新疆中天山汗吉尕组Helenifore robustum放射虫动物群及其年代地层学意义

HELENIFORE ROBUSTUM RADIOLARIAN FAUNA FROM THE HANJIGA FORMATION,MIDDLE TIANSHAN,XINJIANG,CHINA AND THE CHRONOSTRATIGRAPHIC SIGNIFICANCE

汗吉尕组是新疆中天山温泉小区中泥盆统的一个地层单元,为海相碎屑岩夹火山碎屑岩沉积。过去在灰岩团块和灰岩砾石中发现较为丰富的中泥盆世珊瑚和腕足类化石。这次,我们在该组上部地层硅质岩透镜体中首次发现晚泥盆世弗拉晚期的放射虫Helenifore robustum动物群。对于温泉地区该组地层的时代归属,我们认为:由于已发现的中泥盆世珊瑚、腕足类化石主要产于灰岩砾石或外来块体中,因此,这些化石的时代并不代表该组形成的时代;而产于硅质岩透镜体中的晚泥盆世弗拉晚期的放射虫化石很可能代表该组的年代。全文共描述放射虫5属11种,归属3目4科。

The Hanjiga Formation is a Devonian stratigraphic unit in Wenquan area of Middle Tianshan, Xinjiang, China which consists of marine clastic deposits with the intercalary of the volcanic clastic rocks. Rich Middle Devonian coral and brachiopod fossils have been found in the limestone lumps and gravels of this formation. Recently, the He- lenifore robusturn radiolarian fauna of late Frasnian, Irate Devonian, is discovered in the cherty lens of the upper Han jiga Formation. Therefore, regarding the age of the Hanjiga Formation, we suggest （1）because the Middle Devonian coral and brachiopod fossils were separately found in the limestone lumps and gravels in the Hanjiga Formation, they do not represent the age of the formation; （2） the late Devonian radiolarians reported herein most likely represent the age of the Hanjiga Formation, i. e. , late Frasnian. Five radiolarian genera and 11 species, belonging to 3 orders and 4 families, are described in this paper.