Quantitative Relationships Between Basalt Geochemistry, Shear Wave Velocity, and Asthenospheric Temperature Beneath Western North America

©2018. American Geophysical Union. All Rights Reserved. Western North America has an average elevation that is ∼2 km higher than cratonic North America. This difference coincides with a westward decrease in average lithospheric thickness from ∼240 to 260 basaltic samples. Forward and inverse modeling of carefully selected major, trace, and rare earth elements were used to determine melt fraction as a function of depth. Basaltic melt appears to have been generated by adiabatic decompression of dry peridotite with asthenospheric potential temperatures of 1340 ± 20 °C. Potential temperatures as high as 1365 °C were obtained for the Snake River Plain. For the youngest (i.e., <5 Ma) basalts with a subplate geochemical signature, there is a positive correlation between shear wave velocities and trace element ratios such as La/Yb. The significance of this correlation is explored by converting shear wave velocity into temperature using a global empirical parameterization. Calculated temperatures agree with those determined by inverse modeling of rare earth elements. We propose that regional epeirogenic uplift of western North America is principally maintained by widespread asthenospheric temperature anomalies lying beneath a lithospheric plate, which is considerably thinner than it was in Late Cretaceous times. Our proposal accounts for the distribution and composition of basaltic magmatism and is consistent with regional heat flow anomalies

Thermal Structure of Eastern Australia's Upper Mantle and Its Relationship to Cenozoic Volcanic Activity and Dynamic Topography

Funder: Geoscience AustraliaFunder: Shell Global, Shell Exploration and Production Company; Id: http://dx.doi.org/10.13039/100011092Abstract: Spatio‐temporal changes of upper mantle structure play a significant role in generating and maintaining surface topography. Although geophysical models of upper mantle structure have become increasingly refined, there is a paucity of geologic constraints with respect to its present‐day state and temporal evolution. Cenozoic intraplate volcanic rocks that crop out across eastern Australia provide a significant opportunity to quantify mantle conditions at the time of emplacement and to independently validate geophysical estimates. This volcanic activity is divided into two categories: age‐progressive provinces that are generated by the sub‐plate passage of mantle plumes and age‐independent provinces that could be generated by convective upwelling at lithospheric steps. In this study, we acquired and analyzed 78 samples from both types of provinces across Queensland. These samples were incorporated into a comprehensive database of Australian Cenozoic volcanism assembled from legacy analyses. We use geochemical modeling techniques to estimate mantle temperature and lithospheric thickness beneath each province. Our results suggest that melting occurred at depths ≤80 km across eastern Australia. Prior to, or coincident with, onset of volcanism, lithospheric thinning as well as dynamic support from shallow convective processes could have triggered uplift of the Eastern Highlands. Mantle temperatures are inferred to be ∼50–100°C hotter beneath age‐progressive provinces that demarcate passage of the Cosgrove mantle plume than beneath age‐independent provinces. Even though this plume initiated as one of the hottest recorded during Cenozoic times, it appears to have thermally waned with time. These results are consistent with xenolith thermobarometric and geophysical studies

Bounded Temporal Fairness for FIFO Financial Markets

Financial exchange operators cater to the needs of their users while simultaneously ensuring compliance with the financial regulations. In this work, we focus on the operators' commitment for fair treatment of all competing participants. We first discuss unbounded temporal fairness and then investigate its implementation and infrastructure requirements for exchanges. We find that these requirements can be fully met only under ideal conditions and argue that unbounded fairness in FIFO markets is unrealistic. To further support this claim, we analyse several real-world incidents and show that subtle implementation inefficiencies and technical optimizations suffice to give unfair advantages to a minority of the participants. We finally introduce, {\epsilon}-fairness, a bounded definition of temporal fairness and discuss how it can be combined with non-continuous market designs to provide equal participant treatment with minimum divergence from the existing market operation

A Strategic Environmental Management Model: Salt Lake Case

Strategic Environmental Management Plan (SEMP) is the most important tool used to determine how to protect, to use, to develop and to manage regions. SEMP is prepared for the identification of natural and cultural resources, identifying threats to those resources, and the long term protection of the region and it also provides development of strategies and implementation plans. Within SEMP is based on the current state of the region and it shows the most efficient and equitable way to be achieved in the future. The article aims to correctly analyse Salt Lake's unique environmental conditions and protect its biological endogenous and exogenous factors that may arise in the future. In this paper, it is also developed creative and innovative approaches to use and to protect existing stocks by establishing a major paradigm to carry these approaches into future. The model includes four dimensions. First the problems of Salt Lake is determined in consideration of four dimensions such as environment, agriculture and livestock, business world and management issues then a scale is developed according to results obtained from focus group meetings. Stakeholders of Salt Lake evaluate each component of the region -economic condition, biological, ecological and social values, protection of environment, and regional management issues -. Finally, a strategic environmental management model is developed special to Salt Lake. (C) 2014 The Authors. Published b

Stofftransportmodellierung im Sicker- und Grundwasser

Entwickelt wurde eine Konzeption zur Erstellung und Pilotanwendung eines gekoppelten Modellsystems für Sicker- und Grundwasser (ReArMo), das die prognostische Abschätzung künftiger Entwicklungen des Grundwassers nach Menge und Beschaffenheit unter geänderten Randbedingungen (Klima, Landnutzung, Bewirtschaftung) zum Ziel hat. Ein weiteres Ziel dieser Modellkopplung besteht in der Optimierung der Stickstoffdüngung bei relevanten landwirtschaftlichen Betrieben. Die zu betrachtenden Prozesse in der wechselfeuchten Bodenzone und im Grundwasser werden gemäß dem aktuellen Stand der Technik physikalisch fundiert erfasst

A tale of two domes: Neogene to recent volcanism and dynamic uplift of northeast Brazil and southwest Africa

Topographic domes that are located far from active plate boundaries are often characterised by rapid, youthful uplift, contemporaneous mafic volcanism, radial drainage patterns, and positive long-wavelength gravity anomalies. There is increasing evidence that they are underlain by anomalously low sub-plate seismic velocities. Despite their well-known geomorphological expression, the origin of these epeirogenic features remains enigmatic and is much debated. Here, we investigate potential mechanisms of uplift by combining disparate observations from the Borborema and Angolan plateaux that straddle the Brazilian and southwest African margins, respectively. Oceanic residual depth measurements, drainage analysis, stratigraphic architecture, emergent marine terraces and basement denudation are used to constrain their regional uplift histories. In both cases, the bulk of topographic growth occurred within the last 30 Ma in the absence of significant tectonic deformation. We derive present-day mantle temperature and lithospheric thickness from Neogene to recent volcanic trace element compositions and upper mantle shear wave velocities. Volcanic geochemistry in northeast Brazil is compatible with decompression melting of warm asthenosphere and potentially a minor contribution from metasomatised lithospheric mantle. In Angola, melting of metasomatised lithosphere is most likely triggered by injection of small-degree asthenospheric-derived melts. We find no evidence for an asthenospheric thermal anomaly > 50 ◦ C above ambient beneath either region. Present-day lithospheric thickness is ∼ 100 km beneath Angola and could be as thin as 60 km in the Borborema Province. For Angola, thermobarometry on mantle xenocrysts from Cretaceous kimberlites is used to estimate palaeogeothermal gradients. Results indicate a pre- existing gradient in lithospheric thickness between the edge of the Congo craton and the centre of the Angolan dome at ∼ 120 Ma. This gradient likely steepened as a result of additional Neogene thinning by ∼ 30 ± 10 km beneath the centre of the dome. We conclude that the mechanism for Neogene epeirogenic uplift of the Borborema and Angolan domes is introduction of a small positive temperature anomaly into the asthenosphere that causes thermomechanical thinning of the overlying lithospheric mantle

KliWES 2.0 – Klimawandel und Wasserhaushalt: Methodikoptimierung der Wasserhaushaltsmodellierung, Fortschreibung von Modelleingangsdaten, sachsenweite Wasserhaushaltsmodellierung für Ist-Zustand und Szenarien sowie Weiterentwicklung der KliWES-Internetanwendung im Wasserhaushaltsportal Sachsen

Die Schriftenreihe informiert über die Fortschreibung des Projektes „Klimawandel und Wasserhaushalt in Sachsen“ (KlIWES-2.0) mit einem weiterentwickelten ARCEGMO- Modell- Konzept. Zunächst erfolgte eine Neuberechnung des IST- Wasserhaushaltes bis 2015. Ergänzend wurden mit acht ausgewählten WEREX-VI- Klima- Realisierungen künftige Wasserhaushalts- Entwicklungen (bis 2100) modelliert. Die Ergebnisse zeigen überwiegend ein weiter abnehmende Abfluss- Dargebots- Entwicklung in den Gewässereinzugsgebieten. Über das neue Anwendungs- Tool „KliWES-2.0“ sind die Ergebnisse im „Wasserhaushaltsportal Sachsen“ für einen breiten Nutzerkreis auch webbasiert verfügbar. Redaktionsschluss: 10.06.202