The geochemical characteristics and geodynamic meaning of Yaupi Member of the Chapiza Formation, in the Cutucú Cordillera

Abstract

To southeast of the Cordillera Cutucú, in the Yaupi river, the Emarcadero to Yaupi section allows identification and characterization of Yaupi Member (Lower Cretaceous) of the Chapiza Formation (Middle Jurassic – Lower Cretaceous). Yaupi Member includes sandy siltstones with volcanic clasts and organic material (LAM), cross-stratification arkose, massive lithic sandstone with volcanic clasts, matrix-supported breccia with normal gradation, crystal-tuff with glass-shard and graded lithic-tuff, porphyritic andesites and massive, monomictic, clast-supported breccia. Low sorting, low roundness and low sphericity observed in the sample set indicates immature character of the detritus. Accordingly, the Yaupi Member was deposited in alluvial fans proximal to an active volcanic source. Petrographic and geochemical sandstone set data indicate that Yaupi Member facies were deposited in active continental margen, in response to erosion from intermediate to felsic igneous province proximal. Geochemical data characterize volcanic rocks such as andesites and basaltic andesites, calco-alkaline affinity, typical of intra-continental domain.