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| 上新世末～更新世初西太平洋变冷事件及其古气候意义 | |
| 引用本文： | 王律江.上新世末～更新世初西太平洋变冷事件及其古气候意义[J].第四纪研究,1996,16(4):300-309. |
| 作者姓名： | 王律江 |
| 作者单位： | 1. 同济大学海洋地质系,上海 200092; 2. 基尔大学地质古生物研究所,德国 |
| 基金项目： | 国家教委基金,国家自然科学基金,亚历山大·冯·洪堡基金 |
| 摘 要： | 依据深海沉积中浮游有孔虫化石群落，采用时间面与时间系列分析及目标转换函数方法，再造西太平洋近2.6Ma以来表层水温历史。结果表明，上新世末～更新世初，西太平洋曾经历一大幅度、不可逆性质的温降。变冷事件集中发生于2.4～1.0MaB.P.间，主要体现在亚热带水团，冬、夏降温幅度达7～8℃和2-3℃，热带水团相对稳定。西太平洋温度场巨变表明其在北半球冰川发展过程中的正、负反馈作用，并由此奠定了中、晚更新世冰期旋回的全球气候模式。 |
| 关 键 词： | 西太平洋 古温度 上新世末～更新世初 古气候及古海洋学 |
| 收稿时间： | 1996-02-06 |
| 修稿时间： | 1996-08-16 |
MAJOR TEMPERATURE DECREASE IN THE WESTERN PACIFIC DURING LATE PLIOCENE TO EARLY PLEISTOCENE AND ITS PALEOCLIMATIC IMPLICATIONS |
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| Institution: | 1. Department of Marine Geology, Tongji University, Shanghai 200092; 2. Geologic-Paleontologic Institute Kiel University, Germany |
| Abstract: | Based on the planktonic foraminifera(PF) faunal data from eight DSDP cores in the Western Pacific (0 ～32°N, 124～159°E), paleotemperature has been reconstructed for the last 2.6 Ma using a stratgey of combined time-series and time-slice analyses. The last 2.6 Ma has been divided into two time intervals (0～2.OMa and 1.8-2.6Ma) by a time-slice (1.8-2.OMa) in between. On mis time slice, the concurrence of the last and first appearance of extinct and new species enables the development of a PF paleotemperature transfer function (TTF-1) for the time interval of 1.8～2.6 Ma.The target transfer function TTF-1 is based on the fossil PF fauna analogous tO those in the 1.8-2.6Ma and calibrated to the paleotemperatures of the time-slice estimated using transfer function FP-12E. Statistic quality control of TTF-1 shows high correlation (R:0.95～0．99) between the estimated values of the two transfer functions, TTF-1 and FP-12E, on the time slice. The standard errors of estimation of TTF-1 are 1.6℃ and0.6℃ for winter and summer temperatures, especially in the range of 17.5 ～ 27.5℃ and 26.5 ～29.5℃, respectively..The estimated paleotemperature curves show a major cooling during late Pliocene to early Pleistocene in the western Pacific, espedcially in the subtropical latitudes, with temperature decrease reaching 7～8℃ and 2～ 3℃ for winter and summer respectively. This cooling is stepwise and irreversible in nature, resulting in the establishment of the western Pacific temperature field of the late Pleistocene characteristic of a strong seasonality. An abrupt cooling is observed in cooler subtropical site 577 at 2.4～2.2 MaB.P., while the cooling starts from 2.2～2.0 MaB.P. at warmer subtropical sites 296 and 445 with temperatures at there sites decreasing gradually until the minima are reached at about 1.0 MaB.P. The equatorial-tropical sins generally show small changes in temperature, with a stepwise decrease seen only at sites 292 and 62.1 in the western boundary current region.The major cooing event across the Plio-Pleistocene boundary coincides with the major global climatic changes-the development of the northern hemisphere glaciation and the major change in climate in Asian continent. This indicates the influence of the change in position and strength of the most important ocean heat sougrce associated with the warm water pool in the western Pacific. During the late Pliocene, the warm who Pacific surface water provides the mecessary moistUre to the high latitudes to build up the ice sheets in the northern hemisphere. After the cooling at 2.4 ～2.2 MaB.P., the meridional temperature gradient increases in the subtropical region indicating the strengthening of the subpolar gyre, and the warm water mass reduced its magnitude with a displacement to- Wards the eqUator' the moistUre SUPply balance the gladal deVelopment, and during thefollowing 2.2 ～1.0 MaB.P. the temperature gradually reaches its minimum and this dynamic result in the final establishment of the glacial-interglacial environment characteristic of the late Pleistocene. The gradual reduction in landward transport of sensi- ble and latent heat during this the result in the development of cold-dry environment in inner Asia. This is the period when the oldest Loess-paleosol formation (Wucheng Loess)deposits over the Pliocene Red Clay in northern China. Increased seasonality during this time may also indicate the possible relationship between the change in westrn Pacific temperature field and the development of East Asian monsoon climate. |
| Keywords: | western Pacific paleotemperature late Pliocene～ early Pleistocene paleoclimatology～ paleoceanography |
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