Anais do XXXIV Congresso Brasileiro de Ciência do Solo

Clay mineral formation and porosity development during 120 ky weathering of Bishop Creek granodiorite

LAURENT CANER⁽¹⁾; PAUL SARDINI⁽¹⁾; MARJA SIITARI-KAUPPI⁽²⁾; KARL-HEINZ HELLMUTH⁽³⁾; ROBERT C. GRAHAM⁽⁴⁾; ARNAUD MAZURIER⁽⁵⁾;
1 - UNIVERSITY OF POITIERS; 2 - UNIVERSITY OF HELSINKI; 3 - STUK; 4 - UNIV. OF CALIFORNIA; 5 - SOCIÉTÉ ETUDES RECHERCHES MATÉRIAUX;

The development of porosity is a key factor of rock weathering that control water flow and water-rock interactions. The objective of this work is to quantify porosity formation of granodiorite boulders with increasing weathering by impregnation with 14C labeled resin (MMA), autoradiography and image analysis, along with chemical and mineralogical analyses. The results show that dissolution of feldspars is responsible of cavity formation while biotite expansion produces angular cracks. With increasing weathering aperture of the pores increase and clay minerals formed by weathering of biotite and plagioclases partly fill the porosity. Index terms: alteration, porosity maps

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