Insight into the Eastern Margin of Africa from a new tectonic model of the Indian Ocean

Abstract

We present a new plate tectonic model for the breakup and dispersal of East and West Gondwana and subsequent formation of the Indian Ocean, focussed on the early evolution of the Eastern Margin of Africa. We start from a tight reconstruction of all the Precambrian pieces. Using primarily ocean-floor fracture zone data, the development of the ocean between India and Antarctica is resolved into four distinct spreading regimes and that between Antarctica and Africa into seven distinct regimes. The movement of Madagascar against Africa is then investigated as part of the plate–circuit closure between Africa and India in the Madagascar–Africa–Antarctica–India–Madagascar system. We conclude that a distinct change in plate tectonic regime off East Africa occurred at about 153 Ma (Kimmeridgian) when transforms were first activated offshore. Before this time, East and West Gondwana were separated by a rift, propagating from NE to SW and starting between 188 and 170 Ma. The model is defined by Euler interval poles, published here for the first time, and a refined global animation that may be inspected and copied from the URL www.reeves.nl/Gondwana. The analysis points to a small number of disruptive events in the otherwise inexorable growth of the oceans.

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

“…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).…”

“…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). While earlier studies proposed that the Mozambique Basin and West Somali Basin opened in a generally N-S direction, more recent plate tectonic reconstructions argue for an almost simultaneous opening of both basins in the NW-SE direction (e.g., Gaina et al, 2013;Reeves et al, 2016). There is also debate about the timing and directions of the earliest rifting and spreading phases.…”

“…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.…”

Transform margins: development, controls and petroleum systems – an introduction

“…This volume attempts to enhance the knowledge reviewed in the previous text by studying the African and South American conjugates of the Romanche and St Paul transform fault zone (Davison et al 2015;Dickson et al 2016;Nemčok et al 2015b), the Guyana and Suriname transform faults zones (Dickson et al 2016;Loncke et al 2015;Nemčok et al 2015a, c), the French Guyana hyper-oblique margin (Sapin et al 2016), transform margins of the Arctic region (Doré et al 2015), the Andaman Sea transform margin (Morley 2015), the Coromandal transform margin , transtensional margin between the Caribbean and North American plates (Sanchez et al 2015), the Davie transform margin and its neighbour transform margins (Reeves et al 2016), studying transform behaviour by a review of multiple worldwide cases (Nemčok et al 2016) and parametric numerical modelling .…”

“…Studying a multi-stage ocean opening, Doré et al (2015) focus on the role of multiple consecutive tectonic events controlled by different stress regimes in microcontinent release. Utilizing a plate reconstruction technique and reflection seismic interpretation, Reeves et al (2016) also study the role of multiple tectonic events on the breakup geometry. Nemčok et al (2015a) document a role of wrench faulting in control of the ocean segment terminus.…”