臭牛沟组命名剖面(竹蜓)类的发现

Discovery of fusulinids from the typical section of the Chonukou Formation

臭牛沟组的命名剖面地点,位于甘肃武威西南35km的臭牛沟河北岸,现属甘肃天祝藏族自治县祁连乡管辖。据袁复礼研究,臭牛沟组不整合于早古生代南山系变质岩之上,其上为上石炭统假整合覆盖。袁氏将臭牛沟组粗略划分为四层,由下而上为,1.石英岩和砂岩(50m),2.砂岩和页岩,底部页岩产植物化石(12m),3.砂岩和页岩,未获化石(5m),4.灰岩和页岩,富含化石(68m)。袁氏在层4中采集的大批海相动物化石。

The Choniukou Formation yielding Gigantoproductus, Kansuella and Yuanophyllum used to be considered as a standard lithostratigraphic unit of the Late Visean in China. A new discovery of the fusulinid fauna from the typical section of this formation resulted in the conclusion that the middle and upper parts of this formation, where the fusulinds were found, were deposited during the Namurian time. Two fusulinid biozones, the Namurian A Eostaffella hohsienica-E. mosquensis Zone below and the Namurian B-C Millerella marble-nsis-Eostaf fella postmosquensis Zone above, are established in this paper. The lower part of this formation appears to belong to the late Visean due to the existence of a florule with Visean aspect. The Mid-Carboniferous boundary in this formation is between the middle and upper parts based on the first appearance of both Millerella marblensis and M. pressa.