Depth profiles of sediment thermal conductivity are required for understanding the thermal structure in active seismogenic zones. During the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE), a scientific drilling project of the International Ocean Discovery Program (IODP), a borehole was penetrated to a depth of 3,262.5 m below seafloor (mbsf) at Site C0002. Because core samples obtained from below ~1,100 mbsf in an accretionary prism are limited, a thermal conductivity profile over such depths usually determined by laboratory measurements using core samples is not available. To obtain the thermal conductivity profile at Site C0002, we used core samples collected from sediments that overlay the incoming subducting oceanic basement at Nankai Trough Seismogenic Zone Experiment Site C0012, which can be considered to have the same mineral composition as the accretional prism at Site C0002. The thermal conductivity of the C0012 core samples was measured at high pressure to simulate subduction by reducing the sample porosity. We measured the thermal conductivity of six core samples from 144–518 mbsf at Site C0012 up to a maximum effective pressure of ~50 MPa, corresponding to depths greater than ~4 km below seafloor. We obtained an empirical relation between thermal conductivity λ _Bulk in Wm^‐1K^‐1 and fractional porosity ϕ for the Nankai Trough accretionary prism as λ _Bulk = exp(−1.09ϕ  + 0.977). Based on porosity data measured using core/cuttings samples and data derived from P wave velocity logs, we estimate two consistent and complete thermal conductivity profiles down to ~3 km below seafloor in the Nankai Trough accretionary prism. These profiles are consistent with the existing thermal conductivity data measured using limited core samples.

中文翻译：

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IODP NanTroSEIZE站点C0002的Nankai增生棱镜中的热导率曲线：使用输入站点沉积物进行的高压实验估算

沉积物热导率的深度剖面是了解活跃地震发生区热力结构所必需的。在国际海洋发现计划（IODP）的科学钻探项目“南海海槽地震成因区实验（NanTroSEIZE）”中，C0002站点的海底（mbsf）下方钻入了3,262.5 m的深度。由于在增生棱镜中从约1100 mbsf以下获得的岩心样品受到限制，因此通常无法通过使用岩心样品通过实验室测量确定的这种深度上的导热系数分布。为了获得站点C0002处的热导率分布图，我们使用了从沉积物收集的岩心样本，这些沉积物覆盖了南开槽地震发生区实验站点C0012上传入的俯冲海洋基底，可以认为其矿物成分与站点C0002的增生棱镜相同。在高压下测量C0012岩心样品的热导率，以通过降低样品的孔隙率来模拟俯冲。我们在站点C0012处测量了从144–518 mbsf到最高有效压力约50 MPa的六个岩心样品的热导率，对应于大于海底以下约4 km的深度。我们获得了热导率之间的经验关系 对应于海底以下大于4 km的深度。我们获得了热导率之间的经验关系 对应于海底以下大于4 km的深度。我们获得了热导率之间的经验关系Wm ^-1 K ^-1中的λ_体积和Nankai槽增生棱镜的孔隙率ϕ为λ_体积 = exp（−1.09 ϕ  + 0.977）。根据使用岩心/岩屑样品测得的孔隙度数据以及从P波速度测井获得的数据，我们估算了南开海槽增生棱镜中海底以下约3 km处的两个一致而完整的导热系数曲线。这些曲线与使用有限岩心样品测得的现有热导率数据一致。