▁within ▁the ▁mant le . ▁As ▁the ▁mant le ▁is ▁ins ulated ▁by ▁the ▁thick ▁sub cont inental ▁cr ust , ▁heat ▁accum ul ates ▁and ▁mant le ▁temperature ▁under ne ath ▁the ▁cr ust ▁increases . ▁Hence ▁the ▁temperature ▁gradient ▁between ▁the ▁mant le ▁near ▁core ▁and ▁l ith os phere ▁decre ases , ▁and ▁con ve ction ▁cannot ▁be ▁sust ained . ▁The ▁high ▁temperature ▁in ▁the ▁l ith os phere ▁causes ▁cr ust al ▁thin ning ▁and ▁intr us ions . ▁ ▁In ▁addition , ▁sub du ction ▁zones ▁present ▁due ▁to ▁the ▁movement ▁of ▁G ond w ana ▁contin ental ▁fragments ▁further ▁influence ▁the ▁con ve ction ▁of ▁mant le . ▁Therefore , ▁in hom ogeneous ▁mant le ▁is ▁formed ▁and ▁causes ▁cr ust al ▁thin ning . ▁Vari ous ▁ igne ous ▁structures ▁formed ▁by ▁mag ma ▁intr usion ▁from ▁the ▁mant le ▁to ▁cr ust ▁and ▁extr usion ▁to ▁the ▁land ▁surface . ▁ ▁Sign ific ance ▁The ▁Ok av ango ▁dy ke ▁sw arm ▁acts ▁as ▁a ▁kin ematic ▁indicator ▁for ▁the ▁Jur ass ic ▁evolution ▁of ▁Kar oo ▁Lar ge ▁Ig ne ous ▁Province ▁related ▁to ▁the ▁fragment ation ▁of ▁G ond w ana ▁super cont inent , ▁as ▁it ▁records ▁the ▁pale o - str ess ▁and ▁stra in . ▁ ▁The ▁significant ▁geometry ▁of ▁the ▁Kar oo ▁triple ▁j unction ▁formed ▁by ▁the ▁giant ▁dy ke ▁sw ar ms ▁can ▁be ▁used ▁to ▁identify ▁the ▁site ▁of ▁a ▁mant le ▁pl ume ▁or