The Goban Spur transect: Geologic evolution of a sediment-starved passive continental margin

Graciansky, P. C. de; Poag, C. Wylie; Cunningham, Robert; Loubere, Paul; Masson, Douglas G.; Mazzullo, Jim; Montadert, L.; Müller, Carla; Otsuka, Kenichi; Reynolds, Leslie; Sigal, Jacques; Snyder, Scott W.; Townsend, H. A.; Vaos, Stephanos P.; Waples, Douglas

doi:10.1130/0016-7606(1985)96<58:tgstge>2.0.co;2

Cited by 48 publications

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“…The timing of rifting is constrained by the earliest syn‐rift sediment recovered from Deep Sea Drilling Program (DSDP) Site 549 of late Hauterivian/early Barremian age (de Graciansky et al 1985) and the earliest post‐rift sediments present west of the continental slope: late Albian chalks and uppermost Albian mudstones overlying basalt at DSDP Site 550 (de Graciansky et al 1985). The youngest syn‐rift sediments observed were late Barremian, but the end of rifting cannot be well constrained due to an unconformity covering all of the Aptian and some of the Barremian (∼12 Myr).…”

Section: Geological Settingmentioning

confidence: 99%

“…Stage boundaries were converted to absolute time using the timescale of Gradstein et al (1994), placing the start of rifting at 128–126 Ma and the end at 112–106 Ma, a rift duration of 14–22 Myr. Approximately 120 km exists between normal oceanic crust and the foot of the slope, calculated from the distance between continental fault blocks and magnetic anomaly 34r (123±5 km) and the duration between the end of continental rifting and the formation of anomaly 34r as constrained by the latest syn‐rift sediment packages and the earliest sediment to the west of the slope (20.5–28.5 Myr) (de Graciansky et al 1985). The initial spreading rate immediately post rifting and assuming symmetrical spreading is 10 ± 2 mm yr −1 (full‐spreading rate).…”

Section: Geological Settingmentioning

confidence: 99%

“…A 20‐km‐wide body is clearly visible on seismic reflection line WAM (Western Approaches Margin; Klemperer & Hobbs 1991) at the foot of the continental slope overlying, and possibly intruding, thinned continental crust. Basaltic lava flows and pillows were recovered from DSDP Site 551 (de Graciansky et al 1985). These basalts have been described as oceanic thoeliites based on their geochemical signature (Maury et al 1985) but, depending on the mechanism of late‐stage margin evolution, their presence may not be a reliable indicator of the onset of full seafloor spreading.…”

Section: Geological Settingmentioning

confidence: 99%

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From continental extension to seafloor spreading: crustal structure of the Goban Spur rifted margin, southwest of the UK

Bullock

Minshull

2005

Geophysical Journal International

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S U M M A R YWe present a 169-km wide-angle velocity model across the Goban Spur rifted margin, southwest of the UK. A 120-km-wide intermediate region is identified between the first clear seafloor spreading magnetic anomaly (anomaly 34r) and thinned continental crust, where velocities increase from 4.5 km s −1 to 6.8 km s −1 in the top 4 km beneath acoustic basement. At depth it can be divided into a region where a 1.5-km-thick high-velocity layer (7.2-7.6 km s −1 ) exists and a region where this layer is absent but velocities of ∼7 km s −1 are present. Wide-angle PmP arrivals are observed across the whole of the intermediate region but a normal incidence reflection Moho is not present.Based on these velocities and combined with seismic reflection, gravity and magnetic modelling along this transect we interpret the intermediate region to consist of a 70 km wide zone of exhumed mantle with high Poisson's ratio at top basement (>0.34), an extremely low topographic expression and a high-velocity deep layer. Empirical relationships between velocity and degree of serpentinization suggest that serpentinite content decreases with depth from 100 per cent at top basement to <25 per cent from 5-7 km into basement. The observed magnetic anomaly is best fit by a thin magnetized layer (1 km) of magnetization 2-3 A m −1 . The intense magnetization may be due to magnetite formation during a prolonged interaction of serpentinite with sea water. Between this exhumed mantle and anomaly 34r is a 50-km-wide region raised 400 m above the adjacent exhumed mantle, consisting of a series of basement ridges. Poisson's ratio is not well defined in this region, which may be composed of anomalous oceanic crust or exhumed mantle.

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Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

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From continental extension to seafloor spreading: crustal structure of the Goban Spur rifted margin, southwest of the UK

Bullock

Minshull

2005

Geophysical Journal International

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“…Only the base of the coral banks has been dated with a Late Pliocene age (Kano et al 2007). However, on Goban Spur and adjacent deep-water basins, series of Pliocene clastic deposits were recovered with only a comparatively short Early Pliocene C10 erosion (de Graciansky et al 1985;Shannon et al 2007;Stoker et al 2002;Stoker et al 2005). Moreover, on the Enya mound site, the seismic profiles recorded probably the thickest (and most complete?)…”

Section: Evolutionary Stages Of the Enya Moundsmentioning

confidence: 98%

The Enya mounds: a lost mound-drift competition

Rooij

Huvenne

Blamart

et al. 2008

Int J Earth Sci (Geol Rundsch)

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The genesis and evolution of cold-water coral banks along the Northeastern Atlantic margin is known to be influenced by several factors, among which the palaeotopography and nature of the coral settling surface, the presence of bottom currents and sediment supply. In this paper, a case study is presented of the Enya mound cluster, located in the southernmost tip of the Belgica mound province, west of Ireland. Below this mound cluster, seismic stratigraphy revealed a yet unmapped local unconformity RD1b, being part of a composite erosion event (RD1). As such, from the Late Miocene to Late Pliocene, at least two erosional events have incised the margin, ending with the final RD1a ''moundbase'' unconformity, acting as a base for the Enya mounds. During the Quaternary the mounds became outgrown and were covered by a mounded contourite drift. In addition, they are closely associated with a cluster of seabed pockmarks. The bottom current regime which became active since the Middle Pleistocene has certainly influenced the fate of this mound cluster. The occurrence of the pockmarks seems to be related to relatively recent fluid migration processes, however leaving an open question if any previous seepage phases were involved in the growth or initiation of the coral banks.

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“…For example, in the Santander basin of northern Spain, carbonate deposition was reestablished during the Aptian with the formation of the "Urgonian Complex" (Pujalte, 1981(Pujalte, , 1985Pascal, 1983). On the Goban Spur, DSDP Site 549 recovered lower Barremian to Albian calcareous siltstone and Cenomanian and younger chalk overlying lower Barremian to upper Hauterivian noncalcareous sandy mudstone (de Graciansky et al, 1985).…”

Section: Influx Of Carbonate Sandmentioning

confidence: 99%

Composition of Lower Cretaceous Sandstone, Galicia Margin

Johnson¹

1988

Proceedings of the Ocean Drilling Program

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The composition of 31 samples of Lower Cretaceous (Valanginian to Aptian) sandstone from ODP Sites 638 through 641 was analyzed using the Gazzi-Dickinson point-counting method. The results show that the source of the Valanginian to Hauterivian sand was a continental block, dominated by granitic and/or high-grade-metamorphic rocks. Although these petrologic results do not allow discrimination between various potential continental block provinces, they suggest, in conjunction with seismic profiles and regional considerations, that the source was the Galicia margin or western Iberia. In contrast, the Barremian and Aptian sand is dominated by carbonate grains that were derived from a carbonate platform, probably on Galicia Bank.

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The Goban Spur transect: Geologic evolution of a sediment-starved passive continental margin

Cited by 48 publications

References 0 publications

From continental extension to seafloor spreading: crustal structure of the Goban Spur rifted margin, southwest of the UK

From continental extension to seafloor spreading: crustal structure of the Goban Spur rifted margin, southwest of the UK

The Enya mounds: a lost mound-drift competition

Composition of Lower Cretaceous Sandstone, Galicia Margin

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