Distribution of Recent benthic foraminifers in the interstitial waters with high methane and hydrogen sulfide contents

本文讨论了晚新生代底栖有孔虫组合与具有冷渗流的化学古环境的关系。采用q型因子分析方法对三浦半岛和Kakegawa地区分布的与晚新生代冷渗流有关的特殊软体动物组合与底栖有孔虫组合进行了研究。分析结果揭示了以下化学因素和底栖有孔虫与软体动物类群之间的关系：(1)影响底栖有孔虫分布的化学因子有基质水和底水的硫化氢含量、甲烷含量、溶解氧和碱度；(2)在Calyptogena组合中共出现了Bulimina aculeata、Bulimina striata、Hyalinea balthica和Nonionellina labradorica；(3)在Lucinoma组合中共出现了Rectoboliviana columellaris和Uvigerina proboscidea；在产生Acharax组合的样品中，Rectoboliviana cf.asanoi和Stilostomella lepidula占主导地位。

This report discusses the relationship between the benthic foraminiferal assemblages and the chemical paleoenvironments with the cold seepage during the Late Cenozoic time. Benthic foraminiferal assemblages co-occurred with the peculiar molluscan assemblages, which were related with the Late Cenozoic cold seepage and were distributed in Miura Peninsula and the Kakegawa area, are examined by means of Q-mode factor analysis. The results of this analysis reveal the following chemically factors and the relationship between benthic foraminifers and molluscan taxa : (1) the chemical factors, which influences to the distribution of benthic foraminifers, are the hydrogen sulfide contents, methane contents, dissolved oxygen and alkalinity of the interstitial and bottom waters, (2) Bulimina aculeata, Bulimina striata, Hyalinea balthica and Nonionellina labradorica co-occur from the Calyptogena assemblage, (3) Rectoboliviana columellaris and Uvigerina proboscidea are found together with the Lucinoma assemblage, and (4) Nodosaria longiscata, Rectoboliviana cf.asanoi and Stilostomella lepidula are dominated in the samples yielding the Acharax assemblage.