Anonymous
Anonymous asked in Science & MathematicsEarth Sciences & Geology · 10 years ago

LILs and HFS elements in hydrothermal processes?

What is the behavior of LILs and HFS elements in hydrothermal processes that can have an effect on rock chemistry?

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  • 10 years ago
    Best Answer

    LIL = Large ion lithophile (K, Rb, Ba, Th) , HFS = High field strength (Nb, Ta, Zr, Hf, Ti)

    Both LIL & HFS elements have a recognised influence on certain igneous rock chemistries through hydrothermal injection & metasomatism. These elements are almost uniquely found in felsic rocks & specifically in granites.

    LIL elements are rejected or exceptionally diluted in mafic igneous rocks which leads to them associating with felsic (granitic) fractionated material especially late pegmatites.

    There are many granitic intrusions specifically in Africa which have a very strong HFS signature. I have often wondered why granites with this particular geochemical signature are limited to Africa.

    In its abstract, the link below states 'The LIL elements such as Rb, Sr & Ba behaved differently, which may be attributed to the different fates of their main hosting minerals. The ore-forming elements such as Cu, Pb, Zn, Ag & Sn were remarkably added to the altered phylites, while Hf, Th, U, Nb & Zr remainder rather constantly during hydrothermal alteration. It is suggested by the REE features that ore-forming fluids probably found their ways upwards from ther depth through faults to the locus of ore deposition. The degree of REE mobility increases with the sizes of the orebodies. Thus, REE is probably an effective geochemical indicator for distiguishing between small & large orebodies at the later stage of exploration.'

  • 4 years ago

    Nuclear fusion processes in stars, heavier elements by supernovae.

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