LA-ICP-MS U-PB DATING AND HF ISOTOPIC COMPOSITIONS OF DETRITAL ZIRCONS FROM THE “PERMIAN” SANDSTONES IN DA HINGGAN MOUNTAINS, NE CHINA: CONSTRAINTS ON THE EVOLUTION OF THE EASTERN SEGMENT OF CENTRAL ASIAN OROGENIC BELT
Synthesizing this unique information on a magmatic arc of an approximate age of 320 Ma we define a distribution of the Sonidzuoqi–Xilinhot magmatic arc as follows. The arc extends from Solon Obo via Sonidzuoqi, Xilinhot through Ulanhot to Qiqihar, and then it is cut by the sinistral Nenjiang-Balihan slip-strike fault (western boundary fault of the Songliao basin), and ultimately extends to Longzhen in the northern sectors of the Da Hinggan Mountains. The Erenhot-Hegenshan suture zone is located north of this magmatic arc. Further Paleozoic age groups of ~380 Ma, ~430 Ma and ~500 Ma in the samples indicate a mixture of age groups of variable origin and multiple arc-continent accretion during the formation of the composite Erguna-Hinggan-Songliao block. The sample from the uppermost Permian to Lower Triassic Linxi Formation in the Linxi area (in the southern segment of Da Hinggan Mountains) has two age groups of ~1800 Ma and ~2500 Ma, indicating their source from the northern margin of the North China craton located in the south. Therefore, the collision between the North China craton and the Hinggan-Erguna block started during the deposition of the Linxi Formation and the final closure of the intervening oceanic basin occurred during Late Permian-Early Triassic forming the Ondor Sum-Xar Moron suture zone.