da97a51a_d_Questions___Chase_Paymentech__Explanation
[Statement Section] Chargebacks & Reversals (Red) Black [Explanation] 
Chargebacks are "charged back to the merchant" meaning they were initiated to get money back for the customer from the merchant and reversals are, by definition, reversing the chargeback and giving the money back to the merchant. Therefore, a credit to the merchant account is black and a debit is red.
Merchant Statements Frequently Asked Questions | Chase Paymentech
Explanation