PEDOGENETIC CALCRETES IN EARLY SYN-RIFT ALLUVIAL SYSTEMS (UPPER JURASSIC, WEST CAMEROS BASIN), NORTHERN SPAIN

摘要

Exceptional pedogenetic calcretes occur in the earliest syn-rift sedimentary record (Tithonian) of the west Cameros Basin. These calcretes show different types of pedogenetic facies (nodular, massive, laminar, and brecciated-pisolithic) and microfabrics: brecciated intraclasts, carbonate nodules, coated clasts and grains, etched quartz grains, rhizocretions, pedotubules and fragmented alveolar-septal structures. In addition, calcrete fragments have been observed in the conglomerate and sandy channelized deposits that form the alluvial systems, indicating the reworking of previous calcrete deposits.