TY - JOUR

T1 - Formation of spessartine and co2 via rhodochrosite decarbonation along a hot subduction p-t path

AU - Bataleva, Yuliya V.

AU - Kruk, Aleksei N.

AU - Novoselov, Ivan D.

AU - Palyanov, Yuri N.

PY - 2020/8/1

Y1 - 2020/8/1

N2 - Experimental simulation of rhodochrosite-involving decarbonation reactions resulting in the formation of spessartine and CO2-fluid was performed in a wide range of pressures (P) and temperatures (T) corresponding to a hot subduction P-T path. Experiments were carried out using a multi-anvil high-pressure apparatus of a “split-sphere” type (BARS) in an MnCO3–SiO2–Al2O3 system (3.0–7.5 GPa, 850–1250 °C and 40–100 h.) with a specially designed high-pressure hematite buffered cell. It was experimentally demonstrated that decarbonation in the MnCO3–SiO2–Al2O3 system occurred at 870 ± 20 °С (3.0 GPa), 1070 ± 20 °С (6.3 GPa), and 1170 ± 20 °С (7.5 GPa). Main Raman spectroscopic modes of the synthesized spessartine were 349–350 (R), 552(υ2), and 906–907 (υ1) cm−1. As evidenced by mass spectrometry (IRMS) analysis, the fluid composition corresponded to pure CO2. It has been experimentally shown that rhodochrosite consumption to form spessartine + CO2 can occur at conditions close to those of a hot subduction P-T path but are 300–350 °C lower than pyrope + CO2 formation parameters at constant pressures. We suppose that the presence of rhodocrosite in the subducting slab, even as solid solution with Mg,Ca-carbonates, would result in a decrease of the decarbonation temperatures. Rhodochrosite decarbonation is an important reaction to explain the relationship between Mn-rich garnets and diamonds with subduction/crustal isotopic signature.

AB - Experimental simulation of rhodochrosite-involving decarbonation reactions resulting in the formation of spessartine and CO2-fluid was performed in a wide range of pressures (P) and temperatures (T) corresponding to a hot subduction P-T path. Experiments were carried out using a multi-anvil high-pressure apparatus of a “split-sphere” type (BARS) in an MnCO3–SiO2–Al2O3 system (3.0–7.5 GPa, 850–1250 °C and 40–100 h.) with a specially designed high-pressure hematite buffered cell. It was experimentally demonstrated that decarbonation in the MnCO3–SiO2–Al2O3 system occurred at 870 ± 20 °С (3.0 GPa), 1070 ± 20 °С (6.3 GPa), and 1170 ± 20 °С (7.5 GPa). Main Raman spectroscopic modes of the synthesized spessartine were 349–350 (R), 552(υ2), and 906–907 (υ1) cm−1. As evidenced by mass spectrometry (IRMS) analysis, the fluid composition corresponded to pure CO2. It has been experimentally shown that rhodochrosite consumption to form spessartine + CO2 can occur at conditions close to those of a hot subduction P-T path but are 300–350 °C lower than pyrope + CO2 formation parameters at constant pressures. We suppose that the presence of rhodocrosite in the subducting slab, even as solid solution with Mg,Ca-carbonates, would result in a decrease of the decarbonation temperatures. Rhodochrosite decarbonation is an important reaction to explain the relationship between Mn-rich garnets and diamonds with subduction/crustal isotopic signature.

KW - CO fluid

KW - Decarbonation

KW - High-pressure experiment

KW - Manganese

KW - Mantle

KW - Rhodochrosite

KW - Spessartine

KW - Subduction

KW - high-pressure experiment

KW - DIAMOND

KW - STABILITY

KW - CO2

KW - decarbonation

KW - manganese

KW - spessartine

KW - CARBONATION

KW - mantle

KW - KIMBERLITE PIPE

KW - HIGH-PRESSURE

KW - MNCO3

KW - rhodochrosite

KW - TRANSITION

KW - subduction

KW - MINERAL INCLUSIONS

KW - FINSCH

KW - CO(2)fluid

UR - http://www.scopus.com/inward/record.url?scp=85090662351&partnerID=8YFLogxK

U2 - 10.3390/min10080703

DO - 10.3390/min10080703

M3 - Article

AN - SCOPUS:85090662351

VL - 10

SP - 1

EP - 12

JO - Minerals

JF - Minerals

SN - 2075-163X

IS - 8

M1 - 703

ER -