气候变化和早期成岩作用对南海北部陆坡沉积物Ba循环的影响

Effects of Climate Change and Early Diagenesis on Barium Cycling in Sediments From the Northern Slope of the South China Sea

海底沉积物中的Ba具有多种来源。其中，生物成因Ba循环受气候变化和早期成岩作用的制约。南海北部陆坡ZHS-176站柱状沉积物无碳酸盐碎屑的Ba与陆源元素Ti的关系研究表明，南海北部陆坡沉积物中含有大量的生物成因Ba，在末次盛冰期，生物成因Ba占50％～60％。而自冰消期（15Cal．kaBP）以来，生物成因Ba的份额猛增至60％以上；在气候变冷事件发生期间（如Heinrichl，Younger Dryas和8ka冷事件），生物成因Ba骤然减少，体现了海平面变化和短时间尺度的气候对生物成因Ba对海底沉积物供应的制约；而在相对气候暖期Boiling-Allerod（B／A），发育明显的与浮游有孔虫碳同位素“负偏”相对应的生源Ba异常，很可能说明。

Barium in marine sediments derives from diverse sources, of which biogenic barium cycling is restricted by climate change and early diagenesis. The relationship between barium and titanium in the car- bonate-free sediments of core ZHS-176 drilled on the northern slope of the South China Sea indicates that the slope sediments contain a great fraction of biogenic barium, accounting for 50%-60% in the Last Gla- cial Maximum（LGM） and more than 60% since deglaciation （15Cal. ka BP）. During Heinriehl, Younger Dryas and the cooling event at 8ka BP, the biogenic barium decreased abruptly, indicating that the sea level changes and the short-term climatic cooling events controlled the supply of biogenic barium to the sediments. During the climate-warming period （Boiling/ Allerod）, however, a barium anormly corre- sponding exactly to the foraminifer negative carbon isotopic anormaly occurred obviously. This implies that the biogenic barium cycling in the slope sediments might be impacted by the early diagenesis related to the reaction between sulfate and methane.