Eliminación de fosfatos en muestras palinológicas.

Abstract

The observation of palynological material from siliceous sediments needs separation andisolation techniques, which include a preliminary chemical treatment to eliminate mineral phases. Thefinal residue, obtained after several treatments, is composed by a mixture of organic, vegetal and animalmaterials. In some cases the presence of mineral phases such as crystalline phosphates formed duringthe chemical attack is also confirmed. The elimination of these compounds from the palynologicalmaterials is very important for an adequate observation, study and count under the optical microscope.The aim of this work is to study and describe the newly formed phosphates during chemical treatmentand to formulate a valid method for its elimination without damage of the playnological material. Twosamples (Keuper facies, Upper Triassic) have been selected due to their content in the previouslydescribed problematic phosphate phases. XRD, XRF and optical microscopy data show that the newlyformed phosphate phases, after the acid attack with HF (40% dissolution), are crandallite-gorceixite.After several laboratory attempts, the elimination of the problematic phases has been made successfullytreating the samples with a final dissolution of HCl at 33%. All the morphological characteristics of thepalynological material have been preserved properly.