Complex patterns of schist tor exposure and surface uplift, Otago (New Zealand)

Landscapes are subjected to surface denudation during their complex and non-linear evolution. In order to quantify the in situ surface lowering and, thus, denudation or soil erosion rates, new, multi-millennia archives are needed and must be rigorously tested. Large residual rocks, tors, are the basis for the Tor Exhumation Approach. Here we present novel results on meta-sedimentary (schist) rock tors using this approach, which previously has only been applied in granitic terrains. The exhumation patterns of eight schist tors in three landscape locations (valley, ridge, distal) of Otago, New Zealand, were studied using cosmogenic dating. The in situ 10Be ages have high variability along individual vertical tor profiles. Average surface age is 122 ± 12 ka and ranges from 836 ± 89 ka to 19 ± 2 ka. The majority of investigated tors have surfaced during the MIS 5 which was one of the wettest and warmest climate periods. The resulting surface denudation trend of the three locations differs. The valley commenced denudation no earlier than ~200 ka with rates of ~0.22 [m kyr−1] to ~0.02 [m kyr−1]. In contrast, exposure started at the ridge position around 230 ka at ~0.03 [m kyr−1]. An age inversion found in the valley is considered to be the result of mushroom-like exposure by undercutting and repeated rock breakoffs. The distal site tor has been exhumed continuously for ~120 ka at a rate of ~0.2 to ~0.05 [m kyr−1]. We identified a mix of surface emergence patterns of the tors such as continuous-, mushroom-, tafoni- and structural-like. The comparison to modern erosion rates indicates that surface erosion has increased up to a factor of ten during the last few decades. To determine the actual surface uplift, we linked the tor derived surface denudation rates with rock uplift data. The data indicates that the surface uplift rates started to decrease during the Middle Pleistocene (0.04–0.09 [m kyr−1]), remained relatively low during the Late Pleistocene (~0.01 [m kyr−1]) and started to increase again during the Holocene (c. 0.21–0.64 [m kyr−1]). In summary, the emergence pattern of local tors enabled reconstruction of the evolution of Pleistocene-Holocene surfaces in East Otago

2-[2-(Benzyl­sulfan­yl)phen­yl]-1,1,3,3-tetra­methyl­guanidine

The mol­ecular structure of the title compound, C18H23N3S, shows it to be a derivative of an amino­thio­phenol possessing a tetra­methyl­guanidine group with a localized C=N double bond of 1.304 (2) Å and a protected thiol functional group as an S-benzyl thio­ether. The two aromatic ring planes make a dihedral angle of 67.69 (6)°

Soil weathering dynamics and erosion in a dry oceanic area of the southern hemisphere (Otago, New Zealand)

Landscape evolution is driven by tectonics, climate and surface denudation. In New Zealand, tectonics and steep climatic gradients cause a dynamic landscape with intense chemical weathering, rapid soil formation, and high soil losses. In this study, soil, and elemental redistribution along two adjacent hillslopes in East Otago, New Zealand, having different landscape settings (ridge versus valley) are compared to identify soil weathering and erosion dynamics. Fallout radionuclides ($^{239+240}$Pu) show that over the last ~ 60 years, average soil erosion rates in the valley (~ 260 [t km$^{−2}$ year$^{−1}$]) are low compared to the ridge (~ 990 [t km$^{−2}$ year$^{−1}$]). The ridge yields up to 26% lower soil weathering intensity than the topographical-protected valley. The lowest soil weathering intensity is found at both hilltop positions, where tors (residual rocks) are present and partially disintegrate. The soil weathering intensity increases with distance from tors, suggesting that tors rejuvenate the chemical weathering signature at the hilltop positions with fresh material. The inversed and decreasing weathering degree with all soil depth indicates that the fresh mineral contribution must be higher at the soil surface than at the bedrock weathering front. Higher erosion rates at the exposed ridge may be partially attributed to wind, consistent with rock abrasion of tors, and low local river sediment yields (56 [t km$^{−2}$ year$^{−1}$]). Thus, the East Otago spatial patterns of soil chemistry and erosion are governed by tor degradation and topographic exposure

Contrasting soil dynamics in a formerly glaciated and non-glaciated Mediterranean mountain plateau (Serra da Estrela, Portugal)

Few data are available on how soil erosion rates compare between surfaces of different ages because short-term processes often overprint the longer-term erosion signal. This study investigated the soil dynamics among two end-member sites, a formerly glaciated ('young', maximum glacial extent at 22-30 ka BP) and a non-glaciated ('old') area at the Serra da Estrela (Portugal). To disentangle soil distribution rates over different timeframes, isotopes for long-term (10Be), mid-term (delta C-13) and short-term (239+240Pu) periods were applied together with principles of the percolation theory.& nbsp;The formerly glaciated area has soils with a lower degree of weathering and lower carbon content compared to soils of the 'old', non-glaciated area. The selected isotopes and their distribution along the soil profiles revealed temporal differences in soil mixing process. It is hypothesised that the slightly higher elevation and formerly glaciated sites experienced cryoturbation effects over a longer period, while being less active or absent for the last few decades at the older, non-glaciated soils.& nbsp;The average long-term (millennia) soil erosion rates correspond to the expected higher rates at the younger surface and lower rates at the older surface. Once the formerly glaciated area became ice-free, soil erosion rates were high and decreased giving rise to average long-term rates of 101-140 [t km(-2) yr(-1)] for the older surfaces and 176-248 [t km(-2) yr(-1)] for the younger surfaces. In addition, seasonal freeze-thaw of the soils has persisted over a long period and affected the younger soils more intensively than the older soils. The current (last decades) soil redistribution rates, however, are up to one order of magnitude higher than the millennia rates and are controlled by surface angle and vegetation cover and less by soil texture. The more undulated, non-glaciated older surface had the highest short-term (decades) soil erosion rates in the range of 900-1700 [t km(-2 & nbsp;)yr(-1)], exhibits degrading conditions and relatively shallow soils. The younger soils, however, showed short-term (last few decades) average soil deposition rates of ~ 230 [t km(-2) yr(-1)]. Human impact (bush fires, grazing) is the cause for the currently strong soil degradation at the non-glaciated area.info:eu-repo/semantics/publishedVersio

Outline of Synthesis of Cognitive and Socio-cultural Foundations of Scientific Knowledge Evolution in Research Programs of Western Philosophy of Science

The article analyses the development of cognitive sociology of science, in the object field of which connection of cognitive and social structures of science is traced. The role of context in scientific knowledge formation is defined. It is stated that the basis for development of research program of cognitive sociology of science appeared to be reconsideration of the standard concept of science as a complex of gnoseological, epistemological and methodological interpretations of nature and morphology of the produced scientific knowledge, methods for its explanation and scientificity ideals. The difference between "strong" and «weak» varieties of scientific knowledge evolution, developed in western philosophy of science, is considered. "Social studies of science" are reviewed as a form of social constructivism and relativism, exhibiting their specific nature in macro-analytical and micro- analytical strategies of scientific knowledge evolution analysis. The thesis that multidimensionality of science cannot be adequately interpreted focusing only on conceptual history of science is proved

Prediction of Soil Formation as a Function of Age Using the Percolation Theory Approach

Recent modeling and comparison with field results showed that soil formation by chemical weathering, either from bedrock or unconsolidated material, is limited largely by solute transport. Chemical weathering rates are proportional to solute velocities. Nonreactive solute transport described by non-Gaussian transport theory appears compatible with soil formation rates. This change in understanding opens new possibilities for predicting soil production and depth across orders of magnitude of time scales. Percolation theory for modeling the evolution of soil depth and production was applied to new and published data for alpine and Mediterranean soils. The first goal was to check whether the empirical data conform to the theory. Secondly we analyzed discrepancies between theory and observation to find out if the theory is incomplete, if modifications of existing experimental procedures are needed and what parameters might be estimated improperly. Not all input parameters required for current theoretical formulations (particle size, erosion, and infiltration rates) are collected routinely in the field; thus, theory must address how to find these quantities from existing climate and soil data repositories, which implicitly introduces some uncertainties. Existing results for soil texture, typically reported at relevant field sites, had to be transformed to results for a median particle size, d50, a specific theoretical input parameter. The modeling tracked reasonably well the evolution of the alpine and Mediterranean soils. For the Alpine sites we found, however, that we consistently overestimated soil depths by ~45%. Particularly during early soil formation, chemical weathering is more severely limited by reaction kinetics than by solute transport. The kinetic limitation of mineral weathering can affect the system until 1 kyr to a maximum of 10 kyr of soil evolution. Thereafter, solute transport seems dominant. The trend and scatter of soil depth evolution is well captured, particularly for Mediterranean soils. We assume that some neglected processes, such as bioturbation, tree throw, and land use change contributed to local reorganization of the soil and thus to some differences to the model. Nonetheless, the model is able to generate soil depth and confirms decreasing production rates with age. A steady state for soils is not reached before about 100 kyr to 1 My

MONOPOL - A traveling-wave magnetic neutron spin resonator for tailoring polarized neutron beams

We report on first experimental tests of a neutron magnetic spin resonator at a very cold neutron beam port of the high flux reactor at the ILL Grenoble. When placed between two supermirror neutron polarizers and operated in a pulsed traveling-wave mode it allows to decouple its time- and wavelength-resolution and can therefore be used simultaneously as electronically tunable monochromator and fast beam chopper. As a first ‘real’ scientific application we intend its implementation in the PERC (p roton and e lectron r adiation c hannel) project related to high-precision experiments in neutron beta decay

Denudation variability of the Sila Massif upland (Italy) from decades to millennia using 10Be and 239+240Pu

Landscapes and soils evolve in non‐linear ways over millennia. Current knowledge is incomplete as only average denudation (or erosion) rates are normally estimated, neglecting the temporal discontinuities of these processes. The determination of regressive and progressive phases of soil evolution is important to our understanding of how soils and landscapes respond to environmental changes. The Sila Massif (Italy) provides a well‐defined geomorphological and geological setting to unravel temporal variations in soil redistribution rates. We used a combination of in situ cosmogenic radionuclide measurements (10Be) along tor (residual rock) height profiles, coupled with fallout radionuclides (239+240Pu) in soils, to model soil denudation rates over the last 100 ka. We measured rates prior to the Last Glacial Maximum (LGM) of ≤30 t km−2 yr−1 (~0.036 mm yr−1). Following the LGM, during the transition from the Pleistocene to the Holocene, these rates increased to ~150–200 t km−2 yr−1 and appeared to be above soil production rates, causing regressive soil evolution. For the last ~50 years, we even describe erosion rates of ≥1,000 t km−2 yr−1 (~1.23 mm yr−1) and consider human impact as the decisive factor for this development. Consequently, the natural soil production rates cannot cope with the current erosion rates. Thus, a distinct regressive phase of soil formation exists, which will give rise to shallowing of soils over time. Overall, our multimethod approach traced denudation and erosion histories over geologic and human timescales and made a new archive to soil science and geomorphology accessible

Two Multiâ Center Studies Evaluating Locally Delivered Doxycycline Hyclate, Placebo Control, Oral Hygiene, and Scaling and Root Planing in the Treatment of Periodontitis

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142011/1/jper0490.pd