【摘要】 通过对渤海湾西北岸大吴庄牡蛎礁壳体内部的泥质填充物中硅藻组合的研究,试图探讨该区沉积硅藻组合变化指示的礁体古气候环境变化。分析结果表明,在7200～5600cal.a BP整个礁体建造期间,沿岸种Cyclotella stylorum是含量最丰富的硅藻种类,其与海水种Thalassionema nitzschioides的含量变化指示了礁体生长区河流径流与海水相互作用的强弱波动,主要包括三个阶段:7200～6500cal.a BP,礁体建造初期,礁体受海水影响显著;6500～5720cal.a BP,礁体建造中期,礁体生长区的盐度降低,海水作用减弱,淡水作用增强;5720～5600cal.a BP,礁体建造结束期,礁体生长区的盐度显著降低,礁体受海水影响进一步减弱。更多还原

【Abstract】 With the analysis of the diatom assemblage in the muddy deposition, which were filled in the two valves of oyster shells in the buried oyster reef at Dawuzhuang, the reconstruction of the paleo-environmental change recorded by the whole reef during 7 200 to 5 600 cal. a BP is studied. The littoral species Cyclotella stylorum is the dominated diatom during the whole reef buildup, and the amount of Cyclotella stylorum fluctuant B opposite with the neritic species Thalassionema nitzschioides. The increase or decrease of the amount of Cyclotella stylorum and Thalassionema nitzschioides is the indicator of salinity fluctuation in the reef living environment. The whole period of the reef buildup can be divided into three phases, during 7 200 - 6 500 cal. a BP, and at the beginning of the reef buildup, the reef environment had high salinity; during the 6 500-5 720 cal. a BP, the amount of literal species increased and more fresh water input to the oyster living area; during 5 720 - 5 600 cal. a BP, while near the end of the reef buildup, the neritic species almost disappeared and the reef was dominated by the input of freshwater.更多还原