Site 353: Vema Fracture Zone

Perch-Nielsen, K.; Supko, P.R.; Boersma, Alexandra T.; Bonatti, Enrico; Carlson, R. L.; McCoy, Floyd W.; Neprochnov, Y.P.; Zimmerman, Herman

doi:10.2973/dsdp.proc.39.102.1977

Cited by 8 publications

(2 citation statements)

References 16 publications

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“…Karson & Dick (1983), reported significant thicknesses of basaltic rubble in the Kane fracture zone, presumably debris from the fracture zone walls. Similar rubble was observed during submarine investigations of the Oceanographer transform valley (OTTER 1984(OTTER , 1986 and also encountered during drilling in the Vema by DSDP (Perch-Nielson et al 1977). The accumulation of' this low velocity material on top of fractured and faulted crust would further reduce the apparent velocity of the crust.…”

Section: R U S T a L S T R U C T U R E B E N E A T H T H E F R A C supporting

confidence: 55%

Crustal structure of Atlantic fracture zones--II. The Vema fracture zone and transverse ridge

Potts

White

Louden

1986

Geophysical Journal International

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The crustal structure beneath the Vema fracture zone and its flanking transverse ridge was determined from seismic refraction profiles along the fracture zone valley and across the ridge. Relatively normal oceanic crust, but with an upwarped seismic Moho, was found under the transverse ridge. We suggest that the transverse ridge represents a portion of tectonically uplifted crust without a major root or zone of serpentinite diapirism beneath it. A region of anomalous crust associated with the fracture zone itself extends about 20 km to either side of the central fault, gradually decreasing in thickness as the fracture zone is approached. There is evidence to suggest that the thinnest crust is found beneath the edges of the 20 km wide fracture zone valley. Under the fracture zone valley the crust is generally thinner than normal oceanic crust and is also highly anomalous in its velocity structure. Seismic layer 3 is absent, and the seismic velocities are lower than normal. The absence of layer 3 indicates that normal magmatic accretionary processes are considerably modified in the vicinity of the transform fault. The low velocities are probably caused by the accumulation of rubble and talus and by the extensive faulting and fracturing associated with the transform fault. This same fracturing allows water to penetrate through the crust, and the apparently somewhat thicker crust beneath the central part of the fracture zone valley may be explained by the resultant serpentinization having depressed the seismic Moho below its original depth.

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Section: R U S T a L S T R U C T U R E B E N E A T H T H E F R A C supporting

confidence: 55%

Crustal structure of Atlantic fracture zones--II. The Vema fracture zone and transverse ridge

Potts

White

Louden

1986

Geophysical Journal International

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“…Located at the western termination of the Carlsberg Ridge, this 330-km-long fault is part of the active plate boundary between India and Somalia. A key property of the Owen Transform Fault is that the transform fault valley is the far-end depocentre for the distal Indus turbidites (Figure 1), bearing resemblance to the Vema Transform Fault valley fed by the Amazon Cone and filled with ∼1,000 m of sediments (Bonatti et al, 2003(Bonatti et al, , 2005Perch-Nielsen et al, 1977). The Owen Transform Fault however represents an end-member case of a sedimented transform fault, with more than 5,000 m of sediments piled in the valley at its deepest point, providing an exceptional sedimentary record of the tectonic events through time.…”

mentioning

confidence: 99%

Tectonic Evolution of a Sedimented Oceanic Transform Fault: The Owen Transform Fault, Indian Ocean

et al. 2023

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Plate tectonics theory predicts that transform faults connecting mid-oceanic ridge segments are long-lasting steady-state features, since their length, side-to-side material contrast, rate and style are invariant as long as boundary conditions remain stable. In nature, transform faults formed in the early stage of oceanic basin opening commonly have lifespans of several tens of million years (Bonatti et al., 1994;Géli et al., 1997;Maia et al., 2016), in agreement with the theory. Furthermore, global plate models for past and current kinematics based on magnetics and geodesy point to relative kinematic stability over the last million years (DeMets et al., 2010), within the bounds of data uncertainties (such as errors in fault traces, magnetic pickings, focal mechanisms, GPS measurements).Yet, the multi-strand morphology of some of the longest transform faults bears witness to a complex geological evolution involving fault abandonment, fault growth, uplift of transverse and median ridges, formation of

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Flexural uplift of a lithospheric slab near the Vema transform (Central Atlantic): Timing and mechanisms

Bonatti

Brunelli

Buck

et al. 2005

Earth and Planetary Science Letters

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Site 353: Vema Fracture Zone

Cited by 8 publications

References 16 publications

Crustal structure of Atlantic fracture zones--II. The Vema fracture zone and transverse ridge

Crustal structure of Atlantic fracture zones--II. The Vema fracture zone and transverse ridge

Tectonic Evolution of a Sedimented Oceanic Transform Fault: The Owen Transform Fault, Indian Ocean

Flexural uplift of a lithospheric slab near the Vema transform (Central Atlantic): Timing and mechanisms

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