Record of seamount production and off‐axis evolution in the western North Atlantic Ocean, 25°25′–27°10′N

Jaroslow, Gary E.; Smith, Deborah; Tucholke, Brian E.

doi:10.1029/1999jb900253

Cited by 13 publications

(4 citation statements)

References 44 publications

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“…Ridge show that our average density of 3.3 peaks of all sizes per 1000 km 2 is in the same order of magnitude as that obtained by Batiza et al (1989), but is an order of magnitude lower than that obtained by Smith & Cann (1990) and by Jaroslow et al (2000). The discrepancies observed in relation to the latter studies are probably due to the fact that they focused only on the immediate vicinity of the ridge, an area with exceptionally rugged topography (Smith & Cann 1990).…”

Section: Discussioncontrasting

confidence: 45%

Abundance and distribution of seamounts in the Azores

Morato

Machete²,

Kitchingman³

et al. 2008

Mar. Ecol. Prog. Ser.

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We characterized the seamount distribution of the economic exclusive zone (EEZ) of the Azores (Portugal) using 2 bathymetry datasets. Our algorithm showed that peaks and seamounts are common features in this region of the North Atlantic. The density obtained of 3.3 peaks of all sizes per 1000 km 2 is in the same order of magnitude as that obtained on the Mid-Atlantic Ridge by a few other studies. A total of 63 large and 398 small seamount-like features are mapped and described in the Azorean EEZ. Our distribution of seamounts predicts that about 57% of the potential Azores seamounts lie in the zone protected from MATERIALS AND METHODSIn the present study, seamounts are defined as any topographically distinct seafloor feature that is at least 200 m higher than the surrounding seafloor, but which does not break the sea surface. We classify seamounts as being large or small, depending on whether the height exceeds 1000 m (regardless of depth). This height separation is useful in isolating large seamounts, the global distribution of which is well resolved by satellite altimetry, from small seamounts, the distribution of which can only be derived from less encompassing local acoustic mapping.An automated methodology adapted from Kitchingman et al. (2007) was used to identify topographic structures with high probability of being seamounts. Two bathymetric datasets with different resolutions were used as the topographic bases.The MOMAR (monitoring the Mid-Atlantic Ridge) mesoscale bathymetric map (Lourenço et al. 1998; www.ipgp.jussieu.fr/rech/lgm/MOMAR/Data/Plateau _bathy.grd) was the finest scale bathymetrical grid available for the Azores region at the date of the analysis (February 2006) and was used for the area constrained by the parallels 36°and 41°N and the meridians 24°and 32°W. This dataset is supplied at a 1 min cell resolution, thus allowing a reasonable scale at which to perform an analysis for large seamountlike features. The 'global seafloor topography from satellite altimetry and ship depth soundings' database (Smith & Sandwell 1997; http://topex.ucsd.edu/sandwell/sandwell.html) at a 2 min cell resolution was used as the bathymetry dataset for the remaining area. The version used still contained some artefacts, such as a spurious deep trough in the NE region of the study area.The methodology followed 3 succeeding steps run on a cell-by-cell analysis over the bathymetric grids:(1) identifying all detectable peaks in the bathymetry dataset with the Environmental Systems Research Institute (ESRI) ArcGIS software flow direction and sink algorithms (www.esri.com), (2) isolating peaks with heights > 200 m above surrounding seafloor and displaying an approximately circular or elliptical shape and (3) isolating large seamount-like features (height >1000 m). The datasets produced after Step 1 will be called the 'peaks dataset', while the dataset produced after Step 3 will be used as the 'Azores seamount dataset'. The dataset produced after Step 2 minus that produced after Step 3 will be called the 's...

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Section: Discussioncontrasting

confidence: 45%

Abundance and distribution of seamounts in the Azores

Morato

Machete²,

Kitchingman³

et al. 2008

Mar. Ecol. Prog. Ser.

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“…They are large (-115 m average height, 1.5-2 km diameter), form a linear chain in the direction of plate spreading, and appear to survive intact following their formation on axis and subsequent uplift into the flanking crestal mountains and beyond (Figures lb and l c) [Rabain et al, 2001]. In contrast, typical MAR rift valley volcanoes are small (-60 m average height, <1 km diameter), isolated or piled on top of one another, and often destroyed or severely disrupted upon uplift from the inner valley [Smith and Cann, 1993;Bryan et al, 1994;Smith et al, 1999;Jaroslow et al, 2000]. Like many segments of the MAR [e.g., Brozena, 1986;Carbotte et al, 1991;Gente et al, 1992], the length of OH-1 has changed through time.…”

Section: Introductionmentioning

confidence: 99%

Crustal evolution over the last 2 m.y. at the Mid‐Atlantic Ridge OH‐1 segment, 35°N

Hosford¹,

Lin²,

Detrick³

2001

J. Geophys. Res.

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Abstract. We present the crustal and mantle velocity structure along the strike of the eastern rift mountains at 35øN on the Mid-Atlantic Ridge. These results were obtained by an inversion of -1800 Pg/Pn and-•450 PmP travel times and by gravity modeling. As commonly observed at slow spreading mid-ocean ridges, thicker crust (9 km) occurs at the segment midpoint, while thinner crust (7 km) is found toward the segment ends. This along strike variation occurs primarily in the lower crust, which is 7 km thick at the segment center and 4-6 km thick at the segment ends. In contrast, the thickness of the upper crust is relatively constant along strike. At the segment ends, relatively low velocities extend for 10-15 km along strike and from the seafloor to 4 km depth. These low velocities may indicate an attenuated melt supply and/or fracturing and alteration within the shallow to mid-crust. Directly beneath a cluster of three seamounts at the segment center is a region of relatively high velocity (+0.5 km/s) in the mid-crust. This feature may correspond to a frozen magma chamber that fed the overlying volcanoes. A synthesis of these results with those from two companion experiments along the rift valley and the conjugate flank provide a detailed record of crustal accretion and evolution at this segment. Specifically, the crustal velocity structures of each flank are nearly identical, and they exhibit a thinner and 16% faster upper crust than is observed on axis. The lower crust is remarkably similar in all three settings, except for a low-velocity body on axis, which is interpreted as a partially molten zone. The maximum crustal thickness is also similar in all three profiles, but north of the segment center, zero-age crust is nearly 4 km thinner than beneath the eastern flank and 2 km thinner than beneath the western flank. These differences may indicate that segment-centered mantle upwelling varies on a timescale of-2 m.y.

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“…Studies have shown that many of these new seamounts undergo extensive tectonic deformation by normal faulting that reduces their original heights considerably ( Jaroslow et al, 2000). It is also evident that the increased sediment coverage on older seafloor (e.g., Ludwig and Houtz, 1979) is likely to bury the smallest and most numerous seamounts with height less than 100 m after a few tens of millions of years.…”

Section: Seamount Provincesmentioning

confidence: 99%

Plate Tectonics

Wessel

2015

Treatise on Geophysics

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Record of seamount production and off‐axis evolution in the western North Atlantic Ocean, 25°25′–27°10′N

Cited by 13 publications

References 44 publications

Abundance and distribution of seamounts in the Azores

Abundance and distribution of seamounts in the Azores

Crustal evolution over the last 2 m.y. at the Mid‐Atlantic Ridge OH‐1 segment, 35°N

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