Advanced insights into magmatism and volcanism of the Mozambique Ridge and Mozambique Basin in the view of new potential field data

Abstract

S U M M A R YA new plate tectonic model is presented which describes the emplacement of the Mozambique Ridge off southeast Africa as the result of long lasting volcanic activity (140-122 Ma) during the initial opening between Africa and Antarctica. Thus, an oceanic origin for the Mozambique Ridge is proposed. This model is based on a new and systematic high resolution magnetic anomaly data set acquired across the Mozambique Ridge and throughout the Mozambique Basin.Data from the Mozambique Basin allow the identification of Mesozoic magnetic anomalies from M0r to M26 (124.61-155.3 Ma) with previously unmatched accuracy. Small-scale fracture zones are recognized by offsets of magnetic anomalies in the westernmost part of the basin. Additionally, a bend in the major fracture zones 'F' and 'E' between M17r and M18n (142.84-144.04 Ma) and a recognized sinusoidal change in spreading direction with an amplitude of about 15 • indicate that the basin experienced several small scale changes in spreading direction through time. A maximum change in spreading direction to almost 0 • at around M11n (135.69 Ma) is followed by a short lived increase in spreading half rate from 23.5 km Ma −1 to about 27.5 km Ma −1 in the time frame from M10r to . We propose that this is related to the initial opening of the South Atlantic Ocean represented by the onset of seafloor spreading between the Falkland Plateau and Africa in the conjugate Georgia and Natal basins.Across the Mozambique Ridge, high amplitude magnetic anomalies at major structural boundaries suggest that the different plateaus of the ridge were formed at different times. A simple 2-D gravity and magnetic model for the ridge supports the hypothesis of multiple volcanic episodes which formed the ridge though long lasting volcanic activity between about 140 and 122 Ma. Together with new and verified rotation parameters from the Mozambique Basin and its conjugate, the Riiser-Larsen Sea, Antarctica, a series of plate tectonic reconstructions are presented which demonstrate when and how the different parts of the ridge evolved through time.

Growth and Dispersal of a Southeast African Large Igneous Province

“…by Marks and Tikku, 2001;König and Jokat, 2006), the MOZR was treated as a continental microplate which had an independent motion between M11 and M2 (133 to 124 Ma) (Marks and Tikku, 2001) and which was located in close vicinity of an extinct spreading center. König and Jokat (2010) present new magnetic data from the MOZR and the Mozambique Basin to its northeast, which indicate a volcanic formation of the rise between 140 and 122 Ma. In our model ( Figure 5), for which the rotation parameters of König and Jokat (2006;2010) are applied, the MOZR must have reached its own maximum extent by about 120 Ma while the Antarctic-African spreading zone ran beneath its eastern flank.…”

“…König and Jokat (2010) present new magnetic data from the MOZR and the Mozambique Basin to its northeast, which indicate a volcanic formation of the rise between 140 and 122 Ma. In our model ( Figure 5), for which the rotation parameters of König and Jokat (2006;2010) are applied, the MOZR must have reached its own maximum extent by about 120 Ma while the Antarctic-African spreading zone ran beneath its eastern flank. Parts of the Astrid Ridge were possibly attached and developed as part of the same magmatic process.…”

“…Although plate-kinematic studies adopted a continental MOZR and placed the MOZR adjacent to the Astrid Ridge of Dronning Maud Land in Antarctica (Marks and Tikku, 2001;König and Jokat, 2006), a continental block of substantial size, as the entire MOZR would be, does not allow a close fit in the pre-breakup position of Africa and Antarctica. König and Jokat (2010) analysed new densely-spaced magnetic survey data across the MOZR and the Mozambique Basin and excluded the presence of major continental blocks throughout the MOZR.…”

Palaeoceanographic Interpretation of a Seismic Profile From the Southern Mozambique Ridge, Southwestern Indian Ocean

“…A deep water passage between the Indian and South Atlantic Oceans was created after the separation of the Falkland Plateau from Africa at 110 to 100 Ma (König and Jokat, 2006).…”

Sedimentation and potential venting on the rifted continental margin of Dronning Maud Land

“…A magmatic pulse formed the Maud Rise large igneous province at 65°S, 3°E well after breakup. Off the conjugate margin, the volcanic Mozambique Ridge formed by southwards stepwise migration of a volcanic centre (König and Jokat 2010). These processes are currently not understood in great detail, but they have undoubtedly had a strong impact on the structure and geodynamic development of the DML margin and its neighbouring deep-sea basins.…”