FÁCIES SEDIMENTARES E SISTEMAS DEPOSICIONAIS DAS FORMAÇÕES ALTO GARÇAS E VILA MARIA

Revista Brasileira de Geociências

29(3):419-428, setembro de 1999

FÁCIES SEDIMENTARES E SISTEMAS DEPOSICIONAIS DAS FORMAÇÕES ALTO
GARÇAS E VILA MARIA NA REGIÃO DE CHAPADA DOS GUIMARÃES (MT),
BORDA NOROESTE DA BACIA DO PARANÁ
MARCIO IVAN CARVALHO MOREIRA & LEONARDO BORGHI
ABSTRACT SEDIMENTARY FACIES AND DEPOSITIONAL SYSTEMS OF THE ALTO GARÇAS AND VILA MARIA FORMATIONS
IN THE CHAPADA DOS GUIMARAES REGION (MT), NORTHWESTERN BORDER OF THE PARANA BASIN The Ordovician-Silurian interval of the Paraná Basin, outcropping in the Chapada dos Guimarães, Campo Verde and Santo Antonio do Leverger counties (MT), is represented by the Alto Garças and Vila Maria formations. This interval is characterized by sixteen lithofacies and two ichnofacies. Among these lithofacies, nine ruditics, six arenitics and one lutitic are identified. The ruditics lithofacies are named massive conglomerate (Cm), conglomerate in tabular beds (Ct), conglomerates and sandstones interbedded in tabular beds (Ct(H)), conglomerate with cross-stratification (Cc), massive diamictite (Dmm), massive diamictite with evidence ofressedimentation (Dmm(r)), stratified diamictite (Dms), stratifieddiamictite with evidence of current reworking (Dms(c)) and stratified diamictite with evidence of ressedimentation (Dms(r)); the arenitics ones are named massive sandstone (Am), sandstone in tabular beds (At), sandstone with climbing-ripple cross-lamination (Acl), sandstone with cross-stratification
(Ac2), sandstone with ripple cross-lamination (Ao) and sandstones and shales interbedded inflaser, wavy and linsen bedding (Ao(H)); and finally the lutitic lithofacies is named shale with dropstone (Fid). The identified ichnofacies are Skolithos (Sko), by the presence of Skolithos linearis, Arenicolites ichnosp. and Diplocraterion ichnosp., and Cruziana (Crz), by the presence of Arthrophycus alleghaniensis, Palaeophycus tubularis, Aulichnites ichnosp., Lockeia ichnosp., Chondrites ichnosp. and Teichichnus