| 华北克拉通东南部淮南地区晚前寒武纪寿县组碎屑岩粒度特征及锆石U-Pb年代学分析 |
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| 关键词:Shouxian Formation grain size analysis detrital zircon U-Pb dating maximum depositional age sediment provenance |
| 基金项目:国家自然科学基金项目(编号: 41902212); 矿山地质灾害防治安徽省重点实验室开放基金课题(编号: 2023-MGDP-06); 安徽省科技厅重点研发项目(编号: ZMXJ-LZ-JS-2020-16) |
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| Grain Size Characteristics and Zircon U-Pb Geochronological Analysis of Late Precambrian Clastic Rocks from the Shouxian Formation in the Huainan Region, Southeastern North China Craton |
| The Shouxian Formation is a set of Precambrian clastic strata widely distributed in the southeastern part of the North China Craton. However, its depositional age remains unclear. Due to the abundance of macroalgal fossils in the upper and lower adjacent strata of the Shouxian Formation, identifying its lithology, sedimentary environment, timing, and sources is of great importance. This will help in understanding Late Precambrian paleogeography, biostratigraphic sequence correlation, and sedimentary tectonic evolution. In this study, a detailed field investigation was conducted to determine the outcrop locations, lithologies, and sequence characteristics of the Shouxian Formation, based on Late Precambrian successions in the Huainan area. Microscopic observations, grain size analyses, and LA-ICP-MS detrital zircon U-Pb dating were performed on five rock samples to analyze the depositional environment, time constraints, and sediment source characteristics. The findings indicate that the Shouxian Formation consists of medium- to thick-bedded calcareous fine clastic rocks, occasionally interbedded with medium- to thin-bedded muddy layers. Grain size analysis showed that the formation belongs to the transitional type between fine sandstone and coarse siltstone. In terms of composition, it is dominated by suspended load components, with fewer saltation load components, indicating high maturity and weak depositional hydrodynamic conditions. The presence of glauconite minerals, along with the results from the Sahu discrimination function, suggests that sedimentation occurred in a shelf environment between the littoral and transitional zones. The youngest single-grain detrital zircon ages for the five samples are: (962±25) Ma, (963±31) Ma, (954±25) Ma, (952±24) Ma, and (976±26) Ma. The weighted average age of the youngest detrital zircon group, considering all samples, is (953±9) Ma. Combined with the intrusive age of the mafic sill complexes (943–876) Ma in the Xuzhou–Huaibei area, which intrude into the equivalent stratigraphic sequence, the depositional age of the Shouxian Formation is constrained between 953 and 943 Ma. The detrital zircon age spectrum of the Shouxian Formation shows a gradual increase in the number of detrital zircons since 1.8 Ga, with a significant abundance of zircons dated between 1.2 and 1.0 Ga. A comprehensive analysis suggests that the main sediment source for the Shouxian Formation likely originated from a landmass or landmass groups that were once connected outside the North China Craton. However, the interior of the North China Craton could also have served as a secondary source area. |
| GU Chengchuan,ZHAO Jiaqi,ZHAN Run,LI Aochen,DENG Shiji,YU Bo.2025.Grain Size Characteristics and Zircon U-Pb Geochronological Analysis of Late Precambrian Clastic Rocks from the Shouxian Formation in the Huainan Region, Southeastern North China Craton[J].Acta Geoscientica Sinica,46(4):777-799. |
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