高级检索

    珠江三角洲晚第四纪沉积的OSL和14C年龄探讨

    OSL and 14C ages of the Late Quaternary sediments in the east Pearl River Delta

    • 摘要: 提要:珠江三角洲第四纪沉积的年代测定在三角洲的发育演化、古海平面变化以及断裂活动性研究等方面具有重要意义。对东江平原的7个钻孔岩心进行了14C和OSL测年以及孢粉和微体古生物分析。与前人主要根据14C年龄得到珠江三角洲沉积小于4万年的认识不同,OSL测年结果显示下部地层的年龄值为4.7~13.5万年。本文对年龄的信度以及晚第四纪两次海侵旋回的地层年代框架进行了初步分析,提出珠江三角洲地区第一次海侵旋回可能发生于距今4~10万年期间;在晚更新世与全新世两次海侵之间,三角洲地区长期暴露地表,出现较大跨度的地层缺失。

       

      Abstract: Abstract: The dating of the Late Quaternary sediments in the east Pearl River Delta has great significance in many aspects, such as the study of the delta's evolution, the fluctuation of the ancient sea level and fault activities. The OSL and 14C dating was performed for the core from seven drill holes in Dongjiang plain, and sporopollen and micropaleontology analysis was conducted. Different from the former conclusion based mainly on 14C age that the oldest deposit of the delta is less than 40 000 a, the authors' OSL dating demonstrates that the age of the lower strata is about 47 000 to 135 000 a. Based on a preliminary analysis of the age reliability and stratigraphic geochronological framework of the two transgression cycles during the Late Quaternary, the authors hold that the first transgression of the east Pearl River Delta might have occurred 40 000 to 80 000 a ago, and the erosion and weathering effect led to the considerable stratigraphic gap between the two transgressions.

       

    /

    返回文章
    返回