DEVELOPMENT OF VEGETATION AND CONTINENTAL ARIDITY IN NORTHWESTERN AFRICA DURING THE LATE PLIOCENE - THE POLLEN RECORD OF ODP SITE-658
DEVELOPMENT OF VEGETATION AND CONTINENTAL ARIDITY IN NORTHWESTERN AFRICA DURING THE LATE PLIOCENE - THE POLLEN RECORD OF ODP SITE-658
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DOI：
10.1016/0031-0182(94)90181-3
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发表时间：
1994-06-01
影响因子：
3
通讯作者：
DUPONT, L
中科院分区：
文献类型：
--
作者：
LEROY, S;DUPONT, L
ODP 658站点（北纬21度，西经19度）200 m长的海洋花粉记录揭示了非洲西北部3.7 ~ 1.7 Ma期间植被和大陆性气候的周期性波动。这些循环与氧同位素阶段平行。3.5 Ma以前，热带森林和红树林沼泽的分布达到了北纬5度的Cape Blanc。在3.5 ~ 2.6 Ma之间，森林在该纬度出现的时间间隔不规则，之后几乎消失。同样，撒哈拉古河流一直流动到同位素阶段134 （3.35 Ma）。当河流停止排水时，花粉粒的风输输优于河流输输。3.3 ~ 2.5 Ma信风花粉指标逐渐升高。在同位素阶段130 (3.26 Ma)，西北非洲的气候发生了强烈的干旱化。随后，湿润条件重新建立，随后是2.7 Ma左右的另一次干旱化。在2.6 ~ 2.4 Ma之间，植被带从树木繁茂的稀树草原向荒漠植物区反复的纬度转移首次占主导地位，这是对104、100和98冰期的响应。虽然上新世记录的气候条件不像更新世中期和晚期那样干燥，但上新世末期的纬度植被变化与布伦什时期的间冰期-冰期旋回相似。
A 200 m long marine pollen record from ODP Site 658 (21-degrees-N, 19-degrees-W) reveals cyclic fluctuations in vegetation and continental climate in northwestern Africa from 3.7 to 1.7 Ma. These cycles parallel oxygen isotope stages. Prior to 3.5 Ma, the distribution of tropical forests and mangrove swamps reached Cape Blanc, 5-degrees-N of the present distribution. Between 3.5 and 2.6 Ma, forests occurred at this latitude during irregular intervals and nearly disappeared afterwards. Likewise, a Saharan paleoriver flowed continuously until isotope Stage 134 (3.35 Ma). When river discharge ceased, wind transport of pollen grains prevailed over fluvial transport. Pollen indicators of trade winds gradually increased between 3.3 and 2.5 Ma. A strong aridification of the climate of northwestern Africa occurred during isotope Stage 130 (3.26 Ma). Afterwards, humid conditions reestablised followed by another aridification around 2.7 Ma. Repetitive latitudinal shifts of vegetation zones ranging from wooded savanna to desert flora dominated for the first time between between 2.6 and 2.4 Ma as a response to the glacial stages 104, 100 and 98. Although climatic conditions, recorded in the Pliocene, were not as dry as those of the middle and Late Pleistocene, latitudinal vegetation shifts near the end of the Pliocene resembled those of the interglacial-glacial cycles of the Brunhes chron.