+
Welcome to Robert Frei's personal homepage!

    Contact information
                       
                                    Robert Frei                                    
 


Professor for Igneous Petrology
Institute of Geography and Geology

 Leader of the Research Group of Geochemical, Minearlogical and Petrological Earth Sciences
Leader of the Danish Center for Isotope Geology
   University of Copenhagen
 Øster Voldgade 10
 DK-1350 Copenhagen K, Denmark

 Tel     -xx45 35 32 24 50
Fax    -xx45 35 32 24 40
e-mail: robertf@geol.ku.dk


 click one of the topics below....  






CV summary

1989
 Diploma (Masters) in Mineralogy and Petrology
Swiss Federal Institute of Technology (ETH) Zurich, Switzerland
1993
 Ph.D., Dr. Sc. Natw.
Swiss Federal Institute of Technology (ETH) Zurich, Switzerland
1993-1997
 Assistant Professor
Institute for Mineralogy and Petrology, Group of  Isotope Geology
University of Bern, Switzerland
1998
 Habilitation, PD Dr. (Privat-Docent), University of Bern, Switzerland
1997-1999
 Laboratory manager, Danish Center for Isotope Geology
Geological Institute, University of Copenhagen, Denmark
1999 -
Professor for Igneous Petrology, Leader of the Research Group of Geochemical, Minearlogical and Petrological Earth Sciences, Institute of Geography and Geology, University of Copenhagen, Denmark
Leader of the Danish Center for Isotope Geology
back to first page



Research interests
General interests
Radiogenic isotope geochemistry - geochronology - use of isotope tracers

                                                     
Specific interests
- Early Earth - Hadean Eon; use of isotopic tracers
    see a relevant article , and another one
- Early - Late Archean crust-mantle differentiation / formation processes
   see one of my articles , and another one

- Development of alternative dating techniques (for example: lead stepwise leaching )
   see one of my articles

- Ore formation processes, using isotopes as proxy for tracing the origin / source of metals
- Porphyry copper deposits: see one of my articles;
- Epigenetic gold deposits: see one of my articles ;
- Banded Iron Formations : see one of my articles ; and another one
- Re-Pt-Os isotope systematics of mantle and core-mantle interaction processes: see one of my articles ;
- PGE alloys and their role for tracing mantle geodynamics : see one of my articles ; see a typical PGE grain
- PGE systematics of impact structures, f.e. the Cretaceous-Tertiary border: see one of my articles
- Non-traditional stable isotope tracers applied to palaeoredox systems and climatic changes in the past
back to first page


SNF frame project 2002 - 2009

Description of the project

This 3-year frame application is aimed at seeking financial support for an extensive research program to study some main and important reservoirs on Earth (hydrosphere, oceanic crust and sub-continental mantle) and their genesis and evolution through time, restricted to the Early – to late Archean (2.6 – 3.8 Ga) time period. The project is planned to simultaneously address key questions within 3 Archean blocks with very similar magmatic and metamorphic histories, which are worked out in great detail already. The complexity of the topics and the multi-systematic approaches, mainly using modern and recently developed isotope systems, in conjunction with a palette of relevant trace elemental data, requires a combination of the outcomes of a number of master and Ph.D. students projects designed to fit the general topic. The project allows for an optimization of field work and sampling campaigns to satisfy a relevant and appropriate sample base for the individual studies. I anticipate that the extent of the project will requires an extension beyond the first application period.

1.    Background and aims

The project can be subdivided into two parts, designed at thematically and logistically to complement each other.

Part I

Lu-Hf, Sm-Nd, U-Pb, Re-Os, Fe isotopes and PGE abundances in Banded Iron Formations as tracers for the evolution of global seawater, weathering of continents and emergence of life through time – indications from the W Greenland, SW Montana / Wyoming and Southern Africa (Zimbabwe, Botswana, Congo) Archean blocks.

Natural radiogenic isotope tracers in seawater, such as 87 Sr, 143Nd, 208,207, 206Pb and 187 Os are of particular value in the study of ocean circulation and mixing. This usefulness derives from their very different residence times in seawater and therefore their contrasting behavior on the timescales of ocean circulation, and mixing. Thus, Sr with a long residence time of 2 Ma is isotopically well-mixed globally in the oceans. Although global mixing timescales for the ocean are usually not specified, it is assumed that substantial mixing accompanies ocean circulation which has a timescale around 1000 a. This is several orders of magnitude shorter than the timescale for Sr residence inn the oceans. On the other hand, Os, Nd and Pb which have shorter residence times, estimated at ~10'000,  ~1800 and ~80 a respectively, are not well mixed in the oceans, and their isotopic distribution reflects erosional and hydrothermal inputs as well as different advective length scales accompanying ocean circulation (e.g., O´Nions et al., 1998, Frank et al., 1999). The aspects of Sr, Nd, Os and Pb behavior in seawater has been exploited over a number of years both in studies of the provenance of these elements and also in the investigation of water mass movements. Various attempts have been made to reconstruct secular changes in seawater Nd at specific points in the oceans, notable amongst which are the studies of Nd in foraminifera and their coatings and hydrogeneous ferromanganese crusts. These studies all focus on recent or young paleo-water systems, but studies of very old water systems are limited by the scarcity of appropriate geological materials that record and depict seawater compositions. Banded Iron Formations (BIFs) are suitable for this purpose, basically because they record slow sedimentation processes in seawater and because they occur throughout the Precambrian. With the progress in actually dating BIFs it has become clear that there is a considerable age spread also among Proterozoic iron formations (e.g., Gole and Klein, 1981). Together with the observation of rather abundant iron-formations in the Archean, a considerable modified picture has evolved for the relative abundance of iron formations vs. geological age. The most striking difference among Precambrian banded iron-formations is between those that are granular and oolitic and those that are laminated. Such structures reflect different physical environments of deposition but, as shown by their similar bulk composition and late diagenetic mineral assemblages, the chemical process leading to the formation of both granular and laminated iron formations must have been essentially the same. REE distributions in Precambrian ion formations show evidence of evolving oxidation states for the elements europium and cerium (e.g., Fryer, 1976)

Banded Iron Formations are the most abundant type of chemical sediment precipitated in the Archean and Proterozoic. These deposits are typically laminated, with alternations of Fe-rich and Si-rich layers. Current models on the origin of BIFs suggest that the thick, laterally extensive BIF deposits, such as the Hamersley Iron Formation, Western Australia (approximately 2.5 Ga), formed on the continental shelf of an Archean craton. Iron mineralization presumably took place in the upper water column, occurring along a chemocline between upwelled, reducing, metal-rich hydrothermal waters and oxygenated surface waters. It is unclear what proportion of the ferric iron was initially produced via photochemical processes, anoxygenic photosynthesis, photodissociation of atmospheric water vapour or oxygenic photosynthesis. The end result of any of these modes of oxidation, however, would be the precipitation of ferric hydroxide in the water column, its sedimentation and the systematic accumulation of iron-rich sediment. It is speculated that microorganisms may have facilitated the precipitation of the progenitor iron hydroxide sediment by serving as passive nucleation sites, much as they do today in hydrothermal aqueous solutions.

High precision iron isotope measurements of terrestrial material have shown no mass-dependent isotope fractionation for igneous rocks (Beard et al., 1999; Beard and Johnson, 1999). First data however indicate, that Fe-Mn nodules and banded iron formation have iron isotope compositions that vary over a relatively wide range, from d56Fe = +0.9 to –1.2 permil (Beard et al., 1999). These isotopic fractionations are interpreted to reflect biological effects, and illustrate the great potential of Fe isotope studies for investigating modern and ancient biological processes. They are of particular interest in the study of Archean BIFs, as they may have important implication as to the emergence of life and may contribute to the general debate regarding the oxidation processes needed to precipitate the vast amount of iron in BIFs during the Archean.

Three different sources for iron in BIFs have been proposed: a) Fe carried in solution by rivers into the oceans, b) Fe leached from the suspended loads of rivers after deposition in the deeper, more reducing portion of the oceans, and c) a volcanic –exhalative source of Fe suggested from the intimate association between Algoma-type BIFs and volcanic rocks. An analogue of a volcanic-exhalative source could be the hydrothermal systems operating along mid-ocean ridges today.

The osmium isotopic composition of seawater reflects a balance of input from radiogenic continental material through erosion, and an unradiogenic mantle-type signature derived either from the alteration of oceanic crust, erosion of ultramafic rocks, or dissolution of micrometeorite material. Consequently, this isotopic system potentially provides a record of the relative changes in these sources over time. The Os isotopic composition of seawater has, like Sr, evolved towards radiogenic values through much of Cenozoic time and this has been attributed to intensified continental weathering (e.g., Peucker-Ehrenbrink et al., 1995). Due to the short water residence time, the Os isotopic system has the capability to respond, in phase, to short-term fluctuations in input. In contrast, the longer residence time for Sr will both dampen and delay any response to changes in continental input. For example, variations in the Os isotopic composition of seawater during glacial-interglacial intervals have been attributed to changes in continental input, and cannot be resolved in the Sr isotope record. Thus, the Os isotopic system potentially offers a highly sensitive and distinct record of chemical weathering of the continents.

Many of the oldest and most depositionally complete hydrogenetic ferromanganese crusts are recognized to be enriched in Pt, but the source of this enrichment is debated. Some of the Pt is contained in Fe-, Ni-, and Pt-rich spherules in ferromanganese crusts, and elevated chondrite normalized (PGE/Ir)N ratios indicate a general enrichment of PGE in ferromanganese materials, also with respect to seawater ratios. Furthermore, osmium isotopic ratios indicate a non-chondritic source for the PGE. Much of the Pt and Ir contained in the ferromanganese crusts correlate with Fe-rich layers. Results of seawater-ferromanganese oxide adsorption experiments using 191Pt and 192Ir suggest that Pt is preferentially scavenged by FeOOH when compared to Ir, suggesting a seawater source for the enrichment. If this is true, then BIFs should theoretically show the same characteristics. The entire PGE pattern, combined with Os isotopes, will certainly give clues to the origin of PGE in these sediments and may have a central impact on the debate regarding long-term Pt/Os enriched reservoirs that are recycled into the mantle and are necessary to explain supra-chondritic 186Os/188Os observed in some plume-derived magmas and PGE alloys (e.g., Brandon et al., 1997; Walker et al., 1997; Lassiter and Hauri, 1998; Bird et al., 1999; Puchtel and Huyamun, 2000, and others).

Part II

Lu-Hf, Sm-Nd, U-Pb and Re-Os isotopes in mafic-, ultramafic (layered) and kimberlite intrusions and granitoid-related mineralizations as tracers for the evolution of sub-continental lithosphere: A comparison between the Archean blocks of W Greenland, SW Montana / Wyoming and Southern Africa.

Due to their highly siderophile and generally compatible nature, platinum group elements (PGE = Ru, Rh, Pd, Os, Ir, Pt) are a powerful tool for studying processes of the Earth’s accretion, core-mantle differentiation, mantle evolution and magma genesis. In addition, the development and application of the siderophile element radiogenic systems, 187Re-187Os and 190Pt-186Os provide both tracer and chronological information on differentiation processes affecting these elements. However, high quality studies of PGE concentrations and isotopic compositions still cover a limited range of Archean mantle samples. The behavior of PGEs during partial melting and crystal fractionation can be studied from PGE compositions of mantle-derived lavas such as basalts and komatiites, a major constituent of Archean greenstone belts. Komatiites can be used as indicators of mantle source PGE composition since these lavas are sulfide-unsaturated primary melts. Their abundances can be used to calculate Pt/Os and Re/Os composition of Archean oceanic crust. This is imperative for the understanding of coupled 186,187Os enrichments observed in some modern plume systems, which presently is a subject of intensified research (e.g., Brandon et al., 1997; Bird et al., 1999, and others). High Pt/Os reservoirs necessary to reconcile the Os isotopic enrichments are the outer core and presumably old oceanic crust, which through subduction-related processes is recycled into the mantle. The Os isotopic system is capable of distinguishing between crustal vs. enriched sub-continental lithospheric mantle in mantle sources, and thus will be able to record ancient Re-depletion and Pt enrichment events. In combination with PGE-data of chromites from ultramafic (layered) intrusive bodies, which are a rich source of information on the origin and evolution of the parent magma in the sub-continental lithospheric setting, a detailed picture of the early to late Archean oceanic crust and mantle beneath the 3 selected Archean blocks can be obtained. Modeling of these reservoirs and their temporal evolutions is essential in the understanding of ancient and recent hot mantle plumes and their interaction with the crust during ascent. Furthermore, the parallel study of these reservoirs, on which information is being gathered from 3 similar Archean blocks, allows for a global and long-term reconstruction of the composition of the oceanic crust and sub-continental mantle since the Pangea supercontinent setting.

 

FNU big frame project 2007 - 2009
 

Chromium(Cr)-molybdenum(Mo)-cerium (Ce) stable isotope tracing of paleoredox processes in ancient seawater

 

An application for funding of projects of excellence in research and a proposed collaboration and between

 

Institute of Geography and Geology, University of Copenhagen

and

Department of Geology, Kent State University, Ohio, USA

and

 Departamento de Geología of the Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay

and

Institute of Mineralogy, University of Würzburg, Germany

and

Department of Geological Science, University of Cape Town

Rondebosch, South Africa

 

.  

 1. Summary

 

The basic conditions for the most important aspects of modern life on Earth have been shaped as early as in Precambrian times. These include the origin of life, the evolution of continental crust, the oxygenation of the atmosphere and the formation of mineral deposits. All of these aspects appear to be interrelated but the various feed-back mechanisms that controlled the relationships between life´s evolution, plate tectonic processes, paleoclimate and distribution of metals between hydrosphere and geosphere  throughout the critical periods of the Precambrian remain highly speculative. One of the more important questions concerns the timing and cause of the rise of atmospheric oxygen. Seawater is the reservoir of choice to trace atmospheric oxygen fluctuations, as redox processes associated with them are recorded in (chemical sediments. A number of redox tracers have already been widely applied to answer the above questions, but a clear definition of the actual chemical conditions is difficult to assess. Only a combination of several redox-sensitive tracers will enable further more precise characterization of the oxygenation states of ancient seawater. Modern isotope geochemistry now enables to assess fractionation of isotopes of elements that earlier were thought to have stable isotopic compositions. These include iron, molybdenum, and chromium. The aim of this research program is to evaluate the feasibility of these modern tracers in unraveling information about the redox processes in surface and bottom waters of oceanic basins, that were formed during major changes of atmospheric oxygen, i.e., during Paleoproterozoic and Neoproterozoic times. The intention is to supplement the information from these tracers with another very interesting element, namely cerium, which is redox sensitive and which is typically used in marine studies for identifying the strip-off of oxidized Ce into manganese crusts, a process which today is extremely effective. The PI´s idea is to add the isotopic dimension to this and try to define possible isotopic fractionation of Ce isotopes during these processes, a tool which in combination with results from the other tracers, has a high potential to more precisely characterize the subtle redox changes during these periods in Earth´s history.

 

2. Project description

 Background

 The evolution oft the Earth´s atmosphere is essentially the story of atmospheric oxygen. Virtually every realm of the Earth sciences – biology, geology, geochemistry, oceanography, and atmospheric science, is needed to piece together an understanding of the history of oxygen. Over the past decade, new data from these fields has shown that there were two significant increases in atmospheric oxygen levels at around 2.4-2.3 Ga and 0.8-0.6 billion years ago, respectively. Throughout Earth´s history, oceanic sulfate concentrations appear to have increased in accord with greater O2 levels, while levels of methane, a strong greenhouse gas, may have inversely mirrored O2. Both oxic transitions occurred in eras characterized by “Snowball Earth” events and significant disturbances in the carbon cycle, perhaps associated with increases in O2 and losses of methane. To understand what controlled the oxygenation of the atmosphere, it is necessary to determine how O2 is consumed on geologic time scales through reaction with reductants released from the Earth´s crust and mantle. There was apparently a long delay between the appearance of oxygenic photosynthesis and oxygenation of the atmosphere, and a plausible explanation is that excess reductants scavenged photosynthetic O2 from the early atmosphere. However, a quantitative understanding of how and why O2 became abundant on our reducing planet is still lacking. Thus, the study of the early atmosphere, though geological records preserved in sediments, remains a frontier field with much to be discovered.

What is the evidence of the Paleoproterozoic rise of O2 and its effects?

 Paleosols, detrital grains and red beds suggest very low levels of O2 before ~2.4 Ga. Well-preserved paleosols (lithified soils) provide estimates of the oxygen partial pressure based on iron and rare-earth element geochemistry. Iron was leached form the soils before the ~2.4 Ga oxic transition but not afterwards because anoxic rainwater flushes soluble ferrous iron (Fe2+) through a soil, whereas oxygenated rainwater produces insoluble and immobile ferric iron (Fe3+). Cerium (Ce3+ and Ce4+) can be used similarly. Other evidence comes from detrital grains, which are sedimentary minerals that never completely dissolve in weathering. Detrital grains in pre-2.4 Ga riverbeds commonly contain reduced minerals that would only survive at low pO2. Grains of pyrite (FeS2), uraninite (UO2) and siderite (FeCO3) place upper bounds on Archean pO2. The roundness of such grains shows that they were transported long distances in aerated waters. A further constrain is the appearance of Proterozoic continental redbeds. Redbeds are sedimentary sandstones derived form wind-blown or river-transported particles coated with red-colored iron oxides, usually hematite (Fe2O3), which formed after atmospheric oxygenation.

Evidence can also be deducted and read form the marine environment. Banded iron formations (BIFs) appear from the start of the geologic record but decline in abundance through the Paleoproterozoic and disappear after ~1.8 Ga, consistent with redox change. Trace and rare earth element patterns in BIFs indicated hydrothermal input of ferrous iron, which would have remained in solution if deep waters of the Archean ocean were anoxic. Fe2+ is hypothesized to have been transported to shallow continental shelves where oxidation precipitated ferric iron. BIFs presence for ~0.5 b.y. after the rise of O2 has been used to argue that the deep ocean was not oxygenated until 1.8 Ga. It is now widely accepted that the deep ocean in fact remained anoxic until  Neoproterozoic times, with Fe2+ being removed by precipitation of pyrite derived form sulfate reducing bacteria. Isotopes of carbon, sulfur and iron in marine sediments indicate major changes in the Paleoproterozoic. For example, very positive d13Ccarb excursions occur in the Paleoproterozoic, the same era as the rise of O2, and are possibly associated with enhanced organic burial. The sulfur isotopic record indicates significant 32S enrichment only to become widespread after 2.3 Ga, suggesting more available sulfate and hence oxygen. Changes in iron isotope also provide evidence for an oxic transition. Negative d56Fe in pyrites formed before 2.3 Ga suggest an anoxic deep ocean, rich in Fe2+, with fractionating loss of iron to BIFs.

 The Neoproterozoic second rise of oxygen is nicely defined by the 32S-enrichment that can be explained if sulfide was re-oxidized at the sediment-water interface to SO42- and cyclically reduced, increasing the isotope fractionation. Possible, O2 increased to the point where it penetrated marine sediments, ending a deeply sulfidic ocean. A second rise in O2 levels is important for understanding the evolution of animals. In the Neoproterozoic, like in the Paleoproterozoic, low-latitude glacial deposits occur along with extraordinary d13C excursions in carbonates perhaps associated with a second rise of O2.

 

Goals

The aim with this study is to widen the field of redox tracing of ancient seawater, using new stable isotope systematics of chromium, molybdenum and cerium, all of which being highly sensitive to oxidation-reduction processes. The chemical separation techniques and mass spectrometrical measurement procedures first have to be developed, tested and calibrated, and then it is planned to apply these tracers to specifically suitable sedimentary profiles from certain, previously investigated Paleoproterozoic and Neoproterozoic rock sequences, respectively. The collaboration with Prof. H. Frimmel, Prof. P.S. Dahl and Dr. C. Gaucher (all active in the field of marine and crustal geochemistry) enables precise and accurate sampling of relevant profiles in southern America, southern Africa and continental USA, and a comprehensive multi-directional assessment of combined data sets obtained during this study.

 

This project is designed as a truly collaborative effort to characterize important Neoproterozoic and Paleoproterozopic sequences in South America, South Africa and Northern America. A particular interest is to combine the information from analogous profiles in Uruguay (Dom Feliciano) and its counterparts in southern Africa (Gariep Belt), both representing deposits of the PAN-African period. Specifically, much emphasis is placed on the delineation of the importance of world-wide glaciation epochs on the seawater-climate interrelationships, and particularly their effects of the deposition of iron- and carbon-rich sequences. All collaborators have been and still are heavily involved in respective research within their own institutions. The profiles have all been well characterized, both with respect to their ages and their major and trace elemental compositions. The research proposed herein is heavily based on this information.

 

In addition, through the purchase and installation (during April/May 2007) of a new generation thermal ionization mass spectrometer at the GGI with extended mass resolution it will be possible to perform high precision isotopic analyses of low mass elements such as Cr with simultaneous correction possibilities for interfering masses such as produced by Fe, V, and Ti. This project takes full use of this peculiar features.

The 3 main external collaborators are.

 

1. Prof. H.E. Frimmel

Department of Geological Sciences

Room 501 Louis Ahrens Building, Library Road

University of Cape Town

Rondebosch, 7700, RSA

 

and

 

Mineralogisches Institut
Universität Würzburg
Am Hubland
D-97074 Würzburg
Germany

 

2. Dr. C. Gaucher

Facultad de Ciencias - Universidad de la República

Iguá 4225 esquina Mataojo (Malvin Norte)Código postal11400
Montevideo – URUGUAY

 

3. Prof. P.S. Dahl

Department of Geology

Kent State Univeristy

Kent, Ohio 44242, USA

 


back to first page


Courses

Code Name
 Description
 ECTS points
Geochemistry
Block 1
 		Part: Earth Systems







 		The Earth System part is meant as an introduction to the formation of the solar system and the terrestrial planets in particular. The evolution of the Earth and its differentiation is looked at from the perspective of important geochemical tools, including trace element implications and respective isotope tracer systems. The course follows an evolving compendium which can be downloaded from the server as a pdf-file. 7.5
total
course
Lithospheric
Geology and Geochemistry
Block  6
 		Part: Radiometric Dating
 		In this part of the course, an overview of different dating methods is given. These include direct, indirect and relative approaches, which are applicable to igneous, metamorphic and sedimentary geochronological problems. The focus will be on the application of radiogenic isotope systems, which allow for the calculation of direct and model ages. the course follows an evolving compendium which can be downloaded from the server as a pdf-file..
7.5
total
course
Laboratory
course
 		Introduction to element separation techniques and mass spectrometry This 3-weeks block course is designed as an introduction to the diversity of element separation techniques for isotopic analyses and to the use of the thermal ionization mass spectrometer at the Geological Institute. The participants are familiarized with the rules and working conditions in the clean laboratories and the principles of isotopic ratio measurements. The course is based on a step-by-step sample string-line procedure.
5
Master
course
 Deep Earth
Part: Formation of the Earth and Hadean Eon

 In this part of the ground course focus will be on the formation
of the solar system and the Earth. Since the direct geological record is not available, the use of geochemical tracers are essential for constraining the history and evolution of Earth during its very early existence.
15
total
ground
course

back to first page



Selected publication s

 

2008

Frei, K.M., Frei, R., Mannering, U., Gleba, M., Nosch, M.L., and Lyngstrøm, H. (in press)  Provenance of ancient textiles – a pilot study evaluating the Sr isotope system in wool. Archaeometry

Frei, R., Dahl, P.S., Duke, E.F., Frei, K.M., Hansen, T.R., Frandsson, M.M. and Jensen, L.A. (in press)  Trace element and isotopic characterization of Neoarchean and Paleoproterozoic iron formations in the Black Hills (South Dakota, USA): Assessment of chemical change during 2.9-1.9 Ga deposition bracketing the 2.4-2.2 Ga first rise of atmospheric oxygen. Precambrian Research

Stendal, H.  and Frei, R. (in press) Mineral occurrences and their timing related to the Caledonian orogeny. Geological Society of America, Special Bulletin.

Kalsbeek, F., Thrane, K., Higgins, A.K., Jepsen, H.F., Leslie, A.G., Nutman, A.P., and Frei, R. (in press) Polyorogenic history of the East Greenland Caledonides. Geological Society of America, Special Bulletin.

Appel. P.W.U., Polat, A., and Frei, R. (in press) Early Archean (3.8-3.7 Ga) ocelli with plagiogranitic composition, the Isua greenstone belt, West Greenland: Evidence for liquid immiscibility in a supra-subduction zone setting. Lithos

 Polat, A., Frei, R., Appel, P.W.U., Dilek, Y., Fryer, B., and Ordonez-Calderon, J.C. (2008) The origin and compositions of Mesoarchean oceanic crust: evidence from the 3075 Ma Ivisaartoq greenstone belt, southern West Greenland. Lithos, v. 100, 293-321.

2007

Oyhantçabal, P., Siegesmund, S., Wemmer, K., Frei, R., and Layer, P. (2007) Post-collisional transition from calc-alkaline to alkaline magmatism during transcurrent deformation in the southernmost Dom Feliciano Belt (Braziliano-Pan African, Uruguay). Lithos, v.98, p.141-159.

Mondal, S.K., Frei, R., and Ripley, E.M. (2007) Os isotope systematics of Mesoarchean chromitite – PGE deposits in the Singhbhum Craton (India): Implications for the evolution of subcontinental lithospheric mantle. Chemical Geology, v.244, p. 391-408.

Juul-Pedersen, A., Frei, R., Appel, P.W.U., Persson, M., and Konnerup-Madsen, J. (2007) A shear zone related greenstone belt hosted gold mineralization in the Archean of West Greenland. A petrographic and combined Pb and Rb-Sr isotope geochemical characterization. Ore Geology Reviews, v. 32, p. 20-36.

Frei, R., and Polat, A. (2007) Source heterogeneity for the major components of ~3.7 Ga Banded Iron Formations (Isua Greenstone Belt, Western Greenland): Tracing the nature of interacting water masses in BIF formation. Earth and Planetary Science Letters, v. 253, p. 266-281.

Polat, A., Appel, P.W.U., Frei, R., Pan, Y., Dilek, Y., Ordonez-Calderon, J.C, Fryer, B., Hollis, J.A. and Raith, J.G. (2007) Field and geochemical characteristics of the Mesoarchean (~3075 ma) Ivisaartoq greenstone belt, southern West Greenland: Evidence for seafloor hydrothermal alteration in a supra-subduction oceanic crust. Gondwana Research, v.11, p.69-91.

2006

Stendal, H., Secher, K., and Frei, R. (2006) 207Pb-206Pb dating of magnetite, monazite and allanite in the central and northern Nagssugtoqidian orogen, West Greenland. Geological Survey of Denmark and Greenland Bulletin, v. 11, p. 101-114.

Stendal, H., Frei, R., and Stensgaard, B.M. (2006) A lead isotope study of an Archaean gold prospect in the Attu region,  Nagssugtoqidian orogen, West Greenland. Geological Survey of Denmark and Greenland Bulletin, v. 11, p. 53-60.

Peng, B., Frei, R., and  Xianglin, T.T. (2006) Nd-Sr-Pb isotopic geochemistry of scheelite from the Woxi W-Sb-Au deposit, Western Hunan: implications for sources and evolution of ore-forming fluids. Acta Geologica Sinica, v.80, p. 561-570.

Mercolli, I., Briner, A.P., Frei, R., Schoenberg, R., Naegler, T.F., Kramers, J. and Peters, T. (2006) Lithostratigraphy and geochronology of the Neoproterozoic crystalline basement of Salalah, Dhofar, Sultanate of Oman. Precambrian Research, v. 145, p. 182-206.

Steenken, A., Siegesmund, S, Lopez de Luchi, M., Frei, R., and Wemmer, K. (2006) Neoproterozoic to Early Palaeozoic events in the Sierra de San Luis: implications for the Famatinian geodynamics in the Eastern Sierras Pampeanas (Argentina). Geological Society of London Special Publications, v. 163, p. 965-982.

Kalsbeek, F, and Frei, R.  (2006) The Mesoproterozoic Midsommersø dolerites and associated intrusions, North Greenland: crustal melting, contamination and hydrothermal alteration. Contributions to Mineralogy and Petrology, v. 152, p. 89-110.

Mondal, S.K., Ripley, E.M., Li, C., and Frei, R. (2006) The genesis of  Archean chromitites from the Nuasahi and Sukinda massifs in the Singhbhum Craton, India. Precambrian Research, v. 148, p. 45-66.

Alpaslan, M., Boztuğ, D., Frei, R., Temel, A., and Kurt, M.A. (2006) Geochemical and Pb-Sr-Nd isotopic composition of ultrapotassic volcanic rocks from the extension-related Camardi-Ulukişla basin, Niğde Province, Central Anatolia, Turkey. Journal of Asian Earth Sciences, v.27, p. 613-627.

Dahl, P.S., Hamilton, M.A., Wooden, J.L., Foland, K.A, and Frei, R. (2006) 2480 Ma mafic magmatism in the northern Black Hills, South Dakota: a new link connecting the Wyoming and Superior cratons. Candian Journal of Earth Sciences, v. 43, p. 1579-1600.

Stendal, H., Toteu, S.F., Frei, R., Penaye, J., Njel, U.O., Bassahak, J., Nni, J., Kankeu, B., Ngako, V., and Hell, J.V. (2006) Provenance of rutile from the Yaounde region, Neoproterozoic Pan-African belt in southern Cameroon (Central Africa). Journal of African Sciences, v.44, p. 443-458.

Frei, R., Gervilla, F., Meibom, A., and Proenza, J.A. (2006) Os isotope heterogeneity of the convecting upper mantle: The Mayari-Baracoa Ophiolitic Belt (eastern Cuba). Earth and Planetary Science Letters, v.241, p.466-476.

2005

Polat, A., Appel, P.W.U., Frei, R ., Pan, Y., Dilek, Y., Calderon, J.C.O., Fryer, B., and Raith, J.G. (subm.) Field and geochemical characterisitics of the Mesoarchean (~3075 ma) Ivisaartoq greenstone belt, southern West Greenland: Evidence for seafloor hydrothermal alteration in a supra-subduction oceanic crust. Gondwana Research .

Steenken, A., Siegesmund, S, Lopez de Luchi, M., Frei, R., and Wemmer, K. (subm.) New constraints on the Famatinian geodynamic evolution of the proto-Andean margin of Gondwana (Sierra de San Luis / Argentina). Geological Society of London Special Publications.

Kalsbeek, F, and Frei, R.  (subm.) The Mesoproterozoic Midsommersø dolerites and associated intrusions, North Greenland: crustal melting, contamination and hydrothermal alteration. Contributions to Mineralogy and Petrology

Mondal, S.K., Frei, R ., Ripley, E.M., and Glascock, M.D. (subm.) Trace element and Os isotopic compositions of 3.2 Ga ultramafic-mafic rocks and associated chromitite-platinoid deposits in the Singhbhum Craton, India: implications for source and tectonic setting. Earth and Planetary Science Letters

Mondal, S.K., Ripley, E.M., Li, C., and Frei, R. (subm.) The genesis of  Archean chromitites from hte Nuasahi and Sukinda massifs in the Singhbhum Craton, India. Precambrian Research.

Stendal, H., Secher, K., and Frei, R. (subm.) Palaeoproterozoic events in central west Greenland (66˚N-70˚15’N – Pb isotopic results. Geological Survey of Denmark and Greenland Bulletin .

Stendal, H.  and Frei, R. (subm.) Mineral occurrences and their timing related to the Caledonian orogeny. Geological Society of America, Special Bulletin.

Kalsbeek, F., Thrane, K., Higgins, A.K., Jepsen, H.F., Leslie, A.G., Nutman, A.P., and Frei, R. (subm.) Polyorogenic history of the East Greenland Caledonides. Geological Society of America, Special Bulletin.

Alpaslan, M., Boztuğ, D., Frei, R. , Temel, A., and Kurt, M.A. (in press) Geochemical and Pb-Sr-Nd isotopic composition of ultrapotassic volcanic rocks from the extension-related Camardi-Ulukişla basin, Niğde Province, Central Anatolia, Turkey. Journal of Asian Earth Sciences.

Dahl, P.S., Hamilton, M.A., Wooden, J.L., Foland, K.A, and Frei, R. (in press) Evidence for 2480 Ma mafic magmatism in the easternmost Wyoming craton (Black Hills, SD), with implications for the 2900-2500 Ma configuration of a Neoarchean supercontinent. Candian Journal of earth Sciences.

Stendal, H., Toteu, S.F., Frei, R. , Penaye, J., Njel, U.O., Bassahak, J., Nni, J., Kankeu, B., Ngako, V., and Hell, J.V. (in press) Proveneance of rutile from the Yaounde region, Neoproterozoic Pan-African belt in southern Cameroun (Central Africa). Journal of African Sciences

Gervilla, F., Proenza, J.A., Frei, R., Gonzales-Jimenez, J.M., Garrido, C.J., Melgarejo, J.C., Meibom, A., Diaz-Martinez, R., and Lavaut, W. (in press) Distribution of platinum-group elements and Os isotopes in chromite ores from Mayari-Baracoa Ophiolitic Belt (eastern Cuba). Contributions to Mineralogy and Petrology 

Frei, R., Gervilla, F., Meibom, A., and Proenza, J.A. (subm.) Os isotope heterogeneity of the convecting upper mantle: The Mayari-Baracoa Ophiolitic Belt (eastern Cuba). Earth and Planetary Science Letters

Mondal, S.K., Ripley, E.M., Li, C., and Frei, R. (in press) Mineralogical and Os isotopic constraints on the petrogenesis of the 3.1 Ga chromitite-bearing ultramafic bodies of Nuashi and Sukinda massifs (Orissa) in the Singhbhum Craton, India. Precambrian Research

Liebetrau, V., Eisenhauer, T., Frei, R., Kronz, A., Bock, B., Hansen, B.T., and Leipe, T. (2004) Radiometric growth rate and Pb isotope evolution of Mn/Fe precipitates from the SW-Baltic Sea. Zeitschrift fuer Angewandte Geologie, special issue (Sonderheft 2), p. 177-197.

Dahl, P.S., Hamilton, M.A., Jercinovic, M.L.,Terry, M.P., Williams, M.L., and Frei, R. (2005) Comparative isotopic and chemical geochronometry of monazite, with implications for U-Th-Pb dating by electron microprobe: An example from metamorphic rocks of the eastern Wyoming Craton (U.S.A.),. American Mineralogist, v. 90, p. 619-638.

Polat, A.and Frei, R.(2005) The origin of early Archean banded iron formations and of continental crust, Isua, southern West Greenland. Precambrian Research, v. 138, p.151-175. Polat and Frei-Prec.Res.-2004-1

Frei, R. , and Rosing, M.T. (2005) Search for traces of the late heavy bombardment on Earth – Results from high precision chromium isotopes. Earth and Planetary Science Letters, v.205, p.28-40.  Frei and Rosing - EPSL-2005-1

2004

Alpaslan, M., Frei, R., Boztuğ, D., Kurt, MA. and Temel A. (2004, Geochemical and Pb-Sr-Nd isotopic constraints indicating an enriched mantle source for late Cretaceous to early Tertiary volcanism, Central Anatolia, Turkey. International Geology Review, v.46/ 11, p.1022-1041

Rosing, M.T., Frei, R. (2004) U-rich Archean sea floor sediments from Greenland – indications of >3700 Ma oxygenic photosynthesis. Earth and Planetary Science Letters  v. 217, p. 237-244. Rosing and Frei - EPSL 2004-1.pdf

Meibom, A., Frei, R., and Sleep, N.H. (2004) Osmium isotopic compositions of Os-rich platinum group element alloys from the Klamath and Siskiyou Mountains, USA. Journal of Geophysical Research, v.109, B02203. Meibom et al.-JGR-2004-1.pdf

Frei, R., Polat, A., and Meibom, A. (2004) The Hadean upper mantle conundrum: Evidence for source depletion and enrichment form Sm-Nd, Re-Os, and Pb isotopic compositions in 3.71 Gy boninite-like metabasalts from the Isua Supracrustal Belt, Greenland. Geochimica et Cosmochimica Acta, v. 68, p. 1645-1660. Frei et al.-GCA-2004-1.pdf

Peng B. and Frei R. (2004) Nd-Sr-Pb isotopic constraints on metal and fluid sources in W-Sb-Au mineralization at Woxi and Liaojiaping (Western Hunan, China). Mineralium Deposita, v. 39, p. 313-327.

Andersen, T., Frei, R., Sørensen, H. and Westphal, N. (2004) The occurrence of porphyritic syenite at Lake Mykle, the Oslo rift – a possible derivate of larvikite. Norsk Geologiske Undersøkelse Bulletin, v. 442, p. 23-28.

Kent, A.J.R., Stolper, E.M., Francis, D., Woodland, J., Frei, R. , and Eiler, J. (2004) Mantle heterogeneity during the formation of the North Atlantic Igneous Province: Constraints from trace element and Sr-Nd-Os-O isotope systematics of Baffin Island picrites. Geochemistry Geophysics Geosystems, v.5/11, Q11004.

Mueller, A.G., Nemchin, A.A., and Frei, R. (2004) The Nevoria gold skarn deposit, Southern Cross greenstone belt, Western Australia: II. Pressure-temperature-time path and relationship to postorogenic granites. Economic Geology, v.99, p. 453-478.

Stendal. H., Frei, R., Muhongo, S., Rasmussen, T.M., Mnali, S., Petro, F and Temu, E.B. (2004) Lead isotopic results of the Mpanda Mineral Field mineralizations (SW Tanzania). Journal of African Earth Sciences, v.38, p. 437-447.

2003

Meibom, A., Anderson, D.L., Sleep, N.H., Frei, R., Chamberlain, C.P., Hren, M.T., and Wooden, J.L. (2003). Osmium and helium isotopic evidence against the standard stratification model of Earth’s mantle. Earth and Planetary Science Letters, v. 208, p. 197-204. Meibom et al.-EPSL-2003-1.pdf

Shotyk, W., Goodsite, M.E., Roos-Barraclough, F., Frei, R., Heinemeier, J., Asmund, G., Lohse, C., and Hansen, T.S. (2003) Anthropogenic contributions to atmospheric Hg, Pb and As deposition recorded by peat cores form southern Greenland and Denmark dated using the 14C “bomb pulse curve”. Geochimica et Cosmochimica Acta , v. 67, p.3991-4011. Shotyk  et al.-GCA-2002-1.pdf

Larsen, L.M., Pedersen, A.K., Sundvoll, B., and Frei, R. (2003) Alkali picrites formed by melting of old metasomatised lithospheric mantle: Manîtdlat Member, Vaigat Formation, Palaeocene of West Greenland. Journal of Petrology , v. 44, p. 3-38. Larsen et al.-J.Petrol.-2003-1.pdf

Gilg, H.A., Weber, B., Kasbohm, J., and Frei, R . (2003) Isotope geochemistry and origin of illite-smectite and kaolinite from the Seilitz and Kemmlitz kaolin deposits, Germany. Clay Minerals , v. 38, p. 95-112. Gilg et al.-Clay Minerals-2003.pdf

Frei, R ., and Kastbjerg Jensen, B. (2003) Re-Os, Sm-Nd isotope- and REE systematics on komatiites and pilow basalts from the Earth’s oldest oceanic crustal fragments (Isua Supracrustal Belt, W Greenland). Chemical Geology, v. 196, p.163-191. Frei and Jensen-Chem.Geol.-2003.pdf

Brenker, F.E., Meibom, A., and Frei, R. (2003) On the formation of peridotite-derived Os-rich PGE allays. American Mineralogist, v. 88, p. 1731-1740. Brenker et al.-Am.Mineral.-2003-1.pdf

2002

Frei, R. and Frei, K.M. (2002) A multi-isotopic and trace element investigation of the Cretaceous-Tertiary boundary layer at Stevns Klint, Denmark – inferences for the origin and nature of siderophile and lithophile element geochemical anomalies. Earth and Planetary Science Letters, v. 203, p. 691-708. Frei and Frei-EPSL-2002-1.pdf

Bernth, U., Brousse, R., Frei, R ., and Sørensen, H. (2002) The origin of phonolites and trachytes from the Col de Guéry area, le Mont-Dore, Massif Central, France. The Royal Danish Academy of Sciences and Letters, Matematisk-fysiske Meddelelser, v.50, 61 p. 

Barfod, G.H., Albarède, F., Knoll, A.A., Shuhai, X., Trelouk, P., Frei, R., and Baker, J.A. (2002) The age of the earliest animal fossils. Earth and Planetary Science Letters , v.201, p. 203-212. Barfod et al.-EPSL-2002.pdf

Meibom, A., Sleep, N.H., Chamberlain, C.P., Coleman, R.G., Frei, R ., Hren, M., Wooden, J.L., 2002. Re-Os isotopic evidence for long-lived heterogeneity and equilibration processes in the Earth’s upper mantle. Nature, v. 419, p. 705-708. Meibom et al.-Nature-2002-1.pdf

Frei, R., Rosing, M.T., Waight, T.E. and Ulfbeck, D.G. (2002) Hydrothermal – metasomatic and tectono-metamorphic processes in the Isua Supracrustal Belt (West Greenland): a multi-isotopic investigation of their effects on the Earth’s oldest oceanic crustal sequence. Geochimica et Cosmochimica Acta , v. 66 p. 467-486 Frei et al.-GCA-2002-1.pdf

Meibom, A., and Frei, R. (2002) Evidence for an ancient, highly radiogenic osmium isotopic reservoir in Earth. Science, v. 296, p. 516-518. Meibom and Frei-Science-2002.pdf

Rollinson, H., Appel, P., and Frei, R. (2002) A metamorphosed, early Archean chromitite from West Greenland: implications for the genesis of Archean anothositic chromitites. Journal of Petrology, v. 43, p. 2143-2170. Rollinson et al.-J.Petrol.-2002-1.pdf

Roberts, H., Dahl, P., Kelly, S., and Frei, R. (2002) New 207Pb-206Pb and 40 Ar-39Ar ages from SW Montana, USA: constraints on the Proterozoic and Archean tectonic and depositional history of the Wyoming Province. Precambrian Research, v. 117, p. 119-143. Roberts et al. - Precambrian Research 2002.pdf

2001

Blichert-Toft, J. and Frei, R. (2001) Complex Sm-Nd and Lu-Hf isotope systematics of metamorphic garnets from the Isua Supracrustal Belt, West Greenland. Geochimica et Cosmochimica Acta., v. 65, p. 3177-3187.  GCA2001-1.pdf

Frei, R., and Rosing, M.T. (2001). The least radiogenic terrestrial leads; implications for the early Archean crustal evolution and hydrothermal-metasomatic processes in the Isua Supracrustal Belt (West Greenland). Chemical Geology, v. 181, p. 47-66. Chem.Geol.2001-1.pdf

Kreissig, K., Holzer, L., Frei, R., Villa, I.M., Kramers, J.D., Kröner, A., Smit, C.A. and van Reenen, D.D. (2001). Geochronology of the Hout River Shear Zone and the metamorphism in the Southern Marginal Zone of the Limpopo Belt, Southern Africa.
Precambrian Research, v. 109, p. 145-174.

Hanghøj, K., Kelemen, P., Bernstein, St., Blusztajn, J., and Frei, R. (2001) Osmium isotopes in the Wiedemann Fjord mantle xenoliths: A unique record of cratonic mantle formation by melt depletion in the Archaean. G3, v.2.

Stendal, H., Frei, R., Hamilton, M.A., and Mueller, W.U. (2001) The Palaeoproterozoic Kangerluluk gold-copper mineralization (Southeast Greenland); Pb and Nd isotopic constraints on its timing and genesis. Mineralium Deposita, v.36, p.177-188.

Shotyk, W., Weiss, D., Kramers, J.D., Frei, R., Cheburkin, A.K., Gloor, M., and Reese, S., (2001) Geochemistry of the peat bog at Étang de la Gruyère, Jura Mountains, Switzerland, and its record of atmospheric Pb and lithogenic trace metals (Sc, ti, Y, Zr, and REE) since 12370 14C yr BP. Geochimica et Cosmochimica Acta, v. 65, p. 2337-2360. GCA2001-2.pdf

Whitehouse, M., Nägler, T.F., Moorbath, S., Kramers, J.D., Kamber, B.S., and Frei, R. (2001) Priscoan (4.00-4.03 Ga) orthogneisses from northwestern Canada - by S.A. Bowring and I.S. Williams (2000): discussion. Contributions to Mineralogy and Petrology, v. 141, p. 248-250.

Albarède, F., Blichert-Toft, J., Frei, R., and Rosing, M. (2001) Response to “Comment on “The Nd and Hf isotopic evolution of the mantle through the Archean. Results from the Isua supracrustals, West Greenland, and from the Birimian terranes of West Africa” by Blichert-Toft et al. (1999). Geochimica et Cosmochimica Acta, 65, p. 2023-2025.

Przybylowicz, W.J., Mesjasz-Pryzybylowicz, J., Pineda, C.A., Churms, C.L., Ryan, C.G., Prozesky, V.M., Frei, R., Slabbert, J.P., Padayachee, J., and Reimold, W.U. (2001). Elemental mapping using proton-induced X-rays. X-Ray Spectrometry, v.30, p.´156-163

2000

Stendal, H. and Frei, R. (2000), Gold occurrences and lead isotopes in Ketilidian Mobile Belt, South Greenland. Transaction Institution of Mining and Metallurgy (Section B), v. 109, B6-13.

Boni, M., Di Maio, G., Frei, R., and Villa, I.M. (2000), Lead isotopic evidence for a mixed provenance for Roman water pipes from Pompeii. Archaeometry, v. 42, p. 201-208.

1999

Blichert-Toft, J., Albarède, F., Rosing, M.T., Frei, R., and Bridgwater, D., 1999, The Nd and Hf isotopic evolution of the mantle through the Archean. Results form the Isua supracrustals, West Greenland, and from the Birimian terranes of West Africa. Geochimica et Cosmochimica Acta, v.63, p. 3901-3914. GCA1999-1.pdf

Bird, J.M., Meibom, A., Frei, R., and Nägler, Th.F., 1999, Osmium and lead isotopes of rare OsIrRu minerals: A core-mantle boundary derivation? Earth and Planetary Science Letters. v.170, p. 83-92. EPSL1999-1.pdf

Frei, R., Bridwater, D., and Rosing, M., 1999, Controversial Pb-Pb and Sm-Nd isotope systematics in the Archean Isua (West Greenland) oxide iron formation; preservation of primary signatures versus secondary disturbances. Geochimica et Cosmochimica Acta, v. 63 (3/4), p.473-488. GCA1999-2.pdf

Buick, I.S., Frei, R., and Cartwright, I., 1999., The timing of high-temperature retrogression in the Reynolds Range, central Australia: constraints from single mineral Pb-Pb dating. Contributions to Mineralogy and Petrology, v.135 (2/3), p. 244-254.

Frei, R., Blenkinsop, T.G., and Schönberg, R., 1999, Geochronology of the late-Archean Razi and Chilimanzi suites of granites in Zimbabwe; implications for the late Archean tectonics of the Limpopo belt and Zimbabwe craton. South African Journal of Geology, v.102, p. 55-63.

1998

Shotyk, W, Weiss, D., Appleby, P.G., Cheburkin, A.K, Frei, R., Gloor, M., Kramers, J.D., Reese, S., and von der Knaap, W.O., 1998., A complete history of atmospheric lead deposition from 12,370 14C yr BP to the present recorded in a peat bog profile, Jura Mountains, Switzerland. Science., v. 281/5389, p. 1635-1640.

Frei, R., Nägler, Th.F., Schönberg, R., and Kramers, J.D, 1998, Re-Os, Sm-Nd, U-Pb and stepwise Pb leaching isotope systematics in shear-zone hosted gold mineralization; genetic tracing and age constraints of crustal hydrothermal activity. Geochimica et Cosmochimica Acta, v. 62, p.1925-1936. GCA1998-1.pdf

Mahoney, J.J., Frei, R., Tejada, M.L.G., Mo, X.X., Leat, P.T., and Nägler, T.F., 1998, Tracing the Indian Ocean Mantle domain through time: isotopic results from old West Indian, East Tethyan, and South Pacific seafloor. Journal of Petrology, v.39/7, p. 1285-1306.

Buchholz, P., Herzig, P., Friedrich, G., and Frei, R., 1998, Granite-hosted gold mineralization in the Midlands greenstone belt: a new type of low-grade large scale gold deposit in Zimbabwe. Mineralium Deposita, v.33, p.437-460.

Frei, R., Nägler, Th.F., Schönberg, R., and Kramers, J.D., 1998, Behaviour of Re-Os, Sm-Nd, and U-Pb systematics in hydrothermal ores. WRI-9, International Congress on Water-Rock Interaction, 30.3. - 3.4.1998, Taupo, New Zealand. In: Arehart, G.B. and Hulston, J.R. (eds), Water-Rock Interaction, Balkema/Rotterdam/Brookfield, p.541-544.

Kamber, B.S., Frei, R., Gibb, A.J., and O’Nions, R.K., 1998, Pitfalls and new approaches in granulite chronometry - an example from the Limpopo Belt, Zimbabwe. Precambrian Research, v.91(3/4), p. 269-285.

Holzer, L, Frei, R., Barton jr., J.M., and Kramers, J.D., 1998., Unraveling the record of successive high grade events in the Central Zone of the Limpopo Belt using Pb single phase dating of metamorphic minerals. Precambrian Research, v.87, p.87-115.

Dahl, P.S., and Frei, R., 1998., Step-leach Pb-Pb dating of inclusion-bearing garnet and staurolite; with implications for Early Proterozoic tectonism in the Black Hills collisional orogen, South Dakota, United States. Geology, v.26/2, p. 111-114.

1997

Frei, R., Prozesky, V.M., and Przybylowicz, W., 1997, Studies of progressive leaching in single mineral Pb/Pb dating. Nuclear Microprobe Technology and Applications. Nuclear Instruments and Methods in Physics Research, B 130, p.676-681.

Nägler, Th.F., Kramers, J.D., Kamber, B.S., Frei, R., and Prendergast, M.D.A., 1997, Growth of subcontinental lithospheric mantle beneath Zimbabwe started at ~3.8 Ga: A Re-Os study on chromites. Geology, v 25/11, p 983-986.

Blenkinsop, T.G., and Frei, R., 1997, Archean and Proterozoic mineralization and tectonics at Renco Mine (Northern Marginal Zone, Limpopo Belt, Zimbabwe) - a reply. Economic Geology, v.92, p. 747-748.

Frei, R., and Pettke, T., 1997, Mono-sample Pb-Pb dating of pyrrhotite and tourmaline: Archean vs. Proterozoic gold mineralization in Zimbabwe. A Reply: Geology, v. 27, p.670-671

Gilg, H.A. and Frei, R., 1997, Isotope dating of residual kaolin deposits in Europe (Tirschenreuth, Germany and St. Yrieix, France).In: Energy and Mineral Resources for the 21st Century, Geology of Mineral Deposits, Mineral Economics (P. Rongfu, editor) Proceedings of the 30th International Geological Congress, Beijing, P. R. China, 4-14. Aug. 1996. Vol. 9. VSP, International Science Publisher, Zeist, Netherlands, p. 123-133.

Gilg, H.A., Haus, R. and Frei, R. 1997 A new illite deposit near Le-Puy-en-Velay (France) - Genesis and usage for waste encapsulation. In: H. Papunen (Ed.) Mineral Deposits: Research and exploration -where do they meet ? Proceedings of 4th Biennial SGA Meeting, 11-13 Aug. 1997, Turku, Finland, Balkema: Rotterdam, p. 717-720. (extended abstract).

Nägler, Th.F., and Frei, R., 1997, ‘Plug in plug’ Os distillation. Schweizerische Mineralogische Petrographische Mitteilungen, v.77, p.123-127

Schaller, M., Steiner, O., Studer, I., Frei, R., and Kramers, J.D., 1997, Pb stepwise leaching (PbSL) dating of garnet - addressing the inclusion problem. Schweizerische Mineralogische Petrographische Mitteilungen, v.77, p.113-121

Nägler, Th.F., and Frei, R., 1997, Mantle-derived K-feldspar granites in oceanic crust (Masirah ophiolite, Sultanate of Oman): Chemical Geology, v.138, p.119-126.

Pettke, T., Frei, R., Kramers, J.D., and Villa, I.M., 1997., Isotope systematics in vein gold from Brusson, Val d’Ayas (NW Italy). 2: (U+Th)/He and K/Ar in native Au and its fluid inclusions. Chemical Geology, v.135; p.173-187

Cheburkin, A.K., Frei, R., and Shotyk, W., 1997, An energy-dispersive Miniprobe Multielement analyzer (EMMA) for direct analysis of trace elements and chemical age dating of single mineral grains: Chemical Geology, v.135, p. 75-87.

Frei, R., Villa, I.M., Nägler, Th.F., Kramers, J.D., Przybylowicz, W.J., Prozesky, V.M., Hofmann, B.A., and Kamber, B.S., 1997, Single mineral dating by the Pb-Pb step-leaching method, assessing the mechanism. Geochimica et Cosmochimica Acta, v.61, p. 393-414. GCA1997-1.pdf

1996

Blenkinsop, T.G., and Frei, R., 1996, Archean and Proterozoic mineralization and tectonics at Renco Mine (Northern Marginal Zone, Limpopo Belt, Zimbabwe). Economic Geology, v.91, p. 1225-1238

Gilg, H.A., and Frei, R. (1996), Isotope dating of residual kaolin deposits in Europe (Tirschenreuth, Germany and St. Yrieix, France). Proceedings of the 30th International Geological Congress, Beijing, P.R. China, 4-14. Aug. 1996. VSP, International Science Publisher, Zeist, Netherlands, 10p.

Dhar, S., Frei, R., Kramers, J.D., Nägler, Th.F., and Kochhar, N., 1996, Sr, Pb and Nd isotope studies and their bearing on the petrogenesis of the Jalor and Siwana complexes, Rajasthan, India. A reply. Journal of the Geological Society of India, v. 49/4, p. 466-469.

Frei, R., 1996, The extent of inter-mineral isotope equilibrium: a systematic bulk U-Pb step leaching (PbSL) isotope study of individual minerals from the Tertiary granite of Jerissos (northern Greece). European Journal of Mineralogy, v.8, p. 1175-1189.

Frei, R., and Pettke, T., 1996, Mono-sample Pb-Pb dating of pyrrhotite and tourmaline: Archean vs. Proterozoic gold mineralization in Zimbabwe: Geology, v.24, p. 823-826

Vinyu. M.L., Frei, R., and Jelsma, H.A.,1996, Timing between granitoid emplacement and associated gold mineralization: examples from the ca. 2.7 Ga Harare-Shamva Greenstone Belt, Northern Zimbabwe: Canadian Journal of Earth Sciences, v.33/7, p. 981-992.

Dhar, S., Frei, R., Kramers, J.D., Nägler, Th.F., and Kochhar, N., 1996, Sr, Pb and Nd isotope studies and their bearing on the petrogenesis of the Jalor and Siwana complexes, Rajasthan, India. Journal of the Geological Society of India, v. 48/2, p. 151-160.

Frei, R., Nägler, Th.F., and Meisel, T., 1996, Efficient N-TIMS Re-isotope measurements on outgassed Ta filaments: very low filament blanks determined by a “standard addition” approach. International Journal of Mass Spectrometry and Ion Processes, v. 153, L7-L10.

Hofmann, B.A., and Frei, R., 1996, Age constraints of reduction spot formation from Permian red bed sediments, northern Switzerland, inferred from U-Th-Pb systematics: Schweizerische Mineralogisch-Petrographische Mitteilungen, v.76, 235-244.

Pettke, T., and Frei, R., 1996, Isotope systematics in vein gold from Brusson, Val d’Ayaz (NW Italy). I: Pb/Pb evidence for a Piemonte metaophiolite Au source: Chemical Geology, v. 127, p. 11-124.

Frei, R., 1996, Sulfur in bulk rock and igneous apatite; tracing mineralized and barren trends in intrusions. Schweizerische Mineralogische und Petrographische Mitteilungen, v. 76, p.  57-73.


back to first page


Available Master / Ph.D. Projects

Master projects that I propose:

1.    Application of stable Cr systematics to Neoproterozoic-Cambrian profiles (Uruguay, Argentina, Canada, Namibia, Wyoming etc.)

2.    Ce isotopes in the oceanic sedimentary environment - is there natural isotopic variation?

3.    Cr isotopic systeamtics in weathering profiles and palaeo-soils

4.    Isotope systematics of Late Archean BIFs from the Seminoe Mtn. and Atlantic City (South Pass Greenstone Belt) areas, Wyoming.

 


Ph.D. project ideas:
1. REE and Re-Os systematics of ancient komatiites and komatiic basalts: Was the mantle chondritic throughout the Archean?

2. REE and PGE systematics of BIFs through time: What can we say about the Archean hydrosphere and atmosphere?

3. Cr isotope systematics of ancient sediments from the Isua Greenstone Belt, W. Greenland.

4. Cr isotope systematics in Neoproterozoic sequences.


If you are interested in starting a Ph.D. study, do not hesitate to contact me (e-mail: robertf@geol.ku.dk ). I welcome your own project ideas, however the topic(s) should match my own research frame and should contribute essentially to the general interests lined out above. 


Projects that will be available from the beginning of 2008, funded by FNU

Projects in Western Greenland, Botswana, South Africa, Southern America South Dakota and Wyoming (USA): comparative studies of 4 Archean blocks. The projects will involve field work (mapping) and sampling in collaboration with GEUS, the University of Gabarone, the Geological Survey of Botswana, the Geological Survey of Wyoming, the South Dakota School of Mines, and Kent State University (Ohio, USA)




Latest fieldwork in 2004 (some pictures)


Botswana: Excursion team ; 2.6 Ga old Banded Iron Fm. ; Mupanda Gold Fields - drill cores
Black Hills (South Dakota, USA): Field team ; Cordierite schist ; Homestake Mine (Lead) ; Jack Redden ; Discussing... ; Karin and Sarah

back to top page
back to the DCIG's homepage

last up-dated: January 8, 2008; RF