Miracle-dz/UniFAR-FTUs huggingface dataset:
Geology, geochronology, and rift basin development in the central sector of the Main Ethiopia Rift

Based on stratigraphic relationships and K/Ar dating of volcanic rocks from both of the escarpments, flanking plateaus, and from the rift floor of the central sector of the Main Ethiopian Rift, six major volcanic episodes are recognized in the rift9s development over a time span from the late Oligocene to the Quaternary. Using the K/Ar data, correlation of volcanic units from the six periods of activity throughout the study area forms the basis for establishing six time-stratigraphic chronozones for the central sector that are related to volcanism in the Ethiopian Cenozoic volcanic province. The oldest basalt and rhyolite flows exposed along the rift margins of the central sector are time correlative to, or older than, those in river canyons (for example, Blue Nile) on the adjacent northwest plateau. A thinned Mesozoic stratigraphic sequence along the Guraghe western rift margin suggests that doming may have preceded volcanism and rifting of the Cenozoic. By late Miocene time, at least by 8.3 Ma and 9.7 Ma, the eastern and western faulted margins, respectively, of the rift had formed at Guraghe and at Agere Selam as indicated by containment of flows of that age within the rift wall during eruption. A paroxysm of calc-alkaline ignimbrite activity produced voluminous flows nearly fully contained within the rift during the Pliocene epoch. The Munesa Crystal Tuff (3.5 Ma), a prominent marker tuff exposed on both rift margins, is present at depth in a geothermal well beneath the rift floor and indicates a minimum of 2 km of downthrow in the central sector since its eruption. Structural and stratigraphic relationships in the central sector indicate a two- stage rift development. This is characterized by an early phase (late Oligocene or early Miocene) of a series of alternating opposed half-grabens along the rift with alternating polarity, such as that in the present Gregory and Western Rifts of East Africa and symmetrical rifts that evolved from these grabens in late Miocene or early Pliocene time. Thus, evolution from alternating half-graben to a full symmetrical graben with a medially located neovolcanic zone that is bifurcated to marginal grabens in the northern part of the study area may be a fundamental part of the rifting process. The study indicates that there are major petrologic and tectonic differences between the Main Ethiopian Rift and the Gregory (Kenyan) Rift.
Prediction of monthly‐seasonal precipitation using coupled SVD patterns between soil moisture and subsequent precipitation

It was suggested in a recent statistical correlation analysis that predictability of monthly‐seasonal precipitation could be improved by using coupled singular value decomposition (SVD) patterns between soil moisture and precipitation instead of their values at individual locations. This study provides predictive evidence for this suggestion by comparing skills of two statistical prediction models based on the coupled SVD patterns and local relationships. The data used for model development and validation are obtained from a simulation over East Asia with a regional climate model. The results show a much improved skill with the prediction model using the coupled SVD patterns. The seasonal prediction skill is higher than the monthly one. The most remarkable contribution of soil moisture to the prediction skill is found in warm seasons, opposite to that of sea surface temperature.
Choosing an AEM System to Look for Kimberlites - A Modelling Study

Will time domain or frequency domain AEM systems be more effective when looking for kimberlites? In this study, a 3D integral equation program was used to contrast the responses of a kimberlite pipe with a weathered clay cap in a resistive host environment for several types of AEM systems. Three towed bird time-domain systems were simulated, an idealised Geotem 25 Hz, and Geotem 75 Hz system (step and impulse responses) plus a Tempest 25 Hz pure step system. For the type of model studied, on-time B and sub-millisecond off-time dB/dt gave the best responses. The horizontal component response was much more informative than the vertical component. The response of a generic helicopter EM system with five frequencies, ranging from 500 Hz to 50000 Hz was also simulated. Both coplanar and coaxial configurations were used with transmitter-receiver offsets of 6 and 8 m. A horizontal dipole coplanar wingtip system was also modelled using the same frequencies. When measuring the horizontal component, the three systems gave exactly the same percent anomaly response. PPM (parts per million) responses were identical in shape but differed in magnitude by a factor of the separation distance cubed. The horizontal component had more shape information than did the vertical component. For the model studied, maximum discrimination above background occurred between 5000 to 10000 Hz for the quadrature component. The in-phase anomalous response increased monotonically with frequency. The kimberlite targets used in this study were defined to be poor conductors and therefore time-domain definition required accurate measurements either during on-times or at sub-ms offtimes. Thus helicopter-borne frequency-domain EM systems offered the best practical choice for this type of target. A model component analysis showed that although the weathered clay cap was the main part of the EM response, the unweathered kimberlite could be detected in the absence of the cap. The presence of a kimberlite pipe underneath the cap showed a broadened response compared with the response of the cap alone.
The importance of constraining regional exhumation in basin modelling: a hydrocarbon maturation history of the Ghadames Basin, North Africa

Estimation of eroded overburden at unconformities is essential to accurately constrain burial histories and predict the timing of hydrocarbon maturation. In the Ghadames Basin, three independent techniques, palaeo-isopach construction, sonic velocity and vitrinite reflectance analysis, were employed. The resultant basin model suggests that only the two most significant unconformities, the Hercynian (Late Carboniferous) and Alpine (early Eocene), have a major control on timing of hydrocarbon charge. Modelling indicates only one period of generation from the Lower Silurian shales on the western margin of the basin, with 95% hydrocarbon generation prior to Hercynian exhumation. The central basin and southern margin experienced maximum burial during Eocene time. The Middle–Upper Devonian mudstones are the main source rocks and they did not generate significant volumes of hydrocarbons over the basin centre until Cretaceous time; they are currently within the peak oil generation zone. In Libya, on the eastern/northeastern flank of the basin, results indicate Cenozoic maximum burial, followed by up to 2000 m of Alpine exhumation. The magnitude of this exhumation has not been recognized previously, although it is a critical component of the basin model as it has a major impact on potential hydrocarbon charge in this area. Maturation models predict that the Lower Silurian source underwent two generative phases: (1) pre-Hercynian (Carboniferous) generation; and, significantly, (2) post-Hercynian (Late Jurassic–Cenozoic) generation. The identification of late hydrocarbon generation offers potential for oil and gas to migrate into post-Hercynian traps. Over the western, northern and eastern flanks, the Devonian source rocks remain immature/ marginally mature at present day.
Late Quaternary glacial and deglacial history of eastern Vestfirdir, Iceland using cosmogenic isotope (36Cl) exposure ages and marine cores

The late glacial and deglacial history of Vestfirdir, NW Iceland is interpreted from terrestrial field‐based evidence and compared with marine cores and seismic studies. Understanding the timing of deglaciation is complicated by a lack of dateable organic material on land, uncertainties associated with interpretation of diamictons, and ambiguities in radiocarbon dating. New 36Cl exposure ages of boulders and bedrock surfaces suggest that at least part of the coastal uplands were ice‐free by approximately 20 ka. Deglaciation of the valleys followed. Boulders from the crest of an end‐moraine in the Selá river valley have a mean 36Cl age of 14.6 ka ± 0.8 ka (n = 4), and the outermost moraine in the valley adjacent to Kaldalónjökull has a mean 36Cl age of 11.7 ka ± 0.9 ka (n = 2). Tephrochronology provides a link between the terrestrial and marine sequences around Vestfirdir. The Vedde Ash (ca. 12 k cal. yr BP) is present in some offshore cores, but it is absent from terrestrial sites, suggesting that its distribution provides a constraint on ice extent during the Younger Dryas. The Saksunarvatn Ash (10.2 ± 0.6 k cal. yr BP), confirmed by geochemical analyses and radiocarbon dating, is present in at least three terrestrial locations on eastern Vestfirdir and in many cores from the fjords and shelf, which constrains early Holocene ice extent. Copyright © 2006 John Wiley & Sons, Ltd.
Toward resolving an earthquake ground motion mystery in west Seattle, Washington State: Shallow seismic focusing may cause anomalous chimney damage

A shallow bedrock fold imaged by a 1.3‐km long high‐resolution shear‐wave seismic reflection profile in west Seattle focuses seismic waves arriving from the south. This focusing may cause a pocket of amplified ground shaking and the anomalous chimney damage observed in earthquakes of 1949, 1965 and 2001. The 200‐m bedrock fold at ∼300‐m depth is caused by deformation across an inferred fault within the Seattle fault zone. Ground motion simulations, using the imaged geologic structure and northward‐propagating north‐dipping plane wave sources, predict a peak horizontal acceleration pattern that matches that observed in strong motion records of the 2001 Nisqually event. Additionally, a pocket of chimney damage reported for both the 1965 and the 2001 earthquakes generally coincides with a zone of simulated amplification caused by focusing. This study further demonstrates the significant impact shallow (<1km) crustal structures can have on earthquake ground‐motion variability.
On the presence of annular variability in an aquaplanet model

Annular mode in the extratropical atmosphere, whether it is dynamically reasonable concept, is examined in the so–called aquaplanet general circulation model. Standard analyses of the empirical orthogonal function (EOF) and one–point correlation to the low–frequency surface pressure anomaly yield results similar to previous studies: the dominant annular mode in EOF but more non–annular distribution in the correlation maps, leading to a difficulty to argue whether the annular structure is a statistical artifact. Similar analyses to the upper–tropospheric streamfunction are, however, able to successfully distinguish the annular mode from a slowly propagating, wavenumber‐five (m = 5) disturbance, both of which are forced by high–frequency eddies. Since the amplitude of the m = 5 waves is weakly interrelated to the annular mode, snapshots of the annular mode extreme tend to accompany large non–annular components. In the aquaplanet experiment with zonally varying boundary condition involved, the annular mode in streamfunction becomes more prevailing, in which the low–frequency eddy itself, in addition to the high–frequency eddies, drives the zonal–mean wind anomaly.
Splash Projection Distance for Aggregated Soils

Splash is an essential process in interrill erosion because it detaches soil fragments from their substrate and transports them. However, splash measurements are difficult to interpret and relatively little is known about the influence of particle characteristics on the spatial distribution of splash. The objective of this work is to study the splash distribution of different size fractions for aggregated soils. We used a recently proposed theory for spatial distribution by splash to interpret experimental data on the radial distribution of soil fragments splashed by simulated rainfall. A laboratory device with five concentric rings was used to determine average splash lengths for 16 fragment size fractions (0.05 to >2000 μm) of four soils. Sieved soil (3- to 5-mm size fraction) was exposed to simulated rainfall at 29 mm h -1 and with a time-specific kinetic energy of 252 J m -2 h -1 . We interpreted the measured masses of fragments splashed into the different rings using an approximate solution of the exponential splash distribution theory applied to the experimental design. We demonstrated that the theory is valid for bulk aggregated soil as well as for individual fragment size fractions. The derived average splash lengths ranged from 4 to 23 cm, depending on the fragment size and soil. Splash lengths were greatest for soil fragments of 100 to 200 μm, and decreased for finer and coarser size fractions. Comparison of these findings with physically-based theory suggests that the coarser fragments, 50 to 2000 μm, are transported as single airborne particles, whereas the smaller ones, <50 μm, are transported in groups in splash droplets. This interpretation is consistent with observations reported in the literature.
Changes in Seasonal Predictability due to Global Warming

AbstractThe change in predictability of monthly mean temperature in a future climate is quantified based on the Community Climate System Model, version 4. According to this model, the North Atlantic overtakes the El Nino–Southern Oscillation (ENSO) as the dominant area of seasonal predictability by 2095. This change arises partly because ENSO becomes less variable and partly because the ENSO teleconnection pattern expands into the Atlantic. Over land, the largest change in temperature predictability occurs in the tropics and is predominantly due to a decrease in ENSO variability. The southern peninsula of Africa and northeast South America are predicted to experience significant drying in a future climate, which decreases the effective heat capacity and memory, and hence increases variance independently of ENSO changes. Extratropical land areas experience enhanced precipitation in a future climate, which decreases temperature variance by the same mechanism. Finally, the model predicts that surface tempera.
Umiujaq, northern Québec: innovative techniques to monitor the decay of a lithalsa in response to climate change

We describe the introduction of several new techniques to measure and monitor permafrost properties at a site near the east coast of the Hudson Bay, northern Québec. Eight boreholes were sunk through a lithalsa to the permafrost base. High precision temperature sensors and a pressure sensor were installed in six boreholes to monitor the long‐time changes of the thermal field of the permafrost and internal pore pressure. Two open boreholes were used to carry out a ground penetrating radar transillumination survey to provide a tomographic image of the spatial distribution of electromagnetic wave velocities within the lithalsa. Cores taken from the permafrost below the active layer of the lithalsa show numerous oblique and fractured ice lenses indicative of extensive deformation of the lithalsa during its evolution. Examples of results of the new techniques applied in this study are provided. These techniques appear as very promising for permafrost studies in general. Copyright © 2003 John Wiley & Sons, Ltd.
Why barren intervals? A taphonomic case study of the Scandinavian Alum Shale and its faunas

The Scandinavian Alum Shale Formation (Middle Cambrian to Lower Ordovician) accumulated under generally low oxygen concentrations. Syndepositional changes in the oxygen concentrations of the bottom water are reconstructed on the basis of the fossil fauna. Under relatively high oxygen concentrations, brachiopods and non-olenid polymerid trilobites inhabited the sea floor. Under lower oxygen concentrations the fauna was dominated by agnostids and at lowest oxygen levels by olenid trilobites. The enrichments of vanadium relative to nickel, as well as the enrichment of sulphur, match these faunal changes. A geochemical classification of the dysoxic environment is presented. The abundance of calcareous fossils decreases with increasing bottom water oxygen concentrations, indicating that the preservation of calcareous hard parts is most likely at the lowest oxygen concentrations. The poor preservation of calcareous fossils at relatively high oxygen concentrations is explained by the generation of corrosive pore waters during the reoxidation of sulphide compounds. Trilobitic and non-trilobitic intervals alternate up through the shale. Non-trilobitic intervals are either barren or contain non-calcareous fossils (phosphatic brachiopods, phosphatic ‘ostracodes’ and graptolites). The stratigraphical variation of trilobitic and non-trilobitic intervals is interpreted to reflect major changes in oxygen levels that might be linked to sea-level and climatic fluctuations.
Constraints on present‐day Basin and Range deformation from space geodesy

We use new space geodetic data from very long baseline interferometry and satellite laser ranging combined with other geodetic and geologic data to study contemporary deformation in the Basin and Range province of the western United States. Northwest motion of the central Sierra Nevada block relative to stable North America, a measure of integrated Basin and Range deformation, is 12.1±1.2 mm/yr oriented N38°W±5° (one standard error), in agreement with previous geological estimates within uncertainties. This velocity reflects both east-west extension concentrated in the eastern Basin and Range and north-northwest directed right lateral shear concentrated in the western Basin and Range. Ely, Nevada is moving west at 4.9±1.3 mm/yr relative to stable North America, consistent with dip-slip motion on the north striking Wasatch fault and other north striking normal faults. Comparison with ground-based geodetic data suggests that most of this motion is accommodated within ∼50 km of the Wasatch fault zone. Paleoseismic data for the Wasatch fault zone and slip rates based on seismic energy release in the region both suggest much lower slip rates. The discrepancy may be explained by some combination of additional deformation away from the Wasatch fault itself, aseismic slip, or a seismic rate that is anomalously low with respect to longer time averages. Deformation in the western Basin and Range province is also largely confined to a relatively narrow boundary zone and in our study area is partitioned into the eastern California shear zone, accommodating 10.7±1.6 mm/yr of north-northwest directed right-lateral shear, and a small component (∼1 mm/yr) of west-southwest - east-northeast extension. A slip rate budget for major strike-slip faults in our study area based on a combination of local geodetic or late Quaternary geologic data and the regional space geodetic data suggests the following rates of right-lateral slip: Owens Valley fault zone, 3.9±1.1 mm/yr; Death Valley-Furnace Creek fault zone, 3.3±2.2 mm/yr; White Mountains fault zone in northern Owens Valley, 3.4±1.2 mm/yr; Fish Lake Valley fault zone, 6.2±2.3 mm/yr. In the last few million years the locus of right-lateral shear in the region has shifted west and become more north trending as slip on the northwest striking Death Valley-Furnace Creek fault zone has decreased and is increasingly accommodated on the north-northwest striking Owens Valley fault zone.
LAND MANAGEMENT STRATEGY FORMULATION IN POST-CONFLICT SOCIETIES

Abstract Developing a sustainable strategic action plan for land management and administration in post-conflict societies is extremely difficult. We will argue that it is not feasible to use conventional conceptual frameworks to underpin strategic action planning in post-conflict environments and, in fact, to do so might prove both inefficient and biased. This argument is based on work in Afghanistan, South Africa, Somalia, Mozambique, Uganda and Kosovo. Instead we argue that a soft systems approach, such as that developed by Barry and Fourie [4] in post-conflict South Africa, should ensure that the most appropriate activities are prioritised. By using examples based on cadastral systems and land administration, we show how a more appropriate strategic action plan for land administration in post-conflict situations can be developed using this framework. This approach should improve both national reconciliation, as well as the efficiency of the land market.
A piecewise linear model for detecting climatic trends and their structural changes with application to mesosphere/lower thermosphere winds over Collm, Germany

[1] A piecewise linear model is developed to detect climatic trends and their structural changes in time series with a priori unknown number and positions of breakpoints (BPs). The departure (i.e., the initial noise term) of trends from time series is allowed to be interpreted by the first- and second-order autoregressive models. The goodness of fit of candidate models, if the residuals are accepted as normally distributed white noise, is evaluated using the Schwarz Bayesian Information Criterion (BIC). The uncertainties of all trend parameters are estimated using the Monte-Carlo method. The model is applied to the mesosphere and lower thermosphere (MLT) winds obtained at Collm, Germany, during 1960–2007. A persistent increase after ∼1980 of the zonal prevailing wind is observed in all seasons and hence in the zonal annual mean based on the primary models. Trends of the meridional prevailing wind are different for different seasons. Several major trend BPs are identified in the annual mean zonal and meridional winds according to BIC. However, in view of the large wind variability before the late 1970s, alternative models are considered. This provides four additional minor breaks. In some cases, the initial noise must be further interpreted by autoregressive models, suggesting that other unidentified factors may also play a role.
The Composite Dikes at Mount Desert Island, Maine: An Example of Coexisting Acidic and Basic Magmas

Composite dikes of Mount Desert Island are composed of pillow-like masses of basalt surrounded by granite and represent coexisting acidic and basic liquids. The contacts between basalt and granite ate sharp on both a megascopic and microscopic scale. Grain-size reduction at basalt pillow margins is generally present and is due to chilling. Evidence of commingling consists of quartz and microcline xenocrysts in the basalt as well as hybrid rocks formed by incomplete mixing of basalt and granite. Rare earth elements in experimental immiscible systems have been shown to be highly partitioned towards the basic liquid ($$D_{b/g} \sim 10$$). In the Mount Desert Island complex, however, the light REE's are enriched in the granite with $$D_{b/g}$$ ranging from 0.48 to 0.67. The REE and petrographie data are incompatible with in situ immiscibility for the origin of these composite dikes.
A multiyear analysis of the relationship between surface environmental variables and NDVI over the Canadian landmass

Abstract The relationships between the normalized difference vegetation index (NDVI) and surface environmental variables are studied across the Canadian landmass using data over a six year period (1982 to 1987). The NDVI images are 15 day composites over the growing season obtained from NOAA AVHRR Global Area Coverage data. Daily climatological surface data in combination with vegetation and soil characterization digital data sets are input into a multilayer soil water budget model to calculate daily amounts of potential evapotranspiration (PE), actual evapotranspiration (AE), and soil moisture. A preliminary study for the year 1986 addressing the above relationships was undertaken by Cihlar et al. (1991). In this study, the stability of the relationships and the effect of a wide range of climatic conditions are investigated. It is found that consistently over the 6 year period, seasonal NDVI trajectories followed PE trends (and AE where water supply was not limiting), lagging by approximately one composi.