Information about how to find the excavation research in Case 03: In the Shadows - 3.2 - Chelsea Tunnel in Gotham Knights.
After your second encounter with Feral Talons you’ll eventually come across an excavation site, where you’ll need to investigate the area to find out what, exactly, the Court of Owls has been digging for.
Jump over a railing and turn left to find a wall marked with a grid pattern, helpfully labeled with a “CORE SAMPLE WALL” sign. Get close and use AR Tracking (hold the button) to scan some of the Sampling Drilling holes in the middle of the grid.
After you scan the core sample drilling holes, turn around and head to a lift. It’s inoperable, but easy enough to climb/grapple up to the top. When you do, note that there’s a table in front of you, and another room to the right. Head forward and scan the table in front of you to find some Ore Samples, nondescript cylinders that you’ll need to scan to increment the research counter.
Once done, return to the elevator and turn right to reach another room where you’ll find a table housing more Ore Samples for you to scan. You can also find a chest to the right of the table.
When you’ve scanned the core sample drilling holes and both ore samples on tables past the elevator, return to the elevator one last time and turn left to find a door leading deeper into the mines. This will lead to the Dionesium Extraction Investigation.