Short course

PROGRAM

of

Short Course

Fluids in the Earth

May 10-14th, 2014

 

Presented by

R. J. Bodnar

Virginia  Tech, Blacksburg, VA, U.S.A.

L. V. Danyushevsky

Tasmania University, Hobart, Australia

B. De Vivo

University of Napoli Federico II

M. L. Frezzotti

University of Milano Bicocca

J. D. Webster

American  Museum Natural History, N.Y., USA      

 

at

Nanjing University

 

May 10th, 2014

Introduction to the course (Bodnar;  1 hour)

 

The geohydrologic cycle (Bodnar; 1  hour)

The whole Earth system can be  divided into the following reservoirs for H2O: atmosphere, biosphere, oceans,  surface water, groundwater, glaciers and polar ice, continental crust, oceanic  crust, upper mantle, transition zone, lower mantle and core. The amount of H2O contained in each of these  reservoirs will be discussed, as well as the fluxes of H2O between reservoirs and residence  times for H2O in the different reservoirs.

 

Introduction to phase equilibria and  thermodynamics' (All; 2 hours)

The Gibbs Phase Rule; the  Clausius-Clapeyron relationship; activity, fugacity; chemical potential and  equilibrium; the definition of free energy and how it can be estimated from PVT  data; solubility and saturation of volatiles in melts and fluids; melting  diagrams for solid solutions; equilibrium between melts and simple solid  solutions, the effects of changing melt/crystal proportions on the  compositional evolution of solid solutions during crystallization; the effect  of volatiles on crystallization temperatures of primitive magmas as a function  of pressure

 

Introduction to phase equilibria and  thermodynamics (continued) (All; 3 hours)

 

May 11th, 2014

Introduction to fluid  Inclusions and fluid phase equilibria (Bodnar; 4 hours)

Identification, analysis and  application of fluid inclusions to geologic problems.

 

Introduction to micro-Raman  spectroscopy (Frezzotti; 2 hours): Raman spectroscopy is  a non-destructive technique for fluid inclusion analysis, with a wide field of  applications ranging from qualitative detection of solid, liquid and gaseous  components to identification of polyatomic ions in solution. The main  advantages of this technique are the minimal sample preparation and the high  versatility. The procedures to calculate the density of CO2 fluids,  the chemistry of aqueous fluids, and the molar proportions of gaseous mixtures  present as inclusions, will be described.

 

Applications of fluid inclusions in ore-forming environments (Bodnar; 1  hour)

 

May 12th, 2014

Fluid inclusions in UHP metamorphic  rocks (Frezzotti; 1 hour): The chemistry of fluid inclusions in high ultrahigh-pressure  (UHP) metamorphic suites that experienced P–T conditions similar to those occurring  in deep subduction zones (> 80-100 km) provide insight regarding the  geochemical effects of fluid/melt addition to mantle wedges, and to the geochemical  evolution of arc lavas. Examples from the Alps (Italy) and the Dabie-Sulu  (China) UHP rocks will be presented.

 

CO2, carbonate melts, and  brines and in the Earth’s upper-mantle (Frezzotti; 1 hour): Fluid  inclusions in peridotite xenoliths provide a framework for interpreting the  chemistry of fluids in the upper mantle in the different geodynamic settings. In  the lithospheric mantle, the dominant fluid phase is CO2 (± brines),  changing through carbonate melts at rising pressures. Mantle degassing  liberates fluxes of CO2 (± brines), which may eventually reach upper  crustal levels, including the atmosphere. 

 

Introduction to melt inclusions (Danyushevsky; 3 hours)

Melt inclusions are small portions  of melt trapped by crystals growing during magma evolution, and thus can  represent ‘snapshot’ of the conditions that existed during crystallisation. In  this lecture, trapping mechanisms of melt inclusions, their post-entrapment  modifications, and experimental studies of melt inclusions will be discussed.

 

Applications of FI & MI on Vesuvius and Campi Flegrei volcanoes (De  Vivo; 2 hours)

 

May 13th, 2014

Thermodynamics and physics of melt-fluid ± mineral systems (Webster; 4  hours)

Water and carbon dioxide are the  primary magmatic volatile constituents, but sulfur and chlorine are also  important magmatic volatiles. The phase relations of fluid exsolution from  silicate melt, and the influences of these volatiles on magma evolution, fluid  geochemistry, and the generation of mineralizing magmatic-hydrothermal fluids  will be addressed.

 

Thermodynamics and physics of melt-fluid ± mineral systems, continued  (Webster; 3 hours)

Volatile components in silicate  melts influence melting temperatures and melt viscosity. Volatile components  also influence the stability of minerals and fluids and consequently control  larger processes including magma rheology and explosivity. The role of H2O  and CO2 in these processes will be discussed.

 

May 14th, 2014

Using melt inclusions to constrain the origin of phenocrysts in  strongly-phyric volcanic rocks (Danyushevsky; 1 hour)

An important implication of melt  inclusions is to assess whether crystals in volcanic rocks crystallised from  the same magma type as represented by the transporting melt (i.e., the  groundmass of the rock), or are xenocrysts. Different examples from subduction-related  volcanic suites will be shown.

 

Timing crystallisation processes using melt inclusions; Using melt inclusions  to determine komatiite melt compositions; Melt inclusion studies on Vesuvius  (Danyushevsky; 2 hours)

Post-entrapment re-equilibration of  melt inclusions with their hosts can be used to assess crystallisation rates of  individual phenocrysts. Melt inclusions can be a powerful tool for recovering  melt compositions in ancient volcanic suites, when the groundmass in the lavas  is chemically modified by alteration. A summary of melt inclusion studies of  Vesuvius will be presented.

 

Melt inclusions in intermediate to felsic magmas (Webster; 2 hours)

The use  and misuse of geochemical data from silicate melt inclusions of felsic  continental and subduction-zone magmas will be described. Interpreting magma  behaviour with melt inclusion compositions and experimentally determined  volatile solubilities.


Exam on material covered in the short course (2  hours)