Analysis of ancient sediments for total organic carbon - some new ideas

Abstract

It has recently been noted that significant interlaboratory variation exists with regard to total organic carbon (TOC) values. The problem of interlaboratory variation appears to be due to differences in equipment, standards, and methodology. In response to this apparent problem a new total organic carbon analyzer has recently been developed by the authors. The new system utilizes a Lindberg quartz tube furnace set at 800°C, which provides a rapid and complete combustion without the need for accelerators. The amount of CO 2 produced by the sample is detected using a Beckman non-dispersive infrared analyzer, selective for CO 2. The system is calibrated using carbon standards developed by the authors and has an expected range from 0.01 to 20% TOC. The validity and reproducibility of the tube furnace system results were tested thoroughly by combusting numerous “in-house” standards. The mean values compare favourably with those obtained from the independent analyses and are believed to be accurate to within 5%. TOC values obtained from the system, combined with other geochemical and geophysical signatures, were successfully used to define the extent of the Collingwood Member of the Lindsay Formation, in the subsurface of southwestern Ontario, using well cuttings and core. It is forseen that the main use of this system will be in oil shale and hydrocarbon source bed evaluation, but an application also lies in the exploration for ore bodies associated with organic deposits.