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ORIGEM DOS DEPÓSITOS DE AREIAS BRANCAS NO NORDESTE DO AMAZONAS

2003; Sociedade Brasileira de Geologia; Volume: 33; Issue: 1 Linguagem: Inglês

10.25249/0375-7536.20033314150

2177-4382

Adriana Maria Coimbra Horbe, Marco Antônio Horbe, Kenitiro Suguío,

Soil Management and Crop Yield

The present analysis on the white sand deposits in northeastern Amazonas States Brazil), shows that they are subdivided in three horizons named A, B and C. The superficial horizon (A) is composed of friable sandy materials, white to gray with organic matter accumulations as wavy bands. The B horizon is essentially sandy, yellow to orange. The C horizon is made up of sandy argillaceous material, rich in kaolinite, Al 2 O 3 , Fe 2 O 3 and TiO 2 . Organic matter material, forming "ortsteins" is present in the contact zone between the horizons B and C. The above profile along with quartz grain corrosion in the uppermost horizon, and kaolinite-rich C horizon, suggest that the white sand deposits are relate to podzolic processes with differentiation of horizons and accumulation of organic matter generated by decomposition of forest litter forming Spodosols. These data relate the Spodosols to truncated profiles and, thus, their formation from the rich quartz-saprolitic horizon of the Alter do Chão Formation. This process of podzolization, that continues to the present, is very aggressive, as the studies profiles have developed in less than 3,000 years under modern forest cover.