ON THE INCLUSION OF TRACE MATERIALS INTO MASSIVE CORAL SKELETONS .1. MATERIALS OCCURRING IN THE ENVIRONMENT IN SHORT PULSES

Trace materials included in coral skeletons during growth provide thre e distinct types of proxy environmental record; long-term (years to de cades), annual and short-term or ''pulse'' records. Long-term records are not likely to be affected by skeletal growth mechanisms because th ese mechanisms operate at annual or shorter time scales. However, annu al and pulse records will be affected by annual cycles in skeletal den sity and extension rate, and by mechanisms which control the time and position in which new skeleton is added. Numerical models of skeletal growth in Porites (Taylor et al., 1993) are extended and used to exami ne the effect of growth mechanisms upon pulse inclusions. The results suggest that useful proxy records can be recovered by optical measurem ents of lines which can be seen, or which can be made visible, in a se ction sawn along a skeletal growth axis. The results suggest that it w ill be difficult to recover records of pulse events from measurements of the concentration of trace material in the skeleton. Overall, the r esults reinforce recent suggestions that understanding of coral skelet al growth mechanisms is fundamental to recovery of reliable proxy envi ronmental records from massive corals.