摘要:
海岸带海侵研究具有重要的理论和现实指导意义。第四纪以来,渤海湾沿岸地区受海平面升降波动影响发生多次海进和海退事件。对渤海湾地区已发表的钻孔资料进行整理和分析,结果显示该区早-中更新世海侵在空间上分布较为局限且变化较大,对于早更新世海侵存在与否仍存有争议,而大规模海侵发生在晚更新世以来MIS5、MIS3和MIS1时期。研究表明本区海侵的发生是在第四纪以来持续构造沉降的背景下,间冰期气候变暖造成海平面上升的结果。MIS3时期强烈的区域性"视海侵"在空间上并非普遍存在:在靠近渤海湾的地区,MIS3时期海侵为水深较深的滨海-浅海相沉积;而向内陆方向,该时期沉积转变为海陆过渡相和陆相。对于这种现象,一种解释是该区当时西高东低的地势起伏较大,海水逐渐向内陆侵入形成同期异相;另一种可能原因是由于冰盛期时河流侵蚀作用加强,靠近内陆地区的MIS3时期海侵沉积遭受后期河流侵蚀,其确切原因或者是否还存在其他因素,如以前测得的MIS3海侵实际在MIS5形成还需进一步研究。
Abstract:
Marine transgressions and regressions occurred frequently along the Bohai Bay during the Quaternary period due to sea level changes. The stratigraphic and chronologic data from previously published cores suggest that the early-middle Pleistocene marine transgressions are limited in small areas, and uncertainties still remain with its existence. Large-scale transgressions occurred mainly in MIS5, MIS3 and MIS1 of Late Pleistocene. It is believed that the transgression was caused by sea-level rises induced by interglacial climate under a long-term tectonic background of subsidence. During the period of MIS3, due to the effect of topography, which was higher in west and lower in east, shallow marine deposits were formed in the basin with transitional and continental deposits formed along the coast with gradual sea level rise. Some researchers argued that that transgression deposits formed MIS3 in the inland area may have been eroded during the following glacial. Further researches are required to reveal the cause.
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