Sharingan sealing jutsu
It is common knowledge that the Sharingan is multi-faceted, versed in the 3 ninpo. We've seen this from Itachi transferring ocular powers with the touch of a finger:
And the Totsuka no Tsurugi carried by the Susanoo:
However, this chapter is the first time I've seen a physical seal that can only be triggered by a Sharingan. I initially thought nothing of the levitating uchiha stone, and that Orochimaru might have done it. However, I recalled the gibberish that Kishimoto writes as sealing formulas, such as on summoning jutsu:
The sealing stone that blocks the Uchiha basement, carries a sealing formula, with a Sharingan in the center. It seems not be the case with what Itachi did, where something triggers at the presence of a Sharingan; there's an additional step. This apparently explains why Sasuke had his Sharingan activated at the time, and seemed to be making a handseal.