--> Occurrence of Authigenic Carbonate Chimneys and Crusts in the Campos Basin Continental Slope - SE Brazil, Miller, Dennis J.; Kowsmann, Renato O., #90100 (2009)

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Occurrence of Authigenic Carbonate Chimneys and Crusts in the Campos Basin Continental Slope - SE Brazil

Miller, Dennis J.1
 Kowsmann, Renato O.1

1Cenpes, Petrobras, Rio de Janeiro, Brazil.

Several authigenic carbonate accumulations have been found outcropping on the Campos Basin continental slope. These accumulations were discovered during Remotely Operated Vehicle (R.O.V.) dives for deepwater environmental studies and for seafloor production facilities site inspections. The authigenic carbonates occur mainly in the form of chimneys and crusts, also being found as blocks, nodules and fragments of varying shapes and sizes in water depths ranging approximately from 1100 to 1780 meters. Their composition is dominantly dolomitic, having carbonate bioclasts, clays, quartz and feldspars as secondary and trace components.

Carbon isotopic values for these carbonates are not consistent with values from well-documented hydrocarbon seep areas. However the presence of both oil inclusions in carbonate samples and bitumen aggregates at one of the sites suggests that the carbon used for the microbially mediated precipitation of the authigenic carbonates has probably a thermogenic component.


AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil