New Somali Basin magnetic anomalies and a plate model for the early Indian Ocean

Davis, J. K.; Lawver, Lawrence A.; Norton, Ian O.; Gahagan, Lisa M.

doi:10.1016/j.gr.2016.02.010

Cited by 67 publications

(107 citation statements)

References 59 publications

Supporting

Mentioning

102

Contrasting

Order By: Relevance

“…The location of the spreading axis first derived from seismic, gravity, and magnetic data in the 80s (Cochran, ) has been confirmed by satellite‐derived, free‐air gravity data (Davis et al, ; Phethean et al, ; Sauter et al, ). Spreading was directed N‐S before the extinction, but a NNW‐SSE direction is inferred from gravity lineaments in the older oceanic crust fabric close to the Somalian margin (Figure ) (Davis et al, ; Gaina et al, ; Phethean et al, ; Seton et al, ). The age of this change of spreading direction is estimated to be 155–150 Ma in the WSB (Davis et al, ; Phethean et al, ; Reeves et al, ).…”

Section: Geological Backgroundmentioning

confidence: 99%

Intraplate Deformation of Oceanic Crust in the West Somali Basin: Insights From Long‐offset Reflection Seismic Data

et al. 2018

View full text Add to dashboard Cite

Interpretation of new high‐resolution seismic reflection sections reveals intraplate deformation of oceanic crust in the West Somali Basin, between the East Africa margin and the Davie Ridge and its northern extension. The deformation of the oceanic crust takes the form of 1–2 km amplitude buckle folds with a 20–30 km wavelength associated with thrust faults. Reverse faulting is localized along deformation corridors, about 15–30 km wide that we interpret as inherited oceanic fracture zones of the extinct oceanic spreading center. Deformation of the oceanic crust in the westernmost segment started before Hauterivian time (~132 Ma), while oceanic accretion was ongoing to the east of the Davie Ridge, and stopped at Aptian time (~120 Ma), when spreading ceased in the whole Somali Basin. Prior to the deformation of the oceanic crust, large volcanic edifices have been emplaced on top of the oceanic crust along preexisting oceanic fracture zones. Well‐defined groups of reflectors, within the mantle (<~20 km below top basement), are interpreted as large shear zones that tapped a connection to deep lithospheric melt channels leading to magmatic intrusions within the crust and emplacement of postseafloor‐spreading volcanic edifices within deformation corridors.

show abstract

Section: Geological Backgroundmentioning

confidence: 99%

Intraplate Deformation of Oceanic Crust in the West Somali Basin: Insights From Long‐offset Reflection Seismic Data

et al. 2018

View full text Add to dashboard Cite

show abstract

“…Several plate kinematic models describe the breakup of Gondwana along the East African margin (e.g., Cox, 1992;Davis et al, 2016;Gaina et al, 2013Gaina et al, , 2015Eagles and König, 2008;Leinweber and Jokat, 2012;Nguyen et al, 2016;Reeves et al, 2016). It is generally accepted that the breakup of Gondwana along the East African margin took place in the Early Jurassic at about 170-180 Ma (e.g., Gaina et al, 2013Gaina et al, , 2015Leinweber and Jokat, 2012;Leinweber et al, 2013;Nguyen et al, 2016;Reeves et al, 2016).…”

Section: Breakup Of East and West Gondwanamentioning

confidence: 99%

“…However, a consistent reconstruction of pre-rift configurations relies on the knowledge of the crustal types and the location and structural style of the continent-ocean boundaries. Therefore, the early movements within Gondwana are poorly constrained and there is a debate about the timing and directions of the earliest rifting and spreading phases (e.g., Cox, 1992;Davis et al, 2016;Eagles and König, 2008;Jokat et al, 2003;Leinweber and Jokat, 2012;Marks and Tikku, 2001;Martin and Hartnady, 1986;Nguyen et al, 2016;Phethean et al, 2016;Reeves, 2014;Reeves et al, 2016;Roeser et al, 1996;Smith and Hallam, 1970;Torsvik and Cocks, 2013). The Mozambique Basin is of special importance for Gondwana reconstructions, as two end-members of rifted margins, a volcanic rifted and a transform margin, can be studied in the immediate vicinity.…”

Section: Introductionmentioning

confidence: 99%

Tie points for Gondwana reconstructions from a structural interpretation of the Mozambique Basin, East Africa and the Riiser-Larsen Sea, Antarctica

Klimke

Franke

Mahanjane³

et al. 2018

Solid Earth

View full text Add to dashboard Cite

Abstract. Movements within early East Gondwana dispersal are poorly constrained, and there is debate about conjugate geologic structures and the timing and directions of the rifting and earliest seafloor spreading phases. We present a combined structural interpretation of multichannel reflection seismic profiles from offshore of northern Mozambique (East Africa) and the conjugate Riiser-Larsen Sea (Antarctica). We find similar structural styles at the margins of both basins. At certain positions at the foot of the continental slope close to the continent-ocean transition, the basement is intensely deformed and fractured, a structural style very untypical for rifted continental margins. Sediments overlying the fractured basement are deformed and reveal toplap and onlap geometries, indicating a post-breakup deformation phase. We propose this unique deformation zone as a tie point for Gondwana reconstructions. Accordingly, we interpret the western flank of Gunnerus Ridge, Antarctica as a transform margin similar to the Davie Ridge offshore of Madagascar, implying that they are conjugate features. As the continental slope deformation is post-rift, we propose a two-phase opening scenario. A first phase of rifting and early seafloor spreading, likely in NW-SE direction, was subsequently replaced by a N-S-directed transform deformation phase overprinting the continent-ocean transition. From previously identified magnetic chrons and the sediment stratigraphy, this change in the spreading directions from NW-SE to N-S is suggested to have occurred by the late Middle Jurassic. We suggest that the second phase of deformation corresponds to the strikeslip movement of Madagascar and Antarctica and discuss implications for Gondwana breakup.

show abstract

“…Of the published ocean magnetic anomaly interpretations, those by Sègoufin and Patriat [], Cochran [], and Davis et al . [] show strong similarities to each other, with the basin's center of symmetry lying around M0 and the oldest anomalies detected in the basin reaching between M21 and M24. Rabinowitz et al .…”

Section: Data and Processingmentioning

confidence: 99%

Madagascar's escape from Africa: A high‐resolution plate reconstruction for the Western Somali Basin and implications for supercontinent dispersal

Phethean

Kalnins

Hunen

et al. 2016

Geochem Geophys Geosyst

View full text Add to dashboard Cite

Accurate reconstructions of the dispersal of supercontinent blocks are essential for testing continental breakup models. Here, we provide a new plate tectonic reconstruction of the opening of the Western Somali Basin during the breakup of East and West Gondwana. The model is constrained by a new comprehensive set of spreading lineaments, detected in this heavily sedimented basin using a novel technique based on directional derivatives of free‐air gravity anomalies. Vertical gravity gradient and free‐air gravity anomaly maps also enable the detection of extinct mid‐ocean ridge segments, which can be directly compared to several previous ocean magnetic anomaly interpretations of the Western Somali Basin. The best matching interpretations have basin symmetry around the M0 anomaly; these are then used to temporally constrain our plate tectonic reconstruction. The reconstruction supports a tight fit for Gondwana fragments prior to breakup, and predicts that the continent‐ocean transform margin lies along the Rovuma Basin, not along the Davie Fracture Zone (DFZ) as commonly thought. According to our reconstruction, the DFZ represents a major ocean‐ocean fracture zone formed by the coalescence of several smaller fracture zones during evolving plate motions as Madagascar drifted southwards, and offshore Tanzania is an obliquely rifted, rather than transform, margin. New seismic reflection evidence for oceanic crust inboard of the DFZ strongly supports these conclusions. Our results provide important new constraints on the still enigmatic driving mechanism of continental rifting, the nature of the lithosphere in the Western Somali Basin, and its resource potential.

show abstract

New Somali Basin magnetic anomalies and a plate model for the early Indian Ocean

Cited by 67 publications

References 59 publications

Intraplate Deformation of Oceanic Crust in the West Somali Basin: Insights From Long‐offset Reflection Seismic Data

Intraplate Deformation of Oceanic Crust in the West Somali Basin: Insights From Long‐offset Reflection Seismic Data

Tie points for Gondwana reconstructions from a structural interpretation of the Mozambique Basin, East Africa and the Riiser-Larsen Sea, Antarctica

Madagascar's escape from Africa: A high‐resolution plate reconstruction for the Western Somali Basin and implications for supercontinent dispersal

Contact Info

Product

Resources

About