Torngat ultramafic lamprophyres and their relation to the North Atlantic Alkaline Province

Geological mapping and diamond exploration in northern Quebec and Labrador has revealed an undeformed ultramafic dyke swarm in the northern Torngat Mountains. The dyke rocks are dominated by an olivine-phlogopite mineralogy and contain varying amounts of primary carbonate. Their mineralogy, mineral compositional trends and the presence of typomorphic minerals (e.g. kimzeyitic garnet), indicate that these dykes comprise an ultramafic lamprophyre suite grading into carbonatite. Recognized rock varieties are aillikite, mela-aillikite and subordinate carbonatite. Carbonatite and aillikite have in common high carbonate content and a lack of clinopyroxene. In contrast, mela-aillikites are richer in mafic silicate minerals, in particular clinopyroxene and amphibole, and contain only small amounts of primary carbonate. The modal mineralogy and textures of the dyke varieties are gradational, indicating that they represent end-members in a compositional continuum.

The Torngat ultramafic lamprophyres are characterized by high but variable MgO (10–25 wt.%), CaO (5–20 wt.%), TiO₂ (3–10 wt.%) and K₂O (1–4 wt.%), but low SiO₂ (22–37 wt.%) and Al₂O₃ (2–6 wt.%). Higher SiO₂, Al₂O₃, Na₂O and lower CO₂ content distinguish the mela-aillikites from the aillikites. Whereas the bulk rock major and trace element concentrations of the aillikites and mela-aillikites overlap, there is no fractional crystallization relation between them. The major and trace element characteristics imply related parental magmas, with minor olivine and Cr-spinel fractionation accounting for intra-group variation.

The Torngat ultramafic lamprophyres have a Neoproterozoic age and are spatially and compositionally closely related with the Neoproterozoic ultramafic lamprophyres from central West Greenland. Ultramafic potassic-to-carbonatitic magmatism occurred in both eastern Laurentia and western Baltica during the Late Neoproterozoic. It can be inferred from the emplacement ages of the alkaline complexes and timing of Late Proterozoic processes in the North Atlantic region that this volatile-rich, deep-seated igneous activity was a distal effect of the breakup of Rodinia. This occurred during and/or after the rift-to-drift transition that led to the opening of the Iapetus Ocean.     

北疆沙尔布尔提山地区早泥盆-早石炭世沉积相、物源演变及其意义

准噶尔西北部沙尔布尔提山地区下泥盆统到下石炭统的沉积可划分为滨海相和海岸平原相。其中下泥盆统和布克赛尔组底部的乌图布拉克亚组为滨海碎屑岩相,曼格尔亚组为滨海碎屑岩和碳酸盐岩相,芒克鲁亚组为滨海碳酸盐岩相。中泥盆统呼吉尔斯特组为海岸平原相。上泥盆统洪古勒楞组底部为海岸平原相,向中部过渡为滨海碳酸盐岩相,顶部为滨海碎屑岩相。下石炭统黑山头组为滨海碎屑岩相。下泥盆统和下石炭统的古流向总体从北向南,显示研究区以北地区为物源区,即成吉斯-塔尔巴哈台褶皱带。结合沉积相的研究成果,本区可能属成吉斯-塔尔巴哈台褶皱带以南的晚古生代陆缘区。物源演变趋势分析揭示早泥盆世成吉斯-塔尔巴哈台带中的早古生代岛弧发生隆起,为乌图布拉克亚组提供成熟度很低的碎屑物质。随着岛弧被剥蚀殆尽,中、晚泥盆世呼吉尔斯特组和洪古勒楞组沉积时转而接受岩屑型再旋回造山带的物源供应,而早石炭世的物源则为过渡型再旋回造山带区。这种物源变化反映了成吉斯-塔尔巴哈台褶皱带的建造特征和隆起过程。     

West North Pacific typhoon track patterns and their potential connection to Tibetan Plateau snow cover

The spatial characteristics and temporal variability of the West North Pacific (WNP) typhoon tracks are studied by analyzing the spatial pattern and temporal variability of the empirical orthogonal functions (EOFs) of the WNP typhoon track density function (TTDF) from 1945 to 2004. The results show that WNP typhoon tracks exhibit three principal EOF Modes. The first EOF Mode represents the contrasting “active” versus “inactive” typhoons defined by the overall frequency and life span of the typhoons that develop in the WNP basin. The second EOF shows a north–south dipole Mode in the TTDF depicting a seesaw pattern in typhoon frequency between Northeast Asia and Southeast Asia. The third EOF describes an east–west dipole Mode in TTDF depicting a zonal seesaw pattern between typhoons that tend to make landfalls in East Asia and typhoons that tend to stay away from the East Asia landmasses. Further analysis of the EOF time series of the WNP TTDF indicates that an important climatic factor associated with the WNP typhoon activity is the snow cover over the Tibetan Plateau (TP), which is also correlated with the East Asia summer monsoon (EASM). Thus, a mechanism linking the TP snow cover and the WNP typhoon activity is the response of the EASM in the WNP region to the TP snow cover, and the subsequent effect of EASM on the development and steering of the WNP typhoons.     

Alteration patterns related to gold mineralization and their relation to CO2/H2O ratios

Summary The pattern of hydrothermal alteration associated with a gold prospect located within a differentiated iron-rich gabbro sill in the Chibougamau region has been investigated in order to establish the alteration mechanism. The gold mineralization, occurring in east-west trending shear zone, shows a close spatial relationship to zones of intense alteration. Ankerite-sericite-pyrite/ankerite-fuchsite-chlorite/ankerite-sericite-chlorite, and chlorite-calcite-magnetite form four distinct alteration facies which extend outward from the mineralized zones. Detailed mineralogical, petrological and chemical studies show that the iron content of chlorite increases whereas the iron content of the carbonate decreases from the mineralized zone outwards. The hydrothermal alteration pattern is shown to be derived from a single fluid with a high initial CO₂/H₂O ratio. At first, reducing reactions prevailed and, with progressive fluid-rock interaction, the CO₂/H₂O ratio was lowered and oxidation reactions dominated.

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Alterationsmuster in beziehung zur goldmineralisation und dem CO₂/H₂O- Verhältnis

Zusammenfassung Hydrothermale Alterationen in Zusammenhang mit einer Goldvererzung eines differenzierten eisenreichen gabbroischen Sills im Chibougamaugebiet wurden untersucht, um den Umwandlungsmechanismus zu ermitteln. Die Goldvererzung in der Ost-West verlaufenden Scherzone ist eng mit Zonen intensiver Alteration verbunden. 4 deutlich unterscheidbare Alterationsfazics, die mit zunehmender Entfernung von der Vererzung auftreten, sind: Ankerit - Serizit - Pyrit/Ankerit - Fuchsit - Chlorit/Ankerit -Serizit - Chlorit und Chlorit - Kalzit - Magnetit. Detailierte mineralogische, petrographische und geochemische Untersuchungen zeigen, daß sich von der Vererzung weg der Eisengehalt im Chlorit, erhöht, gleichzeitig aber in Karbonaten verringert. Die hydrothermale Alteration ist auf eine einzige fluide Phase mit ursprünglich hohem CO₂/ H₂O-Verhältnis zurückzuführen. Vorherrschend waren zunächst reduzierende Reaktionen. Mit zunehmender Wechselwirkung zwischen Fluid und Gestein erniedrigte sich das CO₂/H₂O-Verhältnis und oxidierende Reaktionen nahmen zu.

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With 9 Figures     

Naturally occurring radionuclides and their geochemical interactions at a geothermal site in the North German Basin

The activities of the most common, naturally occurring radionuclides ²³⁸U, ²²⁶Ra, ²¹⁰Pb, ²²⁸Ra, ²²⁸Th, and ⁴⁰K were measured by gamma-ray spectrometry in samples from reservoir rocks, geothermal fluids, and mineral precipitates at the geothermal research site Groß Schönebeck (North German Basin). Results demonstrated that the specific activity of the reservoir rock is within the range of the mean concentration in the upper earth crust of <800 Bq/kg for ⁴⁰K and <60 Bq/kg for radionuclides of the ²³⁸U and ²³²Th series, respectively. The geothermal fluid showed elevated activity concentrations (up to 100 Bq/l) for ²²⁶Ra, ²¹⁰Pb, and ²²⁸Ra, as compared to concentrations found in natural groundwater. Their concentration in filter residues even increased up to 100 Bq/g. These residues contain predominantly two different mineral phases: a Sr-rich barite (Sr, BaSO₄) and laurionite (PbOHCl), which both precipitate upon cooling from the geothermal fluid. Thereby they presumably enrich the radionuclides of Ra (by substitution of Ba) and Pb. Analysis of these precipitates further showed an increased ²²⁶Ra/²²⁸Ra ratio from around 1–1.7 during the initial months of fluid production indicating a change in fluid composition over time which can be explained by different contributions of stimulated reservoir rock areas to the overall produced fluid.     

Triassic rifts and facies patterns in Western and Central Europe

The Triassic evolution of Western and Central Europe was governed by regional crustal extension that induced the subsidence of a complex network of grabens and troughs. These formed an integral part of the Arctic-North Atlantic and the Tethys-Central Atlantic-Gulf of Mexico rift and rift-wrench systems which, in the course of the Mesozoic and Cenozoic, developed into major break-up axes of Pangea.The Triassic grabens of Western and Central Europe began to subside during the Early Scythian and continued to do so, without evidence for discrete rifting pulses, throughout the Triassic and Early Jurassic. These rifts, in some of which over 4000 m of sediments accumulated, were essentially non-volcanic.Facies patterns of the various Triassic basins and troughs of Western and Central Europe reflect the interplay between different rates of tectonic subsidence, varying amounts of clastic influx and repeated sea-level fluctuations. Whilst Late Permian facies patterns were dominated by the transgressing Arctic Seas, Triassic facies patterns were controlled by cyclical Tethys transgressions that advanced northward and westward through rapidely subsiding grabens.The Triassic evolution of Western and Central Europe reflects the onset of the breakup phase of Pangea and its underlying global plate reorganisation.

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Zusammenfassung Die Entwicklung von West- und Mitteleuropa während der Trias stand unter dem Zeichen der regionalen Krustenausdehnung, die sich in der Absenkung komplexer Grabensysteme widerspiegelt. Die Trias-Gräben von West- und Mitteleuropa sind ein wichtiger Bestandteil der Riftsysteme Arktis-Nordatlantik und Tethys-Zentral Atlantik-Golf von Mexico, denen entlang Pangea im Laufe des Mesozoikum und Kenozoikum auseinanderbrach.Die Trias-Gräben Europas senkten sich vom frühen Skythian an kontinulierlich und ohne diskrete tektonische Pulse ab. Die Gräben, von denen manche bis zu 4000 m Sedimente enthalten, waren im allgemeinen nicht mit Vulkanismus verbunden.Die Fazies der Trias-Serien spiegelt die differenzielle tektonische Subsidenz der verschiedenen Gräben und Tröge wider, so wie Variationen der Sedimentzufuhr und wiederholte Fluktuationen des Meeresspiegels.Ende der Perms zog sich die Arktische See vom nördlichen und südlichen Perm-Becken zurück. Vom späten Skythian an beeinflußten Tethys-Transgressionen die Sedimentation im südlichen Perm-Becken. Erste Transgressionen erreichten dieses durch den Polnischen Trog, später aber auch durch die Burgundische und Hessische Senke. Zu Beginn des Keuper wurde die Meeresverbindung durch den Polnischen Trog unterbrochen.Im nördlichen Perm-Becken ist die Trias in kontinentaler Rot-Fazies entwickelt. Die Arktische See reichte erst im späten Norian in die nördlichsten Teile des Viking-Grabens hinein. Die Rhät-Transgression war der Vorläufer der Spät-Sinemurian-Verbindung der Arktis- und Tethys-Meere durch das Nordsee-Gebiet.In der Mittel- und Spät-Trias stieß die Tethys durch den Biskaya Rift und die davon abzweigenden Gräben nach Westen vor. In der Spät-Trias wurde Iberia seitlich von Meeresstraßen umgeben, die sich durch die Grabensysteme von Nord-Afrika, Neufundland-Lusitania und Biskaya ausdehnten.Ein zyklischer Anstieg des Meeresspiegels während der Trias verursachte eine fortschreitende Ausdehnung der Ablagerungsgebiete. Zeitliche Absenkungen des Meeresspiegels verursachten die Entwicklung regionaler Diskordanzen, besonders entlang den Beckenrändern, z. B. während des mittleren Buntsandsteins, des Mittel-Keupers und an der Rhät-Basis.Die Entwicklung von West- und Mitteleuropa während der Trias spiegelt den Beginn des Zerfalls von Pangea wider und die dafür verantwortliche globale Platten-Reorganisation.

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Résumé L'évolution triasique d'Europe centrale et occidentale a été gouvernée par la distension régionale de la lithosphère qui a donné lieu à l'effondrement d'un système complexe de fossés et de rifts. Ceux-ci font partie intégrale des rifts 1) de l'Arctique et de l'Atlantique Nord et 2) de la Téthys, de l'Atlantique Central et du Golfe du Mexique. C'est le long de ces deux mega-rifts que le continent Pangéen s'est désintégré depuis le Jurassique.Les fossés triasiques de l'Europe Centrale et Occidentale commencèrent à s'affaisser au début du Scythien. Cet affaissement se poursuivit pendant le Trias moyen et supérieur et le Jurassique inférieur sans manifestation, de volcanisme important et de phases tectoniques distinctes. Les sédiments déposés dans ces fossés atteignirent des épaisseurs allant jusqu'à 4000 mètres.Les variations de facies dans ces divers bassins reflètent l'interaction entre les divers degrés de subsidence, les divers apports clastiques et les fluctuations eustatique du niveau des mers.A la fin du Permien les mers arctiques se retirèrent des deux grands bassins permiens de l'Europe. Dès le Scythien supérieur la sédimentation dans le bassin sud fut controlée par les transgressions cycliques des mers de la Téthys. Ces pénétrations se sont effectuées initialement par le fossé Polonais et aussi, pendant le Muschelkalk supérieur, par le fossé de Bourgogne. La fermeture du bras de mer correspondant au fossé Polonais se produisit au début du Keuper.Dans le bassin permien septentrional les dépôts triasiques sont développés en facies continental type «couche rouge». Les mers arctiques n'ont pénétré que la partie la plus septentrionale du fossé Viking et ceci seulement à partir du Norien supérieur. La transgression rhétienne précéda la liaison entre les mers artiques et la Téthys qui s'effectua au Sinémurien supérieur dans la région de la Mer du Nord.Pendant le Triasique moyen et supérieur les mers de la Téthys avancèrent vers l'Ouest d'abord par le fossé de la Baie de Biscaye et plus tard aussi par les fossés algéro-marocains et ceux de Terre Neuve et de Lusitanie.Au Trias, la montée cyclique du niveau des mers se traduit par une expansion saccadée des bassins sédimentaires. Des abaissements temporaires du niveau des mers, par example pendant le Buntsandstein moyen, le Keuper moyen et à la base du Rhétien, correspondent à des discordances régionales le long des marges des bassins sédimentaires.L'évolution de l'Europe Centrale et Occidentale reflète la phase initiale de la désintégration du Continent Pangéen et la réorganisation des plaques lithosphérique sousjacentes.

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List of abbreviations used on figures 3 to 6 BC Bristol Channel Trough - BS North-East Brandenburg Swell - BT Bamble Trough - BU Burgundy Basin - CB Channel Basin - CG Central Graben - CS Celtic Sea Trough - EA Eichsfeld-Altmark Swell - EB Egernsund Basin - ECG East Carpathian Gateway - ET Emsland Trough - GT Glückstadt Trough - HB Horda Basin - HF Haig-Fras Depression - HG Horn Graben - HS Hunte Swell - KB Kish Bank Basin - KT Kraichgau Trough - MB Minches Basin - MF Moray Firth Basin - MNH Mid-North Sea High - MX Manx-Furness Basin - ND North Danish Basin - NF Normandy Fault - NL West Netherland Low - NN North Netherland Swell - NP Nancy-Primasens Basin - OG Oslo Graben - PB Paris Basin - PRT Porcupine Trough - PT Polish Trough - PYF Pays-de-Bray Fault - RFH Ringkøbing-Fyn-High - RS Rügen Swell - SE Slyne-Erris Trough - SMG Silesian-Moravian Gateway - SP Sole Pit Basin - SPF Sticklepath Fault - TB Trier Embayment - TW Thuringian-W.-Brandenburg Depr. - UB Ulster Basin - VB Vosges-Black Forest Highs - VG Viking Graben - WA Western Approaches Trough - WD Weser Depression - WG Worcester Graben - WHB West Hebrides Basin This paper is an extract with modifications from the Geological Atlas of Western and Central Europe, by P. A. Ziegler 1982, published by Shell Internationale Petroleum Maatschappij B. V. and distributed by Elsevier Scientific Publishing Company. In this volume the palaeogeographic maps given in this paper are published with a colour over-lay showing environments of deposition.     

Geochemical and isotopic composition of organic matter in the Kupferschiefer of the Polish Zechstein basin: relation to maturity and base metal mineralization

max vs the present depth of the Kupferschiefer, soluble organic matter (SOM) yields, and relative proportions of saturated and aromatic hydrocarbons of the SOM provide evidence for an oxidative alteration of organic matter in highly mineralized Kupferschiefer samples near the Rote F?ule zones. This is confirmed by differences in the composition of the saturated and aromatic hydrocarbon fractions of the soluble organic matter: Saturated hydrocarbons from Rote F?ule samples are dominated by short-chain n-alkanes and higher abundances of pristane and phytane relative to heptadecane (n-C17) and octadecane (n-C18), respectively, compared with samples more distant to the Rote F?ule zone. Compositional changes of the aromatic hydrocarbon fractions with decreasing distance to that zone are characterized by the occurrence of polycyclic aromatic hydrocarbons and elevated ratios of phenanthrene to methylphenanthrenes that are attributed to demethylation reactions and resulted in a decrease of the methylphenanthrene index (MPI 1). Kupferschiefer samples from the barren zone of the Polish Basin do not show these alteration patterns. The observed variations in organic matter composition with burial depth are consistent with changes due to increasing thermal maturation. Maturity assessment is achieved from MPI 1 and the methyldibenzothiophene ratio (MDR). From the relationship between the maturity of organic matter in terms of vitrinite reflectance values and depth of the Kupferschiefer strata, a continuous increase in reflectance of vitrinite is obtained within the Polish Basin. The alteration pattern of organic matter related to base metal mineralization of the Kupferschiefer corresponds to changes in the isotopic composition of organic carbon and calcite. Kerogen within, or close to, Rote F?ule zone is enriched in ¹³C caused by the preferential release of isotopically light organic compounds through progressive degradation of organic matter. The opposite tendency towards lower δ ¹³C and δ ¹⁸O values of calcite provides evidence for isotopic exchange between carbonate and the oxidizing, ore-bearing solutions and for organic matter remineralization. In contrast, organic matter and calcite from the Kupferschiefer do not show regular trends in δ ¹³C with increasing thermal maturation. Received: 25 June 1999 / Accepted: 1 December 1999     

Relative teleseismic travel-time residuals, North Island, New Zealand, and their relation to upper-mantle structure

Relative travel-time residuals computed from clear P-wave arrivals at fourteen seismograph stations in the North Island, New Zealand, from five deep-focus events in the Banda Sea region, show large spatial variations of up to 3 sec. The variations can be explained by higher than normal velocities in the oceanic lithosphere which is underthrust to depths of 350 km beneath the North Island. After correction for crustal structure, the residuals imply an average P-wave velocity about 11% higher than in the surrounding mantle. The lack of suitable source events at azimuths other than northwest prevents a more detailed investigation by this means.     

Deformation patterns of upper Quaternary strata and their relation to active tectonics,Po Basin,Italy

Despite increased application of subsurface datasets below the limits of seismic resolution, reconstructing near‐surface deformation of shallow key stratigraphic markers beneath modern alluvial and coastal plains through sediment core analysis has received little attention. Highly resolved stratigraphy of Upper Pleistocene to Holocene (Marine Isotope Stage 5e to Marine Isotope Stage 1) alluvial, deltaic and coastal depositional systems across the southern Po Plain, down to 150 m depth, provides an unambiguous documentation on the deformation of previously flat‐lying strata that goes back in time beyond the limits of morphological, historical and palaeoseismic records. Five prominent key horizons, accurately selected on the basis of their sedimentological characteristics and typified for their fossil content, were used as highly effective stratigraphic markers (M1 to M5) that can be tracked for tens of kilometres across the basin. A facies‐controlled approach tied to a robust chronology (102 radiocarbon dates) reveals considerable deformation of laterally extensive nearshore (M1), continental (M2 and M3) and lagoon (M4 and M5) marker beds originally deposited in a horizontal position (M1, M4 and M5). The areas where antiformal geometries are best observed are remarkably coincident with the axes of buried ramp anticlines, across which new seismic images reveal substantially warped stratal geometries of Lower Pleistocene strata. The striking spatial coincidence of fold crests with the epicentres of historic and instrumental seismicity suggests that deformation of marker beds M1 to M5 might reflect, in part at least, syntectonically generated relief and, thus, active tectonism. Precise identification and lateral tracing of chronologically constrained stratigraphic markers in the ¹⁴C time window through combined sedimentological and palaeoecological data may delineate late Quaternary subsurface stratigraphic architecture at an unprecedented level of detail, outlining cryptic stratal geometries at the sub‐seismic scale. This approach is highly reproducible in tectonically active Quaternary depositional systems and can help to assess patterns of active deformation in the subsurface of modern alluvial and coastal plains worldwide.     

Regional hydrogeochemical patterns in ground water of Northwestern Ohio and their relation to Mississippi valley—type mineral occurrences

A cluster of minor Mississippi Valley-type deposits occurs in northwestern Ohio. The district, which forms a northeasterly trending belt that cuts across the Findlay Arch, extends from the Indiana border to the Lake Erie Islands. The minerals of the deposits — chiefly celestite, fluorite and sphalerite with lesser amounts of barite and galena — show variation in both geographic and stratigraphic distribution. Dolomites of Middle Silurian to Middle Devonian age, which are the host rocks, also form an important aquifer system. The deposits are of interest because they might be indicators of economic mineralization at depth.Through a reconnaissance study, one-hundred ground-water samples from shallow wells (less than 50 m deep) were collected across an area of approximately 19 000 km². Recharge takes place in the southern part of the area while ground-water flow is northward towards Lake Erie. The majority of the samples are high in sulfate with the source being evaporites within the carbonate sequence. The remainder of the water samples are rich in bicarbonate. Trend surface maps for the major constituents indicate that the ground-water chemistry for the region is established chiefly by the lithology and the flow system. Trend surface maps for F⁻, Sr and Ba reflect the geographic distribution of the minerals in the deposits. Correlations are weakened, however, due to the influence of geochemical barriers such as SO₄²⁻ on Ba and Sr, and Ca on F⁻. The map for Pb follows the trends of the major constituents instead of the mineralization.In a detailed study across northwestern Sandusky County, which lies near the center of the district, 46 samples were collected in an area of 78 km². Trend surface maps for Ca, Mg, SO₄²⁻ and total dissolved solids reflect the chemistry of the bedrock and display concentrations that increase along the local flow path. Maps for F⁻, Sr and Ba correlate with mineralization in the vicinity, the first of these displaying a local trend and the last two correlating with regional trends.     

Heterogeneity of magmas in relation to their volatile constituents

The petrological model developed here for functional interdependences of principal petrogenic and volatile constituents of magmas brings out the sequences of orderly variations in quantity, composition, and properties of the volatile fraction, as in eruption-effusion-intrusion mechanisms, differentiation, and crystallization of the melts, at different levels of generalization. -- V.P. Sokoloff.     

赣东北珍珠山群的建立及意义

赖家组建于1978年，根据岩性特征曾划分出a,b两段，该组产出恐龙骨骼和恐龙蛋等化石，20多年来在国内外引起关注，1994年赖家组一名被废弃，由两头塘组和赤城山组替代，本文用新修订的“赖家组”代表原赖家组a段地层，赤城山组代表原赖家组b段地层，并对天台盆地上白垩统分布做出修改。     

Environmental characteristics of regional groundwater in relation to fluoride poisoning in North China

More and more data indicated that high- or low-fluoride-bearing drinking water led to endemic diseases in which fluoride poisoning was caused by high levels of fluoride (fluoride ion content >1.0 mg/I) in drinking water. Fluoride poisoning in North China is characterized by pathological changes of bones and teeth. Much attention has been devoted to the study of fluoride-bearing groundwater in North China because regionally groundwater has been the main source of water supply, and fluoride poisoning has developed to the extent that it affects human health seriously. Results from the studies in North China summarized in this article indicate that regional high-fluoride-bearing groundwater has a regular distribution corresponding with the development of endemic fluoride poisoning and has something to do with paleogeographic and paleoclimatic conditions, geology, and hydrogeology, especially with types of hydrogeochemistry, pH value of groundwater, degree of mineralization, and so forth. High-fluoride-bearing groundwater in relation to fluorosis occurs mainly in North China, and many effective measures have been taken to reduce the fluoride content in drinking water and to cure the disease after analyzing the distribution and environmental characteristics of high-fluoride-bearing groundwater.     

Fluid-dynamics driving saline water in the North East German Basin

In several areas of the North German Basin, saline water comes close to, or even reaches the surface. Available data from wells indicate that brine stratification is under unstable conditions in the deeper underground. In order to analyse the possible transport mechanisms, 3D thermohaline simulations have been carried out for two different scenarios. The 3D regional model (230×330 km) indicates that salty water is driven to the surface by hydrostatical forces from the surrounding highlands. In addition, a smaller scale model (10×10 km) has been constructed with a grid resolution accounting for possible convective flow. The results indicate that convective flow may play a dominant role in areas with minor topography. In summary, the complex pattern of near surface occurrences of saline water probably results from the interaction of hydrostatic and thermal forces.     

塔里木盆地志留纪脊椎动物的特征及其沉积相、古环境

20世纪80年代以来,在塔里木盆地西北部柯坪—巴楚地区发现了许多志留纪脊椎动物化石,其中包括无颌类、软骨鱼类等。这些化石的发现和深入研究揭示了塔里木盆地志留纪时期的古地理位置及其格局,进一步确定了塔里木陆块在该时期的古生物地理区应属于塔里木-扬子古脊椎动物生物地理区系。记述了采自塔里木盆地中心2个钻井岩心中的3件早志留世脊椎动物化石,其中1件化石为无颌类的新科、新属、新种。同时对志留纪时期塔里木陆块的沉积特征、古环境进行了分析和探讨。上述研究为油气勘探提供了有价值的科学依据。     

塔里木盆地志留纪脊椎动物的特征及其 沉积相、古环境

20世纪80年代以来,在塔里木盆地西北部柯坪—巴楚地区发现了许多志留纪脊椎动物化石,其中包括无颌类、软骨鱼类等。这些化石的发现和深入研究揭示了塔里木盆地志留纪时期的古地理位置及其格局,进一步确定了塔里木陆块在该时期的古生物地理区应属于塔里木-扬子古脊椎动物生物地理区系。记述了采自塔里木盆地中心2个钻井岩心中的3件早志留世脊椎动物化石,其中1件化石为无颌类的新科、新属、新种。同时对志留纪时期塔里木陆块的沉积特征、古环境进行了分析和探讨。上述研究为油气勘探提供了有价值的科学依据。     

Joint patterns and their relationship to regional trends

An analysis of joint patterns in the Grampians Group rocks o£ Western Victoria has established that the dominant directions are north‐north‐west, east‐north‐east, west‐north‐west, north‐north‐east and north. The master joints are steeply‐dipping structures which formed after the sediments were lithified and folded. The joint‐formation is not genetically related to the folding and post‐dates the emplacement of the igneous intrusions. Joint orientation is independent of lithology and the sediments have reacted as a uniform mass to an applied stress.

The joint pattern conforms with the regional tectonic pattern of faults and lineaments which includes directions of the regmatic shear pattern of Sonder (1947). The jointing and major faulting took place during the Kanimblan Orogeny. The faulting and joint‐formation may have been contemporaneous, the faults being directions along which displacement occurred; conversely the actual movements along faults may have induced the jointing into the sediments.     

Sedimentology of the Baluti Formation in the Galley Derash,Amadiya, North Iraq: insight on carbonate turbidite facies and their depositional environmental

The Baluti Formation is exposed succession of the Rhaetian age (Upper Triassic). These strata are interpreted herein for the first time to redeposit in a deep marine setting (distally steepened carbonate ramp/medial to distal slope) on the northwestern margin of the Neo-Tethys. The Galley Derash section is apparently continuous with no evidence for either subaerial exposure or submarine erosion. The absence of erosional scours in the study area confirms emplacement of these strata below both fair-weather and storm wave base. Event beds, particularly those resulting from sediment gravity flows, dominate the Rhaetian interval. The Upper Rhaetian strata are primarily assigned to the Galley Derash Valley. It records an upward transition from moderate-scale, olistolith-bearing debris flow deposits (debrite) to medium-/thin-bedded turbidites remobilized as sediment slumps/slides. The succession is dominated by medium- to thin-bedded calcareous turbidites and hemipelagic suspension deposits. Very low fossil assemblages, particularly stromatolite fragments, and planktonic bivalves occur within some intervals in the section. Rapid and relatively continuous sedimentation is attested to by the thickness of the section, the abundance of calcareous turbidites, and the thin nature of the intercalated hemipelagic beds. Low content of badly preserved fossils and evidence of continuous and rapid sedimentation refer to alteration by tectonic disturbances or diagenesis. This makes the Baluti Beds as a supplementary section for the Rhaetian successions in Iraq.     

Distribution and facies patterns of Lower Cretaceous sediments in northern Germany: a review

Marine sediments of Early Cretaceous age (Berriasian–Albian) have a widespread distribution in the Lower Saxony Basin of northern Germany. This basin, which is about 400 km long and 100 km wide, formed the southernmost extension of the North Sea Basin. Sediments attaining a maximum thickness of up to several hundred metres are represented by shallow marine siliciclastics in the west, south and easternmost part of the basin. These interfinger with the basin facies represented by dark mudstones up to 2000 m thick. The distribution and facies patterns of the sediments as well as thicknesses are related to three factors: differential subsidence, local tectonics and sea-level changes. For various parts of the basin and certain stratigraphic intervals it is possible to distinguish between these causes. Sedimentary thicknesses are clearly a result of differential subsidence from Kimmeridgian to Albian times onwards, being controlled by tectonic movements along northwest–southeast trending faults. These result in an asymmetric trough, bound to the north and south by synsedimentary faults with sedimentation rates highest in the north. Local tectonics are clearly caused by salt diapirs mainly in the eastern part of the basin and along the western, southern and eastern margins. These areas in particular include parts of the western Emsland and the Salzgitter area. Sedimentary patterns vary considerably over less than a kilometre, showing an extreme range of different lithologies. This is ideally observed in the Salzgitter area. Sea-level changes finally are reflected by widespread facies patterns and particularly by fossils of different provenance. The following sea-level-related events can be followed throughout the basin: the Wealden regressive phase, the Early Valanginian transgression, the early Late Valanginian transgression, the mid Hauterivian transgression, the Barremian regression, deposition of the Early Aptian anoxic sediments, and accumulation of the mid Albian hemipelagic marls.     

Holocene sedimentation on the North Norfolk barrier coast in relation to relative sea-level change

Fourteen distinct sedimentary environments have been recognised in the surface sediments of the intertidal zone of the North Norfolk coast. Nine of these can be distinguished in borehole samples on the basis of sedimentological and micro-palaeontological characteristics. They comprise: gravel; channel sand; intertidal sand; intertidal silty sand; intertidal mud and marsh creek; lower salt marsh; upper salt marsh; dune sand; and peat. Sediment accumulations have been penetrated to a depth of ?8 m OD and basal peats dated by ¹⁴C back to 8410 ± 50 years BP. An overall rate of sediment accumulation (and subsidence) of about 1 m per thousand years is indicated. There is considerable persistence of sedimentary environments in the same areas during up-building, but some erosion and roll-over of the coastal barrier system has occurred. Evidence of positive and negative sea-level tendencies are present in the record, but the main development of the tract is determined by sediment supply to the beach and marshes; positive sea-level tendencies occur at c. 6610, 5970, 4630 and 2790 BP, negative sea-level tendencies occur at 4520 to 4450 and (possibly) 3470 BP.