>Has anyone out there done work on c-isotope analysis on organic
>carbon in ancient sediments?

A LOT, ranging from Holocene to Cretaceous.  I'm at sea so I don't have
specific rteferencers before me, but see Dean, Arthur, and Claypool, Marine
Geology, 1986; Dean, Gardner, and Anderson, Paleoceanography, Jan. 1994.


 My question is this; in programmed
>pyrolysis (Rock-Eval), samples with a %TOC value less than 2% give
>questionable results due to matrix effects from clays,

ok at least to 1% TOC  Try usi ng S1+S2 rather than H-index.  Forget O-index.


Walt Dean
USGS Denver, CO  USA

Walter E. Dean
       RV Ewing
      Somewhere in the
        Northeast Pacific