Goodbye Gondwana? Questioning disaster triage and fire resilience in Australia     

Lauren Rickards 《The Australian geographer》2016,47(2):127-137

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Metasomatic interactions between slab-derived melts and depleted mantle: Insights from xenoliths within Monglo adakite (Luzon arc, Philippines)   总被引：1，自引：0，他引：1  

M. Gregoire  S. Jego  R.C. Maury  M. Polve  B. Payot  R.A. Tamayo Jr.  G.P. Yumul Jr.   《Lithos》2008,103(3-4):415-430

The Monglo adakite contains mafic and ultramafic xenoliths, which probably originated from the mantle section of an Early Cretaceous supra-subduction zone ophiolitic complex located within the Luzon arc crust. Spinel-bearing dunites are dominant among this xenolith collection and display evidence for three episodes of subduction-related melt percolation. The first one is evidenced by an undeformed clinopyroxene characterized by convex-upwards REE pattern. This clinopyroxene crystallized from a calc-alkaline basaltic magma, likely formed in the Cretaceous supra-subduction setting of the ophiolite. Then, two metasomatic events, evidenced by orthopyroxene-rich and amphibole-rich secondary parageneses, respectively, affected most of the spinel dunites. The opx-rich paragenesis is related to the circulation within the dunitic upper mantle of hydrous slab-derived melts similar to those affecting the mantle peridotite xenoliths from Papua New Guinea and Kamchatka. Finally the amphibole-rich veins are related to the interaction between the studied dunite xenoliths and the host adakite or an adakitic melt similar to it.  相似文献   

Shifts in the thermal niche of almond under climate change     

Lauren E. Parker  John T. Abatzoglou 《Climatic change》2018,147(1-2):211-224

Delineating geographic shifts in crop cultivation under future climate conditions provides information for land use and water management planning, and insights to meeting future demand. A suitability modeling approach was used to map the thermal niche of almond cultivation and phenological development across the Western United States (US) through the mid-21st century. The Central Valley of California remains thermally suitable for almond cultivation through the mid-21st century, and opportunities for expansion appear in the Willamette Valley of western Oregon, which is currently limited by insufficient heat accumulation. Modeled almond phenology shows a compression in reproductive development under future climate. By the mid-21st century, almond phenology in the Central Valley showed ~?2-week delay in chill accumulation and ~?1- and ~?2.5-week advance in the timing of bloom and harvest, respectively. Although other climatic and non-climatic restrictions to almond cultivation may exist, these results highlight opportunities for shifts in the geography of high-value cropping systems, which may influence growers’ long-term land use decisions, and shape regional water and agricultural industry discussions regarding climate change adaptation options.  相似文献   

Thermal Property Measurements of Stratigraphic Units with Modeled Implications for Expected Performance of Vertical Ground Source Heat Pumps     

Matthew D. Walker  Lauren L. Meyer  James M. Tinjum  David J. Hart 《Geotechnical and Geological Engineering》2015,33(2):223-238

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Drought adaptation policy development and assessment in East Africa using hydrologic and system dynamics modeling   总被引：2，自引：0，他引：2  

Lauren Gies  Datu Buyung Agusdinata  Venkatesh Merwade 《Natural Hazards》2014,74(2):789-813

Drought is a natural disaster that affects millions of people across the globe. Lack of rainfall reduces crop yields and livestock productivity and, in turn, food availability and income. In developing countries, these effects are even more detrimental. As droughts become more frequent, adaptation is a fundamental concern for countries and their policymakers. To support a development of drought adaptation policies, a combined hydrologic and system dynamics model was developed for a region in East Africa, focused on the Horn of Africa (i.e., a region bordering Kenya, Somalia, and Ethiopia), an area that has endured multiple droughts in the last few decades. The model simulates the interdependencies between water availability, land degradation, food availability, and socioeconomic welfare. The impacts of new adaptation policies on the region were evaluated over a 10-year simulation period using historical weather data. It was found that a combination of increased hydraulic infrastructure and innovative agricultural practice policy can reduce domestic water deficits by 54–100 % while increasing the income per capita up to 285 % over the 10 years. Innovatively combining hydrologic and systems dynamic modeling produces a realistic simulation of water scarcity and the effects on natural systems. Implementation of policies within the model aids the selection process by evaluating multiple options, quantifying the effectiveness the policies have on individual stakeholder livelihood (i.e., pastoralist, agro-pastoralists, and farmers), and analyzing the overall outcome to ensure equitable costs and benefits among the stakeholders.  相似文献   

USGS46 Greenland Ice Core Water – A New Isotopic Reference Material for δ2H and δ18O Measurements of Water     

Tyler B. Coplen  Haiping Qi  Lauren Tarbox  Jennifer Lorenz  Bryan Buck 《Geostandards and Geoanalytical Research》2014,38(2):153-157

Ice core from Greenland was melted, filtered, homogenised, loaded into glass ampoules, sealed, autoclaved to eliminate biological activity, and calibrated by dual‐inlet isotope‐ratio mass spectrometry. This isotopic reference material (RM), USGS46, is intended as one of two secondary isotopic reference waters for daily normalisation of stable hydrogen (δ²H) and stable oxygen (δ¹⁸O) isotopic analysis of water with a mass spectrometer or a laser absorption spectrometer. The measured δ²H and δ¹⁸O values of this reference water were ?235.8 ± 0.7‰ and ?29.80 ± 0.03‰, respectively, relative to VSMOW on scales normalised such that the δ²H and δ¹⁸O values of SLAP reference water are, respectively, ?428 and ?55.5‰. Each uncertainty is an estimated expanded uncertainty (U = 2u_c) about the reference value that provides an interval that has about a 95‐percent probability of encompassing the true value. This reference water is available in cases containing 144 glass ampoules that are filled with either 4 ml or 5 ml of water per ampoule.  相似文献   

Petrogenesis of Fe–Ti oxides in amphibole-rich veins from the Lherz orogenic peridotite (Northeastern Pyrénées, France)     

Jean-Pierre Lorand  Michel Gregoire 《Contributions to Mineralogy and Petrology》2010,160(1):99-113

Accessory, homogeneous ilmenite and rutile are important oxide phases in amphibole-rich high-pressure cumulate veins which crosscut the Lherz orogenic lherzolite massif. Those veins crystallized from alkaline melts at P = 1.2–1.5 GPa within the uppermost lithospheric mantle. Transitional basalts contaminated by peridotitic wall-rocks and then uncontaminated alkali basalts (basanites) reused the same vein conduits. Petrographic observations give evidence that Fe–Ti oxide saturation depends on the silica contents of each parental melt. The water-poor silica-rich transitional melts that generated websterites and plagioclase-rich clinopyroxenites reached early Ti-oxide saturation (1,200°C; 1.5 GPa). Rutile is as abundant as ilmenite. It is enriched with Nb–Zr–Hf by a factor of 10–100 relative to either amphibole or ilmenite. The amphibole pyroxenites and hornblendites crystallized from basanites reached late Fe–Ti oxide saturation after precipitation of amphibole, with ilmenite crystallizing along with phlogopite in the latter. The Lherz ilmenites are devoid of exsolution and contain very little trivalent iron. This compositional feature indicates more reducing crystallization conditions than usually inferred for alkali lavas and their megacrysts (FMQ ± 1). The veins incompletely equilibrated for redox conditions with their wall-rock peridotites which record more oxidizing conditions (FMQ ± 1). The veins also exchanged magnesium and chromium, as suggested by Cr-bearing, Mg-rich ilmenite (up to 44 mol% MgTiO₃₎ in veins less than 3–4 cm thick. Mg-rich ilmenite megacrysts occurring in alkali basalts could be actually xenocrysts from veins similar in thickness to those occurring at the Lherz massif, although crystallized from more oxidized magmas.  相似文献   

Modeling aqueous alteration of CM carbonaceous chondrites     

Nina D. ROSENBERG  Lauren BROWNING  William L. BOURCIER 《Meteoritics & planetary science》2001,36(2):239-244

Abstract— Results from an inorganic geochemical modeling study support a scenario in which low‐temperature aqueous alteration of an anhydrous CM asteroidal parent body and melt water from H₂O and CO₂ ices produces the altered assemblage observed in CM carbonaceous chondrites (chrysotile, greenalite, tochilinite, cronstedtite and minor calcite and magnetite). We consider a range of possible precursor mineral assemblages, varying with respect to the Fe‐oxidation state of the initial anhydrous phases. The aqueous solutions produced by this alteration are generally strongly basic and reducing and a large quantity of H₂, and possible CH₄, gas can be released during aqueous alteration.  相似文献   

Adaptive governance and the human dimensions of marine mammal management: Implications for policy in a changing North     

Chanda L. Meek  Amy Lauren Lovecraft  Riku Varjopuro  Martha Dowsley  Aaron T. Dale 《Marine Policy》2011

As climate change has driven dramatic changes in Northern sea ice regimes, marine mammals have gained iconic status around the world reflecting the perils of global warming. There is a tension between policies that have international support like a ban on seal hunting or whaling, and the adoption of adaptive, flexible rules that are likely to work in Northern places. Whereas most wildlife policy focuses on biological information to inform policy strategy, this analysis focuses on the “human dimensions” of Northern marine mammal management. This research examines ways in which human relationships and modes of governance affect conservation success. Standard analyses of risk to animal populations focused on direct sources of take are inadequate to address multi-causal, complex problems such as climate-induced habitat loss or increased industrialization of the Arctic Ocean. Early conservation policy strategies focusing on the moratorium of take have eliminated or reduced such practices as commercialized hunting and high levels of fisheries bycatch, but may be less relevant in an era in which habitats and climate changes are key drivers of population dynamics. This paper argues that effective adaptive policy requires new ways of learning about and governing human interactions with marine mammals. Through an exploration of marine mammal management in three Northern regions (Alaska, Nunavut, and the Finnish Baltic Sea coast), the paper analyzes the extent to which these marine mammal management regimes are practicing adaptive governance, that is, building cross-scale (local to international) understanding while allowing actors at the local scale the flexibility to direct the creation of rules that are ecologically robust and likely to succeed. Lessons are taken from these examples and used to propose selected policy and research recommendations for the marine mammal policy community.  相似文献   

The human dimensions of marine mammal management in a time of rapid change: comparing policies in Canada,Finland and the United States     

Amy Lauren Lovecraft  Chanda L. Meek 《Marine Policy》2011

Arctic coastal populations share a close relationship with their environment consisting of linkages among communities, landscapes and seascapes, and the social institutions developed to sustain the system. This cultural–biogeophysical dynamic is termed throughout the section as a social–ecological system (SES). Marine mammals constitute a large portion of the subsistence diet for these communities, and as such represent key ecological services provided by the system. At the same time, marine mammals have gained iconic status as symbols for climate change in the North. A tension results between the demands of balancing on one hand good policy optics consistent with national and international norms and, on the other hand, flexible and adaptive institutions able to take on the task of managing resources in a dynamic, changing North. This tension and associated policy solutions such as co-management are explored in a series of papers focusing on marine mammal management dilemmas and policy practices around the circumpolar North. This introduction communicates the problem context and describes the five papers making up this special section. A guiding premise to this work is that new international pressures to implement moratoria on marine mammal hunting in the North ignore critical human dimensions of marine mammal management. Such policy proposals are unlikely to succeed in areas that require collaboration across scales. Simultaneously, new local-scale participation in multi-level management regimes holds promise for creating more resilient marine mammal SESs.  相似文献