Metallogenesis and Tectonics of the Russian Far East, Alaska, and ...

leucogranite plutons form large, homogeneous. batholith-like intrusions with surface areas as large as 7.000 lad. The grmitoid
rocks occur in an axial portion of the Yantt-KoIym collision zone and consist of bide and two-mica granites witb accasory
sill~man~te, andalusite, cordierile a d garnet. High Rb contents art characteristit, the granites are typical S-type colkisional granites
which have init~al Sr ratios rangi~g up 0.7045 to0.71 I1 (Goryachev and Goncha.rov. 1995; Goryachev, 1998,2003). Small Sn
occurrences are associated with these granites.
The Late Jurassic and Early Cretaceous diorite-granodiorik intrusions form nmcrous dikts and small stocks which are
occur as separate suites in central porhons of these zones. Diorite-porphyries grdoriteporphyries, and gmde-pcupbyries rre
most prevalent as dikes; stocks are compc~~d of two and bet rock Kypes. h diorik k~ bidik+mphibde granodiorite or
gran~te. These igneous rocks ere cak-alkaline, with some predominance of No over K, upd M y -&in accessory garnet (ap to
20.5% pyrope), and initial Sr ratios af 0.7045 to 0.7087 (Gcnyachev d Goncharov, 1995; Gory~v, 1988,2003). These
granites are typical I-type granites ofthe ilmenite-series. Au-quark vein deposits are usually associated with theme intrusions.
The Early Cretaceous granodiorite-granite intrusions occur in mull plutons (witb dace -8s of up to 300 km3 m the
same area occupied by the diorite-grenodiorite intrusions. The granodiorite-granite. phtons are composed of granodiolik and
mostly biotite granite rocks, arc characterized by relatively high CaO, low alkali content, with some predominance oSK ovuNa,
and with initial Sr rations of 0.7057 to 0.7087. Accessory minerals are ih~nite, garnet, zircon and sulfide minaals (Gamyanin
and others, 1991). Associated witb these plutons are Au lode and W vein deposits.
Also part of Ihe Yana-Kolyma metahgenic k h are suite of Sn quartz vein and greisen. W vein, 5%-Au and &ticsediment-hosted
Hg occurrences (fig. 61). Notable examples are Sn quartz vein md geisen degmits at Alaskitovoye uxl Burgavli,
the Krokhalin Sb-Au vein occurrence, and the claskic~~l-hosted Hg at Kumih. MU of the Sn deposfts are small, except
for Alaskitovoye.
Figure 69. Natalka Au quartz vein depoait, Yana-Kolyma metallogenic belt, Russian Nowst. Schematic geok@c mp end cross
section. Adapted from Eremin (1995).
Natalka Au Quartz Vein Deposit
The Natalka Au quarb vein deposit (fig. 68) (Fhov, 1957% Shilo, 1960; Voto&h 6~1d
dcts, 1989; Goncharov, 1995;
Erernin and others, 1994) consists of zones of subpuallel and relicdate quartz veinlets wkiich can be g~,uped
into two Or that