The Bresse and Valence salt basins are in two adjacent segments of the West European Rift that cuts across the eastern part of France. They contain thick Paleogene halite sequences including intercalated and interfingering siliciclastic beds and carbonate and sulfate deposits. Source-rock samples were taken mainly from the depocenters because of maximum sampling coverage. Organic matter is generally immature and occurs primarily within intercalated nonhalitic beds. The amount of organic matter varies considerably with stratigraphic location and lithology. The Bresse basin contains organic matter in (1) the Intermediate Salt Fm (Priabonian), composed of alternating laminated carbonate and primary halite beds; (2) the upper part of the upper Salt Fm (brecciated clayey carbo ate beds (Rupelian), affected by multistage halite solution penecontemporaneous with deposition; and (3) the solution breccia that immediately overlies the salt sequence. In the Valence basin, the layers richest in organic matter are in the Subsalt Fm (carbonate beds that are commonly laminated; Priabonian) and the upper part of the Lower Salt Fm (laminites; Rupelian). In both basins, type III kerogen is closely related to terrigenous material. Type I organic matter is abundant in the Valence basin (laminites). Type II seems to be more abundant in the Bresse basin, but its diagnosis remains uncertain. The main depositional environment favoring the preservation of organic matter is likely related to deposition beneath perennially stratified layers of water. Major salt-solution phenomena, hich are evident, are supposed to be responsible for concentration of significant amounts of organic matter concurrently with the accumulation of nonsoluble, brecciated residues.

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