Raman spectroscopy of a microbialite sample in Laguna Pozo Bravo

Raman spectroscopy analysis was performed on a microbialite sample from Laguna Pozo Bravo to assess mineralogical variations through both macro- and microscopic observations. Spectra were acquired using backscattering geometry with a LabRam HR Evolution Raman microspectrometer, set to a resolution of 0.4 cm⁻¹ and equipped with a He-Ne laser line (633 nm) at INQUIMAE (UBA-CONICET), Buenos Aires, Argentina. Beam power and acquisition times were optimised for each sample to obtain informative spectra without causing sample alteration. Spectra were recorded using a 50× microscope objective (spatial resolution of approximately 1 μm), with an exposure time of 10-30 s and three accumulations. For band identification, we consulted the RRUFF database (https://rruff.info) and complemented this data with detailed mode assignments from Post, J. <i>et al.</i>