(Appendix) Calcium carbonate content in OD Hole 130-806B

Geochemical well logs were obtained in sediment at Sites 805 and 806 of Ocean Drilling Program Leg 130. Corrections have been applied to the logs to account for variations in bore-hole size, drilling-fluid composition, and drill-pipe attenuation. Oxide and calcium carbonate weight percentages were calculated from the logs and are compared with available carbonate measurements from core. Log-derived CaCO3 values from Hole 805C, though lower than shipboard CaCO3 core measurements, show a similar variation in character. In Hole 806B, log and shipboard CaCO3 sample values have a similar mean and variance. The CaCO3 high-resolution sample values from Hole 806B, however, have a similar mean but a lower variance than the CaCO3 logs. It is probable that discrepancies result from gamma-ray spectrometry tool malfunctions experienced throughout the logging operations of this leg as well as from chlorine-induced interference in the calcium yield. Because the amplitude of CaCO3 variations was extremely low (standard deviation of 1.38 on high-resolution samples), the tool, which has a sensitivity of roughly 2% for Ca, probably would not have been able to detect these variations, even if the tool had been working properly.