Aluminum, Titanium and Vanadium in Recent and Fossil Shells

Abstract

To study the behaviors of trace elements in shells during the process of fossilization, alumihum, titaRium and vanadium, containing in shells belonging to Pelecypoda colleeted from Miocene, Pliocene, Pleistocene and Recent deposits in the northeastern Japan, were determined by nondestructive neutron activation analysis.The samples were irradiated in the TRIGA Mark ff Reactor of Rikkyo University (thermal neutron flux5*10ii n/cm2/sec)for 3 min. After coo1ing for 3 min, r-rays of 2sAl, Ti and S2V were measured, for 5 min using a 4096 channelGEOSCIENCE pulse height analyzer and a ORTEC Ge(Li) detector (effective volume 50ml).The contents of aluminum, titanium and vanadium in Recpnt she11s havebeen found to correlate with the crystal-form of calcium carbonater and the shestructure: each content of the three elements in calcite type shells with foliated structure was higher than that in aragonite type shells and calcite type shells with homogeneous or complex prismatic structure.Although the contents of aluminum, titanium and vanadium in fossil shells generally increased with increasing age contrary to the decrease in residual organic matters in shells, the pattern and the degree of increase changed with variation of the shell structure and the crystal-form of calci um carbona.te. Q, n the other hand, the V/Al ratio of fessil shells seemed to increase in Proportion to that of the environmental sediments, These results suggested that, aluminum, titanium and vanadium in fossil shells were supplied from the surrounding sediments during the progress of fossilization.