Geochronological Compilation of the Trans-Hudson Orogen and Environs, Baffin Island And

Geochronological compilation of Trans-Hudson Orogen in Ungava Peninsula

Authors: N. Wodicka and K. Breitsprecher

Introduction

This compilation represents published geochronological information on rocks from Trans- Hudson Orogen in Ungava Peninsula, northern Quebec. For each dated rock sample, a record containing basic information on geological setting, rock description, sample location, analytical method, age, interpretation, and literature citation is given. The analytical methods included in the compilation are U/Pb, K/Ar, Rb/Sr, and Pb/Pb. An accompanying Nd-Sm compilation is available separately on this DVD. The full geochronological compilation also forms part of the Canadian Geochronology Knowledgebase (http://gdr.ess.nrcan.gc.ca/geochron/e/explorer.htm).

The majority of published data are not accompanied by precise sample location information (e.g., without latitude and longitude or UTM coordinates). In these cases, coordinates were either estimated or digitized from available location and geological maps or aerial photographs. In other cases, sample locations given in pre-1970 publications (e.g., Beall et al. 1963) fail to fit the geology on more recent geological maps and should be treated with caution. It should also be noted that sample locations given in this DVD are more accurate than those shown on GSC Open File 4930 (St-Onge et al. (2006). Finally, papers without adequate sample location information are not included in this compilation (e.g., Luck and Allègre 1984; EPSL 68: 205-208; Shirey and Barnes 1994; Mineral. Mag. 58A: 835-836).

Database Structure

To assist the user in interpreting the information provided in the compilation, a description of the fields and general principles followed in preparing the entries in database table “Ungava geochron compilation.dbf” is provided below. However, the user is encouraged to consult the original data source to verify the data and their interpretation.

[SAMPLE] - Sample number as given in the original data source or one assigned to uniquely identify the analyzed sample(s) (abbreviations used in assigned sample numbers include: Ap = aplite; Gd = granodiorite; Gn = gneiss; Gr = granite; Ms = metasedimentary rock; Peg = pegmatite) [ROCK_TYPE] - Broad categorization of rock into one of four types: Plutonic, Volcanic, Sedimentary, or Metamorphic [GEOLOCALE] - Description of the geological framework of a given sample based on St-Onge et al.’s (in press, Tectonics) nomenclature (see Fig. 1 below). These include the following terms: Superior margin, Trans-Hudson Orogen Superior margin (Cape Smith Belt), Trans-Hudson Orogen (i.e. for samples in Povungnituk and Chukotat groups) Ophiolite (Cape Smith Belt), Trans-Hudson Orogen Narsajuaq terrane, Trans-Hudson Orogen Narsajuaq terrane (Cape Smith Belt), Trans-Hudson Orogen (i.e. for samples in Parent and Spartan groups) A question mark (?) refers to samples for which the geological location is uncertain (e.g., Beall et al., 1963). [GEOLUNIT] - Main geological unit (e.g., tectonostratigraphic name, batholith name) as given in the original data source or one assigned based on location of sample on recent geological maps. A question mark (?) refers to samples for which the geological unit is uncertain (e.g., Beall et al., 1963). [ROCKDESC] - Brief description of rock lithology and petrography as given in the original data source. Mineral abbreviations are after Kretz (1983; Am. Mineral. 68: 277-279) or from the listing of symbols for rock and ore-forming minerals at http://www.mineralogicalassociation.ca/doc/symbols.pdf [LOCATION] B Geographic location of sample (e.g., North of Sugluk Inlet, Hudson Strait, northern Quebec) [UTM_ZONE] B UTM zone, NAD 83 [EASTING] B UTM easting coordinate, NAD 83 [NORTHING] B UTM northing coordinate, NAD 83 [NTS] B NTS sheet number at the 1:50 000 scale [AGE_MA] - The interpreted age of the rock or mineral given in millions of years (Ma). Pre- 1977 ages have been corrected to the recommended decay constants of Steiger and Jäger (1977; EPSL 36: 359-362). [ERR_PLUS] - 2 sigma positive uncertainty in Ma. This uncertainty is 0 when no error is given in the original data source. [ERR_MINUS] - 2 sigma negative uncertainty in Ma. This uncertainty is 0 when no error is given in the original data source. [AGE_METHOD] - Isotopic system or methodology used to derive the age (e.g., U/Pb, Rb/Sr, K/Ar, etc.). [AGE_MATER] - The mineral (e.g., zircon, monazite, etc.) or material (e.g., whole rock) analyzed [AGE_INTERP] - A general category that describes the type of geological event dated (e.g., cooling, igneous crystallization, etc.). “No Age” refers to ages for which a unique interpretation is not possible. [AGE_QUALI] - A qualifier describing constraints on the age. "Direct" refers to analytical errors that are statistically representative; "Estimate" is used when the author(s) indicate no statistical validity to assigned errors. Other qualifiers include "Maximum Direct" (i.e. statistical limit on how old the sample can be) and "Minimum Direct" (i.e. statistical limit on how young the sample can be) [AGE_TECHNI] - The analytical technique used to determine the age (e.g., SHRIMP, TIMS) [AGE_NOTE] - A text descriptor highlighting salient features used by the author(s) in arriving at the published interpretation of the date. These features may include brief analytical details (e.g., quality of separate in the case of K/Ar ages), number of data points used in regression calculations, type of regression where given, quality of fit for regressed data or weighted averages, uncertainties in age interpretations, etc. [AUTHORS] - Author(s) of data source [YEAR] - Year of publication [TITLE] - Title of publication (blank if a thesis) [JOURNAL] – Title of Journal, Government report, or thesis [VOLUME] – Volume of Journal [FIRST_PAGE] – First page number of Journal publication or Government report (or total number of pages for a thesis) [LAST_PAGE] - Last page number of Journal publication or Government report

Corrections and Additions

Every attempt was made to include all published radiometric ages but as with any database there are undoubtedly omissions or mistakes. If you detect any ages that should be included in this knowledgebase or any mistakes, please send the information to the attention of Natasha Wodicka, Natural Resources Canada, Geological Survey of Canada, 601 Booth Street, Ottawa, ON, Canada K1A 0E8. Phone (613) 947-4795; Fax: (613) 995-7997; E-mail: [email protected].

Acknowledgements

Sarah McMullen contributed greatly to the early stages of this compilation. Eric de Kemp, Angela Ford, Ingrid Henderson, Mike Villeneuve, and particularly Linda Richard provided invaluable computer assistance. We would also like to thank Marc St-Onge for providing sample location maps and aerial photographs.

Data sources

Beall, G.H., Hurley, P.M., Fairbairn, H.W., and Pinson, J.W.H. 1963. Comparison of K-Ar and whole-rock Rb-Sr dating in New Quebec and Labrador. American Journal of Science, 261: 571-580.

Brévart, O., Dupré, B., and Allègre, C.J. 1986. Lead-lead age of komatiitic lavas and limitations on the structure and evolution of the Precambrian mantle. Earth and Planetary Science Letters, 77: 293-302.

Doig, R. 1983. Rb-Sr isotopic study of Archean gneisses north of the Cape Smith fold belt, Ungava, Quebec. Canadian Journal of Earth Sciences, 20: 821-829.

Doig, R. 1987. Rb-Sr geochronology and metamorphic history of Proterozoic to early Archean rocks north of the Cape Smith fold belt, Quebec. Canadian Journal of Earth Sciences, 24: 813-825.

Dunphy, J.M. 1995. Magmatic Evolution and Crustal Accretion in the Early Proterozoic: the Geology and Geochemistry of the Narsajuaq Terrane, Ungava Orogen, Northern Québec. Ph.D. thesis, Université de Montréal, Montréal, Québec, 333 p.

Dunphy, J.M., Ludden, J.N., and Parrish, R.R. 1995. Stitching together the Ungava Orogen, northern Quebec: geochronological (TIMS and ICP-MS) and geochemical constraints on late magmatic events. Canadian Journal of Earth Sciences, 32: 2115-2127.

Hegner, E., and Bevier, M.L. 1991. Nd and Pb isotopic constraints on the origin of the Purtuniq ophiolite and early Proterozoic Cape Smith Belt, northern Québec, Canada. Chemical Geology, 91: 357-371.

Hunt, P.A., and Roddick, J.C. 1992. A compilation of K-Ar ages, Report 21. Radiogenic Age and Isotopic Studies: Report 5, Geological Survey of Canada, Paper 91-2, pp. 207-261.

Lowdon, J.A. 1961. Age Determinations by the Geological Survey of Canada, Report 2 - Isotopic Ages; Geological Survey of Canada, Paper 61-17, 127 p.

Machado, N., David, J., Scott, D.J., Lamothe, D., Philippe, S., and Gariépy, C. 1993. U-Pb geochronology of the western Cape Smith Belt, Canada: new insights on the age of initial rifting and arc magmatism. Precambrian Research, 63: 211-223.

Parrish, R.R. 1989. U-Pb geochronology of the Cape Smith Belt and Sugluk Block, northern Quebec. In Tectonic, Magmatic and Metallogenic Evolution of the Early Proterozoic Cape Smith Thrust Belt. Edited by S.B. Lucas, C. Picard, and M.R. St-Onge. Geoscience Canada, 16: 126-130.

Scott, D.J., and St-Onge, M.R. 1995. Constraints on the Pb closure temperature in titanite based on rocks from the Ungava orogen, Canada: Implications for U-Pb geochronology and P- T-t path determinations. Geology, 23: 1123-1126.

Taylor, F.C., and Loveridge, W.D. 1985. A Rb-Sr study of granitoid intrusive rocks of the Cape Smith Belt, northern Quebec. In Current Research, Part A, Geological Survey of Canada, Paper 85-1A, pp. 65-67.

Wanless, R.K., Stevens, R.D., Lachance, G.R., and Delabio, R.N.D. 1974. Age Determinations and Geological Studies, K-Ar Isotopic Ages, Report 12; Geological Survey of Canada, Paper 74-2, 72 p.

Wanless, R.K., Stevens, R.D., Lachance, G.R., and Rimsaite, J.Y.H. 1966. Age Determinations and Geological Studies, K-Ar Isotopic Ages, Report 6; Geological Survey of Canada, Paper 65-17, 101 p.