地质学报Issue(2)：185-197,13.
太原西山上古生界含煤地层最大沉积年龄的碎屑锆石U-Pb定年约束及地层意义
Constraints on U-Pb Dating of Detrital Zircon of the Maximum Depositional Age for Upper Paleozoic Coal-Bearing Strata in Xishan, Taiyuan and Its Stratigraphic Significance
摘要
Abstract
The standard stratotype section of Late Paleozoic coal-bearing strata of North China located in Xishan, Taiyuan.Since 1882,this section has been widely investigated on paleontology,stratigraphy,and sedimentology and fruitful achievement has been obtained. However, due to the lack of absolute chronology data,the chronostratigraphic boundaries have been changed several times,which affects the division and correlation of strata.To determine the timing for the formation of Late Paleozoic coal-bearing strata in Xishan,Taiyuan,a laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICPMS)was applied to date the U-Pb age of detrital zircon.Eight sandstone samples from the marker layers of strata division and correlation from Taiyuan,Shanxi and Xiashihezi Formations were analyzed and their maximum depositional ages were determined.Jinci sandstone in the lower part and and Qiligou sandstone in the upper of Taiyuan Formation showed YC1σ(2+)ages are 296±4 Ma and 277±2 Ma,respectively.62 zircons from Qiligou sandstone-A,constitute an age spectrum of 271-301 Ma,and the minimum age of the single zircons (YSG)is 271 ±7 Ma,representing the maximum depositional age. The U-Pb ages derived from both the Beichagou sandstone at the bottom of the Shanxi Formation and the Luotuobozi sandstone at the bottom of the Lower Shihezi Formation are greater than that of the Qiligou sandstone,so they cannot be used to constrain the maximum depositional age of the Shanxi Formation. Comparison with the conodont biostratum of the Taiyuan Formation indicates that the Taiyuan Formation was undoubtedly formed during the Early Permian.However,the U-Pb dating results of the detrital zircon reveal that the Taiyuan Formation deposited for four stages, including the Asselian, Sakmarian, Artinskian,and Kungurian. What ’s more, the Taiyuan formation even deposited into the Middle Permian,rather than only the Asselian deposition that was determined by conodonts.As a result, Carboniferous-Permian boundary may be located next or below the bottom boundary of Jinci sandstone. According to the sedimentology,petrology and eventstratigraphy results of Xishan,Taiyuan and the whole North China,we cannot rule out the possibility that magmatism and volcanism occurred during Late Carboniferous and Early Permian.关键词
砂岩碎屑锆石/U-Pb定年/上古生界含煤地层/牙形石/太原西山剖面Key words
sandstone detrital zircon/U-Pb dating/late Paleozoic coal-bearing strata/conodont/section of Xishan,Taiyuan引用本文复制引用
孙蓓蕾,曾凡桂,刘超,崔秀琦,王威..太原西山上古生界含煤地层最大沉积年龄的碎屑锆石U-Pb定年约束及地层意义[J].地质学报,2014,(2):185-197,13.基金项目
本文为中国国家自然科学基金（Nos．41072116，40772097，41102092，41103052）、高等学校博士学科点专项科研基金（No．20091402110002）、2010年山西省研究生优秀创新项目及2012太原市科技项目（No．120247-27）的资助成果。 （）
