FOSSIL AND RECENT CARBONATE SLOPES SYSTEMS: RULES AND QUESTIONS

The study of fossil and recent submarine slope systems has accelerated recently. In part, this interest is triggered by the boom in the search for hydrocarbons in deeper water turbidite and channel sand systems. New discoveries such as on the off bank transport mechanisms, the recovery of high resolution and complete climate archives in slope systems, the origin of major and repetitive failures of continental slopes due to the presence of gas hydrates as well as its potential economic value, and the relationship with oceanographic conditions, also contribute to this trend. Research on fossil and recent slope systems has provided some fundamental rules on the relationship between slope morphology, sediment composition and, to a certain extent, depositional processes that were successfully applied in slope studies. However, they do not explain Late Paleozoic high rising and steep carbonate slopes dominated by boundstone, the observed evolutionary steepening of carbonate slopes, or the major collapse of many carbonate margins. Nor do they provide reliable estimates on sediment composition in exponential slopes or, visa versa; allow the prediction of margin geometries from observations on composition and texture alone. This current shortage of knowledge is, in part, related to the limited access to integrated and high quality data on intact slope systems. Marine seismic data provide information on stratal anatomy but lack continuous observations of sediment composition and smaller scale spatial variation of sediment anatomy. Visa versa, outcrops allow continuous observations but complete and intact slopes are rare. A strategy that integrates sedimentological and petrophysical slope parameters in fossil and recent slope systems is needed to advance our understanding of slope environments. Modern high-resolution 3D seismic data need to be combined with shallow multi-well transacts across recent active slope systems. Similarly, intact and complete outcrops of seismic-scale slopes need quantification of sediment anatomy, stratal patterns and texture using modern field techniques that include deployment of DGPS systems. Only such an integrated approach through “natural laboratories” can provide reliable slope models that have predictive value for economic and academic exploration.