Carbonaceous materials (CMs) have been widely used to assess temperatures in sedimentary and metamorphic carbonate rocks. The use of Raman spectroscopy of carbonaceous material (RSCM) is largely devoted to the study of deformed rocks hosted in thrust-tectonic settings. Raman spectroscopy of carbonaceous material successfully allows the study of carbonate rocks at a temperature as high as 650 °C. In this study, a set of carbonate-mylonite rocks (Italian Alps) were investigated using micro-Raman spectroscopy, in order to infer the deformation conditions associated with the Alpine thrusts, expected to occur at T < 350 °C. Micro-Raman spectra were collected using two sources: green (532 nm) and red (632.8 nm) lasers. Several deconvolution procedures and parameters were tested to optimize the collected spectrum morphologies for the laser sources, also in accordance with the low temperature expected. The obtained temperatures highlight two clusters: one at 340–350 °C for the samples collected in the axial part of the Alpine chain, and the other at 200–240 °C for those collected in the external thrust-and-fold belt. These results agree with the independent geological and petrological constraints. Consistent results were obtained using 532 and 632.8 nm laser sources when the appropriate deconvolution approach was used.

Evaluation of Deformation Temperatures in Carbonate Mylonites at Low Temperature Thrust-Tectonic Settings via Micro-Raman Spectroscopy / A. Croce, E. Pigazzi, P. Fumagalli, C. Rinaudo, M. Zucali. - In: MINERALS. - ISSN 2075-163X. - 10:12(2020 Nov 29). [10.3390/min10121068]

Evaluation of Deformation Temperatures in Carbonate Mylonites at Low Temperature Thrust-Tectonic Settings via Micro-Raman Spectroscopy

E. Pigazzi
Secondo
;
P. Fumagalli;M. Zucali
Ultimo
2020

Abstract

Carbonaceous materials (CMs) have been widely used to assess temperatures in sedimentary and metamorphic carbonate rocks. The use of Raman spectroscopy of carbonaceous material (RSCM) is largely devoted to the study of deformed rocks hosted in thrust-tectonic settings. Raman spectroscopy of carbonaceous material successfully allows the study of carbonate rocks at a temperature as high as 650 °C. In this study, a set of carbonate-mylonite rocks (Italian Alps) were investigated using micro-Raman spectroscopy, in order to infer the deformation conditions associated with the Alpine thrusts, expected to occur at T < 350 °C. Micro-Raman spectra were collected using two sources: green (532 nm) and red (632.8 nm) lasers. Several deconvolution procedures and parameters were tested to optimize the collected spectrum morphologies for the laser sources, also in accordance with the low temperature expected. The obtained temperatures highlight two clusters: one at 340–350 °C for the samples collected in the axial part of the Alpine chain, and the other at 200–240 °C for those collected in the external thrust-and-fold belt. These results agree with the independent geological and petrological constraints. Consistent results were obtained using 532 and 632.8 nm laser sources when the appropriate deconvolution approach was used.
carbonaceous materials; Raman spectroscopy; shear zone; fault; thrust;
Settore GEO/03 - Geologia Strutturale
Settore GEO/07 - Petrologia e Petrografia
Settore GEO/06 - Mineralogia
   Dipartimenti di Eccellenza 2018-2022 - Dipartimento di SCIENZE DELLA TERRA "ARDITO DESIO"
   MINISTERO DELL'ISTRUZIONE E DEL MERITO
29-nov-2020
27-nov-2020
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/794252
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