禹州地区山西组和上石盒子组地层沉积时限及地质意义
- 收稿日期:
2023-09-19
- 网络出版日期:
2024-04-07
摘要: 禹州地区是华北板块南部上古生界含煤地层研究程度最高的地区,具有丰富的沉积学和地层古生物学研究基础,但由于缺乏绝对年代学数据而影响了年代地层划分及区域上大尺度的地层对比。本文选取禹州地区太原组与山西组、下石盒子组与上石盒子组地层界线附近的两件泥岩样品,通过碎屑锆石LA-ICP-MS U-Pb定年测试技术,进而确定它们的地层最大沉积年龄结果表明:①山西组底部样品(ZK1006-5)的40颗碎屑锆石构成了283Ma~343Ma的连续年轻组分频谱,其最年轻单颗粒锆石年龄(YSG年龄)为283±9.4Ma;上石盒子组底部样品(ZK2387-3)的18颗碎屑锆石构成了257Ma~299Ma的连续年轻组分频谱,其最年轻单颗粒锆石年龄(YSG年龄)为257±6.8Ma;其分别可代表样品地层最大沉积年龄,表明沉积时间不早于283±9.4Ma和257±6.8Ma;②禹州地区山西组、上石盒子组沉积分别开始于空谷期(Kungurian)和吴家坪期(Wuchiapingian),与区域生物地层资料研究相一致;③华北板块上古生界含煤地层岩石地层穿时明显,且跨度较大,整体表现为由板块边缘向内部逐渐穿时变新特点。综合前人对华北晚古生代盆地火山事件沉积相关研究,认为其同沉积期盆地东缘活动强烈,其诱发的岩浆活动、构造活动、生物演替和海侵作用可能与同时期逐渐形成劳亚古大陆有关。
The Stratigraphic Depositional Age of Shanxi Formation and Shang Shihezi Formation in Yuzhou Area and its Geological Significance
- Received Date:
2023-09-19
- Available Online:
2024-04-07
Abstract: The Yuzhou area is the most highly studied on Upper Paleozoic coal-bearing strata of the southern part of North China Block, which has abundant sedimentological and stratigraphic paleontological research basis, however, due to the lack of absolute chronology data, the division of chronostratigraphy and regional large-scale stratigraphic correlation are affected. In this paper, a laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was applied to date the U-Pb age of detrital zircon of two mudstone samples near the stratigraphic boundary of Taiyuan-Shanxi Formations and Xiashihezi-Shangshihezi Formations in Yuzhou area, and to determine their maximum depositional ages. The results show that: ①The 40 detrital zircons from the bottom sample of Shanxi Formation (ZK1006-5) constitute a continuous young component spectrum ranging from 283Ma to 343Ma, with the youngest single zircon age (YSG age) is 283±9.4Ma. The 18 detrital zircons from the bottom sample of Shangshihezi Formation (ZK2387-3) constitute a continuous young component spectrum ranging from 257Ma to 299Ma, with the youngest single zircon age (YSG age) is 257±6.8Ma.They can represent the maximum deposition age of the sample strata, indicating that the deposition time is no earlier than 283±9.4Ma and 257±6.8Ma. ②The deposition of Shanxi Formation and Shangshihezi Formation in Yuzhou area began in Kungurian and Wuchiapingian, respectively, which is consistent with regionnal biostratigraphic data. ③The Upper Paleozoic coal-bearing strata of the North China Block have obvious and large span of rock strata penetrating, and the overall performance is characterized by inward penetrating of the plate edge gradually through the new characteristics. Based on the previous studies on volcanic events in the Late Paleozoic basin of North China Block, it is concluded that the eastern margin of the basin was strongly active in which the same sedimentary period, and the induced magmatism, tectonic activity, biological succession and transgression may be related to the formation of the ancient continent of Laurisia land at the same time.