Sea salt sulfate in the upper part of sediment column was dominantly reduced by AOM, and the remained sulfate involving reduction would probably cause positive sulfur isotopic excursion of pyrites.

• 海水源为主的硫酸盐参与了沉积物上部的AOM过程，黄铁矿硫稳定同位素正偏的原因可能与较强的AOM作用和较多的残余硫酸盐参与有关。