SOME ASPECTS OF PALEOWEATHERING IN THE IBERIAN HERCYNIAN MASSIF

作     者：MOLINA, E CANTANO, M VICENTE, MA RODRIGUEZ, PG 

作者机构：Departamento de Geología Fac. Ciencias Univ. Salamanca 37071 Salamanca Spain Inst. Edafología (C.S.I.C.) Serrano 115 28006 Madrid Spain C.E.B.A.S. (C.S.I.C.) Apdo. 257 37071 Salamanca Spain 

出 版 物：《CATENA》 (Catena)

年 卷 期：1990年第17卷第4-5期

页      面：333-346页

核心收录：

学科分类：07[理学] 0708[理学-地球物理学] 0903[农学-农业资源与环境] 0815[工学-水利工程] 

摘      要：The Iberian Hercynian Massif occupies most of the western half of the Iberian Peninsula and forms the basement over which Mesozoic, Cenozoic and Quaternary materials rest unconformably. Over it can be found remains of weathering profiles that are fossilized by marine and/or continental sediments of different ages. On the southwestern border of the Tertiary basin of the Duero and below the series attributed to the lower Tertiary (Palaeocene), lies a weathering mantle that has been displaced by the effects of alpine tectonics. Accordingly, it remains may appear truncated and/or covered by other more recent deposits. The present work studies this ancient weathering mantle in the zones in which it appears developed over the slaty series of the basement in the province of Salamanca, central west Spain. The profiles chosen reveal the existence of a strong chemical weathering that involves the destruction of some primary materials (Fe-bearing chlorites and feldspars) and the formation of kaolinites and Fe-oxihydroxides. The start of the degradation of chlorite occurred during the first weathering phases;this evolved towards an expandible smectite-like mineral. This first phase reflects the disappearance of albite, and chemical analysis points to a pronounced loss of Na. In the most advanced stage the chlorites and smectites have disappeared, giving way to the presence of kaolinite, goethite and hematites. This weathering phase is associated with a strong loss of Mg. The main process occurring in these profiles are monosiallitisation and ferruginisation.