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

• Published in: Geophysical Journal International
• Main Authors: Koenig, Matthias, Jokat, Wilfried
• Format: Text
• Language: English
• Published: Wiley-blackwell Publishing, Inc 2010
• Subjects: geo; envir; Falkland Plateau; Riiser-Larsen; Riiser-Larsen Sea; Antarc*; Antarctica; South Atlantic Ocean
• Online Access: https://doi.org/10.1111/j.1365-246X.2009.04433.x; https://archimer.ifremer.fr/doc/00231/34261/32626.pdf; https://archimer.ifremer.fr/doc/00231/34261/

P>A 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 degrees indicate that the basin experienced several small scale changes in spreading direction through time. A maximum change in spreading direction to almost 0 degrees 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 M9n (134.30-132.83 Ma). 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 ...