Geological Survey of Canada Open File 5645
Flin Flon TGI3 Digital Compilation of Shield Margin NATMAP Nd Isotopic and Geochemical Data
Authors: J.B. Whalen1, R.A. Stern2, N. Rayner1,E.C. Syme3, A.H. Bailes3, H.V. Zwanzig3, K.E. Ashton4, W.L. Slimmon4
- Geological Survey of Canada, 601 Booth Street, Ottawa, ONK1A 0E8, Canada,.
- Minerals Division, Geoscience Australia, GPO Box 378, Canberra, ACT 2601, Australia.
- Manitoba Geological Survey, ManitobaScience, Technology, Energy and Mines, 1395 Ellice Avenue, Winnipeg, MBR3G 3P2, Canada,
- Saskatchewan Geological Survey, Saskatchewan Industry and Resources, 300 - 2103 - 11th Avenue, Regina,SKS4P 3Z8, Canada.
Notes
The compilation area lies in the Trans-Hudson orogen, which is dominantly of Paleoproterozoic age but encompasses some Archean basement. For an overview of its geology and tectonic evolution, see NATMAP Shield Margin Project Working Group (1998). This Nd-Sm and geochemical compilation was put together mainly from archived digital files created by the twosenior authors during the Shield Margin NATMAP project. It includes Nd isotopic and geochemical data published in papers by Stern et al. (1995a,b) and Whalen et al. (1999), as well as previously unpublished data collected by the authors. Much of the geochemical data, but none of the Nd isotopic data, was published in Viljoen et al. (2000). Details of analytical methods for Nd isotopic analyses carried out in the Geochronology Laboratory, Geological Survey of Canada (GSC) are described in Thériault (1990). Very similar methods (see Swinden et al., 1990) were employed for analyses carried out under contract at Memorial University of Newfoundland (MUN). Nd isotopic compositions were normalized to 146Nd/144Nd= 0.7219. Repeated measurements of AMES Nd solution yielded 143Nd/144Nd= 0.512194±0.000022 (2 standard deviation (SD)). All 143Nd/144Nd ratios were corrected to La Jolla143Nd/144Nd = 0.511860. It should be noted that ±2 SD values on measured 143Nd/144Nd ratios are only reported for a small subset of samples analyzed at MUN. These values represent MAT 261 machine precision errors obtained at the time of data acquisition for that individual sample. For samples for which such values were unavailable, long-term reproducibility of standard analyses for 143Nd/144Nd ratios at the GSC during the early 1990’s was ±0.000020 (2 SD). Also, the maximum error on measured 147Sm/144Nd ratios was ±0.5% and the estimated error on an individual εNd calculation is ±0.5 units. Crustal extraction ages (in Ga) have been calculated from the Nd isotopic data using both the DePaolo (1981) and Goldstein et al. (1984) models.Model ages have only been calculated for samples for which the 147Sm/144Nd ratio is <0.15. Comparison of model ages with crystallization ages for juvenile (+εNd ) samples in this compilation indicates those based on the DePaolo (1981) model correspond more closely to U-Pb igneous crystallization ages, whereas Goldstein et al. (1984) model ages are consistently too old. For geochemical analyses, information concerning analytical methods and lab sources are given in the above cited sources. Where rare earth elements were among the trace elements analyzed from individual samples contained in this compilation, the generally close correspondence between Nd and Sm determined by isotope dilution and another method helps substantiate the reliability of the remaining trace element data. Mineral name abbreviations follow Kretz (1983).
Keywords: Nd isotopes, geochemistry, Paleoproterozoic, Flin Flon, Trans-Hudson, Manitoba, Saskatchewan
Published Data Sources
DePaolo, D.J. (1981): Neodymium isotopes in the Colorado Front Range and crust-mantle evolution in the Proterozoic. Nature, v. 291, p. 193-196.
Goldstein, S.L., O’Nions, R.K. and Hamilton, P.J. (1984): A Sm-Nd study of atmospheric dusts and particulates from major river systems. Earth and Planetary Science Letters, v. 70, p. 221-236.
Kretz, R. (1983): Symbols for rock forming minerals; American Mineralogist, v. 68, p. 277-279.
Thériault, R.A., 1990. Methods for Rb-Sr and Sm-Nd isotopic analyses at the Geochronology Laboratory, Geological Survey of Canada. In: Radiometric Age and Isotopic Studies: Report 3, Geological Survey of Canada Paper 89-2, p. 3-6.
NATMAP Shield Margin Project Working Group 1998. Geology, NATMAP Shield Margin Project Area (Flin Flon Belt), Manitoba-Saskatchewan; Geological Survey of Canada Map 1968A, Mantitoba Energy and Mines Map A-98-2, Sheets 1 to 7, Saskatchewan Energy and Mines Map 258A-2, scale 1:100 000.
Stern, R.A., Syme, E.C., Bailes, A.H., and Lucas, S.B., 1995a.Paleoproterozoic (1.90-1.86 Ga) arc volcanism in the Flin Flon Belt, Trans-Hudson Orogen, Canada; Contributions to Mineralogy and Petrology, v. 119, p. 117-141.
Stern, R.A., Syme, E.C., and Lucas, S.B., 1995b.Geochemistry of 1.9 Ga MORB- and OIB-like basalts from the Amisk collage, Flin Flon Belt, Canada: Evidence for an intra-oceanic origin; Geochimica et Cosmochimica Acta, v. 59, p. 3131-3154.
Swinden, H.S., Jenner, G.A., Fryer, B.J., Hertogen, J. and Roddick, J.C., 1990. Petrogenesis and paleotectonic history of the Wild Bight Group, and Ordovician rifted island arc in central Newfoundland. Contributions to Mineralogy and Petrology, v.105, p. 219-241.
Viljoen, D., Chackowsky, L., Lenton, P., Vanderkam, R., Broome, H.J., Slimmon, B. and the NATMAP Shield Margin Project Working Group, 2000. Selected data from the NATMAP Shield Margin Project Database; Geological Survey of Canada, Manitoba Energy and Mines, and Saskatchewan Energy and Mines, GSC OF D3884 / MEM OF 98-1 / SEM OF 2000-2.
Whalen, J.B., Syme, E.C., and Stern, R.A., 1998. Geochemical and Nd isotopic evolution of Paleoproterozoic arc-type magmatism in the Flin Flon Belt, Trans-Hudson Orogen, Canada; Canadian Journal of Earth Sciences, v.35, p. 227-250.
Database structure and explanations
To assist the user in interpreting the information provided in the compilation, descriptive notes concerning selected fields and general principles followed in preparing these entries in the spreadsheet/database table are provided below. Column headings, shown in bold and enclosed in square brackets below, employ capitals throughout and ‘_’ rather than spaces, to facilitate conversion from spreadsheet to database format. The user is encouraged to consult published papers listed above(and/or sources cited therein)to verify the compiled data and their interpretation.
[SAMPLE] - Sample number as assigned by the sample collector.
[ZONE] - UTM zone, NAD 27
[EASTING] - UTM easting coordinate, NAD 27
[NORTHING] - UTM northing coordinate, NAD 27
[AREA] – Geographic/geological areas : ATHA – Athapapuskow Lk, ELBOW – Elbow Lk, FFWL – Flin Flon – White Lk, KISS – Kisseynew belt, SNOW – Snow Lk, WAMISK – West Amisk Lk.
[CLASS] – Sample classification: p = plutonic; v = volcanic; s = sedimentary
[ASSEMBLAGE] – For plutonic samples: ev = evolved arc; eja = early juvenile arc; for post accretion arc, esa = early stage; msa = middle stage; lsa = late stage; see Whalen et al. (1999) for details; for volcanic samples: arc = volcanic arc affinity; oib = ocean island affinity; of = ocean floor affinity; sho = shoshonitic affinity; see Stern et al. (1995a,b) for details; if not known = NK
[UNIT] - Main geological unit. Names generally follow those employed in GSC Map 1968A.
[LITHOLOGY] - Rock description.Mineral abbreviations are after Kretz (1983); fg, fine-grained; mg, medium-grained; cg, coarse-grained; vcg, very coarse-grained; eq, equigranular; fol, foliated; porph, porphyritic
[E143ND_T] – ε143Nd value is calculated for theigneous crystallization or depositionalage (T) specified in [Age_Ma] relative to the accepted Chondritic Uniform Reservoir (CHUR) with 143Nd/144Nd=0.512638 and 147Sm/144Nd=0.1967.
[TDM_GOLD] - TDM model age (Ga) calculated according to the depleted mantle parameters of Goldstein et al. (1984) for samples with 147Sm/144Nd < 0.15 (NC = not calculated for samples with 147Sm/144Nd > 0.15)
[TDM_DEP] - TDM model age (Ga) calculated according to the depleted mantle parameters of DePaolo (1981) for samples with 147Sm/144Nd < 0.15 (NC = not calculated for samples with 147Sm/144Nd > 0.15).
[AGE_MA] & [SOURCE]- Real (r) age of rock unit (age not necessarily determined at same sample location as Nd isotopic analysis) based on U-Pb dating or inferred (i) age of rock based on geological relationships or correlation with an actually dated geological unit. Almost all ‘real’ ages were obtained fromU-Pb geochronological compilations that were included in NATMAP Shield Margin Project Working Group (1998); Viljoen et al. (2000) and Whalen et al. (1999); source references and errors associated with these ages are included in these pubications. The oldest dated tonalitic gneiss component (ca. 1888 Ma) from the GantsLake batholith is an unpublished SHRIMP age of Rayner and Whalen (2006).
[143_144_M] - Measured 143Nd/144Nd ratio
[2SD] - 2 standard deviation errors (values need to be divided by one millon) on individual 143Nd/144Nd ratio, for most samples this information is not available (see notes above)
[147_144_M] - Measured 147Sm/144Nd ratio
[ND_ID] - Nd concentration in ppm determined by isotope dilution
[SM_ID] - Sm concentration in ppm determined by isotope dilution
[ND-SM_LAB] – Laboratory where isotopic analyses performed: GSC – Geological Survey of Canada, MUN – Memorial University of Newfoundland.
[ND_SM_REF] – First author and publication year of main data source (no year for unpublished data)
[SIO2]….[CO2] – Major element composition in wt.%
[CR]….[LU] – Trace element composition in ppm
[REE_TRACES] – Analytical method of REE (plus various other traces): ICP-MS – induced coupled plasma mass spectrometry, INAA – instrumental neutron activation analyses, none – no REE data available.
[GEOCH_REF] – First author and publication year of main geochemical data source (no year for unpublished data)