Análise faciológica da Formação Alter do Chão próximo a cidade Vitória do Jari (AP), Bacia do Amazonas

Abstract

The palaeoenvironmental reconstruction of Formation Alter do Chão (Upper Cretaceous/Lower Tertiary), Basin Amazonas, around city Vitória do Jari, be grounded principally features facies, as: geometry sedimentary packges and its structure sedimentary, as vertical and lateral relation. These deposits consist of sedimentary bodies, concave geometry , bounded for polymictic conglomerates in the pebble of quartz, and thick sandstone, kaolinized fragment, under of thick and average sandstone, with tabular cross bedding, acanalada and trough cross-bedding to form in cycles of finning upward, what change laterally for bodies tabular of fine and average sandstones. Under and bounded for erosive surface occurs heterolithic beddings characterized for red mudstone, lamination parallel, interleaved for average sandstone with tabular cross bedding. Laterally its bodies integrate with laminated mudstone of tabular geometry. This form its change of center channel deposits for tabular bodies quartz composition, with average and big postage tabular cross bedding predominantly, featuring point bar deposits, whose origin are related with migration continuous of sandy form. Corporatly occurs bars downstream with big lateral extension similar to described previously, however its are organizes on red mudstone, with cross bedding parallel plane and block texture. The system meandering river channel is interpreted as depositional environment. The cyclicatly facies, geometry of sedimentary packages and the big lateral extension theses deposits reinforce this interpretation.