Linq expression to set all values of an array to a given value

I have a bit of code that i'd like to turn into a linq expression (preferably with lambdas) to make it easier to use as a delegate. The code looks like this:

List<DateTime[]> changes = new List<DateTime[]>();
changes = PopulateChanges();
for (int i = 0; i < changes.Count; i++)
{
    for(int j = 0; j < changes[i].Length; j++)
    {
        changes[i][j] = DateTime.MinValue;
    }
}

For the life of me, I can't seem to figure this one out. I've tried using ForEach and various forms of select, etc.. nothing seems to work right.

FYI, I know that DateTime defaults to MinValue, in reality this is clearing the arrays to default after they've already been set.

Can anyone help me with a working expression?

EDIT:

I guess what I'm really saying here is I want a concise way to set all elements of a multi-dimensional array to a given value. Certainly, the nested for loop works, and I can certainly place it in a function (which I have already done). I just want something more concise that can be used more easily in a delegate without creating a multi-line monster.