The Paramirim Aulacogen

摘要: The Paramirim aulacogen occupies the region of northern Sao Francisco craton that extends from Espinhaco range to a large plateau known as Chapada Diamantina in northeastern Brazilian state Bahia. Corresponding long-lived and partially inverted rift-sag basin, hosts exposes most complete section cratonic cover complex accumulated between Statherian Edicaran periods. sedimentary volcanic rocks basin fill successions are grouped into two major lithostratigraphic units, supergroups. Exhibiting remarkable facies differentiation their occurrences range, on west, Diamantina, east, these units associated with granitic rocks, well Statherian, Calymmian Tonian mafic dykes sills. Supergroup comprises five unconformity bounded sequences, which record alternating mechanical flexural subsidence pulses took place 1775 900 Ma. Frankly dominated by quartz-rich sandstones, deposited alluvial, aeolian shallow marine systems, supergroup reflects continuous recycling sediments depocenters aulacogen. Neoproterozoic is composed three distinct 500 Ma, among them glaciogenic Bebedouro Formation carbonates pelites Salitre Formation. overall geologic architecture structures generated during its contractional inversion Edicaran/Cambrian boundary. regional structure corresponds NNW-trending basement cored uplift, flanked both sides systems reverse faults, thrusts, folds, strike-slip shear zones. Structures related generation processes preserved only small area central segment dominant NNW-oriented fabric elements interact or overprinted E–W-trending southern ends These represent Brasiliano orogenic fronts propagated marginal belts toward interior.