The Dutchman was carried off and covered in a blanket, sparking fears that he had broken his leg. Whilst the actual injury is less than feared, Cas will still be sorely missed.
"Marcel has got quite bad gashes on both legs," manager Paul Groves told the Grimsby Telegraph. "He had to go hospital and they took him into theatre.
"It was quite a collision. He got to the ball first but the impact spun him round back towards his own goal.
"He's been told two weeks but we will see how that goes."
The injury to Cas means Graham Hockless is likely to start against Blackpool on the left wing with Stuart Campbell moving across to the right flank.