About this Item
Sequence-stratigraphic models conceptualize the deposition of genetically related sediment packages along continental margins as a response to various phases of the cycle of relative change of sea level. Regional tectonics (subsidence/uplift), eustasy, and rate of sediment supply interact to produce the measure of relative change of sea level. During a complete cycle of sea-level change, characteristic stratal patterns resulting within siliciclastic systems comprise: a basal, basinward prograding wedge of lowstand (or shelf-margin) systems tract; an intermediate, retrogradational landward back-stepping, transgressive systems tract; and an upper, aggrading to prograding, highstand systems tract. In siliciclastic systems most of the terrigenous material is delivered to the basin during the lowstand. Stratal patterns in carbonate systems are comparable to those in the siliciclastic systems; much of the carbonate is transferred to the basin during lowstand progradation. However, carbonate can also be exported off-bank during late highstand, when productivity on the bank top is high while accommodation is reduced. Both lowstand and late highstand progradation contribute to lateral growth of the platform. In hybrid siliciclastic carbonate systems, lowstands may be dominated by clastic deposition, while carbonate accumulation may occur both during lowstand and highstand times. The history of the development of the basic conceptual framework of sequence stratigraphy, and the efforts that led to the documentation of sea-level variations deciphered from sequence analysis of subsurface and outcrop data, is outlined. The resulting history of sea-level change and its relationship to the sedimentary patterns of the deep sea are also discussed. A climatic feedback model of an alternating erosive/corrosive response to sea-level fall and rise is offered. Erosion on the sea floor is dominant during low sea-stands, and canyon incision on the margins during major falls of sea level. Carbonate dissolution on the sea floor is enhanced during times of maximum flooding of the shelves and during early highstand when carbonate is conserved on the inner shelves and nearshore. During the late highstand phase, following reduced accommodation on the banks, carbonate is again exported to the basins, abating the corrosive cycle. Distinction between early and late highstand phases, and between late highstand and lowstand progradation is, therefore, critical to understanding the response of the carbonate system and deep-sea sedimentary patterns to sea-level change along continental margins. 37 pp. 16 figs, 1 tab., gr. 8.
Seller Inventory # W36008
Contact seller
Report this item
