The Capricorn plate is a hypothesised minor tectonic entity beneath the Indian Ocean basin (southern–eastern hemispheres) whose formal recognition remains unresolved. It is interpreted as a relatively coherent block of oceanic lithosphere occupying the far western margin of the erstwhile Indo‑Australian plate; in this view Capricorn behaves in many respects like a discrete plate distinct from adjacent lithospheric domains.
Tectonic reconstructions indicate that Capricorn was formerly integrated with India and Australia within a single Indo‑Australian plate. Neogene rifting initiated separation of the Capricorn block from its Indian and Australian neighbours, with onset estimates commonly placed between ~18 and 8 Ma. Separation appears to have occurred through distributed deformation across a broad zone rather than along a single narrow fault.
The inferred Capricorn boundary is therefore wide and diffuse, exemplifying a class of plate junctions that are spatially distributed over tens to hundreds of kilometres. This pattern departs from the mid‑20th‑century paradigm of rigid plates bounded by narrow faults and illustrates how internal, spatially extended deformation can subdivide a previously unified plate.
Read more Government Exam Guru
Recognising the Capricorn block and its diffuse margins bears directly on palaeogeographic reconstructions, the partitioning of regional stress and strain, and assessments of seismic hazard in the Indian Ocean realm. Confirmation of its existence, boundary geometry, kinematics and timing of separation requires additional integrated geophysical and geological investigations.