Holocene environmental history of thermokarst lakes on Richards Island, Northwest Territories, Canada: Theocamoebians as paleolimnological indicators     

Audrey Dallimore  Claudia J. Schröder-Adams  Scott R. Dallimore 《Journal of Paleolimnology》2000,23(3):261-283

Richards Island, Northwest Territories, Canada, is characterized by thermokarst lakes which record Holocene limnological change. This study is the first report of thecamoebian assemblages and continuous annual lake water temperatures from these Arctic lakes. Ecological environments on Richards Island are influenced by a climatic gradient resulting from the contrasting influences of the cold Beaufort Sea to the north and the warm waters of the Mackenzie Delta to the east and west. This climatic gradient in turn influences modern thecamoebian assemblages, and is an indication of the complexity involved in interpreting past conditions from core material in this area.Population abundance and species diversity of thecamoebian assemblages on Richards Island are not significantly different from those reported from temperate and semi-tropical latitudes. However, certain assemblage characteristics, such as large and coarse agglutinated tests, dominance of assemblages by one or two species and low morphological variation are interpreted to be diagnostic of Arctic conditions. Thecamoebian assemblages in core material from the area indicate that the local paleolimnological conditions may have changed within the last 3 ka, and this is unrecorded in previously reported pollen data.Paleoenvironmental interpretations in a permafrost landscape have to take into account morphological instability of thermokarst lakes, which can be the cause of paleolimnological and consequently faunal change. In this area ecosystem development is clearly related to geomorphology and local climatic effects and is not exclusively controlled by regional climate change.  相似文献   

On computation of conditional mean spectrum in Eastern Canada   总被引：2，自引：2，他引：0  

Poulad Daneshvar  Najib Bouaanani  Audrey Godia 《Journal of Seismology》2015,19(2):443-467

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Exhumed hydrocarbon traps on the North Atlantic margin: Stratigraphy,palaeontology, provenance and bitumen distribution,an integrated approach     

Steven D. Andrews  Audrey Decou  Bill Braham  Simon R. A. Kelly  Paula Robinson  Andrew C. Morton  John E. A. Marshall  Fiona Hyden 《Basin Research》2020,32(5):1213-1233

Previous work has demonstrated the presence of a number of exhumed hydrocarbon traps in central East Greenland. Re-evaluation of the stratigraphy alongside detailed investigation of the occurrence of bitumen within the Mols Bjerge and Laplace Bjerg exhumed hydrocarbon traps provides new perspectives on these structures, as well as the petroleum geology of East Greenland and the wider North Atlantic. Sedimentological and stratigraphic studies, augmented with palynological and provenance investigations, have constrained the dating and correlation of the strata exposed in the Mols Bjerge and Laplace Bjerg. Petrographic analysis, alongside analysis of the bitumen identified, has highlighted a much wider distribution of hydrocarbon than previously recognized. It was previously considered that Jurassic strata formed the main reservoir interval within the Mols Bjerge and Laplace Bjerg exhumed hydrocarbon traps. It is shown here that the reservoir intervals in the Laplace Bjerg trap lie within the Late Triassic Ørsted Dal and Vega Sund members, which contain up to 18% pyrobitumen and were previously misidentified as Jurassic. The Jurassic Bristol Elv Formation is the most extensively bitumen stained unit in the Mols Bjerge trap. However, occurrences of pyrobitumen (up to 3%) are recorded throughout the Triassic stratigraphy, including the Early Triassic Wordie Creek Formation. Faults, thick calcrete development and regionally continuous mudstone units play an important role in compartmentalizing the palaeohydrocarbon accumulations.  相似文献   

Unpacking ‘Success’: Applying Local Perceptions to Interpret Influences of Water Fund Payments for Ecosystem Services in the Ecuadorian Andes     

Audrey J. Joslin 《社会与自然资源》2019,32(6):617-637

NGOs, government agencies, and green businesses proclaim water fund arrangements in Latin America as successful payments for ecosystem services (PES) systems. Associated success narratives emphasize that PES allows downstream ecosystem service beneficiaries to incentivize upstream land managers to pursue conservation activities. However, recent scholarship questions their on-the-ground influence. This article assesses the success narrative of Quito, Ecuador’s Fondo para la protección del Agua’s (FONAG) as a model water fund PES arrangement. Using a novel perceived directionality framework, the author compares the FONAG claims about its influence to ethnographic evidence from three participating rural communities. The findings suggest that statements of direct, causal influence on local conservation activities overlook local context and ignores nuance within the interactions between program incentives and in community activity. This study urges future assessments of PES arrangements to recognize complexities in political, economic, and social context.  相似文献   

The Meteoritical Bulletin,No. 106     

Jrme Gattacceca  Audrey Bouvier  Jeffrey Grossman  Knut Metzler  Minoru Uehara 《Meteoritics & planetary science》2019,54(2):469-471

Meteoritical Bulletin 106 contains 1868 meteorites including 10 falls (Aiquile, Broek in Waterland, Degtevo, Dingle Dell, Dishchii'bikoh, Hradec Králové, Kheneg Ljouâd, Oudiyat Sbaa, Serra Pelada, Tres Irmaos), with 1386 ordinary chondrites, 166 carbonaceous chondrites, 119 HED achondrites, 48 Lunar meteorites, 37 iron meteorites, 36 ureilites, 19 Martian meteorites, 13 enstatite chondrites, 12 Rumuruti chondrites, 9 primitive achondrites, 8 mesosiderites, 5 enstatite achondrites, 4 ungrouped achondrites, 4 pallasites, and 1 relict meteorite. A total of 958 meteorites are from Africa, 405 from Antarctica, 245 from Asia, 228 from South America, 12 from North America, 8 from Europe, 5 from Mars, 4 from Oceania, and 1 from an unknown location.  相似文献   

The Meteoritical Bulletin,No. 104          下载免费PDF全文

Audrey Bouvier  Jérôme Gattacceca  Carl Agee  Jeffrey Grossman  Knut Metzler 《Meteoritics & planetary science》2017,52(10):2284-2284

Meteoritical Bulletin 104 contains 2279 meteorites including 12 falls (Annama, Cartersville, Creston, Diepenveen, Famenin, Izarzar, Nkayi, Porangaba, San Juan de Ocotán, Trâpe?ng Rôno?s, Xinglongquan, ?d’ár nad Sázavou), with 1847 ordinary chondrites, 138 carbonaceous chondrites, 128 HED achondrites, 38 lunar meteorites, 24 ureilites, 22 Martian meteorites, 19 iron meteorites, 17 primitive achondrites, 14 enstatite chondrites, 10 mesosiderites, 9 Rumuruti chondrites, 5 pallasites, 4 ungrouped achondrites, 2 enstatite achondrites, 1 ungrouped chondrite, and 1 Kakangari chondrite, and with 996 from Antarctica, 790 from Africa, 337 from Asia, 111 from South America, 30 from North America, 11 from Oceania, and 4 from Europe. Note: 1 meteorite from Russia was counted as European.  相似文献   

Development of Atlantic cod (Gadus morhua) exposed to produced water during early life stages: Effects on embryos, larvae, and juvenile fish     

Sonnich Meier  H. Craig Morton  Gunnar Nyhammer  Bjrn Einar Grsvik  Valeri Makhotin  Audrey Geffen  Stepan Boitsov  Karen Anita Kvestad  Anneli Bohne-Kjersem  Anders Goksyr  Arild Folkvord  Jarle Klungsyr  Asbjrn Svardal 《Marine environmental research》2010,70(5):383-394

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Time‐lapse electrical resistivity imaging of solute transport in a karst conduit          下载免费PDF全文

Audrey H. Sawyer  Junfeng Zhu  James C. Currens  Clay Atcher  Andrew Binley 《水文研究》2015,29(23):4968-4976

The use of electrical resistivity surveys to locate karst conduits has shown mixed success. However, time‐lapse electrical resistivity imaging combined with salt injection improves conduit detection and can yield valuable insight into solute transport behaviour. We present a proof of concept above a known karst conduit in the Kentucky Horse Park (Lexington, Kentucky). A salt tracer solution was injected into a karst window over a 45‐min interval, and repeat resistivity surveys were collected every 20 min along a 125‐m transect near a monitoring well approximately 750 m downgradient from the injection site. In situ fluid conductivity measurements in the well peaked at approximately 25% of the initial value about 3 h after salt injection. Time‐lapse electrical resistivity inversions show two broad zones at the approximate conduit depth where resistivity decreased and then recovered in general agreement with in situ measurements. Combined salt injection and electrical resistivity imaging are a promising tool for locating karst conduits. The method is also useful for gaining insight into conduit geometry and could be expanded to include multiple electrical resistivity transects. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Geochemistry and chronology of the Bunburra Rockhole ungrouped achondrite          下载免费PDF全文

Lev J. Spivak‐Birndorf  Audrey Bouvier  Gretchen K. Benedix  Samantha Hammond  Gregory A. Brennecka  Kieren Howard  Nick Rogers  Meenakshi Wadhwa  Philip A. Bland  Pavel Spurný  Martin C. Towner 《Meteoritics & planetary science》2015,50(5):958-975

Bunburra Rockhole is a unique basaltic achondrite that has many mineralogical and petrographic characteristics in common with the noncumulate eucrites, but differs in its oxygen isotope composition. Here, we report a study of the mineralogy, petrology, geochemistry, and chronology of Bunburra Rockhole to better understand the petrogenesis of this meteorite and compare it to the eucrites. The geochemistry of bulk samples and of pyroxene, plagioclase, and Ca‐phosphate in Bunburra Rockhole is similar to that of typical noncumulate eucrites. Chronological data for Bunburra Rockhole indicate early formation, followed by slow cooling and perhaps multiple subsequent heating events, which is also similar to some noncumulate eucrites. The ²⁶Al‐²⁶Mg extinct radionuclide chronometer was reset in Bunburra Rockhole after the complete decay of ²⁶Al, but a slight excess in the radiogenic ²⁶Mg in a bulk sample allows the determination of a model ²⁶Al‐²⁶Mg age that suggests formation of the parent melt for this meteorite from its source magma within the first ~3 Ma of the beginning of the solar system. The ²⁰⁷Pb‐²⁰⁶Pb absolute chronometer is also disturbed in Bunburra Rockhole minerals, but a whole‐rock isochron provides a re‐equilibration age of ~4.1 Ga, most likely caused by impact heating. The mineralogy, geochemistry, and chronology of Bunburra Rockhole demonstrate the similarities of this achondrite to the eucrites, and suggest that it formed from a parent melt with a composition similar to that for noncumulate eucrites and subsequently experienced a thermal history and evolution comparable to that of eucritic basalts. This implies the formation of multiple differentiated parent bodies in the early solar system that had nearly identical bulk elemental compositions and petrogenetic histories, but different oxygen isotope compositions inherited from the solar nebula.  相似文献   

A GIS‐based Vehicle Mobility Estimator for Operational Contexts     

Audrey Hohmann  Gilles Grandjean  Vincent Mardhel  Gilles Schaefer  Nicolas Desramaut 《Transactions in GIS》2013,17(1):78-95

A vehicle mobility estimator has been developed to produce decision aid maps for projecting civil or military forces on operational theatres. Based on the exploitation of classical geographical sources (e.g. digital elevation models, optical images, and vector databases) and thematic sources (e.g. climate, meteorological, pedological and land cover databases), the system computes speed maps for different kinds of vehicles moving both on‐road and off‐road. Such computations are realized through a ground‐vehicle interaction module that estimates the vehicle performance from experimental results, numerical simulations and empirical relationships. The system's architecture is built using a GIS interface that manages the data, the computation and the presentation layers. An operational version of this tool has been tested and validated on several operational theatres in France and in northern Africa. The results show good agreement between the predicted mobility performance of various vehicles and those observed on the field. A case study is presented to illustrate the mobility maps and demonstrate their relevance in the decision‐making chain depending on different climate contexts. A short application to itinerary optimization is presented as a promising future application.  相似文献