ABSTRACT

The Ross orogenic belt in Antarctica is one of several Neoproterozoic-early Palaeozoic orogens that crisscrossed Gondwana and are associated with Gondwana’s assembly. We present new age data from the Queen Maud Mountains, Ross orogen, from areas that hitherto have lacked precise ages from the local plutonic rocks. The zircon U-Pb igneous crystallization ages (n = 7) and a hornblende ⁴⁰Ar/³⁹Ar cooling age (n = 1) constrain plutonism to primarily lie within the Cambrian to Ordovician. Cumulative zircon U-Pb crystallization age data yield polymodal age distributions (516 Ma, 506–502 Ma, and 488 Ma age peaks) that are similar to other areas of the Queen Maud-Horlick Mountains, consistent with regional magmatic flare-ups along the Pacific-Gondwana margin during these times. The ages of deformed plutons constrain deformation to the Cambrian (Series 2) to Ordovician (Lower), with some regions indicating a transition to post-tectonic magmatism and cooling at ~509-470 Ma. Collectively, the data indicate that the Queen Maud-Horlick Mountains share a similar petrotectonic history with other regions of the Pacific-Gondwana margin, providing new evidence that this tectonostratigraphic province is part of and not exotic to the larger igneous-sedimentary successions developed in the peri-Gondwana realm under a broadly convergent margin setting.

摘要

南极洲的罗斯造山带是几个新元古代-早古生代造山带之一，它们在冈瓦纳大陆上纵横交错，并与冈瓦纳大陆的集合有关。我们提供了来自罗斯造山带的莫德皇后山脉的新时代数据，这些地区迄今为止缺乏来自当地深成岩的精确年龄。锆石 U-Pb 火成岩结晶年龄 (n = 7) 和角闪石⁴⁰ Ar/ ³⁹Ar 冷却年龄 (n = 1) 限制深成作用主要位于寒武纪至奥陶纪。累积的锆石 U-Pb 结晶年龄数据产生多峰年龄分布（516 Ma、506-502 Ma 和 488 Ma 年龄峰值），与皇后莫德-霍里克山脉的其他地区相似，与沿该地区的区域岩浆爆发一致这些时期的太平洋-冈瓦纳边缘。变形岩体的年龄将变形限制在寒武纪（系列 2）到奥陶纪（下），一些地区表明在~509-470 Ma 过渡到后构造岩浆作用和冷却。总的来说，数据表明莫德女王-霍里克山脉与太平洋-冈瓦纳边缘的其他地区有着相似的岩石构造历史，