Corozal Basin Stratigraphy of Northern and Central Belize
Wade, Mandela; King Jr, David T.; Petruny, Lucille W.
Corozal Basin stratigraphy consists of a (1) thick section of deformed and metamorphosed Carboniferous-Permian sedimentary and volcanic strata in the Maya Mountains, (2) moderately thick section of Mesozoic strata, mostly carbonates, which are found in the subsurface and in outcrop near the Maya Mountains and along major faults, and (3) relatively thin section of Paleocene-Pleistocene carbonates. There is a substantial regional unconformity separating pre- and post-Mesozoic strata. The Mesozoic-Cenozoic stratigraphic section of the Belize coastal plain has a moderately well-developed disconformity-bounded sequence stratigraphy. Recently renewed onshore petroleum exploration efforts in this part of Belize have indicated the presence of a mature source rock from North Peten Basin, a possible source for shows, seeps, and live oil shows in the Corozal. Ongoing geological and geophysical analyses have shown that small scale, Cretaceous-Paleogene anticlinal and fault-related features are important productive petroleum traps. The trend of these structures is north-northeast to south-southwest, but the trend changes to more nearly east-northeast to west-southwest as these structures draw near to the Maya Mountains. The petroleum bearing units are the Hill Bank and Yalbac, but petroleum may reside in overlying units (Barton Creek and El Cayo carbonates) as well. The Hill Bank, mainly dolomite, generally thickens from the northern flank of the Maya Mountains to the northwest from 250 to 650 ft. The overlying Yalbac, a series of alternating dolomite and anhydrite facies, thickens from a few hundred feet to 8,000 feet towards the northwest. Recent exploration wells have indicated that the mid-Yalbac Y2 interval appears as the most prospective reservoir unit with porosity values ranging from 10-15, and up to 30 percent. Reservoir properties become more favorable to the northwest where there are thicker prospective intervals and increased porosity capped by increased anhydrite layers. Seismic, aeromagnetic, and gravity data support the interpretation for basement-related, small scale anticlinal and fault structures in the Corozal. There is also the potential for stratigraphic traps where Paleozoic sections are truncated by Mesozoic-Cenozoic stratigraphic section.
AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013