English Intern
Chair of Geodynamics and Geomaterial Research

Rohstoffe

Laufende Projekte zum Thema Rohstoffe

  • Prof. Dr. Hartwig E. Frimmel
  • Dr. Alexander Kawohl
  • BSc hons., P.Geo. Wesley E. Whymark (Inventus Mining Corp., Toronto)
  • BSc, P.Geo. Andrejs Bite (Bite Geological Ltd., Sudbury)

Project duration: 2016 - 2022

Funding (2019 - 2022): German Research Foundation (DFG) Project number 418960271

Funding (2016 - 2018): Canadian Continental Exploration Corp., Toronto

Summary:

This project attempts to explain the ultimate geological cause of one of the largest, hitherto unexplained, magnetic anomalies in North America, the Temagami geophysical anomaly in Ontario, Canada. The anomaly is of outstanding scientific and economic interest because it is directly adjacent to the 1.85 Ga Sudbury Complex - the second largest impact structure on Earth and one of the world’s richest mining districts thanks to widespread Ni-Cu-PGE-sulfide mineralization. The Temagami Anomaly mirrors the magnetic anomaly caused by the Sudbury Complex in terms of shape, size and intensity. Lack of outcrops and, until recently, of bore holes, prevented a proper geological understanding, and whatever genetic link with the Sudbury Complex has remained pure speculation. Preliminary petrological studies by the applicant and the anticipated project scientist (PhD student) on the first deep drill hole sunk into the centre of the Temagami Anomaly revealed the presence of dioritic rocks at 2 km depth, which bear similarities with offset dykes in and around the Sudbury Complex. This raises the possibility of a genetic link with the Sudbury impact event, which if proved correct, would open up an entirely new perspective on our understanding of the Sudbury Complex and its exploration potential. Thus, the principal aim of this project is to test for such a genetic link and to provide a geological explanation for the geophysical anomaly by comparing new data on the petrology, alteration history, geochemistry, isotopic composition and geochronology to be acquired from drill core and surface samples from the area of the Temagami Anomaly with available data on the Sudbury Complex and potentially equivalent rocks in the wider region. This will include layered mafic and ultramafic intrusions, mafic dyke swarms, carbonatite stocks, and sedimentary iron formations, all of which occur in the area, bear significant economic potential, and could be possible candidates for the observed magnetic anomaly. Our preliminary observations revealed also widespread hydrothermal alteration and brecciation, whose origin and bearing on the magnetic anomaly is unclear. Thus, a further goal of the project will be to characterize this alteration and to establish its significance in terms of the cause of the Temagami Anomaly, the genesis of the Sudbury structure and the metallogeny of the area.

Publications:

Kawohl, A., Frimmel, H.E., Whymark, W.E., Millonig, L.J. and Gerdes, A., 2022. Geology, geochemistry, and apatite/titanite U-Pb geochronology of ca. 1.88 Ga alkaline ultrabasic dykes in the Southern Province near Sudbury, Ontario. Canadian Journal of Earth Sciences, in press.

Kawohl, A., Whymark, W.E., Bite, A. and Frimmel, H.E., 2020. High-Grade Magmatic Platinum Group Element-Cu(-Ni) Sulfide Mineralization Associated with the Rathbun Offset Dike of the Sudbury Igneous Complex (Ontario, Canada). Economic Geology, 115, pp.505-525.

Kawohl, A., Frimmel, H.E., Whymark, W. and Bite, A., 2019. Rathbun Lake revisited: a magmatic-hydrothermal Pd-Pt-Cu occurrence possibly related to the Sudbury impact. Proceedings of the 15th biennial SGA meeting, Glasgow,  Volume 2, pp. 605-608.

Kawohl, A., Frimmel, H.E., Bite, A., Whymark, W. and Debaille, V., 2019. Very distant Sudbury impact dykes revealed by drilling the Temagami geophysical anomaly. Precambrian Research, 324, pp.220-235.

Kawohl, A., Frimmel, H.E., Bite, A. and Whymark, W., 2017. What’s inside the Temagami geophysical anomaly, Sudbury district, Ontario?. Proceedings of the 14th biennial SGA meeting, Quebec, Volume 4, pp.1543-1546.

Project duration: since 2017

Supported by the Faculty of Philosophy, University of Wuerzburg 

Summary: 

The determination of the so called “no-traditional” stable isotopes 63Cu and 65Cu became a useful and widely used tool in the field of ore geology in the last years. Nevertheless, the influence of metamorphism on the Cu-isotope ratio is still unclear. In this study, we compare the 65Cu/63Cu isotope ratios of several sedimentary-exhalative deposits from all over the world to their respective metamorphic grade to determine the effects of this overprint. To eliminate interference with other factors controlling the Cu-isotope ratios we concentrate our research on deposits, which reveal a maximum of (primary) similarity except from their metamorphic grade. 

Publications:

Höhn, S., Frimmel, H.E., Debaille, V., 2019. Pre-metamorphic oxidation of the Broken Hill deposit at Aggeneys (South Africa) revealed by Cu isotopes. Proceedings of the 15th Biennial SGA meeting, Glasgow, Volume 3, pp. 1212-1215.

Höhn, S., Frimmel, H.E., Debaille, V., Pasava, J., Kuulmann, L., Debouge, W., 2017. The case for metamorphic base metal mineralization: pyrite chemical, Cu and S isotope data from the Cu-Zn deposit at Kupferberg in Bavaria, Germany. Mineralium Deposita 52:1145–1156.

Project duration: since 2016

Supported by the German Research Foundation (DFG) and the Indian National Science Academy (INSA) 

Summary:

The goal of this project is a multidisciplinary geological analysis of the Bababudan Group in the western Dharwar Craton in southern India. The Bababudan Group is of particular interest because it contains at its base conglomerates that have been compared with the highly auriferous conglomerates of the Witwatersrand Basin in South Africa. They occur in a similar geological and stratigraphic position and are of presumably similar Mesoarchaean age. The Witwatersrand deposits are the largest known gold anomaly in the Earth’s crust and have been of enormous economic significance. The rocks of the Bababudan Group are, in comparison, only very poorly studied, which has inhibited a meaningful assessment of their geological history as well as their economic potential. To change this situation, a characterisation is planned of the sedimentology, petrology, mineralogy, geochemistry and geochronology of the Bababudan Group, with special emphasis on the basal conglomerate unit. 

Project duration: since 2015

Funded by Inventus Mining Corp.

Summary:

The 2.45 to 2.2 Ga Huronian Basin in Ontario, Canada, has been thought to contain many similarities with the famous Witwatersrand goldfields in South Africa. Recent discoveries suggest the Huronian Basin may contain Witwatersrand-type gold deposits. The gold mineralization has been discovered within separate conglomeratic stratigraphy of both the Mississagi and Matinenda formations. These discoveries have developed into what is now known as the Pardo project in Pardo Township 65 km northeast of the famous Sudbury mining camp. The basal Mississagi cobble to boulder conglomerates can contain values up to 542 g/t Au. The Pardo project is located in the eastern portion of the Huronian Basin known as the Southern Cobalt Embayment. The western portion of the basin, which is most analogous to the Witwatersrand, is historically known for its uraniferous quartz- pebble conglomerates of the Matinenda Formation at Elliot Lake. This investigation plans to examine and compare the mineralogy, chemistry and distribution of gold in both the Mississagi and Matinenda Formations. This will provide insight as to the reasons for gold occurring in the Matinenda Formation at Pardo, which is not seen elsewhere in the basin. The study will also examine the Mississagi sedimentary environment and study its provenance, by examining a comprehensive selection of clasts to determine their source(s) and whether they contributed gold to the Mississagi Formation. Detailed lithofacies analysis of both diamond drill core and outcrop exposures will provide valuable information regarding the channelized nature of the conglomerates as well as to provide a framework for gold resource analysis.

Publications:

Whymark, W.E., Frimmel, H.E., 2018. Regional gold-enrichment of conglomerates in Paleoproterozoic supergroups formed during the 2.45 Ga rifting of Kenorland. Ore Geology Reviews, 101, 985-996.

Project duration: since 2012

Partly funded by the German Research Foundation (DFG), partly by mining companies

Summary:

The Moeda and Jacobina deposits in northeastern Brazil are the economically most important known conglomerate-hosted gold deposits in South America. Their genesis has often been compared with that of the world’s largest known gold anomaly in the Mesoarchaean Witwatersrand Basin in South Africa. In contrast to the latter, very few studies have been carried out to date on the South American examples with partly conflicting results. Uncertainties existed with regard to metallogenesis and age as well as on the significance of post-depositional alteration. This project aims at overcoming these obstacles in our understanding.  Detailed field mapping of underground exposures of the auriferous Moeda Formation conglomerate and statistical analysis of the gold distribution therein revealed a strong sedimentological control on ore grade, with most of the gold being concentrated on top of an old erosion surface. Combined U-Pb and Lu-Hf isotope data obtained on detrital zircon grains from these deposits constrained the sedimentation age to 2.68 Ga and gave important information about possible source areas, indicating major reworking of older crust in the hinterland of the Moeda Formation’s depositional basin. Rutile grain analysis yielded atypically high REE and Th concentrations. In combination with U-Pb isotopic data, these data revealed a major metamorphic overprint combined with different stages/intensities of fluid-rock interactions at 2.25 Ga. Gold morphological studies revealed the presence of both hydrothermal gold and detrital gold micronuggets, which corroborate the notion of a modified palaeoplacer genesis. Mineralogical evidence from gold–tourmaline intergrowths on authigenic pyrite indicates that the transporting fluid was boron-rich but poor in aqueous sulfide species, at least at Moeda. In contrast to Moeda, the Jacobina deposits experienced a higher degree of metamorphism and hydrothermal overprint, being located near a major thrust plane. Nevertheless, primary mineralogical and mineral chemical features remained preserved in places. Systematic difference in gold composition between different conglomerate units (reefs) and undoubtedly hydrothermal gold in cross-cutting veins, shear zones and intrusive bodies, attest to original placer deposits with variable provenance and subsequent syn-orogenic reworking of the ore.

Publications:

Koglin, N., Zeh, A., Cabral, A.R., Seabra Gomes Jr., A.A., Corrêa Neto, A.V., Brunetto, W.J., Galbiatti, H. (2014): Depositional age and sediment source of the auriferous Moeda Formation, Quadrilátero 
Ferrífero of Minas Gerais, Brazil: New constraints from U–Pb–Hf isotopes in zircon and xenotime. Precambrian Research 255, 96-108.

Cabral, A.R., Koglin, N. (2012): Hydrothermal fluid source constrained by Co/Ni ratios in coexisting arsenopyrite and tourmaline: the auriferous lode of Passagem, Quadrilátero Ferrífero of Minas Gerais, Brazil. Mineralogy and Petrology 104, 137-145.

Cabral, A.R., Zeh, A., Koglin, N., Seabra Gomes Jr., A.A., Viana, D.J., Lehmann, B. (2012): Dating the Itabira iron formation, Quadrilátero Ferrífero of Minas Gerais, Brazil, at 2.65 Ga: Depositional U–Pb age of zircon from a metavolcanic layer. Precambrian Research 204-205, 40-45.

Koglin, N., Cabral, A.R., Brunetto, W.J., Vymazalová, A. (2012a): Gold–tourmaline assemblage in a Witwatersrand-like gold deposit, Ouro Fino, Quadrilátero Ferrífero of Minas Gerais, Brazil: the composition of gold and metallogenic implications. Neues Jahrbuch für Mineralogie, Abhandlungen 189/3, 263-273.

Koglin, N., Cabral, A.R., Brunetto, W.J., Brätz, H. (2012b): Gold and uranium contents in gypsum formed from percolating ground water in a Witwatersrand-like gold deposit, Ouro Fino, Minas Gerais, Brazil: LA– ICPMS data. Neues Jahrbuch für Mineralogie, Abhandlungen 189/2, 189-195. 

Project duration: since 2012

Supported by the South African National Research Foundation (NRF) and mining companies 

Summary:

Gold is concentrated in the Earth’s crust in a multitude of different deposit types. These include orthomagmatic deposits, a great variety of hydrothermal deposits with and without magmatic affiliation, as well as syn-sedimentary deposits, such as placers. This wide range in deposit types reflects the multitude of physical and chemical processes that can lead to enrichment in gold from typical crustal background values of a few ppb to economic ore grade values of several ppm.

The temporal variation in gold endowment with regard to different deposit types throughout Earth’s history reveals that certain time periods were more suitable for specific styles of gold mineralization than others. From an economic point of view, there are only four deposit types that play a superordinate role. Of all the gold that has been mined so far and that is known to exist as reserves and suspected as resources, about 30 % occurs (occurred) as orogenic-type gold, further 30 % as conglomerate-hosted Witwatersrand-type, 16 % was (is) in porphyry (Cu-)Au and 12 % in epithermal deposits. All other deposit types together account for not more than 12 %, with the Carlin-type being most noteworthy. Focusing on the most important deposit types, a good correlation between the secular distribution of gold in mesothermal, typically shear zone-hosted quartz veins and intensity of orogenic activity has long been recognized [1], hence the term “orogenic-type”. Similarly, the strong temporal bias of porphyry-hosted and epithermal gold towards Cenozoic ages has long been explained by low preservation potential of such shallow crustal phenomena in older units. The dominance of orogenic and porphyry/epithermal gold highlights the significance of gold recycling by means of subduction, collision and orogenic crustal growth. Notwithstanding the fact that for some deposits, e.g. the Palaeozoic Muruntau deposit, a juvenile, mantle-derived addition of gold to the crust seems indicated [2], most of the post-2.8 Ga gold is suggested to have been recycled gold that had entered the crust in the course of a singular gold mega-event at around 2.9 Ga [3]. 

Although most of the continental crust must have formed prior to 3.0 Ga [4], no major orogenic gold deposits are known from pre-Neoarchaean times, suggesting a lack of crustal gold available for tectonic recycling at those early times. This changed with the postulated 2.9 Ga gold mega-event, which led to the formation of Witwatersrand-type deposits, preferentially in Mesoarchaean fluvial conglomerates, first possibly by microbial fixation of gold that had been dissolved in Mesoarchaean rivers and seawater, followed by the sedimentary reworking of the thus formed gold-rich microbial mats into placers [3]. In spite of the very low preservation potential of these surface deposits, the largest proportion of known gold was, or still is, bound to these Mesoarchaean conglomerates. Much of the younger gold deposits, irrespective of their genesis, is likely to be derived from gold originally concentrated into the crusts by the 2.9 Ga mega-event. This is supported by the extraordinary chemistry of the 2.9 Ga gold, which contains orders of magnitude more Os than younger gold. 

Publications:

Nwaila, G.T., Frimmel, H.E., 2019. Highly siderophile elements in Archaean and Palaeoproterozoic marine shales of the Kaapvaal Craton, South Africa. Mineralogy and Petrology, 113(3), 307-327.

Frimmel, H.E., 2019. The Witwatersrand Basin and Its Gold Deposits. In The Archaean Geology of the Kaapvaal Craton, Southern Africa (pp. 255-275). Springer, Cham.

Frimmel, H.E., 2018. Episodic concentration of gold to ore grade through Earth's history. Earth-Science Reviews, 180, 148-158.

Frimmel, H.E., Hennigh, Q., 2015, First whiffs of atmospheric oxygen triggered onset of crustal gold cycle. Mineralium Deposita, 50, 5-23.

Frimmel, H.E., 2017, Gold through time and space. In Mercier-Langevin, P., Dube, B., Bardoux, M., Ross, P.-S., Dion, C. (eds.), Mineral Resources to Discover, Proc. 14th SGA Biennial Meeting, 20-23 August 2017, Quebec City, Society for Geology Applied to Mineral Deposits, vol. 1, 3-6.

Nwaila, G., Frimmel, H.E., 2017, Geochemistry of marine shales in the West Rand and Central Rand groups of the Mesoarchaean Witwatersrand Basin: implications for sedimentary gold endowment. In Mercier-Langevin, P., Dube, B., Bardoux, M., Ross, P.-S., Dion, C. (eds.), Mineral Resources to Discover, Proc. 14th SGA Biennial Meeting, 20-23 August 2017, Quebec City, Society for Geology Applied to Mineral Deposits, vol. 1, 75-78.

Frimmel, H.E., 2015, Onset of crustal gold cycle triggered by first oxygenic photosynthesis. In AndréMayer , A.-S., Cathelineau, M., Muchez, P., Pirard, E., Sindern, S. (eds.) Mineral Resources in a Sustainable World, Proc. 13th Biennial SGA Meeting, 24-27 August 2015, Nancy, Université de Lorraine, v. 1, 25-28.

Hölzing, A., Frimmel, H.E., Voland, V., Dremel, K., Zabler, S., Minter, W.E.L., 2015, The cover of Mineralium Deposita’s anniversary volume uncovered. In André-Mayer , A.-S., Cathelineau, M., Muchez, P., Pirard, E., Sindern, S. (eds.) Mineral Resources in a Sustainable World, Proc. 13th Biennial SGA Meeting, 24-27 August 2015, Nancy, Université de Lorraine, v.4, 1407-1410.

Nwaila, T.G., Frimmel, H.E., Minter, W.E.L., Beukes, N., 2015, Provenance and geochemical variations in shales of the Mesoarchaean Witwatersrand Supergroup. In André-Mayer , A.-S., Cathelineau, M., Muchez, P., Pirard, E., Sindern, S. (eds.) Mineral Resources in a Sustainable World, Proc. 13th Biennial SGA Meeting, 24-27 August 2015, Nancy, Université de Lorraine, v. 1, 169-172.

Frimmel, H. E., 2014, A giant Mesoarchean crustal gold-enrichment episode: Possible causes and consequences for exploration: Society of Economic Geologists, Special Publication, 18, 209-234.  

Abgeschlossene Projekte zum Thema Rohstoffe

Project duration: 2014 - 2017

Supported by the “Oberfrankenstiftung”, “Hanns-Seidel-Stiftung” and Schicker mining

Summary:

The objective of the project was the hitherto enigmatic genesis of Bavaria´s largest Cu-Zn deposit at Kupferberg. The application of whole-rock and mineral geochemistry, U-Pb zircon dating, Cu and S isotope analyses revealed the metamorphogenic origin of the deposit. It could be shown, that the genesis of the sulfide lenses is connected to the overthrusting of the allochthonous Münchberg metamorphic complex onto the parautochthonous volcanosedimentary rocks of the Saxothuringian Vogtland Syncline. In the ongoing of this process trace elements like Cu, Zn and Au where mobilized from sedimentary/diagenetic pyrite in the footwall. The product of this process was a metamorphogenic, metal rich fluid from which the sulfides precipitated when it reached the brittle-ductile-transition zone and started boiling. The results further indicate, that similar appearing base metal deposits all around the Münchberg metamorphic complex share the same genetic history.

Publications:

Höhn, S., Koglin, N., Klopf, L., Schüssler, U., Tragelehn, H., Frimmel, H.E., Zeh, A. and Brätz, H. (2018): Geochronology, stratigraphy and geochemistry of Cambro-Ordovician, Silurian and Devonian volcanic rocks of the Saxothuringian Zone in NE Bavaria (Germany)—new constraints for Gondwana break up and ocean–island magmatism. International Journal of Earth Sciences, 107(1), pp.359-377.

Höhn, S., Frimmel, H.E., Debaille, V., Pasava, J., Kuulmann, L., Debouge, W. (2017): Metamorphogenic base metal mineralization at the margin of a nappe complex: the example of Kupferberg, Germany.-  In: Mineral Resources to Discover, Proceedings of the 14th Biennial SGA meeting, 20-23 August 2017 (Quebec, Canada).

Höhn, S., Frimmel, H.E., Debaille, V., Pasava, J., Kuulmann, L., Debouge, W. (2017): The case for metamorphic base metal mineralization: pyrite chemical, Cu and S isotope data from the Cu-Zn deposit at Kupferberg in Bavaria, Germany. Mineralium Deposita 52: 1145– 1156.

Höhn S, Frimmel HE, Koglin N (2015) Multi-stage sulfidation at Bavaria‘s largest Cu-Zn deposit (Kupferberg/Germany).- In: André- Mayer A-S (ed) Mineral resources in a sustainable world, Proceedings of the 13th Biennial SGA meeting, 24 – 27 August 2015, Université de Lorraine (Nancy, France).  

Project duration: 2010 - 2013

Summary:

Four kaolin deposits in the Bohemian Massif were studied in order to assess the potential for the recovery of rare earth elements (REE) as by-products from the residue after extraction and refining of the raw kaolin. The behaviour of REE+Y during kaolinitization was found to be largely a function of pre-alteration mineralogy. In the examples studied, i.e. granite-derived deposits of Kriechbaum (Austria) and Božičany, and arkose-derived deposits of Kaznějov and Podbořany (all Czech Republic), the REE+Y are predominantly hosted by monazite which has remained unaffected by kaolinitization. The overall REE+Y content of the variably kaolinitized rocks is strongly dependent on their genesis. While ion-adsorption plays an only minor role in the concentration of REE+Y in the studied kaolinitized rocks, the processing and refining of the raw kaolin leads to residues that are enriched in REE+Y by a factor of up to 40. The use of a magnetic separator and a hydrocyclone in the processing of the raw material can yield REE+Y contents of as much as 0.77 wt%. Although this value compares well with the REE+Y concentration in some potentially economic REE+Y-projects elsewhere, the overall tonnage of the (REE+Y) enriched residue is by far not sufficient to consider economic extraction of REE+Y as by-product. Our results are most probably applicable also to other kaolin deposits derived from the weathering of Hercynian basement granites elsewhere (e.g. in Saxonia and Bavaria, Germany). Overall, the potential for REE+Y production as by-product from kaolin mining has to be regarded as minimal.

Publications:

Höhn, S., Frimmel, H.E., Pasava, J., 2014, The rare earth element potential of kaolin deposits in the Bohemian Massif (Czech Republic, Austria). Mineralium Deposita, 49, 967-986.

Project duration: 2010 - 2014

Summary:

Electron microprobe and laser ablation-inductively coupled plasma mass spectrometric (LA-ICPMS)analyses were carried out on individual uraninite grains from several localities worldwide, representing a variety of different U-deposit types ranging in age from Mesoarchaean to the Mesozoic. For the first time, concentration data on a comprehensive set of minor/trace elements in uraninite are presented, i.e. LA-ICPMS concentration data for Th, Si, Al, Fe, Mn, Ca, Mg, P, Ti, V, Cr, Co, Ni, Pb, Zn, As, rare earth elements (REE), Y, Zr, Nb, Mo, Ag, Ta, W, Bi, and Au. Most of these elements could be detected in significant quantities in many of the studied examples. The results obtained in this study, supplemented by previously published data on major element and REE concentrations, reveal systematic differences in uraninite composition between genetically different deposit types and also, for a given genetic type, between different locations.

Low-temperature hydrothermal uraninite is marked by U/Th >1000, whereas high-temperature metamorphic and magmatic (granitic, pegmatitic) uraninite has U/Th <100. Our new data also confirm previous observations that low-temperature, hydrothermal uraninite has low total REE contents (<1 wt%) whereas higher temperature uraninite can contain as much as several percent total REE. Genetically different uraninite types can be further identified by means of different REE fractionation patterns. Systematic differences between primary uraninite from different localities could be also noted with respect to the abundances of especially Y, V, W, Zr, Nb, Ta, and to a lesser extent Mo, P, Bi,and As. Our findings open up the possibility of using uraninite chemistry as provenance tool, both for geological applications, as exemplified in this study by the application to uraninite in the Mesoarchean Witwatersrand Basin (South Africa), as well as for forensic purposes to track down the likely source of illegally mined uraninite. Uraninite chemistry provides strong support for a palaeoplacer model for the U-mineralisation in the auriferous and uraniferous conglomerates of the Witwatersrand, in which individual uraninite particles display chemical characteristics typical of high-temperature (magmatic) uraninite and a great variation in trace element concentrations that point to a variety of (magmatic) source rocks.

Publications:

Frimmel, H.E., Schedel, S., Brätz, H., 2014, Uraninite chemistry as forensic tool for provenance analysis. Applied Geochemistry, 48, 104-121.

Depiné, M., Frimmel, H.E., Emsbo, P., Koenig, A.E., Kern, M., 2013, Trace element distribution in uraninite from Mesoarchaean Witwatersrand conglomerates (South Africa) supports placer model and magmatogenic source. Mineralium Deposita 48, 423-435.

Frimmel, H.E., Depiné, M., Emsbo, P., Koenig, A.E., Kern, M., 2013, Reply to comments by T. Oberthür on “Trace element distribution in uraninite from Mesoarchaean Witwatersrand conglomerates (South Africa) supports placer model and magmatogenic source”. Mineralium Deposita 48, 1051-1053.

Frimmel, H., Emsbo, P., Koenig, A.E, 2009, The source of Witwatersrand Gold: Evidence from uraninite chemistry. In Williams, P.J. et al (eds.) Smart Science for Exploration and Mining. Proc. 10thBiennial SGA Meeting, 17-20 August 2009, Townsville, v.1, p. 353-355

Project duration: 2009 - 2013

Supported by the German Academic Exchange Service (DAAD)

Summary:

Although granite is a common lithology in southwestern Cameroon, the age, geologic and geochemical processes that might have led to the concentration of U and Mo in the area remain unknown. Therefore, data on geochemistry of the host plutons as well as ore mineralogy and wall rock alteration were collected. This, together with Re-Os dating on molybdenite, elucidated the genesis of U and Mo mineralization in southwestern Cameroon.

Publications:

Mosoh Bambi, C. K., Frimmel, H. E., Zeh, A., and Suh, C. E., 2013, Age and origin of Pan-African granites and associated U-Mo mineralization at Ekomédion, southwestern Cameroon: Journal of African Earth Sciences, 88, 15-37.

Mosoh Bambi, C.K., Suh, C.E., Nzenti, J.P., Frimmel, H.E., 2012, U-Mo mineralization potential in Pan-African granites, southwestern Cameroon: Economic geology of the Ekomédion prospect. Journal of African Earth Sciences 65, 25-45.

Project duration: 2007 - 2012

Supported by the Robert-Bosch Stiftung and the Chinese Academy of Sciences

Summary:

The Xiaoqinling gold ore field is the second largest gold district in China – the country with thecurrently highest annual gold output in the world. The gold district is located in a basement‐coreduplift along the southern margin of the North China Craton within the Qinling orogenic belt. Thegenesis of the gold‐molybdenite mineralization there has been a matter of controversy. This projectaims at clarifying the timing of and the processes responsible for the gold mineralization.

Publications:

Zhao, H.‐X., Jiang, S.‐Y., Frimmel, H.E., Dai, B.‐Z., Ma, L., 2012, Geochemistry, geochronology and Sr‐Nd‐Hf iosotopes of two Mesozoic granitoids in the Xiaoqinling gold district: Implication for large‐scale lithospheric thinning in the North China Craton. Chemical Geology, 294/295, 173‐189.

Zhao, H.‐X., Frimmel, H.E., Jiang, S.‐Y., Dai, B.‐Z., 2011, LA‐ICP‐MS trace element analysis of pyrite from the Xiaoqinling gold district, China: Implications for ore genesis. Ore Geology Reviews, 43, 142‐153.

Zhao, H.‐X., Jiang, S.‐Y., Frimmel, H.E., 2011, A rare Bi‐Pb tellurosulfide, PbBi4Te4S3, from the Wenyu gold deposit in the Xiaoqinling gold province, China. Canadian Mineralogist 49, 1297‐1304.

Project duration: 2007 - 2011

Summary:

This project concerned the modelling of production cycles of non-renewable georesources, the approximation of the total mineable amount of a given georexource and the prediction of future availability of such resources on a regional and global scale. This research wais aimed at aiding decision makers with regard to formulating policies on securing the future supply of critical georesources.

Publications:

Frimmel, H.E., Müller, J., 2011, Medium-term uranium supply and demand economics. In Barra, F., Reich, M., Campos, E. Tornos, F. (eds.) Let’s Talk Ore Deposits. Proc. 11th Biennial SGA Meeting, 26-29 September 2011, Antofagasta, Ediciones Universidad Católica del Norte, p. 938-940.

Frimmel, H.E., Müller, J., 2011, Estimates of Mineral Resource Availability - How Reliable Are They? -Akad. Geowiss. Geotechn. Veröffentl., 28, 39-62.Frimmel, H.E., Müller, J., 2011, Medium-term uranium supply and demand economics. - In: Barra, F., Reich, M., Campos, E., Tornos, F., eds., Let ́s Talk Ore Deposits. Proc. 11th Biennial SGA Meeting, 26-29 September 2011, Antofagasta, Ediciones Universidad Católica del Norte, 938-940.

Müller, J., Frimmel, H.E., 2011, Abscissa-transforming second order polynomial functions to approximate the unknown historic production of non-renewable resources. Mathematical Geosciences, 43, 625-634.

Müller, J., Frimmel, H.E., 2010, Numerical analysis of historic gold production cycles and implications for future sub-cycles. The Open Geology Journal 4, 35-40.

Frimmel, H.E. (2008): Earth ́s continental crustal gold endowment. Earth and Planetary Science Letters, 267, 45-55.

Frimmel, H.E. (2007): Gold Endowment of the earth ́s crust Over Time. - In: Andrew, C. et al. (eds.), Digging Deeper, Proc. 9th Biennial SGA Meeting, 20-23. 8. 2007, Irish Assoc. Econ. Geol., Dublin, 1, 11-14.

Project duration: 2006 - 2012

Supported by the German Research Foundation (DFG)

Summary:

The siliciclastic Mesoarchaean Witwatersrand Supergroup in the central Kapvaal Craton (SouthAfrica) has hosted close to 30% of all known gold. In spite of its enormous economic significance, thegenesis of this gold remains unresolved. The currently available data and observations are bestexplained by a modified palaeoplacer model. The question of the ultimate source of the hugeamounts of inferred detrital gold remains, however, unanswered and formed the main focus of thisresearch project. The working hypothesis was that the detrital gold is, contrary to previous ideas, notderived from older, hydrothermal gold‐quartz veins in the hinterland but from finely dispersedmagmatic gold in Mesoachaean greenstone belts.

Previous work on the immediate basement of the Witwatersrand Basin had focused on granitoids,whereas this project was aimed at mafic rocks, their tectonic setting and their potential to transferlarge amounts of Au from the mantle into the continental crust. In the first stage of this project, oneof very few existing drill core intersections of such mafic rocks underneath basement granite wasinvestigated petrologically and geochemically. The obtained results suggest that both mafic and felsicintrusives are cogenetic and reflect the products of fractional crystallization of an H2O‐rich,calcalkaline, mantle‐derived melt in a supra‐subduction setting that compares well with some of themost effective modern systems for the transfer and concentration of gold from the mantle into the continental crust.

In the second phase of the project, the encouraging and in certain respects surprising results fromthe first phase were tested, verified (or otherwise) by independent methods, specifically isotopicones, and by comparison with other mafic/felsic rock associations in the close hinterland of theWitwatersrand Basin. In addition, the strength of the underlying hypothesis of the Witwatersrandgold being derived from magmatic gold was tested by assessing the role of petroleum in thetransport of Au into its crustal position. To that effect, widespread pyrobitumen in theWitwatersrand conglomerates was analyzed, for the first time, for its PGE and Au concentrations. The results obtained revealed considerable high‐temperature alteration in one part of the likely hinterland to the Central Rand Basin, whose basin fill represents the world’s largest accumulation of gold. Although the type of alteration discovered could be amenable to Au‐transport, no specific gold anomaly, that could explain the huge amount of placer gold in the Witwatersrand conglomerates, could be detected in any of the potential source rocks. Thus the question of the ultimate source of the Witwatersrand palaeoplacer gold remains unresolved and will be addressed in a subsequent research project.

Publications:

Koglin, N., Frimmel, H.E., Minter, W.E.L., Brätz, H. (2010): Trace‐element characteristics of different pyrite types in Mesoarchaean to Palaeoproterozoic placer deposits. Mineralium Deposita, 45, 259‐280.

Koglin, N., Frimmel, H.E., Minter, W.E.L., Brätz, H. (2010): Trace‐element characteristics of different pyrite types from Mesoarchaean to Palaeoproterozoic placer deposits.‐ In: William, P. et al. (eds.), Smart Science for Exploration and Mining, Proc. 10th Biennial SGA Meeting, 17‐20. 8. 2009, Townsville, 1, 363‐365.

Koglin, N., Zeh, A., Frimmel, H.E., Gerdes, A. (2010): New constraints on the auriferous Witwatersrand sediment provenance from combined detrital zircon U‐Pb and Lu‐Hf isotope data for the Eldorado Reef (Central Rand Group, South Africa). Precambrian Research, 183, 817‐824.

Frimmel, H.E., Emsbo, P., Koenig, A.E. (2009): The source of Witwatersrand Gold: Evidence from uraninite chemistry. ‐ In: William, P. et al. (eds.), Smart Science for Exploration and Mining, Proc. 10th Biennial SGA Meeting, 17‐20. 8. 2009, Townsville, 1, 353‐355.

Frimmel H.E., Zeh, A., Lehrmann, B., Hallbauer, D.K., Frank, W. (2009): Geochemical and geochronological constraints on the nature of the immediate basement beneath the Mesoarchaean auriferous Witwatersrand Basin, South Africa. Journal of Petrology, 50, 2187‐2220.

Lehrmann, B., Frimmel, H.E. (2007): Mesoarchaean Basement of the Witwatersrand: A Possible Source of the Gold? ‐ In: Andrew, C. et al. (eds.), Digging Deeper, Proc. 9th Biennial SGA Meeting, 20‐23. 8. 2007, Irish Assoc. Econ. Geol., Dublin, 1, 15‐18.

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