Effect of block rotation on the pitch of slickenlines

Rotation of faults or pre-existing weakness planes produce two effects on the slickenlines of fault planes. First, the rotation leads to changes in the pitch of slickenlines. As a result, the aspect of the pre-existing fault may change. For example, after rotation, a normal fault may show features of an oblique fault, a strike-slip fault, or a thrust fault. Second, due to rotation, stress states on the fault planes are different from those before the rotation. As a consequence some previous planes may be reactivated. For an isolated plane, the reactivation due to rotation can produce new sets of slickenlines. With block rotation, superimposed slickenlines can be generated in the same tectonic phase. Thus, it is not appropriate to use fault-slip data from slickenlines to analyze the stress tensor in a region where there is evidence of block rotation. As an example, we present the data of slickenlines from core samples in the Tunich area of the Gulf of Mexico. The results wrongly indicate that the calculated stress tensor deviates from the far-field stress tensor.     

Happiness is greater in natural environments

Links between wellbeing and environmental factors are of growing interest in psychology, health, conservation, economics, and more widely. There is limited evidence that green or natural environments are positive for physical and mental health and wellbeing. We present a new and unique primary research study exploring the relationship between momentary subjective wellbeing (SWB) and individuals’ immediate environment within the UK. We developed and applied an innovative data collection tool: a smartphone app that signals participants at random moments, presenting a brief questionnaire while using satellite positioning (GPS) to determine geographical coordinates. We used this to collect over one million responses from more than 20,000 participants. Associating GPS response locations with objective spatial data, we estimate a model relating land cover to SWB using only the within-individual variation, while controlling for weather, daylight, activity, companionship, location type, time, day, and any response trend. On average, study participants are significantly and substantially happier outdoors in all green or natural habitat types than they are in urban environments. These findings are robust to a number of alternative models and model specifications. This study provides a new line of evidence on links between nature and wellbeing, strengthening existing evidence of a positive relationship between SWB and exposure to green or natural environments in daily life. Our results have informed the UK National Ecosystem Assessment (NEA), and the novel geo-located experience sampling methodology we describe has great potential to provide new insights in a range of areas of interest to policymakers.     

Holocene sea-surface temperature variability in the Chilean fjord region

Here we provide three new Holocene (11–0 cal ka BP) alkenone-derived sea surface temperature (SST) records from the southernmost Chilean fjord region (50–53°S). SST estimates may be biased towards summer temperature in this region, as revealed by a large set of surface sediments. The Holocene records show consistently warmer than present-day SSTs except for the past ~ 0.6 cal ka BP. However, they do not exhibit an early Holocene temperature optimum as registered further north off Chile and in Antarctica. This may have resulted from a combination of factors including decreased inflow of warmer open marine waters due to lower sea-level stands, enhanced advection of colder and fresher inner fjord waters, and stronger westerly winds. During the mid-Holocene, pronounced short-term variations of up to 2.5°C and a cooling centered at ~ 5 cal ka BP, which coincides with the first Neoglacial glacier advance in the Southern Andes, are recorded. The latest Holocene is characterized by two pronounced cold events centered at ~ 0.6 and 0.25 cal ka BP, i.e., during the Little Ice Age. These cold events have lower amplitudes in the offshore records, suggesting an amplification of the SST signal in the inner fjords.     

Explicit meshfree solution for large deformation dynamic problems in saturated porous media

In this paper a new methodology to simulate saturated soils subjected to dynamic loadings under large deformation regime (locally up to 40% in equivalent plastic strain) is presented. The coupling between solid and fluid phases is solved through the complete formulation of the Biot’s equations. The additional novelty lies in the employment of an explicit time integration scheme of the \(u-w\) (solid displacement–relative fluid displacement) formulation which enables us to take advantage of such explicit schemes. Shape functions based on the principle of maximum entropy implemented in the framework of Optimal Transportation Meshfree schemes are utilized to solve both elastic and plastic problems.     

Raman spectroscopic and scanning electron microscopic analysis of a novel biological colonisation of volcanic rocks

A novel type of colonisation of a basaltic rock, collected on the Arctic island of Svalbard, Norway, during the AMASE expedition in 2004, was characterised using Raman spectroscopy and Scanning Electron Microscopy (SEM). The sample contains two different types of extremophile communities, one occurring behind a radial white crystallisation and the other occurring inside a dark vacuole. Several types of minerals and microbial colonies have been identified by both Raman spectroscopy and SEM analyses. It is the first time that photosynthetic communities have been documented to colonise the inside of dark basaltic rocks. Our discovery has important implications for planetary exploration because it extends the analytical capability and our understanding of microbial rock colonisations to subaerial volcanic outcrops and has wide implications towards the search for life in extraterrestrial planets. In this work we also demonstrate that the use of different laser wavelengths for Raman spectroscopic studies and complementary microscopic analysis are critical for a comprehensive organic and inorganic compound identification.     

Constraining Theoretical Models with Astronomical and Geophysical Bounds

We consider astronomical and geophysical bounds in order to test Kaluza-Klein like models and some particular models of Bekenstein's theory. Bounds on the free parameteres of the theories are obtained. This revised version was published online in July 2006 with corrections to the Cover Date.     

Constraints regarding gold deposition in episyenites: the Permian episyenites associated with the Villalcampo Shear Zone, central western Spain

The Villalcampo Shear Zone (around 307 Ma) shows second-order shear zones (420–390 °C) with gold ore bodies hosted by episyenites, which consist of albite episyenites (albitites) and albite-Kfs episyenites, both types with different contents in sulphides and gold. Mass transfer modelling supports higher fluid/rock ratios in albitites than in albite-Kfs episyenites. The study of worldwide barren and gold-bearing episyenites reveals abundant sulphides in the latter as a distinguishing feature. The electrochemical processes at the surface of sulphide would have enhanced gold precipitation, sulphides working as a gold trap. A complex fluid history occurred in gold ore bodies hosted by episyenites, although in essence, it was similar to quartz-sealed faults hosting late Variscan gold deposits: (a) an early fluid equilibrated with the metamorphic pile with sulphides or with a metamorphic fingerprint, resulted in a sulphide deposition and (b) a shallower fluid reservoir of meteoric origin provided gold deposition. In contrast to earlier claims regarding episyenite fluid flow, a down temperature and probably an upwards fluid flow are proposed for the episyenitization process, also in keeping with the early stages of fluid flow in quartz-sealed faults. Fluid inclusions in albite confirm that the striking coupled quartz leaching albitization processes occurred around 400 °C and 60 MPa, crosscutting the retrograde solubility field of silica and yielding a vuggy rock. Initially, albite, and later quartz and sulphide, filled the vugs from the same or a very similar fluid. Uraninites deposited during the albitization and probably the onset of the sulphide deposition afforded the same age (270 ± 12 Ma) as other Spanish episyenites, confirming a synchronous and a regional-scale process and ruling out a relationship with the granite cooling history (324 ± 11 Ma).     

Reactive Transport Modeling of Subaqueous Sediment Caps and Implications for the Long-Term Fate of Arsenic, Mercury, and Methylmercury

A 1-D biogeochemical reactive transport model with a full set of equilibrium and kinetic biogeochemical reactions was developed to simulate the fate and transport of arsenic and mercury in subaqueous sediment caps. Model simulations (50?years) were performed for freshwater and estuarine scenarios with an anaerobic porewater and either a diffusion-only or a diffusion plus 0.1-m/year upward advective flux through the cap. A biological habitat layer in the top 0.15?m of the cap was simulated with the addition of organic carbon. For arsenic, the generation of sulfate-reducing conditions limits the formation of iron oxide phases available for adsorption. As a result, subaqueous sediment caps may be relatively ineffective for mitigating contaminant arsenic migration when influent concentrations are high and sorption capacity is insufficient. For mercury, sulfate reduction promotes the precipitation of metacinnabar (HgS) below the habitat layer, and associated fluxes across the sediment–water interface are low. As such, cap thickness is a key design parameter that can be adjusted to control the depth below the sediment–water interface at which mercury sulfide precipitates. The highest dissolved methylmercury concentrations occur in the habitat layer in estuarine environments under conditions of advecting porewater, but the highest sediment concentrations are predicted to occur in freshwater environments due to sorption on sediment organic matter. Site-specific reactive transport simulations are a powerful tool for identifying the major controls on sediment- and porewater-contaminant arsenic and mercury concentrations that result from coupling between physical conditions and biologically mediated chemical reactions.     

Feeding ecology of flatfish juveniles (pleuronectiformes) in Mar Chiquita coastal lagoon (Buenos Aires, Argentina)

During a two-year period in Mar Chiquita coastal lagoon (Buenos Aires, Argentina), the diet of juvenileParalichthys orbignyanus andOncopterus darwinii sorted according to size, area, and season was analyzed. Sampling was carried out using a beach seine net in three zones of different salinity. The small size of the individuals collected and the high percentage of full stomachs, corresponding with high food availability in the lagoon, indicated that Mar Chiquita is used as a nursery ground. The diet ofP. orbignyanus consisted of crustaceans and polychaetes, whereasO. darwinii fed predominantly on small crustaceans (gammarid amphipods, harpacticoid copepods, mysids, and ostracods); polychaetes were less important. Diet of both flatfish species varied with length. Smaller individuals were microphagous, while bigger specimens included larger prey in their diet. Prey taxa number increased for both species, seawards to the mouth of the lagoon, probably related to the salinity gradient. Prey diversity forP. orbignyanus was highest in autumn and spring, and the lowest percentage of stomachs with food occurred in winter. Prey diversity was lowest forO. darwinii in spring and the highest percentage of empty stomachs was found in autumn.