C ampos

Potential Source-Rocks

Base of Continental Margin

As depicted on this tentative geological interpretation of a Canvas auto trace of a seismic line of Brazil offshore, the source-rock interval of Campos deep offshore, as well as in almost all the offshores of eastern Brazil, are the lacustrine shales of the Lagoa Feia formation, which are, strictly, associated with saline environment which allowed the deposit of evaporite series, which in the deep parts cover them almost completely. These shales (sensu stricto) are located, immediately, above rift-type basins, i.e., at the base of the Atlantic-type divergent margin, below the salt interval or associated salt welds. i.e., below the salt induced tectonic disharmony. As they postdate the breakup unconformity (BUU), they can be deposited, directly, above the rift-type sediments or over the volcanic crust. In this particularly case, eastward of the basement buried hill, they lie above the SDRs (sub-aerial lava flows or sub-aerial volcanic crust) and then, directly, above the oceanic crust. To better understand the proposed tentative geological interpretation, correct, even mentally, the geometry of the salt induced tectonic disharmony, i.e., imagine a depth version of the autotrace taking into account, mainly, the abrupt changes in water depth.

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