Early Ordovician rifting of Avalonia and birth of the Rheic Ocean: U-Pb detrital zircon constraints from Newfoundland

Journal of the Geological Society

Volumn 166, Issue 3, 2009, Pages 501-515

  Pollock, Jeffrey C ^a,b   Hibbard, James P ^a   Sylvester, Paul J ^c  

^a NORTH CAROLINA STATE UNIVERSITY   (United States)

^b UNIVERSITY OF EDINBURGH   (United Kingdom)

^c MEMORIAL UNIVERSITY OF NEWFOUNDLAND   (Canada)

Author keywords

[No Author keywords available]

Indexed keywords

AVALONIA; CALC ALKALINE ROCK; ORDOVICIAN; PALEOZOIC; PROVENANCE; RIFTING; SEDIMENTARY SEQUENCE; TECTONIC EVOLUTION; URANIUM-LEAD DATING; ZIRCON;

CANADA; NEWFOUNDLAND; NEWFOUNDLAND AND LABRADOR; NORTH AMERICA;

BIDENS PILOSA;

EID: 69949106851     PISSN: 00167649     EISSN: None     Source Type: Journal    
DOI: 10.1144/0016-76492008-088     Document Type: Article

References (98)

1. Andersen, T. 2005. Detrital zircons as tracers of sedimentary provenance: limiting conditions from statistics and numerical simulation. Chemical Geology, 216, 249-270.
2. Anderson, M.M., Bruckner, W.D., King, A.F. & Maher, J.B. 1975. The late Proterozoic 'H.D. Lilly Unconformity' at Red Head, northeastern Avalon Peninsula, Newfoundland. American Journal of Science, 275, 1012-1027.
3. Ayuso, R.A., Barr, S.M. & Longstaffe, F.J. 1996. Pb and O isotopic constraints on the source of granitic rocks from Cape Breton Island, Nova Scotia, Canada. American Journal of Science, 296, 789-817.
4. Barr, S.M., Davis, D.W., Kamo, S. & White, C.E. 2003. Significance of U-Pb detrital zircon ages in quartzite from peri-Gondwanan terranes, New Brunswick and Nova Scotia, Canada. Precambrian Research, 126, 123-145.
5. Benus, A.P. 1988. Sedimentological context of a deep-water Ediacaran fauna (Mistaken Point, Avalon Zone, eastern Newfoundland). In: Landing, E., Myrow, P. & Narbonne, G. (eds) Trace Fossils, Small Shelly Fossils and the Precambrian-Cambrian Boundary. New York State Museum and Geological Survey Bulletin, 463, 8-9.
6. Bettencourt, J.S., Tosdal, R.M., Leite, W.B. & Payolla, B.L. 1999. Mesoproterozoic rapakivi granites of the Rondônia Tin Province, south-western border of the Amazon Craton, Brazil. Reconnaissance U-Pb geochronology and regional implications. Precambrian Research, 95, 41-67.
7. Bevier, M.L. & Barr, S.M. 1990. U-Pb age constraints on the stratigraphy and tectonic history of the Avalon terrane, New Brunswick, Canada. Journal of Geology, 58, 53-63.
8. Brasier, M., Cowie, J. & Taylor, M. 1994. Decision on the Precambrian Cambrian boundary stratotype. Episodes, 17, 3-8.
9. Brenchley, P.J., Pickerill, R.K. & Stromberg, S.G. 1993. The role of wave reworking on the architecture of storm sandstone facies, Bell Island Group (Lower Ordovician), eastern Newfoundland. Sedimentology, 40, 359-382.
10. Calon, T. 2001. Late Precambrian sedimentation and related orogenesis of the Avalon Peninsula, eastern Avalon Zone, Newfoundland. Geological Association of Canada, St. John's 2001 Field Trip Guidebook, A9/B8, 1-32.
11. Cawood, P.A., McCausland, P.J.A. & Dunning, G.R. 2001. Opening Iapetus: Constraints from the Laurentian margin in Newfoundland. Geological Society of America Bulletin, 113, 443-453.
12. Cawood, P.A., Nemchin, A.A., Smith, M. & Loewy, S. 2003. Source of the Dalradian Supergroup constrained by U-Pb dating of detrital zircon and implications for the East Laurentian margin. Journal of the Geological Society, London, 160, 231-246.
13. Cocks, L.R.M., McKerrow, W.S. & van Staal, C.R. 1997. The margins of Avalonia. Geological Magazine, 134, 627-636.
14. Dall'Agnol, R., Costi, H.T., Leite, A.A., Magalhaes, M.S. & Teixeira, N.P.1999. Rapakivi granites from Brazil and adjacent areas. Precambrian Research, 95, 9-39.
15. Davis, D.W. 2002. U-Pb geochronology of Archean metasediments in the Pontiac and Abitibi subprovinces, Quebec, constraints on timing, provenance and regional tectonics. Precambrian Research, 115, 97-117.
16. Dec, T., O'Brien, S.J. & Knight, I. 1992. Late Precambrian volcaniclastic deposits of the Avalonian Eastport basin (Newfoundland Appalachians):petrofacies, detrital clinopyroxene geochemistry and palaeotectonic implications. Precambrian Research, 59, 243-262.
17. DeGraaff-Surpless, K., Mahoney, J.B., Wooden, J.L. & McWilliams, M.O. 2003. Lithofacies control in detrital zircon provenance studies: Insights from the Cretaceous Methow basin, southern Canadian Cordillera. Geological Society of America Bulletin, 115, 899-915.
18. de Wit, M.J., Bowring, S., Dudas, F. & Kamga, G. 2005. The great Neoproterozoic central Saharan Arc and the amalgamation of the North African Shield. Geological Association of Canada, Annual Meeting, Abstracts with Programs, 30, 42-43.
19. Fedo, C.M., Sircombe, K.N. & Rainbird, R.H. 2003. Detrital zircon analysis of the sedimentary record. In: Hanchar, J.M. & Hoskin, P. (eds) Zircon: Experiments, Isotopes, and Trace Element Investigations. Mineralogical Society of America, Reviews in Mineralogy, 53, 277-303.
20. Fernacheckentity ́/checkentityndez-Suacheckentity ́/checkentityrez, J., Gutiecheckentity ́/checkentityrrez-Alonso, G. & Jeffries, T.E. 2002. The importance of along-margin terrane transport in northern Gondwana: Insights from detrital zircon parentage in Neoproterozoic rocks from Iberia and Brittany. Earth and Planetary Science Letters, 204, 75-88.
21. Fortey, R.A. & Cocks, L.R.M. 2003. Palaeontological evidence bearing on global Ordovician-Silurian continental reconstructions. Earth-Science Reviews, 61, 245-307.
22. Gower, C.F., Ryan, A.B. & Rivers, T. 1990. Mid-Proterozoic Laurentia-Baltica: an overview of its geological evolution and a summary of the contributions made by this volume. In: Gower, C.F., Rivers, T. & Ryan, A.B. (eds) MidProterozoic Laurentia-Baltica. Geological Association of Canada, Special Papers, 38, 1-20.
23. Greenough, J.G. & Papezik, V.S. 1986. Acado-Baltic volcanism in eastern North America and western Europe: Implications for Cambrian tectonism. Maritime Sediments and Atlantic Geology, 22, 240-251.
24. Hamilton, M.A. & Murphy, J.B. 2004. Tectonic significance of a Llanvirn age for the Dunn Point volcanic rocks, Avalon terrane, Nova Scotia, Canada: implications for the evolution of the Iapetus and Rheic Oceans. Tectonophysics, 379, 199-209.
25. Hibbard, J.P., van Staal, C.R. & Miller, B.V. 2007. Links between Carolinia, Avalonia, and Ganderia in the Appalachian peri-Gondwanan Realm. In: Sears, J.W., Harms, T.A. & Evenchick, C.A. (eds) Whence the Mountains?Inquiries into the Evolution of Orogenic Systems: A Volume in Honor of Raymond A. Price. Geological Society of America, Special Papers, 433, 291-311.
26. Hiscott, R.N. 1982. Tidal deposits of the Lower Cambrian Random Formation, eastern Newfoundland: facies and paleoenvironments. Canadian Journal of Earth Sciences, 19, 2028-2042.
27. Hodych, J.P. & Buchan, K.L. 1998. Palaeomagnetism of the c. 440 Ma Cape St Mary's sills of the Avalon Peninsula of Newfoundland: implications for Iapetus Ocean closure. Geophysical Journal International, 135, 155-164.
28. Hoffman, P.F. 1988. United Plates of America, the birth of a craton-Early Proterozoic assembly and growth of Laurentia. Annual Review of Earth and Planetary Sciences, 16, 543-603.
29. Hoffman, P.F. 1991. Did the breakout of Laurentia turn Gondwanaland inside out? Science, 252, 1409-1412.
30. Hughes, C.J. 1970. The Late Precambrian Avalonian Orogeny in Avalon, southeast Newfoundland. American Journal of Science, 269, 183-190.
31. Israel, S.A. 1998. Geochronological, structural and stratigraphic investigation of a Precambrian unconformity between the Harbour Main Group and Conception Group, east coast Holyrood Bay, Avalon Peninsula, Newfoundland. BSc(Hons) thesis, Memorial University of Newfoundland, St. John's.
32. 238U. Physical Review, C4, 1889-1906.
33. Jenness, S.E. 1963. Terra Nova and Bonavista map-areas, Newfoundland. Geological Survey of Canada Memoir, 327, 184.
34. Keppie, J.D., Nance, R.D., Murphy, J.B. & Dostal, J. 2002. Tethyan, Mediterranean, and Pacific analogues for the Neoproterozoic-Paleozoic birth and development of periondwanan terranes and their transfer to Laurentia and Laurussia. Tectonophysics, 365, 195-219.
35. Kerr, A., Jenner, G.A. & Fryer, B.J. 1995. Sm-Nd isotopic geochemistry of Precambrian to Paleozoic granitoid suites and the deep-crustal structure of the southeast margin of the Newfoundland Appalachians. Canadian Journal of Earth Sciences, 32, 224-245.
36. King, A.F. 1990. Geology of the St. John's area. Geological Survey Branch, Government of Newfoundland and Labrador, 90-2.
37. Kokelaar, P. 1988. Tectonic controls of Ordovician arc and marginal basin volcanism in Wales. Journal of the Geological Society, London, 145, 759-775.
38. Košler, J. & Sylvester, P. 2003. Present trends and the future of zircon in geochronology: laser ablation ICPMS. In: Hanchar, J.M. & Hoskin, P. (eds) Zircon: Experiments, Isotopes, and Trace Element Investigations. Mineralogical Society of America, Reviews in Mineralogy, 53, 243-275.
39. Košler, J., Forst, L. & Slacheckentity ́/checkentityma, J. 2008. LamDate and LamTool: spreadsheetbased data reduction for laser ablation ICP-MS. In: Sylvester, P.J. (ed.) Laser Ablation ICP-MS in the Earth Sciences: Current Practices and Outstanding Issues. Mineralogical Association of Canada, Short Courses, 40, 315-317.
40. Krogh, T.E. 1982. Improved accuracy of U-Pb zircon ages by the creation of a more concordant system using an air abrasion technique. Geochimica et Cosmochimica Acta, 46, 637-649.
41. Krogh, T.E., Strong, D.F., O'Brien, S.J. & Papezik, V. 1988. Precise U-Pb dates from zircons in the Avalon terrane of Newfoundland. Canadian Journal of Earth Sciences, 25, 442-453.
42. Landing, E. 1996. Avalon: Insular continent by the latest Precambrian. In: Nance, R.D. & Thompson, M.D. (eds) Avalonian and Related Peri-Gondwanan Terranes of the Circum-North Atlantic. Geological Society of America, Special Papers, 304, 29-63.
43. Landing, E. 2005. Early Paleozoic Avalon-Gondwana unity: an obituary-response to 'Palaeontological evidence bearing on global Ordovician-Silurian continental reconstructions' by R.A. Fortey and L.R.M. Cocks. Earth-Science Reviews, 69, 169-175.
44. Linnemann, U., Gerdes, A., Drost, K. & Buschmann, B. 2007. The continuum between Cadomian orogenesis and opening of the Rheic Ocean: Constraints from LA-ICP-MS U-Pb zircon dating and analysis of plate-tectonic setting (Saxo-Thuringian zone, northeastern Bohemian Massif, Germany). In: Linnemann, U., Nance, R.D., Kraft, P. & Zulauf, G. (eds) The Evolution of the Rheic Ocean: From Avalonian-Cadomian Active Margin to Alleghenian-Variscan Collision. Geological Society of America, Special Papers, 423, 61-96.
45. Ludwig, K.R. 2003. Isoplot/Ex 3: a Geochronological Toolkit for Microsoft Excel. Berkeley Geochronology Center Special Publication, 1a.
46. MacNiocaill, C. 2000. A new Silurian paleolatitude for eastern Avalonia and evidence for crustal rotations in the Avalonian margin of southwestern Ireland. Geophysical Journal International, 141, 661-671.
47. Mezger, K. & Krogstad, E.J. 1997. Interpretation of discordant U-Pb zircon ages, an evaluation. Journal of Metamorphic Geology, 15, 127-140.
48. Muller, R.D., Gaina, C., Roest, W.R. & Hansen, D.L. 2001. A recipe for microcontinent formation. Geology, 29, 203-206.
49. Murphy, J.B. & Nance R.D. 1989. A model for the evolution of the AvalonianCadomian belt. Geology, 17, 735-738.
50. Murphy, J.B., Keppie, J.D., Dostal, J. & Cousins, B.L. 1996. Repeated late Neoproterozoic-Silurian lower crustal melting beneath the Antigonish Highlands, Nova Scotia: Nd isotopic evidence and tectonic interpretations. In: Nance, R.D. & Thompson, M.D. (eds) Avalonian and Related PeriGondwanan Terranes of the Circum-North Atlantic. Geological Society of America, Special Papers, 304, 109-120.
51. Murphy, J.B., Keppie, J.D., Dostal, J. & Nance, R.D. 1999. Neoproterozoicearly Paleozoic evolution of Avalonia. In: Ramos, V.A. & Keppie, J.D. (eds) LaurentiaGondwana Connections Before Pangea. Geological Society of America, Special Papers, 336, 253-266.
52. Murphy, J.B., Fernandez-Suarez, J., Jeffries, T.E. & Strachan, R.A. 2004.U-Pb(LA-ICP-MS)datingofdetritalzirconsfromCambrianclasticrocksin Avalonia: erosion of a Neoproterozoic arc along the northern Gondwanan margin. Journal of the Geological Society, London, 161, 243-254.
53. Murphy, J.B., Gutierrez-Alonso, G., Nance, R.D., et al. 2006. Origin of the Rheic Ocean: Rifting along a Neoproterozoic suture? Geology, 34, 325-328.
54. Murphy, J.B., McCausland, P.J.A., O'Brien, S.J., Pisarevski, S. & Hamilton, M.A. 2008. Age, geochemistry and Sm-Nd isotopic signature of the 0.76 Ga Burin Group: Compositional equivalent of Avalonian basement? Precambrian Research, 165, 37-48.
55. Myrow, P.M. & Hiscott, R.N. 1993. Depositional history and sequence stratigraphy of the Precambrian-Cambrian boundary stratotype section, Chapel Island Formation, southeast Newfoundland. Paleogeography, Paleoclimatology, Paleoecology, 104, 13-35.
56. Myrow, P.M. & Kaufman, A.J. 1999. A newly discovered cap carbonate above Varangerage glacial deposits in Newfoundland, Canada. Journal of Sedimentary Research, 69, 784-793.
57. Nance, R.D., Murphy, J.B. & Keppie, J.D. 2002. A Cordilleran model for the evolution of Avalonia. Tectonophysics, 352, 11-31.
58. Narbonne, G.M. & Gehling, J.G. 2003. Life after snowball: the oldest complex Ediacaran fossils. Geology, 31, 27-30.
59. O'Brien, S.J. & King, A.F. 2005. Late Neoproterozoic (Ediacaran) stratigraphy of Avalon Zone sedimentary rocks, Bonavista Peninsula, Newfoundland. Current Research, Government of Newfoundland and Labrador, Department of Mines and Energy, Geological Survey, 06-1, 101-114.
60. O'Brien, S.J., O'Driscoll, C.F., Greene, B.A. & Tucker, R.D. 1995. PreCarboniferous geology of the Connaigre Peninsula and the adjacent coast of Fortune Bay, southern Newfoundland. Current Research, Government of Newfoundland and Labrador, Department of Mines and Energy, Geological Survey, 95-1, 267-298.
61. O'Brien, S.J., O'Brien, B.H., Dunning, G.R. & Tucker, R.D. 1996. Late Neoproterozoic Avalonian and related peri-Gondwanan rocks of the Newfoundland Appalachians In: Nance, R.D. & Thompson, M.D. (eds) Avalonian and Related PeriGondwanan Terranes of the Circum-North Atlantic. Geological Society of America, Special Papers, 304, 9-28.
62. O'Brien, S.J., Dunning, G.R., Dube, B., O'Driscoll, C.F., Sparkes, B., Israel, S. & Ketchum, J. 2001. New insights into the Neoproterozoic geology of the central Avalon Peninsula (parts of NTS map areas 1N/6, 1N/7 and 1N/3), eastern Newfoundland. Current Research, Government of Newfoundland and Labrador, Department of Mines and Energy, Geological Survey, 2001-1, 169-189.
63. Pollock, J.C. 2007. The Neoproterozoic-Early Paleozoic tectonic evolution of the periGondwanan margin of the Appalachian orogen: an integrated geochronological, geochemical and isotopic study from North Carolina and Newfoundland. PhD thesis, North Carolina State University, Raleigh.
64. Pollock, J.C., Wilton, D.H.C., van Staal, C.R. & Morrissey, K.D. 2007. U-Pb detrital zircon geochronological constraints on the Early Silurian collision of Ganderia and Laurentia along the Dog Bay Line: The terminal Iapetan suture in the Newfoundland Appalachians. American Journal of Science, 307, 399-433.
65. 18O-depletion of Neoproterozoic igneous rocks from Avalonia, Cape Breton Island and southern New Brunswick, Canada. Geological Society of America Bulletin, 120,347-367.
66. Prigmore, J.K., Butler, A.J. & Woodcock, N.H. 1997. Rifting during separation of eastern Avalonia from Gondwana; evidence from subsidence analysis. Geology, 25, 203-206.
67. Ranger, M.J., Pickerill, R.K. & Fillion, D. 1984. Lithostratigraphy of the Cambrian?-Lower Ordovician Bell Island and Wabana groups of Bell, Little Bell, and Kellys islands, Conception Bay, eastern Newfoundland. Canadian Journal of Earth Sciences, 21, 1245-1261.
68. Rice, T.G. 1996. Structure of the Flat Rock thrust zone, Avalon Peninsula, Newfoundland Appalachians. BSc(Hons) thesis, Memorial University of Newfoundland, St. John's.
69. Rocci, G., Bronner, G. & Deschamps, M. 1991. Crystalline basement of the West African craton. In: Dallmeyer, R.D. & Lecorche, J.P. (eds) The West African Orogens and CircumAtlantic Correlatives. Springer, Heidelberg, 31-61.
70. Sadowski, G.R. & Bettencourt, J.S. 1996. Mesoproterozoic tectonic correlations between eastern Laurentia and the western border of the Amazon craton. Precambrian Research, 76, 213-227.
71. Samson, S.D. & D'Lemos, R.S. 1998. U-Pb geochronology and Sm-Nd isotopic composition of Proterozoic gneisses, Channel Islands, UK. Journal of the Geological Society, London, 155, 609-618.
72. Samson, S.D., D'Lemos, R.S., Miller, B.V. & Hamilton, M.A. 2005. Neoproterozoic palaeogeography of the Cadomia and Avalon terranes: constraints from detrital zircon U-Pb ages. Journal of the Geological Society, London, 162, 65-71 http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V5Y-454TGNB-X&_user=809099&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000043939&_version=1&_url=0&_userid=809099&md5=2d91a999423302090bed1dff9b7b3e8f - bbib40#bbib40.
73. Shinjo, R., Chung, S.L., Kato, Y. & Kimura, M. 1999. Geochemical and Sr-Nd isotopic characteristics of volcanic rocks from the Okinawa Trough and Ryukyu Arc: implications for the evolution of a young, intracontinental back arc basin. Journal of Geophysical Research, 104, 10591-10608.
74. Sircombe, K.N. & Stern, R.A. 2002. An investigation of artificial biasing in detrital Zircon U-Pb geochronology due to magnetic separation in sample preparation. Geochimica Et Cosmochimica Acta, 66, 2379-2397.
75. Sircombe, K., Bleeker, W. & Stern, R. 2001. Detrital zircon geochronology and grain-size analysis of a,2800 Ma Mesoarchean proto-cratonic cover succession, Slave Province, Canada. Earth and Planetary Science Letters, 189, 207-220.
76. Sláma, J.,Košler, J., Condon, D.J., et al. 2008. Plešovice zircon-a new natural reference material for U-Pb and Hf isotopic microanalysis. Chemical Geology, 249, 1-35.
77. Sloss, L.L. 1963. Sequences in the cratonic interior of North America. Geological Society of America Bulletin, 74, 93-114.
78. Stampfli, G.D. & Borel, G.D. 2002. A plate tectonic model for the Paleozoic and Mesozoic constrained by dynamic plate boundaries and restored synthetic oceanic isochrones. Earth and Planetary Science Letters, 196, 17-33.
79. Strong, D.F. & Dostal, J. 1980. Dynamic melting of Proterozoic upper mantle: Evidence from rare earth elements in oceanic crust of Eastern Newfoundland. Contributions to Mineralogy and Petrology, 72, 165-173.
80. Swinden, H.S. & Hunt, P.A. 1991. A U-Pb zircon age from the Connaigre Bay Group, southwestern Avalon Zone, Newfoundland: Implications for regional correlations and metallogenesis. In: Radiometric Age and Isotopic Studies, Report 4. Geological Survey of Canada, 90-2, 3-10.
81. Sylvester, P.J. & Ghaderi, M. 1997. Trace element analysis of scheelite by excimer laser ablation-inductively coupled plasma-mass spectrometry (ELA-ICP-MS) using a synthetic glass standard. Chemical Geology, 141, 49-65.
82. Thompson, M.D. & Bowring, S.A. 2000. Age of the Squantum 'tillite', Boston Basin, Massachusetts: U-Pb zircon constraints on terminal Neoproterozoic glaciation. American Journal of Science, 300, 630-655.
83. Torsvik, T.H., Smethurst, M.A., Meert, J.G., et al. 1996. Continental break-up and collision in the Neoproterozoic-a tale of Baltica and Laurentia. Earth-Science Reviews, 40, 229-258.
84. van der Voo, R. & Johnson, R.J.E. 1985. Paleomagnetism of the Dunn Point Formation (Nova Scotia): high paleolatitudes for the Avalon terrane in the Late Ordovician. Geophysical Research Letters, 12, 337-340.
85. van Ingen, G. 1914. Cambrian and Ordovician faunas of south-eastern Newfoundland. Geological Society of America Bulletin, 25, 138.
86. van Staal, C.R. 2007. Pre-Carboniferous tectonic evolution and metallogeny of the Canadian Appalachians. In: Goodfellow, W.D. (ed.) Mineral Deposits of Canada: A Synthesis of Major Deposit Types, District Metallogeny, the Evolution of Geological Provinces & Exploration Methods. Geological Association of Canada, Mineral Deposits Division, Special Publication, 5, 793-817.
87. van Staal, C.R., Dewey, J.F., MacNiocaill, C. & McKerrow, W.S. 1998. The Cambrian-Silurian tectonic evolution of the northern Appalachians and British Caledonides: history of a complex west and southwest Pacific-type segment of Iapetus. In: Blundell, D.J. & Scott, A.C. (eds) Lyell: The Past is the Key to the Present. Geological Society, London, Special Publications, 143,199-242.
88. Vermeesch, P. 2004. How many grains are needed for a provenance study? Earth and Planetary Science Letters, 224, 441-451.
89. Walcott, C.D. 1900. Random-Precambrian Upper Algonkian terrane. Geological Society of America Bulletin, 11, 3-5.
90. Waldron, J.F. & van Staal., C.R. 2001 Taconian orogeny and the accretion of the Dashwoods block: A peri-Laurentian microcontinent in the Iapetus Ocean. Geology, 29, 811-814.
91. Wardle, R.J., Gower, C.F., James, D.T., et al. 2002. Correlation chart of the Proterozoic assembly of the northeastern Canadian-Greenland Shield. Canadian Journal of Earth Sciences, 39, 895.
92. Wiedenbeck, M., Allé, P., et al. 1995. Three natural zircon standards for U-Th-Pb, Lu-Hf, trace element and REE analysis. Geostandards Newsletters, 19,1-23.
93. Williams, H. 1964. The Appalachians in northeastern Newfoundland-a two-sided symmetrical system. American Journal of Science, 262, 1137-1158.
94. Williams, H. 1984. Miogeoclines and suspect terranes of the CaledonianAppalachian Orogen: tectonic patterns in the North Atlantic region. Canadian Journal of Earth Sciences, 21, 887-901.
95. Williams, H. & Hiscott, R.N. 1987. Definition of the Iapetus rift-drift transition in western Newfoundland. Geology, 15, 1044-1047.
96. Williams, H. & King, A.F. 1979. Trepassey Map Area, Newfoundland. Geological Survey of Canada Memoir, 389.
97. Williams, H., O'Brien, S.J., King, A.F. & Anderson, M.M. 1995. Avalon zone-Newfoundland. In: Williams, H. (ed.) Geology of the AppalachianCaledonian Orogen in Canada and Greenland. Geology of North America, F-1, 226-237.
98. Zartman, O. & Hermes, D. 1987. Archean inheritance in zircon from late Paleozoic granites from the Avalon zone of southeastern New England: an African connection. Earth and Planetary Science Letters, 82, 305-315.