Isotope composition (δ34S, δ18O) of the Middle Triassic-Early Jurassic sulfates in eastern Iberia
Metadatos
Mostrar el registro completo del ítemEditorial
Elsevier
Materia
Evaporite Isotopy Triassic Keuper Muschelkalk Iberia
Fecha
2022-04-01Referencia bibliográfica
F. Ortí, A. Pérez-López, F. Pérez-Valera, C. Benedicto (2022). Isotope composition (δ34S, δ18O) of the Middle Triassic-Early Jurassic sulfates in eastern Iberia, Sedimentary Geology, 431, 106104. https://doi.org/10.1016/j.sedgeo.2022.106104
Patrocinador
Catalan Government 2017SGR-824; Spanish Government CGL2016-79458-P, PGC2018-098272-B-I00, PID2019-104625RB-I00, PID2020-118999GB-I00; Junta de Andalucía B-RNM-072-GR18, P18-RT-4074, RNM-208Resumen
This study combines published isotope data (223 samples) with new data (153 samples) on the δ34S and δ18O
composition of Ca-sulfate rocks (anhydrite and secondary gypsum) accumulated in eastern Iberia during the
Middle Triassic to Early Jurassic. The δ34S mean values of the evaporite units reveal the following trends: a decrease
from the lower Anisian (~18‰) to the Carnian-Norian interval (~15‰); an increase at the Rhaetian
(~16‰); a decrease in the Hettangian-Sinemurian interval (~14‰); and finally an increasing trend from the
Sinemurian-Pliensbachian (~16‰) to the Pliensbachian-Toarcian (~19‰). This δ34S isotope assemblage together
with the generalized low standard deviations observed for the different evaporite units is consistent, and suggests
that the isotope composition of these Ca-sulfates are primary signatures related to feeding marine water
sulfate. Depending on the evaporite units, these δ34S mean values are, nevertheless, ~1‰ to ~3‰ lower than
those reported for coeval Triassic evaporites of the Germanic basin and the Alp-Apennine domains. In eastern
Iberia, the δ18O values are more variable and also display wider scatters than the corresponding δ34S values. Of
particular interest in our study are: (i) the low δ34S values for the Anisian in comparison with those in the Germanic
basin; (ii) the shift to heavier values in the Rhaetian, recorded for first time in the evaporites of eastern
Iberia; (iii) the low values observed for the Hettangian, which suggest that the change to the heavier values of
the Jurassic (~19‰) occurred after the end-Hettangian in eastern Iberia; and (iv) the affinity of the δ34S values
recorded for the Hettangian-Sinemurian interval to those known for the Canadian domain.