%0 Journal Article
%A González Acebrón, Laura
%A Arribas Mocoroa, José
%A Mas Mayoral, José Ramón
%T Role of sandstone provenance in the diagenetic albitization of feldsparsA case study of the Jurassic Tera Group sandstones (Cameros Basin, NE Spain)
%D 2011
%@ 0037-0738
%U https://hdl.handle.net/20.500.14352/41943
%X The Cameros Basin (Iberian Chain, NE Spain) formed during the latest Jurassic–Early Cretaceous rifting stage in anextensional regime characterized by high subsidence rates. Its sedimentary infill (thicker than 6000 m) has beensubdivided into eight depositional sequences (DS) mainly composed of continental sediments. DS 1 and DS 2represent the first rifting stage (Tera Group, Tithonian), mainly formed by fluvial and lacustrine sediments.Sandstone petrofacies evolved from quartz-sedimentolithic in DS 1 to quartz-feldspathic in DS 2 due to the riftingprocess. In DS 2, three different types of detrital feldspars (K-feldspars, albites and polysynthetic plagioclases) withsimilar sodium-rich compositions (mean: Ab94.0 An4.5 Or1.5) can be recognized. Chemically pure nonluminescentalbites (AbN99%) are common. In DS 2, diagenetic albitization of both plagioclases and K-feldspars is inferred fromconventional microscopy observations, cathodoluminescence and electron microprobe analyses. DS 1 contains fewplagioclase grains, which showno evidence of transformation into albite.Although the albitization is characterized asdiagenetic it seems to be provenance-controlled since it affects the units showing higher original plagioclase/Kfeldsparratio (DS 2), due to the greater influence of plutonic and metamorphic source areas in DS 2. Possible Nasources are: (1) the percolation ofmoderate to high salinity residual brines fromrelated alkaline lakes developed attop of DS 2 in the eastern sector of the basin, (2) clay mineral reactions (sodium smectite to illite and chlorite)indicated by mudstone composition in the interlayered mudstones, and (3) the replacement of detrital sodiumplagioclases by carbonate. These three sources can be complementary.
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