HR: 0800h
AN: GP41A-0823    [Abstracts]
TI: Geodynamic setting, geochemistry, U-Pb datings and mafic enclave composition of granitoids from Eastern- and Prybrezhny Taigonos belts (southern part of Taigonos Peninsula, NE Russia)
AU: * Luchitskaya, M V
EM: luchitskaya@ginras.ru
AF: Geological Institute Billing Address: AGU City: Washington Zip/Postal: 20009 Country Code: USA Name: Enter your name Phone: Enter your Telephone Number , Pyzhevsky 7, Moscow, 119017 AU: Hourigan, J
AF: Yale University, New Haven, CT 06520-2109, New Haven, 208109 United States
AU: Silantyev, S A
EM: silantyev@geokhi.ru
AF: Institute of Geochemistry and Analytical Chemistry, Kosygina St. 19, Moscow, 119991 Russian Federation
AB: The Taigonos Peninsula is divided into the following terranes: Avekov, Central Taigonos, and Beregovoi. The Avekov terrane consists of the Precambrian and Pz1 metamorphic complexes and the Central Taigonos terrane - Pz2-K1 island-arc complexes. The Central and Beregovoi terranes are separated by the Eastern Taigonos granitoid belt (ETb). The Beregovoi terrane represents a fragment of accretionary prism, which consists of T-K1 volcanogenic, siliceous and terrigenous sheets separated by serpentinite melange. Small plutons of the Pribrezhnyi Taigonos belt (PTb) intrude accretionary prism of the Beregovoi terrane. The 40Ar/39Ar datings from granites of the: (1) ETb are 103.3­A0.3 and 103.1­A0.5 Ma; (2) PTb are 100.9­A0.6, 101.3­A0.5, 103.5­A1.9 Ma. U-Pb datings on zircons indicate that granitoids of the ETb were emplaced and crystallized between 104.6­A1.1 and 97.0­A1.1 Ma, those of the PTb, between 106.5­A0.9 and 105.5­A0.9 Ma. ETb is mainly composed of tonalites and granodiorites. PTb is composed of small gabbro-diorite-tonalite plutons. Granitoids of ETb and PTb are metaluminous rocks, (Nb/Zr)n vs Zr and Rb vs Y+Nb show that they are subduction related rocks, they are characterized by LILE enrichment and HFSE depletion in relation to ORG, with distinct Ta and Nb depletion. Granites of ETb are more enriched in LREE, with more fractionated REE patterns. They also belong to high-K calc-alkaline and calc-alkaline series in terms of K2O and SiO2 concentrations, whereas granitoids of PTb, only to calc-alkaline series. Granitoids of both belts contain mafic enclaves (MME). Based on mineralogy and geochemistry MME from granitoids of PTb (gabbros, gabbro-diorites) are ascribed as plutonic derivatives of subalkaline magmatism that produces calc-alkaline island-arc series. P"CT estimates for rocks of gabbro-diorite-tonalite massif in the of PTb and enclaves in them show several stages of their evolution: 1) magmatic T= 800"C1000… 3 and P= 5"C10 šb; 2) recrystallization of enclaves, T=610-800… 3, P= 5"C10 šb; 3) metamorphism '=500"C590… 3, ý=3"C4 šb and ' ­š 450"C500… 3, ý ­š 2 kb. Diversity of petrographycal types of ET pluton, large volume of granitoid magmatism in ETb, prevailing of granodiorite, tonalites and geochemistry of rocks allow to refer these granitoids to Cordilleran I-type granites; granitoids of PTb are similar to M-type subduction related granites. Supported by RFBR, grant 04-05-65132
DE: 8109 Continental tectonics--extensional (0905)
DE: 3655 Major element composition
DE: 3670 Minor and trace element composition
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2004 AGU Fall Meeting