From CSS Display,

The element generates a principal table wrapper box containing an additionally-generated table box, and establishes a table formatting context.

It's not much clear if what establishes the TFC is the table wrapper box. The sentence sounds like it's the element, but I believe formatting contexts established in the box tree, not the element tree. So probably it's the table wrapper box or the table box.

CSS Tables 3 and CSS 2.1 are more clear:

The table wrapper box establishes a block formatting context.

I think this means that both the table box and the caption participate in a BFC.

However, CSS Display says

table-row-group, table-header-group, table-footer-group, table-row, table-cell, table-column-group, table-column, table-caption
The element is an internal table element, and participates in a table layout context.

Which is it, does the caption participate in a BFC or in a TFC? What establishes the TFC, the table wrapper box or the table box?

Since captions can't exist outside a table wrapper box (they generate an anonymous one if necessary), I think they should participate in a TFC, which would be established by the table wrapper box.