94 research outputs found
Canadian Sovereignty Linked to Energy Development in the Arctic
INDUSTRY IS ABOUT TO EMBARK SERIOUSLY on explorationand probable development of Canada’s Arctic energyresources. The price of natural gas has recovered from its recent lows and is now on the upswing, with no end in sight. With conventional natural gas production already in decline in the mature Western Canada Sedimentary Basin, no one can predict when and where the price of gas will stabilize. Oil has long passed the 140 a barrel, getting ever closer, in absolute dollars, to levels not reached since the oil shocks of the 1970s. The world’s largest oilfields are in decline, starting with Saudi Arabia’s mammoth Ghawar field, one of many giant oil pools from Mexico, Russia, and the Middle East discovered during the heyday of hydrocarbon exploration in the 1960s and 1970s. Con-ventional supplies are declining as China and India grow at breakneck pace, and our American neighbour shows n
Mercury anomalies associated with three extinction events (Capitanian Crisis, Latest Permian Extinction and the Smithian/Spathian Extinction) in NW Pangea
Copyright © Cambridge University Press 2015. Strata of Permian - Early Triassic age that include a record of three major extinction events (Capitanian Crisis, Latest Permian Extinction and the Smithian/Spathian Extinction) were examined at the Festningen section, Spitsbergen. Over the c. 12 Ma record examined, mercury in the sediments shows relatively constant background values of 0.005-0.010 μg g -1 . However, there are notable spikes in Hg concentration over an order of magnitude above background associated with the three extinctions. The Hg/total organic carbon (TOC) ratio shows similar large spikes, indicating that they represent a true increase in Hg loading to the environment. We argue that these represent Hg loading events associated with enhanced Hg emissions from large igneous province (LIP) events that are synchronous with the extinctions. The Hg anomalies are consistent across the NW margin of Pangea, indicating that widespread mercury loading occurred. While this provides utility as a chemostratigraphic marker the Hg spikes may also indicate loading of toxic metals to the environment, a contributing cause to the mass extinction events
An abrupt extinction in the Middle Permian (Capitanian) of the Boreal Realm (Spitsbergen) and its link to anoxia and acidification
The controversial Capitanian (Middle Permian, 262 Ma) extinction event is only known from equatorial latitudes, and consequently its global extent is poorly resolved. We demonstrate that there were two, severe extinctions amongst brachiopods in northern Boreal latitudes (Spitsbergen) in the Middle to Late Permian, separated by a recovery phase. New age dating of the Spitsbergen strata (belonging to the Kapp Starostin Formation), using strontium isotopes and d13C trends and comparison with better-dated sections in Greenland, suggests that the first crisis occurred in the Capitanian. This age assignment indicates that this Middle Permian extinction is manifested at higher latitudes. Redox proxies (pyrite framboids and trace metals) show that the Boreal crisis coincided with an intensification of oxygen depletion, implicating anoxia in the extinction scenario. The widespread and near-total loss of carbonates across the Boreal Realm also suggests a role for acidification in the crisis. The recovery interval saw the appearance of new brachiopod and bivalve taxa alongside survivors, and an increased mollusk dominance, resulting in an assemblage reminiscent of younger Mesozoic assemblages. The subsequent end-Permian mass extinction terminated this Late Permian radiation
Life Beneath Glacial Ice - Earth(!) Mars(?) Europa(?)
We are investigating a set of cold springs that deposit sulfur and carbonate minerals on the surface of a Canadian arctic glacier. The spring waters and mineral deposits contain microorganisms, as well as clear evidence that biological processes mediate subglacial chemistry, mineralogy, and isotope fractionation . The formation of native sulphur and associated deposits are related to bacterially mediated reduction and oxidation of sulphur below the glacier. A non-volcanic, topography driven geothermal system, harboring a microbiological community, operates in an extremely cold environment and discharges through solid ice. Microbial life can thus exist in isolated geothermal refuges despite long-term subfreezing surface conditions. Earth history includes several periods of essentially total glaciation. lee in the near subsurface of Mars may have discharged liquid water in the recent past Cracks in the ice crust of Europa have apparently allowed the release of water to the surface. Chemolithotrophic bacteria, such as those in the Canadian springs, could have survived beneath the ice of "Snowball Earth", and life forms with similar characteristics might exist beneath the ice of Mars or Europa. Discharges of water from such refuges may have brought to the surface living microbes, as well as longlasting chemical, mineralogical, and isotopic indications of subsurface life
Global warming leads to Early Triassic nutrient stress across northern Pangea
The largest extinction in Earth history, in the latest Permian, was followed throughout most of the Early Triassic by a prolonged period of ecologic recovery. What factors delayed biotic recovery are still under debate and partly revolve around impacts of global warming on primary marine productivity. We examined N isotope records from the Festningen section on Spitsbergen, Arctic Norway, to examine changes in nutrient availability through the Early to Middle Triassic along the northern margin of Pangea. Our results show progressive decline in N availability throughout the Griesbachian, leading to severe nutrient limitations through the remainder of the Early Triassic, until returning to a highly productive continental margin in Middle Triassic time. These results are consistent with other studies from northern and western Pangea and thus show regional nutrient limitations occurred in what should have been the main zone of marine primary productivity. Such nutrient limitation likely stressed primary production and consequently contributed to prolonged marine recovery. We suggest this was driven by high ocean temperatures depressing the marine nutricline
Ultra-shallow-marine anoxia in an Early Triassic shallow-marine clastic ramp (Spitsbergen) and the suppression of benthic radiation
Lower Triassic marine strata in Spitsbergen accumulated on a mid-to-high latitude ramp in which high-energy foreshore and shoreface facies passed offshore into sheet sandstones of probable hyperpycnite origin. More distal facies include siltstones, shales and dolomitic limestones. Carbon isotope chemostratigraphy comparison allows improved age dating of the Boreal sections and shows a significant hiatus in the upper Spathian. Two major deepening events, in earliest Griesbachian and late Smithian time, are separated by shallowing-upwards trends that culminated in the Dienerian and Spathian substages. The redox record, revealed by changes in bioturbation, palaeoecology, pyrite framboid content and trace metal concentrations, shows anoxic phases alternating with intervals of better ventilation. Only Dienerian–early Smithian time witnessed persistent oxygenation that was sufficient to support a diverse benthic community. The most intensely anoxic, usually euxinic, conditions are best developed in offshore settings, but at times euxinia also developed in upper offshore settings where it is even recorded in hyperpycnite and storm-origin sandstone beds: an extraordinary facet of Spitsbergen's record. The euxinic phases do not track relative water depth changes. For example, the continuous shallowing upwards from the Griesbachian to lower Dienerian was witness to several euxinic phases separated by intervals of more oxic, bioturbated sediments. It is likely that the euxinia was controlled by climatic oscillations rather than intra-basinal factors. It remains to be seen if all the anoxic phases found in Spitsbergen are seen elsewhere, although the wide spread of anoxic facies in the Smithian/Spathian boundary interval is clearly a global event
Detrital Zircon U-Pb Geochronology of Upper Devonian and Lower Carboniferous Strata of Western Laurentia (North America): A Record of Transition from Passive to Convergent Margin
AbstractThe Late Devonian-Early Carboniferous (DC) Antler orogeny in southwestern Laurentia is contemporaneous with influx of clastic sediments, unconformities, and volcanism across much of western Laurentia (WL), suggesting the demise of the Paleozoic passive margin. However beyond the type Antler orogeny in southwestern Laurentia, the DC tectonic setting is still unclear. Westerly sediment provenance has been suggested as evidence of a convergent margin setting in a foreland basin. However, there is a gap in our understanding in central WL (Alberta and Montana) despite the fact that paleogeographic reconstructions place this area at the centre of WL. We provide detrital zircon (DZ) U-Pb geochronological data from strata in Alberta, Montana, and Nevada that are synchronous with the Antler orogeny to constrain sediment dispersal patterns and test the westerly sediment sourcing hypothesis. We show three DZ facies specific to particular geographic locations: DZ facies 1 in southern Nevada has a prominent subpopulation of early to mid-Mesoproterozoic (mode at 1430 Ma), DZ facies 2 in northeastern Nevada has a late Paleoproterozoic population (mode at 1823 Ma), and DZ facies 3 in Alberta and Montana displays Mesoproterozoic to Neoproterozoic (mode at 1036 Ma), mid-Paleozoic (mode at 411 Ma), and depositional (ca. 360-340 Ma) ages. North-south variation in DZ facies indicates that WL basins were locally sourced from various tectonic fragments having different signatures. Comparing our data with published data, we show that WL is dominated by DZ recycled from uplifted older strata with input from mid-Paleozoic arc terrane (s) to the west. Westerly sourcing is evidenced by the presence of near-depositional ages and affinities of this study’s DZ facies with strata located to the west. Our results and geological evidence from other studies suggest that the Antler orogeny triggered a depositional shift and controlled sediments dispersal in WL, signaling the demise of the Paleozoic passive margin
Pluto Integrated Camera-Spectrometer (PICS): A Low Mass, Low Power Instrument for Planetary Exploration
The concept we describe is an integrated instrument (a Pluto Integrated Camera Spectrometer, PICS) that will perform the functions of all three optical instruments required by the Pluto Fast Flyby Mission: the near-IR spectrometer, the camera, and the UV spectrometer. This integrated approach minimizes mass and power use. It also forced us early in the conceptual design to consider integrated observational sequences and integrated power management, thus ensuring compatible duty cycles (i.e. exposure times, readout rates) to meet the composite requirements for data collection, compression, and storage. Based on flight mission experience we believe that this integrated approach will result in substantial cost savings, both in reworking instrument designs during accommodation, as well as in sequence planning and integration. Finally, this integrated payload automatically yields a cohesive mission data set, optimized for correlative analysis. In our baseline concept, a single set of lightweight, multi-wavelength foreoptics is shared by an UV imaging spectrometer (160 spectral channels 10-150 nm), a two-CCD visible imaging system (simultaneously shuttered in two colors 300-500 nm and 500-1000 nm), and a near-IR imaging spectrometer (256 spectral channels 1300-2600 nm), The entire structure and optics is built from SiC, and includes an integrated radiator for thermal control. The design has no moving parts and each spectrometer covers a single octave in wavelength. For the Pluto mission, a separate port (aligned in a direction compatible with the radio occultation experiment) is provided for PICS measurement of a UV solar occultation and for spectral radiance calibration of the IR and visible subsystems. The integrated science this instrument will yield meets or exceeds all of the Priority-1A science objectives and captures many Priority-1B science objectives as well. The presentation will provide details of the PICS instrument design and describe the fabrication and testing of the integrated SiC structure and optics at SSG Inc. Final integration and test plans for the prototype will also be described
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