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The development of a passive margin involves a sequence of thermally induced events lasting about 100 m.y. before reaching maturity, when sediment accumulation responds to subsidence related to cooling of the lithosphere. This early sequence of events includes arching and uplift with erosion and shedding of sediment to the adjacent continental interiors, rifting with associated lacustrine and fluvial sedimentation, potential evaporite deposition, development of a narrow ocean with potential for restricted circulation, and subsidence of marginal shelves to sea level with reversal of drainage recycling large volumes of previously offloaded sediment onto the young margin. The northern margin of the Gulf of Mexico is unique among passive margins in that critical phases of its development coincide with the Cretaceous highstand of sea level and overriding of Pacific spreading centers by the North American continent. The Cretaceous sea level maximum coincided with the phase of early subsidence which should have caused reversal of interior drainage and rapid sedimentation
on the margin. The result was to store sediment in the continental interior until much later in the development of the margin. Cenozoic sea level decline coincided with the interaction of North America and Pacific spreading centers focusing anomalously large volumes of sediment on the northern Gulf margin. The only other passive margins with similar timing and which might have a similar history are those associated with the initial splitting of Gondwanaland.
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