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

• Brito-Arctic province (BAP)
• North Atlantic Tertiary Province (NATP)
• North Atlantic Volcanic Province (NAVP)
• North Atlantic Basalt Province (NABP)
• North Atlantic Tertiary Volcanic Province (NATVP)
• British Tertiary Igneous Province (BTIP)
• British Tertiary Volcanic Province (BTVP)
• British Paleogene Igneous Province (BPIP)
• Thulean Plateau

See also

• Igneous rock
• Geologic province
• Mantle plume
• Hotspot
• Oceanic plateau
• Continental flood basalt
• Large igneous province
• Dike swarm

References

1. ^ North Atlantic Volcanic Margins: Dimensions and Production Rates; Eldholm and Grue, Journal of Geophysical Research, 1994; Abstract[1]; ”Quantitative calculations of NAVP dimensions, considered minimum estimates, reveal an areal extent of 1.3×10⁶ 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. ^ The North Atlantic Igneous Province: Stratigraphy, Tectonic, Volcanic and Magmatic Processes; Editors: Jolley and Bell; The Geological Society of London, 2002; Contents[2]
3. ^ Sur l'âge des trapps basaltiques - On the ages of flood basalt events; Courtillot and Renne; Comptes Rendus Geoscience, 2003; page down to p7-Brito-Arctic Province section[3] - section also discusses age, pulses of activity, and volume
4. ^ The Evolution of The North Atlantic Igneous Province and the Opening of the NE Atlantic Rift; Jolley and Bell; The Geological Society of London, 2002; Abstract[4]; “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. ^ The British Tertiary Volcanics: Origin, History and New Paleogeographic Constraints for the North Atlantic; Rousse, Ganerød, Smethurst, Torsvik, Prestvik; Geophysical Research Abstracts, 2007; Abstract[5]; "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. ^ North Atlantic Plate Motions and Plumes; Torsvik, Steinberger, and Gaina; Geophysical Research Abstracts, 2007; Abstract[6]; "Fixed hotspot frames show uniform NE movement of the coupled North American, Greenland, and Eurasian plates from ~95 to 80 Ma.”
7. ^ Structure and evolution of the continental margin off Norway and the Barents Sea; Faleide, Tsikalas, Breivik, Mjelde, Ritzmann, Engen, Wilson, and Eldholm; Episodes, 2008; Article[7]; "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. ^ 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; Melchior, Larsen, Rex, Watt, and Guise; Geology of Greenland Survey Bulletin, 1999; page down to p19[8] "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. ^ Development of the Continental Margins of the Labrador Sea: A Review; Chalmers and Pulvertaft; Geological Society, London, 2001; Abstract[9]; "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. ^ Tracking the Iceland Plume across the Arctic Ocean; Saunders, Drachev and Reichow; Geophysical Research Abstracts, 2005; Abstract[10]; "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. ^ ⁴⁰Ar/³⁹Ar Geochronology of Tertiary Mafic Intrusions along the East Greenland Rifted Margin: Relation to Flood Basalts and the Iceland Hotspot Track; Tegner, Duncan, Bernstein, Brooks, Bird, and Storey; Earth and Planetary Science Letters, 1998; Abstract[11]; "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. ^ Nature of Mantle Heterogeneity in the North Atlantic: Evidence from Deep Sea Drilling; Tarney, Wood, Saunders, Cann and Varet; Philosophical Transactions of the Royal Society of London, 1980; Abstract[12]; "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. ^ Pyroclastic Deposits within the East Greenland Tertiary Flood Basalts; Heister, O’Day, Brooks, Neuhoff, and Bird; Journal of the Geological Society, 2001; Abstract[13]; "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. ^ The Blosseville Coast Basalts of East Greenland: Their Occurrence, Composition and Temporal Variations; Brooks, Nielsen, and Petersen; Contributions to Mineralogy and Petrology, 1976; Abstract[14]; "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…”

External links

• Map of NAIP [15] - from Mantle Sources and Melting Dynamics in the British Paleogene British Province; Kent and Fitton, Journal of Petrology, 2000; article[16]
• Paleogeographic Map of NAIP[17] - from The Sub Lithospheric Source Of North Atlantic Basalts; Ellam and Stuart; Journal of Petrology, 2000; article[18]
• Mantle Plumes - Iceland Hotspot page[19]
• Large Igneous Province Commission - home page[20]