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The 1501 Ma Kuonamka Large Igneous Province of northern Siberia : U-Pb geochronology, geochemistry, and links with coeval magmatism on other crustal blocks

Ernst, R. E.; Okrugin, A. V.; Veselovskiy, R. V.; Kamo, S. L.; Hamilton, Michael A.; Pavlov, V.; Soderlund, U. LU ; Chamberlain, Kevin R. and Rogers, Chad N (2016) In Russian Geology and Geophysics 57(5). p.653-671
Abstract

A new large igneous province (LIP), the 1501 ± 3 Ma Kuonamka LIP, extends across 700 km of northern Siberia and is linked with coeval dikes and sills in the formerly attached Sao Francisco craton (SFC)-Congo craton to yield a short-duration event 2000 km across. The age of the Kuonamka LIP can be summarized as 1501 ± 3 Ma (95% confidence), based on 7 U-Pb ID-TIMS ages (6 new herein) from dolerite dikes and sills across the Anabar shield and within western Riphean cover rocks for a distance of 270 km. An additional sill yielded a SIMS (CAMECA) age of 1483 ± 17 Ma and sill in the Olenek uplift several hundred kilometers farther east, a previous SIMS (SHRIMP) age of ca. 1473 Ma was obtained on a sill; both SIMS ages are within the age... (More)

A new large igneous province (LIP), the 1501 ± 3 Ma Kuonamka LIP, extends across 700 km of northern Siberia and is linked with coeval dikes and sills in the formerly attached Sao Francisco craton (SFC)-Congo craton to yield a short-duration event 2000 km across. The age of the Kuonamka LIP can be summarized as 1501 ± 3 Ma (95% confidence), based on 7 U-Pb ID-TIMS ages (6 new herein) from dolerite dikes and sills across the Anabar shield and within western Riphean cover rocks for a distance of 270 km. An additional sill yielded a SIMS (CAMECA) age of 1483 ± 17 Ma and sill in the Olenek uplift several hundred kilometers farther east, a previous SIMS (SHRIMP) age of ca. 1473 Ma was obtained on a sill; both SIMS ages are within the age uncertainty of the ID-TIMS ages. Geochemical data indicate a tholeiitic basalt composition with low MgO (4-7 wt%) within-plate character based on trace element classification diagrams and source between E-MORB and OIB with only minor contamination from crust or metasomatized lithospheric mantle. Two subgroups are distinguished: Group 1 has gently sloping LREE ((La/Sm)PM = 1.9) and HREE ((Gd/Yb)PM = 1.8) patterns, slightly negative Sr and moderate TiO2 (2.2 wt%), and Group 2 has steeper LREE ((La/Sm)PM = 2.3) and HREE ((Gd/Yb)PM = 2.3), strong negative Sr anomaly, is higher in TiO2 (2.7 wt%), and is transitional from tholeiitic to weakly alkaline in composition. The slight differences in REE slopes are consistent with Group 2 on average melting at deeper levels. Proposed reconstructions of the Kuonamka LIP with 1500 Ma magmatism of the SFC-Congo craton are supported by a geochemical comparison. Specifically, the chemistry of the Chapada Diamantina and Curaga dikes of the SFC can be linked to that of Groups 1 and 2, respectively, of the Kuonamka LIP and are consistent with a common mantle source between EMORB and OIB and subsequent differentiation history. However, the coeval Humpata sills and dikes of the Angola block of the Congo craton represent a different magma batch.

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Contribution to journal
publication status
published
subject
keywords
Dikes, Igneous province, Magmatism, Northern Siberia, Sills
in
Russian Geology and Geophysics
volume
57
issue
5
pages
19 pages
publisher
Elsevier
external identifiers
  • scopus:84969804367
  • wos:000377370700003
ISSN
1068-7971
DOI
10.1016/j.rgg.2016.01.015
language
English
LU publication?
yes
id
fb454823-dfa7-4b7b-b718-620e5e70870c
date added to LUP
2017-02-02 14:15:29
date last changed
2017-11-19 04:37:15
@article{fb454823-dfa7-4b7b-b718-620e5e70870c,
  abstract     = {<p>A new large igneous province (LIP), the 1501 ± 3 Ma Kuonamka LIP, extends across 700 km of northern Siberia and is linked with coeval dikes and sills in the formerly attached Sao Francisco craton (SFC)-Congo craton to yield a short-duration event 2000 km across. The age of the Kuonamka LIP can be summarized as 1501 ± 3 Ma (95% confidence), based on 7 U-Pb ID-TIMS ages (6 new herein) from dolerite dikes and sills across the Anabar shield and within western Riphean cover rocks for a distance of 270 km. An additional sill yielded a SIMS (CAMECA) age of 1483 ± 17 Ma and sill in the Olenek uplift several hundred kilometers farther east, a previous SIMS (SHRIMP) age of ca. 1473 Ma was obtained on a sill; both SIMS ages are within the age uncertainty of the ID-TIMS ages. Geochemical data indicate a tholeiitic basalt composition with low MgO (4-7 wt%) within-plate character based on trace element classification diagrams and source between E-MORB and OIB with only minor contamination from crust or metasomatized lithospheric mantle. Two subgroups are distinguished: Group 1 has gently sloping LREE ((La/Sm)<sub>PM</sub> = 1.9) and HREE ((Gd/Yb)<sub>PM</sub> = 1.8) patterns, slightly negative Sr and moderate TiO<sub>2</sub> (2.2 wt%), and Group 2 has steeper LREE ((La/Sm)<sub>PM</sub> = 2.3) and HREE ((Gd/Yb)<sub>PM</sub> = 2.3), strong negative Sr anomaly, is higher in TiO<sub>2</sub> (2.7 wt%), and is transitional from tholeiitic to weakly alkaline in composition. The slight differences in REE slopes are consistent with Group 2 on average melting at deeper levels. Proposed reconstructions of the Kuonamka LIP with 1500 Ma magmatism of the SFC-Congo craton are supported by a geochemical comparison. Specifically, the chemistry of the Chapada Diamantina and Curaga dikes of the SFC can be linked to that of Groups 1 and 2, respectively, of the Kuonamka LIP and are consistent with a common mantle source between EMORB and OIB and subsequent differentiation history. However, the coeval Humpata sills and dikes of the Angola block of the Congo craton represent a different magma batch.</p>},
  author       = {Ernst, R. E. and Okrugin, A. V. and Veselovskiy, R. V. and Kamo, S. L. and Hamilton, Michael A. and Pavlov, V. and Soderlund, U. and Chamberlain, Kevin R. and Rogers, Chad N},
  issn         = {1068-7971},
  keyword      = {Dikes,Igneous province,Magmatism,Northern Siberia,Sills},
  language     = {eng},
  month        = {05},
  number       = {5},
  pages        = {653--671},
  publisher    = {Elsevier},
  series       = {Russian Geology and Geophysics},
  title        = {The 1501 Ma Kuonamka Large Igneous Province of northern Siberia : U-Pb geochronology, geochemistry, and links with coeval magmatism on other crustal blocks},
  url          = {http://dx.doi.org/10.1016/j.rgg.2016.01.015},
  volume       = {57},
  year         = {2016},
}