Raman spectroscopic screening of cyanobacterial chasmoliths from crystalline gypsum - The Messinian crisis sediments from Southern Sicily
Abstract
This study shows the first results on Raman spectroscopic investigations of pigments from cyanobacterial endolithic colonisations in gypsum of Messinian age (Miocene). Gypsum from outcrops of sedimentary series close to Eraclea Minoa (Sothern Sicily) is sometimes inhabited by endoliths.
Raman spectroscopic investigations allow to specify type of colonisation through identification of their pigments. Coccoid cyanobacteria (Chroococcidiopsis sp., Gloeocapsopsis pleurocapsoides, Gloeocapsa compacta, and Synechococcus sciophilus), filamentous heterocytous Nostoc sp., and filamentous bundle-forming Symplocastrum cf. aurantiacum and Microcoleus sp. were found to inhabit different parts of the gypsum samples.
Carotenoids (as assumed frequently beta-carotene) are produced in all the samples studied (optimised detection using 514-nm excitation), scytonemin in the samples colonised by G. pleurocapsoides (G1, G2, and G6), and phycobiliproteins in the sample G3 (those detected using 785-nm excitation). This study is the first initiative to collect better knowledge on detecting biomarker traces in the frame of Messinian-age gypsum sequence of relevance for old Martian environments.