bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial and temporal patterns of macroboring within Mesozoic and Cenozoic coral reef systems
Authors: Perry Christopher T. , Bertling Markus
Published: April 2008

Macroboring of coral reefs has varied significantly through time, with the modern intensity and producer composition (usually dominated by sponges) as a rather recent phenomenon. Given the outstanding role and influence of bioerosion on framework morphology, community composition and sediment production, Modern conditions are therefore poor analogues for the structure and function of pre-Neogene reef systems. Modern and Neogene reef borer associations are mostly dominated by sponges, although marked spatial variations in the abundance of borer groups are evident within individual reef systems. Highest diversity typically characterizes low energy, shallow water back-reef or lagoon sites. This condition evolved gradually from the Late Triassic onwards, when scleractinians first built reefs.

Sponges appear to have played a subordinate role in Mesozoic coral-dominated buildups. Worms and barnacles dominate in the early Mesozoic (Triassic and Lower Jurassic), with a progressive increase in bivalve borers through the Jurassic. The paucity of data collected to date makes determination of the causes of temporal change in macroboring community composition difficult to constrain. Macroboring groups seem to have withstood biotic crises much better than their coral substrate and thus reef ecological evolutionary units are not applicable. There is some indication that macroborers may have radiated to colonize new ecological niches during the early stages of coral reef diversification. The development was nonetheless influenced by biotic changes in the marine realm, the strongest effects potentially resulting from switches in nutrient status and the origin or diversification of reef grazers.
El Niño-Southern Oscillation mass mortalities of reef corals: a model of high temperature marine extinctions?
Authors: Glynn Peter W.
Published: April 2008

Protracted high sea temperature anomalies accompanying El Niño-Southern Oscillation (ENSO) events have caused reef-building coral bleaching (loss of zooxanthellae) and mortality in all major coral reef biogeographic regions during the past two decades. Coral reef degradation in the eastern tropical Pacific has resulted from reductions in live coral cover, declines in coral species population abundances, local to regional scale extinctions, disruption of predator/prey spatial relations and relative abundances, bioerosion of reef frameworks, and low coral recruitment. None of the coral species that have suffered regional extinctions has reappeared after 15 years. Intense external and internal bioerosion by fishes, echinoids, lithophagine bivalves and clionid sponges has occurred on reefs affected by the 1982/83 El Niño coral bleaching event, and 1000–5000 year old reef framework accumulations in the Galápagos Islands have been completely eroded and reduced to gravel and sand. Because tropical zooxanthellate reef species are more vulnerable to rising (2–3°C) than falling (8–10°C) temperatures, greenhouse conditions may be more critical in limiting reef growth than icehouse conditions. ENSO warming episodes elicit physiological stress responses resulting in widespread mass coral mortality, leaving scant traces relating to causation. Signals that may help to identify past ENSO disturbances are: (a) temperature-related oxygen isotopic signatures, (b) skeletal stress bands and growth discontinuities, (c) coral debris in beach storm deposits, (d) increases in coral clastics resulting from intensified bioerosion and (e) the skeletal elements of bioeroders. Because this disturbance is the most pronounced and widespread of any known natural perturbation, and may increase markedly in scope with projected global warming predictions, it is considered a likely agent of future and possibly some ancient bioevents.
The Palaeozoic time scale reviewed
Authors: McKerrow W. S. , van Staal C. R.
Published: April 2008

A new revised time scale for the Palaeozoic era is presented on the basis of a compilation of existing U-Pb age data of volcanic rocks associated with zonal fossil-bearing sedimentary rocks.
Palaeomagnetism and Palaeozoic palaeogeography of Gondwana and European terranes
Authors: Tait Jenny , Schätz Michael , Bachtadse Valerian , Soffel Heinrich
Published: April 2008

Neoproterozoic to Late Palaeozoic times saw the break-up of the supercontinent Rodinia, and the subsequent construction of Pangaea. The intervening time period involved major redistribution of continents and continental fragments, and various palaeogeographical models have been proposed for this period. The principal differences between these models are with regard to the drift history of Gondwana, the timing of collision between northern Africa and Laurussia, and formation of Pangaea. Palaeomagnetic evidence provides basically two contrasting models for the Ordovician to Late Devonian apparent polar wander (APW) path for Gondwana involving either rapid north and southward movement of this continent, or gradual northward drift throughout Palaeozoic time. In contrast, palaeobiogeographical models suggest contact between Laurussia and Gondwana as early as mid-Devonian time with the continents basically remaining in this configuration until break-up of Pangaea in the Mesozoic era. This is in conflict, however, with most palaeomagnetic data, which demonstrate that in Late Devonian time, north Africa and the European margin of Laurussia were separated by an ocean of at least 3000 km width. This is also in agreement with the geological record of present-day southern Europe, which argues against any collision of northern Africa with Europe in Devonian time. With regard to formation of Laurussia, however, palaeobiogeographical and palaeomagnetic data are in excellent agreement that by mid-Devonian time the oceanic basins separating Baltica, Laurentia, Gondwana-derived Avalonia and the Armorican Terrane Assemblage (ATA) had all closed. Palaeomagnetic and geological data are also in agreement that the Palaeozoic basement rocks of the European Alpine realm formed an independent microplate, which was situated to the south of Laurussia. In Late Silurian times it was separated by an ocean of
c.
1000 km, and by Late Devonian time was approaching the southern Laurussian margin. According to palaeomagnetic data, the northern margin of Gondwana was still further to the south in Late Devonian time, and according to the geological record in southern Europe, the main continent-continent collision of northern Africa with European Laurussia and closure of the intervening ocean occurred in Late Carboniferous times. Location of this suture is situated to the south of the Palaeozoic alpine units (e.g. the Greywacke zone, Carnic Alps, Sardinia and Sicily), but has been obscured by younger deformational events and cannot be precisely positioned. Assessing available evidence and as discussed in the text, it is proposed that the most likely scenario is that the northern margin of Gondwana drifted gradually northwards from Ordovician to Late Carboniferous times when it collided with Laurussia, resulting in formation of Pangaea.
The mid-European segment of the Variscides: tectonostratigraphic units, terrane boundaries and plate tectonic evolution
Authors: Franke W.
Published: April 2008

The mid-European segment of the Variscides is a tectonic collage consisting of (from north to south): Avalonia, a Silurian-early Devonian magmatic arc, members of the Armorican Terrane Assemblage (ATA: Franconia, Saxo-Thuringia, Bohemia) and Moldanubia (another member of the ATA or part of N Gondwana?).

The evolution on the northern flank of the Variscides is complex. Narrowing of the Rheic Ocean between Avalonia and the ATA occurred during the late Ordovician through early Emsian, and was accompanied by formation of an oceanic island arc. By the early Emsian, the passive margin of Avalonia, the island arc and some northern part of the ATA were closely juxtaposed, but there is no tectonometamorphic evidence of collision. Renewed extension in late Emsian time created the narrow Rheno-Hercynian Ocean whose trace is preserved in South Cornwall and at the southern margins of the Rhenish Massif and Harz Mts. Opening of this ‘successor ocean’ to the Rheic left Armorican fragments stranded on the northern shore. These were later carried at the base of thrust sheets over the Avalonian foreland. Closure of the Rheno-Hercynian Ocean in earliest Carboniferous time was followed by deformation of the foreland sequences during the late lower Carboniferous to Westphalian.

Closure of narrow oceanic realms on both sides of Bohemia occurred during the mid- and late Devonian by bilateral subduction under the Bohemian microplate. In both these belts (Saxo-Thuringian, Moldanubian), continental lithosphere was subducted to asthenospheric depths, and later partially obducted. Collisional deformation and metamorphism were active from the late Devonian to the late lower Carboniferous in a regime of dextral transpression. The orthogonal component of intra-continental shortening produced an anti-parallel pair of lithospheric mantle slabs which probably joined under the zone of structural parting and became detached. This allowed the ascent of asthenospheric material, with important thermal and rheological consequences. The strike slip displacements were probably in the order of hundreds of kilometres, since they have excised significant palaeogeographic elements.
The eastern termination of the Variscides: terrane correlation and kinematic evolution
Authors: Franke Wolfgang , Żelaźniewicz Andrzej
Published: April 2008

Analysis of tectonostratigraphic units in the West Sudetes reveals the same geological events as in the areas west of the Elbe Fault Zone: a late Proterozoic (Cadomian) orogenic event, Cambro-Ordovician to Devonian rift-drift, and late Devonian to early Carboniferous subduction-collision. There is no conclusive evidence of an Ordovician orogenic event. Tectonic units in the Sudetes are shown to be related to terranes defined in western parts of the Bohemian Massif. The Lausitz-Izera Block, the Orlica-Śnieżnik Unit and the Staré Město Belt represent easterly continuations of the Saxo-Thuringian Terrane. The Rudawy Janowickie Unit and the Sudetic Ophiolite contain fragments of the Saxo-Thuringian Ocean. The protoliths of the Görlitz-Kaczawa Unit, the South Karkonosze Unit, the Góry Sowie and the Kłodzko Units either belong to the Bohemian Terrane or else were welded onto it during mid-late Devonian metamorphism and deformation. Relicts of the Saxo-Thuringian Foreland Basin are marked by flysch with olistoliths in the Görlitz-Kaczawa Unit and in the Bardo Basin. The spatial array of terranes in and around the Bohemian Massif reveals a disrupted orocline, dissected by dextral transpression along the Moldanubian Thrust. This orocline was formed when central parts of the Variscan belt were accommodated in an embayment of the southern margin of the Old Red Continent.
The Baltica-Gondwana suture in central Europe: evidence from K-Ar ages of detrital muscovites and biogeographical data
Authors: Belka Z. , Ahrendt H. , Franke W. , Wemmer K.
Published: April 2008

The Lysogory Unit, the Malopolska Massif and the Upper Silesian Massif in southern Poland are parts of a mosaic of contrasting crustal fragments separating the old Precambrian crust of the East European Platform (EEP) from the Phanerozoic mobile belts of western Europe. The geological histories of these blocks are markedly different. They have been regarded as integral parts of the palaeocontinent of Baltica (that is, the EEP), mostly because of presence of fossils typical for the Baltic realm, although geophysical and geological data and some faunal elements rather suggest linkages to the Peri-Gondwana plates. To provide additional constraints for the plate tectonic affinity of these blocks detrital muscovite grains extracted from Cambrian and Devonian clastic rocks were dated by the K-Ar method. The K-Ar cooling ages show a very complex provenance pattern for clastic material in Cambrian time. Combined with the biogeographical constraints, the new provenance data apparently show that the blocks of Lysogory, Malopolska, and Upper Silesia are in fact crustal fragments derived from the Gondwana margin, not displaced parts of the East European Craton. Thus, the Teisseyre-Tornquist Line (that is, the edge of the EEP) is the Baltica-Gondwana suture in central Europe. The combined data reveal an accretionary scenario in which the Malopolska Block was the first Gondwana-derived microplate that accreted to the margin of Baltica.
The Brunovistulian: Avalonian Precambrian sequence at the eastern end of the Central European Variscides?
Authors: Finger F. , Hanžl P. , Pin C. , von Quadt A. , Steyrer H. P.
Published: April 2008

An outline is presented of the present state of research on the Precambrian evolution history of the Brunovistulian, a large (30 000 km
2
), mainly sediment covered Peri-Gondwana basement block at the eastern end of the Central European Variscides. On the basis of recent chemical, isotopic and geochronological data it is argued that the eastern half of the Brunovistulian (Slavkov Terrane) originated in an island-arc environment, documenting the rare case of Neoproterozoic crustal growth in central Europe. The western half of the Brunovistulian, the Thaya Terrane, includes more mature, recycled cratonic material and is considered to have been originally part of the Neoproterozoic Gondwana continent margin. A phase of regional metamorphism at
c.
600 Ma, followed by extensive granitoid plutonism, probably marks the stage when the Slavkov Terrane was accreted to the Thaya Terrane by arc-continent collision. A belt of metabasites, which is intercalated between the two terranes, may represent relics of the incipient arc or a back-arc basin. A comparison of geochronological data shows that the timing of geological events recorded in the Brunovistulian does not correlate with the evolution history of the Cadomian crust in the Teplá-Barrandian zone and the Saxo-Thuringian belt. This supports the theory that the Brunovistulian is not part of Armorica but derived from a different sector of the Neoproterozoic Gondwana margin. A correlation with the Avalonian superterrane appears feasible.
Deformation, metamorphism and exhumation: quantitative models for a continental collision zone in the Variscides
Authors: Seyferth M. , Henk A.
Published: April 2008

Two-dimensional thermo-mechanical finite-element models are used to gain a quantitative insight into the complex strain partitioning in continental collision zones. If models with Moho temperatures of 700–900 °C, as is indicated by petrological data, are simulated, frequently used flow laws for the lower crust cannot reproduce significant crustal thickening. Instead, decoupling between crust and mantle occurs, resulting in the widening of a diffuse deformation zone. To reproduce observed petrological data and orogen geometries, a stronger lower crust, with viscosities between 10
21
and 10
23
Pa s, is required. Models are applied specifically to a collision zone from the Variscan Orogen of Central Europe to understand the tectonometamorphic history, strain partitioning within the collision zone, as well as the rapid synconvergent exhumation of metamorphic complexes. Model predictions agree with the observed distribution of peak metamorphic conditions and show systematic variations of contemporaneous pressure-temperature (
P-T
) paths across the collision zone.
Turbidite basin and mass dynamics related to orogenic wedge growth; the Rheno-Hercynian case
Authors: Ricken W. , Schrader S. , Oncken O. , Plesch A.
Published: April 2008

Investigation of the Rheno-Hercynian Turbidite Basin suggests an interrelation between orogenic wedge migration and changes of the basin architecture, facies types and progradation rates of turbidite systems. The orogenic wedge was built dominantly by the Mid-German Crystalline Rise and accreted older parts of the Rheno-Hercynian Turbidite Basin. Turbidite sequences seem to have developed in stepwise prograding sub-basins. They show systematic trends of widely correlative (tens of kilometres) large-scale cycles that show an upward transition from coarse-grained clastics to highly diluted mud turbidites with highstand shedding of carbonates. These observations suggest the existence of accommodation cycles on the assumed shelf along the Mid-German Crystalline Rise. Exposure of the shelf above sea level was associated with bypass and transport of coarse-grained clastics into the basin, whereas flooding is thought to have caused storage of clastic deposits on the shelf and the simultaneous deposition of mud turbidites in the basin. Accommodation cycles, estimated to reflect an average duration of 10
5
–10
6
a, were probably related to cyclic changes of underthrusting in the internal parts of the orogenic wedge with concomitant uplift. The lifetime and onset of new sub-basins, of the order of a few million years, may show stages of imbricate fan formation. A pattern of major change in sedimentation rates, basin geometry and subsidence style of the Rheno-Hercynian Turbidite Basin and the Sub-Variscan Molasse Basin was interpreted to reflect the different change in crustal strength. This occurred because the hinge line between previously rifted and unrifted crust was overrun during wedge progradation. Numerical mass balance that compares exhumed and intra-basinal masses of the Rheno-Hercynian Turbidite Basin, including the proportional fill of the Sub-Variscan Molasse Basin and the Saar-Nahe Basin, indicates a significant lack of sediment mass (i.e. more than one-third of the exhumed masses). In this estimate, syn- to post-depositional truncation was included. As extension in the internal parts of the orogenic wedge has only a minor role, the above deficit is probably related to subduction of sediment during the early stages of convergence.
Upper-plate deformation during collisional orogeny: a case study from the German Variscides (Saxo-Thuringian Zone)
Authors: Schäfer Frauke , Oncken Onno , Kemnitz Helga , Romer Rolf L.
Published: April 2008

A doubly vergent orogenic wedge system within the Central European Variscides developed during Carboniferous collision of two continental fragments, the northwestern edge of the Saxo-Thuringian upper plate and the Rheno-Hercynian passive margin in the lower plate. The resulting thrust system in the upper plate above the SE-dipping subduction zone retains the memory of the mode of deformation partitioning and material flow pattern in its internal architecture, its kinematic, metamorphic and geochronological record, and its reflection seismic image. New data indicate a stepwise SE-ward progradation of the NW Saxo-Thuringian fold belt with two stages of shortening between about 340 and 335 and between 320 and 310 Ma above a NW-dipping basal detachment. The NW Saxo-Thuringian fold belt is reinterpreted as a retro-wedge that was kinematically coupled to the Rheno-Hercynian pro-wedge and subduction system. The two steps in retro-wedge growth are linked to (a) the onset of collision with the Rheno-Hercynian margin causing upper-plate uplift and (b) a widespread late-orogenic stage of wedge thickening. The retro-wedge accumulated mostly diffuse shortening of > 100 km versus the shortening by imbrication of 180–200 km in the Rheno-Hercynian lower plate. Material advection and orogenic architecture were strongly affected by asymmetric erosional removal towards the lower-plate foreland and by transient mechanical properties of the wedge system.
Geophysical constraints on exhumation mechanisms of high-pressure rocks: the Saxo-Thuringian case between the Franconian Line and Elbe Zone
Authors: Krawczyk C. M. , Stein E. , Choi S. , Oettinger G. , Schuster K. , Götze H.-J. , Haak V. , Oncken O. , Prodehl C. , Schulze A.
Published: April 2008

Major bodies of high-pressure (HP) rocks in the Saxo-Thuringian Belt in East Germany (Saxonian Granulite Massif, Erzgebirge) are investigated using a variety of geophysical methods (seismic reflection and refraction survey, magnetotelluric studies, gravity modelling). The Saxonian Granulite Massif and the Erzgebirge are not a continuous feature, as can be seen from discontinuous reflections, offset of upper-crustal seismic refraction velocity layers, and crustal resistivity increasing towards the Erzgebirge. Their juxtaposition during the evolution of two Variscan-age thrust wedges may have controlled this geometry. The earlier thrust wedge emplaced the supracrustal Erzgebirge HP nappes from the southeast to the northwest onto the Saxo-Thuringian Basin, whereas the later one propagated southwards and uplifted the Saxo-Thuringian granulites from deeper levels. To the southwest, the granulites are observed at shallow depth as far as the Franconian Line; to the southeast they extend down to the Moho, or they continue at mid-crustal levels. The granulites beneath the Saxo-Thuringian Belt can only have originated in one of two subduction zones: either through ‘subduction erosion’ and subsequent underplating of parts of the Saxo-Thuringian Plate from the north, or by intracrustal plug flow of overheated material from the southeast.
Foreland-directed lower-crustal flow and its implications for the exhumation of high-pressure-high-temperature rocks
Authors: Henk Andreas
Published: April 2008

Thermo-mechanical finite element models are used to study foreland-directed lower-crustal flow as a potential process to transport high-pressure-high-temperature (HP-HT) rocks from a continental collision zone to areas that have never experienced crustal thickening or deep burial. The numerical simulations show that lower-crustal rocks can indeed flow over substantial horizontal and vertical distances, provided a thermal anomaly reducing lithospheric strength exists in the foreland. As lower-crustal flow is a fast process compared with conductive heat transport and occurs subparallel to the isotherms, the resulting
PT
path of the rocks exhumed will be characterized by near-isothermal decompression. Modelling results are applied to the Saxonian Granulite Massif in Eastern Germany, where HP-HT granulites have been exhumed beneath a marine sedimentary basin during the Variscan Orogeny.
Hybrids, magma mixing and enriched mantle melts in post-collisional Variscan granitoids: the Rastenberg Pluton, Austria
Authors: Gerdes A. , Wörner G. , Finger F.
Published: April 2008

The composite Rastenberg Pluton in the South Bohemian Massif preserves an example of generation of relatively homogeneous granitoid hybrids by mixing of mafic and felsic magmas. Metaluminous melagranites and quartz monzonites, the main lithologies of the pluton, are interpreted to be hybrids. In contrast, a slightly peraluminous biotite granodiorite is considered to be a lower-crustal melt. In addition, abundant mafic ultrapotassic enclaves, country-rock lamprophyres and quartz monzodiorite bodies represent distinct lithospheric mantle-derived magmas, which were only slightly modified by fractionation and/ or magma mixing. Almost continuous linear chemical and isotope correlations joining the enclaves, quartz monzonites, melagranites and granodiorites indicate the importance of a mixing process in the generation of these rocks. Incompatible elements decrease with increasing silica and moderate negative Eu anomalies disappear towards the granodioritic endmember. Pb, Sr and Nd isotopes show typical crustal values in all granitoids but are more radiogenic in the ultrapotassic endmember. In the Rastenberg Pluton, the interaction of mantle- and crustal-derived magmas has produced unequivocal petrographic, chemical and isotopic evidence for mixing and mingling. Because similar features are lacking in most other Variscan plutons, we suggest that mantle magmas were not substantially involved in their genesis. Nevertheless, small-volumes of hybrids, involving variably enriched mantle-derived melts, do crop out locally throughout the central Variscides. In view of the generally strongly enriched nature of these small volume hybrid magmas, we suggest that voluminous mantle melting and large-scale magmatic underplating are unlikely to have occurred.
A review of Devonian time scales: databases, construction and new data
Authors: Williams E. A. , Friend P. F. , Williams B. P. J.
Published: April 2008

Aspects of the isotopic age and stratigraphical databases underpinning Devonian geological time scales are reviewed to assess differences in recent U-Pb zircon-based schemes and older schemes based on Rb-Sr, K-Ar,
40
Ar-
39
Ar dating of minerals and whole-rock samples. The various methods of time-scale construction are described and, with their databases, 14 calibrations of Devonian time are discussed. Finally, the most recent data are collated and compared against current U-Pb-based time scales.
Coastal-fluvial palaeoenvironments and plant palaeoecology of the Lower Devonian (Emsian), Gaspé Bay, Québec, Canada
Authors: Griffing David H. , Bridge John S. , Hotton Carol L.
Published: April 2008

The Cap-aux-Os Member (of Emsian age) of the Battery Point Formation, Gaspé Bay, Québec, comprises coastal and fluvial deposits containing abundant, well-preserved remains of early land plants (embryophytes). Metres-thick sandstone bodies represent the deposits of the main river channels, including some that were tidally influenced. Thinner sandstone bodies within mudstone successions represent deposits of crevasse splays-levees, lacustrine deltas, tidal channels, flood-tidal deltas and washovers. Mudstone-dominant strata represent backswamps and marshes, lakes, coastal bays and tidal flats. Certain plants (trimerophytes,
Huvenia
and
Sciadophyton
) are particularly common on the moist, upper parts of near-coastal channel bars. They apparently germinated and grew rapidly on freshly exposed muds deposited during floods or exceptionally high tides.
In situ
zosterophylls are most common in backswamp and marshy areas, where they formed extensive, relatively longlived stands. It is uncertain whether these plants were tolerant of brackish water or killed by it. However, absence of acritarchs in these
in situ
plant horizons suggests that they occupied primarily freshwater habitats. Transported
Prototaxites
and
Spongiophyton
, both interpreted as possible fungi, are the main components of fully non-marine channel deposits. It is no coincidence that the best-preserved plants are those that lived in moist, oxygen-poor settings. However, the occurrence of root traces in palaeosols and sparse fossil evidence suggests that embryophytes also occupied drier settings.
Initiation and early development of the Dingle Basin, SW Ireland, in the context of the closure of the Iapetus Ocean
Authors: Boyd J. Douglas , Sloan Roderick J.
Published: April 2008

The Dingle Basin of southwest Ireland lies within 40 km of the present-day trace of the Iapetus Suture. Its late Silurian fill (Dunquin Group and lower Dingle Group) is an important and, in many aspects, unique record of late Caledonian development in the Irish and British sector of the orogen. The upper Wenlock-upper Ludlow Dunquin Group comprises shallow-marine to non-marine siliciclastic and volcanic rocks (acid pyroclastic deposits and predominantly andesitic lavas) deposited on and around a volcanic island(s), whereas the lower, upper Ludlow-Přídolí, part of the overlying Dingle Group comprises sandstones, mudstones and minor conglomerates deposited in lacustrine, lake margin and succeeding fluvival systems. The change from marine Dunquin Group to non-marine Dingle Group (Old Red Sandstone) sedimentation is interpreted to have been tectonically driven. The succession is interpreted in terms of four phases of basin evolution: (1) a phase related to active subduction; (2) a phase related to subduction termination; (3) a post-subduction thermal subsidence phase; (4) a phase of strike-slip fault-controlled subsidence. In the broader, late-Caledonian context, the Dunquin Group volcanic rocks and associated sediments are interpreted as representing localized subduction of a final vestigial portion of Iapetus oceanic crust. The later, inferred, strike-slip influence in the basin is believed to be part of the well-documented regional strike-slip regime affecting this sector of the Caledonides.
A new terrane in the Old Red Sandstone of the Dingle Peninsula, SW Ireland
Authors: Richmond Lorna K. , Williams Brian P. J.
Published: April 2008

We propose the name Northwest Dingle Domain for the enigmatic Old Red Sandstone terrane whose tectono-sedimentary evolution has perplexed generations of geologists. The Domain remained largely misinterpreted, unappraised or simply disregarded, and its fundamental impact on regional basin dynamics was grossly overlooked. The Northwest Dingle Domain is largely structurally constrained between two ENE-trending Caledonian structures: the North Kerry Lineament and the Fohernamanagh Fault. It comprises four unconformity-bounded Groups: the Lower Devonian Smerwick Group; the Middle Devonian Pointagare Group; and the Upper Devonian Carrigduff and Ballyroe Groups. Their fluvial-aeolian, and locally tidal, sedimentation patterns profile Late Caledonian transpression to Mid-Late Devonian extension. The inherent primary structural control on basin location, development, geometry, sedimentary-fill and preservation is manifest in the Northwest Dingle Domain. The Acadian emplacement of the Smerwick Group set the foundations of the Northwest Dingle Domain. The Smerwick Group documents sandy and gravelliferous ephemeral-fluvial and erg-margin aeolian processes on an ancient terminal fan(s). The Pointagare Group is cogenetic with the Caherbla Group of south Dingle. Together they record the renewed influx of coarse-grained sediment in the form of transverse alluvial fans and axial braidplains in response to increased tectonism followed by overstep of an erg complex. The Pointagare-Caherbla basin model highlights the fundamental structural control on basin topography, palaeodrainage patterns, provenance, palaeowind directions and sedimentation style in tectonically-active extensional basins.
Wide-angle seismic control on the development of the Munster Basin, SW Ireland
Authors: Vermeulen N. J. , Shannon P. M. , Masson F. , Landes M.
Published: April 2008

Three wide-angle seismic profiles were acquired from onshore southern Ireland during VARNET-96. These data provide the only subsurface seismic images of a series of predominantly Late Palaeozoic sedimentary basins. The Dingle Basin is a broadly symmetrical rift on the Dingle peninsula, but assumes a half-graben geometry to the east. The southern syn-rift basin margin is defined by the north-dipping Dingle Bay-Galtee Mountains Line. A south-dipping normal fault at Kerry Head marks the northern basin margin in the west, with displacement on this structure decreasing towards the east. The Dingle Basin is separated from the Munster Basin to the south by a basement horst. Seismic data strongly suggest that the Killarney-Mallow Fault Zone, located on the southern margin of this positive feature, is the Munster Basin northern syn-rift marginal fault. The preserved extensional displacement on this detachment decreases from
c.
2.5 km in northern Iveragh, to
c.
1 km at Mallow, suggesting that the fault tips out to the east of Mallow. A tilted fault block, possibly cored by shallow granite, is imaged in the northern Munster Basin. This fault terrace is bounded to the south by the Cork-Kenmare Line. The combined Munster Basin and South Munster Basin succession thickens across the Cork-Kenmare Line to a maximum thickness of 8 km on the Beara peninsula. A tectonic thickness of 6 km of sediment is modelled at the Old Head of Kinsale, increasing to 7 km in the southwest.
Flexural cantilever models of extensional subsidence in the Munster Basin (SW Ireland) and Old Red Sandstone fluvial dispersal systems
Authors: Williams E. A.
Published: April 2008

Flexural cantilever (2D) computer modelling of the palinspastically restored Mid-Late Devonian Munster Basin has been used to appraise quantitatively extensional subsidence and Old Red Sandstone (ORS) stratigraphic geometries. One-dimensional decompaction and (Airy isostatic) backstripping were carried out to constrain syn-rift forward models; these specify the Late Palaeozoic rifting history of the region. Forward modelling showed that listric faults and detachments fail to reproduce restored ORS sediment geometries, but instead indicated that multiple planar, upper-crustal faults are necessary to achieve the correct order of syn-rift subsidence across the basin. Modelled (non-unique) sections transverse to the basin bounding fault (Dingle Bay-Galtree Fault Zone) replicated ORS geometries with cumulative extensions of 27 km in the east (stretching factor β = 1.3) and 59 km in the west (β = 1.48), with effective elastic thicknesses of 7 and 8 km, respectively, starting from a 40 km thick post-Acadian crust. Resultant peak heat-flow anomalies predict well the location of known syn-rift volcano-magmatic centres. Modelling indicated that significant offshore faults are required to achieve subsidence in the west Cork region, implying that the basin continues offshore. Observed ORS (<0.85 km thick) sections on the regional footwall, considered to be the result of thermal (post-rift) subsidence, are not accounted for by modelling, whereas
c
. 1 km of post-rift ORS is modelled over 5 Ma in the central-southern regions of the basin. These sections buried the principal rift faults during late Famennian time. The ORS of the Munster Basin is dominated by two large-scale transverse fluvial dispersal systems that were largely insensitive to deflection by any extension faults that propagated in the syn-rift fill. A third major system entered in the SW, demarcated by antithetic extension faults south of the depocentre.
U-Pb zircon geochronology of silicic tuffs and chronostratigraphy of the earliest Old Red Sandstone in the Munster Basin, SW Ireland
Authors: Williams E. A. , Sergeev S. A. , Stössel I. , Ford M. , Higgs K. T.
Published: April 2008

Newly acquired U-Pb magmatic zircon dates from silicic tuffs within the Old Red Sandstone (ORS) magnafacies of the Munster Basin (SW Ireland) are intercalibrated with newly discovered (late Givetian) and reappraised (mid-Frasnian) miospore assemblages to provide the first biostratigraphically constrained numerical ages in the Irish Devonian succession. The weighted mean
207
Pb/
206
Pb isotopic age determined for the Keel Tuff Bed (385.0±2.9 Ma) is indistinguishable from that of the previously investigated Enagh Tuff Bed (384.9±0.7 Ma). In conjunction with very similar rare earth element (REE) signatures, this confirms their correlation, placing a minimum age of 384.9±0.4 Ma on the newly discovered Reenagaveen microflora, which is assigned to the late Givetian TCo Oppel zone. The equivalence of the Keel and Enagh Tuffs constrains a vertebrate fauna containing
Bothriolepis
and the Valentia Island tetrapod ichnofauna to pre-date this event. Isotopic dating of thickly bedded subaerial tuffs from the Lough Guitane Volcanic Complex, a major accumulation of rhyolites and silicic volcaniclastic rocks, reveals ages of 384.5 ± 1.0 Ma (Killeen Volcanic Centre), indistinguishable from the Keel-Enagh Tuff Bed, and 378.5±0.2 Ma from the Horses Glen Volcanic Centre, previously considered to be the oldest of the complex. The Horses Glen Centre post-dates the Moll’s Gap Quarry microflora, the only current biostratigraphical control on the age of the early ORS in the east of the basin depocentre, thus indicating a minimum age for the (mid-Frasnian) IV Oppel zone, the revised biostratigraphic age of this assemblage. These controls on the early ORS (1) suggest that Munster Basin initiation occurred before late Givetian time and (2) give time-averaged (compacted) accumulation rates of
c.
0.17–0.25 and 0.18 mm a
−1
for eastern and western Iveragh, respectively. The minimum basin duration time was
c.
23 Ma to the end of the Devonian period. The implications of these data for the depocentre stratigraphy, volcanic events, proposed ORS cyclicities and the geohistory of the Munster Basin are examined.
Controls on magmatism in the Munster Basin, SW Ireland
Authors: Pracht M.
Published: April 2008

The following paper is intended as a review of the magmatism in the Munster Basin and an initial attempt to link it with the basin’s history. During the initiation, evolution and inversion of the Devono-Carboniferous Munster Basin magmatic activity was widespread, although small in volume. The episodic occurrence and diversity of the magmatism gives insights into the basement involvement and structural controls relating to the basin’s history. The differences in composition, location and structural relationship of the magmatic bodies are used as indicators for the timing of their emplacement and their relationship to the basin’s evolution. On the western Beara Peninsula in SW Ireland alone, more than 160 sheet-like intrusions, a wide variety of tuff bands and a deep-seated pipe-like structure of lamprophyric affinity occur. Other centres of magmatism in the basin are the Lough Guitane area, where rhyolitic lava flows and acidic pyroclastic rocks are associated with contemporaneous basin faults, and the Valentia Harbour area, where doleritic sills are associated with a volcanic breccia. A rhyodacitic tuff can be traced as far as St Finan’s Bay on the western shore of the Iveragh Peninsula. The chemical composition of the extrusive and intrusive magmatic bodies ranges from tholeiitic dolerites (Valentia Harbour) and subalkaline rhyolites (Lough Guitane) in Mid-Devonian time to subalkaline basalts and tuffs (e.g. Beara Peninsula) in Late Devonian time. In Late Carboniferous and possibly Permian time alkali basalts, trachytes and phonolites (e.g. Beara Peninsula) occur. The igneous activity in the Munster Basin is linked to the basin’s history by the interaction between active faults and fractures opening up during various stages of stress imposed on the basin and exploitation of these faults and fractures by rising magma.
Silurian marginal marine sedimentation and the anatomy of the marine-Old Red Sandstone transition in Pembrokeshire, SW Wales
Authors: Hillier Robert D.
Published: April 2008

Deposition of the Silurian (Wenlock) siliciclastic Gray Sandstone Group of southwest Pembrokeshire took place within littoral environments close to the palaeogeographical shelf-margin of the Welsh Basin. Sedimentation described a northerly, basinward progradation across an earlier Late Ordovician? to Aeronian rift basin. Changes in relative sea level (rsl) had profound effects on depositional environments, and five depositional sequences are recognized. During highstands of rsl, the area was influenced by wave-dominated, shallow-marine conditions. During lowstands of rsl, shelf incision and sediment bypass occurred. Associated valley fills vary in nature from high-sinuosity estuarine channels, tidal flats and tidally-influenced, high-sinuosity fluvial channels. The last of these predominate within the youngest sequence, with abundant subaerial emergence indicators heralding the onset of true continental deposition, and the conformable transition into the overlying Old Red Sandstone Red Cliff Formation within the Marloes Peninsula. A renewal of tectonic activity ensued within the Lower Old Red Sandstone, with pebbly low-sinuosity alluvium of the Albion Sands Formation, and fanglomerates of the Lindsway Bay Formation refecting reactivation of earlier rift-margin faults, probably within a transtensional tectonic regime.
Fault-bounded basin fill: fluvial response to tectonic controls in the Skrinkle Sandstones of SW Pembrokeshire, Wales
Authors: Marshall J. D.
Published: April 2008

The Upper Devonian to Lower Carboniferous Skrinkle Sandstones of the Pembroke Peninsula are predominantly continental deposits from the post-Caledonian syn-rift succession at the southern margin of the Late Palaeozoic Welsh Landmass. The Sandstones record deposition in the 30 km × 10 km Tenby-Angle fault block, the southernmost of a series of fault-bounded depositional basins in SW Dyfed. Activity on the bounding faults strongly influenced sedimentation through Lower Palaeozoic time. The Skrinkle Sandstones are conventionally assigned to a phase of relative fault inactivity, passive transgression of the area and southward drainage off the landmass. The Ritec Fault at the northern block boundary defined a temporary shoreline during final submergence. In contrast to this, it is argued that the lower half of the Skrinkle Sandstones represent a separate structural configuration, where SE-directed palaeocurrents and the high textural maturity of two superimposed basin-fill sequences indicate axial basin fill and potential closure to the south. The upper half records an influx of immature clastic deposits as fluvial sediments that disperse to the southwest, indicating relative uplift of either the Ritec or a more northerly fault. This phase records the true transgression, during which a thick barrier-lagoon coastline is preserved against the footwall ramp of the Ritec Fault.
Palaeoecology and plant succession in a borehole through the Rhynie cherts, Lower Old Red Sandstone, Scotland
Authors: Powell Clare L. , Trewin Nigel H. , Edwards Dianne
Published: April 2008

A cored borehole through the Early Devonian Rhynie cherts at Rhynie, Aberdeenshire, NE Scotland, has revealed 53 chert beds in 35.41 m of core. The cherts originated as sinters deposited by hot-spring activity. Chert comprises 4.20 m of the cored succession, with the thickest bed, representing a single silicification event, being 0.31 m thick and the thickest composite chert (comprising six beds) 0.76 m thick. Average chert bed thickness is 80 mm. Forty-five plant-bearing chert beds are interbedded with sandstones, mudstones and shales. The sediments were deposited on an alluvial plain with local lakes, the area being periodically affected by hot-spring activity. Plants initially colonized both subaerial sand and sinter surfaces.
Rhynia gwynne-vaughanii
and
Horneophyton lignieri
commonly form the basal parts of the profiles with subsequent colonization by other genera.
Rhynia
is commonly found in life position above originally sandy substrates, and
Horneophyton
above sinter surfaces. The composition of the Rhynie vegetation is compared with coeval assemblages and, on the basis of current knowledge, it is concluded that there is no unequivocal evidence that the plants were adapted to life in the stressed environments in the immediate vicinity of hot springs.
Devonian (Givetian) miospores from the Walls Group, Shetland
Authors: Marshall J. E. A.
Published: April 2008

Miospores demonstrate that the Walls Group of West Shetland is of early and possibly in part late Givetian age (Late Mid-Devonian age). This is both substantially younger in age and of a shorter duration than previously estimated. The correlative rocks of the Walls Group are those of southeast Shetland, Fair Isle, the Eday Group of Orkney and the John O’Groats Sandstone Group of Caithness. The two formations of the Walls Group are, at least in part, time equivalent rather than a stacked sequence. The total thickness of sediment is likely to be much less than the generally cited 12 km, given the short time duration represented by the single miospore assemblage identified throughout the succession. The low diversity of the miospore assemblage and its fluctuating dominant species is interpreted as reflecting a local vegetation source in a low preservation environment. The age and thermal maturity contrast between the Walls Group and the sedimentary successions to the west (Melby, Papa Stour and Foula) provide further constraints on the movement history along the St Magnus Bay Fault system.
Fossils from the Celsius Bjerg Group, Late Devonian sequence, East Greenland; significance and sedimentological distribution
Authors: Clack J. A. , Neininger S. L.
Published: April 2008

Recent collections of fossils from the Upper Devonian sequence of East Greenland have increased our understanding of the origin and evolution of limbed vertebrates (tetrapods). An expedition in 1998 collected additional material to study the faunal and sedmentological context of the vertebrates from the Celsius Bjerg Group. Specimens collected include new, articulated material of ichthyostegids, a skull of the lungfishJarvikiaand the first record of acanthodian spines and scales. Invertebrates were found in these formations for the first time. Vertebrates occur most often in flood-scours, transported from elsewhere and usually disarticulated. Occasionally, more complete specimens occur, which may have been either desiccated before transport or come from more local environments.
Climatic oscillations versus environmental changes in the interpretation of Tertiary plant assemblages
Authors: Kvaček Zlatko
Published: April 2008

Zonal plant communities are the best climatic indicators because they thrive under specific climatic conditions. However, palaeoclimatic estimates based on mere comparisons of local fossil plant assemblages, even if assessed by multivariate methods, may be misleading, if the taphonomical bias is neglected. The fossil record expresses only limited parts of the vegetation of a given period. The example of the Lower Miocene section at Bílina, North Bohemian Basin, shows how quickly the composition of the plant megafossil record changes as a result of different environmental factors and sedimentary settings. These changes can imitate climatic oscillation because swamp, fluvial and upland facies represented within this site have different vegetation-palaeoclimatic aspects. On the other hand, if one compares two assemblages originating from the same sedimentary and environmental setting (preferably mesophytic conditions), the resulting palaeoclimatic changes can be estimated more safely. Two local assemblages from the Oligocene volcanic area of the České středohoří Mts in North Bohemia are of mesophytic character. Both are embedded in diatomites deposited in crater-maar lakes. The assemblage of Suletice (20–29 Ma), with prevailing thermophilous elements, indicates more warm-temperate conditions, whereas the assemblage of Bechlejovice (27 Ma), composed mostly of deciduous broad-leaved trees and shrubs, corresponds to a temperate climate. Thus, together, these two floral assemblages suggest that a climatic oscillation occurred within Late Oligocene time in Central Europe.
Large mammal turnover pulses correlated with latest Neogene glacial trends in the northwestern Mediterranean region
Authors: Azanza B. , Alberdi M. T. , Prado J. L.
Published: April 2008

From the latest Miocene to the Holocene period, three biotic events in the large mammal communities of the western Mediterranean region show significant and robust diversity changes and/or turnover with respect to sampling, and correspond in time to significant pulses of the latest Cenozoic glaciations. The ‘Ruscinian mammal turnover pulse’ represents a major biotic event close to the ‘Messinian salinity crisis’. This can be described more as a turnover than a dispersion event. The pattern of turnover shows a significantly high value of first appearances close to the Mio-Pliocene transition; last appearances were also important but reduced significantly in the following interval. A Southern Hemisphere glaciation event has been related to the Messinian crisis. The second major biotic event corresponds to the so-called ‘
Equus
-elephant event’ during early Villafranchian time. The relevance of this dispersal event is proved by a marked increase in diversity as a result of a high number of first appearances. Between 3.0 and 2.6 Ma the onset of bi-polar glaciations occurred, followed by glacial-interglacial cycles of moderate amplitude sustained at the orbital periodicity of 41 ka. The last major biotic event was the ‘Galerian mammal turnover pulse’ around 1.0 Ma. This turnover represents an important community reorganization that marks a total rejuvenation of the fauna and is coincident with the arrival of
Homo
species in the western Mediterranean region. At this time, glacial maxima became more extreme and the dominant periodicity of variation shifted to 100 ka, which is attributed to the massive Northern Hemisphere ice sheets.