Age model and color measurements of sediment cores from the eastern equatorial Pacific

High-resolution records of glacial-interglacial variations in biogenic carbonate, opal, and detritus (derived from non-destructive core log measurements of density, P-wave velocity and color; r >= 0.9) from 15 sediment sites in the eastern equatorial (sampling resolution is ~1 kyr) clear response to eccentricity and precession forcing. For the Peru Basin, we generate a high-resolution (21 kyr increment) orbitally-based chronology for the last 1.3 Ma. Spectral analysis indicates that the 100 kyr cycle became dominant at roughly 1.2 Ma, 200-300 kyr earlier than reported for other paleoclimatic records. The response to orbital forcing is weaker since the Mid-Brunhes Dissolution Event (at 400 ka). A west-east reconstruction of biogenic sedimentation in the Peru Basin (four cores; 91-85°W) distinguishes equatorial and coastal upwelling systems in the western and eastern sites, respectively. A north-south reconstruction perpendicular to the equatorial upwelling system (11 cores, 11°N-°3S) shows high carbonate contents (>= 50%) between 6°N and 4°S and highly variable opal contents between 2°N and 4°S. Carbonate cycles B-6, B-8, B-10, B-12, B-14, M-2, and M-6 are well developed with B-10 (430 ka) as the most prominent cycle. Carbonate highs during glacials and glacial-interglacial transitions extended up to 400 km north and south compared to interglacial or interglacial^glacial carbonate lows. Our reconstruction thus favors glacial-interglacial expansion and contraction of the equatorial upwelling system rather than shifting north or south. Elevated accumulation rates are documented near the equator from 6°N to 4°S and from 2°N to 4°S for carbonate and opal, respectively. Accumulation rates are higher during glacials and glacial-interglacial transitions in all cores, whereas increased dissolution is concentrated on Peru Basin sediments close to the carbonate compensation depth and occurred during interglacials or interglacial-glacial transitions.

本数据集包含东赤道海域15个沉积站位的生物碳酸盐（biogenic carbonate）、蛋白石（opal）及陆源碎屑（detritus）的冰期-间冰期高分辨率记录，数据源自密度、纵波速度（P-wave velocity）与颜色的无损岩心测井测量（non-destructive core log measurements），相关系数r≥0.9，采样分辨率约为1千年，该记录对轨道偏心率（eccentricity）与岁差（precession）驱动信号具有清晰响应。针对秘鲁海盆（Peru Basin），本研究构建了过去130万年的高分辨率（时间步长21千年）轨道年代标尺（orbitally-based chronology）。频谱分析（spectral analysis）结果显示，10万年周期在约120万年前成为主导周期，较其他古气候记录的报道结果早20至30万年。自中布容溶解事件（Mid-Brunhes Dissolution Event，发生于40万年前）以来，沉积物对轨道强迫的响应强度有所减弱。对秘鲁海盆生物沉积的东西向重建（覆盖4个岩心，采样范围91°W至85°W）分别区分了西部站位的赤道上升流系统与东部站位的沿岸上升流系统。垂直于赤道上升流系统的南北向重建（覆盖11个岩心，采样范围11°N至3°S）显示，6°N至4°S区间内碳酸盐含量较高（≥50%），2°N至4°S区间内蛋白石含量波动剧烈。碳酸盐旋回B-6、B-8、B-10、B-12、B-14、M-2及M-6均发育良好，其中以B-10（对应43万年前）为最显著的旋回。与间冰期或间冰期-冰期碳酸盐低值期相比，冰期及冰期-间冰期转换期的碳酸盐高值区向北、向南延伸可达400公里。因此，本重建结果更支持赤道上升流系统呈冰期-间冰期扩张与收缩模式，而非单纯的南北偏移。赤道附近6°N至4°S区间与2°N至4°S区间分别记录了碳酸盐与蛋白石的高堆积速率（accumulation rates）。所有岩心的堆积速率在冰期及冰期-间冰期转换期均更高，而增强的溶解作用集中在靠近碳酸盐补偿深度（carbonate compensation depth, CCD）的秘鲁海盆沉积物中，且发生于间冰期或间冰期-冰期转换期。