Crustal structure measurements near FRAM II in the pole abyssal plain

Duckworth, Gregory L.; Baggeroer, Arthur B.; Jackson, H. R.

doi:10.1016/0040-1951(82)90038-5

Cited by 26 publications

(15 citation statements)

References 23 publications

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“…Other investigations (Fig. 1a, lines a, d and f) yield a crustal thickness of 6-7 km (Kristoffersen et al 1982;Duckworth et al 1982). These results are too sparse in geographical distribution for any systematic match with global models to be perceived.…”

Section: Introductionmentioning

confidence: 70%

“…1a, lines a, d and f) yield a crustal thickness of 6–7 km (Kristoffersen et al. 1982; Duckworth et al . 1982).…”

Section: Introductionmentioning

confidence: 99%

“…Various seismic, magnetic, bathymetric and gravimetric experiments were carried out from drifting ice floes as the ARLIS II project (Kutschale 1966) or the FRAM I-IV expeditions (e.g. Duckworth et al 1982;Jackson et al 1982;Kristoffersen et al 1982). Some of the seismic refraction measurements ( Fig.…”

Section: Introductionmentioning

confidence: 99%

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Peculiarities of roughness and thickness of oceanic crust in the Eurasian Basin, Arctic Ocean

Weigelt

Jokat

2001

Geophysical Journal International

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Summary The Gakkel Ridge, northern boundary of the American and Eurasian plates, has the slowest spreading rate of the global ridge system. Therefore, it provides an excellent opportunity to study any dependence of crustal fabric on spreading rate. Two parameters, crustal surface roughness and crustal thickness, at the super‐slow‐spreading Gakkel Ridge (< 20 mm yr−1 full rate) are the subject of the following study. Seismic and gravity data acquired across the Gakkel Ridge and the adjacent Nansen and Amundsen basins during the ARCTIC'91 expedition are used. The surface of the basement, imaged along the seismic multichannel profiles, is very rough and varies in its topography from several hundreds of metres up to 1000 m. Its RMS‐roughness ranges from 450 m in the central Amundsen Basin to 584 m in the southern Eurasian Basin. These values agree reasonably well with RMS‐roughness values derived by an empirical model from spreading rates. The gravity models reveal a 5–6 km thick oceanic crust (density of 2900 kg m−3) in the central part of the Amundsen Basin, increasing to 9 km towards the Gakkel Ridge. At the southwestern end of the Eurasian Basin, the oceanic crust is only 2–5 km thick and thickens towards the Gakkel Ridge. In our model the ridge is composed of a 2 km thick upper layer with a density of 2600 kg m−3, underlain by an 8 km thick zone with a density of 2900 kg m−3. The increase of crustal thickness does not confirm theoretical models for the relation between spreading rate and crustal thickness. The results indicate that the super‐slow spreading rate of the Gakkel Ridge may have caused lateral variations in the crustal thickness of the Eurasian Basin.

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Section: Introductionmentioning

confidence: 70%

“…1a, lines a, d and f) yield a crustal thickness of 6–7 km (Kristoffersen et al. 1982; Duckworth et al . 1982).…”

Section: Introductionmentioning

confidence: 99%

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Peculiarities of roughness and thickness of oceanic crust in the Eurasian Basin, Arctic Ocean

Weigelt

Jokat

2001

Geophysical Journal International

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“…Melting models based on decompression melting of upwelling mantle [e.g., Reid and Jackson , 1981; Bown and White , 1994; Sparks and Parmentier , 1994] predict that melt production and crustal thickness decrease rapidly at spreading rates less than about 15 mm/yr as the result of conductive cooling of the uprising mantle. The few seismic studies that exist away from the “Yermak H‐Zone” to the west of 3°E have consistently shown thin 2–3 km crust [e.g., Duckworth et al , 1982; Jackson et al , 1982, 1990]. Quantitative modeling of bathymetry and gravity profiles across the Gakkel Ridge led Coakley and Cochran [1998] to conclude that if the average crustal density is less than 2900 kg/m 3 , than the average crustal thickness must be less than 4 km and probably no more than 1–2 km to satisfy the gravity data.…”

Section: Discussionmentioning

confidence: 99%

“…Seismic refraction measurements in the Eurasian Basin are limited to the western portion of the basin to the west of 20°E [ Jackson et al , 1990; Kristoffersen , 1990] and show a great range of crustal thickness. Measurements in some regions give a normal oceanic crustal thickness of 6–8 km, while other measurements suggest very thin 2–3 km thick crust [ Duckworth et al , 1982; Jackson et al , 1982]. Jackson et al [1982] argue that, on a set of refraction lines collected on the ice station FRAM I, thicker crust is associated with unusually high amplitude seafloor spreading magnetic anomalies and thin crust with areas of lower amplitude magnetic anomalies.…”

Section: Structure Of the Eurasian Basinmentioning

confidence: 99%

The Gakkel Ridge: Bathymetry, gravity anomalies, and crustal accretion at extremely slow spreading rates

et al. 2003

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[1] The Gakkel Ridge in the Arctic Ocean is the slowest spreading portion of the global mid-ocean ridge system. Total spreading rates range from 12.7 mm/yr near Greenland to 6.0 mm/yr where the ridge disappears beneath the Laptev Shelf. Swath bathymetry and gravity data for an 850 km long section of the Gakkel Ridge from 5°E to 97°E were obtained from the U.S. Navy submarine USS Hawkbill. The ridge axis is very deep, generally 4700-5300 m, within a well-developed rift valley. The topography is primarily tectonic in origin, characterized by linear rift-parallel ridges and fault-bounded troughs with up to 2 km of relief. Evidence of extrusive volcanic activity is limited and confined to specific locations. East of 32°E, isolated discrete volcanoes are observed at 25-95 km intervals along the axis. Abundant small-scale volcanism characteristic of the Mid-Atlantic Ridge (MAR) is absent. It appears that the amount of melt generated is insufficient to maintain a continuous magmatic spreading axis. Instead, melt is erupted on the seafloor at a set of distinct locations where multiple eruptions have built up central volcanoes and covered adjacent areas with low relief lava flows. Between 5°E and 32°E, almost no volcanic activity is observed except near 19°E. The ridge axis shoals rapidly by 1500 m over a 30 km wide area at 19°E, which coincides with a highstanding axis-perpendicular bathymetric high. Bathymetry and side scan data show the presence of numerous small volcanic features and flow fronts in the axial valley on the upper portions of the 19°E along-axis high. Gravity data imply up to 3 km of crustal thickening under the 19°E axis-perpendicular ridge. The 19°E magmatic center may result from interaction of the ridge with a passively imbedded mantle inhomogeneity. Away from 19°E, the crust appears thin and patchy and may consist of basalt directly over peridotite. The ridge axis is continuous with no transform offsets. However, sections of the ridge have distinctly different linear trends. Changes in ridge trend at 32°E and 63°E are associated with a set of bathymetric features that are very similar to each other and to inside/outside corner complexes observed at the MAR including highstanding ''inside corner'' ridges, which gravity data show to be of tectonic rather than magmatic origin.

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Physiography and Bathymetry of the Arctic Ocean seafloor

Weber¹

1989

The Arctic Seas

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Crustal structure measurements near FRAM II in the pole abyssal plain

Cited by 26 publications

References 23 publications

Peculiarities of roughness and thickness of oceanic crust in the Eurasian Basin, Arctic Ocean

Peculiarities of roughness and thickness of oceanic crust in the Eurasian Basin, Arctic Ocean

The Gakkel Ridge: Bathymetry, gravity anomalies, and crustal accretion at extremely slow spreading rates

Physiography and Bathymetry of the Arctic Ocean seafloor

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