新疆哈密东部早泥盆世生物地层研究

BIOSTRATIGRAPHIC STUDY ON THE EARLY DEVONIAN IN EASTERN HAMI,XINJIANG

新疆哈密东沁城一带出露一套以凝灰熔岩、凝灰岩、凝灰质灰岩为主的地层,厚度近600m。根据岩性特征,这套地层归入下泥盆统大南湖组。该剖面含丰富的腕足动物、较多三叶虫和小型单体四射珊瑚,另有少量床板珊瑚、腹足类、双壳类和海百合茎化石。经过对腕足动物、三叶虫等主要化石类群的研究,确认这套地层的时代为早泥盆世埃姆斯期(Emsian)。腕足动物化石的属种与东北北部、内蒙古东部、甘肃北山、新疆北部、蒙古、哈萨克斯坦等地的类型十分相似,说明早泥盆世晚期哈密与这些地区同属一个古生物地理分区——老世界大区的巴尔喀什—蒙古—鄂霍茨克区,与欧洲中部、北美和澳大利亚东部同类生物群有着比较密切的亲缘关系。

The Paleozoic strata are well-developed in the eastern part of North Tianshan and are mainly composed of volcanic clastic rocks. The Guanghui section is located about 20 km north of the Tula＇ergen Copper-Nickel Mine, Qincheng, eastern Hami, Xinjiang. Based on the underlying rocks, the strata are as- signed to the Lower Devonian Dananhu Formation. The fossils comprise brachiopods, trilobites, corals, gastropods, bivalves and crinoids. Brachiopods are the most abundant group near the top of the section and comprise 25 genera. Based on a study of the brachiopods and trilobites, the age of the strata in this section is determined as Emsian （Early Devonian）. The geographic distribution of the 25 genera of brachiopods shows that during Emsian times eastern Hami together with northeastern China, eastern Inner Mongolia and northern Xinjiang was part of the Balkhash-Okhotsk Biogeographic Province. The biota studied here show a close affinity to those in central Europe, eastern North America and Australia.