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In the mid-1850s, Thomas Henry Huxley, who coined the term 'coccolith', described their presence in oceanic sediments dredged from the sea floor. Subsequent recognition of their occurrence in the Upper Cretaceous English Chalk, largely unconsolidated pelagic sediment, and similar, more lithified limestones in the Jurassic of the Alps, led to their being considered major rock-forming elements through much of geological time, although they are now known to be limited to the Late Triassic–Recent interval. Unlike Charles Darwin, who did not travel abroad following the voyage of the Beagle, Huxley made a number of trips to Italy and Switzerland and is recorded as a guest in the exclusive Hotel Kursaal Maloja in the Engadin in 1893. While staying there, he made a number of excursions on foot and his presence was thought significant enough that it is recorded in an inscribed granitic stone tablet, erected in 1896, describing him as'the illustrious writer and naturalist'. His rambles would have led him past outcrops of tectonically emplaced true oceanic calcareous sediment of Early Cretaceous age, here shown to have originally contained coccoliths that were largely destroyed under the imprint of Alpine metamorphism of sub-greenschist to greenschist facies. To this extent, Huxley could have come close to recognizing true oceanic sediments exposed on land, but the dissimilarity between these Swiss Alpine deposits and the friable English Chalk would not obviously have led to the investigation of the former for the organisms he had christened as 'coccoliths'. [ABSTRACT FROM AUTHOR]

In 1890, former students of Arnold Guyot at the University of Neuchàtel dedicated a 'large glacial boulder from Neuchâtel' to his memory, now in front of Guyot Hall at Princeton University. We established that this block originated with all certainty from Upper Carboniferous conglomerates of the Salvan–Dorénaz Basin, the relics of which crop out in the Alps of western Switzerland and eastern France. During the Last Glacial Maximum, the boulder travelled from the lower Rhône Valley on the back of the Pleistocene Rhône Glacier to Neuchâtel from where, later, it crossed the Atlantic and was transported to Princeton. Guyot's name is familiar to geologists because of the term 'guyot', introduced 1946 by Harry Hess for 'curious flat-topped peaks scattered over millions of square miles in the Pacific basin', many of which are now known to represent drowned carbonate platforms. [ABSTRACT FROM AUTHOR]

Tectono-sedimentary breccias, known as ophicalcites, overlie serpentinised peridotites at a Jurassic ocean–continent transition along the Penninic-Austroalpine transition in the Eastern Alps of Switzerland. Deformation of the exhumed mantle rocks and breccia formation occurred under decreasing temperatures and along low-angle detachment faults exposing the mantle rocks at the sea floor and was coupled with hydrothermal activity and carbonation of the serpentinites at shallow depth and/or at the sea floor. Carbon isotopes in the ophicalcites persistently show marine values; however, the interpretation of oxygen-isotope values remained controversial: are they related to Jurassic hydrothermal activity or do they reflect Alpine metamorphic overprint? Here we discuss recent interpretations that relate oxygen isotope values measured in ophicalcites exclusively to Jurassic hydrothermal activity; to this end we use data that we earlier obtained along a north–south profile across Graubünden (eastern Switzerland). We revisited the sites of controversial interpretation along a north–south profile in eastern Switzerland. Along this profile, oxygen isotope values in ophicalcites and overlying pelagic sediments, up to 25 my younger than the ophicalcites, show identical values and become systematically lower with increasing Alpine metamorphism; they strongly deviate from values in ophicalcites and pelagic sediments measured along the Mid-Atlantic Ridge or ancient Atlantic ocean-continent transitions as e.g. in the Iberia–Newfoundland transect. The oxygen-isotope values measured in Alpine ophicarbonates thus reflect isotopic resetting during the Alpine orogeny, related to fluid-rock interaction during regional metamorphism. Hydrothermal processes that accompanied the formation of ophicalcites are not disputed; however, they cannot be traced by oxygen isotope geochemistry. [ABSTRACT FROM AUTHOR]

They do not reflect the temperatures of carbonation of the serpentine host rocks or the formation of calcite in veins and cements or of marine biogenic calcite in pelagic sediments associated with the ophicalcites. However, at other localities like Arosa, the ophicalcites co-occur with basalts, similar to the ophicalcites at Falotta (Platta Nappe). 4), with the oxygen isotope values from Marmorera-Cotschens (Coltat et al. [4]) added Coltat et al. ([5]) distinguish between "cooler ophicalcites" in the South-Penninic nappes and the ophicalcites of the Platta Nappe. [Extracted from the article]

The Upper Cretaceous (Campanian–Maastrichtian) bioclastic wedge of the Orfento Formation in the Montagna della Maiella, Italy, is compared to newly discovered contourite drifts in the Maldives. Like the drift deposits in the Maldives, the Orfento Formation fills a channel and builds a Miocene delta‐shaped and mounded sedimentary body in the basin that is similar in size to the approximately 350 km2 large coarse‐grained bioclastic Miocene delta drifts in the Maldives. The composition of the bioclastic wedge of the Orfento Formation is also exclusively bioclastic debris sourced from the shallow‐water areas and reworked clasts of the Orfento Formation itself. In the near mud‐free succession, age‐diagnostic fossils are sparse. The depositional textures vary from wackestone to float‐rudstone and breccia/conglomerates, but rocks with grainstone and rudstone textures are the most common facies. In the channel, lensoid convex‐upward breccias, cross‐cutting channelized beds and thick grainstone lobes with abundant scours indicate alternating erosion and deposition from a high‐energy current. In the basin, the mounded sedimentary body contains lobes with a divergent progradational geometry. The lobes are built by decametre thick composite megabeds consisting of sigmoidal clinoforms that typically have a channelized topset, a grainy foreset and a fine‐grained bottomset with abundant irregular angular clasts. Up to 30 m thick channels filled with intraformational breccias and coarse grainstones pinch out downslope between the megabeds. In the distal portion of the wedge, stacked grainstone beds with foresets and reworked intraclasts document continuous sediment reworking and migration. The bioclastic wedge of the Orfento Formation has been variously interpreted as a succession of sea‐level controlled slope deposits, a shoaling shoreface complex, or a carbonate tidal delta. Current‐controlled delta drifts in the Maldives, however, offer a new interpretation because of their similarity in architecture and composition. These similarities include: (i) a feeder channel opening into the basin; (ii) an excavation moat at the exit of the channel; (iii) an overall mounded geometry with an apex that is in shallower water depth than the source channel; (iv) progradation of stacked lobes; (v) channels that pinch out in a basinward direction; and (vi) smaller channelized intervals that are arranged in a radial pattern. As a result, the Upper Cretaceous (Campanian–Maastrichtian) bioclastic wedge of the Orfento Formation in the Montagna della Maiella, Italy, is here interpreted as a carbonate delta drift. [ABSTRACT FROM AUTHOR]

Surface mechanical attrition treatment (SMAT) is a powerful and practical method to surface-harden metals and alloys through the generation of a gradient nanostructured surface. In this study 304 stainless steel was SMAT processed and the mechanical response upon repeated frictional sliding is studied as well as compared to the mechanical response of untreated as-received 304 stainless steel. The repeated frictional sliding experimental work is complemented by finite-element analysis in order to quantify the stress and strain distribution and to qualitatively determine the elastic-plastic deformation behavior. It is shown that repeated frictional sliding on the SMAT processed 304 stainless steel surface results in smaller residual depth, pile-up height and friction coefficient but higher maximum stresses compared to the as-received 304 stainless steel. After approximately 30 cycles the residual depth increases only minimally with each additional cycle because of strain hardening and increased contact area. At low cycle numbers the frictional sliding track of the as-received 304 stainless steel meanders and forms slip bands adjacent to the sliding track. Due to instability of the gradient structure of 304 SMAT processed stainless steel, asperities are formed in the inner zone of sliding tracks at increasing cycle numbers. [ABSTRACT FROM AUTHOR]

Sparse isolated pebbles and cobbles of extraformational lithologies are occasionally found in fine-grained deep-water sediments. In the Middle and Upper Liassic deep-water marly limestones and marlstones of Rosso Ammonitico facies (Morbio and Rosso Ammonitico Lombardo Formations) in the western Southern Alps, Lombardy and Ticino, outsized 'exotic' clasts of volcanic and basement rocks occur sporadically. The clasts, of pebble size, are typically rounded. The rhyolitic volcanic clasts can be related to the Permian volcanic succession of the western Southern Alps, from which they must have been reworked; a quartzite pebble is obviously derived from the Hercynian basement. The clasts are best interpreted, in analogy to other occurrences, as dropstones transported to the site of final deposition by drift wood that occasionally occurs in the pelagic sediments. The only possible source area must be situated to the west of Lago Maggiore where the Permian volcanic suite was exposed in a fault block uplifted in the course of latest Triassic-Early Jurassic rifting. [ABSTRACT FROM AUTHOR]

Diamonds have substantial hardness and durability, but attempting to deform diamonds usually results in brittle fracture. We demonstrate ultralarge, fully reversible elastic deformation of nanoscale (~300 nanometers) single-crystalline and polycrystalline diamond needles. For single-crystalline diamond, the maximum tensile strains (up to 9%) approached the theoretical elastic limit, and the corresponding maximum tensile stress reached ~89 to 98 gigapascals. After combining systematic computational simulations and characterization of pre- and postdeformation structural features, we ascribe the concurrent high strength and large elastic strain to the paucity of defects in the small-volume diamond nanoneedles and to the relatively smooth surfaces compared with those of microscale and larger specimens. The discovery offers the potential for new applications through optimized design of diamond nanostructure, geometry, elastic strains, and physical properties. [ABSTRACT FROM AUTHOR]

Rudolf Trümpy (1921-2009) was one of the great Alpine geologists of the twentieth century and an influential figure in the international geological community. He played a dominant role in the change of opinion concerning the Alpine evolution by showing that normal faulting dominated the early development of the Alpine realm from the Triassic to the early Cretaceous. This provided a convenient model for later plate-tectonic interpretations of collisional mountain belts. His further recognition of strike-slip faulting during all stages of the Alpine evolution presaged the realisation that the Alps were not built by a simple open-and-shut mechanism. Trümpy was educated during an intellectual lull, a time when simplistic models of the earth behaviour inherited from the middle of the nineteenth century became prevalent under the influence of a close-minded, positivist approach to geological problems. This period, which we term the Dark Intermezzo, lasted from about 1925 to 1965. The grand syntheses of Suess and Argand which preceded this period were viewed from this narrow angle and consequently misunderstood. It was thought that earth history was punctuated by global orogenic events of short duration taking place within and among continents and oceans whose relative positions had remained fixed since the origin of the planet. These views, summarised under the term 'fixism', were developed when the ocean floors were almost totally unknown. When data began coming in from the post World War II oceanographic surveys, the world geological community was slow to receive and digest them. Trümpy followed these developments closely, realising that his work was important in placing the geology of the mountain belts within the emerging, new theoretical framework. He adopted the position of a critic and emphasised where detailed knowledge of the Alps, unquestionably the best known mountain belt in the world, supported and where it contradicted the new ideas. His voice was listened to carefully and subsequent developments have shown his critique to have been prescient. It is regrettable that he did not publish some of the theoretical criticisms he communicated to his colleagues during scientific meetings and informal conversations. His hesitance in becoming involved in theoretical arguments in geology may have stemmed partly from his scientific upbringing during the Dark Intermezzo and partly because he genuinely believed that he was better off sticking to what he thought he knew for sure. He nevertheless stressed that it is important for geologists 'to dream'. It is often said about teachers that one should do what they say, not what they do. In Trümpy's case, it was the opposite. Both scientifically and as a human being, he was a most admirable man. [ABSTRACT FROM AUTHOR]

An obituary for Hans P. Laubscher, Professor emeritus of Geology at the University of Basel, is presented.

Abstract: Before the theory of plate tectonics took hold, there was no coherent model for ocean–continent transitions that included both extant continental margins and fragmentary ancient examples preserved in orogenic belts. Indeed, during the early 1900, two strands of thought developed, one relying on the antiquity and permanence of continents and oceans, advocated by the mainstream of the scientific community and one following mobilist concepts derived from Wegener''s hypothesis (1915) of continental drift. As an illustration of the prevailing North-American view, the different composition and thickness of continental and oceanic crust and the resulting isostatic response showed “how improbable it would be to suppose that a continent could founder or go to oceanic depth or that ocean floor at ±3000 fathoms could ever have been a stable land area since the birth of the oceans” [H.H. Hess, Trans. R. Soc. London, A 222 (1954) 341–348]. Because of the perceived permanence of oceans and continents, mountain chains were thought to originate from narrow, elongated, unstable belts, the geosynclines, circling the continents or following “zones of crustal weakness” within them, from which geanticlines and finally mountain belts would develop. This teleological concept, whereby a geosyncline would inevitably evolve into a mountain chain, dominated geological interpretations of orogenic belts for several decades in the mid-twentieth century. However, the concept of permanence of oceans and continents and the concept of the geosyncline had already met with the critiques of Suess and others. As early as 1905, Steinmann considered the association of peridotite, “diabase” (basalt/dolerite) and radiolarite (a typical ocean–continent transition assemblage), present in the Alps and Apennines, as characteristic of the deep-ocean floor and Bailey (1936) placed Steinmann''s interpretation into the context of continental drift and orogeny. Indeed, in both authors’ writings, the concept of ophiolites as ocean crust is apparent. Between 1920 and 1930, the stage was thus potentially set for modern mobilist concepts that were, however, to prove attractive to only a small circle of Alpine and peri-Gondwanian geologists. After the Second World War, the 1950s saw the rapid progress of the geophysical and geological exploration of oceans and continental margins that provided the data for a reevaluation of the geosynclinal concept. Actualistic models now equated the former preorogenic miogeosyncline of Stille (1940) and Kay (1951) with passive continental margins [C.L. Drake, M. Ewing, G.H. Sutton, Continental margin and geosynclines: the east coast of North America, north of Cape Hatteras, in: L. Ahrens, et al. (Eds.), Physics and Chemistry of the Earth 3, Pergamon Press, London, 1959, pp. 110–189], the (American version of the) eugeosyncline and its igneous rocks with “collapsing continental rises” [R.S. Dietz, J. Geol. 71 (1963) 314–333] and the ophiolites, the Steinmann Trinity, of the (European) eugeosyncline with fragments of oceanic lithosphere [H.H. Hess, History of ocean basins, in: Petrologic Studies: a Volume to Honor A.F. Buddington, Geol. Soc. Am., New York. 1962, pp. 599–620]. The concept of sea-floor spreading [H.H. Hess, History of ocean basins, in: Petrologic Studies: a Volume to Honor A.F. Buddington, Geol. Soc. Am., New York. 1962, pp. 599–620; H.H. Hess, Mid-oceanic ridges and tectonics of the sea-floor, in: W.F. Whittard, R. Bradshaw (Eds), Submarine Geology and Geophysics, Colston Papers 17, Butterworths, London, 1965, pp. 317–333] finally eliminated the weaknesses in Wegener''s hypothesis and, with the coming of the “annus mirabilis” of 1968, the concept of the geosyncline could be laid to rest. Ocean–continent transitions of modern oceans, as revealed by seismology and deep-sea drilling, could now be compared with the remnants of their ancient counterparts preserved in the Alps and elsewhere. [Copyright &y& Elsevier]

In contrast to Northern Europe where, in the 19th Century, a coherent lithostratigraphy and biostratigraphy was established, many of the ‘odd rocks of mountain belts’ (as christened by Alfred G. Fischer) of the Alpine-Mediterranean region defied an easy interpretation in terms of the simple English layer-cake stratigraphy mapped by William Smith. However, as early as 1862, Eduard Suess recognized close affinities between Mesozoic faunas of the Alps and those of the Himalaya. Suess also described many such Alpine sedimentary rocks as pelagic (a term discussed by Antoine Lavoisier in the context of sea-level change), and the results of the Challenger Expedition (1872 to 1876) convinced the Viennese school of geologists of their deep-water nature. Based on the composition of Jurassic–Cretaceous faunas, Melchior Neumayr postulated the existence of an equatorial ocean, the ‘Central Mediterranean’ which extended from Central America through the Alpine belt to the Himalaya and beyond, an ocean which Suess subsequently named ‘Tethys’. The question of whether or not deep-sea sediments could occur on land, as deliberately posed by Gustav Steinmann in 1925, became central to the long-lasting controversy on the permanency of continents and ocean basins. Indeed, the occurrence of deep-sea deposits in mountain belts required the disappearance of oceanic areas and a mobilist concept of orogeny that was subsequently applied to the Tethyan region by Emile Argand in the wake of the continental drift hypothesis of Alfred Wegener. Implicit in the views of Wegener and Argand is the concept of an oceanic crust fundamentally different from that of the continents. Although ophiolites had been recognized as a special group of rocks in the early 19th Century, Steinmann was the first to interpret the association of (serpentinized) peridotite, ‘diabase’ (dolerite–basalt) and radiolarite (Steinmann Trinity) in a geodynamic context and to consider it as characteristic of the deep ocean. The comparison of Alpine radiolarites with Recent radiolarian oozes deposited below the calcite compensation depth did not remain unchallenged, because of the local association of these siliceous rocks with coarse clastic deposits. However, after the advent of the turbidity-current hypothesis, these detrital deposits were reinterpreted as submarine mass-flow deposits. Consequently, such typical Tethyan facies as Rosso Ammonitico, Maiolica/Biancone and black shales, found in close stratigraphical association with the radiolarites, could be interpreted as deposited on deeply submerged continental and/or oceanic crust where they recorded faithfully a range of interdependent palaeoceanographic phenomena: changes in the relative proportion of siliceous, carbonate and organic-walled biota, in carbonate saturation of sea water, in oceanic circulation and in the impact of orbital-climatic cycles. The results of the Deep Sea Drilling Project, with its discovery of typical Jurassic and Cretaceous Tethyan facies in the Atlantic Ocean, dramatically confirmed the early interpretations of European geologists of the 19th and early 20th Centuries. [ABSTRACT FROM AUTHOR]

The concept of turbidite has evolved so much since its original definition by Kuenen and Migliorini in 1950 – i.e. the deposit of turbidity currents exemplified by the sandy flysch successions of the Northern Apennines – that it is now used to define a variety of deposits, some of which have little in common with sandy flysch formations in terms of facies, geometry and geological significance. The extension of the concept to other geodynamic settings and deposits of non-siliciclastic composition is considered only briefly in the concluding sections. With the diffusion of the concept of turbidity current, in the 1950s and early 1960s, an entirely new branch of sedimentology came into being, concerned with the inventory of sedimentary structures, palaeocurrent measurements and bedding patterns. The most representative expression of this branch came from the ‘Dutch school’ of Philip H. Kuenen and his students. Between the late 1960s and the mid-1970s, there was a new development: facies analysis, in terms of modern environments and depositional systems. This development led to the introduction and discussion of ‘fan models’ that became an increasingly thorny issue with the accumulation of data from modern deep-marine settings. In particular, most researchers emphasized the importance of channel and lobe elements and their mutual relationships in space and time... [ABSTRACT FROM AUTHOR]

We challenge the former interpretation of the ‘sedimentary mélange’ of the Makran accretionary complex as a tectonic mélange diapirically emplaced from below and provide evidence for its sedimentary gravitational emplacement from the north during Tortonian–Messinian times (between 11.8 and 5.8 Ma). It is an olistostrome that includes blocks of ophiolites and oceanic sediments derived from the ‘coloured mélange’ to the north, and reworked chunks of the turbidites on which it rests with an erosional truncation. The chaotic scattering of blocks of any size and lithology and the weak, soft-sediment deformation of the matrix argue against a tectonic emplacement of the chaotic formation. Its size and internal structure, together with the size of the individual blocks, make the olistostrome a fossil equivalent of the large, gravitationally emplaced debris flows observed along present-day continental margins and unstable volcanic edifices. [ABSTRACT FROM AUTHOR]

Albert W. Bally, Professor emeritus of Geology at Rice University in Houston, passed away on the 30th of July in Houston. In Switzerland, Bally obtained his baccalaureate and began to study Geology at Zurich University. As Bally noted in his curriculum vitae, 'August 1981 marked my return as geologist to Italy, almost 30 years after publication of my Ph.D. thesis in 1954'. [Extracted from the article]

The article announces that A. M. Celâl Şeng ör has received the Gustav-Steinmann-Medal 2010.

The article presents the author's comments on the contribution of the association Geologische Vereinigung to the development of the field of geology and earth sciences. He says that the organization is celebrating its 100th anniversary in 2010. Its first meeting was held in 1910 at the Senckenberg Museum in Frankfurt, Germany. The author also talks about the periodical "Geologische Rundschau," published by the association.

The article presents a response by the author to Ganapathy Shanmugam comments on the article "Turbidities and turbidity currents from Alpine flysch to the exploration of continental margin". He apologizes for not being clear about the turbidite origin of the coarse-grained division in his paper. He states that Shanmugam did not give much importance to J. E. Sanders while introducing the problem of high-density turbidity currents and sandy debris flows.

The article discusses several issues including the International Geological Congress held in Florence, Italy, the introductory chapter in the 2009 issue and people who made their contributions. The theme of the congress held from 20-28 August 2008 was 'From the Mediterrranean toward a Global Renaissance'. The introductory chapter focuses on chapters which document significance of Mediterranean geology. Several people have been thanked for their contributions including Darrel Cowan and Chim Kopf.

Comment. Provides information on the results of a study on the metamorphic age and geologic significance of the blueschist source terranes. Opposition to the results of this study.

In the Argolis, the Basal Sequence, constituting the eastern Pelagonian margin which bordered the Maliac-Vardar oceanic domain, includes shallow-water carbonates of Late Triassic-Early Jurassic, condensed pelagic limestones of Early-Middle Jurassic, radiolarian cherts of late Middle-Late Jurassic age and siliceous mudstones and sandstones rich in ophiolite fragments. Up-section, coarse breccias, including clasts of boninites derived from the ophiolite obducted onto the Pelagonian margin in Late Jurassic times crop out. Near Angelokastron a small quarry exposes pervasively sheared dark reddish-brown, radiolarian-bearing cherty shales with disrupted fragments of chert and chert nodules impregnated by ferro-manganese oxides. These shales occur in the footwall of a thrust bringing them into contact with the Pantokrator Limestone of the Basal Sequence. We collected more than 30 samples of the chert fragments and the shaly matrix. Thirteen nodules and one matrix sample yielded determinable radiolarians. Low to non-detectable concentrations of trace metals such as Co, Cr, Cu, Ni, Zn, and Pb indicate a hydrothermal origin of the ferro-manganese mineralization. The radiolarian taxa found indicate four age groups for the nodules that are embedded in the siliceous shale matrix that yielded a Middle Jurassic age (middle Bathonian). The first group includes a nodule of Late Triassic age (late Norian to Rhaetian); the second group nodules of Early Jurassic age (late early to late Pliensbachian and probably middle-late Toarcian); the third group nodules of early Middle Jurassic age (Aalenian-Bajocian); the last group finally includes nodules of late Middle Jurassic age (Bajocian-Bathonian). The presence of Upper Triassic to Middle Jurassic Mn-impregnated chert nodules in a Middle Jurassic matrix indicates a deep oceanic environment of deposition outside the Pelagonian realm (easternmost Adria Plate), which at that time was a shallow-water carbonate platform with a thin pelagic limestone cover. The chert nodules are with all certainty derived from the oceanic Maliac-Vardar domain and were, together with their host formation, tectonically emplaced onto the Pelagonian margin. We speculate that these nodules, more lithified than their matrix, were exhumed on the slope of an intra-oceanic accretionary wedge and were redeposited in the Middle Jurassic siliceous mudstones on the floor of the subducting Maliac-Vardar Ocean. [ABSTRACT FROM AUTHOR]

Abstract: Paleostress calculations from fault planes in Paleogene sediments and in the underlying basement were used to determine the orientation and the chronology of the principal stresses during the Cenozoic tectonic evolution of the Kraishte area (southwest Bulgaria). The results show that middle Eocene–early Oligocene WSW–ENE extension led to the formation of grabens and half grabens filled with thick continental to marine deposits in the hanging wall of extensional detachments. The Paleogene sediments and their basement were then intruded by subvolcanic bodies and dykes during SW–NE extension between 32 and 29 Ma. These WSW–ENE and SW–NE extensional stages are related to the general rollback of the Hellenic slab. From the late Oligocene to the earliest Miocene, SSE–NNW transtension generated coal-bearing sedimentary basins. The anticlockwise rotation of the main tensile axis by almost 50° with respect to the previous tectonic stage was probably related to a switch from the Aegean back-arc extension to crustal stretching and extrusion of continental fragments around the Moesian platform. Since the middle Miocene extension in the Kraishte area, accommodated by faults with relatively small displacement, led to the formation of restricted basins filled with alluvial to lacustrine deposits. [Copyright &y& Elsevier]

Abstract: New geochronological and geochemical data from the magmatic rocks of the Kraishte area (SW Bulgaria) reveal the existence of Cadomian arc magmatism intruding an ophiolitic complex. Similar geochemical signatures and crystallization ages of the basic to acidic rocks of the Struma Unit and the Osogovo–Lisets Complex suggest that these rocks were derived from one calc-alkaline magma source. They were parts of a magmatic arc associated during Ediacaran–Early Cambrian (560–540Ma) times with subduction of the Proterozoic Prototethys Ocean. The geochemical analysis of the coeval calc-alkaline granitic magmatism (577–551Ma) in the Morava Nappe reveals a trend from a within-plate towards volcanic-arc affinity. [Copyright &y& Elsevier]

Abstract: A new reconstruction of Alpine Tethys combines plate-kinematic modelling with a wealth of geological data and seismic tomography to shed light on its evolution, from sea-floor spreading through subduction to collision in the Alps. Unlike previous models, which relate the fate of Alpine Tethys solely to relative motions of Africa, Iberia and Europe during opening of the Atlantic, our reconstruction additionally invokes independent microplates whose motions are constrained primarily by the geological record. The motions of these microplates (Adria, Iberia, Alcapia, Alkapecia, and Tiszia) relative to both Africa and Europe during Late Cretaceous to Cenozoic time involved the subduction of remnant Tethyan basins during the following three stages that are characterized by contrasting plate motions and driving forces: (1) 131–84Ma intra-oceanic subduction of the Ligurian part of Alpine Tethys attached to Iberia coincided with Eo-alpine orogenesis in the Alcapia microplate, north of Africa. These events were triggered primarily by foundering of the older (170–131Ma) Neotethyan subduction slab along the NE margin of the composite African–Adriatic plate; subduction was linked by a sinistral transform system to E–W opening of the Valais part of Alpine Tethys; (2) 84–35Ma subduction of primarily the Piemont and Valais parts of Alpine Tethys which were then attached to the European plate beneath the overriding African and later Adriatic plates. NW translation of Adria with respect to Africa was accommodated primarily by slow widening of the Ionian Sea; (3) 35Ma–Recent rollback subduction of the Ligurian part of Alpine Tethys coincided with Western Alpine orogenesis and involved the formation of the Gibraltar and Calabrian arcs. Rapid subduction and arc formation were driven primarily by the pull of the gravitationally unstable, retreating Adriatic and African slabs during slow convergence of Africa and Europe. The upper European–Iberian plate stretched to accommodate this slab retreat in a very mobile fashion, while the continental core of the Adriatic microplate acted as a rigid indenter within the Alpine collisional zone. The subducted lithosphere in this reconstruction can be correlated with slab material imaged by seismic tomography beneath the Alps and Apennines, as well as beneath parts of the Pannonian Basin, the Adriatic Sea, the Ligurian Sea, and the Western Mediterranean. The predicted amount of subducted lithosphere exceeds the estimated volume of slab material residing at depth by some 10–30%, indicating that parts of slabs may be superposed within the mantle transition zone and/or that some of this subducted lithosphere became seismically transparent. [Copyright &y& Elsevier]

Abstract: The Kozara Mountains of northern Bosnia and Hercegovina form part of the internal Dinarides and host two tectonically juxtaposed ophiolitic successions of different age. The southern part of the Kozara Mountains exposes the Western Vardar Ophiolitic Unit, which was obducted onto the Adriatic margin in the Late Jurassic. The northern part exposes a bimodal igneous succession that was thrust onto the Western Vardar Ophiolitic Unit during the latest Cretaceous to Early Paleogene. This bimodal igneous succession comprises isotropic gabbros, doleritic dikes, basaltic pillow lavas and rhyolites. Pelagic limestones, intercalated with pillow lavas, yielded a Campanian globotruncanid association, consistent with concordant U–Pb ages on zircons from dolerites and rhyolites of 81.39±0.11 and 81.6±0.12 Ma, respectively. Chondrite-normalised rare earth element patterns of the bimodal igneous rocks show enrichment of LREE over HREE. Primitive mantle-normalised multi-element diagrams do not reveal significant depletion of HFSE. The εNd(T) and initial 87Sr/86Sr isotopic values range from +4.4 to +6.3 and from 0.70346 to 0.70507 respectively, suggesting an intraoceanic origin. The bimodal igneous succession is unconformably overlain by Maastrichtian to Paleocene siliciclastics that contain abundant ophiolitic detritus, suggesting reworking of the Campanian magmatics. An Eocene turbiditic sandstone succession unconformably covers both the Western Vardar Ophiolitic Unit and the Late Cretaceous bimodal igneous successions. These observations suggest that the Adriatic Plate and the Europe-derived Tisza and Dacia Mega-Units were still separated by a deep basin floored by oceanic lithosphere until the Campanian and that its closure did not occur before the Maastrichtian to earliest Paleogene. This Late Cretaceous oceanic domain probably represented a remnant of the Vardar Ocean, or alternatively, the Alpine Tethys; possibly the traces of both oceanic domains were connected in the area. [Copyright &y& Elsevier]

Abstract: The break-up of continental lithosphere in magma-poor margins is accompanied by the exhumation of mantle and crustal rocks in the footwall of large-scale detachment faults. Although these structures have been described from many modern and ancient margins, little is known about how they accommodate strain and evolve in time and space during continental break-up. The Tasna Ocean–Continent Transition (OCT) in southeastern Switzerland is one of the rare examples where such detachment faults are exposed and can be observed on a kilometre scale. In this paper we describe the deformation structures and their evolution observed along detachment faults in the Tasna OCT. Our results show that continental break-up was attained by a series of detachment faults. These detachment faults accommodated extensional strain in fault zones formed by a localized core zone that is surrounded by a several tens to hundred metres wide damage zones. The core zone corresponds to the zone of highest strain and is well defined structurally by the occurrence of gouges and/or foliated cataclasites and physically by separating a hanging wall from a footwall. Deformation in the fault zones occurred under greenschist facies to seafloor conditions and within the stability field of serpentine. U/Pb ages on zircon from a garnet-bearing pegmatite cross cutting high-temperature shear zones (upper amphibolite facies and higher) provide Carboniferous ages and demonstrate that these shear zones are neither kinematically nor genetically related to the detachment faults observed in the Tasna OCT. Ar/Ar ages on phlogopite from spinel websterite suggest that mantle exhumation occurred during Middle Jurassic time. Our data show that the detachment faults observed in the Tasna OCT formed during latest rifting, post-date major thinning of the crust and onset of mantle serpentinization. These results compare well with those from the deep Iberia margin. Our observations support the idea that rifting leading to continental break-up is a multi-phase process, and that serpentinization is the consequence rather than the reason for strain localization at non-volcanic margins. Apart from the more general implications for the tectonic evolution of continental break-up, our results have some important consequences for the palaeogeographic reconstruction of certain Alpine domains and question the existence of an independent Early Cretaceous Valais ocean in the Alpine realm. [Copyright &y& Elsevier]

We provide new geological and isotope geochemical constraints on the evolution from continental rifting to sea-floor spreading along a segment of the Jurassic Tethyan margin exposed in the Platta and Err nappes (eastern Central Alps). Field observations show that the ocean–continent transition zone is characterized by oceanward-dipping detachment faults leading to the exhumation of subcontinental mantle rocks subsequently intruded by gabbro bodies and dolerite dikes, and covered by pillow basalts and radiolarites. Zircons extracted from gabbros and albitite yield concordant U–Pb ages of 161 ± 1 Ma; their initial ℇHf (+ 14.4 to + 14.9) as well as bulk rock ℇNd values of from gabbros and basalts (+ 7.3 to + 9.5) point to a MORB-type depleted mantle source. These data suggest that the onset of magmatic activity coincides with the latest phase of mantle exhumation along low-angle detachment faults and may be controlled by upwelling asthenosphere beneath a zone of exhumed continental mantle. [ABSTRACT FROM AUTHOR]