RT Journal Article T1 Geoquímica microestructural en Praeradiolites ciryi (Hippuritacea, Bivalvia, Cretácico Superior de Gredilla de Sedaño, Norte de Burgos, España) T1 Microstructural geochemistry of Praeradiolites ciryi (Hippuritacea, Bivalvia, Upper Cretaceous of Gredilla deSedano, Northern Burgos, Spain) A1 Regidor Higuera, I. A1 García Garmilla, Francisco A1 Zuluaga, María Cruz A1 Elorza, Javier AB The detailed geochemical evolution along two transects of the shell of one specimen of Praeradiolites ciryi is examined along annual, seasonal and fortnightly («doublet») sclerochronological records. The analyzed specimen is thought to have suffered a low diagenetic degree because it mostly retains the original composition of both cellular and compact microstructures of the shell. So it can be deduced from the .«saw-tooth» geochemical profiles, the Mg-Sr high mmol/mol values, the Mn-Fe low mmol/mol values and the unequal distribution of luminescence that accurately follows shell microstructural features. The organic control upon the geochemistry of the shell is still observable because two zones, each one having a characteristic cationic trend, can be distinguished within a «doublet». This fact is reinforced by changes in the luminescence indicating some periodic phenomenon of fortnightly cyclicity. The decrease in cationic content and increase in organic matter content towards the upper half of the «doublets» could be related to metabolic activity changes preparatory for the construction of a new growth line PB Sociedad Geológica de España YR 2003 FD 2003 LK http://hdl.handle.net/10272/9051 UL http://hdl.handle.net/10272/9051 LA spa DS Repositorio Institucional de la Universidad de Huelva RD 30 may 2026