Iceland, the Farallon slab, and dynamic topography of the North Atlantic

Geology ◽  
2004 ◽  
Vol 32 (3) ◽  
pp. 177 ◽  
Author(s):  
Clinton P. Conrad ◽  
Carolina Lithgow-Bertelloni ◽  
Keith E. Louden
Keyword(s):  
North Atlantic ◽  
Dynamic Topography ◽  
The North ◽  
The North Atlantic

scholarly journals The deep Earth origin of the Iceland plume and its effects on regional surface uplift and subsidence

2016 ◽  
Author(s):  
N. Barnett-Moore ◽  
R. Hassan ◽  
N. Flament ◽  
R. D. Müller
Keyword(s):  
North Atlantic ◽  
Flow Model ◽  
Mantle Flow ◽  
Seismic Structure ◽  
Dynamic Topography ◽  
The North ◽  
Deep Mantle ◽  
Deep Earth ◽  
The North Atlantic ◽  
Iceland Plume

Abstract. The present-day seismic structure of the mantle under the North Atlantic indicates that the Iceland hotspot represents the surface expression of a deep mantle plume, which is thought to have erupted in the North Atlantic during the Paleocene. The spatial and temporal evolution of the plume since its eruption is still highly debated, and little is known about its deep mantle history. Here, a paleogeographically constrained global mantle flow model is used to investigate the evolution of deep Earth flow and surface dynamic topography in the North Atlantic since the Jurassic. The model shows that over the last ~ 100 Myr a remarkably stable pattern of convergent flow has prevailed in the lowermost mantle near the tip of the African Large Low-Shear Velocity Province (LLSVP), making it an ideal plume nucleation site. The present-day location of the model plume is ~ 10° southeast from the inferred present-day location of the Iceland plume. We apply a constant surface rotation to the model through time, derived from correcting for this offset at present-day. A comparison between the rotated model dynamic topography evolution and available offshore geological and geophysical observations across the region confirms that a widespread episode of Paleocene transient uplift followed by early Eocene anomalous subsidence can be explained by the mantle-driven effects of a plume head ~ 2000 km in diameter, arriving beneath central western Greenland during the Paleocene. The rotated model plume eruption location beneath Western Greenland is compatible with previous models. The mantle flow model underestimates the magnitude of observed anomalous subsidence during the Paleocene in some parts of the North Atlantic by as much as several hundred meters, which we attribute to upper mantle convection processes, not captured by the model.

scholarly journals Comparing the steric height in the Northern Atlantic with satellite altimetry

Ocean Science ◽  
2007 ◽  
Vol 3 (4) ◽  
pp. 485-490 ◽  
Author(s):  
V. O. Ivchenko ◽  
S. D. Danilov ◽  
D. V. Sidorenko ◽  
J. Schröter ◽  
M. Wenzel ◽  
...  
Keyword(s):  
North Atlantic ◽  
Satellite Altimetry ◽  
Sea Surface ◽  
Dynamic Topography ◽  
Dynamic Height ◽  
Steric Height ◽  
The North ◽  
Northern Atlantic ◽  
The North Atlantic ◽  
Surface Dynamic

Abstract. Anomalies of dynamic height derived from an analysis of Argo profiling buoys data are analysed to assess the relative roles of contributions from temperature and salinity over the North Atlantic for the period of 1999–2004. They are compared with dynamic topography anomalies based on TOPEX/Poseidon and Jason altimetry. It is shown that the halosteric contribution to the anomalies of dynamic height is comparable in magnitude to the thermosteric one over the period analyzed. Taking both salinity and temperature into account improves the agreement between zonally averaged trends in the satellite dynamic topography and dynamic height increasing the correlation between them to 0.73 from 0.63 when only temperature variability is taken into account. The implication of this result is that the salinity contribution cannot be neglected in the North Atlantic and that one cannot rely on estimating the thermosteric part by anomalies in the sea surface dynamic topography derived from the satellite altimetry.

scholarly journals Combining T/P altimetric data with hydrographic data to estimate the mean dynamic topography of the North Atlantic and improve the geoid

1998 ◽  
Vol 16 (5) ◽  
pp. 638-650 ◽  
Author(s):  
P. LeGrand ◽  
H. Mercier ◽  
T. Reynaud
Keyword(s):  
North Atlantic ◽  
General Circulation ◽  
Geoid Height ◽  
Dynamic Topography ◽  
Hydrographic Data ◽  
Mean Dynamic Topography ◽  
The North ◽  
Altimetric Data ◽  
The Mean ◽  
The North Atlantic

Abstract. The mean dynamic topography of the surface of the North Atlantic is estimated using an inverse model of the ocean circulation constrained by hydrographic and altimetric observations. In the North Atlantic, altimetric observations have no significant impact on the topography estimate because of the limited precision of available geoid height models. They have a significant impact, however, when uncertainties in the density field are increased to simulate interpolation errors in regions where hydrographic data are scarce. This result, which moderates the conclusion drawn by Ganachaud and co-workers of no significant contribution of altimetric observations to the determination of the large-scale steady circulation, reflects the simple idea that altimetric data are most useful near the surface of the ocean and in areas where the hydrography is poorly determined. One application of the present inverse estimate of the mean dynamic topography is to compute a geoid height correction over the North Atlantic which reduces the uncertainty in the geoid height expanded to spherical harmonic 40 down to a level of about 5 cm.Key words. Oceanography: general (climate and interannual variability) · Oceanography: physical (general circulation; remote sensing)

scholarly journals Comparing the steric height in the Northern Atlantic with satellite altimetry

2007 ◽  
Vol 4 (3) ◽  
pp. 441-457 ◽  
Author(s):  
V. O. Ivchenko ◽  
S. D. Danilov ◽  
D. V. Sidorenko ◽  
J. Schroeter ◽  
M. Wenzel ◽  
...  
Keyword(s):  
North Atlantic ◽  
Satellite Altimetry ◽  
Sea Surface ◽  
Dynamic Topography ◽  
Dynamic Height ◽  
Steric Height ◽  
The North ◽  
Northern Atlantic ◽  
The North Atlantic ◽  
Surface Dynamic

Abstract. Anomalies of dynamic height derived from an analysis of Argo profiling buoys data are analysed to assess the relative roles of contributions from temperature and salinity over the North Atlantic for the period of 1999–2004. They are compared with dynamic topography anomalies based on TOPEX/Poseidon and Jason altimetry. It is shown that the halosteric contribution to the anomalies of dynamic height is comparable in magnitude to the thermosteric one over the period analyzed. Taking both salinity and temperature into account improves the agreement between zonally averaged trends in the satellite dynamic topography and dynamic height increasing the correlation between them to 0.73 from 0.63 when only temperature variability is taken into account. The implication of this result is that the salinity contribution cannot be neglected in the North Atlantic and that one cannot rely on estimating the thermosteric part by anomalies in the sea surface dynamic topography derived from the satellite altimetry.

scholarly journals The deep Earth origin of the Iceland plume and its effects on regional surface uplift and subsidence

Solid Earth ◽  
2017 ◽  
Vol 8 (1) ◽  
pp. 235-254 ◽  
Author(s):  
Nicholas Barnett-Moore ◽  
Rakib Hassan ◽  
Nicolas Flament ◽  
Dietmar Müller
Keyword(s):  
North Atlantic ◽  
North Atlantic Ocean ◽  
Nucleation Site ◽  
Mantle Flow ◽  
Seismic Structure ◽  
Dynamic Topography ◽  
The North ◽  
Deep Mantle ◽  
Deep Earth ◽  
The North Atlantic

Abstract. The present-day seismic structure of the mantle under the North Atlantic Ocean indicates that the Iceland hotspot represents the surface expression of a deep mantle plume, which is thought to have erupted in the North Atlantic domain during the Palaeocene. The spatial and temporal evolution of the plume since its eruption is still highly debated, and little is known about its deep mantle history. Here, we use palaeogeographically constrained global mantle flow models to investigate the evolution of deep Earth flow beneath the North Atlantic since the Jurassic. The models show that over the last ∼ 100 Myr a remarkably stable pattern of convergent flow has prevailed in the lowermost mantle near the tip of the African Large Low-Shear Velocity Province (LLSVP), making it an ideal plume nucleation site. We extract model dynamic topography representative of a plume beneath the North Atlantic region since eruption at ∼ 60 Ma to present day and compare its evolution to available offshore geological and geophysical observations across the region. This comparison confirms that a widespread episode of Palaeocene transient uplift followed by early Eocene anomalous subsidence can be explained by the mantle-driven effects of a plume head ∼ 2500 km in diameter, arriving beneath central eastern Greenland during the Palaeocene. The location of the model plume eruption beneath eastern Greenland is compatible with several previous models. The predicted dynamic topography is within a few hundred metres of Palaeocene anomalous subsidence derived from well data. This is to be expected given the current limitations involved in modelling the evolution of Earth's mantle flow in 3-D, particularly its interactions with the base of a heterogeneous lithosphere as well as short-wavelength advective upper mantle flow, not captured in the presented global models.

The Currents of the North Atlantic

1892 ◽  
Vol 34 (872supp) ◽  
pp. 13940-13941
Author(s):  
Richard Beynon
Keyword(s):  
North Atlantic ◽  
The North ◽  
The North Atlantic

NATO adaptation to current challenges and mechanisms of Ukraine’s cooperation with the North Atlantic Treaty Organization

2019 ◽  
pp. 73-81
Author(s):  
Oleh Poshedin
Keyword(s):  
North Atlantic ◽  
Task Force ◽  
Response Force ◽  
Cyber Attack ◽  
Adaptation Measures ◽  
Joint Force ◽  
Security Environment ◽  
The North ◽  
The North Atlantic ◽  
Area Of Influence

The purpose of the article is to describe the changes NATO undergoing in response to the challenges of our time. Today NATO, as a key element of European and Euro-Atlantic security, is adapting to changes in the modern security environment by increasing its readiness and ability to respond to any threat. Adaptation measures include the components required to ensure that the Alliance can fully address the security challenges it might face. Responsiveness NATO Response Force enhanced by developing force packages that are able to move rapidly and respond to potential challenges and threats. As part of it, was established a Very High Readiness Joint Task Force, a new Allied joint force that deploy within a few days to respond to challenges that arise, particularly at the periphery of NATO’s territory. NATO emphasizes, that cyber defence is part of NATO’s core task of collective defence. A decision as to when a cyber attack would lead to the invocation of Article 5 would be taken by the North Atlantic Council on a case-by-case basis. Cooperation with NATO already contributes to the implementation of national security and defense in state policy. At the same time, taking into account that all decision-making in NATO based on consensus, Ukraine’s membership in the Alliance quite vague perspective. In such circumstances, in Ukraine you often can hear the idea of announcement of a neutral status. It is worth reminding that non-aligned status did not save Ukraine from Russian aggression. Neutral status will not accomplish it either. All talks about neutrality and the impossibility of Ukraine joining NATO are nothing but manipulations, as well as recognition of the Ukrainian territory as Russian Federation area of influence (this country seeks to sabotage the Euro-Atlantic movement of Ukraine). Think about it, Moldova’s Neutrality is enshrined in the country’s Constitution since 1994. However, this did not help Moldova to restore its territorial integrity and to force Russia to withdraw its troops and armaments from Transnistria.

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