Hydrogen isotope composition of pore waters and interlayer water in sediments of ODP Leg 129 holes@en

Hydrogen isotope compositions have been measured on pore waters from sediments of Leg 129 sites in the Pigafetta and East Mariana basins (central western Pacific). Total water (pore + sorbed waters) contents and their dD have been analyzed for three samples that contain smectite but no zeolite so that sorbed water can be attributed to interlayer water. The H budget for pore and total waters implies that interlayer water is 20 per mil to 30 per mil depleted in D compared to pore water. Because the interlayer/total water molar ratio (0.25 to 0.5) in smectitic sediments is very high, interlayer water represents an important reservoir of D-depleted water in sediments. […]本研究对西太平洋中部皮加费塔盆地（Pigafetta Basin）与东马里亚纳盆地（East Mariana Basin）129航次站位的沉积物孔隙水开展了氢同位素组成测定。针对3种仅含蒙脱石（smectite）、不含沸石（zeolite）的沉积物样品，本研究分析了其总水（孔隙水+吸附水）含量及氘同位素比值（dD），借此可将吸附水归因为层间水（interlayer water）。孔隙水与总水的氢元素收支分析表明，相较于孔隙水，层间水的氘亏损程度达20‰~30‰。由于蒙脱石质沉积物中层间水与总水的摩尔比介于0.25~0.5，数值较高，因此层间水是沉积物中重要的氘亏损水储库。[…]