The intracratonic Paris basin, essentially of Mesozoic age, covers approximately 43,000 mi² (110,000 km²); 10,000 ft (3000 m) of strata fill the area of greatest subsidence. The present-day basin is bounded by three major blocks where the Hercynian basement crops out: the Ardennes block on the north, limited by an east-west fault; the Armorican massif on the west; and the Central massif and the Morvan-Burgundy-Vosges arch on the south and east.

The basin originated during the Permo-Triassic extensional phase with the formation of a flat-bottomed trough that was superposed onto the Y-junction of three fault systems. The faults, derived directly from the Hercynian structural framework, are related to Late Carboniferous grabens. The fault systems separate the three major structural basement blocks that bound the present-day basin and can be traced beneath it. A period of rifting accompanied by high thermal gradients took place during Liassic time; rifting was followed by downwarping, possibly caused by thermal subsidence. This period was accompanied by widespread transgression and deposition of organic-rich black shales. Dogger time was characterized by broad carbonate platforms; whereas, during Malm time, primarily argillaceou deposition took place. Most of the Paris basin became emergent near the end of Jurassic time. The sea gradually returned and chalk was deposited during Late Cretaceous time. The Paleogene (Lower Tertiary) sea later overlapped part of the basin.

The Paris basin took its present shape following uplift of the surrounding basement blocks during the Tertiary (Alpine) orogenic events. The same three bordering massifs or blocks were nevertheless active most of the time and influenced, though in a subdued manner, sedimentation and facies distributions.

The present-day basin is a remote appendix of the Triassic German domain to the northeast. It was open to the southeast (Tethyan basin) during the Jurassic and the Early Cretaceous and was subsequently exposed to influences from the North Atlantic and boreal seas from the west and northwest during the Late Cretaceous and the Tertiary. Gradually, it became a slowly subsiding, discrete basin during the Tertiary.

After the major Carboniferous compressional event (Hercynian or Variscan orogeny) and the Permian to Lower Cretaceous extensional period, the basin underwent compressional tectonism during the Alpine orogenic cycle (Upper Cretaceous to present). A weak east-west compressional phase took place during late Albian time, followed by a second north-south compressional phase related to the Pyrenean orogeny between Late Cretaceous and early Eocene. After a short episode of extension during the Oligocene, the Alpine orogeny induced northwest-southeast compression in the southeastern part of the basin. Early anticlines have north-south axes. Younger anticlines occur along genetically related east-west fault systems. More subtle folds have northwest-southeast and northeast-southwest axes. Vario s amounts of strike-slip movement accompanied these compressive episodes and rejuvenated old faults.

In the early 1950s, hydrocarbon exploration began in the Paris basin and passed through two successful phases from 1958 to 1960 and from the early 1980s to the present. The relatively simple oil system stems from mature Liassic-age sapropelic source rocks in the central Paris basin. The reservoirs consist of Middle and Upper Triassic sandstones, Dogger carbonates, and local Neocomian sands sealed by shale. The oils are homogenous, paraffinic, and low in sulfur and gas content. Gravity ranges between 32° and 25° API;

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the lower value is due to bacterial decay. The traps are domes, low-relief anticlines, and stratigraphic pinch-outs, particularly in the Neocomian sands.

To date, slightly more than 40 million tons (280 million bbl) of oil have been found distributed among 50 fields. One small gas pool has also been discovered.