Late Pleistocene Continental Climate and Oceanic Variability Recorded in Northwest Pacific Sediments
Late Pleistocene Continental Climate and Oceanic Variability Recorded in Northwest Pacific Sediments
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DOI：
10.1029/91pa00559
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发表时间：
1991-06
期刊：
影响因子：
--
通讯作者：
S. Hovan;D. Rea;N. Pisias
中科院分区：
文献类型：
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作者：
S. Hovan;D. Rea;N. Pisias
核心 V21-146 提供了过去 53 万年西北太平洋远洋沉积的连续记录。底栖有孔虫方解石的 δ18O 岩心变化与 SPECMAP 记录相关，为更新世晚期古气候和古海洋变化提供年龄模型。 CaCO3 和风积物质的通量是通过结合线性沉降速率、堆积密度和成分百分比的信息来确定的。 CaCO3 的质量累积率 (MAR) 从 58 到 1435 mg(cm² kyr)−1 不等，并且在记录的较新部分表现出与冰河期相关的太平洋较高累积模式。然而，CaCO3 积累的模式似乎在布伦赫斯中期发生了变化，因此在 35 万年前，它在间冰期表现出相反的更大积累模式。风尘通量是源区干旱度的替代指标，与中国的黄土-土壤地层有很好的相关性。灰尘通量范围为 43 至 718 mg(cm² kyr)−1，在冰河时期大约增加 4 倍。风成通量和氧同位素记录的交叉光谱分析显示，在 100、41 和 19 kyr 的每个主要轨道周期处存在同相和相干关系。风成颗粒尺寸通常用作风强度的代理记录，范围从 8.4ф (2.9 µm) 到 6.2ф (13.6 µm)。晶粒尺寸变异性的变化发生在大约 300 ka 附近，使得较旧的部分比较新的部分具有更低频率和更高振幅的波动。风成颗粒尺寸记录的功率谱显示 100 和 50 kyr 处的主峰以及 25-35 kyr 的宽峰，但仅在 100 和 33 kyr 周期处与氧同位素曲线具有一致性。风成颗粒尺寸和 δ18O 记录之间偏心率的相位关系表明，在 100 kyr 频率下，最小颗粒尺寸与冰川条件相关。
Core V21-146 provides a continuous record of northwest Pacific pelagic sedimentation spanning the past 530,000 years. Downcore variations of δ18O from benthic foraminiferal calcite were correlated to the SPECMAP record to provide an age model for late Pleistocene paleoclimatic and paleoceanographic variation. Fluxes of CaCO3 and eolian material have been determined by combining information about linear sedimentation rates, bulk densities and component percentages. The mass accumulation rate (MAR) of CaCO3 varies from 58 to 1435 mg(cm² kyr)−1 and exhibits the Pacific Ocean pattern of higher accumulation associated with glacial periods for the younger portion of the record. However, the pattern of CaCO3 accumulation appears to shift during the mid-Brunhes so that prior to 350,000 years ago it exhibits an opposite pattern of greater accumulation during interglacial periods. The flux of eolian dust is a proxy measure of the source area aridity and correlates well to the loess-soil stratigraphy in China. Dust fluxes range from 43 to 718 mg(cm² kyr)−1 and are greater by a factor of about 4 during glacial times. Cross-spectral analysis of the eolian flux and oxygen isotope records shows an inphase and coherent relationship at each of the major orbital periodicities of 100, 41, and 19 kyr. Eolian grain sizes, generally used as a proxy record of wind intensity, range from 8.4ф (2.9 µm) to 6.2ф (13.6 µm). A change in grain size variability occurs near about 300 ka such that the older portion is characterized by lower-frequency and higher-amplitude fluctuations than the younger portion. Power spectra for the eolian grain size record show dominant peaks at 100 and 50 kyr and a broad 25–35 kyr peak but coherency to the oxygen isotope curve at only the 100 and 33 kyr periodicities. The phase relationship for eccentricity between the eolian grain size and δ18O records suggests that at the 100 kyr frequency the smallest grain sizes are associated with glacial conditions.