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The MacKenzie delta is the most exciting petroleum exploration area in North America. It is situated at the confluence of three orogenic belts: the north-trending Richardson Mountains; the northwest-trending British and Barnes Mountains; and the northeast-trending Aklavik arch-Campbell uplift. Within the delta are local and regional structures which correspond in strike to all 3 of these tectonic trends. A recently completed, extensive gravity survey clearly reveals these structures.
The main tectonic elements of the delta from the gravity data are: a large northeast-trending basement high and parallel system of growth faults that bound the delta on the east; the adjoining northeast-trending Kugmallit trough; the Campbell uplift on the southeast margin of the delta; the Aklavik-Tunnunuk arch; a regional basement high in the Beaufort Sea parallel with the coast; large, northwest-trending, anticlinal folds; faults bounding the major positive structures; and probably diapirs.
The present delta was a Cretaceous depocenter. Cretaceous sandstones, shales, and conglomerates thicken abruptly across faults into the Kugmallit trough. Oil and gas discoveries to date in the delta are from Cretaceous and Cretaceous-Tertiary sandstones on structures indicated by pronounced gravity maxima. However, Paleozoic rocks may be at drillable depths on some of the structures and are possible objectives. Numerous, very large structures prospective for hydrocarbons delineated by gravity data are of 4 types: (1) regional arch (regional gravity maximum); (2) large, linear fold, with a dense core (large linear gravity maximum); (3) large linear fold, with a low-density core (relatively small gravity maximum); and (4) probable diapirs (round to oval gravity minima).
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