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Magnetite‐Fluorite Rock: A New Rock Type of Hot Water Sedimentation
Author(s) -
Shaokang XU,
Xuehui XIA,
Congjian YUAN,
Bingquan WANG,
Fei YAN,
Shengxian YAN,
Xingquan ZHENG
Publication year - 2008
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/j.1755-6724.2008.tb00645.x
Subject(s) - geology , fluorite , geochemistry , magnetite , diagenesis , sedimentary rock , mineralogy , chlorite , chemical composition , hydrothermal circulation , quartz , metallurgy , paleontology , materials science , physics , thermodynamics , seismology
The new type hot water sedimentary rock — magnetite‐fluorite rock occurs as quasi‐layers in flat parts of contact zones between rock body and strata in Bamianshan of Changshan County, Zhejiang Province, China. The main mineral assemblage is fluorite+magnetite+cassiterite. The rock shows typical laminated structure and obvious mosaic texture. Its formation temperature is between 123°C‐160°C, averaging at 142°C. The major chemical composition of the rock includes CaF 2 , SiO 2 , Al 2 O 3 , FeO, and Fe 2 O 3 ; the high‐content microelement association includes W, Sn, Be, Rb, Sr, S, and CI; and the total content of REE is low (ΣREE between 35.34times10 −6 ‐38.35times10 −4 ), showing LREE enrichment type of distribution pattern. Diagenesis: driven by the tectonic stress, the formation water heated in the deep strata had moved along the fissures or fractures in strata and had extracted components from the strata on the way, and finally stagnated in the flat parts of contact zones between rock body and strata. With drop in temperature, magnetite and fluorite were separated from the hot water and precipitated alternately, forming this hot water sedimentary rock with new type mineralogical composition, typical laminated structure, obvious mosaic texture and sub‐horizontal occurrence. The characteristics of the new type mineralogical composition, sedimentary tectonic environment and chemical composition are different from that of the well‐known traditional hydrothermal sedimentary rocks.