Dynamic WPF 3D Textures

I am writing a program (C # .NET 4.0 WPF 3D) that displays slices of the earth (for example, the OpendTect or Petrel seismic module).

The problem is that I need to be able to deeply magnify and still see the details.

I tried to put a huge detailed texture (5000x5000), but it eats too much memory (200-300 MB) and crashes when I try to increase the size.

Now I want to see if there is a way to use something like a dynamic texture - one that will change depending on the distance to the camera.

Or maybe there is some other way to work with high-resolution surfaces?

I use this code to load the texture:

wbm = new WriteableBitmap(
(int)1306*scale,
(int)ns*scale,
96,
96,
PixelFormats.Indexed8,
new BitmapPalette(getColors()));

...

visual3d.Material = visual3d.BackMaterial
= new DiffuseMaterial(new ImageBrush(wbm));