MESOZOIC STRATIGRAPHY AND PALEOENVIRONMENTS OF THE GEORGES BANK BASIN- A CORRELATION OF EXPLORATORY AND COST WELLS

The Exxon 975-1, Conoco 145-1, and Mobil 312-1 hydrocarbon exploratory wells and the Continental Offshore Stratigraphic Test (COST) G-1 and G-2 wells were drilled in the southeastern part of the Georges Bank Ba sin. We used drill cuttings and logs from these wells to describe and correlate the dominant lithostratigraphic units and to document latera l changes in the depositional environments. The strata penetrated by t he Exxon 975-1 and COST G-1 wells are much more terrestrial than at th e seaward (downdip) COST G-2, Conoco 145-1, and Mobil 312-1 wellsites. Oldest rocks penetrated by the exploratory wells represent a Middle J urassic carbonate-evaporite sequence that correlates to the Iroquois F ormation. The Iroquois records nonmarine to marginal-marine sabkha, ti dal-flat, and restricted lagoonal paleoenvironments in the Exxon 975-1 and COST G-1 wells, but progressively changes to inner neritic, litto ral, and lagoonal paleoenvironments at the Mobil 312-1 wellsite. The n onmarine deltaic siliciclastics of the overlying Mohican Formation, Mi saine Shale, and Mic Mac-Mohawk Formations are thicker and the marine carbonates of the Scatarie and Bacarro Limestones are usually thinner in the Jurassic strata of the Exxon 975-1 and COST G-1 wells than at t he other wellsites. Similarly, lower delta-plain and delta-front facie s of the Early Cretaceous Missisuaga and Logan Canyon Formations at th e Exxon 975-1 and COST G-1 wellsites reflect a greater terrestrial inf luence than the laterally-equivalent shallow marine to delta-front fac ies present at the downdip wellsites.