珠江三角洲万顷沙地区晚第四纪沉积相与古环境演变

EVOLUTION OF SEDIMENTARY FACIES AND PALEOENVIRONMENT DURING THE LATE QUATERNARY IN WANQINGSHA AREA OF THE PEARL RIVER DELTA

  • 摘要: 通过对广州万顷沙地区GZ-2孔年代地层学、沉积学、古环境学等多学科综合分析,认为该区全新世沉积起始时间为6 kaBP,始于孔深15.37 m处,其下至孔深40.35 m沉积属晚更新世中晚期沉积,最老年龄大约43 kaBP,与珠江三角洲最早沉积同期;晚更新世以来的沉积古环境变化可分为2个旋回,晚更新世中晚期海侵海退旋回(含4个次一级旋回)和全新世海侵海退旋回(含2个次一级旋回),在末次冰期时的低海平面期,本区仍发育有河湖相沉积;结合多种古环境重建替代性指标得出了珠江三角洲相对海平面变化曲线,认为晚更新世中晚期海侵高海平面期约为26~24 kaBP,全新世海侵高海平面期约为6~2.5 kaBP,全新世海侵比晚更新世中晚期海侵强度更大,且珠江三角洲晚第四纪古环境演变明显受全球性古环境变化控制。

     

    Abstract: Through the comprehensive analysis on chronostratigraphy, sedimentology, and paleoenvironment of core GZ-2 in Wanqingsha area of the Pearl River delta, it is suggested that the Holocene sedimentation began from the depth of -15.37 m (about 6 kaBP), and strata below this level to the depth of -40.35 m belong to middle-late late Pleistocene with a maximum dating value around 43 kaBP, contemporaneous with the earliest deposit in the Pearl River delta. In the profile, two cycles of transgression-regression can be recognized:the middle-late late Pleistocene(consisting of 4 sub-cycles) and the Holocene(consisting of 2 sub-cycles). It still has, in this area, fluvial-lake deposition facies during the lower sea level period of the Last Glaciation. The reconsruction of relative sea-level change curve of the Pearl River delta based on the multi-proxy index analysis indicates that the highest sea level period of the middle-late late Pleistocene was around 26~24 kaBP, and that of the Holocene was around 6~2.5 kaBP. The late Quaternary paleoenvironment evolution in the Pearl River delta was obviously controlled by global paleoenvironment changes.

     

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