东南极格罗夫山冰碛岩特征及对冰下地质的限定

东南极格罗夫山被认为是普里兹造山带向南极内陆的延伸部分,其构造属性为普里兹造山带构造性质提供重要制约。格罗夫山大面积被冰雪所覆盖,零星的基岩露头无法全面反映格罗夫山的地质特征。分布于格罗夫山冰原岛峰附近的冰碛岩可能携带着冰盖之下(冰下高地)更大、更深范围的地质信息,对揭示整个格罗夫山的物质组成和构造演化具有不可替代的作用。在对格罗夫山碎石带中冰碛岩种类和分布特征进行总结的基础上,评述了近10年来格罗夫山冰碛岩的岩石学、同位素年代学和锆石Hf同位素等方面的研究结果,得出格罗夫山冰下高地比基岩具有更加复杂的岩石组成,且只经历了泛非期单相变质旋回。高压麻粒岩在格罗夫山冰碛岩中的广泛分布表明格罗夫山冰下高地或者高地的一部分普遍经历了泛非期高压麻粒岩相变质作用。与查尔斯王子山—普里兹湾地区其他地体进行对比,格罗夫山冰下高地略早的变质作用时间和较高的变质作用程度表明普里兹造山带的缝合线位置可能位于格罗夫山冰下高地以南。

Characteristics of Glacial Moraines in Grove Mountains,East Antarctica: Constraints on the Subglacial Geology

The Grove Mountains are considered as inland continuation of Prydz belt in East Antarctica, and could provide important constraints for the tectonic nature of Prydz belt. Most of the basement in Grove Mountains is hidden beneath the ice sheet, the sparse exposures of bedrocks are insufficient to fully show the geological characteristics of the entire Grove Mountains. A number of moraine belts exposed on the glaciers of Grove Mountains may carry information about the geology of Grove subglacial highlands in greater scope and depth, and play an irreplaceable role in revealing the material composition and tectonic evolution of Grove Mountains. The types and distribution characteristics of glacial moraines in Grove Mountains were summarized, and the study on petrology, isotopic chronology and zircon Hf isotopic analysis of the glacial moraines in Grove Mountains in the recent decades was reviewed. The subglacial highlands are more complex in composition to the exposed bedrock in Grove Mountains, which only experience a single Pan-African metamorphic cycle. The wide distribution of high-pressure granulites suggests that at least part of Grove subglacial highlands undergo Pan-African high-pressure granulite facies metamorphism. In contrast with Prince Charles Mountains-Prydz Bay region, the Grove subglacial highlands have earlier metamorphic ages and higher degree of metamorphism, suggesting that the collision suture of Prydz belt should lie to the south of Grove subglacial highlands.