(Table 2) Composition nd atomic ratios of the proto-kerogen concentrates in ODP Hole 165-1002C samples

Sorg was obtained by subtracting pyritic S (calculated from Fe content assuming that Fe exclusively occurs as pyrite) from total S (measured by elemental analysis). Accordingly, these values, and hence the Sorg/C ratios, are not obtained with high precision and rounded numbers are reported. However, (i) these Sorg/C values point to a low level of sulfurisation for the proto-kerogen of the shallowest sample (in agreement with S measurements from Were et al., 2003, doi:10.1016/S0009-2541(02)00393-5) and to an increasing trend with depth and (ii) these two features are supported by light microscopy and pyrolysis observations.本数据集所涉Sorg由总硫（total S，经元素分析测定）减去黄铁矿硫（pyritic S）计算得到；其中黄铁矿硫依据铁含量推算，假设铁仅以黄铁矿相赋存。据此，本次测得的Sorg数值及由此得到的Sorg/C比值精度有限，故报告值均为修约后结果。 不过，（i）上述Sorg/C比值显示，最浅部样品的原始干酪根（proto-kerogen）硫化程度偏低（与Were等人2003年的硫含量测定结果[doi:10.1016/S0009-2541(02)00393-5]一致），且硫化程度随深度呈升高趋势；（ii）上述两项特征均得到光学显微镜观测与热解分析结果的支持。