Origin of the Main Granitoid Belt of Northeastern Russia: New U-Pb Geochronology and GeochemistryJ. Toro, West Virginia University, USAA.V. Prokopiev, RAS, Yakutsk, RussiaE.L. Miller, Stanford University, USAV.A. Trunilina, RAS, Yakutsk, RussiaA.G. Bakharev, RAS, Yakutsk, Russia
Cretaceous(?) Granites of NE Russia
Yakutsk
Magadan
Arctic Ocean
Okhotsk Sea
Northern Belt
Main Belt
Tas-KystabytBelt
Verkhoyansk Thrust beltNorth Asia Craton(Siberia)
Kolyma-Omolonsuperterrane
Okhotsk- Chukotsk
Volcanic
Belt
PacificOcean
Terrain Map after Nokleberg et al. 2001
Aeromagnetics and Granites
Verkhoyansk
South Anyui Suture
Scotese, Nokleberg et al. 2001
Scotese, Nokleberg et al. 2001
130-123 Ma
143-138 Ma
Tectonic Evolution
Parfenov, 1991
Siberia Kolyma Omolon Microcontinent
Oimyakon OceanLate Jurassic (Oxf.-Kimm.)
Late Jurassic (Tithonian)
Early Cretaceous
161-151 Ma
151-145 Ma
145-100 Ma
Cross section across Verkhoyansk - Kolyma orogen
(after Prokopiev, 1998)
Trace Element CharacteristicsYakutian and Andean Granitoids
1.00
10.00
100.00
1000.00
1.00 10.00 100.00 1000.00
Y+Nb (ppm)
Rb
(ppm
)
Main Belt Northern Belt Tas-Kystabyt Andean Granitoids
CollisionWithin Plate
OrogenicVolcanic Arc
Granitoid tectonic discrimination diagram (Pearce et al. 1984)
U-Pb Zircon Geochronology• 10 Main Belt Plutons• 4 Northern Belt Plutons• 5 Tas Kystabyt Granites and Sub-volcanics• 2 Uyandina-Yasachnida Volcanics
• USGS/STANFORD SHRIMP-RG• At least 10 zircons per sample• Rims and cores
Chersky Range Granites
Yakutsk
Magadan
Arctic Ocean
Okhotsk Sea
Main Belt Granites-Chersky Range
100 km
Chibagalakh
Porozhnotsepinsky
Pravo-Tuostakh
Nelkan
ChugulukUst Nera
Khayargastakh
Chimalga
Pravo Kharaulakh
Ar/Ar=131-143
Ar/Ar=143
Ar/Ar=144
Main Belt- Chibagalakh 238U/206Pb Ages
200 microns
147±1.6155±1.8
151±1.4154±1.7
238
Main Belt Granites-Chersky Range
100 km
Chibagalakh
Porozhnotsepinsky
Pravo-Tuostakh
Nelkan
ChugulukUst Nera
Khayargastakh
Chimalga
Pravo Kharaulakh
145-155 Ma
148-154 Ma
151 Ma
147-156 Ma
154±1.2 Ma
155±1.4 Ma
148±1 Ma, 2 Ga cores
84±1 Ma
Tas-Kystabyt Belt-Trud Granite
155-138 Ma
Conclusions
• Magmatism in the Main Belt 155-145 Ma• Main Belt Granitoids are coeval with
Uyandina-Yasachnida Arc• Main Belt is probably subduction related, not
collisional• Subduction under Verkhoyansk Margin during
Late Jurassic(?)→ Tas-Kystabyt• Northern Belt is 126-136 Ma
Geological map of the Verkhoyansk-Kolyma orogen
