| 凡欠荣,温汉辉,杨细乐,苏和明,刘曼,薛朋,彭文达,卢统庆.广东省清远市清城区晚更新世以来地层孢粉指示意义探究[J].矿产勘查,2023,14(12):2279-2287 |
| 广东省清远市清城区晚更新世以来地层孢粉指示意义探究 |
| Indicative significance of strata pollen since late Pleistocene in Qingcheng District， Qingyuan， Guangdong Province |
| 投稿时间：2023-07-31 修订日期：2023-12-12 |
| DOI：10.20008/j.kckc.202312001 |
| 中文关键词: 晚更新世 孢粉 古气候 古环境 清城区 广东省清远市 |
| 英文关键词: Late Pleistocene pollen paleoclimate paleoenvironment Qingcheng District Qingyuan, Guangdong Province |
| 基金项目:本文受清远市财政资金项目（441802-202001-405001-0001）资助。 |
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| 中文摘要: |
| 地层中保存的化石孢粉记录是重建历史时期古植被、古环境和古气候演变历史的重要指标。但是关于不同沉积环境中孢粉化石的保存状况，至今尚未开展针对性的研究。本文以广东省清远市清城区典型地质剖面中QK02钻孔为研究对象，试图通过孢粉组合分析揭示不同的沉积环境对孢粉化石记录保存的影响，在此基础上尝试性探讨清城区晚更新世以来的古植被和古环境演变历史。研究结果显示，清远市清城区晚更新世以来的孢粉保存情况总体较差：晚更新世地层统不含孢粉，主要可能原因为早期处于河流相沉积环境，不利于孢粉保存。此外，后期气候环境变化，降雨量降低，由河流沉积相转变为陆相剥蚀区，风化严重，也可能导致孢粉遭受破坏；早—中全新世孢粉组合中木本植物含量大量增加，特别是壳斗科的栲属和常绿栎属乔木大量增加，而落叶栎属和枫香属含量较低，反映常绿阔叶林占据优势的植被状况，表明该时期区域气候变化从冷干转向暖湿，同时该时期沉积环境主要为湖沼沉积相，有利于孢粉沉积保存；晚全新世气候变冷，导致森林逐渐减少，植被以由落叶栎属与栲属、常绿栎属与松属组成的森林植被为代表。然而，该阶段沉积物中孢粉含量极低，可能是洪水快速发育，使得沉积物主要来自山麓或其他剥蚀区风化壳的土壤，从而导致孢粉记录保存不完整。综合研究结果表明，在内陆河谷以河流相或风化剥蚀区为主的地区，第四纪沉积物具有横纵向变化快、物质组成复杂、同期异相等特征，可能不适合利用地层孢粉记录开展古环境重建工作。 |
| 英文摘要: |
| The fossil palynological record is an important index to reconstruct the evolution history of paleovegetation， paleoenvironment and paleoclimate. However， there has been no specific study on the preservation of pollen fossils in different sedimentary environments.In the case of QK02 core retrieved from a characteristic geologic strata in Qingcheng District of Qingyuan， Guangdong Province， this paper attempts to reveal the influence of different sedimentary environments on the preservation of palynological fossil records through pollen analysis. On this basis，this paper discusses the evolution of paleovegetation and paleoenvironment in Qingcheng District since Late Pleistocene. The results show that the pollen preservation in Qingcheng District is poor since the Late Pleistocene： There's no pollen in Upper Pleistocene， the main reason is likely that the early fluvial sedimentary environment isn’t conducive to pollen preservation. In addition， due to the change of climate and environment in the later period， the sedimentary environment changed from fluvial facies to terrestrial denudation， which may result in the destruction of pollen fossil. During Early to Middle Holocene， the concentration of xylophyta increased significantly，reflecting dominance of evergreen broad-leaved forests at that time.It shows that the cold and dry regional climate change to warm and wet condition during this period. The sedimentary facies of this period are mainly lacustrine facies， which is conducive to the deposition and preservation of pollen fossil. The cooling climate during the Late Holocene led to the gradual reduction of forests， and the vegetation was dominated by deciduous Quercus， Castanopsis， evergreen Quercus and Pinus. However， the pollen content in the sediments at this stage is very low， which may be due to the rapid development of flood， making the sediments mainly from the foothills or denudation areas， resulting in incomplete pollen records. According to comprehensive research， Quaternary sediments have the characteristics of rapid transverse and longitudinal changes， complex material composition and different phases at the same time in the inland river valley or weathered denudation area，it is not suitable to use the stratigraphic pollen subfossil records to reconstruct the paleoenvironment in the areas dominated by fluvial facies or weathering denudation area. |
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