Lithogeochemistry of Geological Units of the Commissaires Lake Area

The following tables present lithogeochemical processing of geological units in the Commissaires Lake area. Descriptions of these units are available in the Bulletin géologiQUE of this area. The 227 analyses used for this processing are from samples collected during the Ministère’s mapping campaign in summer 2018. The analyses selected are those of stratigraphic units considered relevant for lithogeochemical processing. These analyses were conducted by Actlabs in Ancaster, Ontario.

The majority of these samples were analyzed for major oxides, trace elements and base metals. A few selected samples of mafic to ultramafic rocks were also analyzed for platinum, palladium and gold. Analyses were performed by various element-specific techniques such as inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma atomic emission spectroscopy (ICP-AES) and instrumental neutron activation analysis (INAA).

The CIPW norm including biotite and hornblende was calculated for the diagram classification of intrusive and intermediate rocks according to Hutchison (1974, 1975), as described by Janoušek et al. (2006) in the Geochemical Data Toolkit (GCDkit) software. The latter has been used to make all geochemical diagrams listed in the tables below.

Felsic and Intermediate Intrusive Rocks

Stratigraphic Unit

Classification

Affinity

Rare Earth Element (REE) Diagram

Setting

Rhéaume Intrusive Suite (mPrhe2)

(4 samples)

Syenogranite, quartz syenite and mangerite

(Diagram)

K-rich units (shoshonitic series type)

(Diagram)

 

Negative slope diagram (light REE enrichment vs. heavy REE)

Negative to slightly positive Eu anomaly

(Diagram)

Anorogenic

(Diagram)

Jobber Mangerite (mPjob)

(1 sample)

Mangerite-syenite

(Diagram

Shoshonitic series type

(Diagram)

Negative slope diagram and positive Eu anomaly

(Diagram)

Mostly anorogenic

(Diagram)

Leda Intrusive Suite (mPled)

(12 samples)

Quartz monzonite, granite, syenite, monzonite, mangerite, hypersthene quartz diorite and alkali feldspar granite

(Diagram

Units more enriched in K (shoshonitic series type) and calc-alkaline facies

(Diagram)

Negative slope diagram and generally positive Eu anomaly, except for alkali feldspar granite which has a strong positive Eu anomaly

(Diagram)

Léo Plutonic Suite (mPleo)

(1 sample)

Hypersthene granite (charnockite)

(Diagram

K-rich calc-alkaline unit

(Diagram)

Light REE enrichment vs. heavy REE, slight positive Eu anomaly

(Diagram)

Lachance Mangerite (mPlhc)

(3 samples)

Quartz monzonite (mangerite), quartz syenite and granite (syenogranite)

(Diagram)

K-rich calc-alkaline to shoshonitic series type

(Diagram)

For the three units:

– generally negative slope diagram (light REE enrichment vs. heavy REE);  

Eu anomalies varying from positive to negative.

(Diagram)

Mostly anorogenic

(Diagram)

Bonhomme Plutonic Suite (mPboh)

(6 samples)

Quartz ± hypersthene diorite, quartz monzonite (mangerite) and granite (adamellite)

(Diagram)

Calc-alkaline to mostly shoshonitic series type

(Diagram)

Bardeau Plutonic Suite (mPbad)

(17 samples)

Granite, alkali feldspar granite, quartz diorite, granodiorite, mangerite (plot in the monzogabbro field since it is rich in ferromagnesian minerals), tonalitic mobilisate migmatitic mangerite

(Diagram)

K-rich calc-alkaline unit

(Diagram)

Thaddé Plutonic Suite (mPthd)

(10 samples)

Granite (charnockite), alkali feldspar granite, quartz monzodiorite, quartz syenite and quartz monzonite (mangerite)

(Diagram)

K-rich calc-alkaline to shoshonitic series type series

(Diagram)

Generally, for the three suites:

– negative slope diagram (light REE enrichment vs. heavy REE);

– Eu anomalies varying from positive to negative;

– syenite and alkali feldspar granite more enriched in light REE. 

(Diagram)

Mostly anorogenic for the alkaline facies of the three suites

(Diagram)

Mimosa Plutonic Suite (mPmim)

(13 samples)

Granite, granodiorite (opdalite, charnockite), monzonite, monzodiorite and diorite. All these lithologies can contain quartz and hypersthene.

(Diagram)

Mostly calc-alkaline series to shoshonitic series type

(Diagram)

Marianne Plutonic Suite (mPmae)

(6 samples)

Granite (charnockite), alkali feldspar granite, syenite, quartz ± hypersthene syenite, quartz diorite

(Diagram)

Mostly shoshonitic series type

(Diagram)

Travers Suite (mPtra)

(37 samples)

Syenite ± quartz ± hypersthene, granite (syenogranite), alkali feldspar granite, monzonite, quartz monzonite and mangerite (plot in the field of quartz monzodiorites since mangerite contains >20% ferromagnesian minerals)

(Diagram)

K-rich calc-alkaline series to shoshonitic series type

(Diagram)

 

Generally, all lithologies of the suite show these characteristics:

– negative slope diagram (light REE enrichment vs. heavy REE);

Eu anomalies varying from positive to negative;

Outcrop 18-AM-2019 shows a less pronounced negative slope diagram and a strong positive Eu anomaly.

(Diagram)

Mostly anorogenic

(Diagram)

Sainte-Hedwidge Intrusive Suite (mPshe)

(5 samples)

Granite, quartz monzonite and quartz monzodiorite

(Diagram)

Generally, both suites are of shoshonitic series type

(Diagram)

Generally, both suites show these characteristics:

– negative slope diagram (light REE enrichment vs. heavy REE);

–  Eu anomalies varying from positive to negative.

 

(Diagram)

Anorogenic for both suites

(Diagram)

Rodez Plutonic Suite (mPrdz1)

(13 samples)

Granite (adamellite), syenite, quartz monzonite, quartz syenite, quartz diorite, all lithologies ± hypersthene

(Diagram)

 

Mafic and Ultramafic Intrusive Rocks

Stratigraphic Unit

Lithology

Affinity

Tectonic Setting

Claire Gabbronorite (mPclr)

(21 samples)

Gabronorite ± Fe-Ti ± P ± V oxides and ultramafic rock

 

 

 

 

 

 

Tholeiitic to calc-alkaline

(Diagram)

 

 

Mafic rocks mostly plot in the field of intraplate basalts.

(Diagram)

Roc Suite (mPsro2)

(10 samples)

Gabronorite ± Fe-Ti ± P ± V oxides

 

Mafic rocks are mainly divided between the fields of intraplate basalts and mid-oceanic ridge basalts.

(Diagram)

Rodez Plutonic Suite (mPrdz2)

(10 samples)

Anorthosite, leuconorite, gabbronorite ± rich in Fe-Ti ± P ± V

Tholeiitic

(Diagram)

 

Gabbronorite belonging to the:

Thaddé Plutonic Suite (mPthd)

(2 samples)

Sainte-Hedwidge Intrusive Suite (mPshe)

(2 samples)

Marianne Plutonic Suite (mPmae)

(4 samples)

Léo Intrusive Suite (mPleo)

(1 sample)

Travers Suite (mPtra)

(5 samples)

Gabbro, gabbronorite and ultramafic rock 
 

(Diagram)

Mainly calc-alkaline

(Diagram)

 

Mafic rocks of the Thaddé Plutonic Suite, Sainte-Hedwidge Intrusive Suite and Marianne Plutonic Suite plot in the field for intraplate “basalts”, while rocks of the Travers Suite correspond to those defined for the intraplate, mid-oceanic ridges and island arc “basalts”. Other samples of the Léo Plutonic Suite and Travers Suite are out of scope in the diagram.

(Diagram)

Sedimentary Rocks

Stratigraphic Unit Lithology Protolith and Alteration  

Barrois Complex (mPboi4)

(14 samples)

Biotite paragneiss, quartzite, calcosilicate rocks and granite

Weakly altered metasedimentary rocks, likely derived from tonalite and granite

(Diagram)

 

 

 

Wabash Complex (mPwab1, mPwab2)

(30 samples)

Biotite ± sillimanite ± graphite ± garnet paragneiss, migmatitic paragneiss, quartzite, calcosilicate rocks, marble, migmatite derived from sedimentary rock

Biotite ± sillimanite ± graphite ± garnet paragneiss showing a trend towards the illite pole

More altered paragneiss than those of the Barrois Complex 

Paragneiss derived from a felsic protolith (tonalite, granodiorite, granite)

(Diagram)

 

 

References

Other publications

DEBON, F., LEFORT, P., 1983. A chemical-mineralogical classification of common plutonic rocks and associations. Transactions of the Royal Society of Edinburgh, Earth Sciences; volume 73, pages 135-149. doi.org/10.1017/S0263593300010117.

DE LA ROCHE, H., LETERRIER, J., GRANDCLAUDE, P., MARCHAL, M. 1980. A classification of volcanic and plutonic rocks using R1-R2 diagrams and major element analyses – its relationships with current nomenclature. Chemical Geology; volume 29, pages 183–210. doi.org/10.1016/0009-2541(80)90020-0.

HARRIS, N.B.W., PEARCE, J.A., TINDLE, A.G. 1986. Geochemical characteristics of collision-zone magmatism. In COWARD, M.P. and REIS, A.C. (eds.), Collision tectonics. Geological Society, London; Special Publications; volume 19, pages 67-81. doi.org/10.1144/GSL.SP.1986.019.01.04.

HUTCHISON, C.S. 1974. Laboratory handbook of petrographic techniques. John Wiley & Sons, New York. 527 p.

HUTCHISON, C.S. 1975. The norm, its variations, their calculation and relationships. Schweizerische Mineralogische und Petrographische Mitteilungen (Swiss Bulletin of Mineralogy and Petrology); Volume 55, pages 243-256.

IRVINE, T. N., BARAGAR, W.R.A. 1971. A guide to the chemical classification of the common volcanic rocks. Canadian Journal of Earth Sciences; volume 8, pages 523–548. doi.org/10.1139/e71-055.

JANOUŠEK, V., FARROW, C.M., ERBAN, V. 2006. Interpretation of whole-rock geochemical data in igneous geochemistry: introducing Geochemical Data Toolkit (GCDkit). Journal of Petrology; volume 47, pages 1255–1259. doi.org/10.1093/petrology/egl013.

MCDONOUGH, W.F., SUN, S.S. 1995. The composition of the earth. Chemical Geology; volume 120, pages 223–253. doi.org/10.1016/0009-2541(94)00140-4.

NESBITT, H.W., 2003. Geochemistry of Sediments and Sedimentary Rocks: Evolutionary Consideration to Mineral Deposit-Forming Environments. Geological Association of Canada; volume 4, pages 39–51.

PEARCE, J.A., NORRY, M.J. 1979. Petrogenetic implications of Ti, Zr, Y, and Nb variations in volcanic rocks. Contributions to Mineralogy and Petrology; volume 69, pages 33-47. doi.org/10.1007/BF00375192

PECCERILLO, A., TAYLOR, S.R., 1976. Geochemistry of Eocene calc-alkaline volcanic rocks from the Kastamonu area, Northern Turkey. Contributions to Mineralogy and Petrology; volume 58, pages 63–81. doi.org/10.1007/BF00384745.

WHALEN J.,B., CURRIE K., CHAPPELL, B.W. 1987. A-type granites: geochemical characteristics, discrimination and petrogenesis. Contributions to Mineralogy and Petrology; volume 95, pages 407–419. doi.org/10.1007/BF00402202.

19 novembre 2019