bluuebunny/crossref_metadata_2025 huggingface dataset:
Uplift histories revealed by landforms of the Scandinavian domes
Authors: Lidmar-Bergström Karna
Published: April 2008

It has long been recognized that the Scandes (Scandinavian Mountains) consist of one dome in southern Norway and one in northern Scandinavia. In this paper a low dome is also identified in southern Sweden. The latter is associated with remains of sedimentary covers of different ages, which makes it possible to date different topographies with associated saprolites and to understand the denudational and uplift history of the dome.

The eastern flanks of the two domes in the Scandes show distinctly different topographies. The flank of the southern dome is characterized by an undulating hilly relief similar to exhumed Cretaceous surfaces in south Sweden, while the flank of the northern dome is characterized by a stepped sequence of plains with residual hills similar to Tertiary surfaces in the south. The difference in relief probably indicates different uplift histories for the two domes.
Structural and stratigraphic perspectives on the uplift and erosional history of Djebel Cherichira and Oued Grigema, a segment of the Tunisian Atlas thrust front
Authors: Baird Alastair W. , Russell Andrew J.
Published: April 2008

Djebel Cherichira, a segment of the Tunisian Atlas thrust front, was structurally uplifted by at least 1650m and possibly more than 2000m by late Tortonian and post-Messinian thrusting. After late Tortonian structural uplift and erosion, Djebel Cherichira formed a topographic high with Messinian, arid to semi-arid, debris-flow fan deposits mantling the relict topography. Oued Cherichira formed in Serravallian to early Tortonian times, prior to the growth of the thrust front, as a foreland basin fluvial system ahead of the thrust structures within the thrust belt. It maintained its antecedent drainage pattern during rapid tectonic uplift of the thrust front at Djebel Cherichira. Movement on the Kredija Strike-slip Fault records the latest tectonic event in the thrust belt. This probable Early Pliocene deformation did not displace the drainage pattern, implying that much syntectonic erosion and desert pediment formation had already occurred.

Oued Grigema, a tributary of Oued Cherichira, whilst appearing to be antecedent with respect to Djebel Cherichira, is a post-tectonic, consequent stream, where at least some of the fluvial erosion and deposition is of Holocene age. Many of the present-day processes of sedimentation and erosion in Oued Grigema are analogous to those interpreted from the Messinian strata of Djebel Cherichira.
Temporal and spatial variation in suspended sediment yields from eastern North America
Authors: Conrad Catherine T. , Saunderson Houston C.
Published: April 2008

Sediment transport data from 189 gauging stations on rivers in eastern USA and eastern Canada were used to estimate sediment yields. The length of record ranged from one to 42 years. Most stations had marked fluctuations in tonnage from one year to the next. Yields ranged spatially from 1.5 t km
−2
a
−1
to 3157 t km
−2
a
−1
when the full length of record was used. Multiquadric surfaces were generated to show time-averaged yields using five-year, ten-year, and total intervals of record. The patterns of suspended sediment yield changed when different lengths of record were used, suggesting caution when generating results from a limited record of suspended sediment data.
The significance of high planation surface in the Andes of Ecuador
Authors: Coltorti Mauro , Ollier Cliff D.
Published: April 2008

A traverse of Ecuador crosses five planated units including two main horsts which constitute the Andean Cordillera. A single surface once extended across all units, and its formation was completed by Early Pliocene times. Vertical uplift occurred mainly in the Plio-Pleistocene. Most rock structures in the Andes result from pre-planation tectonics and have no connection with mountain building. Post-planation vertical uplift created the mountains, and uplift led to gravitational spreading. The causes of stillstand and uplift are debatable but subduction and compression fail to account for the nature, the symmetry and the timing of events in the Ecuadorian Andes.
Using fallout radionuclides in investigations of contemporary overbank sedimentation on the floodplains of British rivers
Authors: Walling D. E.
Published: April 2008

Increased interest in the functioning of river floodplains has generated the need for more information on rates and patterns of contemporary overbank sedimentation. Traditional approaches to documenting rates of overbank sedimentation on floodplains face many practical difficulties, but recent advances in the application of the fallout radionuclides
137
Cs and unsupported
210
Pb afford greatly increased potential for assembling such information. The potential for using these two radionuclides to investigate contemporary overbank sedimentation is demonstrated by considering examples drawn from recent work undertaken by the author and his co-workers on the floodplains of British rivers. These examples are used to illustrate (1) establishment of recent chronologies for sediment cores collected from river floodplains, (2) documentation of the spatial pattern of overbank sedimentation rates, (3) quantification of conveyance losses associated with overbank sedimentation, and (4) investigation of changing rates of overbank sedimentation over the past 100 years.
Contribution of floodplain sequestration to the sediment budget of the Waipaoa River, New Zealand
Authors: Gomez Basil , Eden Dennis N. , Hicks D. Murray , Trustrum Noel A. , Peacock David H. , Wilmshurst Janet
Published: April 2008

Rapid vertical accretion on the Waipaoa River floodplain is conditioned by the river’s high suspended sediment load (30 000–40 000 mg l
−1
at flood stage). Cumulative sediment accumulation curves derived from three cores suggest an average (post-1850) rate of vertical accretion of
c.
60 mm a
−1
, though a 15 year lacuna in flood activity has depressed the post-1948 rate to
c.
40 mm a
−1
. Rates of aggradation during floods are several orders of magnitude larger than the time-averaged rate. Within a 44 km long reach, cross-section surveys indicate that 0.2–0.8 m of sediment was deposited between 1979 and 1990. Over this period floodplain storage accounted for 5% of the total suspended sediment load, and 16% of the suspended sediment load transported during events that exceeded bankfull stage. The Waipaoa River floodplain may be representative of floodplains bordering rivers with high suspended sediment loads, produced by rapid, episodic vertical accretion, on which overbank deposition occurs across the entire floodplain, and is complemented by channel aggradation. Such rivers are able to construct high banks. Thus channel capacities are greater and the incidence of overbank flows is less than in rivers where overbank deposition is slow relative to the rate of floodplain destruction by lateral migration. The difference between our time-averaged estimate for sequestration on the Waipaoa River floodplain and comparable estimates for actively meandering rivers, and meandering rivers with low sediment loads, reinforces the notion that there is a link between the sediment transport regime of a river and its sedimentary record. To elucidate this link it is necessary to view vertical accretion in the context of the flood events that generated it, rather than in the context of a time-averaged sediment budget.
Somerset Levels and Moors: buying off the presumptive rights of landholders to manage the land as they see fit
Authors: O’Donoghue P. J.
Published: April 2008

Designations as a Site of Special Scientific Interest (SSSI) or as an Environmentally Sensitive Area (ESA) are both intended to contribute to wetland conservation in an important farming area of Somerset. The first is a compulsory scheme and was resisted strongly on its introduction, whereas the second is based on a voluntary regime. Although the relevant SSSIs are within the Somerset Levels and Moors ESA, the two schemes are not alternatives. Both involve restrictions on agricultural practice and on farming operations, and thereby have an effect on capital and revenue values. In many, but not all, cases occupiers or owners are compensated financially. Whether such compensation is adequate from the landholder’s point of view, and whether the environmental benefits obtained as a result are equal in value to the cost of the schemes depends on how these values are measured. The future of both schemes is uncertain.
The
CM
pattern as a tool for the classification of alluvial suites and floodplains along the river continuum
Authors: Bravard Jean-Paul , Peiry Jean-Luc
Published: April 2008

The
CM
pattern is a technique used for describing textural patterns and depositional processes. Over the last 15 years in the Rhône watershed, the
CM
pattern has been intensively used to describe the actual functioning of aquatic and terrestrial environments of the river and its tributaries. Results from this research led us to propose a global
CM
pattern more adapted to floodplain environments, on which geomorphological units are mapped according to their position within the graph. In addition, data collected on a large range of fluvial environments from outwash plains to deltas confirm the mobility of the complete
CM
pattern within the graph. Each segment of the image can shift laterally or vertically in relation to the bottom turbulence of the river and/or the unit stream power. The complete
CM
pattern of river environments also provides a broad assessment of the cohesiveness of deposits in the channel and across the adjacent floodplain, and can be used to identify each river type in the continuum from torrents to deltas.
Assessing flood duration gradients and fine-scale environmental change on ancient floodplains
Authors: Wright V. P.
Published: April 2008

Existing approaches to studying ancient floodplain deposits involve integrating lithofacies and palaeopedological data to identify medium- to long-term controls on deposition. However, deciphering short-term, annual or even seasonal events such as flooding duration and hydroperiod is rarely attempted, yet it is these that control the ecology of floodplains. An approach is presented that provides insights into the patterns of flood duration in ancient floodplain successions. The ability to identify criteria indicating frequent wetting and drying is critical and this is most easily done in successions with carbonate-dominated sediments (palustrine, hard-water systems) or where Vertisol palaeosols are present. Some ancient floodplain deposits contain metre-scale units displaying drying-out trends that reflect aggradation of the floodplain surface. Evidence of hydromorphism and Fe reduction and translocation is also critical for identifying hydromorphism related to flooding, but recognizing such effects in pre-Devonian fluvial successions will be difficult because of the low levels of organic matter in soils of that interval.
Medieval iron and lead smelting works: a geophysical comparison
Authors: Vernon Robert W. , McDonnell J. Gerry , Schmidt Armin
Published: April 2008

Geophysical techniques (fluxgate gradiometry and magnetic susceptibility) have been applied to ten iron and two lead smelting sites in the North Yorkshire Moors National Park and the Pennines, respectively. These geophysical techniques, particularly magnetometry, are often regarded as having little application on such sites. Large quantities of iron slag, for example, can mask structures associated with the on-site industrial activity, and this may result in the incomplete or erroneous interpretation of the geophysical data. Geophysical surveys can, however, identify the strong magnetic anomalies associated with iron-smelting furnaces and to a lesser extent those associated with lead smelting. To provide a valid interpretation of such geophysical data it is important to understand the processes that have been conducted on iron and lead smelting sites. This paper compares and contrasts the geophysical responses produced by iron and lead smelting sites and provides examples of the structures that geophysical techniques may reveal on smelting sites.
Testing the potential of soil-stratigraphic palynology in podsols
Authors: Tipping Richard , Long Deborah , Carter Stephen , Davidson Donald , Tyler Andrew , Boag Brian
Published: April 2008

Pedological, palynological, soil-micromorphological, geochemical and soil-faunal data are presented for a weakly developed free-draining ferric podsol soil profile in which three securely dated, known-age inputs (non-native tree pollen, spheroidal carbonaceous particles,
137
Cs) have been added to the soil surface and incorporated over the last
c.
150 years, from
c.
1840
ad
. We can thus observe the mechanisms of particle incorporation over time-spans appropriate to those of pedogenic processes, and analyse the rates, depth, extent and significance of mixing processes in a soil type that has often been seen as providing secure stratigraphic contexts for subfossil pollen analysis.

Our data indicate that pollen and other particles are thoroughly and completely mixed within the L/F horizon of podsols. Mixing occurs predominantly by ingestion and bioturbation by large near-surface feeding invertebrates. Mixing is also very rapid. Transfer of pollen to lower organic horizons occurs through the liberation of pollen as large invertebrate excrement is itself ingested by enchytraeid populations, but bioturbation in these lower horizons is insufficient to move further the already-mixed pollen assemblages. The absence of earthworm populations in these acid soils means that subsequent vertical transfer to mineral horizons does not occur in any significant way. This ability of organic horizons in podsols to store pollen, the complete mixing of particles in near-surface horizons, and the prolonged time-spans over which these mixing processes can operate, indicate that resultant pollen stratigraphies are normally probably too coarse in temporal resolution to be of value in palaeoecological interpretation.
Provenancing iron ore from the Bristol Channel Orefield: the cargo of the Medieval Magor Pill Boat
Authors: Young Timothy P. , Thomas Gary R.
Published: April 2008

A boat (built
c.
1240) foundered with a cargo including iron ore, close to the settlement of
Abergwaitha
, seaward of the modern Magor Pill (Gwent). Excavation in 1995 recovered 180 kg of mixed powder and lump ores. A source within the Bristol Channel Orefield may readily be determined from the mineralogy and texture of the lump ores. Provenancing within the orefield is more problematic. Various lines of evidence constrain the likely source of the ore as Glamorgan; including textural evidence that the ore was emplaced within substantial cavernous porosity, petrological evidence that the ore was within the Carboniferous limestone, and the presence of quartz. This raises the intriguing question of why a cargo of ore was apparently travelling towards the major ore sources in the Forest of Dean. An explanation is suggested by the likely date for the cargo of 1250–1280, during the northward expansion of the de Clare Lordship of Glamorgan, into Meisgyn (including most orebodies west of the Taff Valley) in 1246, and Is Caiach (including those east of the Taff Valley) in 1267. The de Clares are known to have undertaken large-scale iron smelting in Trelech (Gwent) in the period
c.
1240–1290. It is possible that ore from the newly secured sources was shipped to Trelech for smelting during this period of insecurity.
Geoarchaeological research into the historical relics of the South Urals: problems, results, prospects
Authors: Zaykov V. V. , Bushmakin A. P. , Yuminov A. M. , Zaykova E. V. , Zdanovich G. B. , Tairov A. D. , Herrington Richard J.
Published: April 2008

A description is given here of the major geoarchaeological research undertaken in the Southern Urals region between 1991 and 1998. General petrographic characteristics of the stone material used for the manufacture of tools in the settlements of Arkaim and Alandskoe are discussed, together with their possible raw material sources. Research has indicated that Bronze Age settlements in the region used at least nine types of copper ore. One of these, the ancient mine ‘Vorovskaya Yama’, is described. Chemical analysis of metal objects from the settlements of Arkaim, Sintashta and Kuisak show that three types of copper (pure, arsenical and argentiferous) and three kinds of bronze (arsenical, stanniferous, and nickeliferous) are used for the artefacts. Buried objects show evidence of corrosion with formation of the minerals atacamite, paratacamite, nantokite, malachite, cuprite, and tenorite. The process of corrosion in the presence of organic material has been studied and malachite, azurite and sampleite have been shown to form. Microprobe analysis of gold objects from eight burial mounds shows that, in the Bronze Age, pure native gold was used to make jewellery. The use of binary artificial alloys of gold and silver is characteristic of the Early Iron Age; in the Early Middle Ages ternary artificial alloys of gold, silver and copper were used. The composition of lead wire found in the Kuisak settlement has also been determined.
The Coastal Batholith and other aspects of Andean magmatism in Peru
Authors: Cobbing E. J.
Published: April 2008

The opening of the South Atlantic ocean at 110 Ma triggered the inversion of the Casma basin and the switch from marine volcanicity to plutonism, which evolved through three distinct phases. The first was the intrusion of the Coastal Batholith which forms a well-defined linear structure over the whole coastal region and which, in the Lima segment, endured from 100 to 60 Ma, and was terminated by the formation of the ring complexes. The second was the post Incaic development of the andesitic terrestrial plateau volcanics, the Calipuy group with associated scattered plutons of tonalite and granodiorite, which extended from perhaps 50 Ma to 20 Ma, and the third was the emplacement of the high level stocks and associated ignimbrite sheets from 20 to 6 Ma. Of these the Cordillera Blanca batholith which is of trondhjemitic affinity is the most important, and it is the intrusives of this zone which are the most important economically. Many plutons within the Batholith were emplaced into the brittle crust by processes of magmatic stoping and some of the evidence for this process is presented.
Brittle behaviour of granitic magma: the example of Puente del Congosto, Iberian Massif, Spain
Authors: Fernández Carlos , Castro Antonio
Published: April 2008

The magmatic structures appearing in the Puente del Congosto granitic outcrop (central Iberian Massif) are described in this work. They are interpreted as the result of a complex interplay between viscous (Newtonian) and brittle behaviour of granitic magma, which allowed the newer magma pulses to intrude and deform older magma batches. A model of Newtonian magma intruding a linear viscoelastic host rock may be extended with some confidence to the case of magma into magma emplacement. The resulting structures combine the characteristics of dykes and diapirs. The formation of large batholiths might be initiated or entirely accomplished by this process. In order to investigate the influence of the general stress conditions characteristic of a given tectonic regime on the strength of granitic magma, an over-simplified macroscopic model considering mixed Newtonian and brittle behaviour has been developed in this work. The brittle response is simulated by the Modified Griffith criterion, so that only rough estimates of the critical differential stresses for brittle magma behaviour can be gained. The results of this model suggest that the brittle response of viscous granitic magmas is possible for any type of tectonic regime (specially under contractional tectonics). A comprehensive, physically sound model for this viscous-brittle behaviour of granitic magma is not yet available. Integrated theoretical, experimental and field-based studies are the best way to arrive at such a complete model.
Movement of melt during synchronous regional deformation and granulite-facies anatexis, an example from the Wuluma Hills, central Australia
Authors: Sawyer E. W. , Dombrowski C. , Collins W. J.
Published: April 2008

Granulite facies anatexis (
T
≈ 900 °C) in the Wuluma Hills region of the Arunta Inlier was synchronous with deformation. During D3 contractional deformation strain was partitioned into S3 shear zones, which alternate with lower strain domains containing F3 fold hinges. Subsequent D4 deformation was minor and in part extensional.

Leucosomes in the S3 shear zones are principally veins oriented parallel, or subparallel, to the pervasive S3 foliation. Leucosomes in the F3 hinge domains are more complex, and occur parallel to anisotropy due to lithological layering, the pre-existing S1/2 foliation, S3 and fold axial planes (F3 and F4). Some leucosomes (generally high Na
2
O, low K
2
O and Rb/Sr) record melt migration paths, and other sites of melt accumulation.

All the migmatites are residual and lost melt when deformation forced melt from matrix grain boundaries, through a network of small lensoid channelways to accumulation sites in fold hinges, there larger batches of magma developed. Leucosomes in accumulation sites develop a schlieric or diatexitic appearance because inflowing melt eroded the host rocks. Later increments of D3 contractional strain overpressured the accumulated granitic magma and it migrated again to other (more stable) low pressure sites through veins generally oriented parallel to S3. Magma/melt movement stopped when the solidus was reached, or the magma reached a structurally stable site (e.g. pluton).
Partial melting and
P-T-t
evolution of LP/HT metamorphic terranes: an example from the Svecofennian K-feldspar-poor leucosome migmatite belt, Southern Finland
Authors: Mouri H. , Korsman K.
Published: April 2008

The migmatites with Kfs-poor leucosomes from the Svecofennian domain of southern Finland are characterized by a suite of anastomosing leucosome veins and patches characterized by low and varying abundance of K-feldspar with or without cordierite. These leucosomes are generated by
in situ
melting reactions at different
P-T-a
H
2
O conditions. Microtextural analysis in conjunction with
thermocalc
calculations and geothermobarometry show that these rocks were metamorphosed under granulite facies conditions at 700–750°C, 4–5 kbar and
a
H
2
O = 0.4−0.7. The formation of cordierite coronas around garnet and the late crystallization of andalusite suggest that the final stage of the
P-T
history was characterized by decompression and cooling to within the andalusite stability field, estimated at 500–650°C and 3–4 kbar. U-Pb and Sm-Nd conventional analyses of monazite and garnet, respectively, from different parts of these migmatites (mesosomes and leucosomes) indicate that, within error limits, all leucosomes were formed at about 1878 Ma during a single tectonometamorphic event. Since there is no evidence of an earlier high-grade metamorphic event in this area, it is assumed that this is the approximate age of peak metamorphism and partial melting.
Seismic tomography of the Dead Sea region: thinned crust, anomalous velocities and possible magmatic diapirism
Authors: Rabinowitz Nitzan , Mart Yossi
Published: April 2008

Analysis of first arrivals of P waves from 113 earthquakes in the Dead Sea region and the calculation of a tomographic model indicates anomalous distribution of seismic velocities in the crust and the upper mantle. The seismic tomography model was applied to the lower and intermediate crust and the uppermost mantle there, at depths greater than the detection limits of seismic reflection surveys. At these depths the inversion shows two deep layers, at depths of 10–22 km and 22–32 km. The deeper layer shows average seismic velocity of 7.7 km s
−1
, and the shallower one 6.5 km s
−1
. The model suggests therefore that the Moho under the central Dead Sea is found at depth of 22 km, and the seismic velocity in the upper lithospheric mantle is anomalously low. The velocity of the layer overlying the Moho suggests a modelled layer of composite mineralogy, but high velocity anomalies were encountered in the 10–22 km layer under the boundary faults of the Dead Sea Rift, and a low velocity anomaly under the central Dead Sea is plausible. The probable interpretation of these anomalies is that the mantle under the central Dead Sea is shallow and anomalously hot, and that the lower and intermediate crust under the axial zone of the central and northern Dead Sea is also anomalously hot. Furthermore, it seems probable that magmatic diapirs ascend along the boundary faults of the rift into the intermediate crust. Structural similarity of the upper mantle and the lower crust between the Dead Sea and the northern Red Sea suggests an analogous tectonic regime for these two regions.
Extrusion dynamics of mud volcanoes on the Mediterranean Ridge accretionary complex
Authors: Kopf Achim , Behrmann Jan H.
Published: April 2008

Drilling of two submarine mud domes situated in the Olimpi field on the northern flank of the Mediterranean Ridge accretionary complex has documented episodic eruptive activity over the last 1 to >1.5 Ma. Mud extrusion is related to plate convergence between Africa and Eurasia, having caused backthrust faulting of accreted strata containing overpressured mud at depth. The domes mainly consist of mud breccia with up to 65% of polymictic clasts embedded in a clayey matrix. On the basis of modifications of Poiseuille’s and Stokes’ laws, mud extrusion rates were calculated for Milano and Napoli mud domes. Mud ascent velocities are estimated to be up to 60–300 km a
−1
, and are comparable with those of silicate magmas. Using physical property, structural and flux data of the mud breccias, and compiled data from mud domes on land, the diameter of the feeder channel and the depth of origin for the overpressured muds could be reliably estimated for the first time. Feeder channels are likely to be only a few metres wide. Gas efflux estimates constrain a source depth to
c.
1700 ± 50 m below sea floor in the Olimpi field, which is considerably shallower than estimations made from the thermal maturity of solid organic carbon in the mud breccias. The efflux data suggest that the overpressured muds were not mobilized at décollement depth, but at a shallower level within the accretionary prism. A comparison of mud ascent rates (as determined from Poiseuille flow) and the total volumes of mud extruded indicate that only a fraction of the time span constrained from biostratigraphic data (
c.
1 Ma) is needed to build up the Milano and Napoli mud domes. Durations of 12–58 ka of extrusive activity suggest mud volcanism here to have been a highly episodic phenomenon.
Holocene environmental change in the Yorkshire Ouse basin and its influence on river dynamics and sediment fluxes to the coastal zone
Authors: Macklin M. G. , Taylor M. P. , Hudson-Edwards K. A. , Howard A. J.
Published: April 2008

Geomorphological, geochemical and geochronological investigations of Holocene fluvial sedimentary sequences have been undertaken within a range of upland, piedmont and lowland valley floor reaches in the Yorkshire Ouse catchment, northern England. The aims of these studies have been to: (a) evaluate the effects of prehistoric and historic land-use change on catchment erosion and sediment delivery to river channels and floodplains; (b) establish the degree to which episodes of river erosion and sedimentation are controlled by climate-related variations in flood regime; and (c) assess the spatial heterogeneity of river response to environmental change and how this is likely to influence short- and long-term sediment storage, as well as sediment transfer to the Humber Estuary. Similar discontinuities in the Holocene alluvial record are evident at many sites in the Yorkshire Ouse catchment, though local differences in river sensitivity to externally imposed change have resulted in a complicated and often unique relationship between river behaviour and environmental change. The large proportion of particulate-borne contaminant metals (resulting predominantly from historical mining) stored in the Vale of York strongly indicates that sediment delivery from the Ouse catchment to the Humber Estuary during the Holocene may have been relatively low. This suggests that the degree of connectivity between river, estuarine and coastal transport systems, as well as spatial and temporal variations in fluvial sediment storage, are the key controls of long-term land-ocean sediment fluxes.
Modelling western North Sea palaeogeographies and tidal changes during the Holocene
Authors: Shennan I. , Lambeck K. , Flather R. , Horton B. , McArthur J. , Innes J. , Lloyd J. , Rutherford M. , Wingfield R.
Published: April 2008

Analysis of cores collected from Late Devensian (Weichselian) and Holocene sediments on the floor of the North Sea provides evidence of the transgression of freshwater environments during relative sea-level rise. Although many cores show truncated sequences, examples from the Dogger Bank, Well Bank and 5 km offshore of north Norfolk reveal transitional sequences and reliable indicators of past shoreline positions. Together with radiocarbon-dated sea-level index points collected from the Holocene sediments of the estuaries and coastal lowlands of eastern England these data enable the development and testing of models of the palaeogeographies of coastlines in the western North Sea and models of tidal range changes through the Holocene epoch. Geophysical models that incorporate ice-sheet reconstructions, earth rheology, eustasy, and glacio- and hydroisostasy provide predictions of sea-level relative to the present for the last 10 ka at 1-ka intervals. These predictions, added to a model of present-day bathymetry, produce palaeogeographic reconstructions for each time period. The palaeogeographic maps reveal the transgression of the North Sea continental shelf. Key stages include a western embayment off northeast England as early as 10 ka
bp
; the evolution of a large tidal embayment between eastern England and the Dogger Bank before 9 ka
bp
with connection to the English Channel prior to 8 ka
bp
; and Dogger Bank as an island at high tide by 7.5 ka
bp
and totally submerged by 6 ka
bp
. Analysis of core data shows that coastal and saltmarsh environments could adapt to rapid rates of sea-level rise and coastline retreat. After 6 ka
bp
the major changes in palaeogeography occurred inland of the present coast of eastern England. The palaeogeographic models provide the coastline positions and bathymetries for modelling tidal ranges at each 1-ka interval. A nested hierarchy of models, from the scale of the northeast Atlantic to the east coast of England, uses 26 tidal harmonics to reconstruct tidal regimes. Predictions consistently show tidal ranges smaller than present in the early Holocene, with only minor changes since 6 ka
bp
. Recalibration of previously available sea-level index points using the model results rather than present tidal-range parameters increases the difference between observations and predictions of relative sea-levels from the glacio-hydro-isostatic models and reinforces the need to search for better ice-sheet reconstructions.
Differential compaction of interbedded sandstone and coal
Authors: Laubach Stephen E. , Schultz-Ela Daniel D. , Tyler Roger
Published: April 2008

Cretaceous and Tertiary coal beds in the western United States typically contain subvertical opening-mode fractures (cleat). However, closely spaced normal faults abruptly substitute for opening-mode fractures in coal beneath some sandstone lenses having blunt terminations. Differential forced-fold compaction of coal beds around and beneath lens-shaped sandstone bodies accounts for such shifts in fracture style. Finite element modelling of coal deformation shows that shear stress is augmented in coal layers below abruptly tapering edges of sandstones lenses, favouring fault development, whereas under gradually tapering lenses shear stresses are not sufficiently enhanced to cause shifts in fracture style. Upper Cretaceous Mesaverde Group coal beds in southwest Wyoming have significant variations in fracture style over distances of a few to tens of metres. Because these faults have little or no porosity, the coal that contains them is likely to have low permeability compared to coal having typical (generally porous) opening-mode fractures. Thus, shifting fracture style may affect regional and local gas and water flow in coal beds.
Late Quaternary monoclinal folding induced by caldera resurgence at Ischia, Italy
Authors: Tibaldi Alessandro , Vezzoli Luigina
Published: April 2008

The main structure of the active resurgent caldera of Ischia is uncommonly well exposed. The very young age of the resurgence (<33 ka
bp
) has enabled the uppermost part of the uplifted block to be preserved, whereas the severe erosion on the steep flanks, made up of low-resistant pyroclastic deposits, has resulted in the rest of the resurgent block structure cropping out. The uppermost part is characterized by strata gently dipping at 1–5° in a general south-southeast direction. Along the southern flank of the resurgent block, the strata gradually form a complex double monocline fold with ENE-trending hinge lines. Some tens of metres below the topographic surface, the anticline part of each monocline fold gradually turns into a vertical fault. The middle limb strata are vertical to subvertical. This draping occurred with the aid of at least one main detachment horizon localized inside the pyroclastic succession. Total resurgence here is about 350 m. The opposite northern flank of the resurgent horst, which has experienced maximum uplift of the order of about 900 m, is characterized by a few vertical to subvertical normal faults with draping of strata. These data suggest that the outward-dipping strata commonly found in Quaternary resurgent calderas could represent; (i) the surface expression of forced folding induced by the piston-like uplift of a fault-bounded concealed block; or (ii) the classical doming induced by radial and vertical growth. The fault-bounded horsts sometimes recognized in old, deeply eroded, resurgent calderas could be the forcing block of non-preserved drape folds. These monocline folds could also be disrupted by upward propagation of the bounding faults after an incremental offset beyond the limit of folding of a given volcanic succession.
Stratal fold patterns adjacent to normal faults: observations from the Gulf of Mexico
Authors: Mansfield C. S. , Cartwright J. A.
Published: April 2008

This paper describes the study of a subsurface array of young growth faults from the Gulf of Mexico, using a high-resolution three-dimensional (3D) seismic data set. The seismic data have resolved all of the faults within the survey area in detail, enabling the full three-dimensional structure and displacement patterns of the faults to be accurately mapped. In this paper, special attention is paid to the magnitude and orientation of small ‘drag’ folds that occur in the wall-rock of these faults, ubiquitous throughout the data set and well resolved by the seismic data. The results indicate that in both the footwalls and the hangingwalls the folds occur with variable amplitude, and also that they are small in relation to the dimensions of the respective faults. That is, they are spatially impersistent, often exhibiting rapid changes from normal drag to reverse drag over distances as short as 100 m. Furthermore, strong discordance with the recorded patterns of throw (the vertical component of displacement) suggests that no simple apparent correlation exists with the respective displacement distributions.

By comparison with a number of field and theoretical examples, various mechanisms are discussed to explain the probable origin and variability of these folds. In general, however, evidence for the cause of the folds is limited and remains largely inconclusive. It is suggested that one potential explanation is stratal deformation in the vicinity of points of overlap and linkage between faults in the dip direction (dip linkage). In an earlier study of the fault throw distributions it is has been argued that this is the preferential mechanism by which faults in this part of the Gulf of Mexico enlarged their surface area during growth.
Effects of interlayer slip in model forced folds
Authors: Couples G. D. , Lewis H.
Published: April 2008

Forced-fold models, constructed from multiple sheets of rock layers and other materials, are deformed, under confining pressure, by the translations and rotations of a steel-block forcing assembly. The first-order response of these models is like that observed in earlier sets of models: an asymmetric fold pair develops over the uplifted edge of the rigid, primary forcing block; the layers translate into the folding area without being pushed; and bending deformation imparts spatially variable strains onto the layered package. The second-order response of the new experiments is quite different from earlier work — the new multilayered models develop temporally variable bending strains caused by the progressive development of interlayer slip on
some
of the layer-layer interfaces. The presence of the layer-parallel slip surfaces reduces the bending resistance, and it causes the resulting folds to be more localized and to have different shapes than in similar experiments where layering is less effective. In the multilayer models, faulting in the layered package is much reduced compared to similar models without multiple layering, and material strains are everywhere smaller in the layers. Layer contractions and elongations of the layering are produced in these forced-fold models as a consequence of the flexure process, without regard to farfield causative loads. The models reveal a progression of deformation consequences that is related to the mechanical effectiveness of the layering. If the understanding of process gained from these models is extended to natural folds, it becomes possible to explain both the observed differences of fold shape and some of the variations in subsidiary deformations.
Geometry of fold arrays in the Silesian-Cracovian region of southern Poland
Authors: Teper Leslaw
Published: April 2008

A zone of deformation characterized by en echelon folds extends along the northeast margin of the Upper Silesian Coal basin in southern Poland. The zone is well exposed by mining in numerous collieries where the deformation involving Upper Carboniferous strata can be observed. Folds and associated faults form a structural pattern consistent with an origin in dextral convergent wrenching on both the principal deep-seated fractures and the subsidiary faults affecting crystalline basement beneath this part of the basin. The zone is cross-cut by sublatitudinal fold belts which, according to their geometrical parameters, seem to result from alternate transcurrent shearing along west-east oriented fractures in the basement, sinistral in one case and dextral in the other. Among folds caused by the concentrated operation of a force couple whose vectors lie in the horizontal plane, there are examples of bending folds (forced folds) in each array resulting from vertical components of movement of deep-seated fault blocks. The dimensions of the folds change with depth, and the axial trend and the inclination of axial surfaces differ with distance from the basement fault trace. The length of fold segments strongly depends on axes orientation. Widely distributed evidence of interlayer slip demonstrates a variable spatial distribution of tectonic-transport direction in the sedimentary sequence. The above-mentioned features and other geometrical attributes of the fold arrays enable the dynamics of the forcing structures during Variscan tectogenesis to be determined and illustrate a hierarchical structure of the basement boundary zones. Examples from the Silesian-Cracovian region suggest that bending folds (forced folds) can sometimes originate in conditions provided by a strike-slip regime.
Complex metamorphic zonation of the Thaya dome: result of buckling and gravitational collapse of an imbricated nappe sequence
Authors: Štípská P. , Schulmann K. , Höck V.
Published: April 2008

The metamorphic isograd geometry and dome structure of the Thaya tectonic window, which emerges through the Moldanubian nappe pile at the eastern margin of the Bohemian Massif, is interpreted as a result of large-scale buckling of an imbricated nappe sequence. This large-scale mechanical instability was initiated by the blocking of passively transported hot viscous rocks to shallow crustal levels. The wavelength and shape of the buckle fold is controlled by the greatest thickness of the uppermost nappe and by the low ratio of strong orthogneiss to weak micaschists in individual nappes. The steep inclinations of the thrust surfaces and the oblique movement of the crustal multilayer minimizes the role of gravity on fold generation. Medium-scale gravitational folds originated at the end of the buckling of the nappes and are associated with the late sliding of the nappes away from the core of the anticline during late exhumation. Thermal, rheological and fold calculations are presented which document and explain the mechanism of folding of large-scale crystalline nappes.
The gravity field of the Karakoram Mountain Range and surrounding areas
Authors: Caporali A.
Published: April 2008

A ‘blank on the map’ only 60 years ago, the Karakoram Range has been explored and surveyed with greater difficulty than the Himalaya and Tibet due to its rugged terrain and extensive glaciation. In the past ten years we have succeeded in doubling the number of gravity stations. A substantial improvement in coverage and overall quality was obtained by concentrating on previously unsurveyed areas and by validating older data with more accurate measurements. Our data were merged with earlier data, converted to full Bouguer anomalies and gridded. The resulting Bouguer anomaly map defines very precisely the gravimetric low associated with the Nanga Parbat-Haramosh syntaxis, and the huge negative anomalies between the Karakoram Fault and the Main Karakoram Thrust. Large negative values are now visible also in the Ghujerab-Khunjerab areas. Correlation of the topography and Bouguer anomaly shows that a plate of flexural rigidity with
D
= 2 × 10
24
Nm fits the coherence data in the Karakoram at all but two distinct frequency ranges centred at wavelengths of 80 and 300 km. In a rheologically layered lithosphere developing a buckling instability under horizontal compression, the observed spectral features of the topography and Bouguer gravity anomalies constrain the depth of the competent layers to be in the range 13–20 km and 50–75 km respectively.
Mafic sheets from Indian plate gneisses in the Nanga Parbat syntaxis: their significance in dating crustal growth and metamorphic and deformation events
Authors: Treloar P. J. , George M. T. , Whittington A. G.
Published: April 2008

Indian plate, granulite facies, migmatitic basement gneisses exposed within the Nanga Parbat syntaxis host at least two generations of mafic sheets. In the southern part of the syntaxis, concordant sheets yield Palaeo-Proterozoic model ages of 2.2–2.6 Ga, which probably date early stages of continental growth. In the northern part of the syntaxis the sheets include a suite of discordant, silica-saturated or oversaturated sub-alkaline basalts extracted from a slightly depleted sub-continental mantle. Nd model ages and an imprecise Sm-Nd isochron yield an age of emplacement at between 1.6 and 1.8 Ga. That these dykes cross-cut granulite facies migmatitic fabrics implies that peak metamorphism in the Indian plate gneisses was, at latest, Meso-Proterozoic and not Tertiary in age. Zircon and amphibole ages published elsewhere suggest that this metamorphism was probablyc.1850 Ma in age. That the basement gneisses were refractory by the Tertiary has implications for the derivation of leucogranite sheets during the Neogene. Although the gneisses experienced a Tertiary-aged metamorphism, it was to lower temperatures than the Meso-Proterozoic metamorphism. Unless the gneisses were rehydrated during the Tertiary, the leucogranites need to have been sourced from more fertile rocks underplating the granulite facies basement complex.
Tectonics of the SW margin of the Nanga Parbat-Haramosh massif
Authors: Edwards M. A. , Kidd W. S. F. , Khan M. A. , Schneider D. A.
Published: April 2008

We present an analysis of the tectonic evolution of the southwestern portions of the Nanga Parbat massif, Pakistan Himalaya, based upon detailed mapping and structural analyses from the Bunar, Biji, Diamir, Airl, Niat and SW Rupal valleys. Mainly metasedimentary cover rocks of the Indian plate are divided into upper and lower cover. There is a marked structural thinning of the cover in the main Bunar valley from south to north, and this is attributed to a major frontal ramp in the original Main Mantle Thrust (MMT). A hitherto unmapped shear zone, the Diamir Shear Zone, is identified, that is associated with a syn-kinematically intruded belt of granitic rocks, the Jalhari Granite. The shear zone is a several kilometre thick, generally W-vergent, ductile to brittle shear zone that is associated with local overturning of the entire MMT section, typified by the Gashit Fold.
40
Ar/
39
Ar cooling ages from across the area indicate a steep cooling age gradient across the Diamir Shear Zone from >40 to <5 Ma. The Diamir Shear Zone is mechanically linked to part of the Raikhot Fault System and, together, they are seen to be a crustal-scale reverse fault that has allowed relative uplift and overthrusting of the core of Nanga Parbat.
Precursory phenomena and destructive events related to the Late Bronze Age Minoan (Thera, Greece) and
AD
79 (Vesuvius, Italy) Plinian eruptions; inferences from the stratigraphy in the archaeological areas
Authors: Cioni Raffaello , Gurioli Lucia , Sbrana Alessandro , Vougioukalakis Georges
Published: April 2008

Volcanological studies in the Bronze Age settlement of Akrotiri (Santorini, Greece) and in the Roman towns of Pompeii and Herculaneum (Vesuvius, Italy) have provided information about the precursory phenomena preceding the Minoan and
AD
79 Plinian eruptions and the impact of the eruptive products on the human settlements. The Akrotiri settlement was badly damaged by earthquakes before the onset of the eruption. A building debris layer, related to these earthquakes, covers the Minoan soil. The fallout pumice bed, mantling the ruins, freezes a state of partial destruction of the settlement. The deposition of the following pyroclastic flows completed the covering of the site. Strong seismicity also occurred during the opening and the Plinian phases. At the Herculaneum and Pompeii excavations clear evidence of strong pre- and syn-eruptive earthquakes is absent. Herculaneum, just 7 km west of the crater of Vesuvius, was destroyed by several pyroclastic flows, which buried the town under 20 m of deposits. Pompeii was covered by a 3 m thick blanket of pumice fall deposit. Distal dilute and turbulent ash clouds reached the town toward the end of the Plinian phase, killing all remaining inhabitants. The following turbulent cloud related to the onset of the caldera collapse completely destroyed the town, which was successively covered by the final phreatomagmatic products of the eruption.