黑龙江嫩江地区科洛杂岩伸展构造特征

摘要

黑龙江省嫩江县科洛杂岩位于大兴安岭北段.详细的构造解析揭示,科洛杂岩内发育一处大型滑脱构造,其中包括鞘褶皱、层间柔皱、不对称褶皱、S-C组构、眼球状构造等构造样式,整体反映杂岩体向sE伸展滑脱的特征.结合年代学和岩石学方面的证据,认为科洛杂岩伸展滑脱始于中侏罗世晚期或稍后,其隆升机制应源于大兴安岭地区中、晚侏罗世岩浆的强烈底侵作用,导致整体隆升造山,伴随区域伸展滑脱,形成变质核杂岩.这为大兴安岭北段隆升机制和构造样式的研究提供了新证据.%Keluo complex at Nenjiang area in Heilongjiang Province is located in the northern part of the Daxing'anling Mountains.By detailed field work and structural analysis we found that the Keluo complex has developed a large scale detachment structure, including sheath folds, wrinkle in soft layer, asymmetric folds, S-C fabric, elongated lenses, eye-like structure, drag structure and so on,which suggests a top to south-east extensional sliding. Combining with the chronologic and petrological evidences, we think that the extensional deformation of Keluo complex should happen in Late Jurassic in Daxing'anling region, and resulted in the uplift of Daxing'anling Mountains and the regional extensional detachment, and formed the metamorphic core complex. Our research on extensional structure of Keluo complex provides a new evidence for the uplift mechanism study of Daxing'anling Mountains.