On the thermal evolution of passive continental margins, thermal depth anomalies, and the Norwegian‐Greenland Sea

Zielinski, Gary W.

doi:10.1029/jb084ib13p07577

Cited by 18 publications

(14 citation statements)

References 34 publications

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“…Because of very long distances to well calibration data, and because the structural evolution of this area differs considerably from that of the better-explored Haltenbanken and North Sea, the temperature-depth relationships in the Vøring Basin have been uncertain. Previous heat-flow data from the area include gravity spear data reported by Haenel (1974), Langseth & Zielinski (1974), Zielinski (1977Zielinski ( , 1979, Sundvor et al (1989), and a single heat-flow value reported from ODP hole 644 (Eldholm et al 1987, p. 650). Most of these have been discussed more recently by Vogt & Sundvor (1996) and Sundvor et al (2000).…”

Section: Introductionmentioning

confidence: 94%

Heat flow in the Vøring Basin, Mid-Norwegian Shelf

Ritter

Zielinski²,

Weiss

et al. 2004

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In situ temperature and heat flow were determined in 1994 at 159 sites, grouped into 66 clusters between latitude 65 N and 67 30' N at water depths from 669 m to 1464 m. The mean of all cluster heat-flow measurements conducted in this survey was 58.5 mW m 2 , with a standard error of 4.40 mW m 2 . The mean heat flow from IKU well data for the Trøndelag Platform is 56.2 6.65 mW m 2 . Shorter wavelength heat-flow variations appear to be controlled structurally and can be explained by sedimentation and thermal refraction effects. High heat flow associated with faulted structural highs such as the Nyk High and Vema Dome-Rym Fault Zone may also result from hydrothermal convection. Relatively isolated high (106.6 mW m 2 ) heat flow observed at 846 m water depth may be an artefact of bottom water disturbances; however, virtually identical deep-water heat-flow anomalies, believed to be of hydrothermal origin, also exist. While heat-flow measurements made at water depths less than 1000 m should be regarded with caution, there is presently no justification for eliminating those exhibiting linear heat flow with depth. Submarine avalanches seem unimportant in the survey area. Neither crustal thinning, underplating nor sill intrusion, within the last 50 Ma, would have a measurable effect on present-day heat flow. The net effect of crustal thinning may be a reduction of the crustal heat generation potential, depending on the degree of thinning of the upper crust, since the accumulating sediments cannot compensate fully for the lost heat generation from a crystalline basement.

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Section: Introductionmentioning

confidence: 94%

Heat flow in the Vøring Basin, Mid-Norwegian Shelf

Ritter

Zielinski²,

Weiss

et al. 2004

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“…This leaves the mechanism for the steep elevation gradient at the outer flank of the plateau. A thermal origin is ruled out because Zielinski (1979) demonstrated that the heat flow distribution is consistent with an oceanic model with a continent/ocean boundary in the vicinity of the Wring Plateau Escarpment. We ascribe the gradient instead to isostatic compensation of the excess load of intrusives and ex-trusives emplaced during the early opening.…”

Section: Post-rift Evolution Subsidencementioning

confidence: 99%

“…15). We also have to account for the depth of the Mohns Ridge, which is 0.5-1.0 km shallower than the average world ocean (Cochran and Talwani, 1978;Zielinski, 1979), although the oceanic crust in the Lofoten Basin has subsided more rapidly than normal (Vestby, 1980).…”

Section: Post-rift Evolution Subsidencementioning

confidence: 99%

Evolution of the Vøring Volcanic Margin

Eldholm¹,

Thiede²,

Taylor³

1989

Proceedings of the Ocean Drilling Program

136

107

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ODP Sites 642 and 643 recovered a succession of rocks which have greatly improved the understanding of how the Cenozoic volcanic Wring Margin evolved, particularly by providing important constraints on the series of events that occurred during the initial opening of the Norwegian-Greenland Sea. The more than 900 m of igneous rocks and interbedded sediments drilled at Site 642 constitute two distinct, strikingly different volcanic series. The upper series, composed of transitional mid-oceanic tholeiitic lava flows and thin interbedded volcaniclastic sediments confirmed the seaward-dipping reflectors to be a terrestrially constructed extrusive complex. The lower series, probably extending for several hundred meters below the bottom of the hole, consists of another flow complex of dacitic composition, some dikes and thicker interbedded sediments, partially continentally derived. We suggest that the margin evolved by crustal extension in the Paleocene accompanied by uplift and a progressively more intense invasion of dikes and sills in the rift zone. Just prior to breakup, magma from shallow crustal melts produced the lower series. The upper series was constructed during an intense, rapidly waning, volcanic surge of subaerial accretion of oceanic magma following breakup in middle of Chron 24.2R. The surge is characterized by a much increased rate of magma production and high spreading rate. The upper series cover both newly formed oceanic crust and large areas of the adjacent thinned continental crust. The dipping wedge was formed by subsidence due to loading and thermal contraction, possibly amplified by a tectonic force. When the surge had abated, the injection center quickly subsided and normal oceanic crust was formed. Our interpretation is that the continent/ocean boundary occurs at the seaward termination of reflector K, which separates the two volcanic series. However, a region of strongly intruded transitional crust is inferred in 30-to 50-km wide zones on either side of the Vdring Plateau Escarpment.The Wring Margin experienced crustal uplift and extension prior to breakup, restricted to a Tertiary marginal basin west of the present shelf edge. The initial volcanic surge and shallow extrusion level are related to a higher than normal temperature at the base of the lithosphere, inducing partial melting combined with opening in previously thinned crust. The commonly described non-extensional nature of this margin is only an apparent phenomenon. Except for the outer basin, extension by dike injection coupled with high strength of the thin, pre-opening crust in the Vdring Basin precluded the formation of a faulted rift unconformity. We believe these observations have relevance for volcanic margins elsewhere, but infer that seaward-dipping reflectors can form in many environments.The Wring Plateau marginal high and other similar features in the North Atlantic are an integrated part of the North Atlantic Volcanic Province, which extends 2000 km longitudinally. Compared to the central, transverse, part of ...

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“…Cochran and Talwani [1978] propose an asthenospheric thermal anomaly of 50-80øC, while Zielinski [ 1979] argues that a temperature anomaly to a depth of 400 km may be needed to reproduce the observed bathymetry and gravity in the Norwegian-Greenland Sea. The thermal modeling applied to the gravity models assumes the asthenosphere to be homogeneous along the length of the modeled transects.…”

Section: The Thermal Modelmentioning

confidence: 99%

Effect of thermal contrasts on gravity modeling at passive margins: Results from the western Barents Sea

Breivik¹,

Verhoef²,

Faleide³

1999

J. Geophys. Res.

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Abstract. The western Barents Sea passive margin is a key locality to demonstrate the effect of the thermal structure of the lithosphere on forward gravity modeling. This margin developed by shear motion between the Eurasian and Greenland plates during the early Tertiary, and it is a significant border zone between young, hot oceanic lithosphere and cooler continental lithosphere. We construct two-dimensional gravity models of 125 km thick lithosphere based on expansion of mantle rocks determined from thermal modeling. The approach has a substantial impact over traditional shallow gravity models, here demonstrated on a previously published model. On the basis of a 140 mGal free-air anomaly, the old model proposes an anomalous, high-density oceanic crust emplaced in a leaky transform adjacent to the continent during early margin development. However, the lithospheric models predict a homogeneous oceanic crust, while preserving regional isostasy at base lithosphere from continent to ocean. Two further tests agree with this conclusion: A map of Bouguer corrected ERS-1 satellite data reveals no residual anomalies originating from the oceanic crust at the margin. Admittance analysis shows a strong oceanic lithosphere, and the high coherence between bathymetry and free-air gravity discounts a significant subsurface load. The high gravity anomalies at the margin are thus an edge effect, enhanced by sedimentation onto the strong oceanic lithosphere, and shaped by the effect of the lithospheric thermal field. Other results of this work include a new continent-ocean boundary map and two crustal transects across the margin.

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On the thermal evolution of passive continental margins, thermal depth anomalies, and the Norwegian‐Greenland Sea

Cited by 18 publications

References 34 publications

Heat flow in the Vøring Basin, Mid-Norwegian Shelf

Heat flow in the Vøring Basin, Mid-Norwegian Shelf

Evolution of the Vøring Volcanic Margin

Effect of thermal contrasts on gravity modeling at passive margins: Results from the western Barents Sea

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