Earliest Triassic microbialites in Çürük Dag,southern Turkey: composition,sequences and controls on formation

The Permian–Triassic Boundary sequence at Çürük Dag, near Antalya, Turkey, begins with a major erosion surface interpreted as being the Late Permian lowstand, on which lies ca 0·4 m of grainstone/packstone composed of ooids, peloids and bioclasts. Most ooids are superficial coats on fragments of calcite crystals presumed to be eroded from crystal fans which are no longer present. The erosion surface is smooth and shows no evidence of dissolution; the grainstone/packstone contains intraclasts of the underlying wackestone, proving erosion. Next are 15 m of microbialite comprised of interbedded stromatolites, thrombolites, plus beds of planar limestones with small‐scale erosion. The latter comprise a complex interlayering of stromatolitic, thrombolitic and peloidal fabrics and precipitated crystal fans, which form a hybrid of microbialite and inorganic carbonate, together with bioclastic debris and micrite. The Çürük Dag microbialite sequence is repetitious; the lower part is more complex, with abundant stromatolites and hybrid microbialites. Some of the stromatolites are themselves hybrids composed of peloids and crystal fans. In the upper part of the sequence stromatolites are missing and the rock is composed mostly of recrystallized thrombolites that develop upwards from tabular to domal form. The domes form directly below small breaks in microbialite growth where very thin shelly micrites and grainstones/packstones are deposited. Repetition of facies may be controlled by sea‐level change; a deepening‐up model is consistent with the evidence. Stromatolites (with abundant crystal fans) dominate in shallower water, deepening through hybrid microbialite and interlayered sediments to thrombolite, probably no more than a few tens of metres deep, followed by breaks and renewal of microbialite growth. An interpretation of open marine fully oxygenated waters for microbialite growth is consistent with ongoing parallel work that has identified Bairdioid ostracods in the microbialite, a group known to be open marine. However, other researchers have proposed low oxygen conditions for Permian–Triassic boundary facies globally, so work continues to confirm whether the Çürük Dag microbialite grew in dysoxic or normally oxygenated conditions. The principal stimulus for post‐extinction microbialites is likely to be carbonate supersaturation of the oceans. The microbialite sequence is overlain by a further 25 m of grainstone/packstone (without microbialite), followed by Early Triassic shales. Overall, microbialites form a thin aggradational sequence during an overall relative sea‐level rise, consistent with global eustatic rise following the Late Permian lowstand.     

Integration of sedimentology and ground‐penetrating radar for high‐resolution imaging of a carbonate platform

Ground‐penetrating radar has not been applied widely to the recognition of ancient carbonate platform geometries. This article reports the results of an integrated study performed on an Upper Jurassic outcrop from the south‐east Paris basin, where coral bioherms laterally change into prograding depositional sequences. Ground‐penetrating radar profiles illustrate the different bedding planes and major erosional unconformities visible at outcrop. A ground‐penetrating radar profile conducted at the base of the cliff displays a palaeotopographic surface on which the outcropping bioherms settled. The excellent penetration depths of the ground‐penetrating radar (20 m with a monostatic 200 MHz antenna) images the carbonate platform geometries, ranging between outcrop workscale (a few metres) and seismic scale (several hundreds of metres). This study supports recent evidence of icehouse conditions and induced sea‐level fluctuations controlling the Upper Jurassic carbonate production.     

Electron acceleration within coronal loops: A wave-particle process?

A simple model as given which aims at explaining how electrons could be accelerated within solar coronal loops due to their trapping by quasi-monochromatic whistler waves.Proceedings of the Second CESRA Workshop on Particle Acceleration and Trapping in Solar Flares, held at Aubigny-sur-Nère (France), 23–26 June, 1986.     

Global Regularization of the Restricted Problem of Three Bodies

The global regularizing transformations of the planar, circular restricted problem of three bodies are studied. It is shown that all these transformations can be written in the same general form which is the solution of a first order ordinary differential equation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Corporate responses to the CDM: the Indian pulp and paper industry

The key outcomes of the 2006 Nairobi Conference on Climate Change are described, with a particular emphasis on adaptation, the Clean Development Mechanism (CDM) and the future of the United Nations climate change regime beyond 2012. Based on an analysis of the key issues being negotiated, the Nairobi Conference can be understood as an important step in the larger process towards a future climate change regime. Its significance is in establishing the confidence and trust between the key players that will be necessary for the successful completion of the current phase of negotiations and agreement on the post-2012 climate change regime.     

On some long time dynamical features of the Trojan asteroids of Jupiter

The equation of motion of long periodic libration around the Lagrangian point $L_4$ L 4 in the restricted three-body problem is investigated. The range of validity of an approximate analytical solution in the tadpole region is determined by numerical integration. The predictions of the model of libration are tested on the Trojan asteroids of Jupiter. The long time evolution of the orbital eccentricity and the longitude of the perihelion of the Trojan asteroids, under the effect of the four giant planets, is also investigated and a slight dynamical asymmetry is shown between the two groups of Trojans at $L_4$ L 4 and $L_5$ L 5 .     

PUBLICATIONS DE L'ASSOCIATION INTERNATIONALE DES SCIENCES HYDROLOGIQUES

ABSTRACT

The purpose of an hydrometric network is to obtain data giving answers to problems raised by the use of water. The methodology suggested in this paper is essentially based on the regional identification of the actual and potential uses of water, on the estimate of the intensity of their use and on the determination of the hydrological characteristics related to this demand.

The level of accuracy required for these characteristics is an important feature in the rationalization procedure.

The various types of stations are defined according to the purpose of their use and the network considered is on a dynamic basis depending on the evolution of uses. The major results obtained for Quebec by the application of this method are described.     

Lösmaterialackumulationer i blockhaven på Varangerhalvön i Nordnorge—en problemdis- kussion

Malmström, B. og Palmér, O.: Lösmaterialackumulationer i blockhaven på Varangerhalvön i Nordnorge—en problemdiskussion. Geografisk Tidsskrift 82: 82–87, Lund, 15. november 1982.

A type of mounds consisting of unconsolidated deposits mainly situated in blockfields is presented. Comparisons are made with pingo-like remnants in northern Scandinavia described by other authors.     

Sedimentology,palaeoenvironments and biostratigraphy of the Pliocene–Pleistocene carbonate platform of Grande‐Terre (Guadeloupe,Lesser Antilles forearc)

Pliocene and Pleistocene deposits from Grande‐Terre (Guadeloupe archipelago, French Lesser Antilles) provide a remarkable example of an isolated carbonate system built in an active margin setting, with sedimentation controlled by both rapid sea‐level changes and tectonic movements. Based on new field, sedimentological and palaeontological analyses, these deposits have been organized into four sedimentary sequences (S1 to S4) separated by three subaerial erosion surfaces (SB0, SB1 and SB2). Sequences S1 and S2 (‘Calcaires inférieurs à rhodolithes’) deposited during the Late Zanclean to Early Gelasian (planktonic foraminiferal Zones PL2 to PL5) in low subsidence conditions, on a distally steepened ramp dipping eastward. Red algal‐rich deposits, which dominate the western part of Grande‐Terre, change to planktonic foraminifer‐rich deposits eastward. Vertical movements of tens of metres were responsible for the formation of SB0 and SB1. Sequence S3 (‘Formation volcano‐sédimentaire’, ‘Calcaires supérieurs à rhodolithes’ and ‘Calcaires à Agaricia’) was deposited during the Late Piacenzian to Early Calabrian (Zones PL5 to PT1a) on a distally steepened, red algal‐dominated ramp that changes upward into a homoclinal, coral‐dominated ramp. Deposition of Sequence S3 occurred during a eustatic cycle in quiet tectonic conditions. Its uppermost boundary, the major erosion surface SB2, is related to the Cala1 eustatic sea‐level fall. Finally, Sequence S4 (‘Calcaires à Acropora’) probably formed during the Calabrian, developing as a coral‐dominated platform during a eustatic cycle in quiet tectonic conditions. The final emergence of the island could then have occurred in Late Calabrian times.     

Evolution,architecture and hierarchy of distributary deep‐water deposits: a high‐resolution outcrop investigation from the Permian Karoo Basin,South Africa

Sea floor and shallow seismic data sets of terminal submarine fan lobes can provide excellent planform timeslices of distributive deep‐water systems but commonly only limited information on cross‐sectional architecture. Extensive outcrops in the Tanqua depocentre, south‐west Karoo Basin, provide these three‐dimensional constraints on lithofacies distributions, stacking patterns, depositional geometries and the stratigraphic evolution of submarine lobe deposits at a scale comparable with modern lobe systems. Detailed study (bed‐scale) of a single‐lobe complex (Fan 3) over a 15 km by 8 km area has helped to define a four‐fold hierarchy of depositional elements from bed through to lobe element, lobe and lobe complex. The Fan 3 lobe complex comprises six distinct fine‐grained sandstone packages, interpreted as lobes, which display compensational stacking patterns on a 5 km scale. Between successive lobes are thin‐bedded, very fine‐grained sandstones and siltstones that do not change lithofacies over several kilometres and therefore are identified as a different architectural element. Each lobe is built by many lobe elements, which also display compensational stacking patterns over a kilometre scale. Thickness variations of lobe elements can be extremely abrupt without erosion, particularly in distal areas where isopach maps reveal a finger‐like distal fringe to lobes. Lobe deposits, therefore, are not simple radial sheet‐dominated systems as commonly envisaged.