bluuebunny/crossref_metadata_2025_split huggingface dataset:
Messinian stromatolite‐thrombolite associations, Santa Pola, SE Spain: an analogue for the Palaeozoic?
Authors: FELDMANN MARK , McKENZIE JUDITH A. 
Published: November 2003

ABSTRACTStromatolite‐thrombolite associations are the dominant facies forming large portions of the Santa Pola carbonate platform (SE Spain) during deposition of the Terminal Carbonate Complex (TCC). The TCC, the last period of marine sedimentation in the Western Mediterranean associated with the Messinian Salinity Crisis, comprises a NE‐SW trending thrombolite reef with occasionally interlayered stromatolite horizons and a predominantply stromatolite and oolite facies in the back‐reef area. The stromatolites are mainly dome shaped, but fine‐columnar or wavy‐undulose forms can occur. The stromatolites form huge bioherms, extending tens to hundreds of metres. They are finely laminated with alternating layers of dolomicrite and dolomicrospar. The dolomicrite layers appear to be a primary dolomite precipitate, whereas the dolomite crystals in the dolomicrospar layers apparently formed around a meta‐stable nuclei which was subsequently dissolved or degraded. The low content of sand‐sized particles in the stromatolitic layers indicates formation under low‐energy conditions, possibly on a tidal flat. As reported from other areas in the Western Mediterranean, deposition of the TCC at Santa Pola was apparently cyclic, whereby stromatolites generally terminate each depositional cycle. Subtidal Conophyton stromatolites, possibly the only known occurrence younger than Palaeozoic, are, however, found on the reef slope at the base of the first TCC depositional cycle. The dolomitic nature of the unadulterated stromatolitic laminations and the association of stromatolites and thrombolites as platform builders were a common feature in the Early Palaeozoic but are unusual in post‐Ordovician carbonate facies. We propose that the conditions during TCC deposition were very restricted, possibly reflecting an environment similar to that of the Early Palaeozoic.
Intermittent saltation
Authors: STOUT J. E. , ZOBECK T. M. 
Published: November 2003

ABSTRACTDuring a typical wind erosion event, large variations in wind strength produce temporal variations in saltation activity. The focus of this paper is on a special type of unsteady behaviour ‐ intermittent saltation ‐ a process characterized by bursts of blowing soil interspersed with periods of inactivity. We report here measurements from a field study designed to measure intermittent saltation during three separate 1‐h periods. Our measurements show that natural wind erosion events consist of intermittent bursts of blowing soil often occupying a small fraction of the total time. We have managed to describe the level of intermittency by a simple and universal mathematical expression. We find that the level of intermittency is governed by whether typical wind fluctuations span the gap between the mean wind speed and threshold wind speed. We propose a nondimensional number which expresses the ratio of these velocity scales, called the relative wind strength, and find that the level of intermittency can be described by a simple distribution function of the relative wind strength.
High‐frequency cycles within Pleistocene forced‐regressive conglomerate wedges (Bradanic area, southern Italy) filling collapse scars
Authors: MASSARI FRANCESCO 
Published: November 2003

ABSTRACTMiddle Pleistocene sedimentation in the Bradanic area (foreland basin of the southern Apennines) took place in a setting in which tectonic tilting created anomalous shelf gradients and where slope failures repeatedly occurred at the front of quickly prograding sedimentary wedges. A coarse‐grained wave‐dominated coastal/deltaic complex consisting of two downstepping, forced‐regressive wedges prograded during the falling stage of a middle Pleistocene glacio‐eustatic fluctuation (P. lacunosa Zone). Conglomerate clinoforms show a dramatic increase in relief and steepness as a result of the infill of collapse scars.Compaction of prodelta mudstones, due to the load of the scar‐filling conglomerates, resulted in a slight deformation of the fills into broad synformal structures, with gentle anticlinal closures at their distal ends. Accommodation space was created, resulting in splitting of the prograding bodies into high‐frequency cycles which are thought to reflect the interaction of localized compactional subsidence with autocyclic shifting of river mouths and/or climatically induced variations in sediment supply. Available chronologic constraints suggest average durations of small‐scale cycles on time‐scales shorter than those of Milankovitch orbital frequencies.This case history highlights the importance of some factors which are often neglected in sequence stratigraphic models, e.g. physiography of the sea floor and localized sediment loading. On one hand, the bulk of falling‐stage wedges can be preserved as they prograde into intraplatform depressions represented by collapse scars; on the other, significant accommodation space is created by compactional subsidence, leading to the splitting of a simple progradational unit into multiple, small‐scale cycles.
Cross‐stratified calcarenites from New Zealand: subaqueous dunes in a cool‐water, Oligo‐Miocene seaway
Authors: ANASTAS ALEXIS S. , DALRYMPLE ROBERT W. , JAMES NOEL P. , NELSON CAMPBELL S. 
Published: November 2003

ABSTRACTCross‐bedded, cool‐water, bioclastic limestones of the Te Kuiti Group on the North Island of New Zealand are composed primarily of bryozoans, echinoderms, and benthic foraminifers. Their prominent, large‐scale, unidirectional cross‐stratification is interpreted as produced by migrating subaqueous dunes on the floor of a 50–100 km wide, north‐east‐trending seaway in water depths of 40–60 m. These dunes are thought to have developed in response to strong, seaway‐parallel, tidal currents combined with a north‐east‐directed, set‐up or oceanic current.Cross‐stratification is organized into four hierarchical levels: (1) cross‐lamination; (2) first‐order sets; (3) second‐order sets; and (4) cross‐stratified successions. The levels are based on increasing degrees of internal complexity. Distinct attributes such as internal organization, cross‐set thickness, foreset shape, and lower bounding‐surface shape are used to describe and interpret the cross‐stratification. All these attributes are here integrated in a new and expanded classification of unidirectional cross‐stratification that emphasizes flow and bedform dynamics rather than overall set shape.Individual cross‐stratified successions are interpreted to have formed by dunes with varying sinuosity, superposition, and flow history, under conditions of different current strength but constant sediment production. Horizontally bedded successions are the result of robust, active dune fields that grew during times of vigorous sediment transport. Formset successions were produced from large compound dunes and are the expression of languid and decaying dune fields that developed during times of decreasing sediment transport. These decaying dunes were gradually smothered by continuously and locally produced bioclastic sediment. Formset cross‐stratified successions are most likely to develop in carbonates, where the sediment is produced in place, than in terrigenous clastics where the sediment is imported.
Sediment transport and bedforms in a carbonate tidal inlet; Lee Stocking Island, Exumas, Bahamas
Authors: GONZALEZ RAMON , EBERLI GREGOR P. 
Published: November 2003

ABSTRACTAn active oolitic sand wave was monitored for a period of 37 days in order to address the relationship between the direction and strength of tidal currents and the resultant geometry, and amount and direction of migration of bedforms in carbonate sands. The study area is situated in a tidal channel near Lee Stocking Island (Exumas, Bahamas) containing an estimated 5.5 to 6 × 105 m3 of mobile oolitic sand. Tidal ranges within the inlet are microtidal and the maximum current velocity at the studied site is 0.6 m s−1. At least 300–400 m3 of mostly oolitic sand are formed within, or brought into, the channel area every year. The tidal inlet is subdivided into an ocean‐orientated segment, in which sand waves are shaped by both flood and ebb tides, and a platform‐orientated segment, where sand waves are mainly shaped by flood tides. The studied sand wave lies on the platformward flood‐tide dominated segment in a water depth of 3.5.4.5 m. During the 37 days of observation, the oolitic and bioclastic sand wave migrated 4 m in the direction of the dominant flood current. The increments of migration were directly related to the strength of the tide.During each tidal cycle, bedforms formed depending on the strength of the tidal current, tidal range and their location on the sand wave. During flood tides, a steep lee and a gentle stoss side formed and current ripples and small dunes developed on the crest of the sand wave, while the trough developed only ripples. The average lee slope of the sand wave is 24.2°, and therefore steeper than typical siliciclastic sand waves. During ebb tides, portions of the crest are eroded creating a convex upward ebb stoss side, covered with climbing cuspate and linguoid ripples and composite dunes. The area between the ebb‐lee side and the trough is covered with fan systems, sinuous ripples and dunes.The migration of all bedforms deviated to a variable degree from the main current direction, reflecting complex flow patterns in the tidal inlet. Small bedforms displayed the largest deviation, migrating at an angle of up to 90° and more to the dominant current direction during spring tides.
Inter‐ and supratidal sedimentology of a fjord‐head estuary, south‐western British Columbia
Authors: GIBSON JONATHAN W. , HICKIN EDWARD J. 
Published: November 2003

ABSTRACTDetailed examination of inter‐ and supratidal delta and floodplain sediments exposed in eroding bank sections at 52 locations along the Squamish River estuary provides the basis for recognizing seven distinct facies within the 5500 m‐long estuary. Estuary sedimentation is initially driven by the development of sand bar complexes along the seaward edge of the intertidal delta. Sedimentation continues within interdistributary bay environments as intertidal sandflats and then tidal marshes develop, Aggradation of the delta within interdistributary bay environments results in a gradual transition from delta to alluvial plain. Of the seven facies identified, only the intertidal sands and tidal marsh deposits provide evidence of their tidal origin.Examination of deposits throughout the riverine estuary reveals a number of gradual yet distinct changes of sediment size, structure, and sequence architecture. These trends record the changing nature of tidal and riverine control on sedimentation along the tidal gradient. Generally, with increasing distance up‐estuary, sediment grain‐size increases, the thickness of fine‐grained overbank deposits decreases, and bedding changes from fine parallel bedding to higher energy bedforms. In addition, fining‐upward successions become capped by coarser sands, facies contacts change from gradational to abrupt and occasionally erosional, and facies successions become increasingly complex and less predictable. Squamish River estuary has been divided into four zones based on sedimentological and stratigraphical evidence, each zone reflecting changes in the relative influence of tidal and riverine control on sedimentation. Each zone contains distinctly different facies sequences, although zone boundaries generally are gradational.
Relations between dune morphology, air flow, and sediment flux on reversing dunes, Silver Peak, Nevada
Authors: NEUMAN C. McKENNA , LANCASTER N. , NICKLING W. G. 
Published: November 2003

ABSTRACTRelations between wind speed, sediment flux and dune morphology were measured for two reversing dunes situated in the south‐western part of the Silver Peak dunefield in Clayton Valley, west‐central Nevada. The larger dune was 120 m in length with a height of 12.5 m and the smaller dune 80 m long and 6 m high. Both dunes were sharp crested, aligned approximately E‐W perpendicular to the dominant wind direction, and had slightly concave stoss profiles. Twenty‐seven rotating cup anemometers were placed (0.3 m elevation) along N‐S transects on each of the dunes. At each anemometer site a passive wedge‐shaped sediment trap was used to measure sediment flux. Amplification of wind speed was observed towards the crest on the stoss side of both dunes with speed‐up factors (ucrest/Ubase) ranging from 1·50–3·19, with a corresponding increase in sediment flux by 1–2 orders of magnitude. In general, the ratio of crest flux to base flux (qc/qt,) increased with increasing incident basal wind speed on both dunes. Direct measurements of the stoss slope variation in sediment flux relative to the dune crest are in good agreement with Owen's transport model. Friction speed (u) was approximated from near surface (0·3 m) point wind speed. Although not all assumptions of the Owen model are upheld, the modified model performance is sufficiently robust to predict short‐term variation in stoss sediment flux on the study dunes.Improved models that adequately account for variation in sediment flux under changing air flow and transport conditions are necessary for the prediction of longterm evolution of dunes. In this regard, further progress in model development will require increased understanding of the spatial and temporal variability of airflow and the short term response of sediment flux to these flow conditions.
Significance of localized pore pressures to the genesis of septarian concretions
Authors: HOUNSLOW MARK W. 
Published: November 2003

ABSTRACTThe burial‐stress and hydrologic conditions existing during concretion formation in mudrocks are evaluated and integrated into a model for the genesis of septarian cracks. Initial concretion cement formation will lower concretion permeability through the filling of pre‐existing pore space. During progressive burial, this may lead to increased excess pore pressure, localized within the concretion body causing a reduction of the effective stress. Analysis of the stress conditions and crack morphology suggests that cracks in septarian concretions result from tensional failure (sub‐critical crack growth), as a consequence of this localized excess pore pressure. Conditions suitable for crack formation will depend upon the magnitude of the excess pore pressure and the stress corrosion limit of the concretion body. A review of the likely strength of such concretions indicates that cracking could be initiated at depths less than 10 m. A variety of observed crack morphologies can be explained with this model, depending upon the spatial distribution of strength and effective stress in the concretion. Crack orientations mostly reflect stress anisotropy, but are also influenced by directional anisotropy in the crack growth rates. Locally increased pore pressure also likely occurs in non‐septarian concretions, but is not sufficient to cause cracking. This enhanced local pressure may assist the crystal surface growth reactions of the carbonate cement. Through this enhancement process, the shape of concretions may be a response to the local anisotropic pore‐pressure contours, which reflect the permeability anisotropy of the concretion and surrounding mudrock.
Nitrogen isotopes in peridotitic diamonds from Fuxian, China: the mantle signature
Authors: Cartigny Pierre , Boyd Stuart , Harris Jeff. , Javoy Marc 
Published: November 2003

Nitrogen isotopes in peridotitic diamonds from Fuxian, China, suggest that the upper mantle δ15N‐value has been globally homogeneous since at least the Proterozoic (−5 to −8‰/ATM), with similar values for subcontinental and MORB mantle. In addition, Fuxian diamonds retain the memory of a primary nitrogen lower in δ15N (down to −25‰). For the first time δ15N‐ values in diamonds match those of enstatite chondrites, supporting a formation of the Earth from such meteorites and the idea of a heterogeneous accretion of the Earth’s volatiles. Nitrogen concentrations in diamonds are believed to depend strongly on the rate of the diamond growth and not to be an indicator of C/N ratios of the fluids from which they grew.
Arabidopsis AtGSTF2 is regulated by ethylene and auxin, and encodes a glutathione S‐transferase that interacts with flavonoids
Authors: Smith Aaron P. , Nourizadeh Saeid D. , Peer Wendy A. , Xu Jinghuai , Bandyopadhyay Anindita , Murphy Angus S. , Goldsbrough Peter B. 
Published: November 2003

SummaryExpression of the Arabidopsis glutathione S‐transferase (GST) gene AtGSTF2 is induced by several stimuli, but the function of this GST remains unknown. We demonstrate that AtGSTF2 expression is also induced by glutathione, paraquat, copper, and naphthalene acetic acid (NAA) via a mechanism independent of ethylene perception, as determined by analysis of the ethylene‐insensitive etr1 mutant. Deletion analyses identified two promoter regions important for regulation of AtGSTF2 expression in response to several of these inducers. Previous studies have suggested that AtGSTF2 interacts with indole‐3‐acetic acid (IAA) and the auxin transport inhibitor 1‐N‐naphthylphthalamic acid (NPA). We show that recombinant AtGSTF2 directly binds IAA, NPA, and the artificial auxin NAA. As NPA may act as an endogenous flavonoid regulator of auxin transport, competition between NPA and flavonoids for binding to AtGSTF2 was examined. Both quercetin and kaempferol competed with NPA for AtGSTF2 binding, indicating that all three compounds bind AtGSTF2 at the same site. In transgenic Arabidopsis seedlings, AtGSTF2::GUS expression occurred at the root–shoot transition zone and was induced in this region, as well as at the root distal elongation zone, after treatment with IAA. In wild‐type seedlings, AtGSTF2 is localized near the plasma membrane of cells in the root–shoot transition zone. However, both AtGSTF2::GUS expression and localization of AtGSTF2 protein were disrupted in flavonoid‐deficient tt4 seedlings. Our results indicate that AtGSTF2 is involved not only in stress responses but also in development under normal growth conditions.
Regiospecific hydroxylation of isoflavones by cytochrome P450 81E enzymes from Medicago truncatula
Authors: Liu Chang‐Jun , Huhman David , Sumner Lloyd W. , Dixon Richard A. 
Published: November 2003

SummaryMining of Medicago truncatula EST databases and screening of a root cDNA library led to the identification of three cytochrome P450 81E subfamily members. Two were functionally characterized by expression in yeast. The recombinant enzymes in yeast microsomes utilized the same isoflavone substrates, but produced different products hydroxylated at the 2′ and/or 3′ positions of the B‐ring. When transiently expressed in alfalfa leaves, green fluorescent protein (GFP) fusions of the isoflavone 2′‐ and 3′‐hydroxylases localized to the endoplasmic reticulum. The isoflavone 2′‐hydroxylase was functional when expressed in Arabidopsis. Differential tissue‐specific and biotic/abiotic stress‐dependent expression patterns were observed for the isoflavone 2′‐hydroxylase and 3′‐hydroxylase genes, suggesting differential involvement of 2′‐ and 3′‐hydroxylated isoflavonoids in pathogen defense and insect‐induced responses, respectively, in Medicago.
Virulence systems of Pseudomonas syringae pv. tomato promote bacterial speck disease in tomato by targeting the jasmonate signaling pathway
Authors: Zhao Youfu , Thilmony Roger , Bender Carol L. , Schaller Andreas , He Sheng Yang , Howe Gregg A. 
Published: November 2003

Summary Pseudomonas syringae pv. tomato strain DC3000 (Pst DC3000) causes bacterial speck disease on tomato. The pathogenicity of Pst DC3000 depends on both the type III secretion system that delivers virulence effector proteins into host cells and the phytotoxin coronatine (COR), which is thought to mimic the action of the plant hormone jasmonic acid (JA). We found that a JA‐insensitive mutant (jai1) of tomato was unresponsive to COR and highly resistant to Pst DC3000, whereas host genotypes that are defective in JA biosynthesis were as susceptible to Pst DC3000 as wild‐type (WT) plants. Treatment of WT plants with exogenous methyl‐JA (MeJA) complemented the virulence defect of a bacterial mutant deficient in COR production, but not a mutant defective in the type III secretion system. Analysis of host gene expression using cDNA microarrays revealed that COR works through Jai1 to induce the massive expression of JA and wound response genes that have been implicated in defense against herbivores. Concomitant with the induction of JA and wound response genes, the type III secretion system and COR repressed the expression of pathogenesis‐related (PR) genes in Pst DC3000‐infected WT plants. Resistance of jai1 plants to Pst DC3000 was correlated with a high level of PR gene expression and reduced expression of JA/wound response genes. These results indicate that COR promotes bacterial virulence by activating the host's JA signaling pathway, and further suggest that the type III secretion system might also modify host defense by targeting the JA signaling pathway in susceptible tomato plants.
OsHAP3 genes regulate chloroplast biogenesis in rice
Authors: Miyoshi Kazumaru , Ito Yukihiro , Serizawa Akiko , Kurata Nori 
Published: November 2003

SummaryWe have isolated three genes that potentially encode a HAP3/nuclear factor‐YB (NF‐YB)/CCAAT binding factor‐A (CBF‐A) subunit of a CCAAT‐box binding complex in rice (Oryza sativa), and named them OsHAP3A, OsHAP3B and OsHAP3C. These genes were expressed in various organs including leaves. In the transgenic rice plants with antisense or RNAi construct of OsHAP3A, reduced expression of not only OsHAP3A but also OsHAP3B and OsHAP3C was observed. These plants had pale green leaves, in which the amount of chlorophyll was reduced and chloroplasts were degenerated. Lamella was not well developed and accumulation of starch was not detected. The degenerated chloroplast formation was accompanied by reduced expression of nuclear‐encoded photosynthesis genes such as RBCS and CAB, while expression of chloroplast‐encoded genes was not affected or rather increased. These results suggest that one or more OsHAP3 genes regulate the expression of nuclear‐encoded chloroplast‐targeted genes and normal development of chloroplasts.
pl‐bol3, a complex allele of the anthocyanin regulatory pl1 locus that arose in a naturally occurring maize population
Authors: Pilu Roberto , Piazza Paolo , Petroni Katia , Ronchi Angela , Martin Cathie , Tonelli Chiara 
Published: November 2003

SummaryThe pl1 gene encodes a MYB‐related transcriptional activator committed to the regulation of anthocyanin biosynthesis in maize. Here, we report the genetic and molecular characterisation of pl‐bol3, an Andean allele displaying features that make it different from all the known pl1 alleles. pl‐bol3 has partial, light‐independent expression, and it is active mainly in the juvenile phase of growth. It has a complex molecular structure, containing multiple pl1 gene copies, thus being the first complex locus discovered in the c1/pl1 family. Although the composite genes of the complex locus encode proteins identical to other functional PL1 proteins, the putative promoters of the pl‐bol3 gene are different from the promoters of Pl‐Rhoades (Pl‐Rh) and pl1 sun‐red alleles. The intensity and the tissue specificity of anthocyanin production directed by pl‐bol3 differ significantly from that of Pl‐Rh and the original pl‐W22, and are specified by the interaction of pl‐bol3 with the different r1/b1 gene family members and the competence of pl‐bol3 to different pigment tissues. This allele represents a natural example of gene duplication and diversification of expression, giving rise to a significant change in phenotype and, in this way, is analogous to the complex r1 locus in maize. Analysis of the pl‐bol3 allele contributes to understanding the generation of diversity associated with multiple‐copy genes and the molecular basis of allele‐specific gene expression.