西准噶尔乌兰柯顺地区晚泥盆世朱鲁木特组地层新知.docVIP

  西准噶尔乌兰柯顺地区晚泥盆世朱鲁木特 组地层新知# 王志宏，龚一鸣，纵瑞文，赵龙** 5 10 15 20 25 30 35 40 （中国地质大学生物地质与环境地质国家重点实验室,湖北武汉 430074） 摘要：将西准噶尔乌兰柯顺地区原划分为下石炭统和布克河组的一套地层重新厘定为朱鲁木 特组。该组与下伏志留纪火山岩地层为角度不整合接触关系，与上覆上泥盆统―下石炭统洪 古勒楞组为整合接触关系。根据在该组新发现的植物化石 Leptophloeum rhombicum 以及上 覆地层中发现的牙形石，将其时代确定为晚泥盆世早期。相标志表明，朱鲁木特组从底部到 顶部，其沉积环境由辫状河向曲流河演变，河流的下游方向为 NEE 方向。上述研究结果为 西准噶尔地区晚古生代地层的划分、对比、区域地质演化及沉积环境变迁提供了新资料和新 认识。 关键词：生物地层；地层划分；植物化石；朱鲁木特组；洪古勒楞组；晚泥盆世；西准噶尔； 新疆 中图分类号：P543.44 New knowledge on the Late Devonian Zhulumute Formation from Wulankeshun Region, Western Junggar WANG Zhihong, GONG Yiming, ZONG Ruiwen, ZHAO Long (State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074) Abstract: The lower Carboniferous strata were divided to the Hebukehe Formation in Wulankeshun region, which herein are redefined to the Zhulumute Formation. Our studies show that the Zhulumute Formation is angular unconformity with the underlying Silurian volcanic strata and conformity with the overlying Late Devonian-Early Carboniferous Hongguleleng Formation. The founded fossil plants (Leptophloeum rhombicum) and conodonts (Icriodus-Polygnathus assemblage) indicate that geological age of the Zhulumute Formation is the Late Devonian. Facies indicators show that from the bottom to top, sedimentary environments of the Zhulumute Formation are gradually from braided river to meandering river. The direction of downstream for the rivers is NEE. The new materials and understanding reported are significant for the stratigraphic subdivision and correlation, and the reconstruction of the Late Paleozoic palaeoenvironments and regional geological evolution in western Junggar. Key words: stratigraphy; stratigraphic division; plant fossils; Zhulumute Formation; Hongguleleng Formation; Late Devonian; Western Junggar; Xinjiang 0 引言 新疆西准噶尔地区泥盆纪到石炭纪火山活动强烈，地层岩性复杂，后期又经历了多次构 造运动的改造。长期以来，众多单位和学者对其进行了地层古生物学[1,2,3,4,5]、大地构造学[6,7,8] 岩石学地球化学和同位素年代学的研究[9,10]。尽管如此，由于该地区地质构造复杂、交通不 便、自然条件恶劣,仍存在一些问题，这给区域地层的划分对比、古环境恢复以及