新疆色帕巴衣地区志留纪柯坪塔格组笔石的发现

The discovery of Silurian graptolites from the Kepingtage Formation in Sepabayi area, Xinjiang

新疆色帕巴衣地区志留纪柯坪塔格组岩性以片理化泥岩和中厚层长石石英细砂岩为主,生物化石较少,缺少时代依据。该地区柯坪塔格组中段底部泥岩中首次发现保存完好的笔石化石,计有5属5种,并有2个相似种和8个未定种,这些属种为Glyptograptus perscuptus带常见分子。初步确定,该区柯坪塔格组时代为早志留世(兰多维列世)鲁丹阶—埃隆阶。根据笔石化石及岩石组合特征分析,柯坪塔格组中段沉积环境以陆棚相为主,水体能量较低,利于笔石化石保存;上段为近滨相沉积,水体能量较高,不利于笔石化石的保存。

The Kepingtage Formation in Sepabayi area of Xinjiang is mainly composed of schistosity shale and feldspathic quartz sand- stone with few fossils and very insufficient age data. At the bottom of the middle Kepingtage Formation well-preserved graptolite fos- sils were discovered, which included five graptolite genera with five species and two analogous species with eight indeterminate spe- cies. These fossils indicate an age of the Glyptohraptus perscuptus Biozone. Thus, the Kepingtage Formation in Sepabayi area is proba- bly latest Rhuudanian to Aeronian （Landovery） in age. According to the characteristics of graptolite combination and rock associa- tion, the sedimentary environment of the middle member of Kepingtage Formation should be continental shelf facies, and its water energy was low and beneficial to the preservation of graptolite fossils. The upper member was near shore facies unfavorable for the preservation ofgraptolite fossils due to its high water energy.