Motion between the Indian, Antarctic and African plates in the early Cenozoic

• Published in: Geophysical Journal International
• Main Authors: Cande, Steven, C, Patriat, Philippe, Dyment, Jerome
• Other Authors: Scripps Institution of Oceanography (SIO - UC San Diego), University of California San Diego (UC San Diego), University of California (UC)-University of California (UC), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2010
• Subjects: Indian Ocean C; Kinematics of crustal and mantle deformation; Plate motions; [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; Antarctic; Bain; Bain Fracture Zone; Indian; Southeast Indian Ridge; Antarc*
• Online Access: https://insu.hal.science/insu-01309198; https://insu.hal.science/insu-01309198/document; https://insu.hal.science/insu-01309198/file/Geophys.%20J.%20Int.-2010-Cande-127-49.pdf; https://doi.org/10.1111/j.1365-246X.2010.04737.x

International audience We used a three-plate best-fit algorithm to calculate four sets of Euler rotations for motion between the India (Capricorn), Africa (Somali) and Antarctic plates for 14 time intervals in the early Cenozoic. Each set of rotations had a different combination of data constraints. The first set of rotations used a basic set of magnetic anomaly picks on the Central Indian Ridge (CIR), Southeast Indian Ridge (SEIR) and Southwest Indian Ridge (SWIR) and fracture zone constraints on the CIR and SEIR, but did not incorporate data from the Carlsberg Ridge and did not use fracture zones on the SWIR. The second set added fracture zone constraints from the region of the Bain fracture zone on the SWIR which were dated with synthetic flowlines based on the first data set. The third set of rotations used the basic constraints from the first rotation set and added data from the Carlsberg Ridge. The fourth set of rotations combined both the SWIR fracture zone constraints and the Carlsberg Ridge constraints. Data on the Indian Plate side of the Carlsberg Ridge (Arabian Basin) were rotated to the Capricorn Plate before being included in the constraints. Plate trajectories and spreading rate histories for the CIR and SWIR based on the new rotations document the major early Cenozoic changes in plate motion. On the CIR and SEIR there was a large but gradual slowdown starting around Chron 23o (51.9 Ma) and continuing until Chron 21y (45.3 Ma) followed 2 or 3 Myr later by an abrupt change in spreading azimuth which started around Chron 20o (42.8) Ma and which was completed by Chron 20y (41.5 Ma). No change in spreading rate accompanied the abrupt change in spreading direction. On the SWIR there was a continuous increase in spreading rates between Chrons 23o and 20o and large changes in azimuth around Chrons 24 and 23 and again at Chron 21. Unexpectedly, we found that the two sets of rotations constrained by the Carlsberg Ridge data diverged from the other two sets of rotations prior to anomaly 22o. When compared ...