geodynamics of the Aegean Region and particularly of the northern sector. Data and results are often contradictory and because of the complexity of the area most hypotheses and models should be considered carefully.

The right‐lateral movement of the North Anatolia Fault continues into some branches of the North Aegean fault system. There, strike‐slip motion along NE–SW trending faults coexists with dip‐slip E–W trending faults in the frame of an extensional regime related to N–S crustal stretching.

If we take into account the geodynamic environment of the region, several mechanical problems arise. To the east, the Aegean is compressed by the westward convergence of Anatolia, while to the south and west along the Hellenic Arc, a hemiradial compression occurs due to subduction. Although the North Anatolia–North Aegean Trough fault system resembles a restraining bend, the whole area is in fact affected by pure extension and local transtension, along NE–SW trending structures. Accordingly, the major paradox of the area and especially in the western sector (fault termination?) is the occurrence of extension where compression should regionally, or at least locally, predominate.
The Basel 1356 earthquake: which fault produced it?
Authors: Meyer Bertrand , Lacassin Robin , Brulhet Jacques , Mouroux Bernard
Published: July 2007

The 1356 Basel earthquake was the strongest event to have shaken NW Europe in the last thousand years. The peculiar location of this historical event makes it possible to relate it to normal faulting along the edges of the Rhine Graben, as well as to reverse faulting along the Jura frontal thrust or to fault reactivation within the Hercynian basement. Alternate hypotheses are discussed and their implications compared taking into account available structural data and results of the morphotectonic study performed in the epicentral area. This study combines field observations with the analysis of SPOT satellite imagery, aerial photographs, and detailed topography. It is concluded that the Basel earthquake most probably reactivated a basement fault (reverse or wrench fault) beneath the shallow‐depth aseismic detachment that underlies the Jura Mountains.
The facies properties and depositional environments of nodular limestones and red marly limestones (Ammonitico Rosso) in the Ankara Jurassic sequence, central Turkey
Authors: Varol Baki , Gökten Ergun
Published: July 2007

The nodular limestones and red marls of the Ankara region, deposited during the early to middle Jurassic, show similar palaeontological and sedimentological characteristics to those of the red nodular limestones form the Northern Alps (Adnet limestones) and from the Southern Alps (Ammonitico Rosso).

The nodular limestones appear to be hardground breccias drowned into the red marly limestones due to the instability of the bottom. The association of sponge spicules, crinoid fragments, small ostracods, benthic foraminifers, shell debris and common micrite matrix suggests a subtidal environment. The subsequent formation of red marly limestones consists of the partial dissolution of the shells; this suggests that a low sedimentation rate and/or sedimentological breaks took place during the precipitation of the ammonite‐bearing marls.

The nodular limestones (hardground breccias) and the Ammonitico Rosso‐type facies of the Ankara Jurassic succession were formed in a deeper subtidal environment and/or deeper shelf extending into the basin. The hardground layers drowned into the Ammonitico rosso were likely formed on a local carbonate shelf, that deepened increasingly through the early to middle Jurassic. Development of a local submarine clastic fan within the carbonate succession of the Ankara Jurassic basin indicates an irregular bottom topography induced by the syn‐sedimentary faults.
GPS surveys in eastern Nepal
Authors: Anzidei Marco
Published: July 2007

The Nepal region, between the Ganges plain and the Tibetan Plateau, shows the great effects of the orogenetic deformation which started between 40 and 55 Ma, following the collision between the Indian and Asiatic continental plates. Today the Himalayan chain and the Tibetan plateau are some of the best manifestations of the collision process.

Data from a geodetic network in Eastern Nepal were employed to study the motion of the crust in this recently evolved area. The data were collected by means of the Global Positioning System; this geodetic space technique can achieve a centimetric resolution in coordinate definition and baseline computation for observation sites, even those located at long distances away and it provides a powerful new tool for the comprehension of the dynamics of active tectonic regions.
QUESTION MARK
Authors: Browning Paul
Published: July 2007

Some academics (and those responsible for in‐service training within industry) may have sampled the alphabet soup that includes the acronyms: CAL, CBT, CAI and CBL. Whether these collections of letters designate Computer Aided Learning, Computer Based Teaching, Computer Aided Instruction or Computer Based Learning the initial interest on the part of the trainers (especially in the UK) is likely to have been motivated by the same question—“Will these methods allow me to teach more students, more effectively, without an increase in the level of resource?”
Observation of sections of oceanic crust and mantle cropping out on the southern wall of Kane FZ (N. Atlantic)
Authors: Auzende Jean‐Marie , Cannat Mathilde , Gente Pascal , Henriet Jean‐Pierre , Juteau Thierry , Karson Jeffrey , Lagabrielle Yves , Mével Catherine , Tivey Maurice
Published: July 2007

The objective of the 20 Nautile dives of the recent Kanaut cruise was to study the southern wall of the Kane Fracture Zone from its eastern intersection with the Mid‐Atlantic Ridge (MAR) to 5 Myr in age. The geological mapping shows four successive massifs, wrench faulted and slightly tilted. The transform‐facing walls of these massifs exhibit outcrops of fresh and serpentinized peridotites, gabbros and basalts. The entire crustal exposure is cataclased and metamorphosed to greenschist facies.
Foraminiferal changes and geochemical profiles across the Cenomanian/Turonian boundary in central and south‐east Poland
Authors: Peryt Danuta , Wyrwicka Krystyna , Orth Charles , Attrep Moses , Quintana Leonard R.
Published: July 2007

Two sections of the Upper Cenomanian and Lower Turonian in central and south‐east Poland were investigated for foraminifers, CaCO3content, carbon content insoluble in HCl (Corg) and in the carbonates (Ccarb), carbon and oxygen isotopic composition of bulk‐rock carbonates and elemental abundances. The Cenomanian/Turonian boundary interval is characterized by the appearance of more marly facies, a δ13C and δ18O stable isotope anomaly, a considerable increase in Corg content and decrease in Ccarb content and substantial changes in the foraminiferal assemblages. A major carbon stable isotope excursion with a shift of +2 (PDB) occurs in the lowermost Whiteinella archaeocretacea Zone. The late Cenomanian δ13C anomaly is associated with heavy δ18O values. The peak value of δ13C corresponds to the minima in P/B ratio and in diversity of foraminiferal assemblages. A late Cenomanian anoxic event is thought to be responsible for changes in foraminiferal assemblages. However, elemental abundance analyses do not show changes in the concentrations of trace elements. This may be explained by the long distance between studied area and a source of enrichment which was probably located in the western hemisphere.
Ijolite versus carbonatite as sources of fenitization
Authors: Morogan Viorica
Published: July 2007

Ijolite‐carbonatite complexes are ubiquitously surrounded of an aureole of metasomatically altered rocks. The process of alteration is termed fenitization and is generally caused by peralkaline fluids emanating from cooling alkaline, i.e. ijolite and carbonatite magmas. Ijolites and carbonatites normally occur together and attempts to determine the source of the fenitizing fluids may therefore lead to controversial, if not erroneous, conclusions.

Mineralogical and chemical data of fenites from Oldoinyo Lengai (Tanzania), Fen (Norway), and Alnö (Sweden) are reviewed in the present paper in order to reveal the main factors controlling the fenitization around ijolite and carbonatite. Despite the overall alkaline nature of the process, variables such as XCO2 of the fluid, activity gradients of SiO2, Al2O3 and CaO, FeO/MgO ratio, fO2 and temperature gradients may differ, producing distinctive patterns of fenitization around the two magmatic sources. The ijolitic‐type fluid has low XCO2, high activities of alkalies, SiO2 and Al2O3, and low activity of CaO. The fO2 evolves along the hm‐mt buffer conditions and the temperature falls gradually with distance from the magmatic source. The carbonatitic‐type fluid has high XCO2, high activities of alkalies and CaO, and low activities of SiO2 and Al2O3. Temperatures and fO2 are initially high, but decrease sharply with distance from the source. Moreover, the CO2‐rich fluid may complex and transport the REE.
Major river systems of central and southern Britain during the Early and Middle Pleistocene
Authors: Rose J.
Published: July 2007

Central and southern Britain was drained by two main river systems during the larger part of the Early and Middle Pleistocene: the Thames and Bytham rivers. Evidence for these rivers and their Quaternary history is represented by their sediments (the Kesgrave and Bytham Sands and Gravels, respectively), the geomorphological position of the sediments, biostratigraphy and amino acid geochronology. Evidence from the earlier parts of the Early Pleistocene (Tiglian C4b and earlier) indicates low‐energy river systems and marine conditions over much of East Anglia. For most of the Early Pleistocene (Tiglian C4c to the Cromerian Complex) the ancestral Thames was the main river with, at its maximal extent, a catchment that extended into Wales, and across East Anglia and what is now the North Sea, to join the ancestral Rhine. During this period, glaciers in the uplands of Wales and periglacial mass movement elsewhere supplied material to the catchment and it was at this time that the bulk of the sorted Quaternary ssediments of lowland Britain were deposited. The Bytham river system has no successor because the landscape now in existence has been fundamentally altered by glacial erosion. This catchment drained most of Midland England and joined the Thames in central East Anglia. Initially, the Bytham river was a tributary of the Thames, but over time it extended its catchment and at the beginning of the ‘Cromerian Complex’it became the main river of southern Britain. With the Anglian Glaciation (01 Stage 121, the Bytham river was destroyed and the Thames was diverted to its present route through London.
The Somme valley terrace system (northern France); a model of river response to Quaternary climatic variations since 800,000 bp
Authors: Antoine Pierre
Published: July 2007

Recent research on the Somme Valley terrace deposits, that began in 1987, has resulted in an integrated sequence of geological and geomorphological evidence for this area that is of particular significance for prehistoric investigations. This has been achieved using previous evidence and new results from archaeological and geological excavations. These include longitudinal profiles, cartography and detailed synthesis of sections of alluvial deposits, stratigraphy of river deposits and overlying loess sequences. The work, based on a study of the geometry of the terrace system, has resulted in the identification of ninestepped alluvial formations that occur along 70 km of the valley. Detailed study permits the integration of the various alluvial sequences. This suggests that each alluvial sequence results from sedimentation through a single glacial‐interglacial climatic cycle. This hypothesis is confirmed by investigation of soil and loess sequences of the deposits overlying the fluvial sediments. The synthesis presented provides a basis for understanding the deposition of the terrace system and an initial chronostratigraphic interpretation for the deposits.