Facies successions in the pre-evaporitic Late Miocene of the Lorca Basin, SE Spain

Pre-evaporitic uppermost Tortonian to Messinian carbonate-siliciclastic dep osits have been studied in the western part of the Lorca Basin. Individual lithofacies, facies associations as well as facies successions and stratal architecture indicate a gravel-rich fluvial-dominated (Gilbert-type) delta environment. During periods of decreasing terrigenous supply carbonate sedi mentation predominated including formation of patch reefs and fringing reef s. The observed progradational stacking pattern of facies successions is at tributed to a '3rd-order' eustatic highstand that pre-dates the Messinian l owstand evaporites of the well known 'salinity crisis'. Five facies success ions have been recognized. Each succession is composed of three facies asso ciations that are: mixed carbonate-siliciclastic (mcs), carbonate-dominated (cd) and siliciclastic-dominated (sd). They show retrogradation-aggradatio n-progradation architecture and represent '4th-order' transgressive-regress ive cycles. The five successions can be correlated through the whole basin and are interpreted as a useful tool for basinwide sequence stratigraphic c orrelation. If in addition, other recently published data from SE Spain are considered it may turn out that future correlations between different Neog ene basins at this cycle scale ('4th-order') will be possible. Higher-frequ ency successions or cycles at a bed or bedset scale ('5th- or higher order' ) are noticeable but are clearly related to local depositional processes (f acies dynamics). They do not have any significance for a basinwide sequence stratigraphic correlation. (C) 1999 Elsevier Science B.V. All rights reser ved.