Metallogeny of gold in the Fennoscandian Shield

Gaál, Gabor; Sundblad, Krister

doi:10.1007/bf00205257

Cited by 15 publications

(2 citation statements)

References 47 publications

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“…Gold mineralization likely formed in the postcollisional stage in the transition to the platform stage of development [25,26]. A similar time sequence in terms of magmatism in porphyry-type gold deposits has been described in Baltic shield granitoids in Finland (aged 1.9-1.8 Ga) [27,28].…”

Section: Petrochemistry Of Ore-hosting Rockssupporting

confidence: 53%

Typomorphic Features of Placer Gold from the Billyakh Tectonic Melange Zone of the Anabar Shield and Its Potential Ore Sources (Northeastern Siberian Platform)

2020

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Precambrian shields and outcropped Precambrian rock complexes in the Arctic may serve as the most important sources of various types of mineral raw materials, including gold. The gold potential of the Anabar shield in the territory of Siberia has, thus far, been poorly studied. A number of primary and placer gold occurrences have been discovered there, but criteria for the prediction of and search for gold mineralization remain unclear. The main purpose of this paper was to study the typomorphic features of placer gold in the central part of the Billyakh tectonic mélange zone in the Anabar shield and to compare them to mineralization from primary sources. To achieve this, we utilized common methods for mineralogical, petrographic, and mineragraphic analyses. Additionally, geochemical data were used. As a result of this investigation, important prospecting guides were identified, and essential criteria for the prediction of and search for gold deposits were elucidated. The characteristics of the studied placer gold were specific for gold derived from a proximal provenance. These characteristics included the poor roundness of the native gold grains, a cloddy–angular and dendritic form, an uneven surface, and a high content of coarse-fraction native gold (0.5–2 mm), which was as high as 24% of the volume of analyzed native gold. In addition, we conducted a study on the mineralogical features of the gold-sulfide mineralization that was disseminated throughout a small exposure area of paleo-Proterozoic para- and orthogneisses in the Anabar shield basement. A comparison of mineral inclusions in the coarse-fraction native gold and mineral assemblages in the ore deposits showed that one of the possible primary sources for placer gold might be small bodies of metasomatically altered orthogneisses associated with large granitoid plutons.

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Section: Petrochemistry Of Ore-hosting Rockssupporting

confidence: 53%

Typomorphic Features of Placer Gold from the Billyakh Tectonic Melange Zone of the Anabar Shield and Its Potential Ore Sources (Northeastern Siberian Platform)

2020

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“…The most well-known examples are the Fredriksberg Cu-Zn-Pb sulphide deposit hosted by metavolcanic rocks (Sundblad et al 1997), the Sunnerskog Cu-W-Mo skarn deposit hosted by metagreywacke (Persson 1989), the Ä delfors tectonically related, gold-bearing quartz veins hosted by mafic metavolcanic rocks (Gaál & Sundblad 1990) and minor Ni mineralisations in a layered gabbro in Virserum to the southeast of Kleva (Tegengren 1924). The OJB consists of calcalkaline igneous and supracrustal rocks and is proposed to have formed during subduction of oceanic lithosphere under a continent or mature arc along the active margin of Fennoscandia (Å häll et al 2002;Mansfeld et al 2005).…”

Section: Geological Settingmentioning

confidence: 98%

Geochronology and geochemical evidence for a magmatic arc setting for the Ni-Cu mineralised 1.79 Ga Kleva gabbro–diorite intrusive complex, southeast Sweden

Bjärnborg

Scherstén

Maier

2015

GFF

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Magmatic Ni-Cu sulphide deposits are commonly associated with mafic rocks within the marginal areas of Archean or Proterozoic cratons. The Kleva Ni-Cu sulphide deposit in southeast Sweden is hosted by gabbro-diorite rocks and is sandwiched between two Palaeoproterozoic magmatic arcs: the Transscandinavian Igneous Belt (TIB) and the Oskarshamn-Jönköping Belt (OJB). Major and trace element data corroborate an arc origin for the Kleva intrusive complex. The variety of rocks and geochemical signatures suggest that it formed from several magmatic pulses. Despite the occurrence of supracrustal xenoliths, there is a lack of trace element evidence for significant assimilation. Mafic intrusions are abundant in southeast Sweden and are generally inferred to be synchronous with the TIB. Of these, Kleva is the only known Ni-Cu deposit, and it is unclear if it is associated with the OJB or TIB. Here, we present zircon and baddeleyite U-Pb dates of 1788^4 Ma, 1788^5 Ma and 1792^3 Ma. We interpret a 1790 Ma date to be the best estimate of the crystallisation age of the Kleva intrusive complex, indicating that the emplacement of mafic magma is coeval with the voluminous arc-related TIB magmatism in the area.

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Source of metals and age constraints for epigenetic gold deposits in the Skellefte and Pohjanmaa districts, central part of the Fennoscandian Shield

et al. 1993

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Abstract. The lead isotopic compositions of galena in Early Proterozoic gold deposits have been determined for three districts in northern Sweden and central Finland. The deposits are hosted by a variety of ~ 1870-1890 Ma Svecofennian host rocks including the volcanosedimentary succession within the Skellefte District island arc in Sweden as well as I-type tonalites at J6rn (Sweden) and Pohjanmaa (Finland). The deposits are epigenetic in relation to these Svecofennian rocks and are part of a goldbearing metallogenetic belt, which can be followed for 600 km parallel to the southwestern margin of the Archaean Domain. In spite of these epigenetic relationships, the lead isotopic data indicate that the deposits are not dramatically younger than the ~1870-1890 Ma Svecofennian host rocks (probably not exceeding 10-20 million years). Two principal lead sources were activated when the gold deposits were formed.-The most significant source is represented by the I-type tonalites, which constitute a relatively primitive (/~ = 9.3) and widely distributed source in the entire metaUogenic belt. In addition, the volcanic components in the westernmost part of the Skellefte District constitute an extremely primitive (~ < 9.0) source, which only locally was an important contributor to the epigenetic deposits in this metallogenetic belt. The significantly different lead isotopic composition estimated for these sources indicates that the volcanic rocks in the western part of the SkeUefte District were not comagmatic with the I-type tonalites recognized at J6rn and central Finland.partly related to volcanogenic massive sulphide deposits of the Skellefte type, partly related to synkinematic intrusions of the J6rn type and partly related to major shear zone structures. This complex metallogenetic province can be followed over a length of about 600 km and includes the Skellefte mining district in northern Sweden, and the 'main sulphide belt' of central Finland (Fig. 1). Volcanogenic massive sulphide deposits (VMS) and Niores were until recently the only ore types which were mined in this province, but during the last decade, increasing interest has also been focused on gold lode deposits and two gold mines have come into production since 1988.The origin of the massive sulphide deposits and the Ni-ores has been discussed in a number of papers (see e.g.

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Metallogeny of gold in the Fennoscandian Shield

Cited by 15 publications

References 47 publications

Typomorphic Features of Placer Gold from the Billyakh Tectonic Melange Zone of the Anabar Shield and Its Potential Ore Sources (Northeastern Siberian Platform)

Typomorphic Features of Placer Gold from the Billyakh Tectonic Melange Zone of the Anabar Shield and Its Potential Ore Sources (Northeastern Siberian Platform)

Geochronology and geochemical evidence for a magmatic arc setting for the Ni-Cu mineralised 1.79 Ga Kleva gabbro–diorite intrusive complex, southeast Sweden

Source of metals and age constraints for epigenetic gold deposits in the Skellefte and Pohjanmaa districts, central part of the Fennoscandian Shield

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