SEDIMENTARY FACIES AND DEPOSITIONAL ARCHITECTURE OF ICE-CONTACT GLACIOMARINE SYSTEMS

The characteristics of ice-contact glaciomarine systems are reviewed, based on a range of Weichselian and Holocene examples from the fjordal basins in Norway and Svalbard. These depositional systems occur as la rge morphological ridges, ''end-moraines'' (including ''push-moraines' '), which are coarse grained and show large-scale foreset bedding. The paper addresses some of the major problems with regard to the recogni tion, classification and stratigraphic analysis of these systems. The ice-proximal glaciomarine systems are classified here into three categ ories: (1) ice-contact submarine fans, (2) ice-contact deltas and (3) glaciofluvial deltas. This classification integrates morphological and sedimentological criteria, and renders these glaciomarine systems not only easier to recognize in the stratigraphic record but also possibl e to compare with common, non-glacial deltaic systems. The emphasis is on the criteria for the recognition of the ice-contact glaciomarine s ystems (i.e., ice-contact fans and ice-contact deltas) and their discr imination from common Gilbert-type deltas and fan deltas. The review f urther focuses on ice-contact glaciomarine systems as highly sensitive recorders of glacier dynamics and climatic fluctuations. It is shown that both the periods of ice-front ''stability'' and changes in the ic e-front position, as well as the magnitude and rate of those changes, are all recorded in the ice-contact depositional system. The sedimenta ry record further reflects glacio-isostatic sea-level changes and loca l palaeogeography. A new conceptual model is suggested, which places t hese ice-contact glaciomarine systems in a dynamic stratigraphic conte xt. The model integrates sedimentary facies and their depositional arc hitecture in an allostratigraphic framework, and is meant to be a guid e for the analysis of the sedimentary record of ice-contact systems.