LATE CENOZOIC DEPOSITIONAL HISTORY OF THE WESTERN SVALBARD CONTINENTAL-SHELF, CONTROLLED BY SUBSIDENCE AND CLIMATE

Based on a grid of high resolution, single channel seismic lines, this paper addresses the Late Cenozoic evolution of the western Svalbard c ontinental shelf. The seismic structure of the shelf includes at least 16 erosional unconformities, each representing a glacial advance. The evolution during the last approximately one million years has been di vided into six main erosional and depositional phases. Differential ma rgin subsidence around a hinge zone is an important controlling mechan ism for the accumulation of the sedimentary wedge at the outer shelf. The most significant depositional change appears to be related to a ge neral climatic shift, globally recorded to be centred around 1 Ma. At this level, corresponding to the Upper Regional Unconformity (URU) on the shelf, the depositional regime changed from net erosion to net dep osition and shelf aggradation. Of major significance is probably a shi ft from thick, eroding glaciers with steep ice profiles, to low profil e fast flowing ice streams maintained by an increased amount of interg lacial and interstadial sediments. The relationship between climatic f luctuations, glacial dynamics and depositional regime is discussed.