Las margas radiolaríticas de la Unidad Intermedia del JabalcuzSan Cristóbal. Cordilleras Béticasedad y consideraciones genéticas-paleogeográficas

Resumen

New radiolarian-ages of siliceous deposit occurring in the Middle Jurassic of the Intermediate Unit are presented. Radiolarian dating of sections studied documents a systematic diachronism of the basal onset of radiolarites spanning the Bathonian to Oxfordian. The radiolarian age and the sedimentary features of radiolaritic deposits allow us to well separate two distinct sectors in this unit. The western part shows a more basinal character, at least during the deposition of the lower green member (clastic redeposits, important clayely inputs, bottom current actions etc.), starting the siliceous sedimentation in the late Bathonian. The eastern part of the unit shows a late Callovianearly Oxfordian start of radiolarite sedimentation and a more starved environment. However, the end of the siliceous sedimentation occurs simultaneously throughout the Jabalcuz-San Cristobal unit in the latest Oxfordian, when a drastic change in the sedimentation regime took place and carbonate become the main deposit.