| Titre | The Barika gold-bearing Kuroko-type volcanogenic massive sulfide (VMS) deposit, Sanandaj-Sirjan zone, Iran |
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| Auteur | Tajeddin, H A; Rastad, E; Yaghoubpour, A; Maghfouri, S; Peter, J M ; Goldfarb, R; Mohajjel, M |
| Source | Ore Geology Reviews vol. 113, 103081, 2019 p. 1-23, https://doi.org/10.1016/j.oregeorev.2019.103081 |
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| Année | 2019 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20190555 |
| Éditeur | Elsevier |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1016/j.oregeorev.2019.103081 |
| Media | papier; en ligne; numérique |
| Formats | pdf; html |
| Lat/Long OENS | 36.1808 36.1989 45.6553 45.6375 |
| Sujets | gisements minéraux; gîtes volcanogènes; gîtes sulfureux; or; argent; métaux de base; plomb; zinc; cuivre; antimoine; minéralisation; genèse des minerais; roches hôtes; antécédents tectoniques;
métamorphisme; déformation; cisaillement; recristallisation; formation de failles; faciès à schiste vert; système hydrothermal; volcanisme; filons; assemblages de minéraux; textures; inclusions fluides; salinité; analyses thermiques; etudes
isotopiques; isotopes d'oxygène; soufre; géologie économique; minéralogie; géochimie; tectonique; Sciences et technologie; Nature et environnement; Phanérozoïque; Mésozoïque; Crétacé |
| Illustrations | cartes géolscientiques généralisées; tableaux; photographies; coupes schématiques; graphiques; diagrammes ternaires; photomicrographies; cartes géochronologiques; histogrammes; graphique à barres;
représentations schématiques |
| Programme | Initiative géoscientifique ciblée (IGC-5) Systèmes minéralisés de sulfure massif volcanogénique - métaux de base - sources et processus |
| Diffusé | 2019 08 21 |
| Résumé | (disponible en anglais seulement)
The Barika deposit is the first documented auriferous Kuroko-type volcanogenic massive sulfide (VMS) deposit in Iran. It is hosted in meta-andesites of the
Sanandaj-Sirjan metamorphic Zone (SSZ). The mineralization and host rocks have been metamorphosed to lower greenschist facies. The deposit has Au and Ag grades in the stratiform lens averaging 3.5 and 175 g/t, respectively, and contains 2.3 tonnes of
Au and 143 tonnes of Ag. The base metal (Pb + Zn + Cu) content of the deposit is low (<1?wt%). The stratiform part of the Barika deposit is approximately 150 m long and up to 20 m thick, and consists of massive to semi-massive sulfides, some of which
are banded, which are overlain by barite and siliceous exhalites. The >200 m long and up to 500 m wide stringer zone immediately stratigraphically underlies the stratiform mineralization. Veins within the stringer zone are composed of quartz, pyrite,
galena, sphalerite, tetrahedrite-tennantite, and rare chalcopyrite. Stratiform mineralization is composed of pyrite, sphalerite, galena, stibnite, tetrahedrite-tennantite, several Ag-(As-Sb-Pb) sulfosalt minerals (guettardite, ferdowsiite, barikaite,
stephanite, pyrargyrite, trechmannite, miargyrite, As-rich andorite, As-rich geocronite, Sb-rich seligmanite and smithite), realgar, and electrum.
Based on mineral assemblages and textures, four mineralization stages are recognized. During stage
1, pyrite, sphalerite, galena, tetrahedrite-tennantite, and stibnite were deposited during synvolcanic hydrothermal activity. During stages 2 and 3, post-mineralization deformation and shearing contemporaneous with regional metamorphism modified most
of the primary textures in the stratiform mineralization. Stage 2 mineralization represents Stage 1 mineralization that was remobilized during regional metamorphism, and this mineralization is characterized by gold as submicroscopic inclusions or as
'invisible' gold locked in pyrite, as well as electrum in the barite mineralization. Regional metamorphism and deformation (D1) caused recrystallization of primary mineralization (mainly pyrite) and migration of submicroscopic gold via
solution-precipitation creep to the grain boundaries to form microscopic electrum. Stage 3 mineralization is attendant with D2 movement along the Barika shear zone that controlled the overall geometry of the deposit and resulted in the development of
ductile-brittle deformation textures and the formation of several Ag(As-Sb-Pb)-rich sulfosalt minerals and electrum. Most of the electrum grains occur together with sulfosalt minerals that fill open spaces formed during shearing. Stage 4
mineralization is marked by the formation of white, barren quartz veins and high-angle normal faults that were developed during D3 extension-related uplift.
Primary two-phase fluid inclusions in quartz of the stringer zone and barite from the
stratiform mineralization homogenize between 132° and 283°C (average ~ 200°C). Salinities of the primary fluid inclusions range from 1.4 to 9.6 wt% NaCl eq. The sulfur isotope compositions of sulfide minerals from stratiform and stockwork
mineralization in the Barika deposit range from delta-34S -0.8 to +5.6 permille. This relatively narrow range suggests that the sulfur in the sulfide mineralization was derived from the leaching of igneous sulfur from the underlying andesitic rocks,
similar to most Japanese Kuroko VMS deposits. Temperatures of formation for Barika sulfides estimated based on sulfur isotope values for coexisting galena-sphalerite (DELTA = 2-4.8 permille) and galena-pyrite (DELTA = -3.3 to -5.4 permille) pairs
range from 146 to 293°C, and these are consistent with fluid inclusion homogenization temperatures. The primary mineralizing fluids have a calculated delta-18O value of between +4.3 and +6.3 permille, based on the delta-18O compositions of quartz
from the stringer zone and assuming a temperature of 200°C and that isotopic equilibrium was attained. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Cette publication explore un gisement d'or et d'argent appelé gisement de Barika en Iran, qui est unique parce qu'il s'agit d'un type de
gisement qui n'a jamais été trouvé dans cette région. Le gisement est situé dans des roches qui ont subi une quantité importante de chaleur et de pression, ce qui les a transformées en faciès de greenschiste inférieur. L'or et l'argent du gisement se
trouvent dans un type spécifique de formation rocheuse, et le gisement est relativement pauvre en métaux de base tels que le plomb, le zinc et le cuivre.
Les scientifiques ont étudié les minéraux présents dans le gisement et ont découvert des
stades de minéralisation distincts, ce qui suggère que divers processus géologiques ont façonné le gisement au fil du temps. Ils ont également analysé la température et la composition des fluides responsables de la formation des
minéraux.
L'importance de cette recherche réside dans la compréhension de l'histoire géologique de ce gisement et de sa formation, ce qui peut aider à l'exploration et à l'extraction de métaux précieux tels que l'or et l'argent dans des contextes
géologiques similaires. Elle contribue à notre connaissance des gisements minéraux et de leur formation, ce qui a des implications pour l'exploitation minière et l'exploration des ressources dans des régions comme l'Iran. |
| GEOSCAN ID | 321874 |
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