I think there may be a slight misunderstanding here.
Displacement currents DO NOT flow through the ground, but currents which are
considered to be flowing from the element, through the air dielectric back
to the earth. There they become considered conduction currents which flow
through the earth (and the radials) to the feed point. In the process, they
create "induce" other currents in the earth.
For some references (and diagrams} relating to displacement currents as they
pertain to vertical elements operating over earth, see "Antennas, Theory and
Practice" by Schelkunoff & Friis, John Wiley & Sons; "Electromagnetics" and
"Antennas", both by John Kraus, McGraw-Hill; "Radio Broadcast Ground
Systems" by Palmer Greer, Smith Electronics, Inc.; "Ground Systems as a
Factor in Antenna Efficiency", Brown/Lewis/Epstein (the original RCA/IRE
paper of 1937), and "Earth Conduction Effects in Transmission Systems" by
E.D. Sunde, Dover.
In addition, I'm sending you a diagram via email and will be glad to forward
to any others on the reflector upon email request.
73, Dave, K1FK
Fort Kent, ME