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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Lateral variations in vegetation in the Himalaya since the Miocene and implications for climate evolution
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Lateral variations in vegetation in the Himalaya since the Miocene and implications for climate evolution

机译：自中新世以来喜马拉雅植被植被的横向变化及气候进化的影响

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摘要

The Himalaya has a major influence on global and regional climate, in particular on the Asian monsoon system. The foreland basin of the Himalaya contains a record of tectonics and paleoclimate since the Miocene. Previous work on the evolution of vegetation and climate has focused on the central and western Himalaya, where a shift from C3 to C4 vegetation has been observed at similar to 7 Ma and linked to increased seasonality, but the climatic evolution of the eastern part of the orogen is less well understood. In order to track vegetation as a marker of monsoon intensity and seasonality, we analyzed delta C-13 and 8180 values of soil carbonate and associated delta C-13 values of bulk organic carbon from previously dated sedimentary sections exposing the syn-orogenic detrital Dharamsala and Siwalik Groups in the west, and, for the first time, the Siwalik Group in the east of the Himalayan foreland basin. Sedimentary records span from 20 to 1 Myr in the west (Joginder Nagar, Jawalamukhi, and Haripur Kolar sections) and from 13 to 1 Myr in the east (Kameng section), respectively. The presence of soil carbonate in the west and its absence in the east is a first indication of long-term lateral climatic variation, as soil carbonate requires seasonally arid conditions to develop. delta C-13 values in soil carbonate show a shift from around -10 parts per thousand to -2 parts per thousand at similar to 7 Ma in the west, which is confirmed by delta C-13 analyses on bulk organic carbon that show a shift from around -23 parts per thousand to -19 parts per thousand at the same time. Such a shift in isotopic values is likely to be associated with a change from C3 to C4 vegetation. In contrast, delta C-13 values of bulk organic carbon remain at 23 parts per thousand o in the east. Thus, our data show that the current east -west variation in climate was established at similar to 7 Ma. We propose that the regional change towards a more seasonal climate in the west is linked to a decrease of the influence of the Westerlies, delivering less winter precipitation to the western Himalaya, while the east remained annually humid due to its proximity to the monsoonal moisture source. (C) 2017 Elsevier B.V. All rights reserved.
机译：喜马拉雅亚对全球和地区气候有重大影响，特别是亚洲季风系统。喜马拉雅的前陆盆地包含自新世以来的构造和古光芒的记录。以前的植被和气候进化的工作主要集中在喜马拉雅中西部和西方​​喜马拉雅州，其中已经观察到从C3到C4植被的转变，类似于7 mA，并与季节性增加相关，但东部的气候演变有关。 orogen很不明朗地理解。为了跟踪植被作为季风强度和季节性的标志物，我们分析了增量C-13与土壤碳酸盐的8180个值和相关增量C-13散装有机碳的值从先前日期的沉积剖面露出同造山碎屑达兰萨拉和西方斯瓦尔克群体，并首次首次，在喜马拉雅前陆盆地东部。沉积记录跨度在西部（Joginder Nagar，Jawalamukhi和Haripur Kolar Sections）中的20至1 Myr分别在东部（Kameng Section）中的13至1 Myr。西部土壤碳酸盐的存在及其在东方的缺失是长期横向气候变异的第一个指示，因为土壤碳酸土壤需要季节性干旱的情况来发展。土壤碳酸盐中的Delta C-13值表现出从西方的千分之一到-2份千分之一到-2份达到-2份的偏移，这是由达到散装有机碳分析的ΔC-13分析的达到7mA同时从大约23份到-19份千分之一。同位素值的这种变化可能与来自C3至C4植被的变化相关联。相比之下，散装有机碳的三角洲C-13值仍然是东部千分之一的23份。因此，我们的数据表明，目前的气候变化在类似于7 mA。我们建议，西方更加季节性气候的区域变化与威斯莱利的影响下降有关，为西部喜马拉雅省提供了更少的冬季降水，而东部仍然潮湿，因为它靠近季风湿度来源。 （c）2017年Elsevier B.V.保留所有权利。

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