Join two string lists elements one by one

Question

I have two IEnumerable<string> that I need to combine joining their elements "index by index".

At the moment I'm using a simple foreach statement to merge the elements one by one and add them to a List<string>.

List<string> res = new List<string>();
int index = 0;
foreach (var date in dates)
    res.Add(
        string.Join(
            ",", 
            DateTimeOffset.FromUnixTimeSeconds(long.Parse(date)).ToString("yyyy-MM-dd HH:mm:ss"), 
            values.ElementAt(index++)
            )
        );

I was wondering if there is a way to solve this directly in LINQ.