渤海湾西南部平原DC01孔晚更新世以来的地质环境变化

李建芬; 王福; 陈永胜; 方晶; 商志文; 田立柱; 施佩歆; 姜兴钰; 王宏

渤海湾西南部平原DC01孔晚更新世以来的地质环境变化

Geo-environmental changes since the Late Pleistocene recorded by Borehole DC01, the southwest plain of Bohai Bay

摘要

摘要: 通过对渤海湾西南部平原DC01孔的岩石地层学、生物地层学及年代地层学和地球化学研究，重建了该地区自晚更新世以来的地质环境演化过程。全新世之前，研究区经历了由河流-盐沼-潮间带上部/低盐沼-河口湾-泻湖-淡化泻湖的环境转化过程；进入全新世之后，该区经历了由湖沼到河流的环境转化过程。埋深22.4~12.7m发育近10m厚的弱海相沉积，AMS ¹⁴C年龄表明，该层沉积形成时间早于4.35ka cal BP，可能属于MIS 3早期（6.0~5.5ka cal BP）或更早的MIS 5期（12~8ka cal BP）。恢复了该时期的相对古海面，最高可达-13.31m。DC01孔缺失MIS 4~2或MIS 2时期的沉积。

Abstract: Geo-environmental history since the Late Pleistocene was reconstructed by the study of litho-, bio- and chronostratigraphy and geochemistry of Borehole DC01 drilled in the southwest plain of Bohai Bay. Before the Holocene, the study area had experienced environmental transformation of river- salt marsh- upper intertidal/lower salt marsh-estuary-lagoon-desalinated lagoon environments. During the Holocene, the area changed from lacustrine to fluvial environment. The less marine- influenced sediments, nearly 10m thick, were found at the depth of 22.4~12.7m. AMS ¹⁴C ages show that such sediments were formed earlier than 4.35ka cal BP, thus probably during the earlier stage of MIS 3 (6.0~5.5ka cal BP) or even MIS 5 (12~8ka cal BP). Relative sea level for this period was also reconstructed with a highest elevation at -13.31m. Borehole DC01 lacks the sediments deposited in the period of MIS 4~2 or MIS 2.

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