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Petrographic and mineralogical characteristics of diagenetic overprinting in Neoproterozoic diamictites from Murchisonfjorden, Nordaustlandet, Svalbard

Szczepan Bal

Szczepan Bal

Institute of Geophysics, Polish Academy of SciencesWarsaw, Poland
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Bal, Szczepan
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Krzysztof Nejbert

Krzysztof Nejbert

Department of Geology, University of WarsawWarsaw, Poland
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Nejbert, Krzysztof
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Krzysztof Michalski

Krzysztof Michalski

Institute of Geophysics, Polish Academy of SciencesWarsaw, Poland
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Michalski, Krzysztof
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Justyna Domańska-Siuda

Justyna Domańska-Siuda

Department of Geology, University of WarsawWarsaw, Poland
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Domańska-Siuda, Justyna
, 
Geoffrey Manby

Geoffrey Manby

Natural History MuseumLondon, UK
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Manby, Geoffrey
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Aleksandra Hołda-Michalska

Aleksandra Hołda-Michalska

Institute of Paleobiology, Polish Academy of SciencesWarsaw, Poland
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Hołda-Michalska, Aleksandra
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Jiři Sláma

Jiři Sláma

Institute of Geology of the Czech Academy of SciencesPraha 6, Czech Republic
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Sláma, Jiři
  
28 mars 2025
Petrographic and mineralogical characteristics of diagenetic overprinting in Neoproterozoic diamictites from Murchisonfjorden, Nordaustlandet, Svalbard's Cover Image
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Catégorie d'article: Letter
Publié en ligne: 28 mars 2025
Pages: 23 - 33
Reçu: 26 nov. 2024
Accepté: 15 févr. 2025
DOI: https://doi.org/10.2478/mipo-2025-0004
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© 2025 Szczepan Bal et al., published by Sciendo
This work is licensed under the Creative Commons Attribution 4.0 International License.

Figure 1.

Geological map of southwestern Murchisonfjorden modified after Hoffman et al. (2012) and online interactive geological map available at the NorskPolarinstitutt website (https://www.npolar.no/). Circles/dots represent the sampling locations of the Petrovbreen Member (Mb.)/Wilsonbreen Formation (Fm.) diamictites, respectively. Paleomagnetic site of the Wilsonbreen Fm. diamictite (TILL6), sampled in 2013 and analysed by Michalski et al. (2023), is marked by a star. Stratigraphic column after Halverson et al. (2022) with Re-Os ages after Millikin et al. (2022). BSA – Bittel Spring Anomaly.
Geological map of southwestern Murchisonfjorden modified after Hoffman et al. (2012) and online interactive geological map available at the NorskPolarinstitutt website (https://www.npolar.no/). Circles/dots represent the sampling locations of the Petrovbreen Member (Mb.)/Wilsonbreen Formation (Fm.) diamictites, respectively. Paleomagnetic site of the Wilsonbreen Fm. diamictite (TILL6), sampled in 2013 and analysed by Michalski et al. (2023), is marked by a star. Stratigraphic column after Halverson et al. (2022) with Re-Os ages after Millikin et al. (2022). BSA – Bittel Spring Anomaly.

Figure 2.

Backscattered electron (BSE) images of the diamictite samples from the Petrovbreen Mb. and the Wilsonbreen Fm.; A - Porosity and overgrowing of Fe-rich dolomite on dolomite (RUS st2); B - Porosity in the matrix (marked with an arrow) with secondary diagenetic overprinting of the clast by chlorite and anatase. Detrital dolomite and quartz with visible etched edges (IN st1); C - Euhedral, compositionally zoned dolomite with secondary Fe-rich outer rim, tiny grains of scattered pyrite and anatase (both white in colour) visible in the matrix (RUS st2); D - Micrite limestone clast being partly replaced by dolomite, overgrown first by chlorite (light-grey, crystals arranged in the form of a palisade) and then albite (dark), grey most outer rim consists of new calcite (SPR st1); Ab - albite, Ant – anatase, Cal - calcite, Chl - chlorite, Dol - dolomite, Qz - quartz.
Backscattered electron (BSE) images of the diamictite samples from the Petrovbreen Mb. and the Wilsonbreen Fm.; A - Porosity and overgrowing of Fe-rich dolomite on dolomite (RUS st2); B - Porosity in the matrix (marked with an arrow) with secondary diagenetic overprinting of the clast by chlorite and anatase. Detrital dolomite and quartz with visible etched edges (IN st1); C - Euhedral, compositionally zoned dolomite with secondary Fe-rich outer rim, tiny grains of scattered pyrite and anatase (both white in colour) visible in the matrix (RUS st2); D - Micrite limestone clast being partly replaced by dolomite, overgrown first by chlorite (light-grey, crystals arranged in the form of a palisade) and then albite (dark), grey most outer rim consists of new calcite (SPR st1); Ab - albite, Ant – anatase, Cal - calcite, Chl - chlorite, Dol - dolomite, Qz - quartz.

Figure 3.

Backscattered electron (BSE) images of the diamictite samples from the Petrovbreen Mb. and the Wilsonbreen Fm.; A - Dolomitic clast with outer rim of chlorite (SPR st1); B - Clast of micrite limestone rimmed by late Fe-rich calcite and albite (SPR st2); C - K-feldspar with diagenetic illite distributed along cleavage plains (PPR st2); D - Magmatic clast (granite) with K-feldspar, quartz and plagioclase, partly replaced by clay minerals (PPR st2); Ab - albite, Cal - calcite, Chl - chlorite, Dol - dolomite, Ilt - illite (clay minerals), Kfs - K-feldspar, Pl - plagioclase, Qz - quartz.
Backscattered electron (BSE) images of the diamictite samples from the Petrovbreen Mb. and the Wilsonbreen Fm.; A - Dolomitic clast with outer rim of chlorite (SPR st1); B - Clast of micrite limestone rimmed by late Fe-rich calcite and albite (SPR st2); C - K-feldspar with diagenetic illite distributed along cleavage plains (PPR st2); D - Magmatic clast (granite) with K-feldspar, quartz and plagioclase, partly replaced by clay minerals (PPR st2); Ab - albite, Cal - calcite, Chl - chlorite, Dol - dolomite, Ilt - illite (clay minerals), Kfs - K-feldspar, Pl - plagioclase, Qz - quartz.

Figure 4.

Pyrite and coexisting minerals from the TiO2 group (anatase). A–B - Framboidal pyrite aggregates, partly modified by syntaxial growth of late diagenetic pyrite. Polarized reflected light, one Nicol (A) and crossed Nicols (B), sample SPR st5; C–D - Euhedral pyrite crystals in the carbonate matrix. Tiny grains of anatase co-occur with pyrite. Polarized reflected light, one Nicol (C) and crossed Nicols (D), sample SPR st5; E - Single euhedral pyrite crystal associated with numerous small oval pyrite aggregates that probably represent partly recrystallized framboidal pyrite aggregates. Tiny anatase intergrowths some of which occur as euhedral grains in the carbonate matrix. Polarized reflected light, one Nicol, sample RUS st2; F - Euhedral pyrite partly replaced by late goethite. Polarized reflected light, one Nicol, sample RUS st2; Ant - anatase, Gth - goethite, Py - pyrite.
Pyrite and coexisting minerals from the TiO2 group (anatase). A–B - Framboidal pyrite aggregates, partly modified by syntaxial growth of late diagenetic pyrite. Polarized reflected light, one Nicol (A) and crossed Nicols (B), sample SPR st5; C–D - Euhedral pyrite crystals in the carbonate matrix. Tiny grains of anatase co-occur with pyrite. Polarized reflected light, one Nicol (C) and crossed Nicols (D), sample SPR st5; E - Single euhedral pyrite crystal associated with numerous small oval pyrite aggregates that probably represent partly recrystallized framboidal pyrite aggregates. Tiny anatase intergrowths some of which occur as euhedral grains in the carbonate matrix. Polarized reflected light, one Nicol, sample RUS st2; F - Euhedral pyrite partly replaced by late goethite. Polarized reflected light, one Nicol, sample RUS st2; Ant - anatase, Gth - goethite, Py - pyrite.

Figure 5.

Highly altered detrital grains of Fe-Ti oxides and their alteration products (pseudomorphs after Fe-Ti oxide consists of anatase). Please note the diagnostic white internal reflections visible in (B) and (D). A–B - Anatase pseudomorph after detrital Fe-Ti oxide co-occurred with euhedral pyrite and fine-grained diagenetic anatase. Polarized reflected light, one Nicol (A) and crossed Nicols (B), sample RUS st2; C–D -Anatase pseudomorph after detrital oxy-exsolved titanomagnetite grain. Polarized reflected light, one Nicol (C) and crossed Nicols (D), sample IN st1; E - Anatase pseudomorph after ilmenite, numerous, small anatase grains occur in the carbonate-clay matrix. Polarized reflected light, one Nicol, sample SPR st5; F - Anatase pseudomorph after Ti-magnetite, sample SPR st5. Ant - anatase, psFe-Ti - pseudomorph after Fe-Ti oxide, psIlm - pseudo ilmenite, psMag - pseudo magnetite, Py - pyrite. Red dots (in C and E) indicate points where the S-1 and S-2 Raman spectra were collected. The interpretation of the spectra is given in Fig. 6A.
Highly altered detrital grains of Fe-Ti oxides and their alteration products (pseudomorphs after Fe-Ti oxide consists of anatase). Please note the diagnostic white internal reflections visible in (B) and (D). A–B - Anatase pseudomorph after detrital Fe-Ti oxide co-occurred with euhedral pyrite and fine-grained diagenetic anatase. Polarized reflected light, one Nicol (A) and crossed Nicols (B), sample RUS st2; C–D -Anatase pseudomorph after detrital oxy-exsolved titanomagnetite grain. Polarized reflected light, one Nicol (C) and crossed Nicols (D), sample IN st1; E - Anatase pseudomorph after ilmenite, numerous, small anatase grains occur in the carbonate-clay matrix. Polarized reflected light, one Nicol, sample SPR st5; F - Anatase pseudomorph after Ti-magnetite, sample SPR st5. Ant - anatase, psFe-Ti - pseudomorph after Fe-Ti oxide, psIlm - pseudo ilmenite, psMag - pseudo magnetite, Py - pyrite. Red dots (in C and E) indicate points where the S-1 and S-2 Raman spectra were collected. The interpretation of the spectra is given in Fig. 6A.

Figure 6.

Identification of digenetic minerals using the Raman spectroscopy method. A - Raman spectra of anatase recorded from pseudomorphs after detrital magnetite (spectrum S-1, see Fig. 5C), ilmenite (spectrum S-2, see Fig. 5E), and refined dust-like anatase grains in a carbonate-clay matrix (spectrum S-3); B - Carbonate-clay matrix with fine diagenetic anatase crystals. The red dot marks where the anatase spectrum S-3 were recorded, and a reflected light image was taken from the IN st1 sample; C - Fe-Mg chlorite (chamosite) in paragenetic association with albite. Red dots indicate the Raman analytical points of spectrum S-4 (chamosite) and spectrum S-5 (albite). The image was taken from the SPR st1 sample; D–E - Representative spectra of Fe-Mg chlorite (chamosite) and albite were recorded from the alteration zone surrounding the carbonate clast from the SPR st1 sample.
Identification of digenetic minerals using the Raman spectroscopy method. A - Raman spectra of anatase recorded from pseudomorphs after detrital magnetite (spectrum S-1, see Fig. 5C), ilmenite (spectrum S-2, see Fig. 5E), and refined dust-like anatase grains in a carbonate-clay matrix (spectrum S-3); B - Carbonate-clay matrix with fine diagenetic anatase crystals. The red dot marks where the anatase spectrum S-3 were recorded, and a reflected light image was taken from the IN st1 sample; C - Fe-Mg chlorite (chamosite) in paragenetic association with albite. Red dots indicate the Raman analytical points of spectrum S-4 (chamosite) and spectrum S-5 (albite). The image was taken from the SPR st1 sample; D–E - Representative spectra of Fe-Mg chlorite (chamosite) and albite were recorded from the alteration zone surrounding the carbonate clast from the SPR st1 sample.

Figure 7.

Saturation isothermal remanent magnetization (SIRM) results with the visible presence of magnetite (maximum blocking temperature for magnetite - 575°C) in diamictites; red lines - Petrovbreen Mb., blue lines - Wilsonbreen Fm.
Saturation isothermal remanent magnetization (SIRM) results with the visible presence of magnetite (maximum blocking temperature for magnetite - 575°C) in diamictites; red lines - Petrovbreen Mb., blue lines - Wilsonbreen Fm.

Geographic coordinates (WGS84 reference system) of the diamictite sites sampled in Murchisonfjorden (this study)_

Site Latitude Longitude Stratigraphic unit
IN st1 79.91927 N 18.32933 E Wilsonbreen Fm.
RUS st1 79.97208 N 18.24177 E Wilsonbreen Fm.
RUS st2 79.96948 N 18.23032 E Petrovbreen Mb.
PPR st2 79.94028 N 18.28775 E Wilsonbreen Fm.
SPR st1 79.90663 N 18.13743 E Wilsonbreen Fm.
SPR st2 79.90897 N 18.13895 E Wilsonbreen Fm.
SPR st3 79.90950 N 18.14060 E Wilsonbreen Fm.
SPR st5 79.90877 N 18.17152 E Petrovbreen Mb.
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