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This is the Home Page of a large abstract of a conference presented in Tenth Annual Research Conference, Gulf Foundation, which took place Adam's Mark Hotel, Houston, Texas, December 10-13, 1989.

If you click on the interlinks (underlined text and bots), you can navigate and you will find a text and the majority of the plates shown during these conference.

In Kwanza-Congo basin, there are mainly two types of salt welds: (i) Primary salt welds and (ii) Secondary salt welds. Tertiary salt welds are rare, but quite frequents in certain salt basins, as, for instance, in Gulf of Mexico. Primary welds join strata originally separated by autochthonous salt. The welds are generally gently dipping. Joining regional dipping sub-salt strata with supra-salt sediments (overburden), which, locally, dip more steeply, creates a tectonic disharmony, which may look like an angular unconformity. Secondary salt welds join strata originally separated by steep-sided salt diapirs (walls, stocks, etc.). They are near vertical or are steeply dipping. The salt feeding a spreading bulb or allochthonous sheet causes the diapir stem to laterally shrink : (a) eventually thinning to negligible width or (ii) pinching off entirely, often by varying amounts of contraction. Tertiary salt welds join strata, originally, separated by a first order or higher allochthonous salt sheet (canopies, tongues, nappes, sills, etc.). Salt weld should not be confounded with fault welds ("cicatrices salifères", of the old french geoscientists having work in Angola onshore), which are fault surfaced or fault zones joining strata originally separated by autochthonous or allochthonous salt. A fault weld is equivalent to a salt weld along which there has been significant slip or shear. The cover flanking each side of a diapir can then join discordantly together because diapiric growth is usually asymmetric. In such case, the salt weld resembles a growth-fault whether or not such a fault localized the formation of the diapir. On this tentative geological interpretation of a seismic line from the Congo offshore, a primary salt weld is obvious. At the bottom of the supra-salt sediments, the antiform structures (blue colours) are pseudo turtle-backs, since any significant tectonic inversion took place in their structural evolution. They are associated with a salt flowage or with rafting. In fact, the dips are, locally, enhanced by rotation due either to listric faulting or salt withdrawal below lapouts. As you can see, two main pitfalls are produced by this process : (i) Apparent downlaps (see next plate) and (ii) Pseudo turtle-back structures.

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Seismic Recognition of Salt Welds in Salt Tectonic Regimes

Jackson, M.P.A. & Cramez C.