Quarantine zone (location)
From Halopedia, the Halo wiki
Summary
The Quarantine Zone is a perimeter established by the Covenant upon their landing on Installation 05. The Quarantine Zone is directly outside the Delta Halo Library's Shield Wall. The Containment Shield Wall has kept much of the Flood from spreading, but once the Shield Wall was deactivated by the Arbiter during his search for the Sacred Icon, the Flood could move more freely about the ring.
