▁may ▁not ▁be ▁compatible ▁with ▁the ▁hypothesis , ▁due ▁to ▁the ▁following ▁reasons : ▁Kar oo ▁mag mat ism ▁last ed ▁from ▁ 1 8 3 – 1 7 4 ▁Ma ▁which ▁is ▁almost ▁twice ▁the ▁duration ▁of ▁a ▁normal ▁active ▁mag ma ▁pl ume . ▁Later al ▁intr ud ing ▁mel ts ▁from ▁the ▁Kar oo ▁triple ▁j unction ▁are ▁observed ▁at ▁the ▁Ok av ango ▁Dy ke ▁Sw arm , ▁which ▁shows ▁that ▁it ▁is ▁not ▁fed ▁by ▁a ▁deep ▁mag ma ▁pl ume ▁but ▁instead ▁from ▁a ▁shall ow ▁mag ma ▁source . ▁ ▁The ▁sub - parallel ▁Pro ter oz o ic ▁dy kes ▁in ▁the ▁Ok av ango ▁Dy ke ▁Sw arm ▁are ▁the ▁age ▁constraint ▁for ▁the ▁mag ma ▁pl ume ▁hypothesis . ▁The ▁Pro ter oz o ic ▁dy kes ▁have ▁an ▁age ▁of ▁over ▁ 8 0 0 Ma . ▁But ▁Kar oo ▁mag mat ism ▁occurred ▁at ▁around ▁ 1 8 0 Ma . ▁ ▁Model ▁ 3 : ▁Pass ive ▁mel ting ▁of ▁G ond w ana ▁super cont inent ▁Another ▁hypothesis ▁of ▁the ▁Kar oo ▁Lar ge ▁Ig ne ous ▁Province ▁( which ▁includes ▁the ▁Ok av ango ▁Dy ke ▁Sw arm ) ▁is ▁the ▁lack ▁of ▁cool ing ▁within ▁the ▁mant le . ▁ ▁The ▁lack ▁of ▁movement ▁of ▁the ▁G ond w ana ▁super cont inent ▁creates ▁ins ulating ▁effect ▁to ▁the ▁sub - cont inental ▁mant le . ▁It ▁may ▁create ▁significant ▁impact ▁to ▁con ve ction ▁and ▁temperature