Research output: Contribution to journal › Article › peer-review
FORMATION CONDITIONS OF BURPALA APATITE-FLUORITE ROCKS: THE RESULTS OF FLUORITE-HOSTED FLUID INCLUSION STUDY (NORTHERN BAIKAL REGION). / Isakova, Aleksandra T.; Starikova, Anastasiya E.; Zatolokina, Kseniya I. et al.
In: Geosfernye Issledovaniya, Vol. 2024, No. 3, 2024, p. 52-64.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - FORMATION CONDITIONS OF BURPALA APATITE-FLUORITE ROCKS: THE RESULTS OF FLUORITE-HOSTED FLUID INCLUSION STUDY (NORTHERN BAIKAL REGION)
AU - Isakova, Aleksandra T.
AU - Starikova, Anastasiya E.
AU - Zatolokina, Kseniya I.
AU - Izbrodin, Ivan A.
AU - Doroshkevich, Anna G.
N1 - Source of financing: The fluid inclusion study of apatite-fluorite rocks was funded by the Russian Science Foundation, project 22-17-00078.
PY - 2024
Y1 - 2024
N2 - The article presents the results of a comprehensive study of fluid inclusions in the fluorite of apatite-fluorite rocks of the Burpala massif, as well as a detailed chemical composition of fluorite. According to the phase composition at room temperature, two types of fluid inclusions are trapped in fluorite of apatite-fluorite rocks: primary multiphase fluid inclusions with 4-5 daughter crystals and secondary fluid inclusions with 1 or 2 crystals. Among the daughter phases of primary multiphase fluid inclusions, halite (NaCl), nahcolite (NaHCO3), burbankite ((Na,Ca)3(Sr,Ba,Ce)3(CO3)5), sidorenkite (Na3Mn(PO4)(CO3)), tenardite (Na2SO4), and villiomite (NaF) are found. The composition of primary multiphase fluid inclusions is alkaline sulfate-chloride-fluoride salt with high concentrations of H2O, CO3 –2, and PO4 –3. Secondary fluid inclusions are less concentrated and lower temperature compared to primary ones. At the same time, based on the ice melting temperatures, the salinity of fluid inclusions with 1–2 crystalline phases (12,9–15 wt % NaCl-eq.) is higher than in two-phase fluid inclusions (6,5–7,9 wt % NaCl-eq.), i.e. a general trend to decrease the salt concentrations in the initial fluid preserved in inclusions was observed during fluorite crystallization: from primary multiphase fluid inclusions (concentrated) → secondary fluid inclusions with 1–2 crystalline phases (low-concentrated) → to secondary two-phase fluid inclusions (the most low-concentrated). In addition, the first data of pyrolysis-free gas chromatography-mass spectrometry analysis of volatiles from primary fluid inclusions in fluorite are presented, showing the presence of a significant content (19,6 rel. %) of hydrocarbons in the fluid phase of the salt melt. Thus, apatite-fluorite rocks were formed at temperatures of about 600 °C from an alkaline sulfate-chloride-fluoride salt melt, which also have high concentrations of H2O, CO3–2, and PO4–3. The REE content in fluorites allows us to consider these rocks as the result of crystallization of salt melt, which, apparently, are a product of crystallization differentiation of alkaline melts responsible for the formation of nepheline syenites of the Burpala massif.
AB - The article presents the results of a comprehensive study of fluid inclusions in the fluorite of apatite-fluorite rocks of the Burpala massif, as well as a detailed chemical composition of fluorite. According to the phase composition at room temperature, two types of fluid inclusions are trapped in fluorite of apatite-fluorite rocks: primary multiphase fluid inclusions with 4-5 daughter crystals and secondary fluid inclusions with 1 or 2 crystals. Among the daughter phases of primary multiphase fluid inclusions, halite (NaCl), nahcolite (NaHCO3), burbankite ((Na,Ca)3(Sr,Ba,Ce)3(CO3)5), sidorenkite (Na3Mn(PO4)(CO3)), tenardite (Na2SO4), and villiomite (NaF) are found. The composition of primary multiphase fluid inclusions is alkaline sulfate-chloride-fluoride salt with high concentrations of H2O, CO3 –2, and PO4 –3. Secondary fluid inclusions are less concentrated and lower temperature compared to primary ones. At the same time, based on the ice melting temperatures, the salinity of fluid inclusions with 1–2 crystalline phases (12,9–15 wt % NaCl-eq.) is higher than in two-phase fluid inclusions (6,5–7,9 wt % NaCl-eq.), i.e. a general trend to decrease the salt concentrations in the initial fluid preserved in inclusions was observed during fluorite crystallization: from primary multiphase fluid inclusions (concentrated) → secondary fluid inclusions with 1–2 crystalline phases (low-concentrated) → to secondary two-phase fluid inclusions (the most low-concentrated). In addition, the first data of pyrolysis-free gas chromatography-mass spectrometry analysis of volatiles from primary fluid inclusions in fluorite are presented, showing the presence of a significant content (19,6 rel. %) of hydrocarbons in the fluid phase of the salt melt. Thus, apatite-fluorite rocks were formed at temperatures of about 600 °C from an alkaline sulfate-chloride-fluoride salt melt, which also have high concentrations of H2O, CO3–2, and PO4–3. The REE content in fluorites allows us to consider these rocks as the result of crystallization of salt melt, which, apparently, are a product of crystallization differentiation of alkaline melts responsible for the formation of nepheline syenites of the Burpala massif.
KW - Burpala massif
KW - apatite-fluorite rock
KW - fluorite
KW - multiphase fluid inclusion
UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85209223518&origin=inward&txGid=a562fa9ce79e7fe6814fa126d37fd4f9
UR - https://www.mendeley.com/catalogue/1876d897-0942-35e6-af04-93b78a595171/
U2 - 10.17223/25421379/32/6
DO - 10.17223/25421379/32/6
M3 - Article
VL - 2024
SP - 52
EP - 64
JO - Геосферные исследования
JF - Геосферные исследования
SN - 2542-1379
IS - 3
ER -
ID: 61301428