bluuebunny/crossref_metadata_2025_split huggingface dataset:
Precambrian to Tremadoc biotas in the Caledonides
Authors: Conway Morris S. , Rushton A. W. A. 
Published: September 2007

Summary
The early Phanerozoic faunas of the Caledonides (late Precambrian to Tremadoc) are reviewed; they reflect the early history of the Iapetus Ocean. The long-established distinction between ‘Pacific’ and ‘Atlantic’ faunas is justified, but the latter are divisible into Avalonian and Baltic sub-faunas. Putative deep-water faunas have a more cosmopolitan distribution. Five time segments are considered: late Precambrian (Vendian), early, middle and late Cambrian, and Tremadoc. In the late Precambrian, consideration is given to the distribution of soft-bodied Ediacaran faunas. In the Cambrian and Tremadoc, interpretations are based primarily on trilobite distributions, although other fossils have biogeographical importance. Supposed transgressive-regressive cycles, which are connected with eustatic sea-level changes, influence faunal distributions. The perturbations giving rise to the biomeres recognized around the N American craton also appear to be recognizable elsewhere in the Caledonides; they may reflect eustatic changes of sea level.
Plutonism and volcanism related to the pre-Arenig evolution of the Caledonide-Appalachian orogen
Authors: Rankin D. W. , Furnes Harald , Bishop A. C. , Cabanis B. , Milton D. J. , O’Brien S. J. , Thorpe R. S. 
Published: September 2007

Summary
Igneous activity younger than 1 Ga related to crustal extension characterizes the western part of the orogen from N America to Scotland in the Laurentian plate and the eastern part of the orogen in Scandinavia in the Baltic plate. Sub-aerial tholeiites, locally with alkalic rhyolites at embayments, and accompanying mafic dyke-swarms indicate late Proterozoic continental rifting; oceanic tholeiites followed. Iapetus oceanic crust is preserved in ophiolites obducted to the W in Laurentia and to the E in Baltica. Ensimatic island arcs developed locally in late Cambrian and early Ordovician in Scandinavia were broadly coeval with plutonic rocks intruding continental-shelf sediments during the late Finnmarkian deformation in northern Norway. E of the Iapetus suture in N America, southern Britain and northern France many of the igneous rocks of the accreted terranes underwent or were generated during a late Proterozoic orogeny (Avalonian or Cadomian). Locally fossiliferous lower Cambrian strata rest unconformably on calc-alkaline Avalonian or Cadomian granites.
Type I, or cratonal, terranes formed the rifted margins of the Iapetus Ocean. Type II, or accreted, terranes appear not to have been part of the Iapetus rifting cycle and are not now tied stratigraphically to any large cratonal masses. Type II terranes terminate northward against the projection of Tornquist’s line which may have originated in the late Proterozoic as the southern rifted margin of Baltica.
Arenig to Llandovery faunal distributions in the Caledonides
Authors: Fortey R. A. , Cocks L. R. M. 
Published: September 2007

Summary
Faunal distributions in the Arenig to Llandovery period can be seen to be due to an interplay of the following factors: (i) the biofacies and community distributions on the shelves and slopes of continental margins; (ii) the distribution of former continental masses relative to palaeolatitude; (iii) the contemporary transgressive-regressive cycles which cause diachronous shifts of biofacies belts (with a major crisis at the Ordovician-Silurian boundary); (iv) differential dispersal methods and rates of the different invertebrate groups. The distribution of the common brachiopods, trilobites, graptolites and conodonts exemplify these various influences, and these distributions are considered from both the margins and the central areas of the Caledonides. Palaeogeography cannot be reliably reconstructed without due consideration of all these factors which give results which are relatively independent of structural studies.
Palaeontological evidence bearing on the Arenig-Caradoc development of the Iapetus Ocean basin
Authors: Neuman Robert B. 
Published: September 2007

Summary
Ophiolitic rocks of the Dunnage-Dundee terranes and deep-water sedimentary rocks in the Gander-Greenore terranes indicate the position of the Iapetus Ocean in the Appalachian-Caledonide orogen during the Late Precambrian and Early Ordovician. The few occurrences of fossiliferous Cambrian to Tremadocian peri-insular limestones in the Dunnage terrane suggest a relatively narrow ocean basin within low palaeolatitudes. Late Arenig-early Llanvirn islands in Dunnage and Gander terranes and their equivalents were more abundant; most have little limestone and distinctive Celtic faunal assemblages of middle to high palaeolatitudes, but two (Glensaul-Tourmakeady, central western Ireland, and Hølonda, central western Norway) have abundant limestone and Scoto-Appalachian fossils of low palaeolatitudes. During the obduction of Iapetus Ocean crust, Celtic faunas were replaced by late Llanvirn-Llandeilo warm-water assemblages, indicating movement of these terranes into low palaeolatitudes.
Ordovician to Silurian volcanism in the Appalachian—Caledonian orogen
Authors: Stillman C. J. 
Published: September 2007

Summary
Ordovician to Silurian volcanism in the orogen was primarily associated with the change from a spreading to a closing ocean basin and with the converging margins which involved the development of volcanic arcs, marginal basins and active continental margins as arc-trench systems approached and in some cases were subducted beneath the continental crust. Volcanism was controlled by plate-margin dynamics which differed according to the margin concerned but show remarkable similarities along the length of the orogen.
Arenig to Wenlock volcanism in N America, the British Isles, Europe and Scandinavia are surveyed in this paper in the framework of current plate-tectonic models, and the value of volcanic rocks in tectono-stratigraphic compilation is demonstrated.
Extensive destruction of oceanic crust and margins took place during major Ordovician orogenic events but, although parallel developments on both margins of Iapetus are noted, these events were not synchronous. Similarly, whilst subsequent volcanism was produced by both subduction-related and within-plate activity in most regions, the differences in the timing of this activity lend support to the concept of terrane accretion for the assembly of crustal blocks which make up the Caledonide orogen in its entirety.
Timing of Ordovician deformation in the Caledonian-Appalachian orogen
Authors: Hall Leo M. , Roberts David 
Published: September 2007

Summary
Evidence for Ordovician deformation is variably present throughout the Caledonides. The Grampian (late Cambrian-early Ordovician) and Taconian (middle to late Ordovician) major orogenies occurred during this time period and involved plutonism and metamorphism as well as deformation. The Taconian is particularly important in N America, whereas the Grampian (Penebscot), although locally identified, seems less important. Conversely, the Grampian appears to be more important in Scotland and in Scandinavia, where it is termed the Finnmarkian and constituted a major orogenic phase. Subduction and oceanic closure seems to have been an important Ordovician process, as indicated by abundant ophiolites. In Scandinavia the principal phase of thrust emplacement of the ophiolites occurred in the early to middle Ordovician. Major deformation in central E Greenland is of late Ordovician age.
Arenig to Wenlock age metamorphism in the Appalachians
Authors: Laird Jo 
Published: September 2007

SummaryArenig to Wenlock age metamorphism is best defined in the western part of the Appalachian orogen but may well be preserved in some terranes to the E that are underlain by basement which is not N. American regional metamorphism is primarily medium pressure, but low- to medium-pressure facies series metamorphism also occurs in the central Appalachians, and high-pressure metamorphism is locally preserved in northern Vermont and adjacent Quebec. Metamorphic grade varies from prehnite-pumpellyite to granulite facies; the isograds are generally parallel to the regional NE structural trend. Delimitation of the isograds has been hampered by widespread polymetamorphism, uncertainties in interpretation of field and isotopic data, and the need for more detailed mapping and petrological studies.
A brief review of early Ordovician to Devonian plutonism in the N American Caledonides
Authors: Wones David R. , Sinha A. K. 
Published: September 2007

Summary
The distribution of mafic and felsic plutonic rocks has been used to constrain tectonic and thermal events in portions of the N American Caledonides. In the central and southern Appalachians studies of plutonic rocks identify an early island-arc environment followed by an episode of melting during over-thrusting. Devonian plutonism can be associated with both decompressional melting and rifting. The northern Appalachians also show evidence of early island-arc activity followed by collision of the N American plate with a collection of oceanic arcs and continental fragments. Devonian plutons reflect a more static environment (rift?) where incremental melting of a protolith provides the observed variations in the composition of the magmas.
Timing of Silurian to middle Devonian deformation in the Caledonides of Scandinavia, Svalbard and E Greenland
Authors: Roberts David 
Published: September 2007

Summary
Polyphase orogenic deformation in Scandinavia during the period from early Silurian to middle Devonian time is concentrated in the time-range late Llandovery to early Devonian—the Scandian orogenic event. Deformation and metamorphism began earliest in the western internal parts of the orogen and shifted progressively eastwards to southeastwards towards the external foreland. Early SE-directed high-temperature ductile thrusting was succeeded by imbrication in several areas. In Svalbard the principal tectonothermal event is of middle to late Silurian age. Stratigraphical and isotopic evidence from the E Greenland Caledonides favours a latest Ordovician deformation and metamorphism in central regions, whereas the main deformation and thrusting in the extreme NE occurred during the middle Silurian.
Scandian-Acadian-Caledonian
sensu strictu
metamorphism in the age range 430–360 Ma
Authors: Robinson Peter , Tracy R. J. , Santallier D. S. , Andreasson P.-G. , Gil-Ibarguchi J. I. 
Published: September 2007

Summary
Metamorphism in the age range Wenlock to mid-Devonian, when it can be recognized, appears to have accompanied some of the most intense phases of convergent tectonics in the orogen. Very different styles of metamorphism in different regions suggest different tectonic settings. In Scandinavia deep subduction and imbrication of the Baltic continental margin beneath N America (?), with little or no plutonism, produced a regional pattern leading to high temperature eclogites and granulites. In the British Isles, Canada and Maine, broad greenschist, prehnite-pumpellyite and lower-grade metamorphism accompanied the closure of Iapetus, with local higher-grade punctuations associated with widespread plutonic activity. In France, locally in Newfoundland, in southern New England and in part of the southern Appalachians both plutonic heating and intense deformation were involved in metamorphism to the amphibolite and locally the granulite facies, complicated in France by eclogites and locally by glaucophane schists.
Silurian-Permian palaeocontinental reconstructions and circum-Atlantic tectonics
Authors: Kent D. V. , Keppie J. D. 
Published: September 2007

Summary
On the basis of the palaeomagnetic record, supplemented by constraints provided by faunal and tectonic information, reconstructions involving Laurentia, Baltica, Gondwana and numerous continent-like fragments and terranes within the circum-Atlantic Palaeozoic orogenic belts are made for three critical time intervals, late Silurian, early Carboniferous and late Carboniferous-early Permian, all of which bracket important phases of tectonic activity. The late Caledonian-Scandian-Acadian-Ligerian orogenies are due to the predominantly E-W final closure of Iapetus. This phase was followed in mid-Devonian times by a major sinistral megashear along the orogen which eliminated latitudinal separations and resulted in a Pangea-like assembly by the latest Devonian. The final phase involved a rotation of Gondwana with respect to the assembled Euramerican landmass, expressed as late Variscan-Hercynian dextral shear from central Europe to northeastern N America and culminating in the late Carboniferous-Permian Alleghanian orogeny in the Appalachians from New England S and in the Mauritanides.
Caledonian folding in the Bohemian Massif
Authors: Chaloupský J. 
Published: September 2007

Summary
The Bohemian Massif was formed by metamorphic and tectonic processes during a long period which began about 800–900 Ma ago with the break-up of the ancient continental crust and Brioverian rift sedimentation and ended at the close of the Palaeozoic by transition to the platform-development stage. Caledonian folding has been evidenced in the NE part of the Massif.
The third synthesis: Wenlock to mid-Devonian (end of Acadian orogeny)
Authors: Hatcher Robert D. 
Published: September 2007

Summary
Major deformational-thermal events occurring during the Wenlock to mid-Devonian interval include the Acadian (N America, France, Spain) and the Scandian. These events are possibly related to the closing of the Iapetos Ocean between Laurentia and Baltica and the suturing of the Avalon microcontinent and other smaller terranes to N America. Metamorphism, plutonism and deformation during this interval resulted from the convergence events. Metamorphic grade and intensity of deformation vary spatially throughout the orogen. Both felsic (I-, S- and A-type granites) and mafic plutonism were abundant in N America in the Acadian, but Scandian metamorphism produced relatively little plutonism, most of which was felsic (I-type granites). Volcanic activity was restricted during this time, occurring in Scotland with substantial amounts in E Greenland, the Canadian Maritimes and New England with minor marine tholeiitic volcanism in SW England, France and Germany.
Basement-cover relationships in the Appalachian-Caledonian-Variscan orogen: mid-Devonian (end of Acadian orogeny) to end of Permian
Authors: Hatcher Robert D. 
Published: September 2007

Summary
The Alleghanian-Variscan orogen was, in part, superimposed upon continental crust produced by earlier Palaeozoic orogenies from continental platform and slope and rise sediments volcanic rocks, together with island arcs, rift volcanic rocks and sediments from diverse sources and older Precambrian basement. The effects of the Alleghanian-Variscan orogeny are particularly marked in the southern half of the Palaeozoic mountain chains of N American and western Europe. The Alleghanian-Variscan event(s) produced both ductile and brittle deformation involving folding and faulting (both thrust and strike-slip). Movement along many of these faults produced large displacements of the order of tens to hundreds of kilometres. Large-scale transport on thrusts in the southern and central Appalachians and NW and W Africa (Mauritanides) probably resulted from collision related to final closing of the Theic Ocean. Dominant thrust transport in the southern and central Appalachians contrasts with dominant large-scale strike-slip motion in the Maritime Appalachians of Canada and transpressive motion in the Variscides of western Europe. The character of Variscan deformation in Europe suggests that the orientation of boundary stresses there was somewhat different from those in N America. Late Palaeozoic thrusting in southeastern N America and northwestern Africa suggests that collision was normal there but it may have been oblique in western Europe. However, thrusting occurs along both the northern (Ireland, Wales, Belgium) and southern (France, Iberia) flanks of the Variscan orogen in western Europe. Large-scale over-thrusting of basement and cover rocks in the Rheinisches Schiefergebirge has also been suggested. The basement appears to have responded homogeneously in large domains with major differences in style related in part to stress orientation.
Late Palaeozoic sedimentation along the Appalachian orogen
Authors: Thomas William A. , Schenk Paul E. 
Published: September 2007

SummaryThe sedimentological framework of post-Early Devonian strata in the Appalachians includes two different domains. S of the New York recess in the foreland fold-thrust belt, clastic wedges of two different ages (Devonian-Early Mississippian and Late Mississippian-Pennsylvanian) constitute the sedimentological record of the Acadian and Alleghanian orogenies. The widespread semicircular clastic wedges prograded cratonward across broad foreland basins from orogenic provenances. Distribution of siliciclastic sediments suggests a genetic relation to large-scale curves (salients and recesses) of the orogenic belt and indicates variation in time of orogeny along strike. N of the New York recess in the more interior part of the orogen, Devonian to Permian siliciclastic sediments derived from local fault-block uplifts filled and overflowed pull-apart basins associated with mainly dextral wrench faults. The history of sediment supply and deposition varies from basin to basin. Parts of the northern domain are covered by more widespread siliciclastic sediments. Differences in the two domains reflect not only variation along strike in time of orogeny but also a range of structural style from large-scale cratonward thrusting in the S to wrench faulting in the N.
Devono-Carboniferous river systems and sediment dispersal from the orogenic belts and cratons of NW Europe
Authors: Leeder Michael Robert 
Published: September 2007

Summary
Facies, palaeocurrent and provenance analysis combine to give vital information concerning hinterland tectonic events, particularly when continental facies are used to assess orogenic and/or epeirogenic uplift. In Palaeo-Europa steady progress has been made in this area but much integrative tectono-sedimentary study is still needed. Six palaeogeographic maps are presented in the paper with continental/alluvial facies (‘molasse’) and turbiditic continental margin facies (‘flysch’) mapped out. Palaeocurrent data is ‘distilled’ to highlight impressions of terrestrial drainage trends. Clastic wedges are identified within basins caused by major tectonic events, and include the following: (a) Lower—Middle Devonian successor basins within the Caledonides (fore-arc and inter-arc types, and Pannonian types); (b) Lower Devonian-Lower Carboniferous back-arc and foreland tilt block basins related to lithospheric stretching caused by Acado-Ligerian subduction and collision; (c) Upper Devonian-Upper Carboniferous foreland basins formed by diachronous closure of the Rheno-Hercynian back-arc successions by thrust stacking; (d) Middle-Upper Carboniferous passive thermal cooling of the stretched Caledonian lithosphere; (e) final Upper Carboniferous collision of Gondwanaland and tightening of the Ibero-Armorican arc. No tectonic explanation is yet forthcoming for the growth and development of the huge ‘Pennine’ drainage system which dominated sedimentation over large areas of Ireland, Scotland, England and the North Sea during Middle-Upper Carboniferous times.
Middle Devonian to Permian plutonism and volcanism in the N American Appalachians
Authors: Don Hermes O. , Murray Daniel P. 
Published: September 2007

Summary
Mid-Devonian to late Palaeozoic igneous activity in the N American Appalachians occurs in the eastern portions of the orogen. Represented radiometric ages are almost continuous from 250 to 370 Ma and older, thus overlapping Acadian and Alleghanian orogenic events. In many instances igneous activity is generally similar to that initiated earlier in the Palaeozoic. Plutonic rocks consist of granitoids with subordinate intermediate to mafic rocks. Plutonism is mainly of ‘Caledonian’ or alkalic variety and is dissimilar to subduction-related magmatism of the Andean type. Regional synthesis indicates that some general distinctions of plutonism occur across strike as well as along strike from S to N within the orogen in eastern N America.
In the southern Appalachians granites and minor contemporaneous gabbros occur in all lithotectonic zones between the Blue Ridge and the Coastal Plain. These plutons are commonly syn-kinematic in the eastern Piedmont where Alleghanian deformation and metamorphism are best exhibited, but are late- to post-kinematic to the W. The rocks include metaluminous biotite and megacrystic granites and lesser peraluminous two-mica granites. Late Palaeozoic igneous activity is sparse to absent in the central Appalachians.
In New England several kinds of mid-Devonian to Carboniferous igneous activity are represented. Biotite and biotite + muscovite granitoids dominate the central terranes, whereas the more easterly Avalon zone is intruded by alkalic-peralkalic plutonic rocks and contains minor bimodal volcanics. Final Permian plutonism includes intrusion of homogeneous metaluminous to peraluminous granite.
Within the Canadian Maritimes biotite and megacrystic granites followed by mildly alkalic varieties dominate the Devonian-Carboniferous plutons of New Brunswick and Newfoundland, whereas muscovite + biotite rocks are prominent in the Meguma terrane of Nova Scotia. Volcanism, which is bimodal, is best documented in New Brunswick and northern Nova Scotia. Igneous activity of Permian age is not recognized in the Canadian Maritimes.
The petrological diversity together with the considerable span of time represented by the late Palaeozoic igneous activity in the N American Appalachians indicates repeated and locally prolonged anatexis of a variety of heterogeneous crustal sources. The alkalic and bimodal suites are characteristic of extensional or anorogenic tectonics. The more aluminous rocks are generally compositionally similar to the Caledonian and, to a lesser extent, the Hercynian suites of Europe. Overall the igneous activity may reflect relatively independent rifting and accretion of small crustal plates of diverse thicknesses and compositions in which magmatism was not related to a simple subduction island-arc setting.
Late Palaeozoic metamorphism in the northwestern Iberian Peninsula, Brittany and related areas in SW Europe
Authors: Martínez Francisco J. , Rolet Joël 
Published: September 2007

Summary

In the NW of the Iberian Peninsula elongated and coalescent thermal domes are centred in P
3
antiforms and associated with granite plutonism. After the Emsian and before the Namurian, assemblages with garnet, staurolite and kyanite changed into others with andalusite-sillimanite, biotite and cordierite giving evidence of heating and/or decompression related to syn-metamorphic granite intrusion. The Namurian is roughly the metamorphic peak of low-pressure conditions in the inner zones. In the central Armorican domain in Brittany the main metamorphic event has an age between 330 and 345 Ma. There is also a pressure decrease with time and the earlier zones are telescoped in the W by subautochthonous leucogranites associated with high-grade zones. Contact aureoles affecting the Dinantian basins in Brittany must be late Carboniferous. In the other areas, i.e. Catalonia, the Pyrenees, Montagne Noire and the French Massif Central, the history is essentially the same, with the low-pressure metamorphic peak being Namuro-Westphalian.