江西玉山早奥陶世笔石动物群的分带及分异

<正> 江西玉山具有完整的下奥陶统宁国组含笔石地层,陈旭、韩乃仁(1964)建立了下奥陶统笔石带,限于当时的标本采集,分带尚不够精确。1979年秋,笔者与邹西平、李罗照在玉山山头底(李家蓬)、会英亭、牟家坞等地测制剖面,获得了比较可靠的笔石分带。本文

Zonation and diversity of the Early Ordovician graptolite fauna of Yushan Jiangxi.

Seven Arenigian graptolite zones occur in Yushan, NE Jiangxi. In ascending order, they are Tet-ragrapius (Etagraptus) approximates Zone (Ni), Acrograptus filijormis Zone (N2), Didymograptus (Corymbograptus) deflexus Zone (Na), Azygograptus suecicus Zone (N4), Oncograptus Zone (N5), Car-diograptus amplus Zone (N6), and Glyptograptusaustrodentatus Zone (N7). Generally, the Pacific graptolite fauna is distributed in South China while the Yangtze graptolite fauna covers the Yangtze platform. These two graptolite faunas interfinger with each other in the transitional belt where the Yu-shan section is situated. Based on the Yushan section a precise age of the faunal differentiation was vertically determined by the first occurrence of the Pacific forms such as Graptoloid genus 1 Cooper, 1979 followed by the Oncograplus-Cardiograptus fauna. It indicates a faunal succession from the Yangtze fauna to the Pacific fauna. The Arenigian sea transgression brought the South china Pacific fauna Oncograptus and Cardiograptus onto the transitional belt where the Yangtze fauna (filiformis-snecicus fauna) was developed. Further sea transgression brought the Pacific austrode malm fauna through the transitional belt onto the Yangtze platform.