861-882－Marine al flows initiation, behavior and related deposits. A review.pdf

Marine al ?ows: initiation, behaviorand related deposits. A reviewThierry Muldera,*, James . Syvitskib,Se′bastien Migeonc,Jean-Claude Fauge`resa, Bruno SavoyedaDe′partement de Ge′ologie et d’Oce′anographie, UMR 5805 EPOC, Universite′Bordeaux I, Avenue des Faculte′s, 33405 Talence cedex, FrancebDepartment of Geological Sciences and Institute of Arctic and Alpine Research, University of Colorado, Box 450, Boulder, CO 80309-0450, USAcGeological Survey of Canada Atlantic, Bedford Institute of Oceanography, . Box 1000, Dartmouth, NS, Canada B2Y4A2dIFREMER, DRO/GM, BP 70 29280 Plouzane′, FranceReceived 1 July 2002; accepted 9 January al ?ows form in the marine environment when river discharge enters the ocean with suspended concentrations in excess of36 kg m23due to buoyancy considerations, or as little as 1–5 kg m23when convective instability is considered. They form at a river mouthduring ?oods of small to medium size rivers including extreme events such as jo¨kulhaups, dam breaking and draining, and lahars. Associatedwith high-suspended concentration, they can transport considerable volume of sediment to ocean basins. The typical deposit or itesequence is pound of a basal coarsening-up unit, deposited during the waxing period of discharge, and a top ?ning-up unit depositedduring the waning period of discharge. ites differ from other turbidites because of their well-developed inversely graded facies andintrasequence erosional contacts. These observations lead to plete rede?nition and interpretation of ?ne-grained stacking can locally generate high-sedimentation rates, in the range of 1–2 mper 100 year. Because ites are relatedto climate through ?ood frequency and magnitude, their record should vary with sea level and climate change. They can also be associatedwith proximal ice-melting settings. al ?ows could also be involved in the formation of meandering canyons and Elsevier Ltd. All rights :al ?ows; River load; C