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 three distinct types of proxy environmental record; long-term (years to decades), annual and short-term or ''pulse'' records. Long-term records are not likely to be affected by skeletal growth mechanisms because these mechanisms operate at annual or shorter time scales. However, annual and pulse records will be affected by annual cycles in skeletal density 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 examine the effect of growth mechanisms upon pulse inclusions. The results suggest that useful proxy records can be recovered by optical measurements of lines which can be seen, or which can be made visible, in a section sawn along a skeletal growth axis. The results suggest that it will be difficult to recover records of pulse events from measurements of the concentration of trace material in the skeleton. Overall, the results reinforce recent suggestions that understanding of coral skeletal growth mechanisms is fundamental to recovery of reliable proxy environmental records from massive corals.