| |
Records |
Links |
|
Author |
Spracklen, D.V.; Arnold, S.R.; Sciare, J.; Carslaw, K.S.; Pio, C. |
|
| |
Title |
Globally significant oceanic source of organic carbon aerosol |
Type |
Journal Article |
| |
Year |
2008 |
Publication |
Geophysical research letters |
Abbreviated Journal |
|
|
| |
Volume |
35 |
Issue |
|
Pages |
|
|
| |
Keywords |
organic carbon; ocean; aerosol; 0305 Atmospheric Composition and Structure: Aerosols and particles; 0315 Atmospheric Composition and Structure: Biosphere/atmosphere interactions; 0312 Atmospheric Composition and Structure: Air/sea constituent fluxes |
|
| |
Abstract |
Significant concentrations of organic carbon (OC) aerosol are observed at three oceanic surface sites (Amsterdam Island, Azores and Mace Head). Two global chemical transport models (CTMs) underpredict OC concentrations at these sites (normalised mean bias of ?67% and ?58%). During periods of high biological activity monthly mean concentrations are underpredicted by a factor of 5–20. At Amsterdam Island and Mace Head, observed OC correlates well (R2 = 0.61–0.77) with back-trajectory weighted chlorophyll-a, suggesting an oceanic OC source driven by biological activity. We use a combination of remote sensed chlorophyll-a, back trajectories and observed OC to derive an empirical relation between chlorophyll-a and the total oceanic OC emission flux. Using the GEOS-chem CTM we show a global oceanic OC emission, from primary and secondary sources, of ?8 Tg/year matches observations. This emission is comparable in magnitude to the fossil fuel OC source and increases the simulated global OC burden by 20%. |
|
| |
Programme |
414;415 |
|
| |
Campaign |
|
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
Bachelor's thesis |
|
| |
Publisher  |
American Geophysical Union |
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0094-8276 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
|
Approved |
yes |
|
| |
Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5523 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Francia, P.; Lanzerotti, L.J.; Villante, U.; Lepidi, S.; Di Memmo, D. |
|
| |
Title |
A statistical analysis of low-frequency magnetic pulsations at cusp and cap latitudes in Antarctica |
Type |
Journal Article |
| |
Year |
2005 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
|
| |
Volume |
110 |
Issue |
|
Pages |
|
|
| |
Keywords |
polar cap and cusp pulsations; magnetospheric wave guide modes; field line resonances; open/closed field line boundary; 2784 Magnetospheric Physics: Solar wind/magnetosphere interactions; 2740 Magnetospheric Physics: Magnetospheric configuration and dynamics; 2776 Magnetospheric Physics: Polar cap phenomena; 2706 Magnetospheric Physics: Cusp; 2752 Magnetospheric Physics: MHD waves and instabilities |
|
| |
Abstract |
We report a statistical analysis of low-frequency magnetic variations (magnetic pulsations, 0.8–7 mHz) at South Pole (74°S corrected geomagnetic latitude) and Terra Nova Bay (80°S) during 1996. The results show that at South Pole (at cusp latitudes) the pulsation power exhibits two maxima during the day, one in the local premidnight and the other in the morning. The first maximum disappears when the analysis is restricted to northward interplanetary magnetic field conditions (B z > 1 nT), suggesting that it might be associated to substorm phenomena. During closed magnetospheric conditions, when the cusp is expected to be located poleward with respect to the station, the spectral and polarization characteristics of pulsations between 1 and 3 mHz suggest that resonant oscillations of the outermost closed field lines commonly occur at South Pole in the local morning. At Terra Nova Bay, in the polar cap, the pulsation power is much lower and its diurnal variation is characterized by a single maximum, which occurs around local noon, when the station approaches the cusp. The corresponding polarization pattern indicates that Terra Nova Bay is always located poleward with respect to resonant field lines. |
|
| |
Programme |
1130 |
|
| |
Campaign |
|
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
American Geophysical Union |
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0148-0227 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
|
Approved |
yes |
|
| |
Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5495 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Ciais, P.; Manning, A.C.; Reichstein, M.; Zaehle, S.; Bopp, L. |
|
| |
Title |
Nitrification amplifies the decreasing trends of atmospheric oxygen and implies a larger land carbon uptake |
Type |
Journal Article |
| |
Year |
2007 |
Publication |
Global biogeochemical cycles |
Abbreviated Journal |
|
|
| |
Volume |
21 |
Issue |
|
Pages |
|
|
| |
Keywords |
carbon cycle; nitrogen cycle; oxygen; 0330 Atmospheric Composition and Structure: Geochemical cycles |
|
| |
Abstract |
Atmospheric O2 trend measurements are used to partition global oceanic and land biotic carbon sinks on a multiannual basis. The underlying principle is that a terrestrial uptake or release of CO2 is accompanied by an opposite flux of O2. The molar ratio of the CO2 and O2 terrestrial fluxes should be 1, if no other elements are considered. However, reactive nitrogen produced by human activities (e.g., fertilizers, N deposition) is also being incorporated into plant tissues. The various reaction pathways of the terrestrial nitrogen cycle cause fluxes of atmospheric O2. Thus the cycles of nitrogen, carbon, and oxygen must be linked together. We report here on previously unconsidered anthropogenic nitrogen-related mechanisms which impact atmospheric O2 trends and thus the derived global carbon sinks. In particular, we speculate that anthropogenic-driven changes are driving the global nitrogen cycle to a more oxidized state, primarily through nitrification, nitrate fertilizer industrial production, and combustion of fossil fuels and anthropogenic biomass burning. The sum of these nitrogen-related processes acts to additionally decrease atmospheric O2 and slightly increase atmospheric CO2. We have calculated that the effective land biotic O2:CO2 molar ratio ranges between 0.76 and 1.04 rather than 1.10 (moles of O2 produced per mole of CO2 consumed) over the period 1993–2003, depending on which of four contrasting nitrogen oxidation and reduction pathway scenarios is used. Using the scenario in which we have most confidence, this implies a 0.23 PgC yr?1 correction to the global land biotic and oceanic carbon sinks of most recently reported estimates over 1993–2003, with the land biotic sink becoming larger and the oceanic sink smaller. We have attributed large uncertainties of 100% to all nitrogen-related O2 and CO2 fluxes and this corresponds up to ±0.09 PgC yr?1 increase in global carbon sink uncertainties. Thus accounting for anthropogenic nitrogen-related terrestrial fluxes of O2 results in a 45% larger land biotic sink of 0.74 ± 0.78 PgC yr?1 and a slightly smaller oceanic sink of 2.01 ± 0.66 PgC yr?1 for the decade 1993–2003. |
|
| |
Programme |
439 |
|
| |
Campaign |
|
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
American Geophysical Union |
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0886-6236 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
|
Approved |
yes |
|
| |
Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5515 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Chulliat, A.; Blanter, E.; Le Mouël, J.-L.; Shnirman, M. |
|
| |
Title |
On the seasonal asymmetry of the diurnal and semidiurnal geomagnetic variations |
Type |
Journal Article |
| |
Year |
2005 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
|
| |
Volume |
110 |
Issue |
|
Pages |
|
|
| |
Keywords |
daily variation; lower thermospheric winds; ionospheric dynamo; current system; geomagnetic activity; equinoxes; 1555 Geomagnetism and Paleomagnetism: Time variations: diurnal to decadal; 2437 Ionosphere: Ionospheric dynamics; 3369 Atmospheric Processes: Thermospheric dynamics; 3389 Atmospheric Processes: Tides and planetary waves |
|
| |
Abstract |
The diurnal and semidiurnal variations of the geomagnetic field are investigated at 18 observatories using long series of hourly values (up to 97 years at Sitka). The seasonal variations of amplitude of the 12-hour and 24-hour lines are obtained for the H and Z components using a 28-day sliding window. The Fourier analysis is performed using either all days within the window or only the five quietest days. At midlatitudes a strong lack of symmetry about the summer solstice is observed for both lines and both components. This effect is enhanced when selecting quiet days. When averaged over the entire series, the sign of this seasonal asymmetry is the same at 9 out of 10 midlatitude observatories for both lines and for a given component; it is opposite for the H and Z components. Such a coherent seasonal asymmetry is not found at low and high latitudes. At high latitudes a strong annual variation is found inside the polar caps, while a strong semiannual variation is found in the auroral zones. When selecting quiet days, these two effects are weaker, and the seasonal asymmetry becomes comparable to that at midlatitudes. At all latitudes the year-to-year variations of the seasonal asymmetry are uncorrelated with solar activity. It is suggested that lower thermospheric winds may have a similar seasonal asymmetry between spring and autumn equinoxes. Such an asymmetry is present in the published literature but has been overlooked. Possible causes for this wind asymmetry are reviewed. |
|
| |
Programme |
139 |
|
| |
Campaign |
|
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
American Geophysical Union |
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0148-0227 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
|
Approved |
yes |
|
| |
Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5485 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Courtillot, V.; Le Mouël, J.-L. |
|
| |
Title |
The study of Earth's magnetism (1269–1950): A foundation by Peregrinus and subsequent development of geomagnetism and paleomagnetism |
Type |
Journal Article |
| |
Year |
2007 |
Publication |
Reviews of geophysics |
Abbreviated Journal |
|
|
| |
Volume |
45 |
Issue |
|
Pages |
|
|
| |
Keywords |
history; geomagnetism; paleomagnetism; 1599 Geomagnetism and Paleomagnetism: General or miscellaneous; 1714 History of Geophysics: Geomagnetism and paleomagnetism; 5440 Planetary Sciences: Solid Surface Planets: Magnetic fields and magnetism; 7999 Space Weather: General or miscellaneous; 9820 General or Miscellaneous: Techniques applicable in three or more fields |
|
| |
Abstract |
This paper summarizes the histories of geomagnetism and paleomagnetism (1269–1950). The role of Peregrinus is emphasized. In the sixteenth century a debate on local versus global departures of the field from that of an axial dipole pitted Gilbert against Le Nautonier. Regular measurements were undertaken in the seventeenth century. At the turn of the nineteenth century, de Lamanon, de Rossel, and von Humboldt discovered the decrease of intensity as one approaches the equator. Around 1850, three figures of rock magnetism were Fournet (remanent and induced magnetizations), Delesse (remagnetization in a direction opposite to the original), and Melloni (direction of lava magnetization acquired at time of cooling). Around 1900, Brunhes discovered magnetic reversals. In the 1920s, Chevallier produced the first magnetostratigraphy and hypothesized that poles had undergone enormous displacements. Matuyama showed that the Earth's field had reversed before the Pleistocene. Our review ends in the 1940s, when exponential development of geomagnetism and paleomagnetism starts. |
|
| |
Programme |
139 |
|
| |
Campaign |
|
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
American Geophysical Union |
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
8755-1209 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
|
Approved |
yes |
|
| |
Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5486 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Flückiger, J.; Monnin, E.; Stauffer, B.; Schwander, J.; Stocker, T.F.; Chappellaz, J.; Raynaud, D.; Barnola, J.-M. |
|
| |
Title |
High-resolution Holocene N2O ice core record and its relationship with CH4 and CO2 |
Type |
Journal Article |
| |
Year |
2002 |
Publication |
Global biogeochemical cycles |
Abbreviated Journal |
|
|
| |
Volume |
16 |
Issue |
|
Pages |
|
|
| |
Keywords |
0325 Atmospheric Composition and Structure: Evolution of the atmosphere; 0365 Atmospheric Composition and Structure: Troposphere—composition and chemistry; 1610 Global Change: Atmosphere; 3344 Meteorology and Atmospheric Dynamics: Paleoclimatology |
|
| |
Abstract |
Nitrous oxide (N2O) concentration records exist for the last 1000 years and for time periods of rapid climatic changes like the transition from the last glacial to today's interglacial and for one of the fast climate variations during the last ice age. Little is known, however, about possible N2O variations during the more stable climate of the present interglacial (Holocene) spanning the last 11 thousand years. Here we fill this gap with a high-resolution N2O record measured along the European Project for Ice Coring in Antarctica (EPICA) Dome C Antarctic ice core. On the same ice we obtained high-resolution methane and carbon dioxide records. This provides the unique opportunity to compare variations of the three most important greenhouse gases (after water vapor) without any uncertainty in their relative timing. The CO2 and CH4 records are in good agreement with previous measurements on other ice cores. The N2O concentration started to decrease in the early Holocene and reached minimum values around 8 ka (<260 ppbv) before a slow increase to its preindustrial concentration of ?265 ppbv. |
|
| |
Programme |
960 |
|
| |
Campaign |
|
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
American Geophysical Union |
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0886-6236 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
|
Approved |
yes |
|
| |
Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5545 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Eisen, O.; Frezzotti, M.; Genthon, C.; Isaksson, E.; Magand, O.; van den Broeke, M.R.; Dixon, D.A.; Ekaykin, A.; Holmlund, P.; Kameda, T.; Karlöf, L.; Kaspari, S.; Lipenkov, V.Y.; Oerter, H.; Takahashi, S.; Vaughan, D.G. |
|
| |
Title |
Ground-based measurements of spatial and temporal variability of snow accumulation in East Antarctica |
Type |
Journal Article |
| |
Year |
2008 |
Publication |
Reviews of geophysics |
Abbreviated Journal |
|
|
| |
Volume |
46 |
Issue |
|
Pages |
|
|
| |
Keywords |
surface mass balance; East Antarctica; measurements; ground-truthing; 0762 Cryosphere: Mass balance; 0726 Cryosphere: Ice sheets; 0794 Cryosphere: Instruments and techniques; 9310 Geographic Location: Antarctica; 1621 Global Change: Cryospheric change |
|
| |
Abstract |
The East Antarctic Ice Sheet is the largest, highest, coldest, driest, and windiest ice sheet on Earth. Understanding of the surface mass balance (SMB) of Antarctica is necessary to determine the present state of the ice sheet, to make predictions of its potential contribution to sea level rise, and to determine its past history for paleoclimatic reconstructions. However, SMB values are poorly known because of logistic constraints in extreme polar environments, and they represent one of the biggest challenges of Antarctic science. Snow accumulation is the most important parameter for the SMB of ice sheets. SMB varies on a number of scales, from small-scale features (sastrugi) to ice-sheet-scale SMB patterns determined mainly by temperature, elevation, distance from the coast, and wind-driven processes. In situ measurements of SMB are performed at single points by stakes, ultrasonic sounders, snow pits, and firn and ice cores and laterally by continuous measurements using ground-penetrating radar. SMB for large regions can only be achieved practically by using remote sensing and/or numerical climate modeling. However, these techniques rely on ground truthing to improve the resolution and accuracy. The separation of spatial and temporal variations of SMB in transient regimes is necessary for accurate interpretation of ice core records. In this review we provide an overview of the various measurement techniques, related difficulties, and limitations of data interpretation; describe spatial characteristics of East Antarctic SMB and issues related to the spatial and temporal representativity of measurements; and provide recommendations on how to perform in situ measurements. |
|
| |
Programme |
411;454 |
|
| |
Campaign |
|
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
American Geophysical Union |
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
8755-1209 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
|
Approved |
yes |
|
| |
Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5492 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Garcia, S.; Angelier, J.; Bergerat, F.; Homberg, C.; Dauteuil, O. |
|
| |
Title |
Influence of rift jump and excess loading on the structural evolution of northern Iceland |
Type |
Journal Article |
| |
Year |
2008 |
Publication |
Tectonics |
Abbreviated Journal |
|
|
| |
Volume |
27 |
Issue |
|
Pages |
|
|
| |
Keywords |
rift jump; structural evolution; lava dip; dyke; fault; flexure zone; Iceland; 8010 Structural Geology: Fractures and faults; 8036 Structural Geology: Paleoseismology; 8178 Tectonophysics: Tectonics and magmatism; 8137 Tectonophysics: Hotspots, large igneous provinces, and flood basalt volcanism; 9325 Geographic Location: Atlantic Ocean |
|
| |
Abstract |
New structural data combined with published structural and geochronological data allow reconstruction of the structural evolution that followed the last rift jump across northern Iceland. Tertiary lava flows erupted along the Skagafjördur paleo-rift have been down-bent under the weight of, and in the direction of, Plio-Pleistocene lava flows emitted from the Northern Volcanic Zone and the central part of Iceland. This down-bending process involved development of local flexure zones and a flexural extension along the resulting monoclines. This structural reorganization explains the existence of the Húnaflói-Skagi synform without need for a paleo-rift axis along it, in agreement with previous radiometric dating. The large amount of Plio-Pleistocene lava flows erupted in Central Iceland may have been enhanced by ice cap loading. |
|
| |
Programme |
316 |
|
| |
Campaign |
|
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
American Geophysical Union |
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0278-7407 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
|
Approved |
yes |
|
| |
Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5497 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Magand, O.; Genthon, C.; Fily, M.; Krinner, G.; Picard, G.; Frezzotti, M.; Ekaykin, A.A. |
|
| |
Title |
An up-to-date quality-controlled surface mass balance data set for the 90°–180°E Antarctica sector and 1950–2005 period |
Type |
Journal Article |
| |
Year |
2007 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
|
| |
Volume |
112 |
Issue |
|
Pages |
|
|
| |
Keywords |
surface mass balance; East Antarctica; data quality; 0762 Cryosphere: Mass balance; 9310 Geographic Location: Antarctica; 0736 Cryosphere: Snow; 0776 Cryosphere: Glaciology; 0794 Cryosphere: Instruments and techniques |
|
| |
Abstract |
On the basis of thousands of surface mass balance (SMB) field measurements over the entire Antarctic ice sheet it is currently estimated that more than 2 Gt of ice accumulate each year at the surface of Antarctica. However, these estimates suffer from large uncertainties. Various problems affect Antarctic SMB measurements, in particular, limited or unwarranted spatial and temporal representativeness, measurement inaccuracy, and lack of quality control. We define quality criteria on the basis of (1) an up-to-date review and quality rating of the various SMB measurement methods and (2) essential information (location, dates of measurements, time period covered by the SMB values, and primary data sources) related to each SMB data. We apply these criteria to available SMB values from Queen Mary to Victoria lands (90°–180°E Antarctic sector) from the early 1950s to present. This results in a new set of observed SMB values for the 1950–2005 time period with strong reduction in density and coverage but also expectedly reduced inaccuracies and uncertainties compared to other compilations. The quality-controlled SMB data set also contains new results from recent field campaigns (International Trans-Antarctic Scientific Expedition (ITASE), Russian Antarctic Expedition (RAE), and Australian National Antarctic Research Expeditions (ANARE) projects) which comply with the defined quality criteria. A comparative evaluation of climate model results against the quality-controlled updated SMB data set and other widely used ones illustrates that such Antarctic SMB studies are significantly affected by the quality of field SMB values used as reference. |
|
| |
Programme |
411;454 |
|
| |
Campaign |
|
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
American Geophysical Union |
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0148-0227 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
|
Approved |
yes |
|
| |
Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5502 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Montagner, J.-P.; Marty, B.; Stutzmann, E.; Sicilia, D.; Cara, M.; Pik, R.; Lévêque, J.-J.; Roult, G.; Beucler, E.; Debayle, E. |
|
| |
Title |
Mantle upwellings and convective instabilities revealed by seismic tomography and helium isotope geochemistry beneath eastern Africa |
Type |
Journal Article |
| |
Year |
2007 |
Publication |
Geophysical research letters |
Abbreviated Journal |
|
|
| |
Volume |
34 |
Issue |
|
Pages |
|
|
| |
Keywords |
anisotropy tomography; helium isotope data; Africa; 8121 Tectonophysics: Dynamics: convection currents, and mantle plumes; 7270 Seismology: Tomography; 1040 Geochemistry: Radiogenic isotope geochemistry; 7208 Seismology: Mantle; 9305 Geographic Location: Africa |
|
| |
Abstract |
The relationship between intraplate volcanism and continental tectonics has been investigated for North and East Africa using a high resolution three-dimensional anisotropic tomographic model derived from seismic data of a French experiment “Horn of Africa” and existing broadband data. The joint inversion for seismic velocity and anisotropy of the upper 400 km of the mantle, and geochemical data reveals a complex interaction between mantle upwellings, and lithosphere. Two kinds of mantle upwellings can be distinguished: The first one, the Afar “plume” originates from deeper than 400 km and is characterized by enrichment in primordial 3He and 3He/4He ratios higher than those along mid-ocean ridges (MOR). The second one, associated with other Cenozoic volcanic provinces (Darfur, Tibesti, Hoggar, Cameroon), with 3He/4He ratios similar to, or lower than MOR, is a consequence of shallower upwelling. The presumed asthenospheric convective instabilities are oriented in an east-west direction, resulting from interaction between south-north asthenospheric mantle flow, main plume head and topography on the base of lithosphere. |
|
| |
Programme |
133;906 |
|
| |
Campaign |
|
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
American Geophysical Union |
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0094-8276 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
|
Approved |
yes |
|
| |
Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5511 |
|
| Permanent link to this record |
