David M. Jenkins
Professor
of Geology
PhD
1980 University of Chicago
Science
I, Room 267
(607) 777-2736
dmjenks@binghamton.edu
Areas
of Research
- Experimental
Petrology
- Stability
of common minerals at crustal and upper-mantle pressures and temperatures
- Equilibrium
chemical reactions between minerals and aqueous solutions
- Non-equilibrium
aspects of mineral formation
- Reaction
mechanisms and rates of mineral growth
- Diffusion
rates of anions and cations
- Extraction
of thermodynamic data derived from experimental mineral equilibria
- Crystal
Chemistry
- Chemical
substitutions in common minerals
- Distribution
of cations within mineral structures
- Changes
in crystal lattice with changes in chemical composition
- Metamorphic
Petrology
- Geothermometry
and geobarometry of metamorphosed mafic rocks
- Fluid
rock interactions at high pressures and temperatures
Links
to Analytical Facilities Available at Binghamton University
JEOL-8900
'Super Probe'
X-ray
diffractometer
Recent
Research Projects by D. Jenkins
- Stability
and crystal-chemistry of ferro-actinolite, in collaboration with Krassimir
Bozhilov (University of California – Riverside)
- Mechanism
of nucleation and growth of tremolitic amphibole from oxides, in collaboration
with Krassimir Bozhilov and David Veblen (Johns Hopkins University)
- Role of
water content on the synthesis of glaucophane
- Low-pressure
stability of glaucophane relative to talc and albite
- Formation
conditions of Na-Mg-rich triple-chain silicates
- Relative
stability of double- and triple-chain silicates
Recently
Completed Research Projects by Graduate Students
- Juan Carlos Corona –
Investigated the reaction of glaucophane and quartz to talc and albite
in the range of 600-750°C and 0.7-2.2 GPa. This reaction serves as a
model for the blueschist-to-greenschist facies transition and is the
geologically relevant boundary for the low-pressure stability of
end-member glaucophane. By defining the location of this boundary we
are better able to define the pressures at which high-pressure
(blueschist-facies) metamorphism occurs in nature.
- Haroldo Lledo
– Obtained compositional half-brackets on the iron content of
actinolitic amphibole equilibrated in the presence of orthopyroxene and
clinopyroxene over the range of 600-890°C and 0.1-0.4 GPa. These
half-brackets provided important limiting experimental data on the
change in the stability of actinolitic amphibole with temperature, for
which there are very few data in the literature. He also investigated
the upper-thermal stability of one particular natural actinolite (Fe# =
0.22) to demonstrate that this phase does indeed have a high thermal
stability (maximum of 860°C at 0.4 GPa). This study has applications
to both the realm of metamorphic rocks, where actinolite is a very
common mineral, and igneous rocks, where actinolite is found in some
Kiruna-type iron-ore deposits. Investigation of the formation of
actinolite coexisting with immiscible iron-rich melts separated from
andesitic magma was done in conjunction with Prof. Naslund.
- Bridget McCollam (Ams) – Synthesized large quantities of the triple-chain silicate Na3.34Mg8.16Si12O30.46(OH)6.74 and of the nearly iso-chemical double-chain silicate Na2.26Mg5.45Si8O21.26(OH)2.64
for the dual purposes of (1) experimentally investigating the phase
equilibrium boundary between these two minerals in pressure-temperature
space, and (2) making calorimetric measurements of their enthalpies of
formation and third-law entropies. This study is the first to provide
definitive calorimetric data for a triple-chain silicate, which, in
turn, provides a valuable basis for determining if this class of
minerals has any stability field or whether they are completely
metastable relative to other minerals. Using the data from this study
it is possible to show that this triple-chain silicate could form from
ultramafic rocks (from chrysotile and talc) in an oceanic environment
but only far from mid-ocean ridges.
Journal
Publications: (Last 5 years)
- Driscall,
J., Jenkins, D.M., Dyar, M.D., and Bozhilov, K.N. (2005) Cation
ordering in synthetic low-calcium actinolite. American Mineralogist,
90, 900-911.
- Senda, K.,
Ishida, K., and Jenkins, D.M. (2005) X-ray Rietveld refinement and FTIR
spectra of synthetic (Si,Ge)-richterites. American Mineralogist, 90,
1062-1071.
- Jenkins, D. M. and
Corona, J. C. (2006) The role of water in the synthesis of
glaucophane. American Mineralogist, 91, 1055-1068.
- Jenkins,
D. M. and Corona, J. C. (2006) Molar volume and thermal expansion of
glaucophane. Physics and Chemistry of Minerals, 33, 356-362.
- Bozhilov,
KN., Brownstein, D., and Jenkins, D.M. (2007) Biopyribole evolution
during tremolite synthesis from dolomite and quartz in CO2-H2O fluid. American Mineralogist, 92, 898-908.
- Corona,
J. C. and Jenkins, D. M. (2007) An experimental investigation of the
reaction: glaucophane + 2 quartz = 2 albite + talc. European Journal
of Mineralogy, 19, 147-158.
- Lledo,
H. L. and Jenkins, D. M. (2008) Experimental investigation of the
upper-thermal stability of Mg-rich actinolite; Implications for Kiruna
type iron deposits. Journal of Petrology, 49, 225-238.
- Ishida,
I., Jenkins, D. M., and Hawthorne, F. C. (2008) Mid-IR bands of
synthetic calcic amphiboles of tremolite-pargasite series and of
natural calcic amphiboles. American Mineralogist, 93, 1112-1118.
- Ams,
B. E., Jenkins, D. M., Boerio-Goates, J., Morcos, R. M., Navrotsky, A.,
and Bozhilov, K. N. (2009) Thermochemistry of a synthetic Na-Mg rich
triple-chain silicate: determination of thermodynamic variables.
American Mineralogist (in press)
Questions or comments:
dmjenks@binghamton.edu
