RT Journal Article
T1 Calcitization of Mg±Ca carbonate and Ca sulphate deposits in acontinental Tertiary basin (Calatayud Basin, NE Spain)
A1 Sanz Rubio, Enrique
A1 Sánchez Moral, Sergio
A1 Cañaveras, Juan Carlos
A1 Calvo Sorando, José Pedro
A1 Rouchy, J.M.
AB Diagenetic carbonates formed through early calcitization of evaporite (gypsum, anhydrite) and/or magnesium carbonate (dolomite, magnesite) deposits have been identified throughout the Tertiary Calatayud Basin (NE Spain). The diagenetic carbonates consist in all cases of low magnesian calcite and are related to main sedimentary discontinuities, which record episodes of significant subaerial exposure in the basin. Early calcite replacements predominate in sediments of the Intermediate Unit in central areas of the basin. Two types of diagenetic carbonates have been distinguished: (1) laminated diagenetic carbonates in which the original structure of sequences formed of laminated magnesite, dolomite and primary gypsum is preserved, though transformed in calcite; (2) brecciated diagenetic carbonates, which resulted from extensive dissolution of lenticular gypsum macrocrystals accompanied by dedolomitization processes of dolomite host rock. The replacement by calcite resulted from rapid transformation of evaporite deposits either at the contact of these deposits with overlying freshwaters or by percolating freshwater at very shallow burial depth. Stable isotope (carbon and oxygen) analyses of the diagenetic carbonates support influence of meteoric-derived carbonate-rich groundwater for their formation. The meteoric isotope signature is supported by its comparison with the stable isotope values determined from diagenetic calcites formed after magnesite in evaporite sequences during the Late Pleistocene and Holocene. The diagenetic carbonate bodies formed as a result of a progressive change from highly to moderately concentrated saline lake waters. This gradual evolution was related to a climatic shift from dry and hot to cooler and more humid conditions throughout the Miocene, a trend that has been also recognized in other large Tertiary basins of the Iberian Peninsula in this period.
PB Elsevier
SN 0037-0738
YR 2001
FD 2001
LK https://hdl.handle.net/20.500.14352/60442
UL https://hdl.handle.net/20.500.14352/60442
LA eng
DS Docta Complutense
RD 29 abr 2024