Timing of canyon-fed turbidite deposition in a rifted basin: The Early Cretaceous turbidite complex of the Cerrajon Formation (Subbetic, Southern Spain)

摘要

The Subbetic Cerrajon Formation of latest Hauterivian-earliest Late Albian age is made up of turbidite sandstones and calcarenites intercalated in marly-limestones and marls. It can be defined as a turbidite complex with three distinct intervals where turbidites are recorded: latest Hauterivian-Barremian p.p., Late Aptian p.p. and Middle to middle-late Albian age. The distribution of four biochronostratigraphic units of these ages throughout the studied outcrops is shown. The main hiatuses, latest Barremian-early Late Aptian and latest Aptian-early Late Albian, mainly the latter, have been identified in many other outcrops of the Southern Tethys, and are related to tectonics and associated palaeogeographic and palaeoceanographic changes. Platform environments, as the source area of the clastics, the feeding submarine canyon, base-of-slope channels and related basinal lobes or sheet systems, have been identified and can be traced laterally along more than 80 km of discontinuous outcrops aligned in a downcurrent direction. The system could have extended more than 150 km in length. The mean palaeocurrent direction fits well with the present alignment of the outcrops and, after corrections for tectonics rotation, with the current palaeogeographic model of the Southern Iberian Continental Palaeomargin (SICP). This conclusion largely supports previous interpretations of a longitudinal pattern for the distribution of elastics during the Cretaceous in that part of the SICP. The ages of the main Cretaceous events deduced from the study of the Cerrajon Formation correlate quite well with the sequence sets and subsidence history of the Prebetic Zone, where the Cretaceous platform environments adjacent to the turbidite basin are recorded. Moreover, the main unconformities dated, such as the onset and the end of turbidite sedimentation, show good correlation with the sequence boundaries described for the European basins. The analysis in time and space of the turbidite distribution and its correlation with the Prebetic carbonate platforms enables us to outline some interesting conclusion that might be a suitable subject for future research.