Dust deposition and climate in the Carpathian Basin over an independently dated last glacial–interglacial cycle

Loess in the Carpathian Basin is some of the thickest and most complete in Europe. Located in the Vojvodina region of the southern Carpathian Basin the Crvenka loess-palaeosol section appears to preserve a detailed climate proxy archive of the last glacial–interglacial cycle. Central to the interpretation of the site is a detailed and independent age model. Here, the results of detailed optically stimulated luminescence (OSL) dating and elevated temperature post-IR infrared stimulated luminescence (post-IR IRSL) dating are presented. Quartz OSL ages appear accurate to about 50–60 ka, where 2D₀ values are reached, while elevated temperature post-IR IRSL yields more accurate ages below this. In line with recent results, the latter signal appears to show negligible fading rates. Two age models are developed that combine (a) OSL and post-IR IRSL ages and (b) OSL ages and ‘expected’ ages from tying unit boundaries to the marine record. If the luminescence model is regarded as accurate, differences between this and the OSL/marine age model raise questions over the accuracy of the latter, as well as the processes controlling the zeroing of luminescence dates. The luminescence based age model is then used to derive the first fully independent reconstruction of climate proxies and accumulation rates from Carpathian loess. Such reconstructions can be used to compare to other independent records without assumptions inherent in correlation-based approaches. The findings demonstrate how variable accumulation rate is at the site, and compared to other independently dated Carpathian loess records. Average values vary north–south but are of similar order throughout the basin. Accumulation rate was highest during the later part of the last glacial, but variation on millennial timescales does not always match shifts in grain-size, suggesting diverse and complex influences. Environmental reconstructions using grain-size and magnetic susceptibility show that no one atmospheric system or air mass can explain the changes in the Carpathian Basin and that millennial-scale variability can only intermittently be tied to North Atlantic Heinrich events. Expanded ice sheets during the peak last glacial, combined with other atmospheric teleconnections, may have served to develop a strong anticyclone in the region. It was likely windier during earlier parts of the last glacial, but Atlantic and Mediterranean moisture was probably less abundant than during more humid interglacials.     

The role of climate in the spread of modern humans into Europe

The spread of anatomically modern humans (AMH) into Europe occurred when shifts in the North Atlantic meridional overturning circulation triggered a series of large and abrupt climate changes during the last glacial. However, the role of climate forcing in this process has remained unclear. Here we present a last glacial record that provides insight into climate-related environmental shifts in the eastern Mediterranean region, i.e. the gateway for the colonisation of Europe by AMH. We show that the environmental impact of the Heinrich Event H5 climatic deterioration c. 48 kyr ago was as extreme as that of the glacial maximum of Marine Isotope Stage (MIS) 4 when most of Europe was deserted by Neanderthals. We argue that Heinrich H5 resulted in a similar demographic vacuum so that invasive AMH populations had the opportunity to spread into Europe and occupy large parts before the Neanderthals were able to reoccupy this territory. This spread followed the resumption of the Atlantic meridional overturning circulation at the beginning of Greenland Interstadial (GIS) 12 c. 47 kyr ago that triggered an extreme and rapid shift from desert-steppe to open woodland biomes in the gateway to Europe. We conclude that the extreme environmental impact of Heinrich H5 within a situation of competitive exclusion between two closely related hominids species shifted the balance in favour of modern humans.     

Ion tracks in apatite at high pressures: the effect of crystallographic track orientation on the elastic properties of fluorapatite under hydrostatic compression

Static elasticity measurements at high pressures were carried out on oriented fluorapatite single crystals, some of which contained oriented amorphous ion tracks (ITs) implanted with relativistic Au ions (2.2 GeV) from the UNILAC linear accelerator at GSI, Darmstadt. High-pressure experiments on irradiated and non-irradiated crystal sections were carried out in diamond-anvil high-pressure cells under hydrostatic conditions. In situ single-crystal diffraction was performed to determine the high-precision lattice parameters, simultaneously monitoring the widths of X-ray diffraction Bragg peaks. High-pressure Raman spectra were analyzed with respect to the frequency shift and widths of bands, which correspond to the Raman-active vibrational modes of the phosphate tetrahedra. Swift heavy ion irradiation was found to induce anisotropic lattice expansion and tensile strain within the host lattice dependent on the ion-track orientation. The relatively low Grüneisen parameter for the ν _1b(A _g) mode, which has been assigned to originate from the volume fraction of the amorphous tracks, and the γ(ν _1a)/γ(ν _1b) ratio reveals compressive strain on the amorphous ITs. The comparative compressibilities for the host lattice reveal approximately equivalent bulk moduli, but significantly different pressure derivatives (K _T = 88.4 ± 0.7 GPa, ∂K/∂P = 6.3 ± 0.3 for non-irradiated, K _T = 90.0 ± 1.7 GPa, ∂K/∂P = 3.8 ± 0.5 for irradiated samples). The axial compressibility moduli β ⁻¹ reveal significant differences, which correlate with the ion-track orientation [b_a ^{- 1} \beta_{a}^{ - 1}  = 240 ± 5 GPa, b_c ^{- 1} \beta_{c}^{ - 1}  = 361 ± 14 GPa, ∂( b_a ^{- 1} ) \left( {\beta_{a}^{ - 1} } \right) /∂P = 11.3 ± 1.2, ∂( b_c ^{- 1} ) \left( {\beta_{c}^{ - 1} } \right) /∂P = 11.6 ± 3.4 for irradiation ⊥(100); 246 ± 9 GPa, 364 ± 57 GPa, 9.5 ± 2.9, 14.7 ± 14.1 for irradiation ⊥(001), 230.7 ± 3.6 GPa, 373.5 ± 5.1 GPa, 19.2 ± 1.4, 20.1 ± 1.8 for no irradiation]. Line widths of XRD Bragg peaks in irradiated apatites confirm the strain of the host lattice, which appears to decrease with increasing pressure. By contrast, the bandwidths of Raman modes increase with pressure, and this is attributed to increasing strain gradients on the length scale of the short-range order. The investigations reveal considerable deviatoric stress on the [100]-oriented tracks due to the anisotropic elasticity, while the compression is uniform for the directions perpendicular to the tracks, which are aligned parallel to the c-axis. This difference might be considered to control the diffusion properties related to the annealing kinetics and its observed anisotropy, and hence to cause potential pressure effects on track-fading rates.     

Stereo analysis of high-resolution SAR images for building height estimation in cases of orthogonal aspect directions

SAR stereo image analysis for 3D information extraction is mostly carried out based on imagery taken under same-side or opposite-side viewing conditions. For urban scenes in practice stereo is up to now usually restricted to the first configuration, because increasing image dissimilarity connected with rising illumination direction differences leads to a lack of suitable features for matching, especially in the case of low or medium resolution data. However, due to two developments SAR stereo from arbitrary viewing conditions becomes an interesting option for urban information extraction. The first one is the availability of airborne sensor systems, which are capable of more flexible data acquisition in comparison to satellite sensors. This flexibility enables multi-aspect analysis of objects in built-up areas for various kinds of purpose, such as building recognition, road network extraction, or traffic monitoring. The second development is the significant improvement of the geometric resolution providing a high level of detail especially of roof features, which can be observed from a wide span of viewpoints. In this paper, high-resolution SAR images of an urban scene are analyzed in order to infer buildings and their height from the different layover effects in views taken from orthogonal aspect angles. High level object matching is proposed that relies on symbolic data, representing suitable features of urban objects. Here, a knowledge-based approach is applied, which is realized by a production system that codes a set of suitable principles of perceptual grouping in its production rules. The images are analyzed separately for the presence of certain object groups and their characteristics frequently appearing on buildings, such as salient rows of point targets, rectangular structures or symmetries. The stereo analysis is then accomplished by means of productions that combine and match these 2D image objects and infer their height by 3D clustering. The approach is tested using real SAR data of an urban scene.     

Diverse protolith ages for the Mindoro and Romblon Metamorphics (Philippines): Evidence from single zircon U–Pb dating

Within the north‐eastern part of the Palawan Continental Terrane, which forms the south‐western part of the Philippine archipelago, several metamorphic complexes are exposed that are considered to be rifted parts of the Asian margin in South‐East China. The protolith age(s) and correlations of these complexes are contentious. The largest metamorphic complex of the Palawan Continental Terrane comprises the Mindoro Metamorphics. The north‐eastern part of this metamorphic complex has recently been found to be composed of protoliths of Late Carboniferous to Late Permian protolith age. However, meta‐sediments exposed at the westernmost tip and close to the southern boundary of the exposure of the Mindoro Metamorphics contain detrital zircons and with U–Pb ages, determined by LA–ICP–MS, in the range 22–56 Ma. In addition, zircons as young as 112 Ma were found in a sample of the Romblon Metamorphics in Tablas. As the youngest detrital zircons provide an upper age limit for the time of deposition in meta‐sediments, these results suggest that the Mindoro and Romblon Metamorphics comprise protoliths of variable age: Late Carboniferous to Late Permian in NE Mindoro; Eocene or later in NW Mindoro; Miocene at the southern margin of the Mindoro metamorphics; and Cretaceous or later on Tablas. The presence of non‐metamorphic sediments of Late Eocene to Early Oligocene age in Mindoro (Lasala Formation), which are older than the youngest metasediments, suggests that metamorphism of the young meta‐sediments of Mindoro is the result of the collision of the Palawan Continental terrane with the Philippine Mobile Belt in Late Miocene. Similarities of the age spectra of zircons from the Eocene to Miocene metamorphics with the Eocene to Early Miocene Lasala Formation suggest that the protoliths of the young metamorphics may be equivalents of the Lasala Formation or were recycled from the Lasala Formation.     

Rock magnetics of carbonate systems–investigating palaeodune archives on Fuerteventura (Canary Islands)

The mineral magnetic properties of Pleistocene aeolian dune sands from the island of Fuerteventura (Canary Islands, Spain) were studied in order to reconstruct the palaeoenvironmental evolution of Pleistocene climates during their formation. The palaeodunes on Fuerteventura mainly consist of carbonate sands admixed with dust and material of volcanic origin. Due to the low magnetic background caused by the diamagnetic character of carbonate sands, these archives offer a lot of potential for environmental magnetic studies to detect the imprint of dust, volcanic material and paedogenesis. Four sections of alternating palaeosurface–aeolianite sequences in palaeodune fields have been analysed by means of extensive rock magnetic measurements. These Quaternary archives consist of deposits originating from different sources. I. material blown from the shallow shelf, II. material of volcanic origin, and III. long-range transported dust. The rock magnetic findings enable a more detailed interpretation of the palaeosurfaces within the sequences. We are able to differentiate semiquantitatively between the different source materials on one hand and to distinguish on the other hand those from soil-forming processes. Soil formation is only weakly developed in the dust imprints in the palaeosol aeolianite sequences, linked to sparse vegetation cover during the Pleistocene on Fuerteventura.     

Spatial rules that generate urban patterns: Emergence of the power law in the distribution of axial line length

This paper studies emergence/generation of power law in rank-order distribution of axial line length, which is a global pattern observed in real cities, due to interaction of a set of seven simple spatial rules at a local scale. These rules and their interactions form a model expected to simulate the morphological structure of free spaces in unplanned organic pedestrian small cities. Effects of each of the seven rules are discussed through repeated simulations of eight possible combinations of the rules, using a bottom-up process. The results show that the rules generate environments with statistically stable rank-order distribution of axial line length that follows the power law. It means that the axial maps of the simulated environments have a scale-free hierarchical structure such that their distributions lean toward short axial lines. It also represents dominance of local spatial structure, as the model renders a faster rate of growth at a local scale while allowing a steady growth at a global scale.     

The celestial mechanics approach: theoretical foundations

Gravity field determination using the measurements of Global Positioning receivers onboard low Earth orbiters and inter-satellite measurements in a constellation of satellites is a generalized orbit determination problem involving all satellites of the constellation. The celestial mechanics approach (CMA) is comprehensive in the sense that it encompasses many different methods currently in use, in particular so-called short-arc methods, reduced-dynamic methods, and pure dynamic methods. The method is very flexible because the actual solution type may be selected just prior to the combination of the satellite-, arc- and technique-specific normal equation systems. It is thus possible to generate ensembles of substantially different solutions—essentially at the cost of generating one particular solution. The article outlines the general aspects of orbit and gravity field determination. Then the focus is put on the particularities of the CMA, in particular on the way to use accelerometer data and the statistical information associated with it.     

Thermo‐mechanical interaction of a large impact melt sheet with adjacent target rock,Sudbury impact structure,Canada

The 1.85 Ga Sudbury Igneous Complex (SIC) and its thermal aureole are unique on Earth with regard to unraveling the effects of a large impact melt sheet on adjacent target rocks. Notably, the formation of Footwall Breccia, lining the basal SIC, remains controversial and has been attributed to impact, cratering, and postcratering processes. Based on detailed field mapping and microstructural analysis of thermal aureole rocks, we identified three distinct zones characterized by static recrystallization, incipient melting, and crystallization textures. The temperature gradient in the thermal aureole increases toward the SIC and culminates in a zone of partial melting, which correlates spatially with the Footwall Breccia. We therefore conclude that assimilation of target rock into initially superheated impact melt and simultaneous deformation after cratering strongly contributed to breccia formation. Estimated melt fractions of the Footwall Breccia amount to 80 vol% and attest to an extreme loss in mechanical strength and, thus, high mobility of the Breccia during assimilation. Transport of highly mobile Footwall Breccia material into the overlying Sublayer Norite of the SIC and vice versa can be attributed to Raleigh–Taylor instability of both units, long‐term crater modification caused by viscous relaxation of crust underlying the Sudbury impact structure, or both.