Phosphate, silicate, and oxide minerals as monitors of geodynamic processes
Experiments involving phosphate and silicate minerals cover a wide range of minerals and fluid compositions. Most of these experiments have their origins and inspiration from natural processes involving metasomatically-induced partial alteration and/or re-equilibration of various phosphate and silicate minerals or phosphate-silicate mineral groups.
Experimental projects include:
Experimental metasomatic trace element (Ti and V) alteration of magnetite at 400 to 800 °C and 100 MPa
Experimental fluid-aided incorporation of actinides into monazite and xenotime utilizing both alkali-rich fluids and simple, fluid-rich granitic melts.
Synthesis, crystal chemistry, and thermochemistry of apatite along the F-Cl, F-OH, and Cl-OH joins.
Experimental dissolution of monazite and xenotime in NaCl- and NaF-bearing fluids as a function of P-T-X
Test dating of experimentally fluid-altered, Pb-depleted monazite utilizing electron microprobe analysis.
Experimental incorporation or depletion of Th, U, and (Y+HREE) into zircon utilizing alkali-bearing and Ca-bearing fluids.
Experimental determination of fluorapatite, monazite, xenotime, allanite, and REE-enriched epidote stability fields in monazite-apatite-allanite and xenotime-apatite-allanite metapelitic systems as a function of P-T-X.
LREE-redistribution between fluorapatite, monazite, and allanite at high pressures and temperatures.
Thermodynamic, XRD, IR, Raman, and electron microscopic analytical characterization of apatite across the F – Cl, F – OH, and Cl – OH joins.
Experimental fluid-aided incorporation of (Y+HREE) into garnet as a function of P-T-X.
Experimental metasomatic alteration of low grade banded iron formations under low grade condtions
Experimental replication of high-grade altered banded iron formations
Experimental fluid-aided incorporation of As and Sb into dumortierite under subduction zone P-T conditions.
The experimental stability of scapolite as a function of P-T-XNaCl under amphibolite- to granulite-facies conditions.
High-grade fluid metasomatism in the lower crust and upper mantle
The chemical and physical evolution and stability of the mid to lower crust and upper mantle can be strongly affected by fluids such as H2O, CO2, and KCl/NaCl/CaCl2 brines.
Studies of high-grade fluid metasomatism in the lower crust and upper mantle include:
Changes in the mineral chemistry across traverses of both regional and localised dehydration zones. In these studies, solid-state dehydration by low H2O activity fluids has been and is currently being utilized to demonstrate how hornblende and/or biotite react with quartz to form orthopyroxene +/- clinopyroxene, feldspar and a fluid phase during granulite-facies metamorphism. Low H2O activity fluids include those with a significant CO2 and/or (Na,K)Cl-CaCl2 brine component. Such fluids have been proposed to play a significant role during the granulite-facies metamorphism of basaltic and granitoid rocks in the lower crust.
SIMS analysis of 29 zircon separates across a regional (100 km) traverse of late Archean, lower crust, Shevaroy Block, Tamil Nadu, South India to study how zircon HREE and actinide chemistry, along with U-Th-Pb dating, change during metamorphism. One of the purposes of this study is to understand how potential fluids, streaming upwards from the crust-mantle boundary, could influence gradations in mineral chemistry and REE distribution along the traverse.
Mineralogical, petrological, and geochemical regional study of oxide-sulfide and silicate mineral relations in high grade rocks (charnockites, two-pyroxene granulites, and metagabbros) from the Nilgiri Massif, southern India
Mineralogical, petrological, and geochemical regional study of oxide-sulfide and silicate mineral relations in high grade rocks (amphibolite-facies rocks, charnockites, and metagabbros) from the Madras Block, southern India
Mineralogical, petrological, and geochemical regional study of oxide-sulfide and silicate mineral relations in high grade rocks (amphibolite-facies rocks, charnockites, and metagabbros) from the Coorg Block, southern India
Mineralogical, petrological, and geochemical regional study of oxide-sulfide and silicate mineral relations in high grade rocks (amphibolite-facies rocks, charnockites, and metagabbros) from the Biligiri-Rangan Hills Block, southern India
LA-ICPMS study of fluorapatite, garnet, amphibole, and clinopyroxene (Y+REE) chemistry across a lower crustal, fluid-activated, localised orthopyroxene-bearing dehydration zone, Söndrum stone quarry, SW Sweden.
A regional study investigating the role of CO2-rich and H2O-rich fluids during the genesis and evolution of a co-genetic granite and magmatic charnockite association as well as their influence on the surrounding amphibolite-facies gneiss, country rock, Varberg-Torpa charnockite-granite association, SW Sweden.
The role of CO2-rich fluids in the formation of charnockite patches in a granitic magma during emplacement of the Weinberg granite, north central Austria.
Comprehensive study of the influence of fluids on apatite mineral chemistry (focusing on Cl, F, OH, CO3 chemistry) in the lower crust and upper mantle.
Experimental dehydration of granitoid rocks, under granulite-facies conditions, utilizing both partial melts and low H2O activity fluids including both CO2 and supercritical NaCl-KCl brines.
Experimental formation of simple symplectites of K-feldspar and albitic plagioclase at the quartz-plagioclase interface utilizing both partial melts and low H2O activity fluids.
Kiruna-type magnetite-apatite ore iron-oxide apatite (IOA) deposits
Kiruna magnetite-apatite ore deposits are being studied world wide with regard to their origins, crystallization history, fluid history, and subsequent evolution over time. These deposits include:
Kirunavaara magnetite-apatite ore deposit, Kiruna, northern Sweden
Mineralogy, petrology, and geochemistry IOA deposit - skarn relationships in the Middle-Lower Yangtze River Metallogenic Belt, eastern China
Grängesberg magnetite-apatite ore deposit, central Sweden
Esfordi, Chogart, Chadormalu, and Se-Chahun magnetite-apatite ore deposits, Bafq region, central Iran
Mineville magnetite-apatite ore deposit, Adirondacks, New York, USA
Pea Ridge magnetite-apatite ore deposit, Arkansas, USA
Field projects cover a variety of different metamorphic and igneous terranes and associated rock types on a planet wide scale. In general, many of these projects are closely integrated with experimental work involving silicate, phosphate, oxide, and sulfide minerals.
Field projects include:
Granulite- to amphibolite facies traverse of lower late Archean crust, Shevaroy Block, Tamil Nadu, south India.
The mesoproterozoic Steenkampskraal rare-earth element monazite-apatite deposit, Namaqualand, South Africa
Late Archean granulite-facies crust from the Nilgiri Block, Namakkal Block, Coorg Block, Biligiri-Rangan Hills Block, and Madras Block, south India.
Arrested charnockites, Kondalite Zone, Kerala, southern India and West Cape Province (Namaqualand, South Africa).
Orthopyroxene-bearing and clinopyroxene-bearing localized dehydration zones, Söndrum stone quarry, Halmstad, Kattegat coast, southwest Sweden.
Varberg-Torpa charnockite-granite association, Varberg, Kattegat coast, southwest Sweden
Arrested charnockite patches in the Weinberg granite, northern Austria.
Calcsilcate rocks and leucosomes, Halmstad, Kattegat coast, southwest Sweden.
Apatite, biotite, and clinopyroxene as tracers for metasomatic processes in nepheline clinopyroxenites of Uralian-Alaskan-type complexes in the Ural mountains, Russian Federation.
Studies of alumino-silicate minerals and apatite, Bamble Sector, southern Norway.
Alkaline-carbonatite magmatism, Alnö, Sweden.
Studies of accessory minerals, Ivrea-Verbano Zone, northern Italy.
Regional scale, pluton-driven, high-grade metamorphism in the Archean Minto block, northern Superior province, Canada.
Granulite-facies xenoliths from the Eger rift zone, northern Czech Republic.
Fellow of the American Mineralogical Society