Biotite as a recorder of an exsolved Li-rich volatile phase in upper crustal silicic magma reservoirs
The result's identifiers
Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00025798%3A_____%2F22%3A00000031" target="_blank" >RIV/00025798:_____/22:00000031 - isvavai.cz</a>
Result on the web
<a href="https://pubs.geoscienceworld.org/gsa/geology/article/50/4/481/611422/Biotite-as-a-recorder-of-an-exsolved-Li-rich" target="_blank" >https://pubs.geoscienceworld.org/gsa/geology/article/50/4/481/611422/Biotite-as-a-recorder-of-an-exsolved-Li-rich</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1130/G49484.1" target="_blank" >10.1130/G49484.1</a>
Alternative languages
Result language
angličtina
Original language name
Biotite as a recorder of an exsolved Li-rich volatile phase in upper crustal silicic magma reservoirs
Original language description
The magmatic-hydrothermal transition is key in controlling the fate of many economically important elements due to the change in partitioning when melt and magmatic fluid co-exist. Despite its increasing economic importance, the behaviour of lithium (Li) in such environments remains poorly known. Here we illustrate how compositionally unusual biotites from the rhyolitic Bishop and Kos Plateau tuffs may contain a magmatic volatile phase trapped between layers of biotite crystals. Despite originating in pristine deposits, and showing the expected XRD spectra, these biotites return low (< 95 wt.percent) analytical totals via electron microprobe (EMP) consistent with the presence of considerable amounts of light elements (non-measurable by EMP). Lithium contents and isotope ratios in these biotites are remarkable with abundances reaching >2,300 ppm and exceptionally light Li isotopic compositions (delta7Li as low as -27.6per mille) and large isotopic fractionation between biotite and corresponding bulk samples (D7Libt–bulk as low as -36.5per mille). Other mineral phases, groundmass glass, and melt inclusions from the same units do not support an extremely Li-rich melt prior to eruption. Biotites from phonolitic systems (Tenerife and Campi Flegrei) do not show such extreme compositional differences with biotite and melt showing roughly equivalent Li contents, underscored by significantly reduced D7Libt–bulk to a maximum of -10.9per mille. We ascribe the difference in behavior to the near liquidus appearance of biotite in alkaline magmatic suites, before widespread exsolution of a magmatic volatile phase in the magma reservoir, while in rhyolitic suites, biotite crystallises at low temperature, trapping the co-existing exsolved fluid phase in the reservoir.
Czech name
—
Czech description
—
Classification
Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
—
OECD FORD branch
10505 - Geology
Result continuities
Project
—
Continuities
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace
Others
Publication year
2022
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Geology
ISSN
0091-7613
e-ISSN
—
Volume of the periodical
50
Issue of the periodical within the volume
4
Country of publishing house
US - UNITED STATES
Number of pages
5
Pages from-to
481-485
UT code for WoS article
000752199400001
EID of the result in the Scopus database
2-s2.0-85127926016