Paleogeographic maps of the continents bordering the Indian Ocean since the Early Jurassic

Abstract

Paleomagnetic data from the African plate from the Early Jurassic onward are critically re‐evaluated and updated, resulting in a set of 30 paleopoles, from which an apparent polar wander path is derived using 20 Ma intervals. This path is then used, in conjunction with kinematic models of the Indian and Atlantic oceans, to place other continents bordering the Indian Ocean (Eurasia, India), islands and plateaus (Madagascar, Seychelles‐Mascaréne), and blocks involved in the collision of India with Eurasia (south Tibet, Indochina) in an “absolute” paleogeographic frame fixed with respect to Africa. Paleogeographic maps are presented for the Early Jurassic (pre‐breakup), the Jurassic‐Cretaceous boundary (anomaly Ml5), the Early Cretaceous (M2), the Late Cretaceous (A 34), the Cretaceous‐Tertiary boundary (A 29), the Early Eocene (A 24), the middle Eocene (A 21) and the Oligocene‐Miocene boundary (A 6). Observed and predicted paleomagnetic directions for landmasses other than Africa (i.e., for western Europe, China, Korea, India, and Australia, which are not used in deriving the maps) are found to be in very satisfactory agreement. The quality of reconstructions, as measured by rms discrepancies between observed and predicted paleolatitudes, is of the order of 5°. The main features of the paleogeographic maps are discussed, with the aim of relating oceanic and on‐land geodynamic events. The constraints provided by Tibetan data on the India‐Asia collision, and the 20 Ma reorganization of geology and plate boundaries in a band extending from the south China Sea, through Tibet, to the Red Sea system are discussed in more detail. We emphasize the episodic nature of the breakup of Gondwanaland and formation of the Indian Ocean, and subsequent interaction with Eurasia, in which six major discrete events are identified, separated by ∼30 Ma phases of rather uniform plate motion.