Figure 5 | Scientific Reports

Figure 5

From: Uppermost Triassic phosphorites from Williston Lake, Canada: link to fluctuating euxinic-anoxic conditions in northeastern Panthalassa before the end-Triassic mass extinction

Figure 5

Raman spectroscopic analysis. (a) Representative Raman spectrum of phosphate cortex showing high intensity peaks of D-G bands and deconvolution of D and G bands modeled by six Gaussian peaks below (fitted peaks are scaled for clarity). High intensity peaks of D-G bands and big difference between bands D4 and D verify the biogenic origin of carbonaceous matter34. Sample PC7. (b) The second derivative spectra derived from the first order carbon spectra (A) shows no negative doublet on the negative peak at the G band (see red arrow) corroborating the presence of biogenic carbonaceous material within phosphate cortices. Sample PC7. (c) Representative Raman spectrum of calcareous matrix showing low intensity peaks of D-G bands and deconvolution of D and G bands modeled by three Gaussian peaks below (fitted peaks are scaled for clarity). CC = calcite. Sample PC7. (d) The second derivative spectra derived from the first order carbon spectra (C) shows absence of any intensity within D-G bands corroborating the absence of biogenic carbonaceous material within calcareous matrix. Sample PC7. (e) Representative Raman spectrum of nuclei of PCG showing low intensity peaks of D-G bands. QTZ = quartz. Sample PC7.

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