いくつかの底生有孔虫種の殻成長終末期における殻重量の変化

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概要

• 論文の詳細を見る

• The purpose of this study is firstly to investigate the growth stage of shell at which the replenishment of earlier chambers and the crust formation occur in connection with some benthic foraminiferal species and secondaly to clarify its taphonomical significance. When the replenishment and the forming of crust occur, shell weight is increased, rapidly. In consequence of this the settling velocity of shells in still water is accelerated Foraminiferal shells are placed in still water with sediment particles using the emery-typed tube and settled material are cut into nine samples according to the order of their settlement, and the size of shells is compared with that of quartz spheres settled during the same time periods. In most of the species studied, the relative rate of increase in weight per surface area of shells is larger than that of quartz spheres in the stage of smaller shell size, but in the stage of larger shell size it shows the inverse relationship. In other words, a change of the relative rate of shell mentioned above takes place abruptly at certain growth stage. It does in the sample in which the largest numbers of individual occurs or in the sample in which the individual numbers decrease abruptly in the coaser grained samples as opposed to that sample. On the other hand, the shell form change of each foraminiferal species is not observed so distinctly through all the growth stages. These facts indicate that the shell weight of most species of investigated foraminifers becomes heavy abruptly by the replenishment of earlier chambers and/or the forming of crust after coming into the various type of full-growth stage of each species. The phenomenon of this sort is widely known regarding marine benthos with calcareous shell such as bivalves. This suggests a need of particular consideration in using size-frequency data in the taphonomical analysis of benthic foraminifers.

• 地学団体研究会の論文
• 1979-11-25

著者

• 亀山 徳彦

  北九州大学文学部

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