Abstract:

This paper is based on the compilation of the Indian Ocean Tectonic Map and the analyses of the tectonic pattern and
significant tectonic events of Indian Ocean. Three problems are further discussed concerning the initial breakup mechanism of Indian
Ocean, ridge jump and hotspots, and mid-ocean ridge extension. We draw the following conclusions: 1) The Indian mid-ocean ridges
can be divided into two systems: Southeast Indian Ridge-central Indian Ridge-Carlsberg Ridge (East Branch), and Southwest Indian
Ridge (West Branch). The former system is the product of Pacific Ocean Ridge system extension. The latter one is the product of the
tectonic adjustment of Pacific-Southeast Indian Ridge system and Atlantic Ocean ridge system. 2) The initial breakup was controlled by
vertical compression-horizontal extension and developed along pre-Cambrian orogen. 3) Indian Ocean experienced two major ridge
jump processes. The directions of ridge jump and hotspot movement are consistent, illustrating internal connection of the two tectonic
processes. 4) The Atlantic and Pacific mid-ocean ridge systems joined in Indian Ocean in Paleogene. Its terminal was continuously
fragmented. This can be called Fish-Tail Tectonics, which illustrates that Indian Ocean links up and adjusts the development of three
major ocean basins. The Indian Ocean is therefore a key hinge of global oceanic basins.

Key words: Indian Ocean, sea floor spreading, ridge jump, ridge extension, hotspot, tectonic pattern, tectonic evolution, Fish-Tail Tectonics