The Peten area of Guatemala was intermittently occupied by a marine basin from the late Paleozoic through the Cenozoic. The oldest sediments in the basin probably represent deep-water deposition in Pennsylvanian time. Emergence of the area, in the Permian resulted in the deposition of limestones, dolomites, sandstones, and siltstones. Total emergence by the end of the Permian continued through the Triassic and most of Jurassic. Upper Jurassic encroachment

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by the western sea resulted in deposition of red sandstones and conglomerates that lensed out on the positive eastern portion of the area. Resubmergence in the Lower Cretaceous accompanied by east-west faulting divided the area into a deeper southern structural element and a northern platform. Carbonate deposition was almost continuous for the southern element throughout the Cretaceous although embayments contemporaneous with the first stages of submergence resulted in local evaporite development. An extensive evaporite basin existed during the Lower Cretaceous in the shallower and stiller seas of the northern platform. Continued submergence in Middle and Upper Cretaceous resulted in the carbonate covering of the evaporite sequences. Continued deepening and turbidity during the Eocene resulted in the deposition of silty limestones, siltstones, and shales. A general re-emergence at the end of the Eocene is marked by localized occurrences of Oligocene and Miocene limestones and clastic sediments.

The Maya mountains are a positive element that remained static following the late Permian-Triassic emergence. Between the Maya mountains and the northern platform of the Peten lies the Chuquibul embayment, and area that may be of importance for the stratigraphic accumulation of oil.

The basin is buttressed southward by the Santa Cruz Mountains, and east-west Paleozoic range. In front of the mountains lies the Alta Verapaz thrust zone, the effect of Tertiary forces, terminating in an arcuate front extending across the southern portion of the Peten basin.

The southeast end of the Bartlett Deep is represented by Lake Izabel within the basin, and the shore areas of this trough have been filled with a great thickness of Upper Cenozoic sediments.

Oil impregnated rocks, in outcrop and in well cuttings have been found throughout the Cretaceous section and further accumulation is considered likely in the Jurassic redbeds and Permian limestones.

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