GENESIS OF PODZOLS ON COASTAL DUNES IN SOUTHERN QUEENSLAND - V - CHEMISTRY AND MINERALOGY OF THE NON-OPAQUE HEAVY MINERAL FRACTION

Eight podzols on coastal dunes from the Cooloola chronosequence, and a n associated pedon from North Stradbroke Island (Amity), were studied to establish (i) the degree of homogeneity of the parent material betw een and within profiles, (ii) the extent of heavy mineral weathering, and (iii) whether the parent sediments of each pedon had a common prox imate source. The pedons are Quartzipsamments and Troporthods with age s ranging from Holocene to Pleistocene. On the basis of ratios zircon: rutile, zirconium:titanium, and non-magnetic:very magnetic heavy miner als in the fine sand fraction (53-125 mu m), we concluded that the par ent materials of the Cooloola pedons were mineralogically similar. By using zirconium in the non magnetic heavy mineral fraction as an index for zircon, it is evident that there has been considerable pedogeneti c weathering of the heavy mineral fraction. There is a statistically i nsignificant difference in hafnium concentrations of zircons which imp lies that parent sediments of the soils at Cooloola and North Stradbro ke Island were derived from a common immediate source.