Palygorskite in palaeosols from the Miocene Xiacaowan Formation of Jiangsu and Anhui Provinces, P.R. China

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• 作者：Long ; D.G.F. ; McDonald ; A.M. ; Yi ; Facheng ; Li ; Houjei ; Zheng ; Zili ; Tian ; Xu
• 关键词：soil ; weathering ; palygorskite ; montmorillonite ; ephemeral alkali lakes ; basalt ; Tertiary ; China
• 刊名：Sedimentary Geology
• 出版年：1997
• 出版时间：September, 1997
• 年：1997
• 卷：112
• 期：3-4
• 页码：281-295
• 全文大小：1.89 M

文摘

Strata associated with Tertiary basalts of the Xiacaowan Formation, in the North Jiangsu Basin of eastern China, contain mudstones which are rich in palygorskite and montmorillonite, with lesser concentrations of dolomite and CT-opal. Massive montmorillonite clays may have developed as vertisols by deep meteoric weathering of underlying basalt flows in a sub-humid to semi-arid climatic setting with pronounced seasonality. Laminated montmorillonite clays, higher in the sequence, accumulated in low-lying areas in inland lakes with poor external drainage. Climatic fluctuations resulted in periods of increased aridity, during which falling lake levels exposed montmorillonite-rich vertisols, lake and playa sediments, to further pedogensis. Lowering of the water table and increased rates of evaporation allowed leaching of sodium and calcium from the soils; this, in conjunction with the introduction of silica and magnesium by rising ground water, led to the neomorphic development of extensive stratiform palygorskite deposits.