Time resolution of metamorphic-magmatic events in the Palaeozoic active margin of the northern Wilson Terrane (Ross Orogen, North Victoria Land)

南极洲北维多利亚地的威尔逊地体属于早古生代罗斯增生造山带。花岗岩港侵入岩的高变质和岩浆作用是由地体的岩浆弧背景造成的。从Oates海岸到北部，U-Pb锆石/独居石以及KAr和Ar-Ar云母/角闪石年龄数据尚未获得。这表明在麻粒岩相条件下，在等温减压后发生了~490 ~ 470 Ma的快速冷却，显然不是岩浆弧演化的典型特征。通过对威尔森山、拉扎雷夫山脉和丹尼尔斯山脉的大量样品进行电子探针（EMP）单氮石测年法的广泛筛选，可以更好地了解这些观察结果。成本高、时间短的EMP单独居石定年和相关变质研究可能提供以下信息：(a)罗斯造山热事件；(b)单独居石和石榴石组合的矿物化学数据对比得出的p -t -时间演化；(c)花岗岩港侵入岩组酸性成员的原岩年龄；(d)主要逆冲事件的年龄。该研究为解决早古生代增生造山带岩浆弧地体的地球动力学过程提供了范例。

The Wilson Terrane in North Victoria Land (Antarctica) belongs to the Early-Palaeozoic Ross Accretionary Orogen. High-grade metamorphism and magmatism of the Granite Harbour Intrusives are attributed to a magmatic arc setting of the terrane. U-Pb zircon/monazite as well as KAr and Ar-Ar mica/hornblende age data is yet available from the Oates Coast to the north. It signalize a ~490 - 470 Ma rapid cooling subsequent to isothermal decompression during granulitefacies conditions, apparently untypical for a magmatic arc evolution. A better understanding of these observations can be expected by an extensive screening of metamorphic and magmatic ages in the Wilson Hills, the Lazarev Mountains and the Daniels Range by the electron-microprobe (EMP) monazite dating method on numerous samples recovered during the GANOVEX expedions. The cost and time-efficient EMP monazite dating and related metamorphic studies potentially can provide information on (a) pre-Ross orogenic thermal events, (b) P-T-time evolution by correlation of mineral-chemical data from monazite and garnet-bearing assemblages, (c) protolith ages on acidic members of the Granite Harbour Intrusives suite and (d) ages of the major thrusting events. The study contributes in an exemplaric way to resolve the geodynamic processes in a magmatic arc terrane which is a characteristic part of an Early-Palaeozoic accretionary orogen.