The Riven Gate is the checkpoint that blocks you during the mission titled The Sequence. This area is filled with enemies, but it also has a bunch of collectibles. In total, there are five collectibles hidden in the Riven Gate checkpoint in Halo Infinite. Here is where you can find them.
After you have completed the mission Pelican Down, you will be taken to the southeast corner of the map. The Riven Gate is to the west of where you land and it blocks the only road that travels to the west. Take a look at the map above for reference if needed.
The first collectibles you can find are the Banished audio logs. There are two in this location. The first Banished audio log is located in the building with the Banshee. Get inside the building by activating the podium in the tower nearby. Once inside, go to the back wall to find the audio log.
For the second Banished audio log, you will need to wait until you have progressed through the mission at the Riven Gate a bit. After getting the doors unlocked, you will need to go up to one of the nearby cliffs to locate the power source. The audio log is in the building before you enter the room with the hologram map.
The Spartan Core is up next. You can find this collectible in the same area as the second Banished audio log. Before you can access the Spartan Core, you will need to disable to shield protecting it. Have The Weapon interact with the console in the room to expose the generator. Destroy it and you will be able to access the Spartan Core.
The first of the two UNSC audio logs can be found on the cliffs in the northern section of Riven Gate. From the eastern side where you will most likely first enter Riven Gate, head to the western gate, and climb the cliffs above the gravity launcher. You will find the audio log near some UNSC equipment.
The second UNSC audio log can be found outside of the checkpoint. Head to the eastern side of the checkpoint and climb the mountains just outside of the gate. You will find a small sniper post with the audio log resting on the cliff.