The Kandalaksha-Kolvitsa gabbro-anorthosite complex: Nd-Sr isotope-geochronological evidence of its affinity to the East-Scandinavian Large Igneous Province

The article provides new Sm-Nd and Nd-Sr isotope-geochronological data on rocks of the Paleoproterozoic Kandalaksha-Kolvitsa gabbro-anorthosite complex.The Sm-Nd and Rb-Sr studies have provided data on isotope compositions of neodymium and strontium in rocks of both massifs. The isotope compositions of neodymium (eNd) range from -0.02 in norites of the Kandalaksha massif to -5.53 in lens bodies of gneiss granites of the Kolvitsa massifWeakly radiogenic values of eNd = -1.0 &#8211; -1.2 dominate, which complies with characteristic values of Paleoproterozoic layered intrusions in Fennoscandia. Isotope compositions of strontium ranging from 0.7013 to 0.7025 also reflect typical values of a Paleoproterozoic igneous province [.New data suggest that the Kandalaksha-Kolvitsa gabbro-anorthosite complex is confined to the East-Scandinavian Large Igneous Province with a protracted evolution at the turn of 2.53-2.39 Ga. According to geochronological and isotope Nd-Sr data, rocks of the Kandalaksha-Kolvitsa complex seem to have the same anomalous mantle source with Paleoproterozoic layered intrusions in the Baltic Shield (Fig. 3). The latter include Cu-Ni-Co-Cr+PGE deposits in the Monchegorsk ore area and Pechenga, Cr ores in the Pados massif, Fe-Ti-V Kolvitsa deposit, PGE and Cu-Ni Fedorovo-Pana layered complex &#160;and Burakovsky intrusion, Cu-Ni-Co+PGE deposits in Finland, i.e. Kemi, Penikat, Akanvaara, Kontelainen, Tornio and many other. These deposits formed at two episodes, 2.53-2.39 Ga and 2.0-1.8 Ga, that refer to the beginning of rifting and the late rifting stage of the Fennoscandian Shield evolution, respectively.Rocks of these intrusions referred to the pyroxenite-gabbronorite-anorthosite formation have similar isotope-geochemical features:1) according to U-Pb and Sm-Nd geochronological data, the formation time span is 2530 to 2380 Ma;2) the mantle reservoir feeding magmas that formed the massifs is rich in lithophile elements;&#160; ISr values vary from 0.702 to 0.706, &#949;Nd(T) varies from +2 to -6;3) the model Sm-Nd ages of TDM protoliths are 2.8-3.3 Ga.The scientific research has been carried out in the framework of the State Research Contract of GI KS&#1057; RAS No. 0226-2019-0053, RFBR grant No. 18-05-70082 &#171;Arctic&#8217;s Resources&#187; and Presidium RAS Program No. 8.

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Os, Nd and Sr isotope and trace element geochemistry of the Muli picrites: Insights into the mantle source of the Emeishan Large Igneous Province

Lithos ◽

10.1016/j.lithos.2010.06.002 ◽

2010 ◽

Vol 119 (1-2) ◽

pp. 108-122 ◽

Cited By ~ 57

Author(s):

Jie Li ◽

Ji-Feng Xu ◽

Katsuhiko Suzuki ◽

Bin He ◽

Yi-Gang Xu ◽

...

Keyword(s):

Trace Element ◽

Mantle Source ◽

Large Igneous Province ◽

Trace Element Geochemistry ◽

Sr Isotope ◽

Element Geochemistry ◽

Emeishan Large Igneous Province ◽

Igneous Province

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Decision letter for "Mafic subvolcanic intrusions from the southern Paraná‐Etendeka Large Igneous Province, Brazil: Insights from geochemistry and Sr–Nd–Pb isotopes"

10.1002/gj.3993/v3/decision1 ◽

2020 ◽

Keyword(s):

Large Igneous Province ◽

Igneous Province

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Lithostratigraphy of the Palaeoproterozoic Hekpoort Formation (Pretoria Group, Transvaal Supergroup), South Africa

South African Journal of Geology ◽

10.25131/sajg.123.0043 ◽

2020 ◽

Vol 123 (4) ◽

pp. 655-668

Author(s):

N. Lenhardt ◽

W. Altermann ◽

F. Humbert ◽

M. de Kock

Keyword(s):

South Africa ◽

Bushveld Complex ◽

Sedimentary Rocks ◽

Type Locality ◽

Large Igneous Province ◽

Braided River ◽

River Systems ◽

The West ◽

Igneous Province ◽

Transvaal Supergroup

Abstract The Palaeoproterozoic Hekpoort Formation of the Pretoria Group is a lava-dominated unit that has a basin-wide extent throughout the Transvaal sub-basin of South Africa. Additional correlative units may be present in the Kanye sub-basin of Botswana. The key characteristic of the formation is its general geochemical uniformity. Volcaniclastic and other sedimentary rocks are relatively rare throughout the succession but may be dominant in some locations. Hekpoort Formation outcrops are sporadic throughout the basin and mostly occur in the form of gentle hills and valleys, mainly encircling Archaean domes and the Palaeoproterozoic Bushveld Complex (BC). The unit is exposed in the western Pretoria Group basin, sitting unconformably either on the Timeball Hill Formation or Boshoek Formation, which is lenticular there, and on top of the Boshoek Formation in the east of the basin. The unit is unconformably overlain by the Dwaalheuwel Formation. The type-locality for the Hekpoort Formation is the Hekpoort farm (504 IQ Hekpoort), ca. 60 km to the west-southwest of Pretoria. However, no stratotype has ever been proposed. A lectostratotype, i.e., the Mooikloof area in Pretoria East, that can be enhanced by two reference stratotypes are proposed herein. The Hekpoort Formation was deposited in a cratonic subaerial setting, forming a large igneous province (LIP) in which short-termed localised ponds and small braided river systems existed. It therefore forms one of the major Palaeoproterozoic magmatic events on the Kaapvaal Craton.

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Ultramafic-alkaline-carbonatite complexes as a result of two-stage melting of mantle plume: evidence from the mid-paleoproterozoic Tiksheozero intrusion, Northern Karelia, Russia

Доклады Академии наук ◽

10.31857/s0869-56524864460-465 ◽

2019 ◽

Vol 486 (4) ◽

pp. 460-465

Author(s):

E. V. Sharkov ◽

A. V. Chistyakov ◽

M. M. Bogina ◽

O. A. Bogatikov ◽

V. V. Shchiptsov ◽

...

Keyword(s):

Fractional Crystallization ◽

Mantle Plume ◽

Large Igneous Province ◽

Intrusive Complex ◽

Incongruent Melting ◽

Isotopic Data ◽

Two Stage ◽

Similar Composition ◽

Igneous Province ◽

Alkaline Magmas

Tiksheozero ultramafic-alkaline-carbonatite intrusive complex, like numerous carbonatite-bearing complexes of similar composition, is a part of large igneous province, related to the ascent of thermochemical mantle plume. Our geochemical and isotopic data evidence that ultramafites and alkaline rocks are joined by fractional crystallization, whereas carbonatitic magmas has independent origin. We suggest that origin of parental magmas of the Tiksheozero complex, as well as other ultramafic-alkaline-carbonatite complexes, was provided by two-stage melting of the mantle-plume head: 1) adiabatic melting of its inner part, which produced moderately-alkaline picrites, which fractional crystallization led to appearance of alkaline magmas, and 2) incongruent melting of the upper cooled margin of the plume head under the influence of CO2-rich fluids that arrived from underlying zone of adiabatic melting gave rise to carbonatite magmas.

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