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Nain Province

January 01, 1970

In Labrador, Canada, the North Atlantic Craton is known as the Nain Province. The Nain geologic province was intruded by the Nain Plutonic Suite, which divides the province into the northern Saglek block and the southern Hopedale block.[1]

Note Saglek Bay, Nain and Hopedale

North Atlantic Craton edit

The North Atlantic Craton is exposed in parts of the coast of Labrador, parts of central Greenland, the Scourian Complex of northwestern Scotland and is unexposed in northern Norway. The North Atlantic Craton fragmented 2450 to 2000 million years ago.[2]: 847  When North America and Europe rejoined, the North Atlantic Craton was triangular shaped with each side 600 km (370 mi); this unit was separated when the Labrador Sea formed 61 to 40 million years ago. The crust of the North Atlantic Craton varies between 28 and 38 km (17 and 24 mi) thick[3]: 673  and its rocks are 85% granitoid gneisses. The Nain Province was intruded by the 1350- to 1290-million-year-old Nain Plutonic Suite;[3]: 673  composite anorthosite-granitic intrusions which divide the Nain Province into the northern Saglek Block and the southern Hopedale Block.[1]

Nain Province edit

In Labrador, the North Atlantic Craton is known as the Nain Province or Nain Craton. The Nain Province is more than 600 km (370 mi) long and 100 km (62 mi) wide.[1] The gneisses of the Nain Province were last deformed and metamorphosed[4]: 1245  when two blocks docked together 2500 million years ago[5] with a collisional boundary extending 200 km (120 mi) to the north and 150 km (93 mi) to the south of Nain, Labrador, Canada.[6] These two blocks appear to represent two distinct Archean cratonic nuclei, each with its own mineral depositional history.[1] Major granitic intrusions – the Wheeler Mountain, Halbach, Alliger, Sheet Hill, Loon Island, Red Island, and Satok Island intrusions – form a north-trending 150 km (93 mi) linear chain which have a southerly decrease in age – 2135-million-year-old Wheeler Mountain granite in the north to the 2025-million-year-old Satok Island monzonite in the south.[2]: 847, 848  The Nain Province was then intruded by the 1350- to 1290-million-year-old Nain Plutonic Suite;[3]: 673  composite anorthosite-granitic intrusions which divide the Nain Province into the northern Saglek block and the southern Hopedale block.[1] The Torngat orogen developed during the oblique convergence of the Superior and Nain Provinces[7]: 23, 403  900 million years ago. The crystalline crust in the Nain Province is 38 km (24 mi) thick; it thins to 9 km (5.6 mi) thick in the shelf area of the Labrador margin, where it is covered with up to 8 km (5.0 mi) of sediments.[8]

Saglek block edit

The 3800- to 3300-million-year-old Saglek block[5] is 375 km (233 mi) long and 50 km (31 mi) wide;[1] it has a north-northwesterly trend from Nain, Labrador, extending nearly to the northern tip of Labrador. This block is a high-grade gneiss terrane; it has no greenstone belts.[1] Within the gneiss are variably-sized enclaves ranging from anorthosite to ultramafic.[1] There are also three small anorthositic, ultramafic meta-igneous complexes in the gneiss near Okak Bay.[1]

The northward–trending Handy fault separates the Saglek block into two metamorphic parts.[3]: 673  The gneiss complex on the western side of the Handy fault has rocks that crystallized under granulite facies conditions; this western block is more deeply exposed than the eastern one.[3]: 681  On the eastern side amphibolite facies rocks are exposed in the northern part; they transition to granulite facies to the south.[3]: 673  The total crustal thickness is 33 km (21 mi) north of the fault and 38 km (24 mi) south of the fault.[9]

Hopedale block edit

 
Hunt River and Florence Lake greenstone belts

The 3100- to 2800-million-year-old Hopedale block[5] is 150 km (93 mi) long and 90 km (56 mi) wide.[1] Hopedale, Labrador, is at the eastern midpoint. This block contains the 3100-million-year-old[10] Hunt River and 3000-million-year-old Florence Lake greenstone belts, and the Weekes amphibolite which represents remnants of the older Hunt River greenstone belt.[1]

References edit

  1. ^ a b c d e f g h i j k Wilton, D. H. C. (1996). "Metallogenic Overview of the Nain Province, Northern Labrador". CIM Bulletin. 89 (99). Canadian Institute of Mining, Metallurgy and Petroleum, Montréal, PQ, Canada: 43. ISSN 0317-0926. Retrieved June 24, 2010.
  2. ^ a b Connelly, James N.; Ryan, A. Bruce (1999). "Age and Tectonic Implications of Paleoproterozoic Granitoid Intrusions Within the Nain Province near Nain, Labrador". Canadian Journal of Earth Sciences. 36 (5): 833–853. Bibcode:1999CaJES..36..833C. doi:10.1139/cjes-36-5-833. Archived from the original on December 16, 2012. Retrieved June 13, 2010.
  3. ^ a b c d e f Funck, Thomas Funck; Louden, Keith E. (1998). "Wide-Angle Seismic Imaging of Pristine Archean Crust in the Nain Province, Labrador". Canadian Journal of Earth Sciences. 35 (6): 672–685. Bibcode:1998CaJES..35..672F. doi:10.1139/cjes-35-6-672. Archived from the original on 2012-12-16. Retrieved June 13, 2010.
  4. ^ Culshaw, N.; Brown, T.; Reynolds, P.H.; Ketchum, J.W.F. (2000). "Kanairiktok Shear Zone: The Boundary Between the Paleoproterozoic Makkovik Province and the Archean Nain Province, Labrador, Canada". Canadian Journal of Earth Sciences. 37 (9): 1245–1257. Bibcode:2000CaJES..37.1245C. doi:10.1139/cjes-37-9-1245. Retrieved June 12, 2010.[permanent dead link]
  5. ^ a b c Mareschal, J.C.; Poirier, A.; Rolandone, F.; Bienfait, G.; et al. (March 15, 2000). "Low mantle heat flow at the edge of the North American continent, Voisey Bay, Labrador" (PDF). Geophysical Research Letters. 27 (6): 823–826. Bibcode:2000GeoRL..27..823M. doi:10.1029/1999GL011069. Retrieved June 12, 2010.
  6. ^ Connelly, J.N.; Ryan, B. (1996). "Late Archean evolution of the Nain Province, Nain, Labrador: imprint of a collision". Canadian Journal of Earth Sciences. 33 (9): 1325–1342. Bibcode:1996CaJES..33.1325C. doi:10.1139/e96-100. Retrieved June 13, 2010.[permanent dead link]
  7. ^ Funck, Thomas; Louden, Keith E.; Wardle, Richard J.; Hall, Jeremy; Hobro, James W.; Salisbury, Matthew H.; Muzzatti, Angelina M. (2000). "Three-Dimensional Structure of the Torngat Orogen (NE Canada) from Active Seismic Tomography". Journal of Geophysical Research. 105 (B10): 23, 403–23, 420. Bibcode:2000JGR...10523403F. doi:10.1029/2000JB900228. Retrieved June 13, 2010.
  8. ^ Funck, Thomas; Louden, Keith E. (1999). "Wide-angle Seismic Transect Across the Torngat Orogen, Northern Labrador: Evidence for a Proterozoic Crustal Root". Journal of Geophysical Research. 104 (B4): 7463. Bibcode:1999JGR...104.7463F. doi:10.1029/1999jb900010. Retrieved June 13, 2010.
  9. ^ Funck, Thomas; Louden, Keith E. (1998). "Wide-Angle Seismic Imaging of Pristine Archean Crust in the Nain Province, Labrador". Canadian Journal of Earth Sciences. 35 (6): 672–685. Bibcode:1998CaJES..35..672F. doi:10.1139/cjes-35-6-672. Retrieved June 20, 2010.[permanent dead link]
  10. ^ James, D.T.; Kamo, S.; Krogh, T. (2002). "Evolution of 3.1 and 3.0 Ga Volcanic Belts and a New Thermotectonic Model for the Hopedale Block, North Atlantic Craton (Canada)". Canadian Journal of Earth Sciences. 39 (5): 687–710. Bibcode:2002CaJES..39..687J. doi:10.1139/e01-092. Retrieved June 30, 2010.[permanent dead link]

56°35′N 62°04′W / 56.58°N 62.06°W / 56.58; -62.06

January 01, 1970
nain, province, labrador, canada, north, atlantic, craton, known, nain, geologic, province, intruded, nain, plutonic, suite, which, divides, province, into, northern, saglek, block, southern, hopedale, block, note, saglek, nain, hopedale, contents, north, atla. In Labrador Canada the North Atlantic Craton is known as the Nain Province The Nain geologic province was intruded by the Nain Plutonic Suite which divides the province into the northern Saglek block and the southern Hopedale block 1 Note Saglek Bay Nain and Hopedale Contents 1 North Atlantic Craton 2 Nain Province 3 Saglek block 4 Hopedale block 5 ReferencesNorth Atlantic Craton editThe North Atlantic Craton is exposed in parts of the coast of Labrador parts of central Greenland the Scourian Complex of northwestern Scotland and is unexposed in northern Norway The North Atlantic Craton fragmented 2450 to 2000 million years ago 2 847 When North America and Europe rejoined the North Atlantic Craton was triangular shaped with each side 600 km 370 mi this unit was separated when the Labrador Sea formed 61 to 40 million years ago The crust of the North Atlantic Craton varies between 28 and 38 km 17 and 24 mi thick 3 673 and its rocks are 85 granitoid gneisses The Nain Province was intruded by the 1350 to 1290 million year old Nain Plutonic Suite 3 673 composite anorthosite granitic intrusions which divide the Nain Province into the northern Saglek Block and the southern Hopedale Block 1 Nain Province editIn Labrador the North Atlantic Craton is known as the Nain Province or Nain Craton The Nain Province is more than 600 km 370 mi long and 100 km 62 mi wide 1 The gneisses of the Nain Province were last deformed and metamorphosed 4 1245 when two blocks docked together 2500 million years ago 5 with a collisional boundary extending 200 km 120 mi to the north and 150 km 93 mi to the south of Nain Labrador Canada 6 These two blocks appear to represent two distinct Archean cratonic nuclei each with its own mineral depositional history 1 Major granitic intrusions the Wheeler Mountain Halbach Alliger Sheet Hill Loon Island Red Island and Satok Island intrusions form a north trending 150 km 93 mi linear chain which have a southerly decrease in age 2135 million year old Wheeler Mountain granite in the north to the 2025 million year old Satok Island monzonite in the south 2 847 848 The Nain Province was then intruded by the 1350 to 1290 million year old Nain Plutonic Suite 3 673 composite anorthosite granitic intrusions which divide the Nain Province into the northern Saglek block and the southern Hopedale block 1 The Torngat orogen developed during the oblique convergence of the Superior and Nain Provinces 7 23 403 900 million years ago The crystalline crust in the Nain Province is 38 km 24 mi thick it thins to 9 km 5 6 mi thick in the shelf area of the Labrador margin where it is covered with up to 8 km 5 0 mi of sediments 8 Saglek block editThe 3800 to 3300 million year old Saglek block 5 is 375 km 233 mi long and 50 km 31 mi wide 1 it has a north northwesterly trend from Nain Labrador extending nearly to the northern tip of Labrador This block is a high grade gneiss terrane it has no greenstone belts 1 Within the gneiss are variably sized enclaves ranging from anorthosite to ultramafic 1 There are also three small anorthositic ultramafic meta igneous complexes in the gneiss near Okak Bay 1 The northward trending Handy fault separates the Saglek block into two metamorphic parts 3 673 The gneiss complex on the western side of the Handy fault has rocks that crystallized under granulite facies conditions this western block is more deeply exposed than the eastern one 3 681 On the eastern side amphibolite facies rocks are exposed in the northern part they transition to granulite facies to the south 3 673 The total crustal thickness is 33 km 21 mi north of the fault and 38 km 24 mi south of the fault 9 Hopedale block edit nbsp Hunt River and Florence Lake greenstone belts The 3100 to 2800 million year old Hopedale block 5 is 150 km 93 mi long and 90 km 56 mi wide 1 Hopedale Labrador is at the eastern midpoint This block contains the 3100 million year old 10 Hunt River and 3000 million year old Florence Lake greenstone belts and the Weekes amphibolite which represents remnants of the older Hunt River greenstone belt 1 References edit a b c d e f g h i j k Wilton D H C 1996 Metallogenic Overview of the Nain Province Northern Labrador CIM Bulletin 89 99 Canadian Institute of Mining Metallurgy and Petroleum Montreal PQ Canada 43 ISSN 0317 0926 Retrieved June 24 2010 a b Connelly James N Ryan A Bruce 1999 Age and Tectonic Implications of Paleoproterozoic Granitoid Intrusions Within the Nain Province near Nain Labrador Canadian Journal of Earth Sciences 36 5 833 853 Bibcode 1999CaJES 36 833C doi 10 1139 cjes 36 5 833 Archived from the original on December 16 2012 Retrieved June 13 2010 a b c d e f Funck Thomas Funck Louden Keith E 1998 Wide Angle Seismic Imaging of Pristine Archean Crust in the Nain Province Labrador Canadian Journal of Earth Sciences 35 6 672 685 Bibcode 1998CaJES 35 672F doi 10 1139 cjes 35 6 672 Archived from the original on 2012 12 16 Retrieved June 13 2010 Culshaw N Brown T Reynolds P H Ketchum J W F 2000 Kanairiktok Shear Zone The Boundary Between the Paleoproterozoic Makkovik Province and the Archean Nain Province Labrador Canada Canadian Journal of Earth Sciences 37 9 1245 1257 Bibcode 2000CaJES 37 1245C doi 10 1139 cjes 37 9 1245 Retrieved June 12 2010 permanent dead link a b c Mareschal J C Poirier A Rolandone F Bienfait G et al March 15 2000 Low mantle heat flow at the edge of the North American continent Voisey Bay Labrador PDF Geophysical Research Letters 27 6 823 826 Bibcode 2000GeoRL 27 823M doi 10 1029 1999GL011069 Retrieved June 12 2010 Connelly J N Ryan B 1996 Late Archean evolution of the Nain Province Nain Labrador imprint of a collision Canadian Journal of Earth Sciences 33 9 1325 1342 Bibcode 1996CaJES 33 1325C doi 10 1139 e96 100 Retrieved June 13 2010 permanent dead link Funck Thomas Louden Keith E Wardle Richard J Hall Jeremy Hobro James W Salisbury Matthew H Muzzatti Angelina M 2000 Three Dimensional Structure of the Torngat Orogen NE Canada from Active Seismic Tomography Journal of Geophysical Research 105 B10 23 403 23 420 Bibcode 2000JGR 10523403F doi 10 1029 2000JB900228 Retrieved June 13 2010 Funck Thomas Louden Keith E 1999 Wide angle Seismic Transect Across the Torngat Orogen Northern Labrador Evidence for a Proterozoic Crustal Root Journal of Geophysical Research 104 B4 7463 Bibcode 1999JGR 104 7463F doi 10 1029 1999jb900010 Retrieved June 13 2010 Funck Thomas Louden Keith E 1998 Wide Angle Seismic Imaging of Pristine Archean Crust in the Nain Province Labrador Canadian Journal of Earth Sciences 35 6 672 685 Bibcode 1998CaJES 35 672F doi 10 1139 cjes 35 6 672 Retrieved June 20 2010 permanent dead link James D T Kamo S Krogh T 2002 Evolution of 3 1 and 3 0 Ga Volcanic Belts and a New Thermotectonic Model for the Hopedale Block North Atlantic Craton Canada Canadian Journal of Earth Sciences 39 5 687 710 Bibcode 2002CaJES 39 687J doi 10 1139 e01 092 Retrieved June 30 2010 permanent dead link 56 35 N 62 04 W 56 58 N 62 06 W 56 58 62 06 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