bluuebunny/crossref_metadata_2025 huggingface dataset:
Earthquake swarm in Steigen, northern Norway: an unusual example of intraplate seismicity
Authors: Atakan Kuvvet , Lindholm Conrad D. , Havskov Jens
Published: July 2007

On the first of January 1992, unusual earthquake activity started in Steigen, northern Norway. By 31 December, 1992, a total of 207 events had been recorded in several pulses. Among these, several events with magnitudes larger than 3.0 (Mc) were also felt by the people. The epicentral distribution of these events seems to suggest that they all are concentrated in a small region (approximately 10 km in diameter) in the Brennvika Bay (67.8°N, 14.9°E), between Leinesfjorden in the north and Nordfolda in the south. The distribution of events in time is characteristic of a swarm in which no dear evidence of a mainshock–aftershock sequence was observed. Macroseismic intensity surveys as well as synthetic modelling indicate shallow focal depths in the range 5–8 km. Based on a composite focal mechanism, indicating an oblique‐slip fault striking NE with a normal component dipping NW, combined with an observed NE trend in the epicentres and the focal depths, these events correlate with a previously proposed fault zone along Nordfolda. The NE trend has been dominant in the area throughout geological time, starting from the Caledonian Orogeny to the post‐Caledonian basin developments, as well as the post‐glacial and neotectonic structural features. At present, the deep‐seated structural anomaly underneath the Lofoten Ridge seems to be the major factor controlling the structural trends in the area. The activity along the Nordfolda fault zone could be related to this large‐scale structure, although the causes of the stresses that would create the seismic activity are not very clear, as there are several possible stress‐generating mechanisms involved, such as post‐glacial uplift of the land masses, the ‘ridge‐push’ effect from Mohn's Ridge, and vertical stresses generated by the sediment loading in the adjacent basins.
Groundwater contamination risk assessment: initial methodology for highly developed areas. Case study in the Province of Milan (Italy)
Authors: Bonomi Tullia , Cavallin Angelo , Cerutti Paolo , Rotondaro Giuseppe
Published: July 2007

Maps of factors contributing to groundwater contamination risk have been produced for a sector of the province of Milan to support decision‐making in land planning and management.

Risk assessment has considered factors related to: natural vulnerability, hazard due to human activities and costs resulting from pollution. In order to evaluate existing hazard, a specific census was carried out over the area and industrial, agricultural and quarrying activities were mapped. Industrial activities were first divided into 4 groups according to national waste type regulation.

The number of data and the density of mapped factors necessitated the use of a land information system for data storage and management and map design.
The youngest big impact on Earth deduced from geological and historical evidence
Authors: Kristan‐Tollmann Edith , Tollmann Alexander
Published: July 2007

The comparison of events that followed the great impact at the Cretaceous/Tertiary boundary with those contained within the Flood myths suggests an analogous cosmic cause. This paper proposes that there is geological evidence to support this thesis which is also indicated by a careful analysis of the natural phenomena described in Flood traditions. The time, the sites, the cause, the detailed course of the events and the consequences of this catastrophe can hope to be reconstructed.
Drainage evolution in south and east England during the Pleistocene
Authors: Gibbard P.L , Allen LG.
Published: July 2007

Two major river systems operated in southern and eastern England throughout the Pleistocene: the river Thames and the Solent river. Both rivers are axial streams of comparable size draining major basinal structures comprising similar Tertiary and Mesozoic rocks. Although the modem Thames flows broadly W‐E in the London Basin, upstream of Reading it flows from the north to drain the south Midlands. It was diverted to its present course through London by glaciation in the Anglian (Elsterian) before which it flowed across East Anglia into the southem North Sea. The Solent river no longer exists since most of its course was drowned by eustatic sea‐level rise during the Flandrian Stage (Holocene). Previously, it flowed eastwards across SE Dorset and S Hampshire as an extension of the modem river Frome in the Hampshire Basin. During periods of low sea‐level (cold stages) it was a tributary of the ‘Channel River’. Fluvial aggradations provide evidence of the former courses of these substantial rivers and their tributaries. The facies and sedimentary structures indicate that the bulk of the deposits in both systems accumulated in braided river environments under periglacial climates. Fossiliferous sediments provide biostratigraphical frameworks. During temperate periods the rivers adopted singlethread courses. Evolution of both rivers reflect their responses to climatic change, local geological structure and long‐term tectonic activity. Both rivers are undoubtedly of considerable antiquity, their records potentially extend from the Early Pleistocene or Late Pliocene, but they may have originated in the early Tertiary.
The Morphometric Synthesis for landmarks and edge‐elements in images
Authors: Bookstein Fred L.
Published: July 2007

Over the last decade, techniques from mathematical statistics, multivariate biometrics, non‐Euclidean geometry, and computer graphics have been combined in a coherent new system of tools for the biometric analysis oflandmarks, or labelled points, along with the biological images in which they are seen. Multivariate analyses of samples for all the usual scientific purposes ‐ description of mean shapes, of shape variation, and of the covariation of shape with size, group, or other causes or effects ‐ may be carried out very effectively in the tangent space to David Kendall'sshape spaceat the Procrustes average shape. For biometric interpretation of such analyses, we need a basis for the tangent space that is Procrustes‐orthonormal, and we need graphics for visualizing mean shape differences and other segments and vectors there; both of these needs are managed by the thin‐plate spline. The spline also links the biometrics of landmarks to deformation analysis of curves in the images from which the landmarks originally arose. This article reviews the principal tools of this synthesis in a typical study design involving landmarks and edge information from a microfossil.
Evolution of orthogonal sets of coeval extension joints
Authors: Caputo Riccardo
Published: July 2007

The formation of two orthogonal sets of extension joints either crossing or abutting each other is a typical product of brittle deformation. Such systems of joints, with the two joint sets being geologically coeval, have been called a fracture grid‐lock. The two sets are of common genesis and thus a unique remote stress field can be inferred. This interpretation causes some perplexity if the two joint sets are purely extension fractures and formed perpendicular to the least principal stress. In the present paper a conceptual model to explain the origin and the evolution of such systems is proposed. In a volume of rock undergoing a tensional and uniform remote stress state, caused for example by a tectonic regime, two horizontal and negative (i.e. tensional) stress rates are assumed to exist. When the tensile strength of the rock is locally reached, failure occurs perpendicular to the least principal stress. Then, that direction locally experiences a positive stress drop due to the stress release. For this reason, the stress field, retaining the same principal directions, is locally distorted by a swap between the σ3 and the σ2 components in a volume of rock surrounding the fracture. As a consequence of the persisting remote stress rates, when elastic failure conditions are newly accumulated, a second fracture forms and propagates perpendicular to the previous one. Repeated failure events, stress‐drops and stress swaps eventually generate a fracture grid‐lock. The whole process is also described with a simplified analytical model by applying elasticity theory.
TEM observations of several spinel‐garnet assemblies: toward the rheology of the transition zone
Authors: Ingrin Jannick , Madon Michel
Published: July 2007

In order to better identify the mineral phase which controls the rheology of the transition zone (between 410 and 660 km depth) transmission electron microscopy observations were made on several coexisting spinel‐garnet assemblies: alkremite xenolith; pyrope‐rich – MgO:1.1Al2O3 spinel assembly deformed at 1173K, 800 MPa in a Griggs apparatus; (Mg,Fe)3(Al,Mg,Si)2Si3O12 majorite – (Mg,Fe)2SiO4 spinel assembly synthesized in a laser heated diamond anvil cell. It was found that garnet crystals systematically remain undeformed while spinel crystals are plastically deformed. These results are in accord with the assumption that the rheology of majorite is stronger than the rheology of spinel, in the conditions of the transition zone.
Magnetic properties of Pleistocene sediments from the Mediterranean sea: a correlation with the palaeoclimatic record
Authors: Lanci L. , Lowrie W. , Wezel F.C.
Published: July 2007

The magnetic properties of the late Quaternary hemipelagic sediment from piston core BS77‐15 taken in the Tyrrhenian Sea were investigated and the results compared with palaeoclimatic records. The magnetic mineralogy of the sediment was studied and the magnetic carriers were identified by their spectra of coercivity and unblocking temperature. Investigations of rock magnetic parameters such as the Natural Remanent Magnetization (NRM), the low‐field magnetic susceptibility χ, the frequency‐dependent susceptibility χfd, the acquisition of Anhysteretic Magnetization (ARM) and Isothermal Magnetization (IRM) and the Median Destructive Field (MDF) have established the downcore variations in terms of magnetic mineralogy, grain size and coercivity in the sediments. The rock magnetic parameters were compared with an alternative climatic record from the same core based on the faunal association of planktonic foraminifera. A significant correlation was found between faunal climatic record and χfd. Together with the magnetic properties of the sediment this suggests that a palaeoclimatic signal is recorded by a fine‐grained low‐coercivity fraction of the magnetic minerals.
Late Oligocene‐Miocene sedimentary evolution of the critical Alps/Apennines junction: the Monferrato area. Northwestern Italy
Authors: Clari P. , Pierre F. Dela , Novaretti A. , Timpanelli M.
Published: July 2007

The Monferrato is a key area of the Alps‐Apennine junction. It consists of a Tertiary succession, resting on Apennine‐related units, in turn overridden by the Alpine basement. The superficial expression of this crustal discontinuity is the Rio Freddo deformation zone, separating the Alpine‐related Torino hill domain from the Monferrato. Stratigraphic analyses allow the recognition of different fault‐bounded Oligo‐Miocene successions, interpreted as tectonostratigraphic units. Some of these corresponded to high‐standing blocks, others to subsiding basins. The facies distribution reflects a transpressional tectonic regime. In this general framework of wrench tectonics, sedimentation was influenced by palaeoceanographic factors during the early and latest Burdigalian, while tectonics played the dominant role during the Aquitanian and the late Burdigalian. The uniform extent and the unconformable basal boundary of the Langhian deposits suggest that the different tectonostratigraphic units presently composing the Monferrato area were in place by Langhian times.
Tectonic history of the submerged Maghrebian Chain from the Southern Tyrrhenian Sea to the Pelagian Foreland
Authors: Catalano Raimondo , Infuso Salvina , Sulli Attilio
Published: July 2007

A description is given here of the structure and tectonic evolution of the submerged NW‐SE trending Alpine belt extending from the Sardinia Channel across the Sicily Straits to the Pelagian Sea. This mainly results from re‐interpretation of the existing seismic network. In the Sicily Straits the crust comprises an allocthonous belt composed of Tertiary flysch‐type thrust slices stacked in an imbricate wedge. The wedge is composed of Mesozoic basin and platform carbonates thrusts derived by deformation of the old Sicilian continental margin. Lower Miocene to Lower Pleistocene foredeep deposits (terrigenous and clastic carbonates) filled progressively onlapping foreland basins during regional compression. In the southern Sicily offshore the deformation spanned early Miocene to early Pleistocene time. The structural evolution of the Gela foredeep shows the kinematics and timing of emplacement of the ‘Gela Thrust System’, that is believed to be the present‐day thrust front of the Sicilian accretionary wedge. In the Sicily Channel, the Plio‐Pleistocene tectono‐sedimentary history of the Lampedusa‐Linosa sector reveals evidence of middle Pliocene extensional tectonics, and indicates a rift mechanism for formation of the Sicily Channel. This event was followed by inversion tectonics and strong vertical tectonics in the late Pleistocene.
Facies and tectonic significance of two contrasting Miocene basins in south coastal Turkey
Authors: Flecker R. , Robertson A. H. F. , Poisson A. , Müller C.
Published: July 2007

Several Miocene basins are developed on a mosaic of deformed Mesozoic carbonate platforms and ophiolitic units in the Antalya region of south‐west Turkey. Two of these, the Manavgat and Köprü basins, show contrasting orientations and stratigraphies. The Manavgat basin is orientated broadly SE‐NW and contains a succession of shallow‐water reef carbonates overlain by a thick sequence of deeper‐water marls. The upper part of the succession consists of sandstones, siltstones and conglomerates, mainly deposited by gravity processes. The stratigraphy of the N‐S Köprü basin can be subdivided into a western part, which consists of coarse fan delta‐conglomerates with local patch reefs, and an eastern part with thinly bedded sandy turbidites. Tooi marks indicate north to south flow in the north of the basin, but a southeasterly direction in the area of intersection with the Manavgat basin in the south‐east. In the light of alternative regional hypotheses, it is thought that early Miocene basin initiation is related to coeval southeastward thrusting of the Mesozoic Lycian Nappes. Flexural loading is inferred to have resulted in block faulting of the foreland and this exploited pre‐existing lines of structural weakness, dating from early Mesozoic rifting. mid‐Miocene relative sea‐ level rise may relate to global eustacy, and/or regional tectonic subsidence. Finally, late Miocene renewed coarse clastic input (locally very coarse) and basin infilling reflect tectonic uplift to the north, possibly related to continuing Africa‐Eurasia convergence in the region.
Depositional processes and basin analysis of Messinian evaporites in Cyprus
Authors: Robertson A.H.F. , Eaton S. , Follows E.J. , Payne A.S.
Published: July 2007

Messinian evaporites in Cyprus resulted from the interplay of Mediterranean‐wide and eustatic sea‐level changes and local tectonics, in an inferred above‐subduction zone setting. Distinctive Tortonian‐early Messinian pre‐evaporitic facies include diatomaceous marls and microbial carbonates, overlain by a variety of gypsum facies and then by lagoonal‐lacustrine deposits and local palaeosols. Facies analysis and comparisons allow construction of a simple model, in which evaporites formed in semi‐isolated small basins not far below global eustatic sea‐level. Coarsely crystalline gypsum formedin situ along the margins of small basins and within shallow‐water lagoons (< 10 m deep); this comprised common banded‐stacked (i.e. layered) selenite, swallowtail selenite, botryoidal selenite and sugary‐bedded selenite. Fine‐grained gypsum precipitated widely and was reworked into basinal areas (< 70 m deep) by weak traction currents and low‐density turbidity currents. Shallow‐water derived selenite was also reworked basinwards by high‐density turbidity currents and debris flows. Slumps indicate tectonic instability. More detailed basin analysis can be achieved by study of individual sub‐basins. In the Polemi sub‐basin in the west, a Lower Unit (up to 60 m thick) comprises basinal gypsum, interbedded with gypsum turbidites and mass flow deposits, with slumps. This is overlain by an extensive mega‐rudite (up to 20 m thick) including up to metre‐sized clasts of marginal gypsum facies. Above, the Upper Unit (up to 70 m thick) includes shallow‐water gypsum (e.g. swallowtails), marl and minor microbial carbonates. The Pissouri sub‐basin in the south‐west exposes marginal facies of the Upper Unit, including deltaic elastics and palaeosols. The Maroni sub‐basin in the south exhibits a basinal lower gypsum unit, with laterally equivalent marginal facies (up to 50 m thick), overlain by an extensive mega‐rudite (up to 20 m thick). Finally, the Mesaoria subbasin in the north exposes relatively marginal gypsum facies in an unstable tectonic setting. Formation of the Polemi, Pissouri and Mesaoria gypsum sub‐basins relates to coeval extensional faulting and graben development. Evaporites in south Cyprus (Maroni sub‐basin) formed in elongate basins between former compressional lineaments created by localized Early Miocene thrusting. In the sub‐basins of west, south‐west and south Cyprus, large‐scale slumping of marginal gypsum facies took place towards depocentres (to form megarudite debris flows), triggered by one or several phases of extensional faulting.
Eratosthenes Seamount: collisional processes in the easternmost Mediterranean in relation to the Plio‐Quaternary uplift of southern Cyprus
Authors: Robertson A.H.F. , Kidd R.B. , Ivanov M.K. , Limonov A.F. , Woodside J. M. , Galindo‐Zaldivar J. , Nieto L.
Published: July 2007

Important new light is shed on subduction and incipient collisional processes in the Easternmost Mediterranean, notably the Plio‐Quaternary uplift of the Troodos ophiolite, from new geophysical information collected during a cruise of the R.V. Gelendzhik in July 1993, as part of the Training‐through‐Research' programme. The data collected over the Eratosthenes Seamount formed part of the site‐survey work for Leg 160 of the Ocean Drilling Program scheduled for spring 1995. The main results are that the Eratosthenes Seamount is in the process of actively subsiding, breaking‐up and being thrust, beneath both Cyprus to the north and the Levantine Basin to the south. Northwards thrusting appears to post‐date the Messinian, when evaporites accumulated around the lower flanks of a pre‐existing seamount feature. Comparison with the geology of southern Cyprus and offshore areas suggests a causative link between northward underthrusting of the Eratosthenes Seamount and late Pliocene‐mid Quaternary uplift of southern Cyprus, focused on the centre of the Troodos ophiolite.
Late Pliocene‐early Pleistocene Athalassa Formation, north central Cyprus: carbonate sand bodies in a shallow seaway between two emerging landmasses
Authors: McCallum J.E. , Robertson A.H.F.
Published: July 2007

The late Pliocene‐early Pleistocene Athalassa Formation accumulated within the Neogene Mesaoria basin of northern Cyprus, bordered by two subdued, but rising, landmasses, the Kyrenia Range to the north and the Troodos ophiolitic massif to the south. In the eastern part of the basin, the formation is dominated by cross‐stratified bioclastic‐rich sandstones interpreted as shallow‐marine, carbonate sand bodies. The sediments are described in terms of six calcarenite facies and subfacies and one sandstone fades. Palaeocurrent analysis indicates that the carbonate sand bodies formed near the southern margin of the Kyrenia landmass and then migrated southwards across a shallow‐marine platform. The driving force is believed to have been storms, generated by strong winds. Such winds during the late Pliocene‐early Quaternary were probably stronger than today in this area. Other factors influencing deposition of the formation include minor tectonic instability, and probable eustatic sea‐level changes. Study of the Athalassa Formation thus provides insights into late Pliocene‐Pleistocene palaeoenvironments in the easternmost Mediterranean.
Structural relationship between the Sea of Marmara Basin and the North Anatolian Fault Zone
Authors: Ergün Mustafa , Özel Erdeniz
Published: July 2007

The North Anatolian Fault (NAF) zone is 1500 km long, extending almost up to the Greek mainland in the west. It is a seismically active right‐lateral strike‐slip fault that accommodates the relative motion between the Turkish block and Black Sea plate. The Sea of Marmara lies along the western part of the NAF and shows evidence of subsidence. In this area pure strike‐slip motion of the fault zone changes into extensional strike‐slip movement that is responsible for the creation of the Sea of Marmara and the North Aegean basins. The northern half of the Sea of Marmara is interpreted as a large pull‐apart basin. This basin is subdivided into three smaller basins separated by strike‐slip fault segments of uplifted blocks NE‐SW. Basinal areas are covered by horizontally layered sedimentary sequences. Uplifted blocks have undergone compressional stress. All the blocks are subsiding and are undergoing vertical motions and rotations relative to one another. The uplifted blocks exhibit positive Bouguer gravity anomalies. According to gravity interpretation, there is relative crustal thinning under the Sea of Marmara. The northern side of the Sea of Marmara is marked by a distinctive deep‐rooted magnetic anomaly, which is dissected and shifted southward by strike‐slip faulting. The southern shelf areas of the Sea of Marmara are dominated by short‐wavelength magnetic anomalies of shallow origin.
Glaukǒpis ‐ an examination of the relationship between geological laws and literary creation
Authors: Luzi Mario
Published: July 2007

The present paper is an examination of the relationship between man and the great marine depths, starting from the earliest known myths up to our present‐day conception based on scientific evidence. The concept of the abyss and the horror it inspires are investigated from a philosophical and poetic point of view to emphasize the vital importance of such concept in human life.
Plate tectonics in Russia
Authors: Khain Victor E.
Published: July 2007

After a short period of propagation of Wegener's continental drift ideas in Russia in the twenties and first half of the thirties of this century, there came a much longer period (1935–1960) of fixist reaction', when vertical tectonic movements were regarded as primary and most important and horizontal ones as secondary and subsidiary. In the sixties, interest in the manifestation of horizontal movements on strike‐slip faults, overthrusts and nappe formation began to grow, and at the verge of sixties and seventies ideas of plate tectonics began to penetrate into Russia. But at the begining they met strong resistance mainly from the older generation of scientists. In spite of this, these ideas finally gained the support of the majority of Earth scientists in this country. Russian geologists and geophysicists made a significant contribution to the development of the plate tectonics theory as well as in its regional, global and theoretical aspects.
Deformational features of the Ustica volcanic island in the Southern Tyrrhenian Sea (Italy)
Authors: de Vita Sandro , Guzzetta Giuseppe , Orsi Giovanni
Published: July 2007

Macro‐ and meso‐structural analyses of the Ustica rock formations lead to an interpretation of most of the deformational features that define the structural framework of the island. A regime of sinistral transtension seems to be the best explanation for the most significant fault associations. This regime is consistent with the kinematic model for the Tyrrhenian back‐arc‐accretionary wedge system proposed by Doglioni (1991). A caldera collapse in the northern part of the island provides the major source of volcanotectonic deformation while cracks, open or filled by clastic and/or volcanic material, were formed by downslope block sliding mostly along the southern coastline. Joints in indurated surge deposits were generated by brittle deformations induced by gravity after deposition, rather than by tectonism.
Elemental and stable isotope variations in the Cretaceous–Tertiary boundary sediments from the Soča Valley, NW Slovenia
Authors: Dolenec T. , Pavšič J.
Published: July 2007

Oxygen and carbon stable isotopes and 25 elements were determined in the undisturbed K/T boundary profile of a flysch succession in the Soča Valley, Slovenia. The elemental enrichment and stable isotope anomalies are not confined strictly to the biostratigraphically defined K/T boundary. The relatively weak metal enrichment, which is probably due to the high sedimentation rate at the time of deposition of the K/T transition sequence, was found in a clayey layer and in the boundary clayey mar] 15 cm and 5 cm above the boundary, while the negative shift in δ18O and δ13C of carbonates was restricted to the basal part of the boundary clayey marl, approximately 5 cm below the boundary. It is postulated that elemental and isotopic anomalies are probably related to the supposed, so far poorly investigated impact of an extraterrestrial body in the Gorski Kotar area of Croatia.
Mitigative Anthropogeomorphology: a revived ‘plan’ for the Mediterranean Sea Basin and the Sahara
Authors: Cathcart Richard Brook
Published: July 2007

Since at least 1964 macro‐engineering has proposed solutions for Earth‐biosphere problems affecting mankind and its infrastructures. From 1929–1948 Herman Sorgel put forth his ‘Atlantropa Macroproject, which was designed to lower the Mediterranean Sea by 1 m every year by natural evaporation and to irrigate the Sahara with diverted Zaire River freshwater. The present author has slightly modernized Sorgel's gift toHomo sapiens.Construction of ‘Atlantropa’ would provide Macro‐engineering and Terraforming with a much‐needed practice run for the remaking of our Solar System's planets.
Crust and upper mantle models along the active Tyrrhenian rim
Authors: Marson I. , Panza G.F. , Suhadolc P.
Published: July 2007

The volcanic complexes from the Eolian islands to the Campania/Roman regions and Tuscany further north, rest on lithospheric sectors which overlie the Adriatic continental lithosphere sinking along the Apennine‐Maghrebian orogenic belt. Evidence for this stems from the melting, at mantle depth, of upper crustal materials as indicated by the widespread interaction of S‐type and K‐alkaline melts. The genesis of atypical magmas of the Roman Province (central‐southern Italy) appears to be the result of an important block faulting and deep lithospheric rifting of the Apennine continental margin lying parallel to and above relic sinking slabs. Intermediate and deep‐focus earthquakes indicate that the lithospheric slab is still seismically active under the Eolian‐Calabrian area and, sporadically, at the southern end of Campania. On the other hand, in the Roman/Tuscan region, it seems to be almost inactive, few earthquakes having been located with hypocentral depths not exceeding 150 km. The analysis of the spectral content of seismic sources supports the existence of two distinct zones of lithospheric shortening in correspondence of Tuscany and South Tyrrhenian sea, which are separated by a tensional region, which extends from Latium to Calabria. The existence of distinct lithospheric slabs along the Tyrrhenian rim is supported by surface wave dispersion and scattering measurements as well as P‐wave residuals, and is confirmed by the trend of long‐wavelength gravity anomalies. Bidimensional gravity models along transects in the Tyrrhenian sea and italian peninsula interpreted within the geometrical constraints imposed by the results of the interpretation of aeromagnetic, seismic and seismological data have been used to delimit the spatial distribution of the density contrasts in the upper mantle which might be due to the existence of the above‐mentioned lithospheric slabs.
Pan African layered diorite‐tonalite‐granodiorite from Sinai massif: an open system fractionation at a subduction zone
Authors: El‐Metwally Ahmed A. , Ibrahim Mohmed E.
Published: July 2007

This paper reports on the occurrence of layered Pan African dioritetonalite‐granodiorite (DTG) rocks. The layering is marked by alternation of melanocratic (M) layers (diorites and tonalites) and leucocratic (L) layers (tonalites and granodiorites). M‐samples have cumulus biotite+hornblende+relict pyroxene+plagioclase+K‐feldspars+magnetite+apatite, and have transitional calc‐alkaline and metaluminous affinities. They were derived from subduction‐related magma enriched in Rb, Ba, K and LREE and depleted in Sr and Nb. L‐samples have cumulus plagioclase+hornblende. They are enriched in Sr and depleted in Rb, Ba, K, Nb and LREE. They have calc‐alkaline and peraluminous affinites.

The formation of the rhythmic layers of DTG composition can be attributed to periodical replenishment of pulses of basic magma into a more evolved acidic magma chamber under open system conditions. Field relations, mineralogy and element concentration among the M‐ and L‐layers indicate that at the subduction zone, the ascending magma was contaminated with lower crustal materials (marginal basin metasediments) which led to LILE‐enrichment, Nb‐depletion and transition from calc‐alkaline to alkaline and from metaluminous to peraluminous affinities as well.
Detecting a sequence boundary across different tectonic domains: an example from the middle Miocene of the northern Apennines (Italy)
Authors: Amorosi A. , Colalongo M.L. , Vaiani S.C.
Published: July 2007

Sequence stratigraphic concepts can provide a powerful tool for understanding the tectono‐sedimentary evolution of areas extending across different tectonic domains. An example is provided by the upper Serravallian strata of the northern Apennines, where a sedimentological and biostratigraphic study allows a sequence boundary to be traced across the foredeep and piggy‐back basin successions. Turbidite sedimentation of predominantly alpine and subordinate apenninic provenance occurred in the apenninic foreland basin throughout the middle Miocene. Deep‐water sedimentation in the foredeep was laterally associated with deposition in shelf to slope environments in the piggy‐back basins.

In the piggy‐back basin succession, the upper Serravallian sequence boundary is a laterally extensive unconformity within homogeneous marly deposits. This unconfonnity is laterally correlative with the base of lenticular turbidite bodies. A stratigraphic lacuna affecting Zone N14 characterizes the marginal areas, where glaucony‐rich deposits assigned to Zone N15 unconformably overlie marls displaying association of Zone N13. In the depocentres, where no significant stratigraphic gap has been detected, the sequence boundary is narrowly constrained to lowermost Zone N14.

The upper Serravallian unconformity of the piggy‐back basins succession is correlative with time‐equivalent features in two distinct parts (inner basin and outer basin) of the foredeep. In the inner basin the sequence boundary separates basin margin turbidites from overlying slope hemipelagites. In a more external position (outer basin) the sequence boundary is the base of a characteristic mega turbidite of apenninic provenance (Turrito layer). In other sectors of the outer basin, where turbidite sedimentation was entirely of alpine provenance, the sequence boundary has no clear physical expression.

The observed facies distribution in the study area suggests that an important thrusting event affected the northern Apennines in the late Serravallian, resulting in submarine channel incision and nondeposition in the piggy‐back basins. Compressional activity in the foredeep was responsible for the closure of the inner basin and subsequent shifting of turbidite sedimentation in the outer basin. Slope instability led to widespread remobilization of previously deposited turbidites, triggering turbidite events of huge volume. The different characteristics of the sequence boundary in the various parts of the foredeep constitute an example of differential response of a multisourced supply system to tectonic deformation.
The Eotvos force revisited
Authors: Gasperid M. , Chierici F.
Published: July 2007

The Eotvos acceleration, too low to be the principal driving force in Wegener's theory of continental drift, where the decoupling surface was placed between crust and mantle, must be re‐evaluated in the context of Plate Tectonics, where the same surface is localized at the lithosphere‐asthenosphere boundary. In this note, taking into account the departure from spherical symmetry of the Earths internal gravitational potential, a value for the Eotvos acceleration is obtained that is one order of magnitude larger than pre‐Plate Tectonics estimates and almost two times greater than more recent results. This force was higher in the geological past because the Earths angular velocity and flattening were greater than today, and thus may be considered in the large‐scale reconstruction of continental displacements.
Active thrust tectonics in western Sicily (southern Italy): the 1968 Belice earthquake sequence
Authors: Monaco Carmelo , Mazzoli Stefano , Tortorici Luigi
Published: July 2007

The 1968 Belice earthquake sequence, characterized by six main shocks with 5 < M < 5.4, represents the strongest seismic event recorded in western Sicily in historical times. The epicentral area is located in the Belice Valley, a region lacking any topographic lineament likely to result from a fault with significant offsets of any kind. Instrumental data show that hypocentres of the major shocks are distributed along a roughly N‐dipping plane extending from about 36 km to 1 km depth. Fault plane solutions show pure thrusting mechanisms on N‐dipping, ENE‐trending planes, or oblique slip with a right‐lateral component of motion along steep WSW‐dipping planes, both as a result of approximate N‐S shortening. The observed destruction indicates that isoseismal areas are elongated in an ENE direction. Similarly, the epiccntral distribution of events with M ≥ 4 outlines a roughly elliptical ENE‐elongated area located 20 km NW of the Sciacca‐Rocca Ficuzza thrust front. This ENE‐striking structure, representing the regional morphotectonic feature closest to the epicentral area, consists of two main imbricate fan systems. In the southernmost system, Quaternary deposits (tentatively dated as 1.0–0.7 Myr old) are involved in a large ramp anticline uplifting them to a maximum altitude of 346 m. The occurrence of Holocene lacustrine piggy‐back basins on the rear of this structure also indicates late Quaternary activity of the underlying thrust. Seismological, structural and morphotectonic observations suggest that multiple ruptures might have occurred during the 1968 sequence on a blind crustal thrust ramp located beneath the epicentral area. Slip propagated southwards along the shallow ramp‐flat system characterizing the thin‐skinned foreland fold and thrust belt of southwestern Sicily, being dispersed in flexural folding processes and diffuse strain along this path.
Seismogeological effects and macroseismic fields
Authors: Tertulliani Andrea
Published: July 2007

Several seismogeological effects of earthquakes on the environment have been collected by means of the ING macroseismic procedure. The fast and easy collection of information about ground and hydrological effects constitutes a complementary instrument in assessing the effects on human structures and the environment, and, ultimately, establishing intensity values. In this paper the distribution of seismogeological effects within intensity values has been verified, using data from three moderate Italian earthquakes; the density of the same effects are then discussed in comparison with isoseismal maps.
Ancient synsedimentary structural control on thrust ramp development: an example from the Northern Apennines, Italy
Authors: Tavarnelli Enrico
Published: July 2007

The Umbria‐Marche‐Sabina foreland fold and thrust belt (Northern Apennines, Italy) provides excellent test‐cases for the hypothesis of ancient syndepositional structural features controlling thrust ramp development. The sedimentary cover, Late Triassic to Miocene in age, is made of platform and pelagic carbonates, whose deposition was controlled by significant synsedimentary extension. Normal faulting, mainly during the Jurassic and the Late Cretaceous‐Palaeogene, determined sensible lateral thickness variations within the relative sequences. By late Miocene the sedimentary cover was detached from its basement along a mainly evaporitic horizon, and was deformed by means of eastward‐verging folds and thrusts.

In order to locate the points where thrust ramps branch‐off the basal detachment, both line‐length and equal‐area techniques were used in the construction of a balanced cross‐section through three major fault‐related folds in southeastern Umbria. The nucleation of thrust ramps was controlled by the occurrence of Jurassic and Cretaceous‐Palaeogene synsedimentary normal faults. These interrupted the lateral continuity of the evaporitic unit (the Late Triassic Anidriti di Burano Fm.) at the base of the sedimentary cover, and acted as obstacles to the eastward propagation of the thrust system, giving rise to major folds which originated from tip‐line folding processes.

Therefore, the inferred relationships between ancient normal faults and late thrusts indicate that synsedimentary tectonic structures and the related lateral stratigraphic variations can be envisaged as mechanically important perturbations, which effectively control the nucleation and development of thrust ramps.
Relative sea‐level change and carbon isotopes: data from the Upper Jurassic (Oxfordian) of central and Southern Europe
Authors: Jenkyns Hugh C.
Published: July 2007

Studies on Cretaceous pelagic limestones have shown a close correspondence between putative sea‐level curves and the carbon‐isotope profile, suggesting a possible relationship between the two phenomena. Such a relationship could relate to shelf‐sea area governing the global burial rate of organic carbon which, in turn, controls the13C/12C ratio of dissolved inorganic carbon in the oceanic reservoir. In order to see whether or not this relationship might be of more general applicability, the major mid‐Oxfordian (Jurassic) transgression is documented to zonal level and appropriate carbon‐isotope data are presented. Although the applicability of ammonite zonation to the mid Oxfordian is problematic on a regional scale, a clear δ13C excursion is present in thetrunsversariurnZone, which is coincident with regional overstep and/or evidence of shoreline retreat and/or evidence of bathymetric deepening in Europe and elsewhere. The use of the carbon‐isotope curve as a proxy for shelf‐sea area or relative sea level is worthy of further exploration.
Solid bitumens: an assessment of their characteristics, genesis, and role in geological processes
Authors: Mossman David J. , Nagy Bartholomew
Published: July 2007

Familiar since antiquity, and subject in contemporary times to various characterization schemes, the exact nature of solid bitumen is not yet fully known. Bitumens have ‘random polymer‐like’ molecular structures, are mobile as highly viscous fluids or were once fluids but have since turned into solids. Solid bitumens consist mainly of large moieties, of polyclyclic aromatic hydrocarbons, occasionally with finely admixed, fine‐grained cryptocrystalline graphite. Solid bitumens are distinguished from kerogen, which is the syngenetic and generally finely dispersed particulate organic matter in sedimentary rock that virtually does not migrate following its deposition.

Occurrences of solid bitumens are relevant to petroleum exploration as well as the search for, and evaluation of, a variety of metallic mineral deposits. Genesis of bitumen is in many cases linked to the thermal and hydrothermal history of organic matter in sedimentary rock. Apparently bitumen, or more specifically organic acids generated along with bitumen during diagenesis, may alter porosity of reservoir rocks or otherwise prepare the ground for ore deposition. Bitumen is also relatively sensitive to alteration processes, some of which, such as oxidative weathering, water leaching, biodegradation (contact) metamorphism and ionizing radiation may likewise affect its nature.

Elemental composition of bitumen commonly reflects the nature of mineral deposits. Is is possible that in petroleum exploration, trace metal abundances of bitumen may eventually allow prediction of crude oil types and volumes anticipated from a given source rock? Beside transition elements, notably Ni and V, highly anomalous concentrations of U, Pt and Au occur in some solid bitumens.

During the generation of petroleum from kerogen, the trend in δ13C is toward lighter values. The opposite seems to occur when liquid petroleum is subjected to thermal cracking (and /or related processes) yielding solid bitumen enriched in 13C, and isotopically light methane. In fact, except for deasphalting and possibly some irradiation processes, the result of thermal cracking, oxidation, water leaching, inspissation (drying) and bacterial degradation of crude oil is that lower molecular weight hydrocarbons are removed leaving bitumen residues enriched in aromatic hydrocarbons, heteroatomic compounds (NSO) and 13C. Such phenomena are relevant to bitumen paragenesis in petroleum reservoir rocks, to certain Phanerozoic occurrences of multiple generations of bitumens, and to bitumens in mineral deposits.
A widespread positive δ13Ccarb anomaly at around 2.33–2.06 Ga on the Fennoscandian Shield: a paradox?
Authors: Melezhik Victor A. , Fallick Anthony E.
Published: July 2007

Carbon isotope measurements carried out on 201 carbonate samples from the early Proterozoic of the Kola Peninsula, N. Karelia and Norway yield δ13C (PDB) spanning ‐ 20.5% to + 11%. A general δ13C secular trend shows that prior to 2.33 Ga values are typically ‘normal’ marine, averaging around ‐ 3%0. Between 2.33 and 2.06 Ga, in Jatulian time, there follows a rapid excursion to positive δ13C of around + 6%. Post‐Jatulian time is characterized by δ13C of sedimentary carbonates fluctuating between ‐ 5% and +3%; also it is remarkable for the first pronounced development of diagenetic carbonates, which have δ13C between ‐ 14% and ‐ 6%. The c. 6% positive δ13C shift with a duration of about 270 Myr coincides with a maximum in the diversity and abundance of stromatolites, and with widespread development of ‘red beds’, but does not coincide with the maximum of buried Corg mass. The Fennoscandian Shield represents the largest isotoically anomalous carbonate province yet reported, and the positive δ13C excursion together with a series of major global palaeoenviromental changes seems to be more intense than the Precambrian/Cambrian transition events. However, it is still not clear what kind of mechanism this phenomenon could be attributed to. An increase of the ‘Ronov ratio’, and/or ‘Broecker ratio’ and other possible models are discussed as the target for future investigations.
Global cooling inferred from dropstones in the Cretaceous: fact or wishful thinking?
Authors: Bennett Matthew R. , Doyle Peter
Published: July 2007

Traditionally, the Cretaceous has been considered as a long period of global warmth, a ‘greenhouse’ world. This view has been challenged in recent years by several lines of evidence; palaeobotany, stable isotopes, and palaeoclimatic modelling in particular. However, although these data demonstrate that cooling is likely, the only first‐hand evidence which demonstrates the presence of substantial ice build‐up in Cretaceous high palaeolatititudes are dropstones. These outsized or exotic clasts set in a fine‐grained sediment are often interpreted as a direct result of ice rafting. The reliability of this dropstone evidence and particularly its validity is questioned in demonstrating ice age interludes within the Cretaceous greenhouse.
Late Quaternary relative sea‐level changes and the role of glaciation upon continental shelves
Authors: Plag H.‐P. , Austin W.E.N. , Belknap D.F. , Devoy R.J.N. , England J. , Josenhans H. , Peacock J.D. , Petersen K.S. , Rokoengen K. , Scourse J.D. , Smith D.E. , Wingfield R.T.R.
Published: July 2007

Sea levels of the past 20 kyr are largely determined by the response of the Earth to the last ice age. Consequently, sea‐level indicators are an important source of information about the interaction between cryosphere and hydrosphere and the solid Earth. Based on the material presented at a recent European Science Foundation conference, the present paper pin‐points some of the topics currently under discussion with respect to sea‐level evidence found on continental shelves. These topics include possible effects of erosion and changes in palaeotidal ranges on indicators of former relative sea levels as well as the problems involved in the determination of palaeo‐water depth in addition to former sea levels. More evidence is being gathered for substantial small‐scale patterns in the sea‐level changes at or nearby to the former ice margins. These patterns are not reproduced by the available geophysical models, which reconcile on first‐order level only the large‐scale pattern.
The Irish Variscides: problems, perspectives and some solutions
Authors: Keeley Martin L.
Published: July 2007

A review is presented of interpretations made to date of the Irish Variscides, and the various models of Late Palaeozoic crustal evolution. An examination is then made of the factors controlling Variscan strain in Ireland, including lithological competence, basement fabric and basement‐cover thickness. From this, the difficulties of recognizing Variscan ‘fronts’ and ‘fold belts’ are emphasized.

In order to determine whether all putative Variscan strain is indeed Variscan. in age, new time‐temperature data (vitrinite reflectance; apatite fission track populations) are discussed, along with offshore data. A case is then presented for recognizing quite distinct episodes of both Variscan and post‐Variscan heating and deformation. Some of the implications for the Variscides to the east are briefly examined, and the suitability of a regional ‘escape tectonics’ model is tested.
Metamorphic decarbonation, silicate weathering and the long‐term carbon cycle
Authors: Bickle M.J.
Published: July 2007

The seawater87Sr/86Sr curve implies a 50–100 Myr episodicity in weathering rate which requires a corresponding variation in CO2degassing from the solid earth to the atmosphere. It is proposed that this is caused by orogenesis, which both produces CO2as a result of metamorphic decarbonation reactions, and consumes extra CO2as a consequence of erosion‐enhanced weathering. Global climate on the geological time‐scale is therefore contTolled by the difference between the relatively large and variable orogenic‐moderated degassing and weathering CO2fluxes.
Magnification of undamped seismographs and the analysis of the 1906 San Francisco earthquake record obtained on the Vicentini seismograph in Zagreb (Croatia)
Authors: Herak Marijan , Allegretti Ivo , Duda Seweryn J.
Published: July 2007

A method to estimate the dynamic magnification of nonlinear seismographs is presented. The method was tested by applying it to the record of the 1906 San Francisco earthquake seismogram obtained on the Vicentini seismograph in Zagreb, in order to reconstruct the ground motion amplitudes. The magnitudes inferred from the corrected Vicentini recording of P‐ and surface waves are internally consistent (mb= 7.74, Ms= 8.48) and agree with the values published in various catalogues, within the error limits of magnitude determination for individual events. The corrected P‐waveform is compatible with a rupture slip profile exhibiting several distinct maxima along the 300 km‐long section of the San Andreas fault, in accordance with recent studies and contemporary geodetic measurements.