TECTONIC EVOLUTION OF THE ANUY METAMORPHIC ROCKS (SIKHOTE-ALIN, RUSSIA) AND THEIR PLACE IN THE MESOZOIC GEODYNAMIC FRAMEWORK OF EAST ASIA

In Sikhote Alin, the Anuy river provides a representative cross-sectio n of the pre-Eocene structure of the area east of the central Sikhote Alin fault, The Mesozoic rocks are divided into the following groups, from bottom to top: Anuy metamorphic rocks; the Tithonian-Berriasian ( Samarkinsk) accretionary complex; Early Cretaceous (Zhurav-levsk-Tumni n) turbidite; and mid-Cretaceous Al-rich (Khungariisk) granitoids. The Anuy metamorphic rocks have a postfolial NE-SW-trending antiformal st ructure, From bottom to top, they consist of: (1) low-grade schist and sandstone; (2) gneiss and micaschist; (3) migmatite; and (4) ophiolit ic nappe. East-west-trending stretching lineation, isoclinal folds and top-to-the-east shear criteria are found in the ophiolite and migmati te units. These structures are related to ophiolitic thrusting that li kely occurred in Early Cretaceous times. Ar-40/Ar-39 dating of migmati te and metagabbro indicates mid-Cretaceous ages (about 110 Ma) close t o those of the Khungariisk granites. The main deformation, coeval to a high-temperature metamorphism, is characterized by NE-SW-trending str etching lineation with divergent senses of shear, Ar-40/Ar-39 dating o f biotite and muscovite from several lithologies give Late Cretaceous to Paleogene ages (73-58 Ma), This tectono-thermal event is related to NE-SW-trending strike-slip faulting along the central Sikhote Alin fa ult system. The unroofing of the Anuy metamorphic rocks is likely rela ted to granite emplacement. The collision of the Anuy microcontinent w ith Asia can be compared to that of the southern Japan microcontinent.