浙江淳安安吉组底部的几丁虫

CHITINOZOANS NEAR THE BASE OF THE ANJI FORMATION IN CHUN'AN COUNTY,ZHEJIANG PROVINCE

浙江淳安县大坑坞剖面安吉组底部化石丰富,其中腕足动物组合属于BA3中上部,指示正常浅海底域环境。作者通过分析该层位腕足化石标本的围岩发现一个低分异度的几丁虫组合,包含3属4种,即Ancyrochitina sp.,Belonechitina cf.postrobusta sensu Butcher,Belonechitina sp.,Spinachitina verniersi。该组合具有强烈的奥陶-志留纪过渡色彩,其时代可定为奥陶纪末期至志留纪初期。这是首次在该地区获得奥陶-志留纪过渡地层的几丁虫,有助于开展国际奥陶-志留系界线精细划分对比研究。文中描述了Belonechinacf.postrobusta和Spinachiti-naverniersi。

A chitinozoan assemblage of low abundance and low diversity is recovered near the base of the Anji Formation in western Zhejiang Province,East China.Belonechina cf.postrobusta and Spinachitina verniersi are recognized.Thus,a date of Latest Ordovician to Earliest Silurian is provided for the base of the Anji Formation where the chitinozoan assemblage is obtained.It is the first time that a chitinozoan assemblage across the Ordovician-Silurian boundary is recovered from South China,which may help improve our understanding of the chitinozoan distribution and refinement of subdivician and correlation of Ordovician-Silurian boundary strata in South China and elsewhere.The co-occurred brachiopod fauna is assigned to upper-middle BA 3（Benthic Assemblage）,indicating anormal shallow water condition.Two species,i.e.Belonechina cf.postrobusta and Spinachitina verniersi,are described.