bluuebunny/crossref_metadata_2025 huggingface dataset:
Depositional and post‐depositional controls on magnetic signals from saltmarshes on the north‐west coast of Ireland
Authors: Wheeler Andrew J. , Oldfield Frank , Orford Julian D.
Published: March 2003

Magnetic measurements were carried out on samples from two saltmarshes deposited during the last century on the north‐west coast of Ireland. Based on profiles from cliffed saltmarsh edge, mid‐marsh and supratidal locations, the processes that affect the generation and persistence of magnetic properties in environments were investigated. This was done to help in understanding the geochemical processes affecting north‐west Irish coast saltmarshes and to determine the frequency and provenance of sediment‐laden flooding events; hence, disentangling the importance of clastic and organic contributions to saltmarsh growth. Magnetic properties indicate depositional and post‐depositional effects varying on both temporal and spatial scales. The interpretations presented here suggest that both biogenic and diagenetic processes have a strong effect on the magnetic properties recorded: in the former case, the growth of magnetotactic bacteria is the main process; in the latter case, it is reductive diagenesis, associated with organic matter decomposition, that is important. The biogenic and diagenetic effects overprint and degrade the detrital magnetic signatures respectively. This suggests that magnetic measurements within the context of north‐west Irish coast saltmarshes can provide limited information on clastic sediment input to these environments. Comparisons between sites on the north‐west coast of Ireland show similar magnetic properties, despite differences in deposition rates, implying that significant post‐depositional alteration of magnetic properties occurs within the first 20–40 years after deposition. Magnetic properties of north‐west coast Irish saltmarshes are put into a regional context by comparison with magnetic profiles from similar sites.
Measurement of the sortable silt current speed proxy using the Sedigraph 5100 and Coulter Multisizer IIe: precision and accuracy
Authors: Bianchi  , Hall  , McCave  , Joseph
Published: March 2003

The weight percentage and mean size of the 10–63 μm terrigenous silt fraction (termed ‘sortable silt’) of fine‐grained marine sediments have recently been argued to be proxies for near‐bottom palaeocurrent intensity. This paper details the accuracy and precision of the Sedigraph 5100 and the Coulter Multisizer IIe in determining the weight percentage and mean size of the sortable silt at abundances characteristic of deep‐ocean sediments. Three sortable silt standards and a fine silt/clay diluent were generated from natural deep‐sea sediment of the Iceland Basin. These were used to produce silty clays with standard additions of sortable silt ranging from 1% to 20% of the total by weight. Accuracy was measured relative to the size of the pure spike measured by each instrument. At sortable silt abundance >5%, the Sedigraph and the Coulter Multisizer estimate both weight percentage and mean grain size precisely and accurately, while below 5%, instrumental noise degrades their performance. On the basis of the Sedigraph results, a series of percentage errors is defined, which may be applied to sortable silt mean size and weight percentage estimates used in palaeoceanographic near‐bottom current reconstruction. It is suggested that, ideally, palaeocurrent reconstructions should be based on Sedigraph determinations of the 0–63 μm grain size distribution, yielding both mean and abundance, or on Coulter Multisizer determinations of the sortable silt grain size mean. The Coulter Multisizer may prove especially useful in regions of very depleted (<5%) sortable silt component.
Jurassic lagoonal environments and quasi‐abiotic platy limestone accumulation: microbial interventions
Authors: Tribovillard Nicolas , Trichet Jean , Défarge Christian , Trentesaux Alain
Published: March 2003

Within the regressive sequence (eustatic sea‐level fall) that characterizes the French Southern Jura carbonate platform during the Kimmeridgian, a succession of three facies (called here units 1–3) may be observed in a palaeolagoon near Orbagnoux. Unit 1 is a shallow‐water, intensely burrowed, carbonate deposit; unit 2 (consisting of laminated, organic matter‐rich carbonate) represents a shallow lagoonal environment, prone to stromatolite development and organic matter accumulation; unit 3 consists of platy limestones almost devoid of identifiable biota. Trace element distributions indicate that depositional and early diagenetic conditions must have been reducing during deposition of unit 1 and, especially, unit 2, whereas they were much less reducing during deposition of unit 3. However, the latter does not contain body or trace fossils, with the exception of structures interpreted as calcified bacteria. The reasons why the apparently normal marine environment of unit 3 did not allow a normal biota to develop are explored and lead us to propose that: (i) unit 2 may be a Jurassic counterpart of modern kopara deposits (stromatolites of French Polynesian atolls); and (ii) unit 3 may be the result of palaeokopara reworking. This model invokes the extensive intervention of microbes in the formation of these carbonate deposits.
The effects of source rocks and chemical weathering on the petrogenesis of siliciclastic sand from the Neto River (Calabria, Italy): implications for provenance studies
Authors: Le Pera Emilia , Arribas Josè , Critelli Salvatore , Tortosa Amparo
Published: March 2003

Plutonic and gneissic rocks of the Sila Massif in the uppermost portion of the Neto drainage basin (Calabria, Southern Italy) weather and erode under a humid Mediterranean climate. During the development of weathering profiles, a combination of chemical weathering and granular disintegration processes occurred. Chemical weathering involves a loss of both plagioclase (mainly during grus generation) and K‐feldspar (mainly during soil formation). This loss is attributed to transformation of plagioclase to clay minerals and to leaching and dissolution of K‐feldspar. Sand composition is quartzofeldspathic and nearly homogeneous along the main channel of the Neto River, even where the river cuts across a blanket of sedimentary cover. Thus, fluvial transport does not alter sand composition within the Neto drainage basin. Petrographic indices are effective in (1) discriminating between contributions from similar (granite and gneiss) source rocks (Qm/F); (2) relating the provenance of plutoniclastic and gneissiclastic sand found in the headwaters to grus horizons (Qm/F; Q/Rg); and (3) distinguishing between upstream first‐cycle and downstream multicycle sand (Q/Rg). This last distinction is further emphasized by considering both aphanitic and phaneritic varieties of rock fragments (RgRmRs diagram). Chemical weathering is the main sand producer within the regolithic environment in northern Calabria. In addition, rapid erosion resulting from steep slopes removes weathered products, and rapid and short transport leads to minimal sediment maturation. In general, the F/Q index is climate and relief dependent; thus, it should be used in conjunction with palaeoclimatic and palaeophysiographic evidence for provenance interpretations of ancient quartzofeldspathic sandstones.
Volcaniclastic resedimentation in distal fluvial basins induced by large‐volume explosive volcanism: the Ebisutoge–Fukuda tephra, Plio‐Pleistocene boundary, central Japan
Authors: Kataoka Kyoko , Nakajo Takeshi
Published: March 2003

The Ebisutoge–Fukuda tephra (Plio‐Pleistocene boundary, central Japan) has a well‐recorded eruptive style, history, magnitude and resedimentation styles, despite the absence of a correlative volcanic edifice. This tephra was ejected by an extremely large‐magnitude and complex volcanic eruption producing more than 400 km3 total volume of volcanic materials (volcanic explosivity index=7), which extended more than 300 km away from the probable eruption centre. Remobilization of these ejecta occurred progressively after the completion of a series of eruptions, resulting in thick resedimented volcaniclastic deposits in spatially separated fluvial basins, more than 100 km from the source. Facies analysis of resedimented volcaniclastic deposits was carried out in distal fluvial basins. The distal tephra (≈100–300 km from the source) comprises two different lithofacies, primary pyroclastic‐fall deposits and reworked volcaniclastic deposits. The resedimented volcaniclastic succession shows five distinct sedimentary facies, interpreted as debris‐flow deposits (facies A), hyperconcentrated flow deposits (facies B), channel‐fill deposits (facies C), floodplain deposits with abundant flood‐flow deposits (facies D) and floodplain deposits with rare flood deposits (facies E). Resedimented volcaniclastic materials at distal locations originated from unconsolidated deposits of a climactic, large ignimbrite‐forming eruption. Factors controlling inter‐ and intrabasinal facies changes are (1) temporal change of introduced volcaniclastic materials into the basin; (2) proximal–distal relationship; and (3) distribution pattern of pyroclastic‐flow deposits relative to drainage basins. Thus, studies of the Ebisutoge–Fukuda tephra have led to a depositional model of volcaniclastic resedimentation in distal areas after extremely large‐magnitude eruptions, an aspect of volcaniclastic deposits that has often been ignored or poorly understood.
Recent environmental changes in Laguna Mar Chiquita (central Argentina): a sedimentary model for a highly variable saline lake
Authors: Piovano Eduardo L. , Ariztegui Daniel , Moreira Sandra Damatto
Published: March 2003

Abstract Laguna Mar Chiquita, a highly variable closed saline lake located in the Pampean plains of central Argentina, is presently the largest saline lake in South America (≈ 6000 km2). Recent variations in its hydrological budget have produced dry and wet intervals that resulted in distinctive lake level fluctuations. Results of a multiproxy study of a set of sedimentary cores indicate that the system has clearly recorded these hydrological variations from the end of the Little Ice Age (≈ ad 1770) to the present. Sedimentological and geochemical data combined with a robust chronology based on 210Pb profiles and historical data provide the framework for a sedimentary model of a lacustrine basin with highly variable water depth and salinity. Lake level drops and concurrent increases in salinity promoted the development of gypsum–calcite–halite layers and a marked decrease in primary productivity. The deposits of these dry stages are evaporite‐bearing sediments with a low organic matter content. Conversely, highstands are recorded as diatomaceous organic matter‐rich muds. Average bulk sediment accumulation rose from 0·22 g cm−2 year−1 in lowstands to 0·32 g cm−2 year−1 during highstands. These results show that Laguna Mar Chiquita is a good sensor of high‐ and low‐frequency changes in the recent hydrological budget and, therefore, document climatic changes at middle latitudes in south‐eastern South America. Dry conditions were mostly dominant until the last quarter of the twentieth century, when a humid interval without precedent during the last 240 years of the lake's recorded history started. Thus, it is an ideal system to model sedimentary and geochemical response to environmental changes in a saline lacustrine basin.
Laminated sediments in the Bay of La Paz, Gulf of California: a depositional cycle regulated by pluvial flux
Authors: Molina‐Cruz A. , Pérez‐Cruz L. , Monreal‐Gómez M. A.
Published: March 2003

Abstract Core BAP96‐CP, sampled from the deepest part of the Bay of La Paz, Gulf of California, has been analysed sedimentologically taking into account regional climate and oceanography. Laminated sediments at the bottom of the bay are essentially not bioturbated by benthic fauna. A subanoxic condition (O2 < 0·2 mL L−1) inhibits the proliferation of benthic fauna. Within the bay, the relative abundances of terrigenous and biogenic inputs change periodically. The terrigenous input is greater than the biogenic input and apparently experiences larger fluctuations. The terrigenous input dominates in dark laminae, whereas the biogenic input mostly occurs in light laminae. Thus, it is assumed that, down the core, the alternation of dark and light laminae represents cycles in the extent of dilution of the biogenic input by terrigenous input. The terrigenous input into the Bay of La Paz is mostly regulated by pluvial runoff. Thus, its temporal fluctuation follows the periods shown by the regional pluvial regime, particularly the 11·2 year period. This is equal to the frequency of sunspot cycles.
Quantitative analysis of variations in depositional sequence thickness from submarine channel levees
Authors: Skene Kenneth I. , Piper David J. W. , Hill Paul S.
Published: March 2003

Abstract Thickness variations across‐levee and downchannel in acoustically defined depositional sequences from six submarine channel‐levee systems show consistent and quantifiable patterns. The thickness of depositional sequences perpendicular to the channel trend, i.e. across the levee, decreases exponentially, as characterized by a spatial decay constant, k. Similarly, the thickness of sediment at the levee crest decreases exponentially down the upper reaches of submarine channels and can be characterized by a second spatial decay constant, λ. The inverse of these decay constants has units of length and defines depositional length scales such that k−1 is a measure of levee width and λ−1 is a measure of levee length. Quantification of levee architecture in this way allowed investigation of relationships between levee architecture and channel dimensions. It was found that these measures of levee e‐folding width and levee e‐folding length are directly related to channel width and relief. The dimensions of channels and levees are thus intimately related, thereby limiting the range of potential channel‐levee morphologies, regardless of allocyclic forcing. A simple sediment budget model relates the product of the levee e‐folding width and e‐folding length to through‐channel volume discharge. A classification system based on the quantitative downchannel behaviour of levee architecture allows identification of a ‘mid‐channel’ reach, where sediment is passively transferred from the through‐channel flow to the levees as an overspilling flow. Downstream from this reach, the channel gradually looses its control on guiding turbidity currents, and the resulting flow can be considered as an unconfined or spreading flow.
Evolution of the scarab hindwing articulation and wing base: a contribution toward the phylogeny of the Scarabaeidae (Scarabaeoidea: Coleoptera)
Authors: BROWNE JONATHAN , SCHOLTZ CLARKE H.
Published: March 2003

A study is made of the articulation and base of hindwings of Scarabaeidae. The survey is based on an examination of over 150 genera from sixteen scarabaeid subfamilies and taxa of uncertain phylogenetic status. Relationships among all subfamilies of Scarabaeidae are examined here for the first time. The constructed phylogeny shows that the scarabaeid lineage (Scarabaeidae) is comprised of two major lines: an aphodiine line (containing Aphodiinae, including Aegialiini, Aulonocnemis and Scarabaeinae), and an orphnine line (containing Orphninae, Melolonthinae, Acoma, Chnaunanthus, Hopliini, Oncerus, Rutelinae, Dynastinae, Trichiinae, Cetoniinae, Osmoderma and Valginae).
Morphological phylogenetics of Australian gall‐inducing thrips and their allies: the evolution of host‐plant affiliations, domicile use and social behaviour
Authors: Morris David C. , Mound Laurence A. , Schwarz Michael P. , Crespi Bernard J.
Published: March 2003

A phylogeny for seventy‐two species of Australian thrips in the subfamily Phlaeothripinae, based on cladistic analysis of forty morphological adult characters, is presented. We use this phylogeny to infer the evolutionary history of host‐plant affiliations, gall induction and other types of domicile use, and different forms of social behaviour. Maximum parsimony analysis yielded forty‐eight cladograms of length 316, and the strict consensus of these cladograms was well resolved. This phylogeny indicated that: (1) associations of thrips with their host plants tend to be evolutionarily conservative, with monophyletic groups of thrips on the host‐plant generaAcacia,CasuarinaandGeijera, (2) galling has evolved multiple times, on different host plants, (3) transitions in domicile use include changes between galling and living in holes or old galls, between living in glued phyllodes and living in old galls, and between leaf‐feeding and galling, and (4) in three of five cases, inquiline lineages were not closely related to their host lineages and the evolution of inquilinism apparently involved a host‐plant shift. However, in two cases, inquilines were very closely related to their gall‐inducing hosts. Eusocial behaviour (involving soldier castes) has evolved in different lineages from those that exhibit communal behaviour (cooperation in building or defending domiciles), suggesting a lack of direct transition between the two social systems. This phylogeny serves as a framework for future molecular systematic studies, and future comparative analysis of ecology and behaviour in the Phlaeothripinae.
Revision of European species of genus Metaphycus Mercet (Hymenoptera: Chalcidoidea: Encyrtidae), parasitoids of scale insects (Homoptera: Coccoidea)
Authors: Guerrieri Emilio , Noyes John S.
Published: March 2003

Fifty‐three European species of Metaphycus are revised. Three generic synonymies are proposed, nine species are described as new, sixteen new specific synonymies and four new combinations are proposed and lectotypes are designated for three species (lounsburyi, philippiae, timberlakei). A dichotomous key to the species is provided, each species is further characterized by a description and notes are provided on their distribution and known hosts. A host‐parasitoid index for all known European species is provided as an appendix.
Polyphyly of Lordiphosa and its relationships in Drosophilinae (Diptera: Drosophilidae)
Authors: Hu Yao‐Guang , Toda Masanori J.
Published: March 2003

The phylogenetic relationships of Lordiphosa and some taxa in Drosophilinae were analysed on the basis of a total of forty‐one selected drosophilid species. These included eighteen species of five Lordiphosa species‐groups as the main target, twenty‐three species representative of the major drosophiline ingroup taxa and four species of Steganinae as outgroup. Sixty‐eight morphological characters of adults were subjected to cladistic analysis. From the results it is concluded that Lordiphosa is polyphyletic; the Lo. tenuicauda species‐group and genus Nesiodrosophila form a single monophyletic group; Lordiphosa proper (i.e. Lordiphosa spp. minus the tenuicauda group) comprises another monophyletic group; within Lordiphosa proper the fenestrarum, nigricolor and denticeps groups are all monophyletic, but monophyly of the miki group is not strongly supported; genera Hirtodrosophila and Scaptomyza and subgenus Sophophora are all monophyletic; and within Drosophilinae, genus Scaptodrosophila is the first to have split from the main lineage, but the branching order of other clades, Chymomyza, Lordiphosa proper, Sophophora, Hirtodrosophila, Nesiodrosophila+ Lo. tenuicauda group, Scaptomyza, Dorsilopha and subgenus Drosophila, remains unresolved. The topology of maximum parsimony cladograms suggests that Lordiphosa proper lies close to Sophophora as proposed previously, although its phylogenetic position could not be determined conclusively. By contrast, bootstrap values tended to contradict another hypothesis that Lordiphosa and Scaptomyza are sister groups.
Revision of the Neotropical genus Leptochromus Motschulsky (Coleoptera: Scydmaenidae)
Authors: O'Keefe Sean T.
Published: March 2003

AbstractThe Neotropical genusLeptochromusMotschulsky (Coleoptera: Scydmaenidae) is revised, and a phylogenetic analysis of Clidicini is presented.Leptochromusincludes five species distributed from Veracruz, Mexico to Manaus, Brazil.Leptochromus fulvescensMotschulsky,L. mexicanus(Sharp) andL. agilis(Sharp) are considered valid species.Leptochromus bicolorO'Keefe, sp.n. from Veracruz, Mexico andL.palaeomexicanusO'Keefe, sp.n. from Miocene amber from Chiapas are described. Male genitalia and antennae are illustrated for each of the extant species. Female genitalia, mouthparts and other morphological features are illustrated for the type speciesL. fulvescens.For the phylogenetic analysis of Clidicini,PalaeoleptochromusO'Keefe was placed as the sister taxon toLeptochromus, andPapususCasey was placed as the sister taxon toLeptochromus +Palaeoleptochromus.Papususis elevated from synonomy withLeptochromusand the biogeography of Clidicini is discussed.
Variability of the Arctic front during the last climatic cycle: application of a novel molecular proxy
Authors: Rosell‐Melé  , Weinelt  , Sarnthein  , Koç  , Jansen
Published: March 2003

In the Nordic Seas, the Arctic front (AF) marks the boundary between the waters of the North Atlantic Drift/Norwegian Current and those of the Arctic domain. Long‐ or short‐term shifts in the position of the AF may affect climate conditions in the northern hemisphere. Arctic water masses are also the loci of modern open ocean convection; hence, defining these areas in the past is important for reconstructing and modelling ocean circulation and its variability. C37 alkenones are biomarkers for some algae of the Class Prymnesiophyceae (e.g. coccolitho‐phorids such as Emiliania huxleyi). These alga occur in most parts of the oceans, in ice‐free conditions, and are found nowadays throughout the Nordic Seas. We have related the sedimentary abundance of the tetraunsaturated C37 alkenone (C37:4) to two types of water masses in the Nordic seas. In locations affected by Atlantic water masses percentages of C37:4 are less than 5%, whereas in Arctic type water masses these increase to more than 5%. We propose that this observation can be used as a modern analogue to reconstruct the position of the AF in North Atlantic Quaternary sediments. Using this novel molecular proxy we can infer that the southward migration of the AF in the NE Atlantic reached ≈ 50 °N during the last glacial maximum (LGM), but perhaps only 60 °N during the Younger Dryas, and that ocean conditions free of sea ice prevailed throughout the Northern North Atlantic in summer.
Geochemistry and field spectrometry for detecting hydrocarbon microseepage
Authors: Yang  , Zhang  , Van Der Meer  , Kroonenberg
Published: March 2003

Remote sensing detection of hydrocarbon reserves would be a valuable addition to conventional methods used currently. Tests were made in a drilled, proven hydrocarbon area predominantly covered by wheat. Field‐spectroradiometers measured spectral characteristics of wheat and soil associated with hydrocarbon microseepage. Soil gas and secondary carbonate produced only by hydrocarbon microseepage were at anomalously high levels at the oil–water or gas–water boundaries. Kaolinite and illite in the soil have higher percentages above petroleum reservoirs. The inflection point positions of spectra on oil‐field wheat were shifted 7 nm to longer wavelengths than off‐field wheat samples, and can be positively correlated with the delta carbonate and soil‐gas. The absorption of soil spectra at 2.346 mm is at least 0.2% higher over oil‐fields than off‐fields. This research proves that remote sensing can be used in an monocultural agricultural area to detect hydrocarbon microseepage.
Rhyolitic volcanic corridors in magmatic arcs: comparing North Wales and North Island, New Zealand
Authors: Gibbons
Published: March 2003

Exceptionally voluminous arc‐related rhyolitic eruptions from clusters of caldera complexes, as seen in Snowdonia, North Wales (mid‐Caradoc), and North Island, New Zealand (late Neogene‐Quaternary), are characteristically confined within transient, fault‐controlled corridors in continental crust. New Zealand rhyolitic corridors (Coromandel, Central, Taupo) have developed in response to the spearheading of an oceanic arc into continental crust, combined with subduction rollback‐induced extension during clockwise rotation pivoting around central North Island. Inherited high heat flow from earlier arc magmatism, intracrustal plastic deformation, and mantle‐derived magma ponding and fractionation beneath a less dense, fracture‐toughened crust, all contribute synergistically to crustal fusion and catastrophic volcanism. A similar scenario is suggested for the Snowdonia volcanic corridor where at least six major rhyolitic centres were restricted in space and time (Soudleyan‐Woolstonian). After the climactic Snowdonian eruptions, arc magmatism was extinguished in Wales: a fate predicted for New Zealand rhyolitic volcanism as subduction rollback continues.
Positive Eu anomaly development during diagenesis of the K/T boundary ejecta layer in the Agost section (SE Spain): implications for trace‐element remobilization
Authors: Martinez‐Ruiz F. , Ortega‐Huertas M. , Palomo I.
Published: March 2003

K/T boundary geochemical anomalies have been used previously to support the impact event at the end of the Cretaceous. However, impact models and assessment of the extraterrestrial contribution to the boundary sediments should also consider the diagenetic alteration of the impact signatures. Mineralogical and geochemical studies centring on redox proxies reveal differences in trace‐element concentrations at Agost and Caravaca (SE Spain), two of the most complete K/T boundary sections. These differences probably derive from variations in the diagenetic evolution of the ejecta layer. Several redox proxies, such as extensive pyrite formation, high authigenic uranium concentration and positive Eu anomalies, indicate very strong reducing conditions at Agost. Positive Eu anomalies are extremely unusual in sediments, and in this case are interpreted to indicate a highly reducing environment. In such conditions, certain trace elements such as Ir, may have been remobilized, thereby masking the original signature of the impact.
The record of Periadriatic volcanism in the Eastern Alpine Molasse zone and its palaeogeographic implications
Authors: Brügel  , Dunkl  , Frisch  , Kuhlemann  , Balogh
Published: March 2003

Precise provenance analysis of andesite and dacite pebbles from conglomerates in the Eastern Alpine Molasse zone, using geochemical and geochronological methods, provides evidence for a synorogenic volcanic chain in the Eastern Alps which is completely eroded today. This volcanism was related to Periadriatic magmatism along the Periadriatic lineament and took place in the Palaeogene, roughly between 40 and 30 Ma. The occurrence of remnants of these volcanic rocks together with other marker lithologies in the Eastern Alpine Molasse, implies an early to middle Miocene drainage system which was, in some respects, similar to the present Inn river system, but had a considerably larger catchment area, reaching farther south. The Palaeo‐Inn drained the central and eastern sections of the Periadriatic magmatic belt to the northern foreland basin.
Identification of Quaternary thrusts, folds and faults in a low seismicity area: examples in the Southern Alps (France)
Authors: Hippolyte J.‐C. , Dumont T.
Published: March 2003

In low seismicity areas, folds, faults and striated pebbles in recent alluvial deposits can demonstrate the Quaternary activity of tectonic structures and can reveal their kinematics. In the Digne nappe (Southern Alps), an out‐of‐sequence thrust occurred in the late Quaternary in response to WSW‐trending compression. The presence of late Quaternary compressional deformation in the Valavoire thrust could have resulted from the activity of the underlying Durance flexure with a maximum Pliocene–Quaternary uplift rate of about 0.1 mm yr−1. The Quaternary top surface of the Valensole basin, that truncates SW‐vergent thrust propagation folds, is folded above the Lambruissier anticline. Exceptional conditions resulted in the local preservation of this Quaternary fold morphology created with a minimum uplift‐rate of 0.05 mm yr−1 under a NE‐trending compression. At the front of the Digne nappe the deformation is characterized by WSW to WNW trends of compression and low strain rates during the Quaternary period.
Rockfall avalanche deposits associated with normal faulting in the NW of Çanklrl basin: implications for the postcollisional tectonic evolution of the Neo‐Tethyan suture zone
Authors: Seyitoglu G. , Kazancl N. , Karadenizli L. , Şen Ş. , Varol B. , Karablylkoglu T.
Published: March 2003

The NNE‐trending Neo‐Tethyan suture zone between Ankara and Çanklrl, thrusts eastward onto different stratigraphic levels of the Neogene succession; however, its western side shows a normal fault relationship. This E‐vergent tectonic sliver was inactive during the accumulation of the Miocene–Lower Pliocene sedimentary succession and was created by the movement of the North Anatolian Fault Zone and its splay after the late Pliocene, indicating internal deformation of the Anatolian plate. These results are inconsistent with the previous suggestion that intracontinental convergence related to Neo‐Tethyan orogeny continued until the Pliocene (Ankara Orogenic Phase).
Predicting the pinchout distance of shoreline tongues
Authors: Løseth T. M. , Helland‐Hansen W.
Published: March 2003

Sand‐rich shoreline tongues are common features of the stratigraphic record, and many of them are important petroleum reservoirs. The basinward extent of such shallow‐marine deposits is highly variable, from a few to a few hundred kilometres. Although indirect information exists, the question as to what parameters actually cause this variation and their relative importance has not been addressed. Here, it is argued that the sand pinchout distance of regressive‐to‐transgressive shoreline tongues is controlled by (1) the type of depositional system (e.g. fluvial‐, tide‐ or wave‐dominated); (2) the regressive and transgressive shoreline trajectories; and (3) the depth of transgressive erosion. In contrast to the shoreline trajectory, the angle of turnaround, defined by the pathway taken by the regressive and subsequent transgressive shorelines, is simple to measure and gives a first approximation of the pinchout distance. For otherwise equal systems, the pinchout distance is inversely related to the angle of turnaround.
Eastbound sublithosphere mantle flow through the Caribbean gap and its relevance to the continental undertow hypothesis
Authors: Alvarez Walter
Published: March 2003

Recent evidence indicates that beneath the Caribbean a tongue of sublithosphere mantle is flowing from the Pacific to the Atlantic, dragging the overlying lithosphere eastward: (i) Shear‐wave splitting results from beneath the Andean subduction zone and Venezuela suggest mantle flow eastward through the Caribbean. (ii) Volcanic chemistry in Central America indicates a slab source beneath Nicaragua, but a different source in Costa Rica, above the proposed Pacific outflow. (iii) An extinct volcanic arc accreted to the margins of the Caribbean swept eastward through the Caribbean gap between North & South America. The 1982 ‘continental undertow’ model requires shallow‐mantle flow through the Caribbean gap from the Pacific to the Atlantic, if continents have deep roots and if shallow‐mantle flow beneath oceans is decoupled from convection at deeper levels. The new evidence from the Caribbean is thus compatible with the continental undertow model, and perhaps with other models involving decoupled shallow flow.
Backstripping dip‐slip fault histories: apparent slip rates for the Miocene of the Vienna Basin
Authors: Wagreich Michael , Schmid Hanns Peter
Published: March 2003

Backstripped basement subsidence histories from both the hanging wall and the footwall blocks adjacent to synsedimentary normal faults can be used to reconstruct the sense of fault motion through time and to quantify the vertical component of fault slip. Consequently, apparent dip‐slip rates of faults can be calculated for each stratigraphic interval and times of increased fault activity can be distinguished. An application of this method to well data along a transect through the central part of the Miocene Vienna Basin indicates that two distinct phases of faulting occurred during the Karpatian, with rates as high as 3000 m Myr−1. Changes in the sense of movements during the early Karpatian and the earliest Badenian indicate a major rearrangement in the fault patterns. During the early Sarmatian another short pulse of dip‐slip is recorded along the investigated faults.
Fluid migration and origin of a mud volcano in the Northern Apennines (Italy): the role of deeply rooted normal faults
Authors: Capozzi Rossella , Picotti Vincenzo
Published: March 2003

ABSTRACT In the foothills of the Northern Apennines mud volcanoes are locally aligned along active normal faults, which allow surface leakage of fluids derived from deep sources (>3–6 km). The chemical and isotopic analysis of the fluids of a mud volcano, coupled with the reconstruction of its geological setting, allowed an investigation of the processes of migration and fluid flow. The fault system associated with the Regnano mud volcano drains a deep Miocene reservoir (foredeep marine deposits), which supplies formation water and thermogenic methane that has migrated from underlying Mesozoic carbonates. The muds from the volcano contain late Eocene microfossils and are extruded only during paroxysmal events. They have a shallower origin (about 1 km) from the base of Tertiary marine deposits deposited upon the upper tectonic nappe of the chain (Ligurian unit). This case study suggests that normal faults are very effective in controlling surface emissions.
Acoustic evidence for shallow gas accumulations in the sediments of the Eastern Black Sea*
Authors: Ergün Mustafa , Dondurur Derman , Çifçi Günay
Published: March 2003

ABSTRACT The Black Sea contains immense gas accumulations. Exploration of gas accumulations is geologically and economically important because migration of methane in sediments may cause massive slope failures and the methane seeps may indicate deeper hydrocarbon reservoirs. Human activity both in and on the seafloor (oil industry) and natural activity (earthquakes, cyclones) trigger mechanisms for seafloor failure and gas release that may have a local and possibly global environmental impact. Recently, sonar and high‐resolution seismic surveys were carried out to obtain information about the effects of gas and gas‐filled sediments throughout the Turkish margin of the Eastern Black Sea, and shallow gas was detected on the subbottom profiler records. It continues about 25–65 m below the sea floor and is marked by bright and cloudy spots, sometimes pockmarks and acoustic voids. The lower section of the Turkish shelf is an extensive pockmarked plateau. The pockmarks are seen as circular structures with high backscattering on the sonar records.
Molecular characterization of cDNA encoding for adenylate kinase of rice (Oryza sativa L.)
Authors: Kawai Maki , Kidou Shin‐ichiro , Kato Atsushi , Uchimiya Hirofumi
Published: March 2003

Two types of genes (Adk‐a, and Adk‐b) encoding for adenylate kinase (AK, EC 2.7.4.3.) were isolated from the cDNA library constructed from poly(A)+ RNA of rice (Oryza sativa L.). Two cDNAs were heterogeneous at 5′ and 3′ ends of non‐coding sequences and had possible polyadenylation signals. One of the genes, Adk‐a, had 1154 bp sequences encoding 241 amino acid residues, while the other type, Adk‐b, contained 1085 bp sequences encoding for 243 amino acid residues. Homology between Adk‐a and Adk‐b was 73.7% in nucleotide sequences, and 90.8% in amino acid level. Two genes showed about 53% homology to bovine mitochondrial adenylate kinase (AK2) at nucleotide and amino acid levels. Concerning the codon usage of rice AK genes, T was abundant at the third position of a codon in the reading frames.

In order to examine the enzyme activity of the protein encoded by the rice cDNA, Adk‐a was cloned into an expression vector, pUC119, which was introduced into Escherichia coli strain CV2, a temperaturesensitive mutant of adenylate kinase. We found that the transformant carrying the rice Adk‐a gene in the sense orientation recovered cell growth at nonpermissive high temperature (42°C) and expressed enzyme activities higher than the untransformed CV2 and the transformant possessing Adk‐a cDNA in the antisense orientation. These observations suggest that rice Adk‐a codes a biologically active enzyme. Furthermore, sucrose was found to regulate the transcription of AK genes in rice cell cultures. Organ related accumulation of mRNA in whole plants was also found.
Characterization of a pollen‐specific cDNA from sunflower encoding a zinc finger protein.
Authors: Baltz R , Domon C , Pillay DT , Steinmetz A
Published: March 2003

We have isolated, via differential hybridization screening of a floral cDNA library from sunflower, a cDNA clone that hybridizes to a 1100 nucleotide‐long mRNA found exclusively in mature pollen grains. The cDNA encodes a 219 amino acid‐long polypeptide containing two potential zinc fingers alternating with two basic domains. A similar organization is found in the erythroid‐specific transcription factor Eryf1 from chicken and its murine homolog GF‐1. The C‐terminus of the protein contains a sixfold repeat of the pentapeptide sequence (S,T,A)(E,D)TQN. These features suggest that the SF3 protein is a transcription factor required for the expression of late pollen genes. The SF3 gene is a member of a multicopy gene family. A genomic copy of the gene has been isolated and sequenced; it is split by four short, AT‐rich introns.
Inflorescence‐specific genes from Arabidopsis thaliana encoding glycine‐rich proteins
Authors: de Oliveira D.E. , Franco L.O. , Simoens C. , Seurinck J. , Coppieters J. , Botterman J. , Van Montagu M.
Published: March 2003

Genomic and cDNA clones for three inflorescence‐specific genes from Arabidopsis thaliana were isolated and characterized. The genes are tandemly organized in the genome on a 10 kb fragment. The expression of these genes is coordinately regulated in a developmental and organ‐specific pattern. They are expressed predominantly in anthers at the later stage of flower development. The primary structure of the encoded gene products exhibits comparable features consisting of a hydrophobic domain at the N‐terminal region followed by repeated glycine‐rich motifs. Little homology is observed either between the glycine‐rich domain of the three genes or with previously described glycine‐rich proteins from other plant species.
Homologs of the essential ubiquitin conjugating enzymes UBC1, 4, and 5 in yeast are encoded by a multigene family in Arabidopsis thaliana
Authors: Girod Pierre‐Alain , Carpenter Tami B. , van Nocker Steven , Sullivan Michael L. , Vierstra Richard D.
Published: March 2003

The covalent attachment of the 76 amino acid protein ubiquitin is an important prerequisite for the degradation of many eukaryotic proteins. The specificity of this ligation is accomplished in part by a family of distinct ubiquitin conjugating enzymes (E2s) working in concert with specific ubiquitin‐protein ligases (E3s). Three essential E2s in yeast encoded by ScUBC1, −4, and −5 comprise a functionally overlapping E2 subfamily that appears responsible for degrading most abnormal and short‐lived proteins. A 15 kDa E2 protein homologous to this family has been identified previously in wheat germ, designated TaE215kDa (Girod and Vierstra (1993) J. Biol. Chem. 268, 955–960). This E2 is responsible for much of the ubiquitin conjugating activity observed in wheat germ extracts and works together with a unique E3 (designated E3γ) for substrate recognition. In this paper, the cloning of five genes encoding E215kDa from Arabidiopsis thaliana is described (designated AtUBC8—12). They encode 149 amino acid basic proteins 94–98% similar to each other and 88–92% similar to ScUBC4 at the amino acid sequence level. In contrast, AtUBC8—12 are only 55–65% similar to the Arabidopsis E2s encoded by AtUBC1, −4, and −7. The AtUBC8—12 proteins do not contain N‐ or C‐terminal extensions and have the active site at residue Cys‐86, based on their homology with other E2s. Analyses of genomic Southern blots are consistent with the existence of multiple members encoding this E2 subfamily. AtUBC8—12 are transcribed to yield about 800 nucleotide mRNAs that, unlike ScUBC4 and −5, are not strongly induced by heat shock. Expression of AtUBC8 in Escherichia coli results in substantial production of functional E215kDa that works together with wheat E3γ in conjugating ubiquitin to endogenous or added substrates in vitro.
Floral development and expression of floral homeotic genes are influenced by cytokinins
Authors: Estruch J.J. , Granell A. , Hansen G. , Prinsen E. , Redig P. , Van Onckelen H. , Schwarz‐Sommer Z. , Sommer H. , Spena A.
Published: March 2003

Tobacco plants that are somatic mosaics for the expression of a cytokinin‐synthesizing gene have viviparous leaves. Epiphyllous buds can be either vegetative or floral. Floral adventitious buds can be either normal or abnormal. Abnormalities of floral development correlate with: (i) a local activation of the cytokinin‐synthesizing gene, (ii) a drastic increase in floral cytokinin content, and (iii) a decrease in the steady‐state levels of mRNA homologues of the homeotic genes DEFA, GLO and PLENA of Antirrhinum majus. Thus, these data show in planta that cytokinins, a class of phytohormones, are able to alter the development of floral organs and to decrease the expression of three homeotic floral genes.
Nucleotide sequences recognized by the AGAMOUS MADS domain of Arabidopsis thaliana in vitro
Authors: Shiraishi Hideaki , Okada Kiyotaka , Shimura Yoshiro
Published: March 2003

The AGAMOUS gene of Arabidopsis thaliana is a homeotic gene involved in the development of stamens and carpels. This gene encodes a putative DNA‐binding protein sharing a homologous region with the DNA‐binding domains, MADS boxes, of yeast MCM1 and mammalian SRF. To examine the DNA‐binding activity of the AGAMOUS protein, double‐stranded oligonucleotides with random sequences of 40 bp in the central region were synthesized and mixed with the AGAMOUS MADS domain overproduced in Escherichia coli. Oligonucleotides which bound to the MADS domain were recovered by repeated immunoprecipitation with an antibody which recognizes the overproduced protein. From a comparison of the recovered DNA sequences, the consensus sequence of the high‐affinity binding‐sites for the AGAMOUS MADS domain was determined to be 5′‐TT(A/T/G) CC(A/T)6GG(A/T/C)AA‐3′. DNase I footprinting and methylation interference experiments showed that the MADS domain binds to this motif. Comparisons with the binding‐site sequences of other MADS‐box proteins revealed that the MCM1 binding‐sites in a‐mating type‐specific promoters of Saccharomyces cerevisiae show similarities with the binding‐site sequence of the AGAMOUS MADS domain. A synthetic MCM1 binding‐site in the upstream region of the STE2 gene is recognized by the AGAMOUS MADS domain.
Expression of maize Adh1 intron mutants in tobacco nuclei
Authors: Lou Hua , McCullough Andrew J. , Schuler Mary A.
Published: March 2003

In vivo and in vitro gene transfer experiments have suggested that the elements mediating intron recognition differ in mammalian, yeast and plant nuclei. Differences in the sequence dependencies, which also exist between dicotyledonous and monocotyledonous nuclei, have prevented some monocot introns from being spliced in dicot nuclei. To locate elements which modulate efficient recognition of introns in dicot nuclei, the maize Adh1 gene has been expressed in full‐length and single intron constructs in Nicotiana benthamiana nuclei using an autonomously replicating plant expression vector. Quantitative PCR‐Southern analyses indicate that the inefficient splicing of the maize Adh1 intron 1 (57% AU) in these dicot nuclei can be dramatically enhanced by increasing the degree of U1 snRNA complementarity at the 5′ splice site. This indicates that the 5′ splice site plays a significant role in defining the splicing efficiency of an intron in dicot nuclei and that, most importantly, the remainder of this monocot intron contains no elements which inhibit its accurate recognition in dicot nuclei. Deletions in intron 3 (66% AU) which effectively move the 3′ boundary between AU‐rich intron and GC‐rich exon sequences strongly activate a cryptic upstream splice site; those which do not reposition this boundary activate a downstream cryptic splice site. This suggests that 3′ splice site selection in dicot nuclei is extremely flexible and not dependent on strict sequence requirements but rather on the transition points between introns and exons. Our results are consistent with a model in which potential splice sites are selected if they are located upstream (5′ splice site) or downstream (3′ splice site) of AU transition points and not if they are embedded within AU‐rich sequences.
A non‐specific lipid transfer protein from Arabidopsis is a cell wall protein
Authors: Thoma Sharon , Kaneko Yasuko , Somerville Chris
Published: March 2003

Lipid transfer proteins (LTPs), mediate the transfer of phospholipids between membranes in vitro. However, the in vivo function of LTPs is not known. To determine the precise location of a non‐specific LTP from Arabidopsis, a cDNA clone was used to produce an Arabidopsis LTP:protein A fusion. Antibodies raised against the fusion were used to localize the Arabidopsis LTP by immunoelectron microscopy. LTP was found to be located in the cell wall, mainly in epidermal cells. This location appears to be inconsistent with the proposed role of the protein in intracellular lipid transfer.
Secretion of cell wall polysaccharides in Vicia root hairs
Authors: Sherrier D. Janine , VandenBosch Kathryn A.
Published: March 2003

Root hairs of hairy winter vetch (Vicia villosa Roth) synthesize and secrete abundant cell wall matrix polysaccharides, making this an excellent system for the study of secretion during tip growth. Roots with newly formed hairs were preserved by cryofixation and freeze substitution. Cryofixed root hairs showed excellent structural and antigenic preservation. Ultrastructural analyses showed numerous vesicles near the tip and a concentration of Golgi bodies in the subapical region of the hair. The distribution of polygalacturonic acid and xyloglucan in the endomembrane system and cell wall were revealed by immunolabeling, using previously characterized monoclonal antibodies. De‐esterified polygalacturonic acid was present on the external surface of the cell wall, but was not detected within the cell, although chemical de‐esterification revealed abundant antigen in Golgi bodies and secretory vesicles. Methyl‐esterified polygalacturonic acid epitopes were detected within the medial and trans cisternae of Golgi bodies, in secretory vesicles, and throughout the wall, indicating that pectin is secreted in a neutral form and may then be de‐esterified in muro. Xyloglucan was also detected within the trans cisternae of Golgi bodies, secretory vesicles and throughout the cell wall. Double labeling experiments demonstrated that both polysaccharides occur simultaneously in the same Golgi bodies, and that secretory vesicles containing both polygalacturonic acid and xyloglucan deliver the polysaccharides to the cell wall at the growing tip.