滇东北昭通箐门的泥盆纪珊瑚(三)——晚泥盆世早期的四射珊瑚

DEVONIAN CORALS FROM ZHAOTONG,NE YUNNAN (3)——EARLY FRASNIAN RUGOSE CORALS

云南昭通市东北郊箐门出露了一条比较完整的泥盆纪浅海相地层剖面,下、中、上三个统均有出露,浅海底栖生物化石丰富,研究基础也相对较好,是研究滇东北地区泥盆纪地层的一条理想剖面。由于地层剖面比较长,沉积厚度比较大,此前笔者已经描述了早泥盆世和中泥盆世的四射珊瑚,本文继续描述该剖面的晚泥盆世的地层及其四射珊瑚,讨论它们的地层划分、珊瑚群对比与古生物地理。昭通箐门剖面的上泥盆统主要由白云质灰岩组成,与滇东其它地方的宰格组的岩性基本一致。过去由于宰格组的化石稀少,其地层时代难于确定,因此,昭通箐门宰格组底部珊瑚化石的发现具有重要意义。文中首次描述了箐门放羊冲剖面宰格组底部的四射珊瑚5属7种,包括Disphyllum catenatum,Hexagonaria davidsoni,H.magna,Sinodisphyllum simplex,S.variabile,Temnophyllum poshiense和Truncicarinulum temeniophylloides等,总体显示了晚泥盆世弗拉早期(early Frasnian)的特点。它除了与华南各省的珊瑚群有密切关系外,也与加拿大西部的分子有一定的联系。

A relatively complete and thick lower through upper Devonian shallow marine sequence crops out in the vicinity of Qingmen Village in the suburb of Zhaotong, NE Yunnan Province, which yields abundant shallow water benthic fossils. The Qingmen section（including Fangyangchong）has become a reference Devonian section in the NE Yunnan due to its well established stratigraphic succession.Nevertheless,rugose corals have not been described until recently.The present paper is the third of the series of rugose corals studies,dealing with early Frasnian strata and rugose corals, with discussions on lithostratigraphy,correlation of coral faunas and their palaeobiogeography. The Upper Devonian sequence at Qingmen（Fangyangchong） is lithologically consistent with the Zaige Formation.This formation is mainly composed of dolomitic limestones and bears very few fossils.So that its geological age is not readily determined.Hence,the description and illustration of the rugose coral fauna from the base of the Zaige Formation of Qingmen（Fangyangchong）is of some importance.This fauna is composed of five genera and seven species,including Sinodisphyllum simplex,S.variabile,Disphyllum catenatum,Hexagonaria magna,H.davidsoni,Temnophyllum poshiense and Truncicarinulum temeniophylloides. These rugose corals overall suggest an early Frasnian age and a close biogeographic relationship between South China and western Canada.the description and illustration of the rugose coral fauna from the base of the Zaige Formation of Qingmen（Fangyangchong）is of some importance.This fauna is composed of five genera and seven species,including Sinodisphyllum simplex,S.variabile,Disphyllum catenatum,Hexagonaria magna,H.davidsoni,Temnophyllum poshiense and Truncicarinulum temeniophylloides. These rugose corals overall suggest an early Frasnian age and a close biogeographic relationship between South China and western Canada.