Evolution of the early Paleozoic deep-water basin of north Greenland—Aulacogen or narrow ocean?

Abstract

A major lower Paleozoic deep-water sequence is exposed for more than 800 km along the coast of north Greenland. The maximum preserved width of the basin is about 200 km, and the thickness of the sedimentary sequence may reach 8 km. Nine evolutionary stages in basin evolution are recognized, each characterized by distinct sedimentary facies and structural style of the shelf-basin boundary: (1) the oldest sequence of unknown age is so deformed that inferences about the depositional environment are precluded; (2) late Precambrian(?)-Early Cambrian incipient basin; (3) Early Cambrian narrow turbidite basin; (4) Middle Cambrian-Ordovician basin expansion and initial starvation; (5) latest Ordovician-Early Silurian longitudinally filled turbidite basin; (6) Middle Silurian basin expansion and starvation; (7) Middle-Late Silurian wide turbidite basin; (8) Middle-Late Silurian Caledonian thrusting and conglomerate deposition; and (9) probably latest Silurian megasliding and advance of the Caledonian front. The basin evolution that came to an end during the mid-Paleozoic Ellesmerian orogeny was punctuated by events related to the closure of the Iapetus ocean and formation of the Caledonian mountain belt to the east. The basin may have been fully ensialic and formed during the early rifting stages preceding back-arc spreading, or it may have reached a narrow ocean stage. At present, however, we are inclined to favor an interpretation of the basin as being an aulacogen extending deeply into an old continent at a right angle to the Caledonian orogenic front to the east.