The initial Gondwana break-up; a synthesis based on new potential field data of the Africa-Antarctica Corridor

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doi: 10.1016/j.tecto.2018.11.008
Author(s): Mueller, Christian Olaf; Jokat, Wilfried
Author Affiliation(s): Primary:
Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
Volume Title: Tectonophysics
Source: Tectonophysics, Vol.750, p.301-328. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0040-1951 CODEN: TCTOAM
Note: In English. 142 refs.; illus., incl. 1 table, geol. sketch maps
Summary: The initial opening of the Africa-Antarctica Corridor, in the heart of Gondwana, is still enigmatic due to missing information on the origin of major crustal features and the exact timing of the onset of the first oceanic crust in the Jurassic. Therefore, in 2014, new ship-borne magnetic data were systematically acquired in the northern Mozambique Basin and across Beira High, which we merged with all accessible magnetic data in the Mozambique Basin. Herein, distinct magnetic lineations are observed, which allow a refined identification of a whole set of Jurassic magnetic spreading anomalies, constraining the timing of the onset of oceanization, beginning at M38n.2n (164.1 Ma). In combination with high-resolution potential field data from the conjugate Antarctic margin, well-expressed fracture zones can be traced throughout the Africa-Antarctica Corridor and allow the precise rotation of Antarctica back to Africa. The initial fit depicts striking continuations of onshore tectonic features across the plate boundaries taking onshore aeromagnetic data of both margins into account. Within a tight Gondwana fit, the Beira High can be restored along the major sinistral Namama-Orvin Shear Zone of the East African-Antarctic Orogen. The Beira High represents a continental block, which was detached from Antarctica, by 157 Ma at the latest. Simultaneously, the Antarctic plate cleared the area of the MCP. However, the crustal nature of the southern MCP remains ambiguous. The Northern Natal Valley and the Mozambique Ridge consist of thick oceanic crust, being emplaced between M26r-M18n (157.1-144 Ma) and M18n-M6n (144-131.7 Ma), respectively. About the half of this crust was won from the Antarctic plate by a series of southwards directed ridge jumps to the northern boundary of the Explora Wedge. A refined kinematic break-up model constrained by the most extensive magnetic dataset is presented describing consistently the initial opening of the Africa-Antarctica Corridor and the Somali Basin.
Year of Publication: 2019
Research Program: DSDP Deep Sea Drilling Project
ODP Ocean Drilling Program
Key Words: 18 Geophysics, Solid-Earth; 20 Geophysics, Applied; Africa-Antarctica Corridor; African Plate; Antarctic Plate; Beira High; Crust; DSDP Site 249; Deep Sea Drilling Project; Fracture zones; Geophysical methods; Geophysical surveys; Gondwana; Gravity methods; Indian Ocean; Leg 113; Leg 25; Lithosphere; Magnetic methods; Maud Rise; Mozambique Ridge; Natal Valley; ODP Site 690; Ocean Drilling Program; Oceanic crust; Oceanic lithosphere; Plate tectonics; Remote sensing; Rift zones; Rifting; Riiser-Larsen Sea; Satellite methods; Somali Basin; Southern Ocean; Surveys; Weddell Sea
Coordinates: S295700 S295659 E0360438 E0360437
S650938 S650937 E0011218 E0011218
Record ID: 2019019365
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands