Paleozoic orogens in New England, USA
Paleozoic orogens in New England, USA
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美国新英格兰古生代造山带
作者：
P. Robinson;R. Tucker;D. Bradley;Henry N Berry Iv;P. Osberg
摘要阿巴拉契亚山脉结晶核的地层学和同位素地质年代学对新英格兰古生代造山带的范围、性质和时间提出了新的解释。岩浆作用、变形作用和高级区域变质作用共经历了五个主要阶段：塔昆期（455-442 Ma）、克拉里昂期（423-385 Ma）、新克拉里昂期（366-350 Ma）、晚宾夕法尼亚期（300-290 Ma）和阿勒格尼期（280-260 Ma）。在塔康期，劳伦大陆的被动边缘被俯冲到一个复杂的岩浆弧之下，该岩浆弧持续了480 - 442 Ma，部分形成于一个可能与亚马逊河流域有密切关系的中新英格兰陆壳之上。关于中部新英格兰的问题包括它作为一个单一板块的连贯性，以及它下面地壳的性质。西印度群岛始于晚志留世，是融合的劳伦蒂亚-中新英格兰和复合阿瓦隆沿着沿海缅因州的一条隐蔽缝合线的外带之间的碰撞，并在2000年中期向西北推进到康涅狄格河谷盆地。
Abstract Stratigraphy and isotope geochronology in the crystalline core of the Appalachians suggest revised interpretations of the extent, nature and timing of Paleozoic orogens in New England. Five major episodes of magmatism, deformation, and high-grade regional metamorphism are recognized: Taconian (455-442 Ma), Acadian (423-385 Ma), Neo-Acadian (366-350 Ma), Late Pennsylvanian (300-290 Ma) and Alleghanian (280-260 Ma). In the Taconian, the passive margin of Laurentia was subducted below a complex magmatic arc lasting from 480 to 442 Ma, founded in part on continental crust of a Medial New England terrane with possible affinities with Amazonia. Questions about Medial New England involve its coherence as a single plate, and the nature of its underlying crust. The Acadian began in Late Silurian as a collision between the amalgamated Laurentia-Medial New England and outer belts of Composite Avalon along a cryptic suture in coastal Maine, and progressed northwestward to the Connecticut Valley basin by mid-...