Morphology, distribution and origin of recent submarine landslides of the Ligurian Margin (North-western Mediterranean): some insights into geohazard assessment

Based on new multibeam bathymetric data, seismic-reflection profiles and side-scan sonar images, a great number of submarine failures of various types and sizes was identified along the northern margin of the Ligurian Basin and characterized with 3 distinct end-members concerning their location on the margin, sedimentary processes and possible triggering mechanisms. They include superficial landslides mainly located in the vicinity of the main mountain-supplied rivers and on the inner walls of canyons (typically smaller that 10⁸ m³ in volume: Type 1), deep scars 100?C500 m high along the base of the continental slope (Type 2), and large-scale scars and Mass Transport Deposits (MTDs) affecting the upper part of the slope (Type 3 failures). The MTDs are located in different environmental contexts of the margin, including the deep Var Sedimentary Ridge (VSR) and the upper part of the continental slope in the Gulf of Genova (Finale Slide and Portofino Slide), with volumes of missing sediment reaching up to 1.5 × 10⁹ m³. High sedimentation rates related to hyperpycnal flows, faults and earthquake activity, together with sea-level fluctuations are the main factors invoked to explain the distribution and sizes of these different failure types.     

Spectroscopic evidence on organically-bound iron in natural and synthetic complexes with humic substances

On the basis of a lack of Mössbauer evidence and of a vague interpretation of some i.r. absorptions, Dicksonet al. (1979) conclude that no iron directly bound to humic materials persists after the usually accepted extraction and separation procedures. Many statements in the paper by Dicksonet al. (1979) appear to be contradictory with this conclusion.In this comment the author has tried to demonstrate that Mössbauer spectroscopy alone cannot give an answer to the problem, but needs further spectroscopic and chemical evidence. Mössbauer data, overinterpreted by Dicksonet al. (1979). have been critically discussed, in comparison with similar data previously obtained by various authors. Large spectroscopic—mainly Mössbauer, ESR and i.r.—evidence have been given in order to demonstrate the already well ascertained existence of organically bound iron in natural and synthetic complexes with humic substances.     

East-west trending magnetic anomalies in the Southern Hemisphere of Mars: Modeling analysis and interpretation

Maps of the vector components of the martian crustal magnetic field over the strongly magnetized Terra Cimmeria/Sirenum region are constructed using Mars Global Surveyor magnetometer data. Although pronounced east-west trending anomalies are present on the radial and north field component maps at the mapping altitude (∼360-380 km), these trends are much less prominent at the lower aerobraking altitude (∼90-150 km). Comparisons with similar maps produced using artificial data at the aerobraking altitude indicate that elongated sources in this region may have maximum lengths along the martian surface of ∼500 km and maximum aspect ratios of ∼2. Iterative forward modeling of several relatively isolated anomalies in the mapped region yields paleomagnetic pole positions consistent with those estimated in previous studies of other anomalies using mapping phase and science phasing orbit data. On this basis, it is inferred that sources in the studied region are most probably magnetized primarily in northward or southward directions. Using this additional constraint, iterative forward modeling is then applied to determine a magnetization distribution that is consistent with data at both the aerobraking altitude and the mapping altitude. The model magnetization distribution, which includes 41 discrete sources, again indicates no highly elongated sources. An examination of surface geology in the region as well as a consideration of the global distribution of anomalies suggests that magmatic intrusions (e.g., subsurface dike swarms), cooling in the presence of water, are the most likely sources of the magnetic anomalies.     

Stability at high pressure, elastic behavior and pressure-induced structural evolution of “Al5BO9”, a mullite-type ceramic material

Elastic behavior and pressure-induced structural evolution of synthetic boron-mullite “Al₅BO₉” (a = 5.678(2) Å, b = 15.015(4) Å and c = 7.700(3) Å, space group Cmc2₁, Z = 4) were investigated up to 7.4 GPa by in situ single-crystal X-ray diffraction with a diamond anvil cell under hydrostatic conditions. No phase transition or anomalous compressional behavior occurred within the investigated P range. Fitting the P–V data with a truncated second-order (in energy) Birch-Murnaghan Equation-of-State (BM-EoS), using the data weighted by the uncertainties in P and V, we obtained: V ₀ = 656.4(3) Å³ and K _T0 = 165(7) GPa (β _V0 = 0.0061(3) GPa^?1). The evolution of the Eulerian finite strain versus normalized stress (f _E–F _E plot) leads to an almost horizontal trend, showing that a truncated second-order BM-EoS is appropriate to describe the elastic behavior of “Al₅BO₉” within the investigated P range. The weighted linear regression through the data points gives: F _E(0) = 159(11) GPa. Axial compressibility coefficients yielded: β _a  = 1.4(2) × 10^?3 GPa^?1, β _b  = 3.4(4) × 10^?3 GPa^?1, and β _c  = 1.7(3) × 10^?3 GPa^?1 (β _a :β _b :β _c  = 1:2.43:1.21). The highest compressibilities observed in this study within (100) can be ascribed to the presence of voids represented by five-membered rings of polyhedra: Al1–Al3–Al4–Al1–Al3, which allow accommodating the effect of pressure by polyhedral tilting. Polyhedral tilting around the voids also explains the higher compressibility along [010] than along [001]. The stiffer crystallographic direction observed here might be controlled by the infinite chains of edge-sharing octahedra running along [100], which act as “pillars”, making the structure less compressible along the a-axis than along the b- and c-axis. Along [100], compression can only be accommodated by deformation of the edge-sharing octahedra (and/or by compression of the Al–O bond lengths), as no polyhedral tilting can occur. In addition, a comparative elastic analysis among the mullite-type materials is carried out.     

A method of determining optimum scales for averaging the earth's topography in quantitative studies of atmospheric cyclo- and anti-cyclogenesis

A method for optimum modelling of the earth's topography, corresponding to differing meteorological phenomena, is presented.The optimum averaging scale for mountains in terms of orographic cyclo- and anti-cyclogenesis is shown to be of the order of 150 km. The use of larger or smaller averaging scales decreases the correlation between the degree of cyclo- and anti-cyclogenesis and the parameters which describe the orography.A quantitative relation between orographic cyclo- and anti-cyclogenesis and the form of orography determined by the Laplacian ² Z ₀ of the terrain function Z ₀ = Z ₀(x, y) is presented.     

A multi-method approach for the identification and quantification of water balance components of two lentic small water bodies

The protection of the globally widespread lentic small water bodies (LSWB) must be based on detailed knowledge about their hydrological connectivity and water balance. The study aimed to identify and quantify water balance components as well as surface-groundwater interaction of two LSWB in a characteristic lowland region with a combination of different methods. This includes the collection of hydrological data and the use of bromide and water stable isotopes (δ²H and δ¹⁸O) as tracers. With their help, mixing models were established, and daily water balances were assessed. The results show a strong bidirectional interaction of both LSWB systems with shallow groundwater. Bromide and stable isotope tracers allowed for the identification of the most relevant in- and outflow sources and pathways. Thereby, isotope data revealed isotopic enrichment typical for open-water bodies and only minor precipitation inputs mainly relevant at the end of the dry season. Water balance calculations suggested accentuated seasonal dynamics that were strongly influenced by shallow groundwater, which represented large inputs into both LSWB. By that, different phases could be identified, with high inflow rates in winter and spring and decreasing fluxes in summer. In one LSWB, a drainage system was found to have a major impact next to the shallow groundwater interaction. The findings of this research provide detailed insights into the influence and importance of shallow groundwater for LSWB in lowland regions. This impacts the diffuse input of agricultural pollutants into these ecologically important landscape features.     

Alpine tectono‐metamorphic history of the continental units from Vardar zone: the Kopaonik Metamorphic Complex (Dinaric‐Hellenic belt,Serbia)

The easternmost zone of the Dinaric‐Hellenic belt is represented by the Vardar Zone, in which the Kopaonik Metamorphic Complex (KMC) is regarded as the lowermost unit. This complex is topped by the unmetamorphosed Brzece unit and is intruded by the Oligocene Kopaonik Intrusive complex. The KMC is characterized by a stratigraphy that includes metapelites and meta‐carbonates of Late Triassic age, associated with metabasites. It is characterized by a complex deformation history that comprises four phases: D1 to D4. The D1 phase structures occur only as relict structures, whereas the D2 phase structures are represented by isoclinal F2 folds, associated with a well‐developed S2 foliation. The estimated P‐T conditions for the D1 and D2 metamorphism are consistent with the upper greenschist facies. The D3 phase is characterized by west‐verging thrusts associated with upright folds. In contrast, the D4 phase is characterized by open folds (F4) associated with low‐angle normal faults. The D1 and D2 deformation phases developed during the shortening related to continental collision, whereas the subsequent D3 and D4 phases can be related to the progressive exhumation of the KMC. The D4 phase probably developed during extensional tectonics during and after emplacement of the Kopaonik Intrusive Complex. The data show that the continental units belonging to the Vardar zone had a long‐lived deformation history that was more complex that previously thought. Copyright © 2009 John Wiley & Sons, Ltd.     

FxJj43: A window into a 1.5‐million‐year‐old palaeolandscape in the Okote Member of the Koobi Fora Formation,northern Kenya

FxJj43 differs from most other archaeological sites preserved in the Okote Member of the Koobi Fora Formation in ways that make it especially suited to the problem of clarifying the behavioral information encapsulated in fine time‐lines. At this site in northern Kenya, a continuous strip of outcrops, preserving a set of interlocking landforms, can be traced around the modern erosion front for more than half a kilometer. The characteristics and three‐dimensional geometries of the beds making up these outcrops show that they have preserved the southern bank, levee, and floodplain of a westerly flowing sandy channel. Both stone tools and animal bones are strewn across the eroding surfaces of these outcrops, and excavations show that they are derived from a narrow stratigraphic horizon immediately overlying the volcanic ash at the base of the sequence. The blue tuff, and the archaeological horizon that overlies it, have been dated using the ⁴⁰Ar‐³⁹Ar method on single crystals of alkali feldspar. Although there is no direct measure of how long it took the archaeological horizon to accumulate, it probably accumulated over a time span of 10²–10³ years. Thus the locality may be used to test the proposition that the analysis of archaeological debris from fine‐time lines will help to resolve ambiguities in the interpretation of early Pleistocene archaeological assemblages. © 2002 Wiley Periodicals, Inc.     

Land cover change and soil organic carbon stocks in the Republic of Ireland 1851–2000

Using both historic records and CORINE land cover maps, we assessed the impact of land cover change on the stock of soil organic carbon (SOC) in the Republic of Ireland from 1851 to 2000. We identified ten principal land cover classes: arable land, forest, grassland, heterogeneous agricultural areas/other, nonvegetated semi-natural areas, peatland, suburban, urban, water bodies, and wetland. For each land cover class, the SOC stock was estimated as the product of SOC density and land cover area. These were summed to calculate a national SOC budget for the Republic of Ireland. The Republic of Ireland’s 6.94 million hectares of land have undergone considerable change over the past 150 years. The most striking feature is the decrease in arable land from 1.44 million ha in 1851 to 0.55 million ha in 2000. Over the same time period, forested land increased by 0.53 million ha. As of 2000, agricultural lands including arable land (7.85%), grassland (54.33%), and the heterogeneous agricultural areas/other class (7.91%) account for 70.09% of Irish land cover. We estimate that the SOC stock in the Republic of Ireland, to 1 m depth, has increased from 1,391 Tg in 1851 to 1,469 Tg in 2000 despite soil loss due to urbanization. This increase is largely due to the increase of forested land with its higher SOC stocks when compared to agricultural lands. Peatlands contain a disproportionate quantity of the SOC stock. Although peatlands only occupy 17.36% of the land area, as of 2000, they represented 36% of the SOC stock (to 1 m depth).