Hi Everyone!

Interested in hot fluids, thermo, ore deposits and geothermal systems? Just
follow that link, scroll down and click Theme 7L for your Goldschmidt
abstract submission.

https://2021.goldschmidt.info/goldschmidt/2021/cfp.cgi

*Session 7L: Hot fluid frontiers: thermodynamics, molecular dynamics, and
reactive transport in ore deposits and geothermal systems *

Conveners: Alexander Gysi (New Mexico Tech), Nicole Hurtig (New Mexico
Tech) Sandro Jahn (U. Cologne), Thomas Driesner (ETH Zurich)

Provisional Keynote: David Dolejs (U. Freiburg)

Session Description:
Molecular properties, thermodynamics, and the reactive transport of
hydrothermal fluids provide a key link to a quantitative understanding of
heat and mass transfer as well as chemical reactions controlling the
formation of ore deposits and the evolution of active geothermal systems.
New advances in the study of high temperature and pressure fluids using
laboratory experiments, molecular dynamics simulations and large-scale
reactive transport simulations have significantly improved our
understanding of the physical and chemical behavior of these fluids in
natural systems. However, linking these different approaches is challenging
and reveals limitations in our ability to capture the full complexity of
high temperature fluids and to develop sound predictive theoretical models
valid over wide ranges of pressure, temperature and composition. The goal
of this session is to bring together a community interested in
thermodynamic and transport properties of high temperature aqueous fluids.
We invite contributions from experimental studies, molecular dynamics,
thermodynamic model development, reaction modeling, and large-scale
reactive transport simulations revolving around tackling the frontiers in
physical and chemical properties of hydrothermal fluids with applications
to and examples from natural ore deposits and geothermal systems.

--

Dr. Alexander Gysi
Economic Geologist
New Mexico Bureau of Geology & Mineral Resources
New Mexico Tech
801 Leroy Place
Socorro, NM 87801

Assistant Professor,
Department of Earth & Environmental Sciences
New Mexico Tech

Email: alexander.gysi@nmt.edu
Phone: 575-835-5754

Dear American Mineralogist Readers,

Below are the Paper Highlights for the February 2021 issue of the American Mineralogist: International Journal of Earth and Planetary Materials. You may also view the American Mineralogist Paper Highlights list at here (http://www.minsocam.org/MSA/Ammin/AM_NotableArticles.html).

The DOI links below will take you to the abstract on GeoScienceWorld.

If you have “IP” access via your institution’s library, it should reveal the whole paper. Consult your institution’s IT department or friendly librarian.

If you have MSA membership, then authenticate in from the American Mineralogist menu (herehttp://www.msapubs.org/ directly). Once at the portal page, click the right-side American Mineralogist link, enter your user name (e-mail address), and your password (membership number). Then search via your browser’s search tools for the paper you want to read. (On Rachel’s computer, it is control-f but we think that is little different for everyone.)

Note that on GSW you can sign up for a table of contents to be sent you when the issue is live -- this is a feature open to anyone who registers on the site.

Thank you for reading American Mineralogist.

Sincerely,
Hongwu Xu

Don Baker

Effect of water on carbonate-silicate liquid immiscibility in the system KAlSi3O8-CaMgSi2O6-NaAlSi2O6-CaMg(CO3)2 at 6 GPa: Implications for diamond-forming melts
https://doi.org/10.2138/am-2020-7551
Partial melting of recycled sediments (metapelites) subducted to mantle depths is essentially controlled by the phengite/K-feldspar + clinopyroxene + carbonate assemblage. Here Shatskiy et al. show that at 6 GPa and nominally dry conditions incipient melting of this assembly occurs at 1050-1100 °C and yields a K-dolomitic melt. By contrast, in the presence of H2O two immiscible phonolite-like and K-dolomitic melts appear. The established melts resemble the carbonatitic and silicic HDFs established in diamonds worldwide.

Jasonsmithite, a new phosphate mineral with a complex microporous framework, from the Foote mine, North Carolina, U.S.A.
https://doi.org/10.2138/am-2020-7582
Kampf et al. describe a new mineral, jasonsmithite, from the Foote mine in North Carolina. It has a complex framework structure containing large channels. Its 70% void space makes it one of the most porous mineral structures known and suggests that it may have technological applications.

Titanium in calcium amphibole: Behavior and thermometry
https://doi.org/10.2138/am-2020-7409
Thermometry of high-grade metamorphic rocks is difficult due to fast cationic diffusion during slow cooling. Liao et al. propose to use Ti content of amphibole (Ti-Amp) as thermometric tools for igneous and high-grade metamorphic rocks.

Phase relationships in the system ZnS-CuInS2: Insights from a nanoscale study of indium-bearing sphalerite
https://doi.org/10.2138/am-2020-7488
Xu et al. conducted micrometer- to nano-scale characterization on sphalerite containing 17-49 mol% CuInS2 that occurs in a pyrrhotite-dominant matrix. Results provide new insights into phase relationships in the system ZnS-CuInS2. Metal ordering is modeled as mixed sites in a sphalerite-type structure, [(Cu,In,Zn)3(Zn0.5Fe0.5)]4S4, with P4-3m symmetry. This modification is distinct from the reported cubic-tetragonal phase transition. Different degrees of fluid percolation explain the textures shown.

Major and trace element composition of olivine from magnesian skarns and silicate marbles
https://doi.org/10.2138/am-2020-7566
Nekrylov et al. analyzed olivine from magnesian skarns and silicate marbles, which could be easily distinguished from olivine formed in other processes by unusually low contents of Ni, Co, and Cr and high content of B. These features are linked to the composition of its formation environment -- dolomites and their contacts with intermediate-acidic magmatic rocks.

Decompression experiments for sulfur-bearing hydrous rhyolite magma: Redox evolution during magma decompression
https://doi.org/10.2138/am-2020-7535
Understanding redox evolution during magma ascent is important for exploring oxygen fugacity of magma and mantle and for modeling and predicting the chemical species of volcanic gases emitted to the surface. Okumura et al. experimentally investigated redox evolution during magma ascent to the surface. Results showed that sulfur-bearing hydrous rhyolite magma is slightly reduced during the ascent with decompression rates corresponding to explosive and effusive volcanic eruptions.

On the crystal chemistry of sulfur-rich lazurite
https://doi.org/10.2138/am-2020-7317
Sapozhnikov et al. report that dark-blue lazurite from Malo-Bystrinskoe deposit (Russia) contains high sulfur. In addition to SO42-, the S3- radical-ion occupies beta-cages within the structure. The idealized formula of the mineral is Na7CaAl6Si6O242–(S3)–·H2O. The structure of studied lazurite contains incommensurate modulations.

Experimental evaluation of a new H2O-independent thermometer based on olivine-melt Ni partitioning at crustal pressure
https://doi.org/10.2138/am-2020-7014
Pu et al. demonstrate that the partitioning of Ni between olivine and basaltic melt (DNi) is independent of dissolved water (up to 4.3 wt%), unlike the partitioning of Mg (DMg). Olivine-melt equilibrium experiments were performed at 1 bar (anhydrous) and 0.5 GPa (anhydrous and hydrous). The results confirm that an olivine-melt thermometer based on DNi can be applied to hydrous natural basalts from subduction zones without any correction for H2O content.

Contrasting compositions between phenocrystic and xenocrystic olivines in the Cenozoic basalts from central Mongolia: Constraints on source lithology and regional uplift
https://doi.org/10.2138/am-2020-7431
Two Cenozoic prominent features are spatio-temporally associated in central Mongolia, i.e., the continental basalts and regional uplift, but their causes and relationship remain unclear. To solve these issues, Zhang et al. conducted analyses of major and trace element compositions for olivine phenocrysts and xenocrysts in the Cenozoic basalts. They conclude that mass deficit in the lithosphere could have caused isostatic uplift of central Mongolia in the Cenozoic.

The composition of garnet in granite and pegmatite from the Gangdese orogen in southeastern Tibet: constraints on pegmatite petrogenesis
https://doi.org/10.2138/am-2020-7388
Yu et al. report two stages of garnet growth in granite and pegmatite from the Gandese orogen in Tibet. The first generation of garnet (Grt-I) grew in the pegmatite from early evolved magmatic-hydrothermal fluids, and the second generation (Grt-II) crystallized after dissolution of the preexisting pegmatite garnet in the presence of a granitic magma. Both granite and pegmatite originate from partial melting of the same juvenile crust in the Mesozoic continental arc prior to the Cenozoic continental collision forming the Himalayan orogen.

Formation of metasomatic tourmalinites in reduced schists during the Black Hills Orogeny, South Dakota
https://doi.org/10.2138/am-2020-7405
Boron is an important component of granites, pegmatites, and metamorphic rocks in many geologic settings, including collisional orogens. Boron is a highly fluid-mobile element and thus it exchanges easily between these geologic materials. Nabelek describes mineral chemistry of tourmalinite in the Black Hills orogen and proposes ion-exchange reactions that led to its formation. The tourmalinite places constraints on the chemistry of the fluid that caused replacement of a schist by tourmaline and graphite.

New insights into the crystal chemistry of sauconite (Zn-smectite) from the Skorpion zinc deposit (Namibia) via a multi-methodological approach
https://doi.org/10.2138/am-2020-7460
Schingaro et al. conducted a multi-methodical characterization of a sauconite (Zn-bearing trioctahedral smectite) specimen from the Skorpion ore deposit (Namibia) using X-ray diffraction, cation exchange capacity analysis, differential thermal analysis, thermogravimetry, infrared spectroscopy and transmission electron microscopy. The results have implications not only for economic geology/recovery of critical metals but also, more generally, in the field of environmental sciences.

The new mineral crowningshieldite: A high-temperature NiS polymorph found in a type IIa diamond from the Letseng mine, Lesotho
https://doi.org/10.2138/am-2020-7567
Smith et al. describes crowningshieldite, a new nickel monosulfide mineral that is the high-temperature polymorph of millerite. It was discovered within a fine-grained multi-phase inclusion in a gem quality diamond from the Letseng Mine, Lesotho. The mineral name recognizes G.R. Crowningshield, who was a central figure in research at the Gemological Institute of America for over fifty years.

Elucidating the natural-synthetic mismatch of Pb2+Te4+O3: The redefinition of fairbankite
https://doi.org/10.2138/am-2020-7536
The determination of fairbankite's structure by Missen et al. has solved the long-standing uncertainty around the natural Pb2+Te4+O3 formula. Additionally, the fairbankite structure is unique and contains a trimeric tellurite anion new to both synthetic and natural structures.

Are the Thermodynamic Properties of Natural and Synthetic Mg2SiO4-Fe2SiO4 Olivines the Same?
https://doi.org/10.2138/am-2021-7764CCBY
It is unclear whether the thermodynamic properties of some rock-forming minerals and their synthetic analogues are quantitatively the same. Olivine is an important substitutional solid-solution consisting of the two end-members forsterite, Mg2SiO4, and fayalite, Fe2SiO4. Gieger et al. undertook first low-temperature CP measurements on two natural olivines between 2 and 300 K; nearly end-member fayalite and a forsterite-rich crystal Fo0.904Fa0.096. They show that the CP behavior of the natural and synthetic crystals is similar.

Dear colleagues,

I would like to advertise Ph.D. position, funded by the German research
foundation, on solute thermodynamics in high-temperature fluids relevant
to magmatic devolatization and hydrothermal ore formation:

https://www.minpetro.uni-freiburg.de/downloads/advert.pdf

Please feel free to forward this information to any potential
candidates.  The applications will be reviewed as they come in.

With best wishes,
David

--
David Dolejs  (Professor of Mineralogy & Petrology)
Institute of Earth and Environmental Sciences, University of Freiburg
Albertstr. 23b, 79104 Freiburg i.Br., Germany
Tel direct: +49 (0)761 203 6395 / secretary: +49 (0)761 203 6396
Fax: +49 (0)761 203 6407
Web: http://www.minpetro.uni-freiburg.de/team/dolejs