Calcareous dinoflagellate cysts and geochemistry of Mediterranean Sea sediments

Comparison of calcareous dinoflagellate cyst assemblages with Ba, Al, Mn, and Fe records from three sediment cores collected in the eastern Mediterranean Sea indicate that calcareous dinoflagellate cysts are generally resistant to postdepositional dissolution. Cyst association changes during and after sapropel S1 formation can therefore be closely related to variability in surface water productivity. Two groups of cysts are defined: those having highest abundances within the sapropelic and postsapropelic sediments. The temporal cyst distributions suggest increased freshwater input mainly from the Nile and a shallowing of the pycnocline as the most important processes increasing nutrient concentration in the photic zone, thus leading to increased productivity and organic carbon fluxes during sapropel formation. Furthermore, a general warming trend at the beginning of S1 formation and a slight salinity decrease are reconstructed.

对东地中海海域3根沉积岩芯中的钙质甲藻孢囊（calcareous dinoflagellate cyst）组合与钡（Ba）、铝（Al）、锰（Mn）、铁（Fe）记录开展对比分析，结果显示钙质甲藻孢囊整体具备较强的抗沉积后溶解能力。因此，腐泥层S1形成期及形成后的孢囊组合变化，可与表层水生产力的波动紧密关联。本研究划分出两类孢囊：一类在腐泥层及腐泥层后沉积物中丰度最高。孢囊的时间分布特征表明，主要源自尼罗河的淡水输入增加与密度跃层变浅，是提升透光带营养盐浓度的两大关键过程，进而在腐泥层形成阶段推动了生产力与有机碳通量的提升。此外，研究还重建出S1形成初期存在整体升温趋势，且盐度小幅下降的古环境演化结果。