Analysis of syntectonic magmatic veins at the mesoscale

Syntectonic magmatic veins are useful tools to identify the interaction between magmatic and deformation processes in the lithosphere. They can be present at all crustal levels, scales and tectonic regimes. The structural analyses of sets of leucocratic veins and dykes from the Rainy Lake zone (Canada) and from Cap de Creus area (Spain), combined with the results of analogue deformation experiments, allows distinction between structures related to intrusion and emplacement, and structures related to post-emplacement deformation. This study also gives an insight on the influence of host rock rheology, regional thermal conditions and deformation history on the developed structures.     

Evaluation of stable iodine status of the areas affected by the Chernobyl accident in an epidemiological study in Belarus and the Russian Federation

Variation of the stable iodine supply was evaluated in the soils of around more than 700 settlements in the regions (oblasts) of Belarus and the Russian Federation contaminated after the Chernobyl accident. It involved the use of regional information on iodine content in different types of soil cover, biogeochemical criteria of iodine deficiency in food chains, and the available soil maps.     

Computation of Non-Maxwellian Electron Excitation Rates for Ions of Astrophysical Interest: Fe <Emphasis Type="SmallCaps">xv</Emphasis> – A Test Case

Dzif?áková previously developed a method for calculating the influence of nonthermal electron-velocity distributions on the intensities of spectral lines (Solar Phys. 234, 243, 2006; In: Lacoste, H., Ouwehand, L. (eds.) SOHO-17. 10 Years of SOHO and Beyond, SP-617, ESA, Noordwijk, 89, 2006). Here, we study this method in detail for the test case: Fe?xv. It involves fitting a parametric form to the electron-excitation data in the CHIANTI atomic database. We assess the reliability of these fits by comparing them with the source atomic data, both Upsilons (Maxwellian-averaged collision strengths) and the original collision strengths. An accuracy for the method of better than 15% is deduced for all transitions, with a much higher accuracy than this for the strong electric-dipole transitions. A κ-distribution, which has an increased number of electrons in the high-energy tail of the distribution, is considered as an example. The shape of the κ-distribution affects the electron-excitation rate and thus the relative intensities of the spectral lines. Since the shape of the electron distribution function also influences the ionization balance of Fe, both effects change the final intensities of the lines. Synthetic spectra for Fe?xv and Fe?xvi in the wavelength range 50?–?80 Å are presented for a κ-distribution and compared with solar observations.     

Connectance and stability of nonlinear symplectic systems

We have revisited the problem of the transition from ordered to chaotic motion for increasing number of degrees of freedom in nonlinear symplectic maps. Following the pioneer work of Froeschlé (Phys. Rev. A 18, 277–281, 1978) we investigate such systems as a function of the number of couplings among the equations of motion, i.e. as a function of a parameter called connectance since the seminal paper of Gardner and Ashby (Nature 228, 784, 1970) about linear systems. We compare two different models showing that in the nonlinear case the connectance has to be intended as the fraction of explicit dynamical couplings among degrees of freedom, rather than the fraction of non-zero elements in a given matrix. The chaoticity increases then with the connectance until the system is fully coupled.     

Rainfall retention and runoff generation processes in tropical mature green roof ecosystems

Rainfall retention and runoff detention are likely the most important ecosystem services provided by extensive green roofs (EGRs) that contribute to urban stormwater mitigation and management. However, the hydrological performance and runoff generation mechanisms of mature, well-established EGRs in tropical regions remain poorly understood. This study evaluated the rainfall retention, discharge detention times and processes of runoff generation in two neighbouring 20-year-old EGRs with different slopes (2° and 14° for EGRns and EGRws, respectively) and management practices in Mexico City; results were compared with those obtained in a conventional roof (CR, 2° slope). Precipitation, substrate moisture and storm runoff were continuously measured during the 2017 and 2018 rainy seasons (May–November). Results showed spatial differences in substrate properties and moisture within and between green roofs. In general, higher bulk densities and a wide range of variation in water content characterized the bare substrate areas compared to those below vegetation. Greatest increases in substrate moisture and storm runoff were observed in the steeper green roof. Subsurface flow was the dominant process controlling the amount and timing of stormflow in the EGRs. The occurrence of saturation excess overland flow was small and detected when large rain events were preceded by high wetness conditions. The main factors influencing the hydrological responses of the green roofs were their substrate hydrophysical properties, related mostly to vegetation cover, management and age, and to much lesser extent to slope and substrate depth. On average, rainfall retention was ~60% in the EGRs with significantly longer delays and prolonged runoff times (100 and 340 min, respectively) compared to CR (3%, 20 min, and 258 min, respectively). Overall, these findings highlight the potential of EGRs in reducing stormflow and peak discharges for most rainfall in Mexico City, and thus mitigating the risk of saturation and overflow of urban drainages.     

Speleothem-based chronology and environmental context of deposits from the Mishin Kamik Cave,NW Bulgaria – A contribution to the archaeological study of the Late Pleistocene human occupation in the Balkans

The Balkan Peninsula represents one of the most important human pathways into and out of Europe during the Pleistocene. Mishin Kamik cave, located in the karst region of Western Stara Planina, has a rich faunal content and shows promising features indicating a human occupation site with the discovery of potential bone artefacts and an intriguing accumulation of bear skulls and bones. Petrographic study and U-series dating of a stalagmite and other calcite deposits in the cave provide an absolute chronological frame for the detrital infillings and their archaeological content and inform the environmental and climatic context of the cave evolution. Most detrital deposits in the cave were probably deposited before Marine Isotope Stage (MIS) 5 and the cave morphology and sedimentary deposits display current morphologies since ~135 ka. Consequently, the palaeontological and archaeological findings are older than ~135 ka. Calcite dated on and under the accumulation of bear skulls and bones suggests deposition during MIS 7. A first depositional contextualization of the bone accumulation does not allow us to discriminate between a natural or anthropogenic origin. The study emphasizes the added value of speleothem studies in archaeological sites and particularly in bringing a well-constrained chronological and environmental framework.     

The last interglacial as represented in the glaciochemical record from Mount Moulton Blue Ice Area,West Antarctica

Understanding climate during the last interglacial is critical for understanding how modern climate change differs from purely naturally forced climate change. Here we present the first high-resolution ice core record of the last interglacial and transition to the subsequent glacial period from Antarctica and the first glaciochemical record for this period from West Antarctica. Samples were collected from a horizontal ice trench in the Mt. Moulton Blue Ice Area (BIA) in West Antarctica and analyzed for their soluble major anions (Cl^?, NO₃^?, SO₄^2-), major and trace elements (Na, Mg, Ca, Sr, Cd, Cs, Ba, La, Ce, Pr, Pb, Bi, U, As, Al, S, Ti, V, Cr, Mn, Fe, Co, Cu, Zn) and water hydrogen isotopes (δD). The last interglacial is characterized by warmer temperatures (δD), weakened atmospheric circulation (dust elements, seasalts aerosols), decreased sea ice extent (Na, nssSO₄^2-) and decreased oceanic productivity (nssSO₄^2-). A combined examination of Mt. Moulton seasalts, dust, nssSO₄^2- and δD records indicates that the last interglacial was extremely stable compared to glacial age climate events and it ended through a long period of gradual cooling unlike that projected for future Holocene climate.     

U–Pb,Lu–Hf and Sm–Nd isotopic constraints on provenance and depositional timing of metasedimentary rocks in the western Gawler Craton: Implications for Proterozoic reconstruction models

The Gawler Craton forms the bulk of the South Australian Craton and occupies a pivotal location that links rock systems in Antarctica to those in northern Australia. The western Gawler Craton is a virtually unexposed region where the timing of basin development and metamorphism is largely unknown, making the region ambiguous in the context of models seeking to reconstruct the Australian Proterozoic.Detrital zircon data from metasedimentary rocks in the central Fowler Domain in the western Gawler Craton provide maximum depositional ages between 1760 and 1700 Ma, with rare older detrital components ranging in age up to 3130 Ma. In the bulk of samples, ?_Nd(1700 Ma) values range between ?4.3 and ?3.8. The combination of these data suggest on average, comparatively evolved but age-restricted source regions. Lu–Hf isotopic data from the ca 1700 Ma aged zircons provide a wide range of values (?_Hf(1700 Ma) +6 to ?6). Monazite U–Pb data from granulite-grade metasedimentary rocks yield metamorphic ages of 1690–1670 Ma. This range overlaps with and extends the timing of the widespread Kimban Orogeny in the Gawler Craton, and provides minimum depositional age constraints, indicating that basin development immediately preceded medium to high grade metamorphism.The timing of Paleoproterozoic basin development and metamorphism in the western Gawler Craton coincides with that in the northern and eastern Gawler Craton, and also in the adjacent Curnamona Province, suggesting protoliths to the rocks within the Fowler Domain may have originally formed part of a large ca 1760–1700 Ma basin system in the southern Australian Proterozoic. Provenance characteristics between these basins are remarkably similar and point to the Arunta Region in the North Australian Craton as a potential source. In this context there is little support for tectonic reconstruction models that: (1) suggest components of the Gawler Craton accreted together at different stages in the interval ca 1760–1680 Ma; and (2) that the North Australian Craton and the southern Australian Proterozoic were separate continental fragments between 1760 and 1700 Ma.