In the NE Iberian Plate, the convergent motion and collision of the European, Iberian and African plates resulted in the development of Paleogene compressional features (strike-slip systems, thrust-fold belts) and late Oligocene to mainly Neogene extensional structures which are superimposed on the former. These extensional structures are represented by horsts, half grabens and tilted blocks, often developed in connection with preexisting, inherited faults. From the late Oligocene and during the Neogene both strike-slip and extensional regimes alternated and coexisted, giving rise to a number of fault-bounded basins. The deposition of organic-rich facies, and in particular oil-shales, took place in the lacustrine complexes developed in some of these basins: Campins Basin (late Oligocene); Ribesalbes and Rubielos de Mora basins (early-middle Miocene); Libros Basin (late Miocene) and Cerdanya Basin (late Miocene). Deep lacustrine sequences ranging from 100 up to 250 m thick were deposited in all the above mentioned basins. The organic-rich sequences are characterized by thin lamination, absence of bioturbation, rare benthonic fauna (if present, it is supplied from other parts of the basin) and excellent preservation of >exotic> fossils (plant leaves, insects, amphibians). The suitable depth conditions needed for permanent stratification in the water bodies and anoxia in the deeper parts of the lakes, were due essentially to increasing subsidence outstripping deposition. Intense tectonic activity is recorded by the occurrence of olisthostromes and slumps affecting the lacustrine deposits as well as by the syntectonic structures recorded in the basin-fill successions. The late Oligocene-late Miocene paleoclimatic regimes, ranging from warm tropical to subtropical conditions, were favourable for the development of permanently stratified lakes. Moreover chemical ectogenic meromixis may have contributed in some cases to the establishment of permanent stratification. The Eastern Iberian rift system, makes up the southernmost part of the larger Western European rift system. The occurrence of lacustrine sediments ranging from the late Eocene to late Miocene, is frequent in the fault-bounded basins of this complex rift system and lacustrine oil-shale deposits have been recorded in several of these basins. Thus the Western European rift system presents an interesting model of intracontinental rifting in a foreland platform setting, where favourable conditions for organic rich deposits often took place. The high potential of this kind of tectonic settings for lacustrine oil-shale exploration must be stressed. © 1989.

Peer Reviewed