Miracle-dz/UniFAR-FTUs huggingface dataset:
Crustal thinning between the Ethiopian and East African plateaus from modeling Rayleigh wave dispersion

A 500‐km wide region separating the East African and Ethiopian plateaus is one of the few places within the African Superswell with elevations below 1 km. The region encompasses much of southeastern Sudan and northern Kenya and experienced both Mesozoic and Cenozoic rifting. Crustal and uppermost mantle structure is investigated in the region by modeling Rayleigh wave dispersion measurements. Modeling results give Sn velocities of 4.1–4.3 km/s and average crustal thickness of 25 ± 5 km, some 10–15 km thinner than the crust beneath the East African and Ethiopian Plateaus. The isostatic response from 10 to 15 km of crustal thinning is sufficient to account for the low elevations between the plateaus.
Trophodynamic analysis of polychlorinated biphenyl congeners and other chlorinated hydrocarbons in the Lake Ontario ecosystem

The bioaccumulation of polychlorinated biphenyl (PCB) congeners and some other chlorinated organics in the Lake Ontario ecosystem has been studied. In addition to the classical biomagnification of PCBs and some of the other organics, the chlorine content of the PCBs was observed to increase with trophic level. Most of the differential PCB fractionation seemed to occur at the lower end of the food chain (water to plankton to mysid). At the higher trophic levels (mysid to smelt to salmonid), the PCBs seemed to be distributed as a uniform composition mixture. The bioaccumulation factor of these hydrophobic organics increased linearly with octanol-water partition coefficient of the chemicals at all trophic levels. The environmental bioaccumulation of these chemicals in salmonids was higher than that predicted from bioconcentration from water alone, showing that contaminated food is a major source of these chemical residues in fish.
Danopolonian migmatization of Mesoproterozoic sedimentary rocks in southernmost Sweden: a SIMS zircon study

To assess the age and origin of the metasedimentary migmatites in southernmost Sweden and their relationships with the Mesoproterozoic granitoid magmatism in the area, we have dated migmatite zircon using the secondary ion mass spectrometry U–Pb method. The studied metasedimentary migmatites, here called the Nöteboda migmatites, occur along the southwestern boundary of the 1442 Ma Tåghusa granitoid intrusion in southeastern Skåne. They contain the mineral assemblage garnet+biotite ± muscovite+cordierite+sillimanite+quartz+plagioclase+K-feldspar and were formed during a retrograde evolution from c. 750–720°C and 6 kbar (peak conditions) to c. 675°C and 4 kbar. Zircon is characterized by detrital cores surrounded by U-rich rims and overgrowths. Separate rounded metamorphic grains also exist. The age probability–density distribution peaks for detrital zircon are at c. 1700, 1670, 1650, 1610, 1570 and 1530 Ma. These ages suggest Gothian orogenic rocks in the present west as the most probable principal source. Sedimentation occurred after c. 1530 Ma, the age of the youngest detrital zircon, indicating the existence of a previously unknown period of Mesoproterozoic sedimentation in southernmost Sweden. A homogeneous zircon overgrowth yielded a concordant 207Pb/206Pb age of 1439 ± 5 Ma, which dates the migmatization and is close to the age of the Tåghusa intrusion. We conclude that the burial of the sediments down to c. 20 km, their metamorphism and progressive migmatization took place concurrently with granitic magmatism, NE–SW compression, folding and shearing of the crust between 1460 and 1440 Ma during the Danopolonian orogeny.
Short paper: The significance of mid-Palaeozoic basement in Graham Land, Antarctic Peninsula

A mid-Palaeozoic basement to the Antarctic Peninsula is confirmed by a geochronological study of the gneissose country rock of the Mesozoic magmatic arc of eastern Graham Land. Rb–Sr whole-rock ages of 410 ± 15 and 426 ± 12 Ma from samples of orthogneiss indicate a previously unrecognized episode of granitic magmatism in the Antarctic Peninsula during the Silurian. Sm–Nd data on garnet–whole-rock pairs indicate that subsequent amphibolite facies metamorphism occurred in late Carboniferous times, probably as a result of plutonism.
Magnetisation mapping in rugged terrain

Magnetisation mapping aims to derive a map of the surface magnetisation (or equivalently, apparent susceptibility) distribution to assist in geological mapping through a more precise delineation of magnetisation boundaries and by providing a map of magnetisation levels that can be directly related to rock properties. The mapping surface can be either the magnetic basement, which generally corresponds to the crystalline basement, or, where non-magnetic overburden thickness is small, the ground topography. When the mapping surface and the survey altitude are both constant, magnetisation mapping reduces to a downward continuation of the observed magnetic field. Draped-survey flying in rugged terrain presents problems for magnetisation mapping due to variable sensor altitude and changing ground topography. Changes in the depth to the magnetic sources lead to variable attenuation of the magnetic anomalies. If the dominant wavelengths of the ground topography are comparable to changes in magnetisation, then topographically-induced anomalies will be indistinguishable from the effects of magnetisation changes. Therefore, the standard magnetisation mapping approach is modified in order to address these problems: 1) the varying sensor height is dealt with by using an approximate equivalent geometry from which the magnetic data can be more easily inverted; 2) the change in ground elevation is overcome by using an iterative inversion procedure that takes into account the varying source-to-observation distance; 3) finally, a correction is applied that accounts for errors introduced by the transformation of geometries. This approach is demonstrated on a recent aeromagnetic survey of the Tatla Lake region, British Columbia, Canada.
Crystallographic Controls on the Alteration of Microcline Perthites from the Spruce Pine District, North Carolina

Altered perthites from a weathered pegmatite in the Spruce Pine District, North Carolina, were characterized by electron microprobe as a K-rich microcline host with lesser Na-rich plagioclase having a lamellar morphology. Light-optical and transmission electron microscopy (TEM) show microtextural elements such as phase boundaries, holes and microfractures that could serve as potential nucleation sites for alteration to clay minerals.The host microcline contains albite and pericline twinning textures that vary in character; the amount of each twinning type and/or the size of twin individuals changes on a u.m scale. Plagioclase ranges from large lamellar vein and film albite (visible in the light microscope) to cryptoperthite whose size ranges from u.m to perhaps 100 Å. The smallest-scale albite appears to be a late-stage phase of exsolution in which lamellae have nucleated heterogeneously on albite-twin composition planes in the microcline.Alteration is concentrated in vein and film albite, especially along grain boundaries with microcline. Powder X-ray diffraction (XRD) patterns of intensely altered pegmatite show halloysite. Holes, microfractures, vein albite/host microcline boundaries and microcline/halloysite boundaries trend parallel to the traces of (010) and {110}, suggesting that these directions are pathways along which fluids migrate. Cleavage and microfractures occur along, and holes are bounded by, these directions. Holes are associated with dislocations and the latter are observed at feldspar/clay boundaries. Twin domains and cryptoperthitic albite are less susceptible to alteration than coarse lamellar albite and regions containing negative crystals and microfractures. However, microtextures in some areas containing halloysite suggest that once fluids penetrate the crystal, alteration may proceed preferentially in more strongly twinned regions.
FISH HABITAT OPTIMIZATION TO PRIORITIZE RIVER RESTORATION DECISIONS

This paper examines and ranks restoration alternatives for improving fish habitat by evaluating tradeoffs between fish production and restoration costs. Optimization modelling is used to maximize out‐migrating coho salmon (Oncorhynchus kisutch) from a natal stream and is applied as a case study in California's Shasta River. Restoration activities that alter flow and water temperature conditions are the decision variables in the model and include relocating a major diversion, increasing riparian shading, increasing instream flow, restoring a cool‐water spring and removing a dam. A budget constraint limits total restoration expenditures. This approach combines simple fish population modelling with flow and water quality modelling to explore management strategies and aid decision making. Previous fish habitat optimization research typically uses single restoration strategies, usually by altering reservoir releases or modifying outlet structures. Our method enlarges the solution space to more accurately represent extensive and integrated solutions to fish habitat problems. Results indicate that restoration alternatives can be prioritized by fish habitat improvement and restoration cost. For the Shasta River case study, considerable habitat restoration investments were required before fish productivity increased substantially. This exercise illustrates the potential of ecological optimization for highlighting promising restoration approaches and dismissing poor alternatives. Copyright © 2011 John Wiley & Sons, Ltd.
Compacting and dilating shear bands in porous rock: Theoretical and experimental conditions

The failure of rocks in the brittle regime is generally associated with the appearance of strain localization bands. For very porous rocks, three types of strain localization can be distinguished: extension bands, shear bands, and compaction bands. The first is associated with an extensional normal strain concentration inside the band; the second, with a shear strain concentration; and the third, with a compressive normal strain concentration. This paper shows the continuous transition between pure extension bands and pure compaction bands, via shear bands that evolve from dilating shear bands to compacting shear bands. By an extension to the analysis of Rudnicki and Rice [1975] (RR) on strain localization in pressure sensitive rocks, the prediction of the strain type inside bands at the onset of localization shows that inside shear bands, the shear strain can be associated with a volumetric dilatancy or compaction depending on the constitutive parameters of the material. The theoretical determination of the strain type is in accordance with recent observations of dilating and compacting shear bands in laboratory tests on porous sandstone specimens. A limit for the existence of a localized reduction of porosity within the band is expressed. A physical limit to the RR model is also proposed to insure continuity of the strain mechanism of localization with respect to the constitutive parameters.
If Mapping Contaminated Sediment in Hamilton Harbour, Ontario

Hamilton Harbour lies at the western end of Lake Ontario, and has a long history of industrial activity and urban development. Elevated levels of metals and organic compounds in bottom sediments led the International Joint Commission to designate Hamilton Harbour as an Area of Concern. Development of a remediation strategy requires definition of the distribution of the contaminants. Direct measurement of contamination by chemical analysis is prohibitively expensive. Previous studies on subsampled cores have shown that magnetic susceptibility closely tracks contaminant levels. This paper show show non-destructive measurements of magnetic susceptibility (K) on unopened cores can be used to map the distribution of post-industrial contaminated sediments and determine areas of recent sediment disturbance. Resume Le Port de Hamilton que est situe a l'extremite ouest du lac Ontario, a connu une longue suite d'activites industrielles et de developpements urbains. L'existence de niveaux eleves de metaux et de composes organiques dans les sediments du fond du lac a amene la Comission conjointe internationale a accorder le statut de Secteur preoccupant au Port de Hamilton. L'elaboration d'une strategie de restauration exige d'abord que l'on connaisse la distribution des polluants. L'evaluation de degre de contamination par des analyses chimiquessur echantillons s'avere beaucoup trop dispendieuse. Des etudes effectuees sur des sous-echantillons ont montre que les mesures de la susceptibilite magnetique suivent de pres les niveaux de contamination. Le present article montre comment une methode de mesure de la susceptibilite magnetique (K) sur des carottes d'echantillonnage vierges peut etre utilisee pour cartographier la distribution des sediments contamines post-industriels, permettant ainsi de localiser les endroits de remaniement recents.
Coherent region-, species-, and frequency-dependent local climate signals in northern hemisphere tree-ring widths

AbstractPatterns of correlation between tree rings and local temperature or precipitation are investigated using 762 International Tree-Ring Data Bank standardized ring width site chronology time series, and a gridded dataset of temperature and precipitation. Coherent regional- and, in some cases, hemispheric-scale patterns of correlation are found in the extratropical Northern Hemisphere for both the summer prior to and the summer concurrent with ring width formation across different species and over large distances.Among those chronologies that are primarily linked to temperature, thicker ring widths are generally associated with anomalously cool prior summer temperature and anomalously warm concurrent summer temperature. Reconstructions of local summer temperature using prior, concurrent, and/or subsequent year ring widths as predictors demonstrate that useful climate–growth information generally exists in ring widths that are both concurrent with and subsequent to the summer temperature anomaly. Consi.
Evolution of retreating subduction boundaries formed during continental collision

Retreating subduction boundaries, formed where the rate of subduction exceeds the rate of overall plate convergence, appear to be commonly developed features within regions of early or incomplete continent-continent collision. They are characterized by regional extension within the overriding plate and, at their leading edge, by thin-skinned arcuate thrust belts that are concave towards the overriding plate. As is illustrated by examples from the Mediterranean region, the formation of retreating subduction boundaries is intimately related to the process of continental collision. During the early stages of collision, retreating subduction boundaries are commonly formed by lateral ejection from zones of crustal shortening along the main collision boundary. Retreating plate boundaries can also form before the main collision, and the associated thrust belts emplaced as precollisional accretionary assemblages. Because the driving mechanism for retreating subduction boundaries appears to be gravity acting on a dense subducted slab (slab pull), subduction usually ceases when, and only when, thick buoyant continental crust enters the subduction zone. Thus differences in the evolution and duration of retreating subduction systems can be largely attributed to the size and configuration of the deep water regions available to be subducted. In some cases, retreating subduction boundaries may “escape” into the open ocean, where they form nearly isolated, local tectonic systems. In these systems the rate of subduction is approximately compensated by the rate of upper plate extension, and migration of the system across the oceanic region may be very rapid. For example, the Horseshoe Seamounts, located about 800 km offshore in the eastern North Atlantic, may be the active expression of an east dipping, westwardly migrating retreating subduction boundary that has evolved from the Betic Cordillera-Rif system active in Miocene time and may now be progressing across the Atlantic at approximately 50 mm/yr. An analogous situation may be represented by the Scotia Arc system, a westward dipping retreating subduction system located between the South American and Antarctic plates, which may have “escaped” into the South Atlantic ocean from a zone of crustal shortening in the Andes and is now progressing across the Atlantic at a rate of about 80 mm/yr.
Monitoring what matters : tailoring millennium targets and indicators of environmental sustainability to local conditions in ECA

The Millennium Development Goals (MDGs), with associated targets and indicators, have become widely accepted as a framework for measuring broad progress in reducing poverty and improving living standards worldwide. MDG related to environmental sustainability- reflects human aspiration worldwide to reverse the loss of critical environmental resources, improve sustainable access to safe water and adequate sanitation, and pull people out of slums. The objective of this study was to build on these efforts and facilitate a country-driven process of identifying or developing complementary indicators for MDG that are more relevant for the people in the Europe and Central Asia (ECA) region. The paper focuses on three countries: Albania, Tajikistan, and Georgia. It also presents more limited information collected from five additional countries that were the subject of the 2004 study: Armenia, Kazakhstan, the Kyrgyz Republic, Moldova, and Serbia and Montenegro. The 2004 analyses focused on collecting and analyzing data on the 'official' global framework indicators within the United Nations (UN) framework such as the joint monitoring program, which collects global framework indicators of access to water supply and sanitation. This paper shows that a country-driven process of developing complementary indicators of environmental sustainability can add important value to the standard framework for measuring progress in achieving the MDG. The study demonstrated how these efforts can be structured and facilitated through a country-driven process. It also demonstrates that these efforts are challenging to the countries in the region and that they require targeted support from the international community to be successful.
Horizontal redistribution with capillary hysteresis

Exact and relatively simple analysis is possible for one hysteretic redistribution process, that in long horizontal columns with the two parts, x 0, at different uniform moisture contents θ1 and θ2 (θ1 > θ2) at time t = 0. We formulate and solve this problem. The key to its simplicity is its similarity character, with moisture profile x(θ) proportional to t1/2. At the interface x = 0 there is, for t > 0, a permanent and constant moisture content jump θ3 to θ4 (θ3 > θ4). The operative moisture potential is the primary drying potential for x 0, θ4 ≥ θ ≥ θ2. The operative moisture diffusivity is the primary drying diffusivity for x 0. The drying diffusivity is greater than the wetting diffusivity near θ = θ1 and less near θ = θ2 Solutions are found for illustrative examples corresponding to four values of H, the relative magnitude of the hysteresis loop. The resorptivity R, the total wet-to-dry exchange of water across x = 0 in reduced form, is analogous to the sorptivity S in absorption and infiltration. For the calculated examples, R is about one third of S for the corresponding absorption process and varies only mildly with H. Nonhysteretic calculations may thus give reasonable estimates of R for horizontal hysteretic redistribution, though they cannot give details such as the moisture jump at x = 0, Desorption moisture profiles for x 0 are relatively steep, and the penetration depth small. It follows that in experiments the initially wet section of the column should be made some 5–10 times longer than the initially dry sector.
Identifying multiple time scale rainfall controls on Mojave Desert ecohydrology using an integrated data and modeling approach for Larrea tridentata

The perennial shrub Larrea tridentata is widely successful in North American warm deserts but is also susceptible to climatic perturbations. Understanding its response to rainfall variability requires consideration of multiple time scales. We examine intra‐annual to multiyear relationships using model simulations of soil moisture and vegetation growth over 50 years in the Mojave National Preserve in southeastern California (USA). Ecohydrological model parameters are conditioned on field and remote sensing data using an ensemble Kalman filter. Although no specific periodicities were detected in the rainfall record, simulated leaf‐area‐index exhibits multiyear dynamics that are driven by multiyear (∼3 years) rains, but with up to a 1 year delay in peak response. Within a multiyear period, Larrea tridentata is more sensitive to winter rains than summer. In the most active part of the root zone (above ∼80 cm), >1 year average soil moisture drives vegetation growth, but monthly average soil moisture is controlled by root uptake. Moisture inputs reach the lower part of the root zone (below ∼80 cm) infrequently, but once there they can persist over a year to help sustain plant growth. Parameter estimates highlight efficient plant physiological properties facilitating persistent growth and high soil hydraulic conductivity allowing deep soil moisture stores. We show that soil moisture as an ecological indicator is complicated by bidirectional interactions with vegetation that depend on time scale and depth. Under changing climate, Larrea tridentata will likely be relatively resilient to shorter‐term moisture variability but will exhibit higher sensitivity to shifts in seasonal to multiyear moisture inputs.
Victims of Benevolence: The Dark Legacy of the Williams Lake Residential School by Elizabeth Furniss/ The Oblate Assault on Canada's Northwest by John Scofield

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Enhanced Open Ocean Storage of CO2 from Shelf Sea Pumping

Seasonal field observations show that the North Sea, a Northern European shelf sea, is highly efficient in pumping carbon dioxide from the atmosphere to the North Atlantic Ocean. The bottom topography–controlled stratification separates production and respiration processes in the North Sea, causing a carbon dioxide increase in the subsurface layer that is ultimately exported to the North Atlantic Ocean. Globally extrapolated, the net uptake of carbon dioxide by coastal and marginal seas is about 20% of the world ocean's uptake of anthropogenic carbon dioxide, thus enhancing substantially the open ocean carbon dioxide storage.
Lateral Migration Rates of River Bends

Time sequential aerial photographs flown approximately 20 to 30 years apart have been used to measure the lateral migration rates of 189 bends on 21 clay, sand and gravel rivers in western Canada. Channel migration rates transformed to a reference bend curvature (r/w = 2.5) are shown to be a simple function of stream power, outer-bank height, and a coefficient of resistance to lateral migration Υ\N\db. This coefficient in turn is shown to be a function of the texture of the outer bank materials, with a complex form similar to that of the Hjulstrom or Shields sediment entrainment function. The task of specifying the channel migration rate appears to be essentially a sediment transport problem.