origin of the main granitoid belt of northeastern russia: new u-pb geochronology and geochemistry
DESCRIPTION
Origin of the Main Granitoid Belt of Northeastern Russia: New U-Pb Geochronology and Geochemistry. J. Toro, West Virginia University, USA A.V. Prokopiev, RAS, Yakutsk, Russia E.L. Miller, Stanford University, USA V.A. Trunilina, RAS, Yakutsk, Russia A.G. Bakharev, RAS, Yakutsk, Russia. - PowerPoint PPT PresentationTRANSCRIPT
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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
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Cretaceous(?) Granites of NE Russia
Yakutsk
Magadan
Arctic Ocean
Okhotsk Sea
Northern Belt
Main Belt
Tas-KystabytBelt
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Verkhoyansk Thrust beltNorth Asia Craton(Siberia)
Kolyma-Omolonsuperterrane
Okhotsk- Chukotsk
Volcanic
Belt
PacificOcean
Terrain Map after Nokleberg et al. 2001
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Aeromagnetics and Granites
Verkhoyansk
South Anyui Suture
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Scotese, Nokleberg et al. 2001
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Scotese, Nokleberg et al. 2001
130-123 Ma
143-138 Ma
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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
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Cross section across Verkhoyansk - Kolyma orogen
(after Prokopiev, 1998)
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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)
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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
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Chersky Range Granites
Yakutsk
Magadan
Arctic Ocean
Okhotsk Sea
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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
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Main Belt- Chibagalakh 238U/206Pb Ages
200 microns
147±1.6155±1.8
151±1.4154±1.7
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238
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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
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Tas-Kystabyt Belt-Trud Granite
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155-138 Ma
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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
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Geological map of the Verkhoyansk-Kolyma orogen