scholarly journals Paleoproterozoic Pt-Pd Fedorovo-Pansky and Cu-Ni-Cr Monchegorsk Ore Complexes: Age, Metamorphism, and Crustal Contamination According to Sm-Nd Data

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1410
Author(s):  
Pavel A. Serov
Keyword(s):  
Baltic Shield ◽  
Age Determination ◽  
Crustal Contamination ◽  
Interaction Model ◽  
Fennoscandian Shield ◽  
Layered Intrusions ◽  
Ore Formation ◽  
Nd Isotope ◽  
Parental Melts

This paper continues the Sm-Nd isotope geochronological research carried out at the two largest Paleoproterozoic ore complexes of the northeastern Baltic Shield, i.e., the Cu-Ni-Cr Monchegorsk and the Pt-Pd Fedorovo-Pansky intrusions. These economically significant deposits are examples of layered complexes in the northeastern part of the Fennoscandian Shield. Understanding the stages of their formation and transformation helps in the reconstruction of the long-term evolution of ore-forming systems. This knowledge is necessary for subsequent critical metallogenic and geodynamic conclusions. We applied the Sm-Nd method of comprehensive age determination to define the main age ranges of intrusion. Syngenetic ore genesis occurred 2.53–2.85 Ga; hydrothermal metasomatic ore formation took place 2.70 Ga; and the injection of additional magma batches occurred 2.44–2.50 Ga. The rock transformation and redeposited ore formation at 2.0–1.9 Ga corresponded to the beginning of the Svecofennian events, widely presented on the Fennoscandian Shield. According to geochronological and Nd-Sr isotope data, rocks of the Monchegorsk and the Fedorovo-Pansky complexes seemed to have an anomalous mantle source in common with Paleoproterozoic layered intrusions of the Fennoscandian Shield (enriched with lithophile elements, εNd values vary from −3.0 to +2.5 and ISr 0.702–0.705). The data obtained comply with the known isotope-geochemical and geochronological characteristics of ore-bearing layered intrusions in the northeastern Baltic Shield. An interaction model of parental melts of the Fennoscandian layered intrusions and crustal matter shows a small level of contamination within the usual range of 5–10%. However, the margins of the Monchetundra massif indicate a much higher level of crustal contamination caused by active interaction of parental magmas and host rock.

scholarly journals Biosignatures of ancient microbial life are present across the igneous crust of the Fennoscandian shield

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Henrik Drake ◽  
Nick M. W. Roberts ◽  
Manuel Reinhardt ◽  
Martin Whitehouse ◽  
Magnus Ivarsson ◽  
...  
Keyword(s):  
Fennoscandian Shield ◽  
Stable Carbon ◽  
Deep Biosphere ◽  
Isotopic Signatures ◽  
Microbial Life ◽  
Carbon Isotopic ◽  
Terrestrial Life ◽  
Vein Mineral ◽  
Methyl Branched Fatty Acids

AbstractEarth’s crust contains a substantial proportion of global biomass, hosting microbial life up to several kilometers depth. Yet, knowledge of the evolution and extent of life in this environment remains elusive and patchy. Here we present isotopic, molecular and morphological signatures for deep ancient life in vein mineral specimens from mines distributed across the Precambrian Fennoscandian shield. Stable carbon isotopic signatures of calcite indicate microbial methanogenesis. In addition, sulfur isotope variability in pyrite, supported by stable carbon isotopic signatures of methyl-branched fatty acids, suggest subsequent bacterial sulfate reduction. Carbonate geochronology constrains the timing of these processes to the Cenozoic. We suggest that signatures of an ancient deep biosphere and long-term microbial activity are present throughout this shield. We suggest that microbes may have been active in the continental igneous crust over geological timescales, and that subsurface investigations may be valuable in the search for extra-terrestrial life.

Age of metasomatism and ore formation in the Srednyaya Padma vanadium-precious metals-uranium deposit (Karelia, Baltic Shield)

2014 ◽  
Vol 454 (1) ◽  
pp. 68-71
Author(s):  
A. P. Borozdin ◽  
Yu. S. Polekhovskii ◽  
S. A. Bushmin ◽  
V. A. Glebovitskii ◽  
B. V. Belyatskii ◽  
...  
Keyword(s):  
Baltic Shield ◽  
Uranium Deposit ◽  
Precious Metals ◽  
Ore Formation

A Ce/Nd isotope study of crustal contamination processes affecting Palaeocene magmas in Skye, Northwest Scotland

1987 ◽  
Vol 96 (4) ◽  
pp. 455-464 ◽  
Author(s):  
A. P. Dickin ◽  
N. W. Jones ◽  
M. F. Thirlwall ◽  
R. N. Thompson
Keyword(s):  
Crustal Contamination ◽  
Nd Isotope ◽  
Isotope Study

scholarly journals Was Crustal Contamination Involved in the Formation of the Serpentine-Free Udachnaya-East Kimberlite? New Insights into Parental Melts, Liquidus Assemblage and Effects of Alteration

2018 ◽  
Vol 59 (8) ◽  
pp. 1467-1492 ◽  
Author(s):  
Adam Abersteiner ◽  
Vadim S Kamenetsky ◽  
Alexander V Golovin ◽  
Maya Kamenetsky ◽  
Karsten Goemann
Keyword(s):  
Crustal Contamination ◽  
Parental Melts

Oxygen-Hafnium-Neodymium Isotope Constraints on the Origin of the Talnakh Ultramafic-Mafic Intrusion (Norilsk Province, Russia)

2020 ◽  
Vol 115 (6) ◽  
pp. 1195-1212 ◽  
Author(s):  
Kreshimir N. Malitch ◽  
Elena A. Belousova ◽  
William L. Griffin ◽  
Laure Martin ◽  
Inna Yu. Badanina ◽  
...  
Keyword(s):  
Crustal Contamination ◽  
Ultramafic Rocks ◽  
Magma Chambers ◽  
Nd Isotope ◽  
Crustal Component ◽  
Depleted Mantle ◽  
Magma Sources ◽  
A Minor ◽  
T Values

Abstract The ultramafic-mafic Talnakh intrusion in the Norilsk province (Russia) hosts one of the world’s major platinum group element (PGE)-Cu-Ni sulfide deposits. This study employed a multitechnique approach, including in situ Hf-O isotope analyses of zircon combined with whole-rock Nd isotope data, in order to gain new insights into genesis of the Talnakh economic intrusion. Zircons from gabbrodiorite, gabbroic rocks of the layered series, and ultramafic rocks have similar mantle-like mean δ18O values (5.39 ± 0.49‰, n = 27; 5.64 ± 0.48‰, n = 34; and 5.28 ± 0.34‰, n = 7, respectively), consistent with a mantle-derived origin for the primary magma(s) parental to the Talnakh intrusion. In contrast, a sulfide-bearing taxitic-textured troctolite from the basal part of intrusion has high δ18O (mean of 6.50‰, n = 3), indicating the possible involvement of a crustal component during the formation of sulfide-bearing taxitic-textured rocks. The Hf isotope compositions of zircon from different rocks of the Talnakh intrusion show significant variations, with ɛHf(t) values ranging from –3.2 to 9.8 for gabbrodiorite, from –4.3 to 11.6 for unmineralized layered-sequence gabbroic rocks, from 2.3 to 12 for mineralized ultramafic rocks, and from –3.5 to 8.8 for mineralized taxitic-textured rocks at the base of the intrusion. The significant range in the initial 176Hf/177Hf values is ascribed to interaction of distinct magma sources during formation of the Talnakh intrusion. These include (1) a juvenile source equivalent to the depleted mantle, (2) a subcontinental lithospheric source, and (3) a minor crustal component. Initial whole-rock Nd isotope compositions of the mineralized taxitic-textured rocks from the base of the intrusion (mean ɛNd(t) = –1.5 ± 1.8) differ from the other rocks, which have relatively restricted ranges in initial ɛNd (mean ɛNd = 0.9 ± 0.2). The major set of ɛNd values around 1.0 at Talnakh is attributed to limited crustal contamination, presumably in deep magma chambers, whereas the smaller set of negative ɛNd values in taxitic-textured rocks is consistent with greater involvement of a crustal component and reflects an interaction with the wall rocks during emplacement.

scholarly journals 8: Precambrian geodynamics and ore formation: The Fennoscandian Shield

2005 ◽  
Vol 27 (1-4) ◽  
pp. 273-322 ◽  
Author(s):  
Pär Weihed ◽  
Nicholas Arndt ◽  
Kjell Billström ◽  
Jean-Clair Duchesne ◽  
Pasi Eilu ◽  
...  
Keyword(s):  
Fennoscandian Shield ◽  
Ore Formation

scholarly journals New U-Pb and Sm-Nd Data and REE Distribution in Sulphides of Paleoproterozoic PGE Layered Intrusions in the Arctic Part of the Fennoscandian Shield

2019 ◽  
Vol 09 (11) ◽  
pp. 768-782
Author(s):  
Tamara Bayanova ◽  
Irina Elizarova ◽  
Pavel Serov ◽  
Nadezhda Ekimova ◽  
Evgeny Kunakkuzin ◽  
...  
Keyword(s):  
Fennoscandian Shield ◽  
The Arctic ◽  
Layered Intrusions ◽  
Ree Distribution

Isotope systematics (Pb-Nd-Sr) and LA-ICP-MS (REE, Os, PGE) data on time, duration and origin of Paleoproterozoic complex deposits in the N-E part of the Arctic region, Fennoscandian Shield

2021 ◽  
Author(s):  
Tamara Bayanova ◽  
Pavel Serov ◽  
Svetlana Drogobuzhskaya
Keyword(s):  
Arctic Region ◽  
Fennoscandian Shield ◽  
The Arctic ◽  
Layered Intrusions ◽  
Time Duration ◽  
Time Activity ◽  
Sulphide Minerals ◽  
Icp Ms ◽  
Mantle Reservoir ◽  
Isotope Systematics

<p>The isotope U-Pb system on zircon and baddeleyite reflects the precise age of the origin (2.5, 2.45 and 2.4 Ga) and duration (more than 100 Ma) for Cu-Ni and PGE complex deposits widespread in the N-E part of the Fennoscandian Shield. The Monchegorsk, Fedorovo-Pansky and Mt. Generalskaya layered intrusions and ore regions of the orthomagmatic Cu-Ni and PGE deposits with Pt-Pd reefs originated on the continental crust (3.7 Ga). Main phases of gabbronorites were formed mainly at 2.5 Ga and secondary anorthosites at 2.45 Ga, according to U-Pb data on zircon-baddeleyite geochronometries. The Imandra lopolith with Cr deposits was active from 2.45 Ga to 2.4 Ga due to dyke deformation complexes. Isotope Sm-Nd studies and investigations of rock-forming and sulphide minerals from the deposits indicated coeval ages and 3 magmatic time activity with positive epsilon Nd. Deformation or metamorphic events were dated using the Rb-Sr system on minerals and whole rocks from the deposits at 1.9-1.8 Ga.</p><p>The Pados Cr (2.08 Ga), Pechenga Cu-Ni (1.98 Ga) and Kolvitsa Ti-Mg (1.89 Ga) orthomagmatic deposits were dated, using the Pb-Nd-Sr isotope systematics. The mentioned deposits originated probably on the oceanic crust (2.7 Ga). According to new in situ LA-ICP-MS data on Os, PGE and REE concentration in zircon, baddeleyite and sulphide minerals from the complex deposits are characterized by subchondritic sources (Malitch et al., 2019). Paleoproterozoic layered intrusions (2.5-1.8 Ga) and deposits were formed from the plume enrichment mantle reservoir (EM-1), according to Nd-Sr data on whole rocks. Baddeleyite as a mantle mostly mineral (Zircon, 2003) reflects the continental break-up and is connected with the oldest supercontinental reconstruction (Ernst, 2016).</p><p>All studies have been supported by RFRB 18-05-70082, Scientific Research Contracts Nos 0226-2019-0032 and 0226-2019-0053.</p>

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