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FORMAÇÃO IAPÓ: GLACIAÇÃO CONTINENTAL NO LIMITE ORDOVICIANO/SILURIANO DA BACIA DO PARANÁ

1998; Sociedade Brasileira de Geologia; Volume: 28; Issue: 1 Linguagem: Inglês

10.25249/0375-7536.19985160

2177-4382

Mário Luís Assine, CARLOS J. S. ALVARENGA, JOSÉ ALEXANDRE J. PERINOTTO,

PARANÁ BAS1N.The lapó Formation is a thin and widespread unit, generally less than 20 m thick and covering discontinuously an área of hundreds of thousand square kilometers.The main fácies is massivê diamictites, which display pebbles and cobbles in a mud matrix, some of them faceted and striated.The massive diamictites are considered subglacial tillites.The fácies association includes stratified diamictites, conglomerates, massive and stratified sandstones, and fine laminated fácies with dropstones.The glaciation in the Ordovician/Silurian boundary is well constrained and its correlation with other Gondwanan basins suggests maximum glacial in the Iate Ashgillian age.The lapó Formation is overlain by early Llandovery post-glacial transgressive shales of the Vila Maria Formation.It is herein proposed a modcl of glaciomarine stratigraphic architecture in a glaciated continental margin to explain the origin of the lapó Formation.