Formation of oceanic crust at slow spreading rates: New constraints from an extinct spreading center in the Labrador Sea

Louden, K. E.; Osler, John C.; Srivastava, S. P.; Keen, C. E.

doi:10.1130/0091-7613(1996)024<0771:foocas>2.3.co;2

Cited by 33 publications

(27 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The probable effect of serpentinization in lowering the effective strength of the mantle during late stages of rifting has not as yet been included in any model for lithospheric extension. Although the specific structures that we observe within the OCT of non-volcanic rifted margins differ from those created by oceanic rifts at very slow rates of spreading (Mutter & Karson 1992;Louden et al . 1996), some aspects of the rifting process may be similar.…”

Section: Discussionmentioning

confidence: 94%

The deep structure of non–volcanic rifted continental margins

Louden

Chian

1999

Philosophical Transactions of the Royal Society of London. Seri

Self Cite

View full text Add to dashboard Cite

Delineating the nature of crustal variations across passive continental margins is fundamental to our understanding of how the uppermost lithosphere deforms under extension. This information is best obtained across margins where the extensional fabric within the crust has not been significantly modified by large-scale syn-rift volcanism. Previous studies of such margins have shown a range of extensional styles, which have been interpreted by various combinations of pure and simple shearing of continental crust and lithosphere. This paper reanalyses several key transects in the North Atlantic, including the conjugate margin pairs of Newfoundland-Iberia, Flemish Cap-Goban Spur and Labrador-W. Greenland. Analysis of both deep multichannel seismic reflection and wide-angle reflection/refraction profiles allows us to produce new joint constructions of velocity and reflectivity depth sections. These sections indicate major asymmetries in the width and faulting style of continental rifting between margin conjugates. They also show a general occurrence of a complex transition zone between extended continental and oceanic crust that is dominated by exposed and serpentinized upper mantle. Because serpentinite has a much lower strength than is typical of continental or oceanic crustal rocks, its existence within the transition zone may have a profound influence on how these margins develop. The possible effects that such time and spatially variable rheologies have on the development of these margins needs to be considered in future geodynamical models.

show abstract

Section: Discussionmentioning

confidence: 94%

The deep structure of non–volcanic rifted continental margins

Louden

Chian

1999

Philosophical Transactions of the Royal Society of London. Seri

Self Cite

View full text Add to dashboard Cite

show abstract

“…Subsequent tectonic extension of these deposits could produce fault blocks similar to those found in continental extensional basins. However, Osler & Louden (1995) and Louden et al (1996) showed that in the case of the Labrador Sea ultra‐slow spreading crust, seismic phases corresponding to oceanic layer 3 are observed in wide‐angle data near the Srivastava & Keen (1995) profile. Thus the process noted above does not explain the absence of oceanic layer 3 on Line 1.…”

Section: Implications Of New Seismic Datamentioning

confidence: 96%

A deep seismic investigation of the Flemish Cap margin: implications for the origin of deep reflectivity and evidence for asymmetric break-up between Newfoundland and Iberia

Hopper¹,

Funck²,

Tucholke³

et al. 2006

Geophysical Journal International

View full text Add to dashboard Cite

SUMMARY Seismic reflection and refraction data were acquired along the southeast margin of Flemish Cap at a position conjugate to drilling and geophysical surveys across the Galicia Bank margin. The data document first‐order asymmetry during final break‐up between Newfoundland and Iberia. An abrupt necking profile of continental crust observed off Flemish Cap contrasts strongly with gradual tapering on the conjugate margin. There is no evidence beneath Flemish Cap for a final phase of continental extension that resulted in thin continental crust underlain by a strong ‘S’‐like reflection, which indicates that this mode of extension occurred only on the Galicia Bank margin. Compelling evidence for a broad zone of exhumed mantle or for peridotite ridges is also lacking along the Flemish Cap margin. Instead, anomalously thin, 3–4‐km‐thick oceanic crust is observed. This crust is highly tectonized and broken up by high‐angle normal faulting. The thin crust and rift structures that resemble the abandoned spreading centre in the Labrador sea suggest that initial seafloor spreading was affected by processes observed in present‐day ultra‐slow spreading environments. Landwards, Flemish Cap is underlain by a highly reflective lower crust. The reflectivity most likely originates from older Palaeozoic orogenic structures that are unrelated to extension and break‐up tectonics.

show abstract

“…Seafloor spreading at the Ran Ridge in the Labrador Sea ceased prior to anomaly 13 time (Kristofferson & Talwani 1977). Detailed study of the final spreading episode of the Ran Ridge suggests that the spreading slowed between chrons 21 and 13 (47-33 Ma) (Louden et al 1996). We assume that the slowing occurred linearly between chrons 21 and 13.…”

Section: Flowlinesmentioning

confidence: 99%

Ridge-plume interaction in the North Atlantic and its influence on continental breakup and seafloor spreading

Smallwood¹,

White

2002

108

View full text Add to dashboard Cite

Development of the rifted continental margins and subsequent seafloor spreading in the North Atlantic was dominated by interaction between the Iceland mantle plume and the continental and oceanic rifts. There is evidence that at the time of breakup a thin sheet of particularly hot asthenospheric mantle propagated beneath the lithosphere across a 2500 km diameter region. This event caused transient uplift, massive volcanism and intrusive magmatism, and a rapid transition from continental stretching to seafloor spreading. Subsequently, the initial plume instability developed to an axisymmetric shape, with the c. 100 km diameter central core of the Iceland plume generating 30-40 km thick crust along the Greenland-Iceland-Faroes Ridge. The surrounding 2000 km diameter region received the lateral outflow from the plume, causing regional elevation and the generation of thicker and shallower than normal oceanic crust. We document both long-term (10-20Ma) and short-term (3-5Ma) fluctuations in the temperature and/or flow rate of the mantle plume by their prominent effects on the oceanic crust formed south of Iceland. Lateral ridge jumps in the locus of rifting are frequent above the regions of hottest asthenospheric mantle, occurring in both the early history of seafloor spreading, when the mantle was particularly hot, and throughout the generation of the Greenland-lceland-Faroes Ridge.

show abstract

Formation of oceanic crust at slow spreading rates: New constraints from an extinct spreading center in the Labrador Sea

Cited by 33 publications

References 0 publications

The deep structure of non–volcanic rifted continental margins

The deep structure of non–volcanic rifted continental margins

A deep seismic investigation of the Flemish Cap margin: implications for the origin of deep reflectivity and evidence for asymmetric break-up between Newfoundland and Iberia

Ridge-plume interaction in the North Atlantic and its influence on continental breakup and seafloor spreading

Contact Info

Product

Resources

About