bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of the Thames drainage system in Early and Middle Pleistocene times
Authors: Green C. P. , McGregor D. F. M. , Evans A. H. 
Published: May 2009

SummaryPre-Anglian terrace stages of the proto-Thames system are traced from the present middle Thames area into Essex and south East Anglia. Gravel composition indicates that each of the main terrace stages is associated with an influx of far-travelled material, probably signifying at least three phases of pre-Anglian glaciation in the south Midlands. Gravel composition also indicates the occurrence of major changes during Early and Middle Pleistocene times in the extent of the Thames catchment, and in the disposition of the main drainage lines. The important role of the Goring Gap in the development of the drainage system is noted, and the nature and distribution of Anglian fluvioglacial gravels are described.
The tectonic significance of Triassic dolomite and cargneule in the Gran Paradiso region, Western Alps
Authors: Vearncombe J. R. 
Published: May 2009

SummaryThe interrelationships of dolomite, anhydrite, gypsum and cargneule (a yellow-brown dedolomitised breccia), are discussed with specific reference to the Gran Paradiso region, Western Alps. The dolomite is a highly deformed rock which occurs along the soles of both early and late-Alpine thrusts. Evidence suggests that cargneule formed late in the geological history of the region. It is suggested that dolomite + anhydrite + water acted as an important decollement horizon. Recent exposure to the surface, hydration of anhydrite to gypsum and dedolomitisation resulted in cargneule formation.
Calcareous algae and Middle Jurassic facies of southern England
Authors: Elliott G. F. 
Published: May 2009

SummaryThe rarity of calcareous green algae (Order Dasycladales, and family Udoteaceae) in apparently suitable Middle Jurassic facies of southern England is summarized. They are well known from Tethyan areas to the south and opportunities for migration and establishment existed then. It is concluded that tolerance for warm but extra-tropical conditions, which exists in some but not all modern representatives of these algae, has developed gradually since Triassic time and was not well established until Cenozoic time. In Middle Jurassic time few species showed this tolerance, hence the very limited occurrences north of the Tethys.
Geochemical prospecting for Cu in Hamash area, Southeastern Desert, Egypt
Authors: Soliman M. M. 
Published: May 2009

SummaryStream sediment surveys were carried out on an area of about 200 km2 in the Hamash area. Results indicated that Cu anomalies are concentrated near the intersection of deep-seated tectonic zones and a block fault in the northeastern and southwestern parts of the district. Geophysical techniques, drilling and bedrock sampling show that the Cu mineralization is at the surface, and encrustations of secondary Cu minerals correspond mainly to sulphide-bearing quartz veins and hydrothermally altered granitic and volcanic rocks. No deposits of commercial interest have been found. Under arid conditions reconusissance survey along secondary dispersion trains proved to be a successful method of delineating small zones of Cu mineralization.
Origin of fine-grained granular rocks in layered intrusions
Authors: Thy P. , Esbensen K. H. 
Published: May 2009

SummaryExtremely fine-grained granular rocks are found interleaved with cumulates in some layered differentiated intrusions. The question arises as to whether these can be interpreted as chilled magmas. If this were so it would allow the liquid line of descent to be determined directly. A study of extremely fine-grained granular rocks in the differentiated, layered basic Fongen–Hyllingen complex, Norway, however, showed rocks of this type to be cumulates. Fluctuations in volatile pressure due to crystallization of a hydrous phase may give rise to modal and grain-size variation in layered intrusions.
Interference fold patterns of the early Precambrian Rock Groups in the Songshan area, China
Authors: Suo Shutian , Liu Ruqi , Ma Xingyuan 
Published: May 2009

SummaryThe Songshan area is located in the southern part of the North China platform, which is one of the most completely cratonized tectonic units of China. Its basement has experienced a complex evolutionary history and was eventually consolidated at the end of early Proterozoic time about 1.7 Ga ago.A systematic study has been made of the deformation history of the lower Proterozoic Songshan Group and the Archean Dengfeng Group. At least two widespread episodes of deformation can be recognised in the early Proterozoic Zhongyue tectonic cycle and three in the Archean Songyang cycle. Large scale and small scale interference patterns of the superimposed folding are investigated with the aim of recognizing possible regularities in their occurrence and of gaining an insight into the regional deformation history. Two important aspects of superimposition relationships are illustrated: the control of earlier structures upon later ones and the reform of the former by thelatter; their geometrical regularities are also dealt with respectively.
Smectite, zeolite, biotite and apatite in the Corallian (Oxfordian) sediments of the Baulking area in Berkshire, England
Authors: Chowdhury A. N. 
Published: May 2009

SummarySignificant quantities of clinoptilolite-heulandite, lesser amounts of low tridymite-cristobalite, sparse euhedral biotite, apatite and fresh plagioclase accompany the abundant smectite in the mudrocks from the Corallian sequence in the Baulking and Uffington boreholes. The association is thought to be genetically related, of volcanic origin and formed from the in situ decomposition of volcanic ash. Smectite concentrations fluctuate, showing five maxima, but are unrelated to lithology and hence to environment. This suggests repeated ash-falls during the Corallian sedimentation in the Berkshire area. The initial volcanic episode appears to have been contemporaneous with the shoaling which initiated Corallian sedimentation in southern England, suggesting a common tectonic control.
Orbicular rhythmic layering in the palabora carbonatite, South Africa
Authors: Moore Alan C. 
Published: May 2009

AbstractThe earliest stage of magmatic activity within the Palabora carbonatite was marked by the intrusion of phosphate-bearing pyroxenite. In good exposures in the north, large-scale (2m diameter) orbicular structures are found. These consist of regularly-spaced alternating dark layers (phlogopite-rich) and light layers (diopside-plus apatite-rich) which, in hand specimen, are very similar to the ‘inch-scale’ planar layering which has been described in layered mafic instrusions. One of the purposes of this paper is to describe these unique features which are currently being destroyed by mining, as they form economic phosphate concentrations.The resemblance of the Palabora orbicules to Liesegang rings has led to the development of a qualitative model whereby the orbicules are regarded as having been formed by concentric periodic precipitation around central cores within dynamically quiet, isolated pockets of largely liquid magma. The controlling parameters are interpreted as being the rates of growth of the constituent minerals and the rates of diffusion of the elements crucial to their growth, i.e. K+, Al3+ and (OH)- for dark layers, and Ca2+ and P5+ for light layers.The presence of these spectacular structures with their delicate layering indicates that at the time of crystallization of the pyroxenites relatively non-turbulent conditions prevailed, and diopside, phlogopite and apatite crystallized essentially coevally. Hence, the vertical large-scale banding in the pyroxenite may also be a function of diffusion controlled processes rather than being caused by separate magma pulses.
Late cretaceous quartz geodes after anhydrite from Burgos, Spain
Authors: Elorza J. J. , Rodriguez-Lazaro J. 
Published: May 2009

AbstractThe present work describes the quartz geodes (cauliflower-like) that appear in a specific level of the Late Cretaceous (north of Burgos). Due to their special characteristics, principally anhydrite relicts and spherulitic quartz (length-slow chalcedony), they are considered as pseudomorphs of anhydrite nodules, formed during early diagenesis. At the same level compact chert nodules sporadically appear, presenting a considerable amount of sponge spicules with fibrous texture (length-fast chalcedony). The silicification of the anhydrite nodules took place before total compaction and cementation of the sediment. The source of silica is principally biogenic (sponge spicules). We offer a hypothesis to explain the formation of the anhydrite nodules since there is no link between the depositional environment and the existence in itself of anhydrite nodules. Indirectly it is possible to see the effects of an arid climate, which have not been recorded in the lithologic column here described.
Stratigraphic classification and nomenclature of the Precambrian–Cambrian transition
Authors: Glaessner M. F. 
Published: May 2009

AbstractRelevant points of general principle and special application to the problem under discussion are quoted selectively from the recently published time scale by Harland et al. (1982) and critically considered. Most of the principles and the resulting names for divisions of the Precambrian–Cambrian transition used in it are accepted. The unique significance of the transition from dominantly chronometric to dominantly chronostratic boundaries based on the ‘biostratigraphic sequence’ is an additional justification for the higher ranks previously given to the Vendian (Era) and its constituent divisions: Varangian (or Varangerian) and Ediacaran (or Ediacarian) Periods. The historic transition begins with the latest of the Proterozoic glaciations (the earlier ones started about 950 m.y. ago) and ends with the exponential diversification of the Metazoa. The causal linkage of the two events is hypothetical. Their stratigraphic sequence is demonstrable on the East European platform where the type section of the Vendian is located, and on the Yangtse platform. Normative, operationally designated boundaries are required for the stratigraphic divisions. The history of life in which there are no sharp initial and terminal boundaries shows clearly a rapid transition from widespread but generally rare occurrences of Vendian, particularly Ediacaran, fossils to ubiquitous, generally ‘shelly’ Palaeozoic (initially Cambrian) faunas of unquestioned biostratigraphic importance. This biohistoric transition is the beginning of the Phanerozoic division of a unique historic process. For the Eon of the stratigraphic scale comprising Palaeozoic to Cainozoic Eras the new term Holozoic is therefore proposed.
Research on the isotopic age of the Sinian–Cambrian boundary at the Meishucun section in Jinning County, Yunnan Province, China
Authors: Xiaofeng Xue 
Published: May 2009

AbstractIn this paper the author describes the results of the Rb-Sr isotopic dating of black shale at the Sinian (Precambrian)–Cambrian boundary at the Meishucun section, Jinning County, Yunnan Province, China. The Sinian and Cambrian strata in eastern Yunnan are well developed, the Sinian–Cambrian boundary section in the vicinity of Meishucun Village in Jinning County being representative. These well developed strata provide excellent conditions for research on the radiometric age of the Precambrian–Cambrian boundary. An Rb-Sr isochron age of 579.7 ±8.2 Ma has been obtained on black shale from the Badaowan Member of the Early Cambrian Qiongzhusi Formation, which occurs at 20 m above the Sinian–Cambrian boundary. So an inferred age of 610±10 Ma is given for the Sinian (Precambrian)–Cambrian boundary.
Surface structures formed by wind activity on a sandy beach
Authors: Vortisch W. , Lindström M. 
Published: May 2009

SummarySandy beaches in humid climate zones can have several structures that may be preserved if covered by aeolian sand. Many structures are caused by humidhesion. This new term is coined for the fixation of sand by wetness in the aeolian sedimentary environment. Humidhesion results in relative firmness of the sand, mimicking cementation. Erosive and accretionary humidhesion structures are described.
Role of lava tubes in flows from the Observatory Vent, 1971 Eruption on Mount Etna
Authors: Guest J. E. , Underwood J. R. , Greeley R. 
Published: May 2009

SummaryThe role of tubes in aa flows may be more important than previously recognized. On Etna they are commonly found in the near-vent areas of aa flows. A study of tubes associated with the 1971 Observatory Vent on Etna suggests that ephemeral boccas on the flow surface downslope of the main vent were fed by tubes.
Dedolomitization of Lower Carboniferous Dolostone in the Wirksworth area, Derbyshire, England
Authors: Munn D. , Jackson D. E. 
Published: May 2009

SummaryLower Carboniferous secondary dolostones are shown to be affected by dedolomitization. The crystals of dolomite most affected are those occurring around calcite-filled rhombohedral pores within the dolostones. Dedolomitization of dolomitized crinoid ossicles also occurs. This is thought to be caused by their greater susceptibility to dedolomitization due to dolomicritization. Dedolomitization and subsequent dissolution, giving an enhanced porosity to the dolostones, are believed to be related to the present-day weathering surface.
Sedimentary stratigraphy of Eocene sheetflood deposits, Southern Pyrenees, Spain
Authors: van der Meulen S. 
Published: May 2009

AbstractThe Eocene Monllobat Formation of the southern Pyrenees accumulated under continental (non-marine) conditions. The total thickness of 180 m consists of seven cycles, defined by coarse member concentrations (often sheets) at the bases. The lateral extent of the sheets defines the fixed positions of eight parallel-trending alluvial systems, separated by narrow zones of fine sediment.Sheetflooding dominated the sedimentation of these eight contemporaneous alluvial systems. The sediment was supplied from the rising axial zone of the Pyrenees. The cycles were caused by variations in tectonic activity. The positions and forms of coarse members were locally determined by contemporaneous faulting and folding of the alluvium.
A new Carboniferous trilobite from Spitsbergen
Authors: Ruitang Wu 
Published: May 2009

AbstractTwo Carboniferous trilobites, Ditomopyge convexa sp.nov. and Paladin (Paladin) sp.ind., are described from the Nordenskiöldbreen Formation in Spitsbergen. The new material is of considerable interest as it extends the known distribution of Carboniferous trilobites and provides further information on palaeobiogeography.
Geochemical compositions and depositional conditions of Upper Jurassic and Lower Cretaceous Yorkshire clays, England
Authors: Dypvik H. 
Published: May 2009

AbstractFifty-three samples from the Oxford, Kimmeridge and Speeton Clays of the Yorkshire area have been analysed petrographically and geochemically, by X-ray diffraction, X-ray fluorescence, atomic absorption and combustion (TOC). Major elements and the following trace elements have been determined: Rb, Sr, Ba, Cr, V, Co, Ni, Cu, Zn and Mo. P2O5, Rb, Ba, Cr and V show positive correlation to the clastic fraction (quartz, feldspar and clay minerals). CaO, MnO, and Sr and to a lesser extent Ni, Cu and Zn seem to be positively correlated to calcite, while Fe2O5, MnO, MgO and Co are linked to siderite. Stratigraphical variations of element/element ratios have been used to obtain sedimentological information from the petrographical and geochemical data.The Oxford Clay, with its coarse and immature clays, was deposited in a regressive development. An upwards shallowing with ventilated deposition of more mature and altered clastic material took place throughout the unit. During deposition of the Kimmeridge Clay more reducing conditions existed and finer grained, smectite-rich sediments were formed. The fine grained Speeton Clay was deposited during changing depositional conditions, varying ventilation in a generally regressive development. Several sedimentological breaks characterize the unit.
The Jurassic transgression and the mid-late Jurassic succession in Milne Land, central East Greenland
Authors: Callomon J. H. , Birkelund T. 
Published: May 2009

SummaryNew ammonite finds indicate that the sea transgressed over the crystalline basement of Milne Land, East Greenland, in Boreal Bathonian time and not in Middle Oxfordian as previously thought. A coral (Enallocoenia callomoniBeauvais) occurring in the transgressive Upper Bathonian deposits is the first hermatypic coral known from the Boreal Middle Jurassic. The unusually complete Boreal Upper Callovian–Oxfordian–Kimmeridgian ammonite succession is described; the faunas include remarkable occurrences of submediterranean genera (Hibolithes, Pachypictonia, Streblites). Finally, the sedimentary and tectonic evolution of Milne Land and adjacent areas in Jurassic time is outlined. It is shown that the area was characterized by gentle block-faulting.
Weichselian (Late Quaternary) ostracods from the Sandnes Clay, Norway
Authors: Lord A. R. 
Published: May 2009

SummaryBoreholes drilled at Sandnes, SW Norway penetrated Quaternary (Weichselian) marine interstadial sediments which contained ostracods. The ostracods, which are analysed and discussed, were found to be indicative of cool, probably sub-arctic, shallow-water conditions. Some evidence of faunal mixing is attributed to the effects of glacial meltwater input into a shallow marine environment.
Arumberia Glaessner & Walter, a review of its potential for correlation in the region of the Precambrian–Cambrian boundary
Authors: Bland B. H. 
Published: May 2009

AbstractArumberia is a large impression fossil which may be allied to the Ediacaran fossils Ernietta and Pteridinium. New finds and published evidence suggest that it was restricted to very shallow, possibly non-marine, environments, and to rocks of latest Precambrian to Lower Cambrian age. Well-preserved material from the Longmyndian shows that it was associated with numerous small spherical structures. At present it is only of broad stratigraphic use, but as the wide range of characters observed becomes better understood it may prove more valuable, especially as it occurs in otherwise poorly fossiliferous environments.
Thrust tectonics: a personal view
Authors: Butler Robert W. H. 
Published: May 2009

AbstractThe structure of fold and thrust belts has been studied for just over one hundred years and has been the subject of a recent international conference at Toulouse, in May 1984. This article reviews some of the recent advances in thrust tectonics from a personal viewpoint, in the light of the Toulouse meeting. Key tools in correctly interpreting thrust systems are the use of balanced (restorable) cross-sections and the resolution of three dimensional fault systems. These analytical methods are now being widely developed and applied to numerous orogenic belts with many surprising results. While our understanding of foreland thrust belts is now probably better than any other structural environment, there is still great uncertainty as to the emplacement-driving mechanisms of these belts. Future work will try to solve these and other outstanding problems and apply the new analytical methods to the interior parts of thrust belts in efforts to restore entire orogens.
Depositional history of southern Tunisia and northwestern Libya in Mid and Late Jurassic time
Authors: Walley C. D. 
Published: May 2009

AbstractThe good exposures of virtually undeformed Callovian and Oxfordian strata along the Djeffara escarpment of southern Tunisia and northwestern Libya have allowed analysis of regional depositional history during this time.A number of lithostratigraphic problems are considered. In Tunisia, the Foum Tatahouine Formation is subdivided into members and in Libya some of the stratigraphic issues are clarified. A correlation between the two sequences is proposed. The widely claimed aeolian origin for the Libyan Chameau Mort Sandstone is rejected.The depositional patterns of the Callovian and Oxfordian strata are described in the context of Mid and Late Jurassic sedimentation in the eastern Ghadames basin of the African craton. After a regressive Bathonian sequence, transgressive conditions commenced in Early Callovian time. In a series of continental–marine cycles, this transgressive sequence culminated in widespread shallow, restricted-marine micritic deposition. A regression in Late Callovian time resulted in emergence marked by a thin but widespread calcrete horizon. In Mid? Oxfordian time a renewed transgression brought in open marine, high-energy, shallow-water carbonates. Later, regressive conditions returned, leading to increasing restriction, and latest Jurassic time saw the first signs of the fluvio-deltaic deposition that was to dominate the region in Early Cretaceous time.
The origin of granite erratics in the Pleistocene Patella beach, Gower, South Wales
Authors: Jenkins D. G. , Beckinsale R. D. , Bowen D. Q. , Evans J. A. , George G. T. , Harris N. B. W. , Meighan I. G. 
Published: May 2009

AbstractRare pebbles of granite have been discovered in the raised Patella beach at Butterslade, Gower, South Wales. Their petrography, trace element geochemistry and the Rb/Sr whole rock age of 55 ± 5 Ma confirm that they are derived from the Lundy granite which is about 49 km to the southwest of Gower. Amino acid analyses of fossil gastropods in the Patella beach have provided an age of 210000 years. Various hypotheses of transportation of pebbles from Lundy and Pembrokeshire to Butterslade are considered. Erratics from Pembrokeshire were probably transported by Pleistocene ice into the area while clasts of Lundy granite were moved by progradation of beach deposits northeastwards towards Gower during glacio-eustatic marine transgressions in the Pleistocene.
The Aristarchus impact event and the effects of target material
Authors: Guest John E. , Spudis Paul D. 
Published: May 2009

AbstractThe relatively well preserved, 42 km diameter lunar impact crater Aristarchus was excavated across the boundary between the Aristarchus Plateau and the mare plains. Previous geological mapping of the different ejecta facies associated with Aristarchus has shown that there are distinct morphological differences between ejecta emplaced on either side of the fault scarp that separates the plateau from the mare. One explanation of this observation is that ejecta behaved in different ways on emplacement depending on the original lithology of the excavated material. To test this proposal, we examine the pre-Aristarchus regional stratigraphy and identify the spectral signatures of each of the material's units. By comparing these data with analysis of the geology and spectral characteristics of the ejecta units, we are able to show the provenance of each of the mappable ejecta facies. The conclusions are consistent with the concept of the crater ejecta asymmetry being related to bedrock characteristics. Using geological mapping, spectral interpretation and present understanding of the impact cratering process, we reconstruct the impact event and suggest how such techniques could be used further to interpret the Moon's composition and history.
Protremaster, a new Lower Jurassic genus of asteroid from Antarctica
Authors: Smith Andrew B. , Tranter T. H. 
Published: May 2009

AbstractA new and well-preserved.asteroid, Protremaster uniserialis (gen. & sp.nov.) is described from the Lower Jurassic (Sinemurian) of Antarctica. This find extends the fossil record of the family Asterinidae and the subfamily Tremasterinae considerably and lends support to the idea that asteroids underwent an important morphological diversification in the late Triassic-early Jurassic.