Unravelling the enigmatic origin of calcitic nanofibres in soils and caves: purely physicochemical or biogenic processes?

Calcitic nanofibres are ubiquitous habits of sec- ondary calcium carbonate (CaCO3 ) accumulations observed in calcareous vadose environments. Despite their widespread occurrence, the origin of these nanofeatures remains enig- matic. Three possible mechanisms fuel the debate: (i) purely physicochemical processes, (ii) mineralization of rod-shaped bacteria, and (iii) crystal precipitation on organic templates. Nanofibres can be either mineral (calcitic) or organic in na- ture. They are very often observed in association with needle fibre calcite (NFC), another typical secondary CaCO3 habit in terrestrial environments. This association has contributed to some confusion between both habits, however they are truly two distinct calcitic features and their recurrent asso- ciation is likely to be an important fact to help understanding the origin of nanofibres. In this paper the different hypotheses that currently exist to explain the origin of calcitic nanofibres are critically reviewed. In addition to this, a new hypothe- sis for the origin of nanofibres is proposed based on the fact that current knowledge attributes a fungal origin to NFC. As this feature and nanofibres are recurrently observed together, a possible fungal origin for nanofibres which are associated with NFC is investigated. Sequential enzymatic digestion of the fungal cell wall of selected fungal species demonstrates that the fungal cell wall can be a source of organic nanofibres. The obtained organic nanofibres show a striking morpho- logical resemblance when compared to their natural coun- terparts, emphasizing a fungal origin for part of the organic nanofibres observed in association with NFC. It is further hy- pothesized that these organic nanofibres may act as templates for calcite nucleation in a biologically influenced mineraliza- tion process, generating calcitic nanofibres. This highlights the possible involvement of fungi in CaCO3 biomineraliza- tion processes, a role still poorly documented. Moreover, on a global scale, the organomineralization of organic nanofi- bres into calcitic nanofibres might be an overlooked process deserving more attention to specify its impact on the biogeo- chemical cycles of both Ca and C.

Geología del Montgrí

This paper, fundamentally stratigraphic, is based on the vertical distribution of fauna in sediments which constitute the Montgri Massif. The stratigraphic series is composed of two units: one allochtonous (Mesozoic) and a second one autochtonous (Paleogene). The latter crops out in front of the thrust belt and presents the typical facies described by PALLI (1972). The allochtonous part is formed by the following units (from bottom to top): variegated gypsiferous shales of Keuper age; marls, limestones and dolomites from the Lias (Domerian); gray breccia ted dolomites: supraliassic; and Cretaceous limestones with rare interbeds of calcareous marls and nodular shaly marls. In this unit the Neocomian, Barremian (?), Aptian, Albian, Cenomanian, Turonian (?) and Santonian haven been recognized. Structurally, the Montgri Massif is part of a thrust belt which has been divided into three parts of different development ang age. Both parts are affected by ample synclinal folds of NE-SW directions and fractures of NW-SE orientation. The fractures condition the torrential streams as well as the karstic phenomena present in the Massif. These and the eolian actions are the main causes of the present geomorphology of the Montgri

La paleolaguna de Otuma como potencial para la reconstrucción de las condiciones paleoceanográficas de Pisco.

Se describe la geomorfología del relieve de la paleolaguna de Otuma y se evalúa la preservación de sus registros calcáreos y su potencialidad para la reconstrucción paleoceanográfica y paleoecológica. Un pequeño acantilado marino y una plataforma de abrasión de suave pendiente con predominancia de arena y grava, sugieren un fondo submareal somero de 3,5 m de profundidad a 80 m de distancia de la orilla. La distribución de los registros calcáreos in situ, sobre el fondo de la paleolaguna sugiere un patrón de zonación ecológica. La abundancia de Argopecten purpuratus en los conchales demuestra su dominancia y la presencia de un antiguo y muy productivo banco natural de concha de abanico con una estructura de tallas 40 -140 mm. La preservación de las conchas permitió el análisis de sus anillos o líneas de crecimiento y la reconstruccion de sus ritmos y patrones de crecimiento que son valiosos para la reconstrucción de la variabilidad ambiental.

Potential impact of climate change on vegetation in the European Alps: a review

Based on conclusions drawn from general climatic impact assessment in mountain regions, the review synthesizes results relevant to the European Alps published mainly from 1994 onward in the fields of population genetics, ecophysiology, phenology, phytogeography, modeling, paleoecology and vegetation dynamics. Other important factors of global change interacting synergistically with climatic factors are also mentioned, such as atmospheric CO2 concentration, eutrophication, ozone or changes in land-use. Topics addressed are general species distribution and populations (persistence, acclimation, genetic variability, dispersal, fragmentation, plant/animal interaction, species richness, conservation), potential response of vegetation (ecotonal shift - area, physiography - changes in the composition, structural changes), phenology, growth and productivity, and landscape. In conclusion, the European Alps appear to have a natural inertia and thus to tolerate an increase of 1-2 K of mean air temperature as far as plant species and ecosystems are concerned in general. However, the impact of land-use is very likely to negate this buffer in many areas. For a change of the order of 3 K or more, profound changes may be expected.

Stratigraphic, sedimentological and palaeoenvironmental constraints on the rise of the Urgonian platform in the western Swiss Jura

Urgonian-type carbonates are a characteristic feature of many late Early Cretaceous shallow-marine, tropical and subtropical environments. The presence of typical photozoan carbonate-producing communities including corals and rudists indicates the prevalence of warm, transparent and presumably oligotrophic conditions in a period otherwise characterized by the high density of globally occurring anoxic episodes. Of particular interest, therefore, is the exploration of relationships between Urgonian platform growth and palaeoceanographic change. In the French and Swiss Jura Mountains, the onset and evolution of the Urgonian platform have been controversially dated, and a correlation with other, better dated, successions is correspondingly difficult. It is for this reason that the stratigraphy and sedimentology of a series of recently exposed sections (Eclepens, Vaumarcus and Neuchatel) and, in addition, the section of the Gorges de l'Areuse were analysed. Calcareous nannofossil biostratigraphy, the evolution of phosphorus contents of bulk rock, a sequence-stratigraphic interpretation and a correlation of drowning unconformities with better dated sections in the Helvetic Alps were used to constrain the age of the Urgonian platform. The sum of the data and field observations suggests the following evolution: during the Hauterivian, important outward and upward growth of a bioclastic and oolitic carbonate platform is documented in two sequences, separated by a phase of platform drowning during the late Early Hauterivian. Following these two phases of platform growth, a second drowning phase occurred during the latest Hauterivian and Early Barremian, which was accompanied by significant platform erosion and sediment reworking. The Late Barremian witnessed the renewed installation of a carbonate platform, which initiated with a phase of oolite production, and which progressively evolved into a typical Urgonian carbonate platform colonized by corals and rudists. This phase terminated at the latest in the middle Early Aptian, due to a further drowning event. The evolution of this particular platform segment is compatible with that of more distal and well-dated segments of the same northern Tethyan platform preserved in the Helvetic zone of the Alps and in the northern subalpine chains (Chartreuse and Vercors).

Impact of free-range pigs on mountain pastures in the Swiss Jura

The consequences of foraging by free-range pigs on the vegetation of mountain pastures was investigated. 25 pigs (15 week-old, mean weight 50 kg) were enclosed from June to mid-September in a 2 ha-enclosure in Jura Mountains (Switzerland), fed with a mixture of lactoserum and cereals. The enclosure contained five different plant communities. Eutrophic pastures on deep soil were strongly overturned, but the recolonisation was quick and dominated by the original species. Mesotrophic pastures were less damaged on stony soil but completely destroyed on deep soil, and the recovery was slow, characterised by a shift of plant species in a more eutrophic direction. Four years were not sufficient for complete recovery. Oligotrophic calcareous pastures on shallow stony soil were not damaged. Extensive breeding of pigs in mountain pastures might be harmful to plant species and vegetation, and ought to be restricted to the less sensitive plant communities, with a rotation on two to three different sites.

A unique Permian-Triassic boundary section from the Neotethyan Hawasina Basin, Central Oman Mountains

In the Wadi Wasit area (Central Oman Mountains), Dienerian breccias are widespread. These breccias consist mostly of Guadalupian reefal blocks, often dolomitised, and some rare small-sized blocks of lowermost Triassic bivalve-bearing limestones. A unique block, with a size of about 200 m(3), including Permian and earliest Triassic faunas has been studied in detail. The so-called Wadi Wasit block consists of three major lithological units. A basal unstratified grey limestone is rich in various reef-building organisms (rugose corals, calcareous sponges, stromatoporoids) and has been dated as Middle Permian. It is disconformably overlain by well- and thin-bedded light grey to yellowish coloured limestones rich in molluscs. Two major lithologies (Coquina Limestone respectively Bioclastic Limestone unit) characterise the shelly limestones, their contact seems gradual. These two units are well-dated; they are of Griesbachian age and contain three conodont zones, the Parvus Zone, the Staeschei Zone and the Sosioensis Zone, and two ammonoid zones, the Ophiceras tibeticum Zone and an 'unnamed interval'. The third unit consists of a grey marly limestone containing Neospathodus kummeli (basal Dienerian). It is the first record of well-dated basal Triassic sediments in the Arabian Peninsula. The Coquina Limestone is dominated by the bivalve Promyalina with some Claraia and Eumorphotis. This bivalve association is interpreted as a pioneering opportunistic assemblage. Towards the top of the Bioclastic Limestone unit, the faunal diversity increases and contains probably more than 20 taxa of bivalves, microgastropods, crinoids, brachiopods, ammonoids, echinoid spines, ostracods and conodonts. The generic diversity of this biofacies exceeds by far any other Griesbachian assemblage known. Our data give new evidence for the geodynamical history for the distal carbonate shelf bordering the Hawasina Basin. A break in the sedimentation characterises the Late Permian. The basal Triassic shows a steady transgression and the breccias may record a distinct gravitational collapse of platform margins linked with sea-level low stand at the end of Induan time (late Dienerian-basal Smithian). delta(13)C(carb) isotopic analyses were performed and yield typical Permian values of around 4parts per thousand for the Reefal Limestone, with a strong negative shift across the Permian-Triassic boundary. During the Griesbachian values shift positively from 0.5 to 3.1parts per thousand parallel to an increase in faunal diversity and probably primary productivity. The detailed faunal analysis and the discovery of an unexpected diversity give,us a new understanding of the recovery of the Early Triassic marine ecosystem.

Carbon isotope stratigraphy and carbonate production during the Early-Middle Jurassic: examples from the Umbria-Marche-Sabina Apennines (Central Italy)

The carbon isotopic signature of carbonates depends on secular variations of organic carbon and carbonate carbon production/burial rates. A decrease in carbonate productivity makes the organic/carbonate carbon ratio unstable up to the point that even minor variations in the organic carbon reservoirs can provoke carbon isotopic shifts. The delta(13)C positive shifts of the middle Carixian (early Pliensbachian) and the early Bajocian recorded in the Umbria-Marche-Sabina domain represent a good example of this mechanism. Both sedimentology and lithostratigraphy of pelagic platform-basin carbonate systems in this area show that important changes in the source of carbonates correspond to the observed isotopic shifts. The middle Carixian event is in fact well correlatable to the drastic reduction of benthic carbonate production on rift-related intrabasinal highs, which then became pelagic carbonate platforms. The early Bajocian event is concomitant with the beginning of a long hiatus on the pelagic carbonate platforms and with a drop of the biodiversity of calcareous organisms followed by the onset of biosiliceous sedimentation in basins. (C) 2002 Elsevier Science B.V. All rights reserved.

The role of fungi in the precipitation of calcite : relationships between fungal filaments, nanofibres, and needle fibre calcite

RésuméLes champignons sont impliqués dans les cycles biogéochimiques de différentes manières. En particulier, ils sont reconnus en tant qu'acteurs clés dans la dégradation de la matière organique, comme fournisseurs d'éléments nutritifs via l'altération des minéraux mais aussi comme grands producteurs d'acide oxalique et de complexes oxalo-métalliques. Toutefois, peu de choses sont connues quant à leur contribution à la genèse d'autres types de minéraux, tel que le carbonate de calcium (CaCO3). Le CaCO3 est un minéral ubiquiste dans de nombreux écosystèmes et il joue un rôle essentiel dans les cycles biogéochimiques du carbone (C) et du calcium (Ca). Le CaCO3 peut être d'origine physico-chimique ou biogénique et de nombreux organismes sont connus pour contrôler ou induire sa biominéralisation. Les champignons ont souvent été soupçonnés d'être impliqué dans ce processus, cependant il existe très peu d'informations pour étayer cette hypothèse.Cette thèse a eu pour but l'étude de cet aspect négligé de l'impact des champignons dans les cycles biogéochimiques, par l'exploration de leur implication potentielle dans la formation d'un type particulier de CaCO3 secondaires observés dans les sols et dans les grottes des environnements calcaires. Dans les grottes, ces dépôts sont appelés moonmilk, alors que dans les sols on les appelle calcite en aiguilles. Cependant ces deux descriptions correspondent en fait au même assemblage microscopique de deux habitus particulier de la calcite: la calcite en aiguilles (au sens strict du terme cette fois-ci) et les nanofibres. Ces deux éléments sont des habitus aciculaires de la calcite, mais présentent des dimensions différentes. Leur origine, physico-chimique ou biologique, est l'objet de débats intenses depuis plusieurs années déjà.L'observation d'échantillons environnementaux avec des techniques de microscopie (microscopie électronique et micromorphologie), ainsi que de la microanalyse EDX, ont démontré plusieurs relations intéressantes entre la calcite en aiguilles, les nanofibres et des éléments organiques. Premièrement, il est montré que les nanofibres peuvent être organiques ou minérales. Deuxièmement, la calcite en aiguilles et les nanofibres présentent de fortes analogies avec des structures hyphales, ce qui permet de confirmer l'hypothèse de leur origine fongique. En outre, des expériences en laboratoire ont confirmé l'origine fongique des nanofibres, par des digestions enzymatiques d'hyphes fongiques. En effet, des structures à base de nanofibres, similaires à celles observées dans des échantillons naturels, ont pu être produites par cette approche. Finalement, des enrichissements en calcium ont été mesurés dans les parois des hyphes et dans des inclusions intrahyphales provenant d'échantillons naturels de rhizomorphes. Ces résultats suggèrent une implication de la séquestration de calcium dans la formation de la calcite en aiguilles et/ou des nanofibres.Plusieurs aspects restent à élucider, en particulier la compréhension des processus physiologiques impliqués dans la nucléation de calcite dans les hyphes fongiques. Cependant, les résultats obtenus dans cette thèse ont permis de confirmer l'implication des champignons dans la formation de la calcite en aiguilles et des nanofibres. Ces découvertes sont d'une grande importance dans les cycles biogéochimiques puisqu'ils apportent de nouveaux éléments dans le cycle couplé C-Ca. Classiquement, les champignons sont considérés comme étant impliqués principalement dans la minéralisation de la matière organique et dans l'altération minérale. Cette étude démontre que les champignons doivent aussi être pris en compte en tant qu'agents majeurs de la genèse de minéraux, en particulier de CaCO3. Ceci représente une toute nouvelle perspective en géomycologie quant à la participation des champignons au cycle biologique du C. En effet, la présence de ces précipitations de CaCO3 secondaires représente un court-circuit dans le cycle biologique du C puisque du C inorganique du sol se retrouve piégé dans de la calcite plutôt que d'être retourné dans l'atmosphère.AbstractFungi are known to be involved in biogeochemical cycles in numerous ways. In particular, they are recognized as key players in organic matter recycling, as nutrient suppliers via mineral weathering, as well as large producers of oxalic acid and metal-oxalate. However, little is known about their contribution to the genesis of other types of minerals such as calcium carbonate (CaCO3). Yet, CaC03 are ubiquitous minerals in many ecosystems and play an essential role in the biogeochemical cycles of both carbon (C) and calcium (Ca). CaC03 may be physicochemical or biogenic in origin and numerous organisms have been recognized to control or induce calcite biomineralization. While fungi have often been suspected to be involved in this process, only scarce information support this hypothesis.This Ph.D. thesis aims at investigating this disregarded aspect of fungal impact on biogeochemical cycles by exploring their possible implication in the formation of a particular type of secondary CaC03 deposit ubiquitously observed in soils and caves from calcareous environments. In caves, these deposits are known as moonmilk, whereas in soils, they are known as Needle Fibre Calcite (NFC - sensu lato). However, they both correspond to the same microscopic assemblage of two distinct and unusual habits of calcite: NFC {sensu stricto) and nanofibres. Both features are acicular habits of calcite displaying different dimensions. Whether these habits are physicochemical or biogenic in origin has been under discussion for a long time.Observations of natural samples using microscopic techniques (electron microscopy and micromorphology) and EDX microanalyses have demonstrated several interesting relationships between NFC, nanofibres, and organic features. First, it has shown that nanofibres can be either organic or minera! in nature. Second, both nanofibres and NFC display strong structural analogies with fungal hyphal features, supporting their fungal origin. Furthermore, laboratory experiments have confirmed the fungal origin of nanofibres through an enzymatic digestion of fungal hyphae. Indeed, structures made of nanofibres with similar features as those observed in natural samples have been produced. Finally, calcium enrichments have been measured in both cell walls and intrahyphal inclusions of hyphae from rhizomorphs sampled in the natural environment. These results point out an involvement of calcium sequestration in nanofibres and/or NFC genesis.Several aspects need further investigation, in particular the understanding of the physiological processes involved in hyphal calcite nucleation. However, the results obtained during this study have allowed the confirmation of the implication of fungi in the formation of both NFC and nanofibres. These findings are of great importance regarding global biogeochemical cycles as they bring new insights into the coupled C and Ca cycles. Conventionally, fungi are considered to be involved in organic matter mineralization and mineral weathering. In this study, we demonstrate that they must also be considered as major agents in mineral genesis, in particular CaC03. This is a completely new perspective in geomycology regarding the role of fungi in the short-term (or biological) C cycle. Indeed, the presence of these secondary CaC03 precipitations represents a bypass in the short- term carbon cycle, as soil inorganic C is not readily returned to the atmosphere.

Circum-Alpine marine circulation and paleoenvironmental conditions during the Miocene

Trace element and isotopic compositions of marine fossils and sediment were analyzed from several Miocene deposits in the circum-Alpine region in order to reconstruct the paleoceanographic and paleoclimatic changes related to sea level changes, basin evolution and Alpine orogeny. To the north and the east the Alps were border by an epicontinental sea, the Paratethys, while to the south the Mediterranean surrounded the uplifting mountains during the Miocene. The thesis mainly focused on sediments and fossils sampled from Miocene beds of these two oceanic provinces. The north Alpine Molasse, the Vienna and Pannonian Basins were located in the Western and Central Paratethys. O-isotope compositions of well-preserved phosphatic fossils in these sediments support deposition under sub-tropical to warm-temperate climate with water temperatures between 14 to 28 °C for the Miocene. δ18O values of fossil shark teeth from different horizons vary similarly to those of the global trend until the end of the Badenian, however the δ18O values show wider range, which indicates local effects iii the sub-basins. The trend of 87Sr/86Sr in the samples roughly agrees with an open ocean environment for the Miocene. Yet a number of samples deviate from typical open ocean compositions with higher ratios suggesting modification of seawater by local and old terrestrial sources. In contrast, two exceptional teeth from the locality of La Moliere have extremely low δ18O values and low 87Sr/86Sr. However, the REE patterns of their enameloid are similar to those of teeth having O and Sr isotopic compositions typical of a marine setting at this site. Collectively, this suggests that the two teeth formed while the sharks frequented a freshwater environment with very low 18O-content and 87Sr/86Sr controlled by Mesozoic calcareous rocks. This is consistent with a paleogeography of high-elevation (~2300m) Miocene Alps adjacent to a marginal sea. The local effects are also reflected in the εNd values of the Paratethyan fossils, which is compatible with input from ancient crystalline rocks and Mesozoic sediments, while other samples with elevated εNd values indicate an influence of Neogene volcanism on the water budget. Excluding samples whose isotopic compositions reflect a local influence on the water column, an average εNd value of -7.9 ± 0.5 may be inferred for the Paratethys seawater. This value is indistinguishable from the Miocene value of the Indian Ocean, supporting a dominant role of ludo-Pacific water masses in the Paratethys. Regarding the Mediterranean, stable C-and O-isotope compositions of benthic and planktonic foraminifera from the Umbria-Marche region (UMC) have an offset typical for their habitats and the changes in composition mimic global changes, suggesting that the regional conditions of climate and the carbon cycle were controlled by global changes. The radiogenic isotope compositions of the fossil assemblages allow for distinction of periods. From 25 to 19 Ma, high εNd values and low 87Sr/86Sr of sediments and fossils support intense tectonism and volcanism, related to the opening of the western Mediterranean. Between 19 and 13 Ma the Mediterranean has εNd values that are largely controlled by incursion of Indian Ocean water. Brief periods of local hinterland control on seawater compositions are indicated by spikes in the εNd record, coinciding with volcanic events and a short sea-level decrease at about 15.2 Ma. Lower 87Sr/86Sr compared to the open ocean is compatible with rapid uplift of the hinterland and intense influx of Sr from Mesozoic carbonates of the western Apennines, while higher 87Sr/86Sr for other sites indicates erosion of old crustal silicate rocks. Finally, from 13 to 7 Ma the fossils have 87Sr/86Sr similar to those of Miocene seawater and their εNd values indicates fluctuating influence of Atlantic, and Indian Ocean or Paratethys sources of seawater entering the Mediterranean, driven by global sealevel changes and local tectonism. RÉSUMÉ DE LA THÈSE Les compositions en éléments traces et isotopiques de fossiles marins et de sédiments on été analysées à partir de nombreux dépôts marins dans la région circum Alpine dans le but de reconstruire les changements paléocéanographiques et paléoclimatiques liés aux changements du niveau marin, à l'évolution en bassins et à l'orogénie alpine. Au nord et à l'est des Alpes, une mer épicontinentale appelée Paratéthys s'est ouverte, alors que plus au sud la mer Méditerranée bordait au Miocène les Alpes naissantes. Le but de cette recherche est de se concentrer sur les sédiments et les fossiles provenant des couches du Miocènes de ces deux provinces marines. Les bassins de la Molasse Alpine du nord, de Vienne et Pannonien étaient situés au niveau de la Paratéthys Occidentale et Centrale. Les compositions isotopiques de l'oxygène de fossiles phosphatés bien préservés dans ces sédiments étayent la théorie d'un dépôt sous un climat subtropical à tempéré chaud avec des températures entre 14 et 28°C pendant le Miocène. Les valeurs δ18O des fossiles sont similaires à la tendance globale jusqu'à la fin du Badénien. Cependant les larges fluctuations en δ18O indiquent des effets locaux au niveau des sous bassins. En outre, deux dents de requin exceptionnelles présentent des valeurs extrêmement basses de δ18O. Ces données suggèrent que ces deux dents se sont formées alors que les requins fréquentaient un environnement d'eau douce avec de faibles valeurs de 18O. Le calcul de la composition isotopique de l'oxygène de cette eau douce permet d'obtenir une estimation de la paléoélévatian moyenne des Alpes du Miocène (~2300m). La tendance 87Sr/86Sr pour ces échantillons concorde approximativement avec un environnement d'océan ouvert au cours du Miocène. Toutefois un nombre d'échantillons dévie des compositions d'océan ouvert typiques, avec des rapports élevés suggérant des modifications de l'eau de mer par des sources locales et terrestres. Les effets locaux sont aussi reflétés au niveau des valeurs en εNd des fossiles paratéthysiens. Ceci est cohérent avec un apport d'anciennes roches cristallines et de sédiments mésozoïques, tandis que d'autres échantillons avec des valeurs hautes de εNd indiquent une influence d'un volcanisme néogène dans le budget marin. En excluant les échantillons dont les compositions isotopiques confirment une influence locale, une valeur moyenne de εNd de 7.9 t 0.5 peut être déduite pour l'eau de la Parathétys. Cette valeur est semblable à la valeur correspondant à l'Océan Indien durant le Miocène, confirmant un rôle dominant de cet océan dans la Paratéthys. Au niveau de la Méditerranée, les compositions en isotopes stables du Carbone et de l'Oxygène de foraminifères planctoniques et benthique de la région Umbria-Marche présentent un offset typique à leurs habitats. De plus les changements dans leurs compositions suivent les changements globaux, suggérant ainsi que les conditions climatiques régionales et le cycle du carbone étaient contrôlés par des phénomènes globaux. La composition en isotopes radiogéniques d'assemblages fossiles permet une reconnaissance sur trois périodes distinctes. De 25 à 19 millions d'années (Ma), des valeurs élevées de εNd et un faible rapport 87Sr/86Sr dans les sédiments soutiennent l'idée d'une activité tectonique et volcanique intense, liée à l'ouverture de la Méditerranée occidentale. Entre 19 et 13 Ma, la Méditerranée montre des valeurs de εNd qui sont largement contrôlées par une incursion d'eau provenant de l'Océan Indien. En effet, aux alentours de 15,2 Ma, des pics dans l'enregistrement des valeurs de εNd, coïncidant avec des événements volcaniques et de brèves diminutions du niveau marin. Enfin, de 13 à 7 Ma, les fossiles ont des rapports ß7Sr/8fiSr similaires à ceux de l'eau de mer au Miocène. Leurs valeurs de εNd indiquent une influence changeante de l'océan Atlantique, et de l'océan Indien ou des sources d'eau de merde la Parathétys qui entrent dans les bassins méditerranéens. Ce changement est guidé par des modifications globales du niveau marin et par la tectonique locale. RÉSUMÉ DE LA THÈSE (POUR LE GRAND PUBLIC) Les analyses des compositions en éléments traces et isotopiques des fossiles marins sont un outil très utile pour reconstruire les conditions océaniques et climatiques anciennes. Ce travail de thèse se concentre sur les sédiments déposés dans un environnement marin proches des Alpes au cours du Miocène, entre 23 et 7 millions d'années (Ma). Cette période est caractérisée par une tectonique alpine active, ainsi que par des changements climatiques et océanographiques globaux importants. Dans le but de tracer ces changements, les compositions isotopiques du Strontium, du Néodyme, de l'Oxygène et du Carbone ont été analysées dans des fossiles bien préservés ainsi que les sédiments contemporains. Les échantillons proviennent de deux provinces océaniques distinctes, la première est la Mer Méditerranée, et l'autre est une mer épicontinentale appelée Parathétys, qui existait au nord et à l'est des Alpes durant le Miocène. Au niveau de la Parathétys Occidentale et Orientale, les compositions isotopiques d'oxygène de dents de requins confirment un dépôt sous un climat subtropical à tempéré chaud avec des températures d'eau entre 14 et 28°C au Miocène. En outre, deux dents de requins exceptionnelles ont enregistré des compositions isotopiques d'oxygène extrêmement basses. Cela suggère que ces deux dents se sont formées alors que les requins entraient dans un système d'eau douce. Le calcul de la composition isotopique de l'oxygène de cette eau douce permet d'obtenir une estimation de la paléoélévation des Alpes au Miocène qui est aussi élevée que celle d'aujourd'hui. La tendance isotopique du Strontium pour ces échantillons concorde approximativement avec un environnement d'océan ouvert. Cependant un certain nombre d'échantillons indique des modifications de l'eau de mer par des sources terrestres locales. Les effets locaux sont aussi visibles au niveau des compositions isotopiques du Néodyme, qui sont en accord avec un apport provenant de roches cristallines anciennes et de sédiments du Mésozoïque, alors que d'autres échantillons indiquent une influence volcanique néogène dans le budget marin. A l'exclusion des échantillons dont les compositions correspondent à une influence locale, les compositions isotopiques du Néodyme de la Parathétys sont très similaires aux valeurs de l'Océan Indien, montrant ainsi un rôle important des masses d'eau IndoPacifiques dans cette région. Au niveau de la Méditerranée, les compositions en isotopes stables du Carbone et de l'Oxygène de foraminifères planctoniques et benthique de la région Umbria-Marche présentent un offset typique à leurs habitats. De plus, les changements dans leurs compositions suivent les changements globaux, suggérant ainsi que les conditions climatiques régionales et le cycle du carbone étaient contrôlés par des phénomènes globaux. La composition en isotopes radiogéniques d'assemblages fossiles permet une reconnaissance sur trois périodes distinctes. De 25 à 19 Ma, des rapport isotopiques élevés pour le Néodyme et faibles pour le Strontium dans les sédiments et les fossiles soutiennent l'idée d'une activité tectonique et volcanique intense, liée à l'ouverture de la Méditerranée occidentale. Entre 19 et 13 Ma, la Méditerranée présente des rapports isotopiques du Néodyme qui sont largement contrôlés par une incursion d'eau provenant de l'Océan Indien. En effet, aux alentours de 15,2 Ma, des pics dans l'enregistrement des valeurs des isotopes du Néodyme coïncident avec des événements volcaniques et de brèves diminutions du niveau marin. Finalement, de 13 à 7 Ma, les fossiles ont des rapports isotope Strontium similaires à ceux de l'eau de mer au Miocène. Les rapports isotopiques du Néodyme indiquent une influence changeante de l'océan Atlantique, et de l'océan Indien ou des sources d'eau de mer de la Parathétys qui entrent dans les bassins méditerranéens. Ce changement est guidé par des modifications globales du niveau marin et par la tectonique locale.

Clay mineral and geochemical composition of Cenozoic paleosol in the Eastern Alps (Austria)

Red clays from Cenozoic palaeosols of the Eastern Alps record periods of stagnating uplift and decrease of relief. Tropical to sub-tropical weathering of a crystalline substratum formed dominant or abundant kaolinite, reflecting Paleogene and Early Miocene conditions, respectively. Abundant illite and chlorite, but a lack of kaolinite in red clays on the plateaus of the Northern Calcareous Alps reflects feldspar-poor compositons of the Cenozoic siliciclastic cover. The presence of high Ba/Sr and Rb/Sr ratios and vermiculite in these red clays indicates high precipitation and temperate weathering conditions, respectively, during the Late Miocene and Early Pilocene on the uplifting plateaus of the Northern Calcareous Alps.

The ecological significance of arbuscular mycorrhizal fungal effects on clonal reproduction in plants

The population ecology of clonal plants depends on the number and distribution of ramets formed during growth. Variation in clonal reproduction has previously been explained by variation in effects of abiotic resource heterogeneity and by plant genotypic variation. Different co-occurring species of the mutualistic arbuscular mycorrhizal fungi (AMF) have been shown to differentially alter growth traits of Prunella vulgaris which we hypothesize would lead to changes in clonal reproduction. Two experiments were carried out to test whether different co-occurring mycorrhizal fungi significantly influence clonal reproduction of P. vulgaris whether this effect also occurs when P. vulgaris is growing in an artificial plant community and how the effects compare with plant genotype effects on clonal growth of P. vulgaris. In the first experiment the number of ramets of P. vulgaris growing in a plant community of simulated calcareous grassland was significantly affected by inoculation with different mycorrhizal fungi. The number of ramets produced by P. vulgaris differed by a factor of up to 1.8 with different mycorrhizal fungi. The fungal effects on the number of new ramets were independent of their effects on the biomass of P. vulgaris. In a second experiment 17 different genotypes of P. vulgaris were inoculated with different mycorrhizal fungi. There were significant main effects of genotypes and mycorrhizal fungi on clonal reproduction of P. vulgaris. The effect of different mycorrhizal fungi contributed more than the effect of plant genotype to variation in size and ramet production. However mean stolon length and spacer length which determine the spatial arrangement of ramets were only significantly affected by plant genotype. There were no mycorrhizal fungal X plant genotype interactions on clonal growth of P. vulgaris indicating that there is no obvious evidence that selection pressures would favor further coevolution between P. vulgaris and mycorrhizal fungal species. In natural communities plants can be colonized by several different AMF at the same time. The effect of the mixed AMF treatment on the growth and clonal reproduction of P. vulgaris could not be predicted from the responses of the plants to the single AMF To what extent however the patterns of colonization by different AMF differ among plants in a natural community is unknown. Since the effects of AMF on growth and clonal reproduction occur on a population of P. vulgaris in a microcosm plant community and because the effects are also as great as those caused by plant genotypic variation we conclude that the effects are strong enough to potentially affect population size and variation of clonal plants in communities.

Evaluating Roadway Subsurface Drainage Practices, 2013

The bearing capacity and service life of a pavement is affected adversely by the presence of undrained water in the pavement layers. In cold winter climates like in Iowa, this problem is magnified further by the risk of frost damage when water is present. Therefore, well-performing subsurface drainage systems form an important aspect of pavement design by the Iowa Department of Transportation (DOT). However, controversial findings are also reported in the literature regarding the benefits of subsurface drainage. The goal of this research was not to investigate whether subdrains are needed in Iowa pavements, but to conduct an extensive performance review of primary interstate pavement subdrains in Iowa, determine the cause of the problem if there are drains that are not functioning properly, and investigate the effect of poor subdrain performance due to improper design, construction, and maintenance on pavement surface distresses, if any. An extensive literature review was performed covering national-level and state-level research studies mainly focusing on the effects of subsurface drainage on performance of asphalt and concrete pavements. Several studies concerning the effects of a recycled portland cement concrete (RPCC) subbase on PCC pavement drainage systems were also reviewed. A detailed forensic test plan was developed in consultation with the project technical advisory committee (TAC) for inspecting and evaluating the Iowa pavement subdrains. Field investigations were conducted on 64 selected (jointed plain concrete pavement/JPCP and hot-mix asphalt/HMA) pavement sites during the fall season of 2012 and were mainly focused on the drainage outlet conditions. Statistical analysis was conducted on the compiled data from field investigations to further investigate the effect of drainage on pavement performance. Most Iowa subsurface drainage system outlet blockage is due to tufa, sediment, and soil. Although higher blockage rates reduce the flow rate of water inside outlet pipes, it does not always stop water flowing from inside the outlet pipe to outside the outlet pipe unless the outlet is completely blocked. Few pavement surface distresses were observed near blocked subsurface drainage outlet spots. More shoulder distresses (shoulder drop or cracking) were observed near blocked drainage outlet spots compared to open ones. Both field observations and limited performance analysis indicate that drainage outlet conditions do not have a significant effect on pavement performance. The use of RPCC subbase in PCC pavements results in tufa formation, a primary cause of drainage outlet blockage in JPCP. Several useful recommendations to potentially improve Iowa subdrain performance, which warrant detailed field investigations, were made

Evaluating Roadway Subsurface Drainage Practices: Tech Transfer Summary, 2013.

The bearing capacity and service life of a pavement is affected adversely by the presence of undrained water in the pavement layers. In cold winter climates like in Iowa, this problem is magnified further by the risk of frost damage when water is present. Therefore, well-performing subsurface drainage systems form an important aspect of pavement design by the Iowa Department of Transportation (DOT). However, controversial findings are also reported in the literature regarding the benefits of subsurface drainage. The goal of this research was not to investigate whether subdrains are needed in Iowa pavements, but to conduct an extensive performance review of primary interstate pavement subdrains in Iowa, determine the cause of the problem if there are drains that are not functioning properly, and investigate the effect of poor subdrain performance due to improper design, construction, and maintenance on pavement surface distresses, if any. An extensive literature review was performed covering national-level and state-level research studies mainly focusing on the effects of subsurface drainage on performance of asphalt and concrete pavements. Several studies concerning the effects of a recycled portland cement concrete (RPCC) subbase on PCC pavement drainage systems were also reviewed. A detailed forensic test plan was developed in consultation with the project technical advisory committee (TAC) for inspecting and evaluating the Iowa pavement subdrains. Field investigations were conducted on 64 selected (jointed plain concrete pavement/JPCP and hot-mix asphalt/HMA) pavement sites during the fall season of 2012 and were mainly focused on the drainage outlet conditions. Statistical analysis was conducted on the compiled data from field investigations to further investigate the effect of drainage on pavement performance. Most Iowa subsurface drainage system outlet blockage is due to tufa, sediment, and soil. Although higher blockage rates reduce the flow rate of water inside outlet pipes, it does not always stop water flowing from inside the outlet pipe to outside the outlet pipe unless the outlet is completely blocked. Few pavement surface distresses were observed near blocked subsurface drainage outlet spots. More shoulder distresses (shoulder drop or cracking) were observed near blocked drainage outlet spots compared to open ones. Both field observations and limited performance analysis indicate that drainage outlet conditions do not have a significant effect on pavement performance. The use of RPCC subbase in PCC pavements results in tufa formation, a primary cause of drainage outlet blockage in JPCP. Several useful recommendations to potentially improve Iowa subdrain performance, which warrant detailed field investigations, were made.

Analcime crystallization and compositional profiles - Comparing approaches to detect post-depositional alterations in archaeological pottery

The approaches of comparative studies and profile measurements, often used in order to detect post-depositional alterations of ceramics, have been applied simultaneously to two sets of Roman pottery, both of which include altered individuals. As analytical techniques, Neutron Activation Analysis and X-Ray Diffraction have been used. Both approaches lead to substantially different results. This shows that they detect different levels of alteration and should complement each other rather than being used exclusively. For the special process of a glassy phase decomposition followed by a crystallization of the Na-zeolite analcime, the results suggest that it changes high-fired calcareous pottery rapidly, and so fundamentally that the results of various archaeometric techniques can be severely disturbed.