| Autor: |
Chitalin, Andrey F., Baksheev, Ivan A., Nikolaev, Yurii N., Nagornaya, Ekaterina V., Khabibullina, Yuliya N., Nikolaeva, Irina Yu., Kalko, Ildar A., Müller, Daniel |
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| Zdroj: |
Mineralium Deposita; Feb2023, Vol. 58 Issue 2, p287-306, 20p |
| Abstrakt: |
The Nakhodka ore field (NOF) is situated in the Baimka Trend, Chukotka, Russia, and comprises the Vesenny epithermal Au–Ag, and Malysh, Nakhodka, Vesenny III, and Pryamoy porphyry Cu-Au ± Mo deposits. Porphyry and epithermal mineralization of the NOF are hosted by Early Cretaceous diorite and monzonite intrusions, which are dated at 139–141 Ma (U–Pb zircon). The NOF mineralization is structurally controlled. The prevailing stress field during the evolution in the Baimka dextral shear zone (also known as Baimka Trend) has led to the formation of extensional and strike-slip structures that control distinct zones with strong quartz-sericite alteration and sheeted high-grade quartz–sulfide veining; characteristics that are similar to the world-class Peschanka porphyry Cu-Au deposit located about 20 km to the NW of the NOF. Four types of hydrothermal alteration are documented in the NOF: (1) potassic, (2) propylitic, (3) quartz-sericite, and more rarely (4) argillic. Two phases of porphyry-style mineralization are distinguished: (1) early-stage quartz-magnetite veining associated with potassic alteration and (2) sheeted quartz-sulfide (bornite, chalcopyrite, molybdenite, pyrite) veining that is spatially associated with a strong quartz-sericite alteration assemblage. Epithermal Au–Ag mineralization belongs to the intermediate-sulfidation type and consists of gold-bearing polymetallic quartz-dolomite ± rhodochrosite veins and veinlets. The NOF is defined by a distinct geochemical zonation. Geophysical data show that the high-grade stockwork zones at the Vesenny III porphyry Cu-Au deposit are defined by pronounced magnetic anomalies reflecting abundant hydrothermal magnetite veining, while the Vesenny epithermal Au–Ag deposit is defined by a strong negative magnetic anomaly due to strong silicification and magnetite-destructive quartz-sericite to argillic alteration. [ABSTRACT FROM AUTHOR] |
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Complementary Index |
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