黄土沉积与地球圈层相互作用

LOESS DEPOSITS AND ITS RELATIONSHIP WITH EARTH SPHERE INTERACTIONS

黄土是地球上分布最为广泛的沉积物之一,黄土的分布区也是旱作农业起源地和古文明的发祥地,养育了地球上数以亿计的人口。作为一种风力搬运的沉积物,黄土也是古气候变化的重要信息载体。长期以来,中外科学家已经对黄土的物理学、地球化学、沉积学、古气候学等开展了多学科的综合研究,取得了瞩目的成就。本文旨在从地球系统科学角度出发,将黄土物质的产生、搬运、堆积及沉积后的成土过程与地球岩石圈、水圈(包括冰冻圈)、大气圈、生物圈的演化联系起来,将黄土作为一个窗口,揭示出看似单一的地质事件(黄土沉积)与地球圈层相互作用之间的内在关联。

Loess is one of the most widespread deposits in the world.Loess areas are also famous for early agriculture and ancient civilization.More than hundreds of millions of people now live in loess regions.As airborne dust,loess is also a good geological archive for paleoclimatic variations.To date,many aspects of loess,including physics,geochemistry,sedimentology,paleoclimatology,have been well-studied.The objective of this paper aims to use the theory of Earth System Science,to link the multiple processes of loess production,transportation,accumulation and post-depositional alterations to changes of Earth's spheres.The production of loess-sized materials is closely related to the bedrock denudation of mountains of lithosphere,especially during the glacial time when glacial grinding and frost weathering processes are significant.The dust transportations are associated with the atmospheric circulations which are in turn affected by geomorphology of lithosphere,extent of cryosphere,and land/sea distributions of hydrosphere and lithosphere.The post-deposition processes of loess are closely linked with the climatic changes of atmosphere,geomorphological feature of lithosphere,and vegetation cover of biosphere.Therefore,as a case study,it reveals the intrinsic association between a single geological event(loess deposition)and the Earth's sphere interactions.