Volcaniclastic layers in ODP Site 202-1241

This study presents a record of dissolution from the eastern equatorial Pacific (EEP) that extends to 2.1 Ma, based on sediments from Ocean Drilling Program (ODP) Site 1241. A new benthic oxygen isotope record was developed in order to provide the stratigraphic framework for the Pleistocene section of the core. The isotope record extends back to 2.1 Ma, covering MIS 1-80, and has a sampling resolution of 2 kyr from 0 to 360 kyr and 5 kyr from 360 to 2100 kyr. Dissolution at ODP Site 1241 is characterized through the use of percent coarse fraction (%CF) and shell fragmentation records. These records indicate that %CF in the EEP is recording a dissolution signal dominated by the 41-kyr and 100-kyr climate cycles, and that preservation maxima lag glacial maxima by 9-14 kyr at the major orbital periods. The dissolution signals observed in the ODP Site 1241 record can be correlated across the Pacific and likely record the response to basinwide changes in carbonate chemistry. The dissolution fluctuations and d13C signal observed at ODP Site 1241 are consistent with both the [Shackleton, 1977] and [Toggweiler et al., 2006, doi:10.1029/2005PA001154] hypotheses that explain changes in the global carbon cycle during glacial-interglacial transitions.

本研究基于大洋钻探计划（Ocean Drilling Program, ODP）1241站位的沉积物，构建了可追溯至2.1 Ma的东赤道太平洋（eastern equatorial Pacific, EEP）溶解记录。为建立该岩心更新世（Pleistocene）段的地层框架，我们构建了全新的底栖氧同位素记录。该同位素记录可回溯至2.1 Ma，覆盖海洋同位素阶段（Marine Isotope Stage, MIS）1至80，采样分辨率为：0~360 kyr时段为2 kyr，360~2100 kyr时段为5 kyr。研究通过粗组分百分含量（percent coarse fraction, %CF）与壳体破碎记录，表征了ODP 1241站位的溶解作用特征。结果显示，东赤道太平洋的粗组分百分含量所记录的溶解信号以41 kyr和100 kyr气候周期为主，且在主要轨道周期尺度上，碳酸盐保存峰值较冰期峰值滞后9~14 kyr。本次在ODP 1241站位观测到的溶解信号可在太平洋全域进行对比，其大概率记录了对太平洋盆地碳酸盐化学变化的响应。该站位观测到的溶解波动与d13C信号，与[Shackleton, 1977]以及[Toggweiler et al., 2006, doi:10.1029/2005PA001154]提出的、用以解释冰期-间冰期转换期间全球碳循环变化的两项假说均保持一致。