bluuebunny/crossref_metadata_2025 huggingface dataset:
Lower Palaeozoic volcanism of northern Qilianshan, NW China
Authors: Zhang Zhijin
Published: April 2008

Thick volcanic sequences of mid-Cambrian-mid-Silurian age crop out in northern Qilianshan in NW China. Volcanism was concentrated in a marine basin almost 1000 km long situated at the SW margin of the N China-Korea paraplatform. The basin was subsequently deformed during Caledonian folding. Calc-alkaline, mildly alkaline and alkaline volcanic rock suites have been identified and a variety of ore deposits, genetically related to the volcanism, have been discovered.
Evidence for a Late Triassic-Early Jurassic orogenic event in the Taurides
Authors: Monod Olivier , Akay Ergün
Published: April 2008

A simple view of the Tethys during most of the Mesozoic emphasizes the contrast between the active northern European margin and the passive Southern Gondwanan margin which is considered to remain undeformed until the end of the Cretaceous. However, evidence from various places in the Taurus chain demonstrates the existence of a pre-Jurassic unconformity and a thrusting event. Indirect evidence is also provided by coarse, red oligomict clastic sediments (Çayır Formation) of Late Triassic to Lower Liassic age which are widespread on the older Tauride carbonate platform. A review of the data reveals a wide distribution of these sediments in southern Turkey, and their possible extension into the Hellenides (Chios). Finally, the evidence of Late Triassic to Early Jurassic deformation is considered in the light of recent syntheses of the evolution of the ‘Palaeotethys’.
Permian-early Mesozoic tectonism and continental margin formation in Israel and its implications for the history of the Eastern Mediterranean
Authors: Garfunkel Z. , Derin B.
Published: April 2008

The Early Mesozoic tectonic reorganization of the Tethys region also affected the Levant area. Here two processes were superimposed: (a) The pattern of long-wavelength vertical motions of the Arabo-Nubian platform changed in the Late Permian when Israel and nearby areas began to subside. (b) Rifting occurred in this subsiding area, probably in several phases: Late Anisian (and Ladinian?), Carnian-Norian, and Liassic. Differential movements reached 2–3 km and magmatism occurred in the Liassic and perhaps also in the Triassic. The tectonism was strongly felt up to 50 km landward of the present coast. The crust was thinned and modified under the present continental margin and in the main rifts. Passive margin conditions were established in Late Liassic times over the previously faulted area. Later in the Jurassic a carbonate shelf was constructed along this subsiding margin; its basinward edge was 1–1.5 km high, which shows that the adjacent SE Mediterranean was already a deep sea. Hence this basin and its passive margin are considered to have been shaped by the Early Mesozoic rifting which is recognized in Israel. The rifting process probably signifies oblique separation of the Tauride block from the Levant part of Gondwana.
Evidence for Early-Middle Triassic faulting and possible rifting from the Helez Deep Borehole in the coastal plain of Israel
Authors: Druckman Yehezkeel
Published: April 2008

A 600 m thick conglomerate, the Erez conglomerate, was penetrated in the Helez Deep borehole, drilled in the Coastal Plain of Israel. This conglomerate is underlain by a 40 m thick sandy shale of probable Early Triassic age, and is overlain by 190 m of Late Triassic peritidal dolomites. This sedimentary sequence is underlain by metamorphic Precambrian basement.

The Erez conglomerate is polymictic, consisting of various types of carbonate fragments, of ages varying from Upper Permian to Anisian. The fragments are angular to subrounded, poorly sorted, ranging in diameter from fractions of a millimetre to several decimetres. The matrix consists of black argillaceous micrite, yielding palynomorphs of Scythian-Anisian age.

It is suggested that the Erez Conglomerate is analogous to the thick, well-developed accumulation of polymictic conglomerates along the margins of the Miocene Suez and Plio-Pleistocene Dead Sea rifts, and thus indicating a major faulting phase and possibly an initial stage of rifting during Early-Middle Triassic times. Although an Upper Palaeozoic updoming prior to rifting may be considered, it is not a necessary postulate to explain the borehole data.
Role of the Eastern Mediterranean ophiolites (Turkey, Syria, Cyprus) in the history of the Neo-Tethys
Authors: Whitechurch Hubert , Juteau Thierry , Montigny Raymond
Published: April 2008

The internal organization and structure of the Taurus, Troodos, Hatay and Baër-Bassit ophiolite massifs are used, along with K-Ar geochronological data for the different parts of the assemblages, to outline stages in the evolution of the Neo-Tethys ocean during Mesozoic times. The authors distinguish:

(1)

an intra-continental stage, during Middle and Upper Triassic, when alkaline submarine basalts were erupted during rifting of the Arabian platform;

(2)

a Lower Cretaceous to Campanian phase, marked by active spreading for at least 40 Ma, along east-west trending palaeo-spreading axes, offset by north-south transform fracture zones. During that period, the oldest oceanic lithosphere (Tauride ophiolites and the Baër-Bassit complex) began to be sliced up with the development of metamorphic soles (104 to 88 Ma), later intruded by swarms of tholeiitic diabase dykes of Campanian age (ca. 75 Ma). At that time, the latest spreading zones, now represented by the Troodos and Hatay ophiolites, were still active in the Neo-Tethys; and

(3)

during the Maastrichtian (70–65 Ma), all ophiolitic massifs were thrust over the Arabo-African continental margin from a single Neo-Tethys oceanic basin.
Mylonitic ductile shear zones within tectonites and cumulates as evidence for an oceanic transform fault in the Antalya ophiolite, S.W. Turkey
Authors: Reuber Ingrid
Published: April 2008

In the coastal ophiolite belt of Antalya, especially in the massifs of Adrasan and Cıralı-Tekirova, tectonites and cumulates have preserved their primary structures. Tectonites display a first, high temperature-low deviatoric stress deformation S1, linked to the diapiric uplift of the asthenosphere below an east-west orientated spreading centre. A second mylonitic deformation produced under high deviatoric stress and lower temperature conditions produced shear zones of millimetric to kilometric scale throughout the tectonites and even in the cumulates. Their mean orientation (N 150 E) is near to perpendicular to the ridge axis, and the associated lineation indicates horizontal, essentially sinistral strike-slip displacement. This deformation must have taken place during the final crystallisation of the cumulates, as indicated by its relationship to intrusive gabbroic ‘dykelets’ representing residual liquids of the cumulates. The S2 deformation is attributed to a transform fault situated SW of the coastal complexes. Later tectonic events include thrusting and wrench faulting, again sinistral, in a north-south trending direction.
The Mesozoic organization of the Taurides: one or several ocean basins?
Authors: Ricou L. E. , Marcoux J. , Whitechurch H.
Published: April 2008

The Taurides are an Alpine chain composed of both continental and oceanic units including ophiolitic massifs organized in three longitudinal belts. The Taurides are also an area of nappes, where overthrusting occurred successively from the Upper Cretaceous on and greatly modified the pre-tectonic organization. A single or a multiple ocean basin system have both been postulated.

It is shown that the nappes composed of slope-basin material, ophiolites and their metamorphic soles vary from place to place in the Taurides. They exhibit a coherent organization which attests to a common origin with transport as a whole entity over the presently underlying platform units. The latter can not be continental slivers within the basin. The inferred large-scale allochthoneity is supported also by palaeontological and palaeomagnetic data, and by a consideration of the mechanisms of ocean-basin opening and obduction.

We concluded that the Tauride ophiolites, the associated slope-basin and horst deposits constitute a unique set of nappes derived from a single northern oceanic basin bordered to the south by a large epi-continental platform. This basin was located north of the platform units which now constitute the Calcareous Axis of the Taurides.
Tauric subduction (Malatya-Elazıǧ provinces) and its bearing on tectonics of the Tethyan realm in Turkey
Authors: Michard A. , Whitechurch H. , Ricou L. E. , Montigny R. , Yazgan E.
Published: April 2008

In the Eastern Taurus, The Elazıǧ nappes shown an ophiolitic association overlain by andesites and intruded by calc-alkalic granites, both of Late Cretaceous age. The basin was compressed in the Late Cretaceous between two metamorphic massifs each with a sialic basement and platform-type Permian to Mesozoic cover. This history indicates Late Cretaceous subduction under the Taurides and subsequent compression of the basin and arc.

Attempts to place this Tauric subduction in the geodynamic history of Turkey lead to conflicting interpretations and two alternative models are presented.

The first involves a single Tethyan ocean subducting northwards below the Pontides and southwards below the Taurides. The latter led to the Late Cretaceous opening of back-arc basins which split the formerly continuous Tauric-Arabian platform. Southward subduction ended when the ridge reached the trench, leading to compression of the Elazıǧ back-arc basin, southward obduction and closure of the ocean. The residual, Upper Cretaceous marginal basin controlled the subsequent Tertiary development of the area.

The second model involves a northern Tethyan ocean and a southern Mesogean ocean, both subducting northwards. Subduction of the southern ocean generated calc-alkaline magmatism and deformation of the leading edge of the Tauric blocks. The Elazıǧ basin closed as a result, having earlier formed either as a subduction-related marginal basin or as a pre-existing extensional basin. Southward obduction took place from both oceans. After closure of the Tethyan ocean, Tertiary development was controlled by reactivation of Mesogean subduction.
The Maden Complex, SE Turkey: evolution of a Neotethyan active margin
Authors: Aktaş G. , Robertson A. H. F.
Published: April 2008

In this paper we describe and interpret a critical segment of a Tethyan suture zone in SE Turkey dominated by a major nappe pile which, from the structural top downwards, consists of the following units: first, the
Elazıǧ-Palu nappe
, a major Upper Cretaceous volcanic arc complex and cover related to subduction of a southern strand of the Mesozoic Tethys. The arc rocks are regionally underlain by metamorphic rocks of the Bitlis-Pütürge nappe, but in the area studied this is absent and the next unit is the
Hazar-Guleman nappe
, which consists of a sliced ophiolitic assemblage of presumed Upper Cretaceous age unconformably overlain by a relatively undeformed succession of Palaeogene red beds (Ceffan Formation), flysch (Simaki Formation) and both pelagic and redeposited neritic limestones (Gehroz Formation). This nappe is cut by the
South Anatolian transform fault
. Below it the
Kıllan Imbricate Unit
consists of imbricated Upper Cretaceous ophiolitic and other mafic extrusives (Killan Group) associated with, and locally unconformably overlain by, Palaeocene and Eocene rocks ranging from deep sea sediments to sedimentary melange and detached blocks, with minor volcanics. Towards the sole-thrust the Killan Imbricate Unit is mostly tectonic melange. Below, are the autochthonous and para-autochthonous successions of the
Arabian foreland
, including ophiolitic olistostrome of latest Cretaceous age (Koçali Complex). Our Hazar-Guleman nappe and the Killan Imbricate Unit together constitute the
Maden Complex
. We also report on a distinctive assemblage of Middle Eocene mafic extrusives and interbedded deep water sediments further east along the suture zone (
Karadere Formation
), and briefly summarise implications for economic sulphide mineralization in the area.

We interpret the suture zone in terms of formation of a Mesozoic ocean basin followed by northward subduction. The Karadere Formation further east would in one possible model have formed by rifting of the fore-arc, possibly related to oblique convergence in the Middle Eocene. In an alternative model the Neo-Tethys had essentially closed by the latest Cretaceous facilitating ophiolite emplacement over both the northern active margin and the former passive southern margin. In this case the Killan Imbricate Unit would be related to tightening of the suture and the Karadere Formation to renewed rifting controlled by strike-slip faulting. In both models continental collision was well advanced by the Miocene with flysch and sedimentary melange deposition (Lice and Çüngüş Formations), followed by translation along the South Anatolian transform fault.
The Eastern Pontide volcano-sedimentary belt and associated massive sulphide deposits
Authors: Akıncı Ömer T.
Published: April 2008

The Eastern Pontide Belt is a major metallogenetic province in the Eastern Black Sea coastal region. Extensive volcanism was initiated in Liassic time. Palaeozoic granites and schists of older units form the ‘basement’. The overlying volcano-sedimentary units reach 7000 m in thickness as follows; Lower Basic Series, 195–88 Ma; Dacitic Series, 88–65 Ma; Upper Basic Series, 65–37 Ma; Tertiary Granitoids, 3772-22.5 Ma; Young Basic Series and Young Dykes.

The Lower Basic Series, cut by granodioritic intrusions, consists of basaltic and andesitic lavas, spilite, tuffs and agglomerates intercalated with limestones. The Dacitic Series consists mainly of andesitic, dacitic and rhyolitic lavas and pyroclastics alternating with mudstone, marly limestone and pelitic tuff. A major pillow lava flow divides the Dacitic Series into an ore-bearing lower and a less mineralized upper part. The Upper Basic Series is represented by extensive andesitic volcanism inland, while basaltic lavas and agglomerates occur along the coast. Syenite and quart-monzonites intrude this series. Granite, granodiorite, adamellite and monzonite intrusions form the Tertiary Granitoids. The youngest volcanism is represented by dykes and lavas. Radiometric ages of the intrusions show a continuity between Jurassic and Miocene, with increased activity around 80 and 40 Ma. The Lower Basic Series and the Dacitic Series are mainly tholeiitic; the Upper Basic Series and the other units are calc-alkaline.

More than 400 massive sulphide deposits are associated with tuffaceous horizons in the Dacitic Series of Upper Cretaceous age. These deposits show similarities with the Kuroko massive sulphide ores of Japan.
The role of the Ankara Melange in the development of Anatolia (Turkey)
Authors: Norman Teoman N.
Published: April 2008

The ‘Ankara Melange’, as defined by Bailey & McCallien (1953), comprises several belts, sub-belts and lenses of melange units, as well as some intercalated ocean floor fragments and continental (magmatic arc?, island arc?) slivers. Two significant observations are the successive younging of melange units from north to south (or northwest to southeast locally) and mega-debris flow features in some of melange units indicating a possible flow direction from east to west (or northeast to southwest). Both observations can be explained by assuming an obliquely northward moving Tethys ocean plate, subducting under a continental mass against which successive accretion and obduction of ocean floor irregularities (such as ocean plateaux, ridges, magmatic island arcs or even continental slivers) from Early Jurassic times to Middle Oligocene, produced the present complex melange system. Flow features can be explained by the development of local high ground where a non-subducting oceanic platform transpressed obliquely against the already-formed melange material, causing it to flow successively to depressed (trench) regions. Such flows were naturally interbedded with, or accompanied by, other types of mass flows and slivers of continental and/or oceanfloor material.
Distribution and characteristics of the north-west Turkish blueschists
Authors: Okay A. I.
Published: April 2008

North-west Turkey encompasses two major tectonic units, the Pontides and the Anatolides, separated by the İzmir-Erzincan suture. The Anatolides, the metamorphosed northern extension of the Taurides, consist of several zones. The more southerly Afyon Zone is an Early Palaeozoic to Maastrichtian Tauride shelf-type sequence which rests on gneisses of the Menderes Massif. The Afyon Zone underwent greenschist facies metamorphism, gradually increasing in grade with depth, and overthrust by HP/LT metamorphic rocks and peridotites. A HP/LT metamorphic belt several hundred kilometres long constitutes the second Anatolide zone. There are two tectonic units in the blueschist sequence. A lower more recrystallised blueschist unit consists of a thick basal marble series overlain by meta-cherts, metabasites and meta-shales. An upper unit, with a wider distribution, shows only incipient HP/LT metamorphism, and consists of shales, radiolarian cherts, basic volcanic rocks, pelagic limestones and greywackes. The HP/LT rocks are tectonically overlain by a peridotite nappe, without HP/LT metamorphism. Steeply dipping major faults separate blueschists from the Inner Pontide sequence, which consists of a Permian-Triassic metamorphic basement overlain by carbonates and Upper Cretaceous flysch. Especially in the Ankara region, Upper Cretaceous flysch contains abundant ophiolitic olistoliths. Post-orogenic Palaeocene sediments are transgressive over the HP/LT metamorphic belt and the peridotite nappe. The blueschist sequence may have been the north-facing Anatolide/Tauride platform margin, subducted during the Late Cretaceous. Very fast uplift in the collision zone, aided by buoyancy of subducted continental crust, generated olistostromes in the Pontides and emplaced peridotite nappes over the Anatolide/Tauride platform.
Palaeotectonic evolution of the Tuzgölü basin complex, Central Turkey: sedimentary record of a Neo-Tethyan closure
Authors: Görür N. , Oktay F.Y. , Seymen İ. , Şengör A. M. C.
Published: April 2008

The Tuzgölü basin complex represents a cluster of epi-sutural depressions nested on the Ankara Knot in central Anatolia, where several sutures converge. The basin complex consists mainly of two sub-basins, the Haymana and the Tuzgölü (
s.s.
) depressions. During the Late Cretaceous to the Late Palaeocene, the Tuzgölü and the Haymana sub-basins evolved coevally, but independently, as fore-arc basins along the active margins of the Sakarya Continent and the Kırşehir block. Turbidites accumulated in the basin interiors, with shallow marine and terrestrial deposition near the basin margins. Late Palaeocene-Early Eocene collision of the Menderes-Taurus block with the Sakarya Continent and the Kırşehir block along the Inner Tauride Sture, and the coeval collision of the Kırşehir block with the Rhodope-Pontide Fragment along the Erzincan suture juxtaposed and deformed the two sub-basins. Intra-continental convergence continued during the Early to Middle Eocene with further subsidence and turbidite deposition in both sub-basins. After the Middle Eocene, a single molasse basin was characterized by extensive redbeds and evaporites. Extensive salt deposits in the Tuzgölü sub-basin probably relate to marine regression in the later Eocene. The present Tuzgölü basin is part of neotectonic Turkey and constitutes one of the large central Anatolian
ovas
.
High-pressure rocks of Samos, Greece
Authors: Okrusch M. , Richter P. , Katsikatsos G.
Published: April 2008

The metamorphic complex of Samos is composed mainly of marbles and phyllites, typically with intercalations of serpentinites, meta-gabbros, blueschists, and greenschists.

The meta-gabbros show typical flaser-structures, but contain frequent textural relics of the igneous protolith as well as relict clinopyroxene and brown hornblende. Primary plagioclase is totally replaced by albite, epidote or zoisite. Critical mineral assemblages of the Alpidic metamorphism are:

albite + epidote + chlorite + glaucophane ± barroisite + sphene,

albite + epidote + zoisite + tremolite + muscovite + sphene,

albite + epidote + chlorite + tremolite ± barroisite ± muscovite ± calcite ± sphene.

Associated glaucophanites show the following critical assemblages (+ sphene ± rutile):

garnet + glaucophane + epidote ± barroisite + chlorite + muscovite ± paragonite,

glaucophane + epidote + chlorite + muscovite + albite ± quartz.

The major and trace element chemistry confirms that the metabasites are derived from abyssal tholeiites and related gabbros.

The metapelites of Samos frequently contain chloritoid which, in the eastern part of the island, may be accompanied by kyanite, and rarely by Mg-carpholite. Meta-bauxites in eastern Samos contain diaspore, in western Samos diaspore + corundum (Mposkos 1978).

At the peak of metamorphism temperatures may have reached about 420° and 470°C in east and in west Samos respectively, assuming elevated pressures of about 8 kbar.
Origins and significance of rocks in an imbricate thrust zone beneath the Pindos ophiolite, northwestern Greece
Authors: Kemp Alan E. S. , McCaig Andrew M.
Published: April 2008

Major zones of imbrication under the Pindos ophiolite of northwestern Greece relate to the formation of frontal and oblique ramp structures. These are marked by a northwest-trending line of tectonic windows in the ophiolite and a northeast-trending anticlinal structure which folds thrust contacts. The simplified structural sequence from top to bottom is:

(1)

Ophiolite lithologies, mainly pillow basalts and basal serpentinite;

(2)

Metabasites and meta-sediments of the ophiolite dynamothermal aureole ranging up to lower amphibolite facies;

(3)

A complex sequence of basalt, gabbro, pelagic sediments, olistostromes, debris flows and breccias interpreted as a sea floor sequence (the Perivoli Complex);

(4)

Early Cretaceous calcareous flyschoid sediments; and

(5)

Tertiary Pindos Flysch and melange.

All the greenschist facies and the higher grade metamorphic rocks are interpreted as part of the metamorphic aureole and not as Palaeozoic basement. The generalized sequence of major deformational episodes is:

(A)

Thrusting within the sea floor with concurrent metamorphism causing polyphase deformation and juxtaposition of the ophiolite, the dynamothermal aureole and the Perivoli Complex.

(B)

The main imbrication along NNW-trending, E-dipping planes, involving all the lithologies and associated with the formation of major frontal and oblique ramp structures. (A) occurred during the Middle Jurassic ‘displacement’ of the ophiolite sheet. ‘Emplacement’-related deformation may have occurred in (1), (2) and (3), but is difficult to isolate due to the intensity of episode (B) which occurred during westward overthrusting in the Late-Tertiary and may have been related to an E-dipping subduction zone.
Age constraints on the igneous and metamorphic evolution of the Hellenic-Dinaric ophiolites
Authors: Spray J. G. , Bébien J. , Rex D. C. , Roddick J. C.
Published: April 2008

The available age data from Greek and Yugoslavian ophiolites and related rocks are reviewed and, where necessary, have been corrected using the decay constants of Steiger & Jäger (1977). In addition, new K-Ar ages are presented from igneous mineral phases from the Guevgueli ophiolite and Fanos granitoid. Rb-Sr ages are also presented for the Furka and Stip granitoids of the Vardar Zone. Igneous ages of the dated ophiolites are approximately 160–180 Ma, although data from the Guevgueli Complex indicate that associated basic igneous activity also occurred during the Upper Jurassic. Granitoids yield ages ranging between 150 to 174 Ma. When compared with dates obtained from metamorphic soles beneath the Greek and Yugoslavian ophiolties (160–180 Ma), it is apparent that both sub-ophiolite metamorphism and granitoid intrusion closely followed ophiolite formation at a spreading centre. This indicates that the initial obduction movements occurred when the ophiolites were both young and hot and capable of forming basal dynamothermal soles mainly by the effects of their residual heat. When these ages are integrated with the field evidence for the period of final ophiolite emplacement in the Hellenides and Dinarides (Late Jurassic to Early Cretaceous), it is possible to reconstruct a simplified igneous, metamorphic and emplacement history for these displaced fragments of oceanic crust and upper mantle.
Tectonic implications of palaeomagnetic results for the Carpatho-Balkan and adjacent areas
Authors: Márton Emö
Published: April 2008

From palaeomagnetic results, two different tectonic units can be recognized in the Carpatho-Balkan region and adjacent areas.

The north-western unit comprises the Italian peninsula south of the Po-basin, Sardinia, the Istria peninsula of Yugoslavia, the Transdanubian Central Mountains and the Bükk Mountains in Hungary and the outer and inner West Carpathians of Czechoslovakia. The palaeomagnetic results suggest that this unit was part of the African plate in the Mesozoic and Palaeogene, but was later decoupled from Africa.

The south-eastern unit is not very well defined palaeomagnetically. Palaeopoles are known from the Mecsek and Villány Mountains in Hungary, and the Papuk Mountains of Yugoslavia and North-West Bulgaria. They are similar to the poles of the same age from stable Europe but do not yet provide a coherent pattern. The palaeomagnetic results to date clearly testify to a different rotational history of this unit from the history of the African plate and the north-western unit, but more extensive palaeomagnetic studies especially on post-Palaeozoic rocks are needed to reveal the details of the movement history.
Paleogeography and palinspastic reconstruction of the Neogene of the Mediterranean and Paratethys
Authors: Steininger Fritz F. , Rögl Fred
Published: April 2008

Eight palaeogeographic-palinspastic sketches are presented for intervals from Late Oligocene to Pliocene times for the circum-Mediterranean area and the Paratethys. They are based primarily on accurate correlation of marine and continental biogeographic events and take into account the generally accepted ideas of plate tectonics. The marine and continental connections that can be inferred contribute important information on the geological evolution of the Eastern Mediterranean.
Palaeomagnetic data from Tertiary units of the north Aegean zone
Authors: Kondopoulou D. , Lauer J. P.
Published: April 2008

New palaeomagnetic data from the north Aegean area show that in this region an overall clockwise rotation is likely to have taken place in the late Tertiary.
Tectonic evolution of the North Aegean trough
Authors: Lybéris Nicolas
Published: April 2008

Geological field data are used together with interpretation of Landsat images, results obtained during a
Jean Charcot
cruise in 1972, and other available seismic reflection profiles, to discuss the tectonic evolution of the North Aegean trough. This bathymetric trough is located over a narrow sedimentary basin with up to 6 km of sediment connected to two NNW-SSE sedimentary basins: the Thermaïkos and Kavala basins. The prevailing tectonic regime is extensional associated with strike-slip, with no evidence of compression as confirmed by seismo-tectonic observations. This regime has dominated the evolution of the North Aegean, as the prolongation of the North Anatolian fault since the Tortonian, However, the present eastern bathymetric trough does not have the same tectonic origin. The main extensional zone apparently lies to the north of it and continues eastward into the Thrace basin up to the Maritsa fault.
Rotational mechanisms of active deformation in Greece and Iran
Authors: Jackson James , McKenzie Dan
Published: April 2008

The purpose of this paper is to emphasize the importance of vertical and horizontal rotations in the evolution of geological structures. In the Aegean region pervasive normal faulting, probably listric in nature, is responsible for substantial vertical rotation of footwall and hanging wall blocks as well as fault planes. The experience of the Basin and Range Province suggests that strain fields deduced from micro- or macro-structural analyses of fault planes in such an environment are unlikely to be correct unless the detailed 3-dimensional geometry of the motion on the largest faults is known. A particular hazard is the interpretation of rotated low angle gravity glides and high angle antithetic normal faults as thrusts and reverse faults respectively.

In northeast Iran, a combination of thrust and strike slip faulting has led to substantial horizontal rotations whose sense can only be deduced by a knowledge of the history of movement on major structures or by palaeomagnetism. In zones of major continental deformation present day strike azimuths, as well as horizontal and vertical directions, are of no particular significance, and the interpretation of even quite young structural data without a knowledge of the rotations involved may lead to incorrect geological reconstructions.
Listric normal faulting and the reconstruction of the synmetamorphic structural pile of the Cyclades
Authors: Ridley John
Published: April 2008

There are late, post-metamorphic faults on the Aegean island of Syros that are demonstrably listric normal. Breccias associated with these faults are identical to those of late low-angle faults elsewhere on the island. It is therefore proposed that these low-angle faults are the toes of listric normal faults. This provides a basis for delineating a structural succession prior to faulting in which apparently ‘allochthonous’ rocks were originally at a higher level in the pile. This is consistent with the observed structural succession on Syros. The highest structural units are greenschists with similar kinematic axes to those of the blueschists below, but with a contrasting deformation style. These greenschists may have been derived from the ‘roof’ of the convergence zone in which the blueschist metamorphism took place.

Similar fault patterns can be inferred for many of the neighbouring islands, which are horst blocks. Many show peripheral ‘upper units’ of weakly- or non-metamorphic rocks. The ‘upper units’ are inferred to have been originally at a high level in a pile built up during early Tertiary tectonism and are not remnants of a far-travelled nappe emplaced in the Miocene.
On the Neogene development of the Eastern Mediterranean basins
Authors: Jasko S.
Published: April 2008

The cauldron-like depressions of the Eastern Mediterranean, the Black Sea and the Southern Caspian differ from the foredeep basins of young fold-mountains of Neotectonic Europe in shape and form. The formation of these collapse structures has modified the palaeogeography of the Alpine-Carpathian-Balkan-Caucasus mountain system.

The deep basins of the Mediterranean formed in the south of Neotectonic Europe and on the margins of North Africa, probably at the beginning of the Pliocene. Subsidence of the Black Sea and of the Southern Caspian took place in the north of Neotectonic Europe and on the margin of the Russian platform in the Late Pliocene and Early Quarternary.
A Middle Miocene thermal event in northern Greece confirmed by coalification measurements
Authors: Chiotis E. D.
Published: April 2008

An important thermal event is confirmed by vitrinite reflectivity measurements on coal samples from deep oil exploration wells in Kavala Bay and the Nestos delta, northern Greece. Only the lower depositional sequence of the Nestos Delta, to which a Middle Miocene age is attributed, has been affected. The coal bearing sediments have been heated to temperatures above 200°C at depths less than 2000 m. A plutonic intrusion east of the Nestos wells is postulated to have been the cause. The event corresponds in time to the well known episode of Middle Miocene local anatexis and acid plutonism in the central and southern Aegean area.
Loose-boundary hydraulics and fluid mechanics: selected advances since 1961
Authors: Allen J. R. L.
Published: April 2008

A major and acknowledged role in the advance of sedimentological knowledge is played by the methods of physics as expressed through fluid mechanics and loose-boundary hydraulics. Turbulence is increasingly being seen as involving orderly flow structures, and these are significant for the origin of several sedimentary structures and for suspension transport. Recent advances in sediment-transport theory are rooted in the concept of the sediment load as a downward-acting force and in the notion of the flow as a transporting machine. Laboratory experiments are increasing our understanding of bedforms due to rivers and waves, but there is a need for well-framed field studies to clarify the influence of change in natural environments. Physical explanations are being proposed for tidal bedforms. Field studies in both modern environments and the stratigraphic record suggest that tidal patterns and strengths are recognizable from the internal features of cross-bedded units formed by sand waves. Tidal patterns are complex, however, and a wider range of situations needs to be explored than has hitherto been the case. Mathematical modelling could help to define the expectable bedding patterns. Although successful mathematical models have been constructed of flow and sedimentation in channel bends, secondary flow in real bends and the evolution of those bends are not yet well understood. Turbidity currents on a geologically significant scale have not been observed directly, but valuable insights into their character and processes have come from laboratory experiments. Recent laboratory work points to the limitations of lock-exchange experiments and emphasizes the various ways in which turbidity currents mix with the ambient medium. These studies seem to have implications, yet to be worked out, for the internal features and some sole marks of turbidites.
Facies analysis of volcaniclastic sediments: a review
Authors: Suthren R. J.
Published: April 2008

A number of problems are encountered in the study and interpretation of sequences of volcaniclastics (sediments or sedimentary rocks composed predominantly of volcanic particles). These problems include the lack of modern analogues, the complex interaction of volcanic and sedimentary processes, and extensive diagenetic alteration. Volcaniclastic sediments are produced and emplaced by
autoclastic
(mechanical breakage during magma movement),
hydroclastic
(water/magma interaction),
pyroclastic
(magmatic explosion) and
epiclastic
(sedimentary erosion, transport and deposition) processes, or by any combination of these. The systematic study of lithology, texture and primary structure sequences, and their lateral and vertical variations, is leading to the erection of facies models for recent volcaniclastics. These models are likely to have important applications in the interpretation of ancient sequences of volcaniclastic sedimentary rocks, as well as practical applications in mineral and petroleum exploration and volcano prediction.
Shortening of continental lithosphere: the neotectonics of Eastern Anatolia — a young collision zone
Authors: Dewey J.F. , Hempton M.R. , Kidd W.S.F. , Saroglu F. , Şengör A.M.C.
Published: April 2008

We use the tectonics of Eastern Anatolia to exemplify many of the different aspects of collision tectonics, namely the formation of plateaux, thrust belts, foreland flexures, widespread foreland/hinterland deformation zones and orogenic collapse/distension zones. Eastern Anatolia is a 2 km high plateau bounded to the S by the southward-verging Bitlis Thrust Zone and to the N by the Pontide/Minor Caucasus Zone. It has developed as the surface expression of a zone of progressively thickening crust beginning about 12 Ma in the medial Miocene and has resulted from the squeezing and shortening of Eastern Anatolia between the Arabian and European Plates following the Serravallian demise of the last oceanic or quasioceanic tract between Arabia and Eurasia. Thickening of the crust to about 52 km has been accompanied by major strike-slip faulting on the right-lateral N Anatolian Transform Fault (NATF) and the left-lateral E Anatolian Transform Fault (EATF) which approximately bound an Anatolian Wedge that is being driven westwards to override the oceanic lithosphere of the Mediterranean along subduction zones from Cephalonia to Crete, and Rhodes to Cyprus. This neotectonic regime began about 12 Ma in Late Serravallian times with uplift from wide-spread littoral/neritic marine conditions to open seasonal wooded savanna with colluvial, fluvial and limnic environments, and the deposition of the thick Tortonian Kythrean Flysch in the Eastern Mediterranean. Earthquake hypocentres are scattered throughout the region but large earthquakes are concentrated mainly on the major faults and are mostly shallow, supporting the idea of a brittle elastic lid with hypocentres concentrated towards its base with more ductile deformation in the middle and lower crust. Neotectonic magmatic suites are nepheline-hypersthene normative alkali basalts of mantle origin, and silicic/intermediate/mafic calcalkaline suites, both suites occurring in pull-apart basins in strike-slip regimes and along N-S extensional fissures, and both suites showing a strong change to central activity in the Pliocene. Upper-crustal strains appear to be discontinuous in space and time, with zones of strong shortening representing shoaling of crustal detachment zones flattening between 5 and 10 km. Approximately NW- (dextral) and NE- (sinistral) trending lineaments bound less deformed wedges (low relief seismically ‘dead’ areas) and vary from simple strike-slip faults to complicated braided transform-flake boundaries with pull-apart and compressional segments (N and E Anatolian Transform Faults). Volcanoes lie in grabens on N-S ‘cracks’ that extend into the Arabian Foreland and in transcurrent pull-aparts. Major extensional basins lie at plate (Adana) and flake (Karliova) triple junctions and result from compatibility problems.
Garnet, tourmaline and muscovite-bearing leucogranites, gneisses and migmatites of the Higher Himalayas from Zanskar, Kulu, Lahoul and Kashmir
Authors: Searle M. P. , Fryer B. J.
Published: April 2008

Approximately 30–50% of the map area of the Central Crystalline Complex of the Higher Himalayas in Zanskar, Kulu, Lahoul and Kishtwar-Kashmir (NW India) is composed of Miocene leucogranites intruding metamorphic basement rocks. Ultrametamorphism at deeper crustal levels resulted in
in situ
anatexis, migmitization and
lit-par-lit
intrusions or stromatic layering within high-grade metasedimentary rocks. Garnet, tourmaline and muscovite-bearing granites locally contain biotite, apatite or kyanite.

Leucogranites at higher crustal levels are associated with a widespread network of anastomosing dykes and sills with high tourmaline content. Rare-earth-element (REE) abundances are relatively low. Garnets are compositionally variable and are usually unzoned.

Extremely high
87
Sr/
86
Sr initial ratios of leucogranites (0.755–0.769) indicate a crustal anatectic origin while the wide range of Sr initial ratios can be explained by melting of a variety of metasedimentary rocks of the subducting Indian Shield.

Radiometric ages of Himalayan leucogranites (28–12 Ma) follow closely in time a thermal peak of metamorphism (40–25 Ma). Inversion of metamorphic isograds during large-scale crustal subduction along several major thrust zones in the Higher Himalayas followed immediately after generation of the leucogranites. The leucogranites are interpreted as anatectic melts of high-grade metamorphic crystalline basement, generated at depth by residual (Barrovian) heat with a large amount of volatile and fluid flux. Frictional heating along the N-dipping Main Central Thrust is not considered a major source of heat for generation of the leucogranites.
The Alps: a case of multiple collision
Authors: Hunziker J. C.
Published: April 2008

The numerous isotopic data accumulated during the last decade throughout the Western Alps, make it tempting to draw a picture of polyphase Alpine tectono-metamorphic history constrained by these data. Gabbroic precursors of the Mesozoic Piémont ophiolites in the Dent Blanche Nappe, point to a thinning of the continental crust by the beginning of the Triassic. Biotite cooling ages of ∼ 180 Ma, in the Valpelline-IIDK-Ivrea Unit, set an older limit to the beginning of Alpine nappe emplacement. The younger limit is given by Cretaceous ages on high-pressure paragenesis in the Sesia basement and the Piémont ophiolites. In both, this first eo-Alpine tectono-metamorphic cycle was overprinted by an Eocene-Oligocene greenschist-facies metamorphism and a recumbent schistosity. Miocene mica cooling ages, as well as apatite fission track ages, can be linked to the Miocene décollement and ‘rétrocharriage’ phase in the Western Alps, followed by isostatic re-equilibration and denudation.
The NW external Alpine Thrust Belt and its implications for the geometry of the Western Alpine Orogen
Authors: Butler R. W. H. , Matthews S. J. , Parish M.
Published: April 2008

The NW external Alpine Thrust Belt contains an imbricated basement—cover sequence which is broadly continuous with the French cratonic foreland. This thrust belt developed in the late stages of Alpine orogenesis and carried the previously deformed and metamorphosed internal zones to the WNW, piggy-back fashion, onto the French Craton. Balanced cross-sections restore the thrust-belt structures to lie for over 100 km to the ESE of their present, innermost outcrop trace. The regional sole thrust commonly lies in the upper crust. To acheive a balance between different crustal levels requires a layer of lower crust, on which the external zones originally lay, to underlie the entire present outcrop width of the Alps. Therefore models of Alpine orogenesis, which require the internal zones to be underlain by their deep crustal root, are not valid and new models are required to explain the sub-surface geometry of the NW Alps. This paper stresses the importance of resolving the external parts of orogens, particularly using balanced cross-sections, before attempting to either interpret the internal parts of orogenic belts or make palaeogeographical reconstructions.
Palaeomagnetism and continental collision in the Alpine Belt and the formation of late-tectonic extensional basins
Authors: Channell James E. T.
Published: April 2008

New palaeomagnetic data are consistent with the hypothesis that Adria moved as a promontory of the African Plate during the Mesozoic. This hypothesis is supported by regional facies analysis and by geophysical data from the eastern Mediterranean basins which indicate a continental lithosphere. However, the new data cast doubt upon the concept of a rigid, autochthonous African promontory remaining coherent during Alpine deformation. It is apparent that small-scale relative rotations have occurred during the Tertiary in areas which were previously considered authochtonous. Late-tectonic extensional basins, such as the Tyrrhenian Sea, are superimposed on the continent-continent collision suture and their growth is contemporaneous with thrusting in surrounding arcs. The very rapid evolution of the collision suture into a region of extension is due to a rapid lithospheric thinning process, such as catastrophic delamination of part of the mantle lithosphere. Such delamination would be most likely to occur very soon after a collision involving fast lithospheric thickening.
Collision tectonics in the Scandinavian Caledonides
Authors: Hossack J. R. , Cooper M. A.
Published: April 2008

The Scandinavian Caledonides provide a well-exposed example of a deeply eroded orogen. The pre-erosion thrust front is located much farther to the E than previously supposed, the only true autochthon being S of Oslo. The external zone of the orogen is divided into three series of thrust sheets; the Baltic Cover Sheets, the Crystalline Thrust Sheets and the Oceanic Thrust Sheets. The three thrust sheet complexes are derived from widely different provenances but display all the characteristics of a classic fold and thrust belt. Sections through the external zone can be balanced and restored, indicating large amounts of translation southeastwards onto the Baltic Craton. The internal zone is composed of a number of tectonostratigraphic disparate units which display a ductile style of deformation. Sections through the internal zone are not restorable and assemblage in a large-scale shear zone is proposed, followed by thrusting onto the Baltic Craton. Deformation in the orogen occurred throughout a period of ∼ 100 Ma starting in the Late Cambrian. Thrust vectors for the orogen display rotation with time and are generally oblique to the Caledonian Front; within the internal zone stretching lineations are parallel to orogenic strike. A collision model for the orogen includes two W-dipping subduction zones, oblique collision producing shear parallel to the orogen and oblique thrust-sheet motions culminating in the large-scale underthrusting of the Laurentian Craton by the Baltic Craton.
On the anisograptid affiliation of
‘Dictyonema’ flabelliforme
(Eichwald 1840) and its nomenclatural consequences
Authors: Erdtmann Bernd-Dietrich
Published: April 2008

The recent discovery of
Radiograptus
stratigraphically below a series of morphological predecessors to the planktic siculate
‘Dictyonema’ flabelliforme-sociale
groups suggests a phyletic derivation of these forms from the anisograptid
Radiograptus
(Bulman 1950) and thus requires a taxonomic revision of the planktic species of
Dictyonema
. The type species of
Dictyonema, D. retiforme
(Hall 1843), is a Silurian sessile benthic member of the family Dendrograptidae. The genus
Dictyonema
must be restricted to represent the approximately 140 sessile species of cone-shaped, dissepimentous, dendroid graptolites (upper Cambrian-Carboniferous), whereas the homeomorphic planktic forms, now belonging to the family Anisograptidae, require a new generic name. The names
Rhabdinopora
(Eichwald 1855),
Graptopora
(Salter 1858) and
Dictyograptus
(Hopkinson & Lapworth 1875) are valid
nomina oblita
for this group of graptolites, with
Rhabdinopora
having priority.
Dictyograptus
would be a much favoured alternative name because of its long historical application to the ‘
flabelliforme-sociale
group’ and its euphonic semblance to
Dictyonema
, but being a junior name, its preference over
Rhabdinopora
would require suppression of the rule of Priority and is not recommended. The history of the generic status of
Rhabdinopora flabelliformis
(Eichwald 1840) and of
R. socialis
(Salter 1858) is briefly reviewed.
Biostratigraphic integration of Ordovician graptolite and conodont zones—a regional review
Authors: Bergström Stig M.
Published: April 2008

Graptolite and conodont zonal successions, each currently including about fifteen zones, serve as the principal bases for regional correlations within the Ordovician System. Zonal graptolites and conodonts are not commonly found together but recent work in Baltoscandia, North America, and other areas has made it possible to establish more than eighty levels of ties between graptolite and conodont zonal units. Most of these are in strata of Arenig, Llanvirn, and Llandeilo age; relatively fewer ties have been found in other parts of the system. A regional evaluation of graptolite/conodont zone relations has produced useful new information not only about correlation between standard graptolite and conodont zones, but also, indirectly, about relations between units in the graptolite-zone successions of the European and Pacific Provinces.