E3S Web Conf.
Volume 98, 201916th International Symposium on Water-Rock Interaction (WRI-16) and 13th International Symposium on Applied Isotope Geochemistry (1st IAGC International Conference)
|Number of page(s)||5|
|Section||Geochemical Cycles of Elements and Global Environmental Changes|
|Published online||07 June 2019|
Paleoenvironmental considerations based on geochemistry and mineralogy of a Miocene lacustrine calcrete, southern Portugal
Centro de Ciências e Tecnologias Nucleares (C2TN), Instituto Superior Técnico, Universidade de Lisboa, E.N. 10 (km 139.7), 2695-066 Bobadela LRS, Portugal
2 Departamento de Geociências, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
3 GeoBioTec, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
4 Departamento de Ciencias de la Tierra, Universidad de Huelva, Avda. Tres de Marzo, s/n, 21007, Huelva, Spain.
* Corresponding author: firstname.lastname@example.org
A lacustrine carbonate facies has been investigated in Middle Miocene successions of the western side of the Moura-Marmelar basin, Southern Portugal in order to evaluate paleoenvironments in which carbonates formed, by using geochemistry and mineralogy. The studied formation corresponds to a recent unearthed section of a calcrete with an homogeneous carbonate facies comprising fine, whitish, and powdery material, and the only detected difference is a slightly hardness decrease towards the top, as well as an increase of weathered rock fragments (schist). The calcrete is calcium rich, even some magnesium enrichment was observed at the middle level, which is differentiated by a general depletion of all chemical elements, particularly REE, in both the bulk and clay-size fraction. Regarding the mineralogy, calcite prevails, and dolomite is only present in the middle level of the calcrete, together with a smectite enrichment, suggesting changes to more alkaline and low drainage, lacustrine and arid to semi-arid conditions.
© The Authors, published by EDP Sciences, 2019
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