HR: 0800h
AN: GP41A-0820    [Abstracts]
TI: Metallogenesis of Gold and Silver in Northeast Russia
AU: * Gamyanin, G N
EM: gamyanin@neisri.magadan.ru
AF: Diamond and Precious Metal Geology Institute, 39 Lenin Avenue, Yakutsk, 677891 Russian Federation
AU: Goryachev, N A
EM: goryachev@neisri.magadan.ru
AF: North-East Interdisciplinary Research Institute, 16 Portavaya St., Magadan, 685000 Russian Federation
AB: Three genetic series of ore lode deposit types in Notheast Russia are distinguished: hydrothermal-metamorphogenic (early collision stage), hydrothermal plutonogenic granitoid (late collisional stage), and volcanogenic (post-collisional stage). Metallogenesis in the hydrothermal-metamorphogenic series is more or less exclusively gold mineralization (gold-quartz veins, and disseminated gold-sulfide mineralization). In the Yana-Kolyma metallogenic belt, gold mineralization of this genetic type occurs as lenticular quartz bodies. In the Allakh-Yun and West Verkhoyansk belts it is present as zones of stratified quartz veins. The hydrothermal-plutonogenic lode deposits related to granitoid suites were produced by ore-magmatic systems (OMS) with similar geochemical specialization for gold that most probably had a palingenetic crustal origin (Rb-Sr and Pb isotopic data). As the collision proceeded, large granitoid plutons were emplaced to form extensive belts (150-140 and 130-120 Ma), within which local ore-magmatic fields were formed. The intermediate-depth magmatic chambers (15-18 km depth) of the OMSs generated the low-sulfide gold-quartz lode deposits, while in hypabyssal magmatic chambers (1-2 km depth) granitoid-related gold lode deposits are produced. The volcanogenic series of shallow-depth ore lode types are silver-base metal, gold-silver-antimony, and silver-mercury. Subduction processes occurring along the Okhotsk active continental margin could have reactivated the earlier strike-slip fault zones, which served as the ore-controlling structures for the development of Late Cretaceous (95-70 Ma) subvolcanic magmatism and the formation of diversified mineralization (silver-base metal, gold-silver-antimony, and silver-mercury). The earliest is silver-base metal mineralization associated with subvolcanic granite porphyries and located in tin ore fields, thus confirming our supposition about the activation of deep horizons of staniferous OMSs. Gold-silver-antimony and silver-mercury mineralizations in narrow metallogenic belts are separate from silver-base metal ore. When the earlier metallogenic belts are cut by later ones, polychronic and polygenetic ore lode deposits are formed. An example is Adycha-Taryn fault zone where gold occurs together with antimony (Sarylakh and Sentachan lode deposits), and gold-mercury (Kyuchus) and tin mineralization are found in combination with silver-antimony mineralization (Kupol'noye and Alyaskitovoye). The combination of various OMSs in Verkhoyansk fold belt led to the formation of large polychronical and polygenetical tin-silver-base metal (Prognoz), or gold-silver (Nezhdaninskoye) lode deposits. The research was conducted with the support of RFBR projects (01-05-65485, 03-05-64980, 03-05-96010, Integration project 65, 69, 71 SB-FEB RAS.
DE: 9315 Arctic region
DE: 9320 Asia
DE: 8155 Plate motions--general
DE: 1525 Paleomagnetism applied to tectonics (regional, global)
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2004 AGU Fall Meeting