North Atlantic Igneous Province

The North Atlantic Igneous Province (NAIP) is a large igneous province estimated to be at least 1.3×106 km2 in area and 6.6×106 km3 in volume.[1] Geographically, the NAIP makes up all of the North Atlantic Ocean as well as the Paleocene and Eocene basalts of Greenland, Iceland, the United Kingdom, Denmark, Norway and many of the islands located in the north eastern portion of the North Atlantic ocean.[2][3]

Isotopic dating indicates the most active magmatic phase of the NAIP was between ca. 60.5 and ca. 54.5 Ma (million years ago)[4] (mid-Paleocene to early Eocene) - further divided into Phase 1 (pre-break-up phase) dated to ca. 62-58 Ma and Phase 2 (syn-break-up phase) dated to ca. 56-54 Ma.[5]

Continuing research also indicates that continental plate movement (Eurasian, Greenland, and North American), that regional rifting events, and that seafloor spreading between Labrador and Greenland may have begun as early as ca. 95-80 Ma,[6] ca. 81 Ma,[7] and ca. 63-61 Ma[8][9] respectively (late Cretaceous to early Paleocene).

The formation of the NAIP has also been linked to the Iceland hotspot / mantle plume. Through both geochemical observations and reconstructions of paleogeography, it is speculated that the present day Iceland hotspot originated as a mantle plume on the Alpha Ridge (Arctic Ocean) ca. 130-120 Ma,[10] migrated down Ellesmere Island, through Baffin Island, onto the west coast of Greenland, and finally arrived on the east coast of Greenland by ca. 60 Ma.[11]

The present-day Iceland and Jan Mayen hotspots and North Atlantic Ridge are still geologically active.

The NAIP is made up of both onshore and offshore basalt floods, sills, dykes, and plateaus. Dependent upon various regional locations, the NAIP is made up of MORB (Mid Ocean Ridge Basalt), alkali basalt,[12][13] tholeiitic basalt, and picrite basalt.[14]

Synonymous or related names

See also

References

  1. ↑ Eldholm, Olav; Kjersti Grue (10 February 1994). "North Atlantic volcanic margins: Dimensions and production rates". Journal of Geophysical Research: Solid Earth 99 (B2): 2955–2968. doi:10.1029/93JB02879. Quantitative calculations of NAVP dimensions, considered minimum estimates, reveal an areal extent of 1.3{{e|6}} km2 and a volume of flood basalts of 1.8×106 km3, yielding a mean eruption rate of 0.6 km3/yr or 2.4 km3/yr if two-thirds of the basalts were emplaced within 0.5 m.y. The total crustal volume is 6.6×106 km3, resulting in a mean crustal accretion rate of 2.2 km3/yr. Thus NAVP ranks among the world's larger igneous provinces if the volcanic margins are considered.
  2. ↑ D.W. Jolley, B.R. Bell, ed. (2002). The North Atlantic igneous province stratigraphy, tectonic, volcanic, and magmatic processes. London: Geological Society. ISBN 1-86239-108-4.
  3. ↑ Courtillot, Vincent E; Renne, Paul R (January 2003). "On the ages of flood basalt events" (PDF). Comptes Rendus Geoscience 335 (1): 113–140. doi:10.1016/S1631-0713(03)00006-3. From file page 7 onward: Brito-Arctic Province section (section also discusses age, pulses of activity, and volume)
  4. ↑ Jolley, D. W.; Bell, B. R. (1 January 2002). "The evolution of the North Atlantic Igneous Province and the opening of the NE Atlantic rift". Geological Society, London, Special Publications 197 (1): 1–13. doi:10.1144/GSL.SP.2002.197.01.01. 40Ar/39Ar and Pb-U isotopic age data show that the main period of continental flood basalt volcanism in the NAIP extended from ~60.5 Ma through to ~54.5 Ma.
  5. ↑ Rousse, S.; M. Ganerød, M.A. Smethurst, T.H. Torsvik, T. Prestvik (2007). "The British Tertiary Volcanics: Origin, History and New Paleogeographic Constraints for the North Atlantic" (PDF). Geophysical Research Abstracts 9. The NAIP formed during two major magmatic phases: a pre-break-up phase (62-58 Ma) and a syn-break-up phase (56-54 Ma) contemporaneous with the onset of North Atlantic sea floor spreading.
  6. ↑ Torsvik, T.H.; B. Steinberger; C. Gaina (2007). "North Atlantic Plate Motions and Plumes" (PDF). Geophysical Research Abstracts 9. Fixed hotspot frames show uniform NE movement of the coupled North American, Greenland, and Eurasian plates from ~95 to 80 Ma.
  7. ↑ Faleide, Jan Inge; Tsikalas, F., Breivik, A. J., Mjelde, R., Ritzmann, O., Engen, O., Wilson, & Eldholm, O. (2008). "Structure and evolution of the continental margin off Norway and the Barents Sea" (PDF). Episodes 31 (1): 82. Breakup in the NE Atlantic was preceded by prominent Late Cretaceous-Paleocene rifting. At the onset of this rifting, the area between NW Europe and Greenland was an epicontinental sea covering a region in which the crust had been extensively weakened by previous rift episodes. Ren et al. (2003) suggested onset of rifting at about 81 Ma
  8. ↑ Larsen, Lotte Melchior; Rex, D. C.; Watt, W. S.; Guise, P. G. (1999). "40Ar/39Ar Dating of Alkali Basaltic Dykes along the Southwest Coast of Greenland: Cretaceous and Tertiary Igneous Activity along the Eastern Margin of the Labrador Sea" (PDF). Geology of Greenland Survey Bulletin (184): 19–29. The start of normal velocity ocean floor spreading in the Labrador Sea took place in the Paleocene, around geomagnetic chrons C27-C28 (61-63 Ma) and was accompanied by a burst in volcanic activity, where large amounts of tholeiitic picrites and basalts were erupted onto the continental margins of West Greenland and Labrador
  9. ↑ Chalmers, J. A.; Pulvertaft, T.C.R. (1 January 2001). "Development of the continental margins of the Labrador Sea: a review". Geological Society, London, Special Publications 187 (1): 77–105. doi:10.1144/GSL.SP.2001.187.01.05. The Labrador Sea is a small oceanic basin that developed when the North American and Greenland plates separated. An initial period of stretching in Early Cretaceous time formed sedimentary basins now preserved under the continental shelves and around the margins of the oceanic crust. The basins subsided thermally during Late Cretaceous time and a second episode of tectonism took place during latest Cretaceous and early Paleocene time, before the onset of sea-floor spreading in mid-Paleocene time.
  10. ↑ Saunders, A.D.; S. Drachev, M.K. Reichow (2005). "Tracking the Iceland Plume across the Arctic Ocean" (PDF). Geophysical Research Abstracts 7. It is widely assumed that Iceland sits above a mantle plume or hotspot. This plume has been tracked back to about 60 Ma, when it resided beneath Greenland. We explore the alternative possibility that the plume existed long before 60 Ma and was responsible for volcanic activity in northern Canada, beneath the Arctic Ocean, and across the Barents Shelf and in Siberia. Plate reconstructions place the plume beneath what is now northeastern Canada at about 80 Ma. This correlates with an episode of basaltic volcanism in the Queen Elizabeth Islands, dated at around 90 Ma. The aseismic Alpha Ridge is bathymetrically linked to northern Ellesmere Island, and extends northwards beneath the Arctic Ocean.
  11. ↑ Tegner, C; Duncan, R; Bernstein, S; Brooks, C; Bird, D; Storey, M (15 March 1998). "40Ar/39Ar geochronology of Tertiary mafic intrusions along the East Greenland rifted margin: Relation to flood basalts and the Iceland hotspot track". Earth and Planetary Science Letters 156 (1-2): 75–88. doi:10.1016/S0012-821X(97)00206-9. The East Greenland Tertiary Igneous Province includes the largest exposed continental flood basalt sequence within the North Atlantic borderlands. Plate-kinematic models indicate the axis of the ancestral Iceland mantle plume was located under Central Greenland at ~60 Ma and subsequently crossed the East Greenland rifted continental margin.
  12. ↑ Tarney, J.; Wood, D. A.; Saunders, A. D.; Cann, J. R.; Varet, J. (24 July 1980). "Nature of Mantle Heterogeneity in the North Atlantic: Evidence from Deep Sea Drilling". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 297 (1431): 179–202. doi:10.1098/rsta.1980.0209. Studies of dredged and drilled samples from the North Atlantic ocean have revealed that basalts with a wide range of major and trace element compositions have been generated at the Mid-Atlantic Ridge. Drilling along mantle flow lines transverse to the ridge has shown that different segments of the MAR have produced basalts with a distinct compositional range for tens of millions of years.
  13. ↑ Heister, L. E.; O'Day, P. A.; Brooks, C. K.; Neuhoff, P. S.; Bird, D. K. (1 March 2001). "Pyroclastic deposits within the East Greenland Tertiary flood basalts". Journal of the Geological Society 158 (2): 269–284. doi:10.1144/jgs.158.2.269. Stratigraphic, geochemical and mineralogical characterization of pyroclastic deposits on the Gronau West Nunatak of East Greenland indicates that both alkaline and basaltic tephras occurred during the eruption of flood basalts associated with the opening of the North Atlantic ocean in the early Tertiary.
  14. ↑ Brooks, C. K.; Nielsen, T. F. D.; Petersen, T. S. (1976). "The Blosseville Coast basalts of East Greenland: Their occurrence, composition and temporal variations". Contributions to Mineralogy and Petrology 58 (3): 279–292. doi:10.1007/BF00402356. Major and trace element compositions are presented for basalts from the area between Kangerdlugssuaq and Scoresby Sund, East Greenland. The bulk of these lavas have a very uniform composition and are tholeiites... The only significant variation is minor and represents a change to a more evolved type to the south, a variation which may be similar to that observed in Postglacial Icelandic lavas. The earliest lavas are of a picritic type…

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