Tectonothermal Evolution of the Cadomian Orogen in the North Armorican Massif and Circum-Atlantic Correlations

北阿莫里安地块是早古生代从北美、波罗的海和冈瓦那分离出来的阿莫里安板块的一部分。Armorica的大部分地区受到晚前寒武纪Cadomian造山作用的影响，该地块是晚古生代华力西造山期间少数几个没有明显Cadomian古老岩石叠印的地区之一。因此，该地区对于解决与相关的阿瓦隆和/或泛非层序的构造联系至关重要。现有的卡多姆造山作用模型有一个有限的地球化学数据库，尽管最近的野外工作表明，发生了复杂的多期前寒武纪变质/构造事件。这项研究将与在该地区工作的英国野外地质学家合作，系统地测定该地块内具有代表性的岩性单位的40Ar/39Ar矿物年龄和选定的锆石U-Pb年龄。已经安排了与法国当地地质学家的合作。这项研究的结果将有助于对前寒武纪构造热事件进行详细评估，并将有助于约束该地区的构造模型。

The North Armorican Massif is part of the Armorican Plate that separated from N. America, Baltica and Gondwana in the early Paleozoic. Large segments of Armorica were affected by the late Precambrian Cadomian orogeny, and the massif is one of very few areas where there is no apparent overprinting of Cadomian aged rocks during the late Paleozoic Variscan orogeny. This area is thus critical for resolution of tectonic linkages with correlative Avalonian and/or Pan-African sequences. Existing models for the Cadomian orogeny have a limited geochemical data base, although recent field work has shown that complex polyphase Precambrian metamorphic/structural events occurred. This study will make systematic determination of 40Ar/39Ar mineral ages and selected U-Pb zircon ages from representative lithological units within the massif, and will be conducted in collaboration with British field geologists working in the area. Co-operation with local French geologists has been arranged. The results of this research will permit detailed evaluation of Precambrian tectonothermal events and will help constrain tectonic models for the region.