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New U–Pb ages for mafic dykes in the Northwestern region of the Ukrainian shield : coeval tholeiitic and jotunitic magmatism

Shumlyanskyy, Leonid; Ernst, Richard E.; Söderlund, Ulf LU ; Billström, Kjell; Mitrokhin, Oleksandr and Tsymbal, Stepan (2016) In GFF 138(1). p.79-85
Abstract

The palaeoproterozoic Northwestern region of the Ukrainian shield hosts two compositional types of mafic dykes and associated magmatism that intruded at c. 1800–1760 Ma: (1) high-Ni dolerite dykes and layered intrusions of tholeiitic affinity and (2) high-Ti dolerite dykes of jotunitic affinity associated with anorthosite–mangerite–charnockite–granite (AMCG) suites. The jotunitic dykes represent initial melts for basic rocks of the Korosten AMCG plutonic complex, whereas tholeiitic dykes may reflect emplacement of a mantle plume and formation of a large igneous province (LIP). New U–Pb baddeleyite ages indicate that both compositional types can be coeval: the jotunitic Rudnya Bazarska dyke was emplaced at 1793 ± 3 Ma, and the... (More)

The palaeoproterozoic Northwestern region of the Ukrainian shield hosts two compositional types of mafic dykes and associated magmatism that intruded at c. 1800–1760 Ma: (1) high-Ni dolerite dykes and layered intrusions of tholeiitic affinity and (2) high-Ti dolerite dykes of jotunitic affinity associated with anorthosite–mangerite–charnockite–granite (AMCG) suites. The jotunitic dykes represent initial melts for basic rocks of the Korosten AMCG plutonic complex, whereas tholeiitic dykes may reflect emplacement of a mantle plume and formation of a large igneous province (LIP). New U–Pb baddeleyite ages indicate that both compositional types can be coeval: the jotunitic Rudnya Bazarska dyke was emplaced at 1793 ± 3 Ma, and the Zamyslovychi tholeiitic dolerite dyke at 1789 ± 9 Ma. In our model, the mantle plume-derived tholeiitic melts (underplate) supplied heat required for melting of the mafic lower crust and the production of jotunitic melts. As formation of the jotunite melts requires pressures in the range 10–13 kbar, either a thickened crust is needed or the lower crust must be subducted, or downthrusted, into the mantle. Alternatively, emplacement and ponding of large volume of tholeiitic melts might cause delamination of the lower crust, its sinking into the mantle, and further fusion to produce jotunitic melts.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
baddeleyite, mafic dykes, palaeoproterozoic, Ukrainian shield, U–Pb dating, zircon
in
GFF
volume
138
issue
1
pages
7 pages
publisher
Geological Society of Sweden
external identifiers
  • Scopus:84959088456
ISSN
1103-5897
DOI
10.1080/11035897.2015.1116602
language
English
LU publication?
yes
id
db5d0896-ff77-45fb-ab7e-1291c0e89d36
date added to LUP
2016-09-20 12:54:16
date last changed
2016-11-09 08:24:21
@misc{db5d0896-ff77-45fb-ab7e-1291c0e89d36,
  abstract     = {<p>The palaeoproterozoic Northwestern region of the Ukrainian shield hosts two compositional types of mafic dykes and associated magmatism that intruded at c. 1800–1760 Ma: (1) high-Ni dolerite dykes and layered intrusions of tholeiitic affinity and (2) high-Ti dolerite dykes of jotunitic affinity associated with anorthosite–mangerite–charnockite–granite (AMCG) suites. The jotunitic dykes represent initial melts for basic rocks of the Korosten AMCG plutonic complex, whereas tholeiitic dykes may reflect emplacement of a mantle plume and formation of a large igneous province (LIP). New U–Pb baddeleyite ages indicate that both compositional types can be coeval: the jotunitic Rudnya Bazarska dyke was emplaced at 1793 ± 3 Ma, and the Zamyslovychi tholeiitic dolerite dyke at 1789 ± 9 Ma. In our model, the mantle plume-derived tholeiitic melts (underplate) supplied heat required for melting of the mafic lower crust and the production of jotunitic melts. As formation of the jotunite melts requires pressures in the range 10–13 kbar, either a thickened crust is needed or the lower crust must be subducted, or downthrusted, into the mantle. Alternatively, emplacement and ponding of large volume of tholeiitic melts might cause delamination of the lower crust, its sinking into the mantle, and further fusion to produce jotunitic melts.</p>},
  author       = {Shumlyanskyy, Leonid and Ernst, Richard E. and Söderlund, Ulf and Billström, Kjell and Mitrokhin, Oleksandr and Tsymbal, Stepan},
  issn         = {1103-5897},
  keyword      = {baddeleyite,mafic dykes,palaeoproterozoic,Ukrainian shield,U–Pb dating,zircon},
  language     = {eng},
  month        = {01},
  number       = {1},
  pages        = {79--85},
  publisher    = {ARRAY(0x127bf968)},
  series       = {GFF},
  title        = {New U–Pb ages for mafic dykes in the Northwestern region of the Ukrainian shield : coeval tholeiitic and jotunitic magmatism},
  url          = {http://dx.doi.org/10.1080/11035897.2015.1116602},
  volume       = {138},
  year         = {2016},
}