ues ▁Tri ple ▁J unction ▁( RT J ), ▁also ▁known ▁as ▁the ▁Central ▁Indian ▁[ O cean ] ▁Tri ple ▁J unction ▁( C IT J ) ▁is ▁a ▁ge olog ic ▁triple ▁j unction ▁in ▁the ▁southern ▁Indian ▁Ocean ▁where ▁three ▁t ect onic ▁pl ates ▁meet : ▁the ▁African ▁Pl ate , ▁the ▁Ind o - Austral ian ▁Pl ate , ▁and ▁the ▁Ant ar ctic ▁Pl ate . ▁ ▁The ▁triple ▁j unction ▁is ▁named ▁for ▁the ▁island ▁of ▁Rod rig ues ▁which ▁lies ▁ ▁north - west ▁of ▁it . ▁ ▁The ▁R T J ▁was ▁first ▁recognized ▁in ▁ 1 9 7 1 , ▁then ▁described ▁as ▁a ▁stable ▁R - R - R ▁( ridge - ridge - ridge ) ▁triple ▁j unction ▁based ▁on ▁co arse ▁ship ▁data . ▁ ▁B ound aries ▁The ▁boundaries ▁of ▁the ▁three ▁pl ates ▁which ▁meet ▁at ▁the ▁Rod rig ues ▁Tri ple ▁J unction ▁are ▁all ▁ocean ic ▁spread ing ▁cent ers , ▁making ▁it ▁an ▁R - R - R ▁type ▁triple ▁j unction . ▁ ▁They ▁are : ▁the ▁Central ▁Indian ▁R idge ▁( C IR , ▁between ▁the ▁African ▁and ▁Ind o - Austral ian ▁pl ates ) ▁with ▁a ▁spread ing ▁rate ▁of ▁ 5 0   mm / yr ; ▁the ▁South west ▁Indian ▁R idge ▁( SW IR , ▁between ▁the ▁African ▁and ▁Ant ar ctic ▁pl ates ) ▁ 1 6   mm / yr ; ▁and ▁the ▁S out heast