There are several treasure chests and sealed caves throughout Argus’ zones (Krokuun, Mac’Aree, and the Antoran Wastes). The treasure chests are either inaccessible due to a force field, or inside caves blocked by a pile of rocks. These two have something in common: both have a floating crystal marking them.
As of PTR patch build 7.3 v0.24781 we now know their purpose: “Will only open to one wielding the power that echoes that of the Augari.”
According to Marcel Neubert (in the comments) these are opened with the Vindicaar abilities. The color of the crystals match the Vindicaar abilities. For example:
The images below show some of the treasure chests and blocked caves (with coordinates) that can be unlocked once you acquire the power of the Augari.
TREASURE CHESTS MAP
These are the treasure chests I have found so far marked in the maps below. All treasure chests respawn in less than 24 hours. You won’t find the ones marked as grey circles 100% of the time at the same location because they respawn at a random location. The grey circles are merely coordinates where I have personally sighted a normal treasure chest. Submit more via private message @blizzplanetcom
For larger images hold down the right-button and choose “Open Link in New Tab.”
In the Mac’Aree map (above) there are two marked with the Goblin Glider icon. These two treasure chests can be reached via Goblin Glider or the Demon Hunter glide ability.