Study on the porosity of a metalliferous sediment core from the East Pacific Rise 13°N
东太平洋海隆(EPR) 13°N 附近含金属沉积物孔隙率研究

The porosity of a metalliferous sediment core E272 collected from 13°N East Pacific Rise(EPR 13°N) was studied.The porosity of this core monotonically decreases with increasing depth rangeing from 70.0%-85.2% with difference of about 14% between its top layer and its bottom and an average decreasing gradient of about -0.31%/cm.The red-brown color of the upper layers and yellow-green color of the lower layers of this core indicate early chemical diagenesis has exerted significant influence on this core.A combined analysis of reported geo-chemical,grain-size and chronological data of this core suggests that the porosity of this core might be controlled by steady-state-compaction process.The profile of its porosity versus depth fits well with the steady state compac-tion model.Exchanging mechanism of dissolved materials between bottom sea water and the sediment at the wa-ter-sediment interface is dominated by molecular diffusion,while under that interface,the mechanism controlling the transportation of dissolved materials is the directed flow of the interstitial water from the bottom up,and this is consistent with the profiles of labile elements versus depth of this sediment core.This study is instructive for further study on the chemical diagenesis of this sediment core.