Initial Reports of the Deep Sea Drilling Project, 36

Barker, P.F.; Dalziel, Ian W. D.

doi:10.2973/dsdp.proc.36.1977

Cited by 125 publications

(18 citation statements)

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“…It is correlated with the base of the Middle Inoceramus Formation in the Magallanes Basin which is placed within the Cenomanian by Biddle et al (1986). By extrapolation it is correlated with the U3 unconformity of the Falkland Plateau Basin, which corresponds to a Mid-Cretaceous lacuna identified in DSDP boreholes (Barker et al 1977;Lorenzo & Mutter 1988).…”

Section: End Rift Unconformity (Mid-cretaceous Unconformity)mentioning

confidence: 96%

“…Correlation has been made with adjacent and related basins in southern South America and southern Africa, the outcrop geology of the Falkland Islands (Greenway 1972) and the DSDP boreholes drilled in Legs 36 (327, 329 and 330) and 71 (511 and 512) on the flanks of the Maurice Ewing Bank and Falkland Plateau Basin (Barker et al 1977). Regional scientific seismic data acquired by the Lamont-Doherty Geological Observatory over the central and eastern Falkland Plateau (Lorenzo & Mutter 1988) have also been helpful in regional extrapolation.…”

Section: Shelfmentioning

confidence: 99%

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Tectono-stratigraphic evolution of the North Falkland region

Lawrence¹,

Johnson

Tubb³

et al. 1999

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An interpretation of regional seismic data acquired between 1993 and 1995 has been used to establish a regionally consistent tectono-stratigraphic framework for the North Falkland Shelf. This incorporates three rift (extensional) and two post-rift sequences separated by important tectono-stratigraphic breaks representing unconformities at near-Base Upper Jurassic, near-Base Cretaceous, Mid-Cretaceous and Early Tertiary levels. In the structural framework derived from seismic interpretation two major zones are recognized. The northeast Graben Zone constitutes three tectono-stratigraphic provinces, the north-south orientated North Falkland Graben, and the Western Rift Complex and Southern Half-graben which are dominated by northwest-southeast rift trends. The Falkland Islands form part of the southwest Uplift Zone which has a tectono-stratigraphic history, shown by the interpretation of apatite fission track data, to be compatible with that of the North Falkland Shelf and southern South America. A regional northeast-southwest seismic line shows an extensional northern edge to the Falkland Plateau and no apparent westerly extension of the Agulhas-Falkland Fracture Zone. A ‘rigid’ or ‘non-rotational’ reconfiguration of southwest Gondwanaland (i.e. with no independent rotation of a Falkland Islands microplate) shows a regional consistency of Late Triassic-Mid-Jurassic back-arc and Late Jurassic-Early Cretaceous South Atlantic rift trends. This is presented as circumstantial evidence for a ‘non-rotational’ model for the break-up of southwest Gondwanaland.

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Section: End Rift Unconformity (Mid-cretaceous Unconformity)mentioning

confidence: 96%

Section: Shelfmentioning

confidence: 99%

Tectono-stratigraphic evolution of the North Falkland region

Lawrence¹,

Johnson

Tubb³

et al. 1999

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“…South of the FAFZ anomalies are only recognized out to A21 on the western flank and A13 in the east, but over this range show no ridge jumps and an asymmetry essentially similar in sense and magnitude to that to the north. The only other relevant data, from DSDP site 328, about 240 km east of the Falkland Plateau and south of the FAFZ, merely suggest that the Plateau's eastern margin is the original one, and that the ocean floor between there and the site has not been disrupted by a subsequent ridge jump (Barker, Dalziel et al 1977). In summary, therefore, 1200 km of ridge offset were eliminated by anomalous spreading south of the FAFZ, probably between 110 and 50 Ma ago.…”

Section: Introductionmentioning

confidence: 94%

“…The Falkland Plateau is now known from direct drilling (Barker, Dalziel et al 1977) to be of continental origin. Its northern margin, and the FAFZ which extends eastward from there to the south-eastern African margin (Fig.…”

Section: Introductionmentioning

confidence: 99%

The history of ridge-crest offset at the Falkland--Agulhas Fracture Zone from a small-circle geophysical profile

Barker

1979

Geophysical Journal International

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Summary. The magnetic and bathymetric profiles are described along a single ship track following a small circle of South Atlantic opening about 100 km south of the Falkland‐Agulhas Fracture Zone (FAFZ). The magnetic anomalies reveal a 700 km westward jump of the crest of the Mid‐Atlantic Ridge at about 61–64 Ma ago and suggest a second 100 km westward jump 58–60 Ma ago. The destinations of both jumps are now occupied by narrow rough‐topped ridges standing about 2 km above the adjacent ocean floor. It is suggested that these were formed at the times of the jumps, by volcanic and intrusive igneous activity associated with the rupture of older oceanic crust. The original offset of the ridge crest at the FAFZ was 1400 km, the length of the continental Falkland Plateau; of this only about 200 km remains. 800km of offset was eliminated by the two ridge jumps already detected, leaving 400 km unaccounted for. Under reasonable assumptions, a further westward ridge jump of 380 km at about 98 Ma is proposed, the destination of which is marked by the only other similarly anomalous elevations on the bathymetric profile, one of which is the Agulhas Plateau. Existing sediment samples from the Agulhas Plateau are consistent with this interpretation of its origin. Magnetic anomalies directly east of the Falkland Plateau are identical to those in the eastern Cape Basin, which suggests strongly that the South Atlantic spreading system extended some distance south of the FAFZ from its inception. The anomalous elevations extend about 600 km south of the FAFZ indicating the southward extent of the ridge jumps and perhaps therefore of the spreading system at 98 and 60 Ma. In many ways the elevations resemble others commonly identified as hotspot phenomena, some of which may also have formed initially at ridge jump destinations. The correspondence between the observed magnetic profile and a synthetic profile generated from the LaBrecque time scale is particularly good for the past 40 Ma. This allows a detailed comparison; using the enhanced sensitivity of a reduced distance plot, which reveals several departures from linearity. Some revision of the LaBrecque time scale may be required. The reduced distance plot also shows details of the asymmetric spreading which, being of the same degree and in the same sense on both sides of the FAFZ, did not change the offset significantly. The asymmetry resembles that found south of Australia in being without discernible ridge jumps but displaying abrupt changes in degree, and in that the more slowly accreting (African) plate is the more elevated.

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“…1; Barker et al 1976). These rocks have not been accurately dated, but the lithologies (gneiss, granitoids) and isotopic compositions are similar to those found in the Mesoproterozoic (c. 1.1 Ga) Cape Meredith Complex, which is exposed on the southern tip of West Falkland (Wareham et al 1998;Jacobs et al 1999;Thomas et al 2000).…”

Section: Basementmentioning

confidence: 99%

The three-dimensional lithospheric structure of the Falkland Plateau region based on gravity modelling

Kimbell

Richards

2008

JGS

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Abstract:The lithospheric structure of the Falkland Plateau region has been modelled by making an initial estimate on the basis of local isostasy and then refining the geometries by inversion of gravity anomalies. The model predicts a crustal thickness beneath the Falkland Plateau Basin that is more than twice that previously inferred from seismic evidence. The preferred explanation is that the seismic survey detected high-velocity (?underplated) lower crust rather than upper mantle. This is compatible with the results of deep seismic experiments over the conjugate Filchner Block of Antarctica and also appears likely on the basis of the position of the Falkland Plateau Basin in relation to the Karoo-Ferrar magmatic province at the time of extension. Continental crust is inferred to be continuous beneath the northern part of the Falkland Plateau, as there are consistent magnetic and flexural anomalies associated with the continent-ocean boundary. Flexural modelling of the southern margin of the plateau indicates lateral variations in strength, with the strongest lithosphere beneath the Falkland Plateau Basin. This may indicate thick oceanic crust beneath the southern part of the basin or the effect of thinning relatively weak continental crust and replacing it with relatively strong underplating. [End of Abstract]

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Initial Reports of the Deep Sea Drilling Project, 36

Cited by 125 publications

References 0 publications

Tectono-stratigraphic evolution of the North Falkland region

Tectono-stratigraphic evolution of the North Falkland region

The history of ridge-crest offset at the Falkland--Agulhas Fracture Zone from a small-circle geophysical profile

The three-dimensional lithospheric structure of the Falkland Plateau region based on gravity modelling

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