DEVELOPMENT OF ASIAN MONSOON REVEALED BY MARKED ECOLOGICAL SHIFT DURING THE LATEST MIOCENE IN NORTHERN PAKISTAN
DEVELOPMENT OF ASIAN MONSOON REVEALED BY MARKED ECOLOGICAL SHIFT DURING THE LATEST MIOCENE IN NORTHERN PAKISTAN
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DOI：
10.1038/342163a0
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发表时间：
1989-11-09
期刊：
影响因子：
64.8
通讯作者：
BOWMAN, JR
中科院分区：
文献类型：
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作者：
QUADE, J;CERLING, TE;BOWMAN, JR
土壤碳酸盐1 - 4和土壤有机质5,6的碳同位素提供了古生态信息，因为土壤碳酸盐中的碳与当地土壤二氧化碳形成同位素平衡（参考文献1,7），其同位素组成又由当地植物覆盖决定。巴基斯坦北部的Siwalik群沉积物包含了一个暴露良好的古土壤记录，时间跨度超过18万年。在这里，我们报告了相关的成土碳酸盐的稳定碳同位素结果，表明从7.4-7.0 Myr以前开始，以漫滩为主的生物量发生了巨大的生态转变。c3河漫滩早期以乔木和灌木为主，而c4河漫滩在上新世—更新世以草地为主。在中新世晚期，氧同位素也出现了变化，这可能与导致森林向草原转变的重大气候变化相对应。中新世晚期的这种戏剧性的生态转变可能标志着亚洲季风系统的开始或显著加强。
CARBON isotopes from soil carbonate1–4and soil organic matter5,6yield palaeoecological information because the carbon in the soil carbonate forms in isotopic equilibrium with local soil CO2(refs 1, 7), the isotopic composition of which is in turn determined by local plant cover. Siwalik Group sediments in northern Pakistan contain a well exposed palaeosol record spanning the past 18 Myr. Here we report on stable-carbon-isotope results from associated pedogenic carbonate which indicate a dramatic ecological shift fromtodominated floodplain biomass beginning ∼7.4–7.0 Myr ago. The earlier C3floodplain biomasses were probably mainly composed of trees and shrubs, whereas C4grasslands dominated in the Plio-Pleistocene. Oxygen isotopes also exhibit a shift in the latest Miocene, probably corresponding to a major climate change which may have induced the forest-to-grassland transition. This dramatic ecological shift in the latest Miocene may mark the inception or a marked strengthening of the Asian monsoon system.