东南极埃默里冰架东缘赖茵博尔特丘陵构造变形过程及其构造意义

MULTIPLE DEFORMATIONS IN THE REINBOLT HILLS OF THE EASTERN AMERY ICE SHELF,EAST ANTARCTICA, AND THEIR TECTONIC IMPLICATIONS

对赖茵博尔特丘陵地区的构造变形过程分析表明,该地区发育4期主要构造变形。D1期主要是区域性近EW向片麻理形成阶段,其变形时代为>970 Ma;D2期是在正片麻岩形成了近EW向轴面陡立韧性剪切褶皱,以及剪切面理上发育的各种紧闭不对称褶皱和低角度拉伸线理,其变形时代为新元古代早期。D3期变形发生在寒武纪早期,以构造抬升至地表过程中产生的近EW向高角度正断层为代表,同时在詹宁斯岬地区伴随着紫苏花岗岩侵入;D4期变形为赖茵博尔特丘陵和詹宁斯岬地区NE-NNE向密集破劈理形成阶段,其形成时代可能为晚中生代-新生代。赖茵博尔特丘陵地区D1-2期构造变形与北查尔斯王子山地区构造变形过程类似,应该属于雷纳杂岩的东延部分。在其以北存在早寒武纪(泛非期)的詹宁斯岬紫苏花岗岩体,结合前人资料,推测在两地区之间存在近S-N向的普里兹造山带西部构造边界。据此认为普里兹造山带很可能不通过兰伯特地体,而是向南延伸经过格罗夫山并且通过甘布尔采夫冰下山脉。

From structural analysis and available geochronological data,four principal episodes of deformation（D1—D4） are distinguished in the Reinbolt Hills of the eastern Amery Ice Shelf,East Antarctica.The D1 deformation took place more than 970 Ma ago and is responsible for the formative stage of the EW-trending regional gneissosity in metamorphic rocks.The D2 deformation is characterized by the EW-trending folds with a steep axial plane in orthogneisses that formed in the early Neoproterozoic.Tight asymmetrical folds and low-angle stretching lineations developed on the shear foliations of the rock during this period.The D3 deformation is marked by high-angle normal faults resulting from the early Cambrian tectonic uplift.The emplacement of charnockites in the Jennings Promontory may also be related to this deformational event.The D4 deformation is responsible for the NE-NNE-trending fracture cleavages in the Reinbolt Hills and the Jennings Promontory probably formed during the late Mesozoic to Cenozoic.The D1 and D2 deformational episodes in the Reinbolt Hills may be comparable to those in the northern Prince Charles Mountains,suggesting that the Rayner Complex might extend eastward to the Reinbolt Hills.Taking into account the occurrence of early Cambrian（i.e.,Pan-African） charnockites in the Jennings Promontory,we infer a nearly SN-trending tectonic boundary separating the Reinbolt Hills and Jennings Promontory.Therefore,the Prydz belt might not extend westward to the Lambert terrane,but southward to the Grove Mountains and Gamburtsev Sub-glacial Mountains.